ISO 11277:2009
(Main)Soil quality - Determination of particle size distribution in mineral soil material - Method by sieving and sedimentation
Soil quality - Determination of particle size distribution in mineral soil material - Method by sieving and sedimentation
ISO 11277:2009 specifies a basic method of determining the particle size distribution applicable to a wide range of mineral soil materials, including the mineral fraction of organic soils. It also offers procedures to deal with less common soils. ISO 11277:2009 has been developed largely for use in the field of environmental science, and its use in geotechnical investigations is something for which professional advice might be required. A major objective of ISO 11277:2009 is the determination of enough size fractions to enable the construction of a reliable particle-size-distribution curve. ISO 11277:2009 does not apply to the determination of the particle size distribution of the organic components of soil, i.e. the more or less fragile, partially decomposed, remains of plants and animals. It is also realized that the chemical pretreatments and mechanical handling stages in ISO 11277:2009 could cause disintegration of weakly cohesive particles that, from field inspection, might be regarded as primary particles, even though such primary particles could be better described as aggregates. If such disintegration is undesirable, then ISO 11277:2009 is not used for the determination of the particle size distribution of such weakly cohesive materials.
Qualité du sol — Détermination de la répartition granulométrique de la matière minérale des sols — Méthode par tamisage et sédimentation
L'ISO 11277:2009 spécifie une méthode de base de détermination de la répartition granulométrique des matières minérales des sols, y compris la fraction minérale des sols organiques. Elle propose également des modes opératoires permettant de traiter des sols particuliers. L'ISO 11277:2009 a été élaborée pour être largement utilisée dans le domaine de la science de l'environnement, et son utilisation dans des recherches géotechniques est un point pour lequel un avis professionnel peut se révéler nécessaire. Un objectif majeur de l'ISO 11277:2009 est la détermination d'un nombre suffisant de fractions granulométriques pour permettre la construction d'une courbe de répartition granulométrique fiable. L'ISO 11277:2009 ne s'applique pas à la détermination de la répartition granulométrique des composants organiques du sol, à savoir les restes plus ou moins fragiles, partiellement décomposés, de plantes ou d'animaux. Il est également à noter que les traitements chimiques préalables et les étapes de manipulation mécanique dans l'ISO 11277:2009 peuvent entraîner la désintégration de particules à faible cohérence qui, du point de vue d'une inspection sur le terrain, pourraient être considérées comme des particules primaires et mieux décrites en tant qu'agrégats. Si cette désintégration n'est pas souhaitable, alors l'ISO 11277:2009 n'est pas utilisée pour la détermination de la répartition granulométrique de ces matières à faible cohérence.
Kakovost tal - Določevanje porazdelitve velikosti delcev v mineralnem delu tal - Metoda s sejanjem in usedanjem
Ta mednarodni standard opredeljuje osnovno metodo za določevanje porazdelitve velikosti delcev, ki se uporablja za širok razpon mineralnega dela tal, vključno z mineralno frakcijo organskih tal. Prav tako ponuja postopke za obravnavanje manj običajnih tal, navedenih v uvodu. Ta mednarodni standard je bil razvit v glavnem za uporabo v okoljski znanosti in njegova uporaba pri geotehničnih raziskavah je nekaj, za kar je morda potreben strokovni nasvet.
Glavni cilj tega mednarodnega standarda je določevanje dovolj frakcij velikosti, ki omogočajo izdelavo zanesljive krivulje porazdelitve velikosti delcev.
Ta mednarodni standard ne velja za določevanje porazdelitve velikosti delcev organskih sestavin tal, tj. bolj ali manj krhkih, delno razgrajenih ostankov rastlin in živali. Zavedamo se tudi, da stopnje kemične priprave in mehanskega ravnanja v tem mednarodnem standardu lahko povzročijo razpad šibko povezanih delcev, ki jih pri poljskem pregledu lahko štejemo za primarne delce, čeprav bi take primarne delce bolje opisali kot skupke. Če je tak razpad nezaželen, se ta mednarodni standard ne uporablja za določevanje porazdelitve velikosti delcev takih šibko povezanih materialov.
General Information
Relations
Frequently Asked Questions
ISO 11277:2009 is a standard published by the International Organization for Standardization (ISO). Its full title is "Soil quality - Determination of particle size distribution in mineral soil material - Method by sieving and sedimentation". This standard covers: ISO 11277:2009 specifies a basic method of determining the particle size distribution applicable to a wide range of mineral soil materials, including the mineral fraction of organic soils. It also offers procedures to deal with less common soils. ISO 11277:2009 has been developed largely for use in the field of environmental science, and its use in geotechnical investigations is something for which professional advice might be required. A major objective of ISO 11277:2009 is the determination of enough size fractions to enable the construction of a reliable particle-size-distribution curve. ISO 11277:2009 does not apply to the determination of the particle size distribution of the organic components of soil, i.e. the more or less fragile, partially decomposed, remains of plants and animals. It is also realized that the chemical pretreatments and mechanical handling stages in ISO 11277:2009 could cause disintegration of weakly cohesive particles that, from field inspection, might be regarded as primary particles, even though such primary particles could be better described as aggregates. If such disintegration is undesirable, then ISO 11277:2009 is not used for the determination of the particle size distribution of such weakly cohesive materials.
ISO 11277:2009 specifies a basic method of determining the particle size distribution applicable to a wide range of mineral soil materials, including the mineral fraction of organic soils. It also offers procedures to deal with less common soils. ISO 11277:2009 has been developed largely for use in the field of environmental science, and its use in geotechnical investigations is something for which professional advice might be required. A major objective of ISO 11277:2009 is the determination of enough size fractions to enable the construction of a reliable particle-size-distribution curve. ISO 11277:2009 does not apply to the determination of the particle size distribution of the organic components of soil, i.e. the more or less fragile, partially decomposed, remains of plants and animals. It is also realized that the chemical pretreatments and mechanical handling stages in ISO 11277:2009 could cause disintegration of weakly cohesive particles that, from field inspection, might be regarded as primary particles, even though such primary particles could be better described as aggregates. If such disintegration is undesirable, then ISO 11277:2009 is not used for the determination of the particle size distribution of such weakly cohesive materials.
ISO 11277:2009 is classified under the following ICS (International Classification for Standards) categories: 13.080.20 - Physical properties of soils. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 11277:2009 has the following relationships with other standards: It is inter standard links to ISO 11277:2020, ISO 11277:1998/Cor 1:2002, ISO 11277:1998. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
You can purchase ISO 11277:2009 directly from iTeh Standards. The document is available in PDF format and is delivered instantly after payment. Add the standard to your cart and complete the secure checkout process. iTeh Standards is an authorized distributor of ISO standards.
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 11277
Second edition
2009-09-15
Soil quality — Determination of particle
size distribution in mineral soil
material — Method by sieving and
sedimentation
Qualité du sol — Détermination de la répartition granulométrique de la
matière minérale des sols — Méthode par tamisage et sédimentation
Reference number
©
ISO 2009
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ii © ISO 2009 – All rights reserved
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terminology and symbols.2
4 Principle.2
5 Field sampling .4
6 Sample preparation .4
7 Dry sieving (material > 2 mm).4
8 Wet sieving and sedimentation (material < 2 mm) .7
9 Precision.20
10 Test report.21
Annex A (normative) Determination of particle size distribution of mineral soil material that is not
dried prior to analysis.22
Annex B (normative) Determination of particle size distribution of mineral soils by a hydrometer
method following destruction of organic matter .25
Bibliography.34
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11277 was prepared by Technical Committee ISO/TC 190, Soil quality.
This second edition cancels and replaces the first edition (ISO 11277:1998), of which it constitutes a minor
revision, and incorporates ISO 11277:1998/Cor.1:2002.
iv © ISO 2009 – All rights reserved
Introduction
The physical and chemical behaviour of soils is controlled in part by the amounts of mineral particles of
different sizes in the soil. The subject of this International Standard is the quantitative measurement of such
amounts (expressed as a proportion or percentage of the total mass of the mineral soil), within stated size
classes.
The determination of particle size distribution is affected by organic matter, soluble salts, cementing agents
(especially iron compounds), relatively insoluble substances such as carbonates and sulfates, or combinations
of these. Some soils change their behaviour to such a degree, upon drying, that the particle size distribution of
the dried material bears little or no relation to that of the undried material encountered under natural conditions.
This is particularly true of soils rich in organic matter, those developed from recent volcanic deposits, some
highly weathered tropical soils, and soils often described as “cohesive” (Reference [3] in the Bibliography).
Other soils, such as the so-called “sub-plastic” soils of Australia, show little or no tendency to disperse under
normal laboratory treatments, despite field evidence of a large clay content.
The procedures given in this International Standard recognize these kinds of differences between soils from
different environments, and the methodology presented is designed to deal with them in a structured manner.
Such differences in soil behaviour can be very important, but awareness of them depends usually on local
knowledge. Given that the laboratory is commonly distant from the site of the field operation, the information
supplied by field teams becomes crucial to the choice of an appropriate laboratory procedure. This choice can
be made only if the laboratory is made fully aware of this background information.
INTERNATIONAL STANDARD ISO 11277:2009(E)
Soil quality — Determination of particle size distribution in
mineral soil material — Method by sieving and sedimentation
WARNING — All procedures in this International Standard must be carried out by competent, trained
persons, with adequate supervision. Attention is drawn to certain known hazards, but it is essential
that users follow safe working practices. If in any doubt, seek professional advice.
It is essential that users of this International Standard read all of it before commencing any operation,
as failure to note certain points will lead to incorrect analysis and could be dangerous.
1 Scope
This International Standard specifies a basic method of determining the particle size distribution applicable to
a wide range of mineral soil materials, including the mineral fraction of organic soils. It also offers procedures
to deal with the less common soils mentioned in the introduction. This International Standard has been
developed largely for use in the field of environmental science, and its use in geotechnical investigations is
something for which professional advice might be required.
A major objective of this International Standard is the determination of enough size fractions to enable the
construction of a reliable particle-size-distribution curve.
This International Standard does not apply to the determination of the particle size distribution of the organic
components of soil, i.e. the more or less fragile, partially decomposed, remains of plants and animals. It is also
realized that the chemical pretreatments and mechanical handling stages in this International Standard could
cause disintegration of weakly cohesive particles that, from field inspection, might be regarded as primary
particles, even though such primary particles could be better described as aggregates. If such disintegration is
undesirable, then this International Standard is not used for the determination of the particle size distribution of
such weakly cohesive materials.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 565:1990, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal
sizes of openings
ISO 3310-1:2000, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3310-2:1999, Test sieves — Technical requirements and testing — Part 2: Test sieves of perforated
metal plate
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods
ISO 11464:2006, Soil quality — Pretreatment of samples for physico-chemical analysis
3 Terminology and symbols
3.1 Terminology
Particles within particular size ranges or classes are commonly described as cobbles, gravel, coarse sand, silt,
etc. The meaning of such trivial names differs between countries, and in some cases there are no exact
translations of such words from one language to another; for example, the Dutch word “zavel” has no
equivalent in English. The only fraction for which there appears to be common agreement is clay, which is
defined as material of less than 0,002 mm equivalent spherical diameter (References [1, 3] in the
Bibliography). Such trivial names shall not be used in describing the results of particle size determination
according to this International Standard. Phrases such as “. passing a 20 mm aperture sieve .” or “. less
then 0,063 mm equivalent spherical diameter .” shall be used instead. If trivial names must be used, for
example, to cross-reference to another International or National Standard, then the trivial name should be
defined explicitly, so as to remove any doubt as to the meaning intended, e.g. silt (0,063 mm to 0,002 mm
equivalent spherical diameter) (see Clause 4). Furthermore, it is common to use the word “texture” to describe
the results of particle-size-distribution measurements, e.g. “the particle size of this soil is of clay texture”. This
is incorrect as the two concepts are different, and the word “texture” shall not be used in the test report
(Clause 10) to describe the results obtained by the use of this International Standard.
It is common to refer to sieves as having a particular mesh-size or mesh number. These are not the same as
the sieve aperture, and the relationship between the various numbers is not immediately obvious. The use of
mesh numbers as a measurement of particle size is difficult to justify, and shall not be used in reporting the
results of this International Standard.
3.2 Symbols
The following symbols are found throughout the text and, where appropriate, units and quantities are as given
below (the SI convention is followed for common units, e.g. g = gram; m = metre; mm = millimetre; s = second,
etc.).
Mg megagram (10 g);
mPa millipascal;
t is the settling time, in seconds, of a particle of diameter d ;
p
η is the dynamic viscosity of water at the test temperature (see Table B.2), in millipascals per second;
h is the sampling depth, in centimetres;
ρ is the mean particle density, in megagrams per cubic metre (taken as 2,65 Mg/m ; see the note in
s
Clause 4);
ρ is the density of the liquid containing the soil suspension, in megagrams per cubic metre (taken as
w
1,00 Mg/m ; see the note in Clause 4);
g is the acceleration due to gravity, in centimetres per second squared (taken as 981 cm/s );
d is the equivalent spherical diameter of the particle of interest, in millimetres.
p
4 Principle
The particle size distribution is determined by a combination of sieving and sedimentation, starting from air-
dried soil (Reference [3] in the Bibliography) (see note below). A method for undried soil is given in Annex A.
Particles not passing a 2 mm aperture sieve are determined by dry sieving. Particles passing such a sieve, but
retained on a 0,063 mm aperture sieve, are determined by a combination of wet and dry sieving, whilst
2 © ISO 2009 – All rights reserved
particles passing the latter sieve are determined by sedimentation. The pipette method is preferred. A
hydrometer method is given in Annex B. A combination of sieving and sedimentation enables the construction
of a continuous particle-size-distribution curve.
The key points in this procedure are summarized as a flow chart in Figure 2. This International Standard
requires that the proportions of fractions separated by sedimentation and sieving be determined from the
masses of such fractions obtained by weighing. Other methods of determining the mass of such fractions rely
on such things as the interaction of particles with electromagnetic radiation or electrical fields (Reference [1] in
the Bibliography). There are often considerable difficulties in relating the values obtained by these different
methods for the same sample. It is one of the intentions of this International Standard that close adherence to
its details should help minimize interlaboratory variation in the determination of the particle size distribution of
mineral soils. Therefore, the proportions of fractions shall be determined only by weighing. If this is not the
method used, then compliance with this International Standard cannot be claimed in the test report
(Clause 10).
Both the pipette and hydrometer methods assume that the settling of particles in the sedimentation cylinder is
in accordance with Stokes's Law (References [1, 3, 6] in the Bibliography), and the constraints that this
implies, namely:
a) the particles are rigid, smooth spheres;
b) the particles settle in laminar flow, i.e. the Reynolds Number is less than about 0,2; this constraint sets an
upper equivalent spherical particle diameter (see below) slightly greater than 0,06 mm for Stokesian
settling under gravity (Reference [1] in the Bibliography);
c) the suspension of particles is sufficiently dilute to ensure that no particle interferes with the settling of any
other particle;
d) there is no interaction between the particle and fluid;
e) the diameter of the suspension column is large compared to the diameter of the particle, i.e. the fluid is of
“infinite extent”;
f) the particle has reached its terminal velocity;
g) the particles are of the same relative density.
Thus, the diameter of a particle is defined in terms of the diameter of a sphere whose behaviour in suspension
matches that of the particle. This is the concept of equivalent spherical diameter. It is the principle upon which
the expression of the diameter of particles, as derived from sedimentation, is based in this International
Standard.
Stokes's Law can be written, for the purposes of this International Standard, in the form:
⎡⎤
th=−18ηρ ρgd
()
sw p
⎣⎦
where
t is the settling time, in seconds, of a particle of diameter d (see below);
p
η is the dynamic viscosity of water at the test temperature (see Table B.2), in millipascals per second;
h is the sampling depth, in centimetres;
ρ is the mean particle density, in megagrams per cubic metre (taken as 2,65 Mg/m ; see note);
s
ρ is the density of the liquid containing the soil suspension, in megagrams per cubic metre (taken as
w
1,00 Mg/m ; see note);
g is the acceleration due to gravity, in centimetres per second squared (taken as 981 cm/s );
d is the equivalent spherical diameter of the particle of interest, in millimetres.
p
NOTE It is realized that there are considerable differences between the densities of soil particles, but for the
purposes of this International Standard it is assumed that the mean particle density is that of quartz, i.e. 2,65 Mg/m
(Reference [7] in the Bibliography), as this is the commonest mineral in a very wide range of soils. The density of water is
3 3
0,998 2 Mg/m and 0,995 6 Mg/m at 20 °C and 30 °C, respectively (Reference [5] in the Bibliography). Given the effect of
the addition of a small amount of dispersant (see 8.3.2), the density of water is taken as 1,000 0 Mg/m over the permitted
temperature range of this International Standard (8.2.2).
Furthermore, for routine use, it is recommended that the sampling times be converted to minutes and/or hours,
as appropriate, to lessen the risk of error (see Table 3).
5 Field sampling
The mass of sample taken in the field shall be representative of the particle size distribution, especially if the
amount of the larger particles is to be determined reliably. Table 1 gives recommended minimum masses.
6 Sample preparation
Samples shall be prepared in accordance with the methods given in ISO 11464.
NOTE For many purposes, particle size distribution is determined only for the fraction of the soil passing a 2 mm
aperture sieve. In this case, the test sample (8.5) can be taken either according to the procedures in ISO 11464 or from
the material passing a 2 mm aperture sieve according to 7.2.
7 Dry sieving (material > 2 mm)
7.1 General
The procedure specified in this clause applies to material retained on a 2 mm aperture sieve. Table 2 gives
the maximum mass which shall be retained on sieves of different diameters and apertures. If more than this
amount of material is retained, then it shall be subdivided appropriately and resieved.
7.2 Apparatus
7.2.1 Test sieves, with apertures which comply with ISO 565, and with well-fitting covers and receivers.
The full range of sieves appropriate to the largest particle(s) present should be used (see Table 1 and 7.2.3).
The apertures chosen shall be stated in the test report (Clause 10). The accuracy of the sieves shall be
verified monthly against a set of master sieves kept for this purpose, using an accepted method such as
particle reference materials, microscopy, etc. (Reference [1] in the Bibliography) depending on the sieve
aperture. Tolerances shall meet the requirements of ISO 3310-1 and ISO 3310-2. Sieves that do not meet
these specifications shall be discarded. A record shall be kept of such testing.
Brass sieves are particularly liable to splitting and distortion, and steel sieves are strongly recommended for
the larger apertures.
Special care shall be taken to ensure that covers and receivers do not leak. Sieves shall be inspected weekly
when in regular use, and on every occasion if used less often. A record shall be kept of such inspections.
Round-hole sieves shall not be used.
4 © ISO 2009 – All rights reserved
7.2.2 Balance, capable of weighing to an accuracy of within ± 0,5 g.
7.2.3 Mechanical sieve shaker.
It is usually impracticable to sieve mechanically at sieve apertures much greater than 20 mm, unless very
heavy-duty equipment is available. Mechanical sieve shaking is essential to sieve efficiency at smaller
apertures.
7.2.4 A sieve brush and a stiff brush.
7.3 Procedure
Weigh the dry test sample, prepared in accordance with ISO 11464, to the nearest 0,5 g (m ). Place the
weighed material on the 20 mm sieve, and by brushing the material gently over the sieve apertures with the
stiff brush (to remove any adhering soil), sieve the material. Take care not to detach any fragments from the
primary particles. Sieve the retained material on the nest of sieves of selected apertures (7.2.1) and record the
amount retained on each sieve to the nearest 0,5 g. Do not overload the sieves (see Table 1), but sieve the
material in portions if necessary.
Weigh the material passing the 20 mm aperture sieve (m ), or a suitable portion of it (m ) (see Table 2)
2 3
obtained by an appropriate subsampling method (see Clause 6), and place this on a nest of sieves, the
lowermost having an aperture of 2 mm. Shake the sieves mechanically until no further material passes any of
the sieves (see note). Record the mass of material retained on each sieve and the mass passing the 2 mm
aperture sieve.
The total mass of the fractions should be within 1 % of m or m , as appropriate. If it is not, then check for
2 3
sieve damage and discard sieves as appropriate (see 7.2.1).
The sieve equipment performance should be verified against a suitable test material, e.g. standard particle
reference materials, ballotini, at intervals of one month. The results of this check shall be recorded.
NOTE For practical purposes, it is usual to choose a standard sieve shaking time which gives an acceptable degree
of sieving efficiency with a wide range of soil materials. The minimum recommended period is 10 min.
Table 1 — Mass of soil sample to be taken for sieving
Maximum size of material forming > 10 % of the soil Minimum mass of sample to be taken for sieving
(given as test sieve aperture, in mm) kg
63 50
50 35
37,5 15
28 6
20 2
14 1
10 0,5
6,3 0,5
5 0,2
2 or smaller 0,1
Table 2 — Maximum mass of material to be retained on each test sieve at the completion of sieving
Maximum mass
kg
Test sieve aperture
Sieve diameter
mm
mm 450 300 200
50 10 4,5
37,5 8 3,5
28 6 2,5
20 4 2,0
14 3 1,5
10 2 1,0
6,3 1,5 0,75
5 1,0 0,5
3,35 0,3
2 0,2
1,18 0,1
0,6 0,075
0,425 0,075
0,3 0,05
0,212 0,05
0,15 0,04
0,063 0,025
7.4 Calculation and expression of results
For the material retained by the 20 mm and larger aperture sieves, calculate the proportion by mass retained
by each sieve as a proportion of m . For example:
Proportion retained on the 20 mm sieve = [m(20 mm)]/m
For the material passing the 20 mm sieve, multiply the mass of material passing each sieve by m /m and
2 3
calculate this as a proportion of m . For example:
Proportion retained on the 6,3 mm sieve = m(6,3 mm)[(m /m )/m ]
2 3 1
Present the results as a table showing, to two significant figures, the proportion by mass retained on each
sieve and the proportion passing the 2 mm sieve. The data shall also be used to construct a cumulative
distribution curve (see Figure 1).
6 © ISO 2009 – All rights reserved
8 Wet sieving and sedimentation (material < 2 mm)
8.1 General
This clause specifies the procedure (see Figure 2) for the determination of the particle size distribution of the
material passing the 2 mm aperture sieve down to < 0,002 mm equivalent spherical diameter (see note). In
order to ensure that primary particles, rather than loosely bonded aggregates, are measured, organic matter
and salts are removed, especially sparingly soluble salts such as gypsum which would otherwise prevent
dispersion and/or promote flocculation of the finer soil particles in suspension (see 8.6), and a dispersing
agent is added (8.8). These procedures are required in this International Standard, and their omission shall
invalidate its application. Sometimes iron oxides and carbonates, especially of calcium and/or magnesium, are
also removed. Preferred procedures for the removal of these compounds are given in the note in 8.7. The
removal of any compound shall be recorded in the test report (Clause 10).
NOTE Gravitational sedimentation can give a value for the total amount of material < 0,002 mm equivalent spherical
diameter. However, the method cannot be used to divide this class further with reliability, as particles less than about
0,001 mm equivalent spherical diameter can be kept in suspension almost indefinitely by Brownian motion (Reference [1]
in the Bibliography).
8.2 Apparatus
The apparatus specified hereafter is sufficient to deal with one sample. Clearly it is more efficient to work in
batches. Experience has shown (Reference [6] in the Bibliography) that one operator can process up to
36 samples in a batch at a time, given sufficient apparatus and space, especially if calculations are dealt with
by a computer.
8.2.1 Sampling pipette, of a pattern similar to that shown in Figure 3, the chief requirement being that the
smallest practicable zone of sedimenting suspension shall be sampled. The pipette shall be of not less than
10 ml volume and shall be held in a frame so that it can be lowered to a fixed depth within a sedimentation
tube (see Figure 4).
NOTE Experience suggests that a pipette with an upper volume of 50 ml is more than sufficient for most purposes. A
25 ml volume pipette is a convenient compromise for routine analysis, but a smaller volume pipette will be found to be
sufficient for soils with down to about 10 % mass fraction of < 0,063 mm equivalent spherical diameter. Below this amount,
greater precision is likely to be obtained with a pipette of larger volume.
Figure 1 — Particle-size-distribution chart
8 © ISO 2009 – All rights reserved
Figure 2 — Flow chart
Dimensions in millimetres
Key
1 bulb capacity: approximately 125 ml
2 pipette and changeover cock capacity: ∼ 10 ml
NOTE This design has been found satisfactory, but alternative designs can be used.
Figure 3 — Sampling pipette for sedimentation test
10 © ISO 2009 – All rights reserved
Key
A and B 125 ml bulb funnel with stopcock
C safety-bulb suction inlet tube
D safety bulb
E tap
F outlet tube
G sampling pipette
H sedimentation tube
1 scale graduated in millimetres
2 clamps
3 sliding panel
4 constant-temperature bath
NOTE This design has been found satisfactory, but alternative designs can be used.
a
D, F and G are joined to three-way stopcock E.
Figure 4 — Arrangement for lowering sampling pipette into soil suspension
8.2.2 Constant-temperature room or bath, which can be maintained at between 20 °C and 30 °C ± 0,5 °C.
If a bath is used, it shall accept a sedimentation tube immersed to the 500 ml mark, and shall not vibrate the
contents of the tube. Similarly, if a room is used, it, and its furniture, shall be constructed so that activity does
not cause the tubes and their contents to vibrate.
NOTE This temperature range has been chosen to allow for the difficulties of maintaining one specified temperature
in different parts of the world. In addition, the lower temperature gives sedimentation times that fit well into an average
working day, whilst the upper temperature still allows for a sensible settling time for the fraction 0,063 mm equivalent
spherical diameter (see Clause 4 and Table 3).
Table 3 — Pipette sampling times and d (for a particle density of 2,65 Mg/m )
p
at a sampling depth of 100 mm ± 1 mm at different temperatures
Times, after mixing, of starting sampling operation
Temperature
a
1st sample 2nd sample 3rd sample 4th sample
°C
min s min s min s h min s
20 0 56 4 38 51 35 7 44 16
21 0 54 4 32 50 27 7 34 4
22 0 53 4 26 49 19 7 23 53
23 0 52 4 19 48 8 7 13 13
24 0 51 4 13 47 0 7 3 2
25 0 49 4 7 45 52 6 52 50
26 0 48 4 2 44 53 6 44 2
27 0 47 3 57 43 58 6 35 42
28 0 46 3 52 42 59 6 26 53
29 0 45 3 47 42 3 6 18 33
30 0 44 3 41 41 5 6 9 45
d(mm) 0,063 0,020 0,006 0,002
p
a
Sampling depth 200 mm ± 1 mm to allow adequate time for the stabilization of the suspension after mixing.
8.2.3 Two glass sedimentation tubes, without pouring lips, of internal diameter approximately 50 mm, and
overall length 350 mm, graduated at 500 ml volume, and with either rubber bungs to fit or a stirrer.
8.2.4 Stirrer, of noncorrodible material, as in Figure 5.
8.2.5 Five glass weighing vessels, with masses known to the nearest 0,000 1 g.
8.2.6 Mechanical shaker, capable of keeping 30 g of soil in suspension in 150 ml of liquid. A device which
rotates the container end-over-end at 30 revolutions/min to 60 revolutions/min is suitable. The vigorous
end-to-end type of shaker and the horizontal rotary shaker are both unsuitable, and neither shall be used (see
the note in 8.9).
8.2.7 Test sieves, complying with ISO 565, ISO 3310-1 and ISO 3310-2, having apertures of 2 mm and
0,063 mm, plus two intermediate sieves. The test report shall state which apertures are used. Round-hole
sieves shall not be used.
NOTE The choice of the sieve of aperture 0,063 mm given here is for illustration, but accords with the widespread
use of this particle size to define the upper boundary of the silt fraction. Local requirements can specify another aperture.
The choice of apertures for the intermediate sieves is a matter for local knowledge, but experience suggests that sieves of
aperture close to 0,2 mm and 0,1 mm are useful for a very wide range of soils.
12 © ISO 2009 – All rights reserved
Dimensions in millimetres
Prepare a stirrer as shown, suitable materials being
a) brass or aluminium,
b) poly,(methy/methacrylate), or
c) a section of a rubber stopper fitted onto a glass rod, etc.
Figure 5 — Example of stirrer; perforated stopper fitted onto glass rod
8.2.8 Suitable sample divider (Clause 6).
8.2.9 Balance, capable of weighing to an accuracy of within ± 0,000 1 g.
8.2.10 Drying oven, capable of maintaining a temperature between 105 °C and 110 °C.
8.2.11 Stop clock, readable to 1 s.
8.2.12 Desiccator, containing anhydrous silica gel (preferably of the self-indicating type), capable of holding
the five weighing vessels. The desiccant shall be inspected daily and dried at between 105 °C and 110 °C
when it is no longer effective.
8.2.13 Tall-form glass beaker, of capacity 650 ml with a cover glass to fit, or a 300 ml centrifuge bottle
with a leakproof cap.
NOTE This apparatus is used for chemical pretreatment, during which a constant problem is the adhesion of very fine
particles to glass. The problem is much reduced if the treatment is carried out in a polycarbonate or polysulfone centrifuge
bottle. Both materials will withstand repeated heating to 120 °C and are resistant to hydrogen peroxide and common
dispersing agents. Their use can also save significant amounts of operator time.
8.2.14 Centrifuge, capable of holding the 300 ml centrifuge bottles (see 8.8).
8.2.15 Measuring cylinder, of capacity 100 ml.
8.2.16 Pipette, of capacity 25 ml.
8.2.17 Glass filter funnel, capable of holding the 0,063 mm sieve.
8.2.18 Wash bottle containing water (see 8.3).
8.2.19 Rod, of glass or strong plastic, 150 mm to 200 mm long and at least 4 mm in diameter, with a rubber
sleeve at one end.
8.2.20 Electric hotplate, capable of maintaining a temperature between 105 °C and 110 °C.
NOTE A hotplate is essential if polymer centrifuge bottles are used for the chemical pretreatment, but a Bunsen
burner, gauze and tripod are sufficient if glass beakers are used.
8.2.21 Suction device, similar to that shown in Figure 6 is useful, but not essential.
Key
1 flexible tube
2 Pasteur pipette or similar
3 reservoir (5 l or 10 l)
a
To vacuum.
Figure 6 — Sketch of suction device
8.2.22 Sieve brush.
8.2.23 Electrical conductivity meter, accurate to 0,1 dS/m.
14 © ISO 2009 – All rights reserved
8.3 Reagents
All reagents shall be of recognized analytical grade. Use water conforming to Class 2 of ISO 3696, i.e. having
an electrical conductivity no greater than 0,1 dS/m at 25 °C at the time of use.
8.3.1 Hydrogen peroxide solution, 30 % volume fraction.
NOTE A 30 % volume fraction solution is one which will yield 30 ml of gaseous oxygen from 100 ml of solution (under
standard conditions of temperature and pressure) upon reduction to water, either by chemical means or by boiling.
8.3.2 Solution of a dispersing agent.
The most widely used dispersing agent is that prepared by dissolving 33 g of sodium hexametaphosphate and
7 g of anhydrous sodium carbonate in water to make 1 L of solution. This is the preferred dispersant. Store
away from strong sunlight and preferably in a dark bottle. Record the date of preparation on the bottle. The
solution is unstable and shall be replaced after one month.
Buffered sodium hexametaphosphate is commonly referred to in the literature as “Calgon”. This is a trade
name. The substance sold as such is often not the reagent described in this subclause, is of variable
composition, and shall not be used as a dispersing agent in the method given in this International Standard
(Reference [8] in the Bibliography).
It is permissible to use other dispersing agents (see the last paragraph of this subclause), the choice of which
shall be recorded in the test report (Clause 10). Whichever dispersant proves to be the most suitable for a
particular soil, it is essential that the suspension be examined visually to ensure that effective dispersion has
occurred and that the dispersed suspension is stable, i.e. that no flocculation has occured or is occurring. This
inspection shall be carried out for each and every sample.
The sodium carbonate buffers the solution, and the suspension of the soil, to about pH 9,8. This dispersing
agent has been found successful with a very wide range of soils. However, if there are signs that dispersion is
ineffective, consider firstly that flocculating salts might be present (see 8.7). If dispersion is still unsuccessful
after removal of salts, then other dispersing agents should be considered. A very effective but less widely
used dispersing agent is prepared by replacing the sodium carbonate with 20 % volume fraction ammonia
solution, in the ratio of 5 ml ammonia solution to 150 ml of the hexametaphosphate solution. There are many
other dispersing agents (Reference [2] in the Bibliography). Whichever is chosen, considerable investigation
will be required to establish its effectiveness. It should be remembered that some soils show fewer problems
of dispersion if analysed without drying (see Annex A). Some soils derived from recent volcanic deposits will
disperse more effectively in an acid medium (Reference [9] in the Bibliography).
8.3.3 Octan-2-ol, or a similar volatile antifoaming agent.
NOTE Octan-2-ol is highly effective and relatively long-lasting. Ethanol or methanol can also be used, but the use of
pentan-2-ol (amyl alcohol) is discouraged because it is potentially addictive.
8.4 Calibrations
8.4.1 Sampling pipette (Figure 4)
Clean and dry the pipette thoroughly and immerse the tip in water held at the same temperature as that of the
constant-temperature environment (8.2.2). By means of a tube attached to C, draw water into the pipette
above E. Drain off the water above E through F. Drain the pipette into a weighing bottle of known mass and
determine the new mass. From the known masses, calculate the internal volume of the pipette. Repeat this
exercise three times and take the average of the three volumes as the internal volume of the pipette to the
nearest 0,05 ml (V ml).
c
8.4.2 Dispersing-agent correction
Follow this procedure each time a new batch of dispersing agent is prepared.
Pipette 25 ml of dispersing-agent solution into one of the glass sedimentation tubes, and fill the tube to the
500 ml mark with water. Mix the contents of the tube thoroughly. Place the tube in the constant-temperature
environment, and leave the tube for at least 1 h. Between any of the times at which samples may be taken
from the sampling tube (Table 3), take a sample (V ml) of the dispersing-agent solution from the
c
sedimentation tube using the sampling pipette. Drain the pipette into a weighing vessel of known mass, and
dry the contents of the vessel between 105 °C and 110 °C. Allow the vessel to cool in the desiccator and
determine the mass of the residue in the vessel to 0,000 1 g (m ).
r
The minimum temperature equilibration period in the water bath is 1 h, but if a large number of tubes is placed
in a bath, equilibration will take at least 4 h. In such cases, it is advantageous to arrange the work so that
equilibration takes place overnight. Equilibration will be quicker if the supply of water used to fill up the tubes is
kept at or near the same temperature as the constant-temperature environment.
8.5 Test sample
The test sample shall be taken from the material passing a 2 mm aperture sieve (see Clause 6 and 7.2) and
weighed to the nearest 0,001 g (m ). The mass of test sample depends on the type of soil. Approximately 30 g
s
for a sandy soil and 10 g for a clay soil are appropriate for pipette analysis, with proportionate masses for soils
intermediate to these extremes. For the hydrometer method (Annex B), take twice this amount of material.
Place the test sample in either the 650 ml glass beaker or the 300 ml centrifuge bottle (8.2.13 and its note).
Highly organic soils contain relatively little mineral matter. It might be necessary to take up to 100 g of such
soils in order to obtain sufficient mineral matter for a reliable analysis of the particle size distribution of this
component. Such a large amount of organic material should be apportioned between several vessels for ease
of operation, with combination of the mineral residues at a later stage.
8.6 Destruction of organic matter
Destroy the organic matter with hydrogen peroxide solution as follows. Add approximately 30 ml of water to
the test sample and allow it to become thoroughly wet (see Note 1 below). Add 30 ml of 30 % volume fraction
hydrogen peroxide solution and mix the contents of the vessel very gently using the glass or plastic rod. A
vigorous reaction can cause foaming of the sample mixture. This can be controlled by adding a few millilitres
of octan-2-ol. Allow any vigorous reaction to subside.
WARNING — Carry out this step with caution. Hydrogen peroxide can decompose violently with some
forms of organic matter, manganese compounds and finely-particulate iron sulfides, all of which can
occur in soil. Do not examine the reaction by looking into the top of the vessel. Do not accelerate an
apparently slow reaction by heating or addition of more hydrogen peroxide.
If using the 650 ml beaker, cover with the cover glass and leave overnight. Place the vessel on the hotplate or
Bunsen burner, as appropriate (8.2.20), and warm gently. Control any foaming with octan-2-ol as before, and
stir the contents frequently. Do not allow the contents to dry out, adding more water if necessary. Bring the
suspension to a gentle boil and heat until all signs of bubbling due to decomposition of hydrogen peroxide
have ceased. If there is still-undecomposed organic matter, remove the vessel from the heat, allow it to cool
and repeat the treatment with hydrogen peroxide. Highly organic soils will need several such treatments, the
products of the reaction being removed after every 2 or 3 treatments before continuing with more peroxide.
If destruction of organic matter has been carried out in a centrifuge bottle, bring the volume of the contents to
between 150 ml and 200 ml by addition of water. If a glass beaker has been used, then transfer the contents
to a centrifuge bottle, taking care to remove all traces of material from the sides of the beaker by means of the
rubber sleeve on the glass or plastic rod. Again, the final volume should be 150 ml to 200 ml. Centrifuge the
bottle so as to obtain a clear supernatant [15 min at a minimum relative centrifugal force (RCF) of 400g is
recommended], and decant the latter or remove by means of the suction device. Repeat the treatment until
the supernatant is colourless or nearly so.
16 © ISO 2009 – All rights reserved
NOTE 1 Dry organic materials are often strongly hydrophobic, in which case the addition of a few drops of octan-2-ol
can be beneficial.
If a centrifuge is not available, the mineral residues may be flocculated by adding 25 ml of 1 mol/l calcium
chloride solution. Stir thoroughly, bring to about 250 ml with water, allow to stand until the supernatant is clear,
then siphon or decant this from the residue. Add another 250 ml of water and repeat the washing procedure
until the dark residues of the decomposed organic matter have gone. Check that the electrical conductivity of
the washings is below 0,4 dS/m before attempting to disperse the residue (see 8.8).
Another alternative is to filter the residue from the oxidation step on a hardened, high wet-strength filter paper
(2,7 µm pore size is suitable), followed by thorough washing with water by means of the wash-bottle. It is
essential to observe the filtrate closely to see that no soil is lost. If particles pass through the filter paper,
return the filtrate to the container, add calcium chloride solution to the suspension as above, stir and refilter.
If flocculation with calcium chloride, or filtration, are ineffective in preventing the loss of fine soil particles, then
a few drops of a 60 g/l aluminium sulfate solution can be stirred into the soil suspension. The absolute
minimum of aluminium sulfate shall be used, as excess could cause problems in the subsequent dispersion of
the soil.
NOTE 2 Lignified (woody) residues of plants are extremely difficult to decompose, and their complete destruction is
often impossible. Such fragments are usually regarded as decomposed when they have lost all traces of dark colour.
Transfer the washed residue quantitatively to a centrifuge bottle. In all cases, it is not essential for the
supernatant to be absolutely colourless, so long as it is obvious that the bulk of the dark decomposition
products of the organic matter have been removed, but the solution shall be clear. The use of calcium chloride
solution or aluminium sulfate solution, in conjunction with f
...
SLOVENSKI STANDARD
01-maj-2011
1DGRPHãþD
SIST ISO 11277:2006
SIST ISO 11277:2006/Cor 1:2006
.DNRYRVWWDO'RORþHYDQMHSRUD]GHOLWYHYHOLNRVWLGHOFHYYPLQHUDOQHPGHOXWDO
0HWRGDVVHMDQMHPLQXVHGDQMHP
Soil quality - Determination of particle size distribution in mineral soil material - Method
by sieving and sedimentation
Qualité du sol - Détermination de la répartition granulométrique de la matière minérale
des sols - Méthode par tamisage et sédimentation
Ta slovenski standard je istoveten z: ISO 11277:2009
ICS:
13.080.20 Fizikalne lastnosti tal Physical properties of soils
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 11277
Second edition
2009-09-15
Soil quality — Determination of particle
size distribution in mineral soil
material — Method by sieving and
sedimentation
Qualité du sol — Détermination de la répartition granulométrique de la
matière minérale des sols — Méthode par tamisage et sédimentation
Reference number
©
ISO 2009
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ii © ISO 2009 – All rights reserved
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terminology and symbols.2
4 Principle.2
5 Field sampling .4
6 Sample preparation .4
7 Dry sieving (material > 2 mm).4
8 Wet sieving and sedimentation (material < 2 mm) .7
9 Precision.20
10 Test report.21
Annex A (normative) Determination of particle size distribution of mineral soil material that is not
dried prior to analysis.22
Annex B (normative) Determination of particle size distribution of mineral soils by a hydrometer
method following destruction of organic matter .25
Bibliography.34
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11277 was prepared by Technical Committee ISO/TC 190, Soil quality.
This second edition cancels and replaces the first edition (ISO 11277:1998), of which it constitutes a minor
revision, and incorporates ISO 11277:1998/Cor.1:2002.
iv © ISO 2009 – All rights reserved
Introduction
The physical and chemical behaviour of soils is controlled in part by the amounts of mineral particles of
different sizes in the soil. The subject of this International Standard is the quantitative measurement of such
amounts (expressed as a proportion or percentage of the total mass of the mineral soil), within stated size
classes.
The determination of particle size distribution is affected by organic matter, soluble salts, cementing agents
(especially iron compounds), relatively insoluble substances such as carbonates and sulfates, or combinations
of these. Some soils change their behaviour to such a degree, upon drying, that the particle size distribution of
the dried material bears little or no relation to that of the undried material encountered under natural conditions.
This is particularly true of soils rich in organic matter, those developed from recent volcanic deposits, some
highly weathered tropical soils, and soils often described as “cohesive” (Reference [3] in the Bibliography).
Other soils, such as the so-called “sub-plastic” soils of Australia, show little or no tendency to disperse under
normal laboratory treatments, despite field evidence of a large clay content.
The procedures given in this International Standard recognize these kinds of differences between soils from
different environments, and the methodology presented is designed to deal with them in a structured manner.
Such differences in soil behaviour can be very important, but awareness of them depends usually on local
knowledge. Given that the laboratory is commonly distant from the site of the field operation, the information
supplied by field teams becomes crucial to the choice of an appropriate laboratory procedure. This choice can
be made only if the laboratory is made fully aware of this background information.
INTERNATIONAL STANDARD ISO 11277:2009(E)
Soil quality — Determination of particle size distribution in
mineral soil material — Method by sieving and sedimentation
WARNING — All procedures in this International Standard must be carried out by competent, trained
persons, with adequate supervision. Attention is drawn to certain known hazards, but it is essential
that users follow safe working practices. If in any doubt, seek professional advice.
It is essential that users of this International Standard read all of it before commencing any operation,
as failure to note certain points will lead to incorrect analysis and could be dangerous.
1 Scope
This International Standard specifies a basic method of determining the particle size distribution applicable to
a wide range of mineral soil materials, including the mineral fraction of organic soils. It also offers procedures
to deal with the less common soils mentioned in the introduction. This International Standard has been
developed largely for use in the field of environmental science, and its use in geotechnical investigations is
something for which professional advice might be required.
A major objective of this International Standard is the determination of enough size fractions to enable the
construction of a reliable particle-size-distribution curve.
This International Standard does not apply to the determination of the particle size distribution of the organic
components of soil, i.e. the more or less fragile, partially decomposed, remains of plants and animals. It is also
realized that the chemical pretreatments and mechanical handling stages in this International Standard could
cause disintegration of weakly cohesive particles that, from field inspection, might be regarded as primary
particles, even though such primary particles could be better described as aggregates. If such disintegration is
undesirable, then this International Standard is not used for the determination of the particle size distribution of
such weakly cohesive materials.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 565:1990, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal
sizes of openings
ISO 3310-1:2000, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3310-2:1999, Test sieves — Technical requirements and testing — Part 2: Test sieves of perforated
metal plate
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods
ISO 11464:2006, Soil quality — Pretreatment of samples for physico-chemical analysis
3 Terminology and symbols
3.1 Terminology
Particles within particular size ranges or classes are commonly described as cobbles, gravel, coarse sand, silt,
etc. The meaning of such trivial names differs between countries, and in some cases there are no exact
translations of such words from one language to another; for example, the Dutch word “zavel” has no
equivalent in English. The only fraction for which there appears to be common agreement is clay, which is
defined as material of less than 0,002 mm equivalent spherical diameter (References [1, 3] in the
Bibliography). Such trivial names shall not be used in describing the results of particle size determination
according to this International Standard. Phrases such as “. passing a 20 mm aperture sieve .” or “. less
then 0,063 mm equivalent spherical diameter .” shall be used instead. If trivial names must be used, for
example, to cross-reference to another International or National Standard, then the trivial name should be
defined explicitly, so as to remove any doubt as to the meaning intended, e.g. silt (0,063 mm to 0,002 mm
equivalent spherical diameter) (see Clause 4). Furthermore, it is common to use the word “texture” to describe
the results of particle-size-distribution measurements, e.g. “the particle size of this soil is of clay texture”. This
is incorrect as the two concepts are different, and the word “texture” shall not be used in the test report
(Clause 10) to describe the results obtained by the use of this International Standard.
It is common to refer to sieves as having a particular mesh-size or mesh number. These are not the same as
the sieve aperture, and the relationship between the various numbers is not immediately obvious. The use of
mesh numbers as a measurement of particle size is difficult to justify, and shall not be used in reporting the
results of this International Standard.
3.2 Symbols
The following symbols are found throughout the text and, where appropriate, units and quantities are as given
below (the SI convention is followed for common units, e.g. g = gram; m = metre; mm = millimetre; s = second,
etc.).
Mg megagram (10 g);
mPa millipascal;
t is the settling time, in seconds, of a particle of diameter d ;
p
η is the dynamic viscosity of water at the test temperature (see Table B.2), in millipascals per second;
h is the sampling depth, in centimetres;
ρ is the mean particle density, in megagrams per cubic metre (taken as 2,65 Mg/m ; see the note in
s
Clause 4);
ρ is the density of the liquid containing the soil suspension, in megagrams per cubic metre (taken as
w
1,00 Mg/m ; see the note in Clause 4);
g is the acceleration due to gravity, in centimetres per second squared (taken as 981 cm/s );
d is the equivalent spherical diameter of the particle of interest, in millimetres.
p
4 Principle
The particle size distribution is determined by a combination of sieving and sedimentation, starting from air-
dried soil (Reference [3] in the Bibliography) (see note below). A method for undried soil is given in Annex A.
Particles not passing a 2 mm aperture sieve are determined by dry sieving. Particles passing such a sieve, but
retained on a 0,063 mm aperture sieve, are determined by a combination of wet and dry sieving, whilst
2 © ISO 2009 – All rights reserved
particles passing the latter sieve are determined by sedimentation. The pipette method is preferred. A
hydrometer method is given in Annex B. A combination of sieving and sedimentation enables the construction
of a continuous particle-size-distribution curve.
The key points in this procedure are summarized as a flow chart in Figure 2. This International Standard
requires that the proportions of fractions separated by sedimentation and sieving be determined from the
masses of such fractions obtained by weighing. Other methods of determining the mass of such fractions rely
on such things as the interaction of particles with electromagnetic radiation or electrical fields (Reference [1] in
the Bibliography). There are often considerable difficulties in relating the values obtained by these different
methods for the same sample. It is one of the intentions of this International Standard that close adherence to
its details should help minimize interlaboratory variation in the determination of the particle size distribution of
mineral soils. Therefore, the proportions of fractions shall be determined only by weighing. If this is not the
method used, then compliance with this International Standard cannot be claimed in the test report
(Clause 10).
Both the pipette and hydrometer methods assume that the settling of particles in the sedimentation cylinder is
in accordance with Stokes's Law (References [1, 3, 6] in the Bibliography), and the constraints that this
implies, namely:
a) the particles are rigid, smooth spheres;
b) the particles settle in laminar flow, i.e. the Reynolds Number is less than about 0,2; this constraint sets an
upper equivalent spherical particle diameter (see below) slightly greater than 0,06 mm for Stokesian
settling under gravity (Reference [1] in the Bibliography);
c) the suspension of particles is sufficiently dilute to ensure that no particle interferes with the settling of any
other particle;
d) there is no interaction between the particle and fluid;
e) the diameter of the suspension column is large compared to the diameter of the particle, i.e. the fluid is of
“infinite extent”;
f) the particle has reached its terminal velocity;
g) the particles are of the same relative density.
Thus, the diameter of a particle is defined in terms of the diameter of a sphere whose behaviour in suspension
matches that of the particle. This is the concept of equivalent spherical diameter. It is the principle upon which
the expression of the diameter of particles, as derived from sedimentation, is based in this International
Standard.
Stokes's Law can be written, for the purposes of this International Standard, in the form:
⎡⎤
th=−18ηρ ρgd
()
sw p
⎣⎦
where
t is the settling time, in seconds, of a particle of diameter d (see below);
p
η is the dynamic viscosity of water at the test temperature (see Table B.2), in millipascals per second;
h is the sampling depth, in centimetres;
ρ is the mean particle density, in megagrams per cubic metre (taken as 2,65 Mg/m ; see note);
s
ρ is the density of the liquid containing the soil suspension, in megagrams per cubic metre (taken as
w
1,00 Mg/m ; see note);
g is the acceleration due to gravity, in centimetres per second squared (taken as 981 cm/s );
d is the equivalent spherical diameter of the particle of interest, in millimetres.
p
NOTE It is realized that there are considerable differences between the densities of soil particles, but for the
purposes of this International Standard it is assumed that the mean particle density is that of quartz, i.e. 2,65 Mg/m
(Reference [7] in the Bibliography), as this is the commonest mineral in a very wide range of soils. The density of water is
3 3
0,998 2 Mg/m and 0,995 6 Mg/m at 20 °C and 30 °C, respectively (Reference [5] in the Bibliography). Given the effect of
the addition of a small amount of dispersant (see 8.3.2), the density of water is taken as 1,000 0 Mg/m over the permitted
temperature range of this International Standard (8.2.2).
Furthermore, for routine use, it is recommended that the sampling times be converted to minutes and/or hours,
as appropriate, to lessen the risk of error (see Table 3).
5 Field sampling
The mass of sample taken in the field shall be representative of the particle size distribution, especially if the
amount of the larger particles is to be determined reliably. Table 1 gives recommended minimum masses.
6 Sample preparation
Samples shall be prepared in accordance with the methods given in ISO 11464.
NOTE For many purposes, particle size distribution is determined only for the fraction of the soil passing a 2 mm
aperture sieve. In this case, the test sample (8.5) can be taken either according to the procedures in ISO 11464 or from
the material passing a 2 mm aperture sieve according to 7.2.
7 Dry sieving (material > 2 mm)
7.1 General
The procedure specified in this clause applies to material retained on a 2 mm aperture sieve. Table 2 gives
the maximum mass which shall be retained on sieves of different diameters and apertures. If more than this
amount of material is retained, then it shall be subdivided appropriately and resieved.
7.2 Apparatus
7.2.1 Test sieves, with apertures which comply with ISO 565, and with well-fitting covers and receivers.
The full range of sieves appropriate to the largest particle(s) present should be used (see Table 1 and 7.2.3).
The apertures chosen shall be stated in the test report (Clause 10). The accuracy of the sieves shall be
verified monthly against a set of master sieves kept for this purpose, using an accepted method such as
particle reference materials, microscopy, etc. (Reference [1] in the Bibliography) depending on the sieve
aperture. Tolerances shall meet the requirements of ISO 3310-1 and ISO 3310-2. Sieves that do not meet
these specifications shall be discarded. A record shall be kept of such testing.
Brass sieves are particularly liable to splitting and distortion, and steel sieves are strongly recommended for
the larger apertures.
Special care shall be taken to ensure that covers and receivers do not leak. Sieves shall be inspected weekly
when in regular use, and on every occasion if used less often. A record shall be kept of such inspections.
Round-hole sieves shall not be used.
4 © ISO 2009 – All rights reserved
7.2.2 Balance, capable of weighing to an accuracy of within ± 0,5 g.
7.2.3 Mechanical sieve shaker.
It is usually impracticable to sieve mechanically at sieve apertures much greater than 20 mm, unless very
heavy-duty equipment is available. Mechanical sieve shaking is essential to sieve efficiency at smaller
apertures.
7.2.4 A sieve brush and a stiff brush.
7.3 Procedure
Weigh the dry test sample, prepared in accordance with ISO 11464, to the nearest 0,5 g (m ). Place the
weighed material on the 20 mm sieve, and by brushing the material gently over the sieve apertures with the
stiff brush (to remove any adhering soil), sieve the material. Take care not to detach any fragments from the
primary particles. Sieve the retained material on the nest of sieves of selected apertures (7.2.1) and record the
amount retained on each sieve to the nearest 0,5 g. Do not overload the sieves (see Table 1), but sieve the
material in portions if necessary.
Weigh the material passing the 20 mm aperture sieve (m ), or a suitable portion of it (m ) (see Table 2)
2 3
obtained by an appropriate subsampling method (see Clause 6), and place this on a nest of sieves, the
lowermost having an aperture of 2 mm. Shake the sieves mechanically until no further material passes any of
the sieves (see note). Record the mass of material retained on each sieve and the mass passing the 2 mm
aperture sieve.
The total mass of the fractions should be within 1 % of m or m , as appropriate. If it is not, then check for
2 3
sieve damage and discard sieves as appropriate (see 7.2.1).
The sieve equipment performance should be verified against a suitable test material, e.g. standard particle
reference materials, ballotini, at intervals of one month. The results of this check shall be recorded.
NOTE For practical purposes, it is usual to choose a standard sieve shaking time which gives an acceptable degree
of sieving efficiency with a wide range of soil materials. The minimum recommended period is 10 min.
Table 1 — Mass of soil sample to be taken for sieving
Maximum size of material forming > 10 % of the soil Minimum mass of sample to be taken for sieving
(given as test sieve aperture, in mm) kg
63 50
50 35
37,5 15
28 6
20 2
14 1
10 0,5
6,3 0,5
5 0,2
2 or smaller 0,1
Table 2 — Maximum mass of material to be retained on each test sieve at the completion of sieving
Maximum mass
kg
Test sieve aperture
Sieve diameter
mm
mm 450 300 200
50 10 4,5
37,5 8 3,5
28 6 2,5
20 4 2,0
14 3 1,5
10 2 1,0
6,3 1,5 0,75
5 1,0 0,5
3,35 0,3
2 0,2
1,18 0,1
0,6 0,075
0,425 0,075
0,3 0,05
0,212 0,05
0,15 0,04
0,063 0,025
7.4 Calculation and expression of results
For the material retained by the 20 mm and larger aperture sieves, calculate the proportion by mass retained
by each sieve as a proportion of m . For example:
Proportion retained on the 20 mm sieve = [m(20 mm)]/m
For the material passing the 20 mm sieve, multiply the mass of material passing each sieve by m /m and
2 3
calculate this as a proportion of m . For example:
Proportion retained on the 6,3 mm sieve = m(6,3 mm)[(m /m )/m ]
2 3 1
Present the results as a table showing, to two significant figures, the proportion by mass retained on each
sieve and the proportion passing the 2 mm sieve. The data shall also be used to construct a cumulative
distribution curve (see Figure 1).
6 © ISO 2009 – All rights reserved
8 Wet sieving and sedimentation (material < 2 mm)
8.1 General
This clause specifies the procedure (see Figure 2) for the determination of the particle size distribution of the
material passing the 2 mm aperture sieve down to < 0,002 mm equivalent spherical diameter (see note). In
order to ensure that primary particles, rather than loosely bonded aggregates, are measured, organic matter
and salts are removed, especially sparingly soluble salts such as gypsum which would otherwise prevent
dispersion and/or promote flocculation of the finer soil particles in suspension (see 8.6), and a dispersing
agent is added (8.8). These procedures are required in this International Standard, and their omission shall
invalidate its application. Sometimes iron oxides and carbonates, especially of calcium and/or magnesium, are
also removed. Preferred procedures for the removal of these compounds are given in the note in 8.7. The
removal of any compound shall be recorded in the test report (Clause 10).
NOTE Gravitational sedimentation can give a value for the total amount of material < 0,002 mm equivalent spherical
diameter. However, the method cannot be used to divide this class further with reliability, as particles less than about
0,001 mm equivalent spherical diameter can be kept in suspension almost indefinitely by Brownian motion (Reference [1]
in the Bibliography).
8.2 Apparatus
The apparatus specified hereafter is sufficient to deal with one sample. Clearly it is more efficient to work in
batches. Experience has shown (Reference [6] in the Bibliography) that one operator can process up to
36 samples in a batch at a time, given sufficient apparatus and space, especially if calculations are dealt with
by a computer.
8.2.1 Sampling pipette, of a pattern similar to that shown in Figure 3, the chief requirement being that the
smallest practicable zone of sedimenting suspension shall be sampled. The pipette shall be of not less than
10 ml volume and shall be held in a frame so that it can be lowered to a fixed depth within a sedimentation
tube (see Figure 4).
NOTE Experience suggests that a pipette with an upper volume of 50 ml is more than sufficient for most purposes. A
25 ml volume pipette is a convenient compromise for routine analysis, but a smaller volume pipette will be found to be
sufficient for soils with down to about 10 % mass fraction of < 0,063 mm equivalent spherical diameter. Below this amount,
greater precision is likely to be obtained with a pipette of larger volume.
Figure 1 — Particle-size-distribution chart
8 © ISO 2009 – All rights reserved
Figure 2 — Flow chart
Dimensions in millimetres
Key
1 bulb capacity: approximately 125 ml
2 pipette and changeover cock capacity: ∼ 10 ml
NOTE This design has been found satisfactory, but alternative designs can be used.
Figure 3 — Sampling pipette for sedimentation test
10 © ISO 2009 – All rights reserved
Key
A and B 125 ml bulb funnel with stopcock
C safety-bulb suction inlet tube
D safety bulb
E tap
F outlet tube
G sampling pipette
H sedimentation tube
1 scale graduated in millimetres
2 clamps
3 sliding panel
4 constant-temperature bath
NOTE This design has been found satisfactory, but alternative designs can be used.
a
D, F and G are joined to three-way stopcock E.
Figure 4 — Arrangement for lowering sampling pipette into soil suspension
8.2.2 Constant-temperature room or bath, which can be maintained at between 20 °C and 30 °C ± 0,5 °C.
If a bath is used, it shall accept a sedimentation tube immersed to the 500 ml mark, and shall not vibrate the
contents of the tube. Similarly, if a room is used, it, and its furniture, shall be constructed so that activity does
not cause the tubes and their contents to vibrate.
NOTE This temperature range has been chosen to allow for the difficulties of maintaining one specified temperature
in different parts of the world. In addition, the lower temperature gives sedimentation times that fit well into an average
working day, whilst the upper temperature still allows for a sensible settling time for the fraction 0,063 mm equivalent
spherical diameter (see Clause 4 and Table 3).
Table 3 — Pipette sampling times and d (for a particle density of 2,65 Mg/m )
p
at a sampling depth of 100 mm ± 1 mm at different temperatures
Times, after mixing, of starting sampling operation
Temperature
a
1st sample 2nd sample 3rd sample 4th sample
°C
min s min s min s h min s
20 0 56 4 38 51 35 7 44 16
21 0 54 4 32 50 27 7 34 4
22 0 53 4 26 49 19 7 23 53
23 0 52 4 19 48 8 7 13 13
24 0 51 4 13 47 0 7 3 2
25 0 49 4 7 45 52 6 52 50
26 0 48 4 2 44 53 6 44 2
27 0 47 3 57 43 58 6 35 42
28 0 46 3 52 42 59 6 26 53
29 0 45 3 47 42 3 6 18 33
30 0 44 3 41 41 5 6 9 45
d(mm) 0,063 0,020 0,006 0,002
p
a
Sampling depth 200 mm ± 1 mm to allow adequate time for the stabilization of the suspension after mixing.
8.2.3 Two glass sedimentation tubes, without pouring lips, of internal diameter approximately 50 mm, and
overall length 350 mm, graduated at 500 ml volume, and with either rubber bungs to fit or a stirrer.
8.2.4 Stirrer, of noncorrodible material, as in Figure 5.
8.2.5 Five glass weighing vessels, with masses known to the nearest 0,000 1 g.
8.2.6 Mechanical shaker, capable of keeping 30 g of soil in suspension in 150 ml of liquid. A device which
rotates the container end-over-end at 30 revolutions/min to 60 revolutions/min is suitable. The vigorous
end-to-end type of shaker and the horizontal rotary shaker are both unsuitable, and neither shall be used (see
the note in 8.9).
8.2.7 Test sieves, complying with ISO 565, ISO 3310-1 and ISO 3310-2, having apertures of 2 mm and
0,063 mm, plus two intermediate sieves. The test report shall state which apertures are used. Round-hole
sieves shall not be used.
NOTE The choice of the sieve of aperture 0,063 mm given here is for illustration, but accords with the widespread
use of this particle size to define the upper boundary of the silt fraction. Local requirements can specify another aperture.
The choice of apertures for the intermediate sieves is a matter for local knowledge, but experience suggests that sieves of
aperture close to 0,2 mm and 0,1 mm are useful for a very wide range of soils.
12 © ISO 2009 – All rights reserved
Dimensions in millimetres
Prepare a stirrer as shown, suitable materials being
a) brass or aluminium,
b) poly,(methy/methacrylate), or
c) a section of a rubber stopper fitted onto a glass rod, etc.
Figure 5 — Example of stirrer; perforated stopper fitted onto glass rod
8.2.8 Suitable sample divider (Clause 6).
8.2.9 Balance, capable of weighing to an accuracy of within ± 0,000 1 g.
8.2.10 Drying oven, capable of maintaining a temperature between 105 °C and 110 °C.
8.2.11 Stop clock, readable to 1 s.
8.2.12 Desiccator, containing anhydrous silica gel (preferably of the self-indicating type), capable of holding
the five weighing vessels. The desiccant shall be inspected daily and dried at between 105 °C and 110 °C
when it is no longer effective.
8.2.13 Tall-form glass beaker, of capacity 650 ml with a cover glass to fit, or a 300 ml centrifuge bottle
with a leakproof cap.
NOTE This apparatus is used for chemical pretreatment, during which a constant problem is the adhesion of very fine
particles to glass. The problem is much reduced if the treatment is carried out in a polycarbonate or polysulfone centrifuge
bottle. Both materials will withstand repeated heating to 120 °C and are resistant to hydrogen peroxide and common
dispersing agents. Their use can also save significant amounts of operator time.
8.2.14 Centrifuge, capable of holding the 300 ml centrifuge bottles (see 8.8).
8.2.15 Measuring cylinder, of capacity 100 ml.
8.2.16 Pipette, of capacity 25 ml.
8.2.17 Glass filter funnel, capable of holding the 0,063 mm sieve.
8.2.18 Wash bottle containing water (see 8.3).
8.2.19 Rod, of glass or strong plastic, 150 mm to 200 mm long and at least 4 mm in diameter, with a rubber
sleeve at one end.
8.2.20 Electric hotplate, capable of maintaining a temperature between 105 °C and 110 °C.
NOTE A hotplate is essential if polymer centrifuge bottles are used for the chemical pretreatment, but a Bunsen
burner, gauze and tripod are sufficient if glass beakers are used.
8.2.21 Suction device, similar to that shown in Figure 6 is useful, but not essential.
Key
1 flexible tube
2 Pasteur pipette or similar
3 reservoir (5 l or 10 l)
a
To vacuum.
Figure 6 — Sketch of suction device
8.2.22 Sieve brush.
8.2.23 Electrical conductivity meter, accurate to 0,1 dS/m.
14 © ISO 2009 – All rights reserved
8.3 Reagents
All reagents shall be of recognized analytical grade. Use water conforming to Class 2 of ISO 3696, i.e. having
an electrical conductivity no greater than 0,1 dS/m at 25 °C at the time of use.
8.3.1 Hydrogen peroxide solution, 30 % volume fraction.
NOTE A 30 % volume fraction solution is one which will yield 30 ml of gaseous oxygen from 100 ml of solution (under
standard conditions of temperature and pressure) upon reduction to water, either by chemical means or by boiling.
8.3.2 Solution of a dispersing agent.
The most widely used dispersing agent is that prepared by dissolving 33 g of sodium hexametaphosphate and
7 g of anhydrous sodium carbonate in water to make 1 L of solution. This is the preferred dispersant. Store
away from strong sunlight and preferably in a dark bottle. Record the date of preparation on the bottle. The
solution is unstable and shall be replaced after one month.
Buffered sodium hexametaphosphate is commonly referred to in the literature as “Calgon”. This is a trade
name. The substance sold as such is often not the reagent described in this subclause, is of variable
composition, and shall not be used as a dispersing agent in the method given in this International Standard
(Reference [8] in the Bibliography).
It is permissible to use other dispersing agents (see the last paragraph of this subclause), the choice of which
shall be recorded in the test report (Clause 10). Whichever dispersant proves to be the most suitable for a
particular soil, it is essential that the suspension be examined visually to ensure that effective dispersion has
occurred and that the dispersed suspension is stable, i.e. that no flocculation has occured or is occurring. This
inspection shall be carried out for each and every sample.
The sodium carbonate buffers the solution, and the suspension of the soil, to about pH 9,8. This dispersing
agent has been found successful with a very wide range of soils. However, if there are signs that dispersion is
ineffective, consider firstly that flocculating salts might be present (see 8.7). If dispersion is still unsuccessful
after removal of salts, then other dispersing agents should be considered. A very effective but less widely
used dispersing agent is prepared by replacing the sodium carbonate with 20 % volume fraction ammonia
solution, in the ratio of 5 ml ammonia solution to 150 ml of the hexametaphosphate solution. There are many
other dispersing agents (Reference [2] in the Bibliography). Whichever is chosen, considerable investigation
will be required to establish its effectiveness. It should be remembered that some soils show fewer problems
of dispersion if analysed without drying (see Annex A). Some soils derived from recent volcanic deposits will
disperse more effectively in an acid medium (Reference [9] in the Bibliography).
8.3.3 Octan-2-ol, or a similar volatile antifoaming agent.
NOTE Octan-2-ol is highly effective and relatively long-lasting. Ethanol or methanol can also be used, but the use of
pentan-2-ol (amyl alcohol) is discouraged because it is potentially addictive.
8.4 Calibrations
8.4.1 Sampling pipette (Figure 4)
Clean and dry the pipette thoroughly and immerse the tip in water held at the same temperature as that of the
constant-temperature environment (8.2.2). By means of a tube attached to C, draw water into the pipette
above E. Drain off the water above E through F. Drain the pipette into a weighing bottle of known mass and
determine the new mass. From the known masses, calculate the internal volume of the pipette. Repeat this
exercise three times and take the average of the three volumes as the internal volume of the pipette to the
nearest 0,05 ml (V ml).
c
8.4.2 Dispersing-agent correction
Follow this procedure each time a new batch of dispersing agent is prepared.
Pipette 25 ml of dispersing-agent solution into one of the glass sedimentation tubes, and fill the tube to the
500 ml mark with water. Mix the contents of the tube thoroughly. Place the tube in the constant-temperature
environment, and leave the tube for at least 1 h. Between any of the times at which samples may be taken
from the sampling tube (Table 3), take a sample (V ml) of the dispersing-agent solution from the
c
sedimentation tube using the sampling pipette. Drain the pipette into a weighing vessel of known mass, and
dry the contents of the vessel between 105 °C and 110 °C. Allow the vessel to cool in the desiccator and
determine the mass of the residue in the vessel to 0,000 1 g (m ).
r
The minimum temperature equilibration period in the water bath is 1 h, but if a large number of tubes is placed
in a bath, equilibration will take at least 4 h. In such cases, it is advantageous to arrange the work so that
equilibration takes place overnight. Equilibration will be quicker if the supply of water used to fill up the tubes is
kept at or near the same temperature as the constant-temperature environment.
8.5 Test sample
The test sample shall be taken from the material passing a 2 mm aperture sieve (see Clause 6 and 7.2) and
weighed to the nearest 0,001 g (m ). The mass of test sample depends on the type of soil. Approximately 30 g
s
for a sandy soil and 10 g for a clay soil are appropriate for pipette analysis, with proportionate masses for soils
intermediate to these extremes. For the hydrometer method (Annex B), take twice this amount of material.
Place the test sample in either the 650 ml glass beaker or the 300 ml centrifuge bottle (8.2.13 and its note).
Highly organic soils contain relatively little mineral matter. It might be necessary to take up to 100 g of such
soils in order to obtain sufficient mineral matter for a reliable analysis of the particle size distribution of this
component. Such a large amount of organic material should be apportioned between several vessels for ease
of operation, with combination of the mineral residues at a later stage.
8.6 Destruction of organic matter
Destroy the organic matter with hydrogen peroxide solution as follows. Add approximately 30 ml of water to
the test sample and allow it to become thoroughly wet (see Note 1 below). Add 30 ml of 30 % volume fraction
hydrogen peroxide solution and mix the contents of the vessel very gently using the glass or plastic rod. A
vigorous reaction can cause foaming of the sample mixture. This can be controlled by adding a few millilitres
of octan-2-ol. Allow any vigorous reaction to subside.
WARNING — Carry out this step with caution. Hydrogen peroxide can decompose violently with some
forms of organic matter, manganese compounds and finely-particulate iron sulfides, all of which can
occur in soil. Do not examine the reaction by looking into the top of the vessel. Do not accelerate an
apparently slow reaction by heating or addition of more hydrogen peroxide.
If using the 650 ml beaker, cover with the cover glass and leave overnight. Place the vessel on the hotplate or
Bunsen burner, as appropriate (8.2.20), and warm gently. Control any foaming with octan-2-ol as before, and
stir the contents frequently. Do not allow the contents to dry out, adding more water if necessary. Bring the
suspension to a gentle boil and heat until all signs of bubbling due to decomposition of hydrogen peroxide
have ceased. If there is still-undecomposed organic matter, remove the vessel from the heat, allow it to cool
and repeat the treatment with hydrogen peroxide. Highly organic soils will need several such treatments, the
products of the reaction being removed after every 2 or 3 treatments before continuing with more peroxide.
If destruction of organic matter has been carried out in a centrifuge bottle, bring the volume of the contents to
between 150 ml and 200 ml by addition of water. If a glass beaker has been used, then transfer the contents
to a centrifuge bottle, taking care to remove all traces of material from the sides of the beaker by means of the
rubber sleeve on the glass or plastic rod. Again, the final volume should be 150 ml to 200 ml. Centrifuge the
bottle so as to obtain a clear supernatant [15 min at a minimum relative centrifugal force (RCF) of 400g is
recommended], and decant the latter or remove by means of the suction device. Repeat the treatment until
the supernatant is colourless or nearly so.
16 © ISO 2009 – All rights reserved
NOTE 1 Dry organic materials are often strongly hydrophobic, in which case the addition of a few drops of octan-2-ol
can be beneficial.
If a centrifuge is not available, the mineral residues may be flocculated by adding 25 ml of 1 mol/l calcium
chloride solution. Stir thoroughly, bring to about 250 ml with water, allow to stand until the supernatant is clear,
then siphon or decant this from the residue. Add another 250 ml of water and repeat the washing procedure
until the dark residues of the decomposed organic matter have gone. Check that the electrical conductivity of
the washings is below 0,4 dS/m before attempting to disperse the
...
NORME ISO
INTERNATIONALE 11277
Deuxième édition
2009-09-15
Qualité du sol — Détermination de la
répartition granulométrique de la matière
minérale des sols — Méthode par
tamisage et sédimentation
Soil quality — Determination of particle size distribution in mineral soil
material — Method by sieving and sedimentation
Numéro de référence
©
ISO 2009
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Publié en Suisse
ii © ISO 2009 – Tous droits réservés
Sommaire Page
Avant-propos .iv
Introduction.v
1 Domaine d'application .1
2 Références normatives.1
3 Terminologie et symboles .2
4 Principe.3
5 Échantillonnage sur le terrain.4
6 Préparation des échantillons .4
7 Tamisage à sec (matériau > 2 mm) .4
8 Tamisage humide et sédimentation (matériau < 2 mm).7
9 Fidélité .21
10 Rapport d'essai.21
Annexe A (normative) Détermination de la répartition granulométrique de la fraction minérale des
sols non séchés avant analyse.22
Annexe B (normative) Détermination de la répartition granulométrique de la fraction minérale des
sols par la méthode du densimètre après destruction de la matière organique.25
Bibliographie.34
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée
aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec
la Commission électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI,
Partie 2.
La tâche principale des comités techniques est d'élaborer les Normes internationales. Les projets de Normes
internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur
publication comme Normes internationales requiert l'approbation de 75 % au moins des comités membres
votants.
L'attention est appelée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable de ne
pas avoir identifié de tels droits de propriété et averti de leur existence.
L'ISO 11277 a été élaborée par le comité technique ISO/TC 190, Qualité du sol.
Cette deuxième édition annule et remplace la première édition (ISO 11277:1998) dont elle constitue une
révision mineure et incorpore l'ISO 11277:1998/Cor.1:2002.
iv © ISO 2009 – Tous droits réservés
Introduction
Le comportement physique et chimique des sols est contrôlé en partie par les quantités de particules
minérales de différentes tailles qui s'y trouvent. L'objet de la présente Norme internationale est le mesurage
de ces quantités (exprimé en proportion ou en pourcentage de la masse totale du sol minéral), au sein de
classes de tailles indiquées.
La détermination de la répartition granulométrique est affectée par la matière organique, les sels solubles, les
agents de cémentation (particulièrement les oxydes de fer), les substances relativement insolubles comme les
carbonates et les sulfates, ou les combinaisons de ceux-ci. Le comportement de certains sols change dans
une telle proportion au séchage que la répartition granulométrique de la matière sèche a peu ou pas de
rapport avec celle de la matière que l'on trouve dans des conditions naturelles. Ceci est particulièrement vrai
pour les sols riches en matière organique, ceux élaborés à partir de dépôts volcaniques récents, certains sols
tropicaux altérés et les sols souvent décrits comme «à forte cohésion» (Référence [3] dans la Bibliographie).
D'autres sols, comme les sols nommés «sub-plastic» d'Australie, montrent peu ou pas de tendance à se
disperser dans le cadre de traitements normaux de laboratoire, en dépit d'une importante teneur en argile
mise en évidence sur le terrain.
Les modes opératoires indiqués dans la présente Norme internationale tiennent compte des différences entre
les sols provenant d'environnements différents, et la méthodologie présentée est conçue pour les traiter de
façon structurée. Ces différences de comportement du sol peuvent être très importantes, mais leur perception
dépend généralement de la connaissance locale. Étant donné que le laboratoire est souvent éloigné du site
de prélèvement sur le terrain, les informations fournies par l'équipe sur le terrain deviennent cruciales pour le
choix d'un mode opératoire approprié de laboratoire. Ce choix ne peut être fait que si le laboratoire est
pleinement informé de ces données de base.
NORME INTERNATIONALE ISO 11277:2009(F)
Qualité du sol — Détermination de la répartition
granulométrique de la matière minérale des sols — Méthode par
tamisage et sédimentation
AVERTISSEMENT — Tous les modes opératoires de la présente Norme internationale doivent être mis
en œuvre par du personnel compétent, formé et convenablement encadré. L'attention est attirée sur
certains phénomènes dangereux connus, mais il est néanmoins essentiel que les utilisateurs
respectent les consignes de sécurité dans leurs pratiques de travail et, qu'en cas de doute, ils
recherchent un avis compétent.
Il est également essentiel que les utilisateurs de la présente Norme internationale la lisent en entier
avant d'entamer une opération quelconque, tout défaut de lecture de certains points pouvant entraîner
des erreurs d'analyse et donc des dangers.
1 Domaine d'application
La présente Norme internationale spécifie une méthode de base de détermination de la répartition
granulométrique des matières minérales des sols, y compris la fraction minérale des sols organiques. Elle
propose également des modes opératoires permettant de traiter les sols particuliers cités dans l'introduction.
La présente Norme internationale a été élaborée pour être largement utilisée dans le domaine de la science
de l'environnement, et son utilisation dans des recherches géotechniques est un point pour lequel un avis
professionnel peut se révéler nécessaire.
Un objectif majeur de la présente Norme internationale est la détermination d'un nombre suffisant de fractions
granulométriques pour permettre la construction d'une courbe de répartition granulométrique fiable.
La présente Norme internationale ne s'applique pas à la détermination de la répartition granulométrique des
composants organiques du sol, à savoir les restes plus ou moins fragiles, partiellement décomposés, de
plantes ou d'animaux. Il est également à noter que les traitements chimiques préalables et les étapes de
manipulation mécanique dans la présente Norme internationale peuvent entraîner la désintégration de
particules à faible cohérence qui, du point de vue d'une inspection sur le terrain, pourraient être considérées
comme des particules primaires et mieux décrites en tant qu'agrégats. Si cette désintégration n'est pas
souhaitable, alors la présente Norme internationale n'est pas utilisée pour la détermination de la répartition
granulométrique de ces matières à faible cohérence.
2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent document. Pour les
références datées, seule l'édition citée s'applique. Pour les références non datées, la dernière édition du
document de référence s'applique (y compris les éventuels amendements).
ISO 565:1990, Tamis de contrôle — Tissus métalliques, tôles métalliques perforées et feuilles
électroformées — Dimensions nominales des ouvertures
ISO 3310-1:2000, Tamis de contrôle — Exigences techniques et vérifications — Partie 1: Tamis de contrôle
en tissus métalliques
ISO 3310-2:1999, Tamis de contrôle — Exigences techniques et vérifications — Partie 2: Tamis de contrôle
en tôles métalliques perforées
ISO 3696:1987, Eau pour laboratoire à usage analytique — Spécification et méthodes d'essai
ISO 11464:2006, Qualité du sol — Prétraitement des échantillons pour analyses physico-chimiques
3 Terminologie et symboles
3.1 Terminologie
Les particules appartenant à des gammes ou à des classes de tailles particulières sont généralement décrites
comme des galets, des graviers, du sable grossier, des limons, etc. La signification de ces appellations
consacrées par l'usage diffère selon les pays et dans certains cas il n'existe pas de traduction exacte de ces
mots d'une langue à l'autre; par exemple le mot néerlandais «zavel» n'a pas d'équivalent en anglais. La seule
fraction pour laquelle il semble y avoir un accord est l'argile qui est définie comme une matière de moins de
0,002 mm de diamètre sphérique équivalent (Références [1] et [3] dans la Bibliographie). Ces appellations
traditionnelles ne doivent pas être utilisées pour décrire les résultats de la détermination granulométrique
conformément à la présente Norme internationale. Des phrases comme «. traversant un tamis à ouverture
de 20 mm .» ou «. inférieur à un diamètre sphérique équivalent de 0,063 mm .» doivent être utilisées à la
place. Si les appellations traditionnelles doivent être utilisées, par exemple en référence croisée avec une
autre Norme internationale ou nationale, il convient que le nom populaire soit explicitement défini, de façon à
éliminer tout doute sur la signification voulue, par exemple limon (diamètre sphérique équivalent de 0,063 mm
à 0,002 mm) (voir l'Article 4). En outre, il est courant d'utiliser le mot «texture» pour décrire les résultats de
mesurage de répartition granulométrique, par exemple «la taille de particule de ce sol est une texture
argileuse». Ceci est incorrect car les deux concepts sont différents, et le mot «texture» ne doit pas être utilisé
dans le rapport d'essai (Article 10) pour décrire les résultats obtenus en utilisant la présente Norme
internationale.
Il est courant de dire que les tamis ont un numéro de vide de maille ou un numéro de maille particulier. Ces
termes ne sont pas équivalents au terme ouverture et les rapports entre les différents numéros ne sont pas
immédiatement évidents. Il est difficile de justifier l'utilisation des numéros de maille comme mesure de la
taille de particules et il ne faut donc pas les indiquer dans le rapport donnant les résultats de la présente
Norme internationale.
3.2 Symboles
Les symboles qui suivent sont utilisés dans le texte et, le cas échéant, sont accompagnés des unités et
grandeurs correspondantes (les conventions du système international SI sont respectées pour les unités
courantes, par exemple g = gramme; m = mètre; mm = millimètre; s = seconde, etc.).
Mg mégagramme (10 g);
mPa millipascal;
t est le temps, en secondes, de décantation d'une particule de diamètre d ;
p
η est la viscosité dynamique de l'eau à la température d'essai (voir Tableau B.2), en millipascals par
seconde;
h est la profondeur de prélèvement, en centimètres;
ρ est la masse volumique moyenne des particules, en mégagrammes par mètre cube (considérée égale
s
à 2,65 Mg/m ; voir note à l'Article 4);
r est la masse volumique du liquide contenant la suspension de sol, en mégagrammes par mètre cube
w
(considérée égale à 1,00 Mg/m ; voir note à l'Article 4);
g est l'accélération due à la pesanteur, en centimètres par seconde carrée (c'est-à-dire 981 cm/s );
d est le diamètre sphérique équivalent de la particule concernée, en millimètres.
p
2 © ISO 2009 – Tous droits réservés
4 Principe
La répartition granulométrique est déterminée par une combinaison de tamisage et de sédimentation à partir
d'un sol séché à l'air (Référence [3] dans la Bibliographie) (voir note ci-dessous). Une méthode pour un sol
non séché est donnée à l'Annexe A. Les particules ne traversant pas un tamis à ouverture de 2 mm sont
déterminées par tamisage à sec. Les particules traversant un tel tamis, mais retenues sur un tamis à
ouverture de 0,063 mm sont déterminées par une combinaison de tamisage par voie humide et par voie
sèche, alors que les particules traversant le dernier tamis sont déterminées par sédimentation. Le
prélèvement à la pipette constitue la méthode recommandée. Une méthode au densimètre est donnée à
l'Annexe B. La combinaison du tamisage et de la sédimentation permet l'élaboration d'une courbe de
répartition granulométrique continue.
Les points clés de ce mode opératoire sont résumés sous forme de diagramme à la Figure 2. La présente
Norme internationale exige que les proportions des fractions séparées par sédimentation et tamisage soient
déterminées à partir des masses obtenues par pesée. D'autres méthodes de détermination de la masse des
fractions reposent sur des principes tels que l'interaction des particules avec un rayonnement
électromagnétique ou des champs électriques (Référence [1] dans la Bibliographie). Il est souvent
extrêmement difficile de corréler les valeurs obtenues par ces différentes méthodes pour un même échantillon.
Un des buts visés par la présente Norme internationale est donc d'aider, par un respect strict des détails
indiqués, à minimiser la variation dans la détermination de la répartition granulométrique des sols minéraux
par différents laboratoires. Les proportions des différentes fractions ne doivent donc être déterminées que par
pesage. La conformité à la présente Norme internationale ne peut être revendiquée dans le rapport d'essai
(Article 10) si cette méthode n'est pas utilisée.
Les méthodes de la pipette et du densimètre supposent que la décantation des particules dans le cylindre de
sédimentation est conforme à la loi de Stokes (Références [1], [3] et [6] dans la Bibliographie) avec les
contraintes que cela implique, à savoir:
a) les particules sont des sphères lisses et rigides;
b) la décantation des particules s'effectue en écoulement laminaire, c'est-à-dire un écoulement dont le
nombre de Reynolds est inférieur à 0,2. Cette contrainte fixe un diamètre sphérique équivalent maximal
de particule (voir ci-dessous) légèrement supérieur à 0,06 mm pour que la décantation se fasse par
gravité selon la loi de Stokes (Référence [1] dans la Bibliographie);
c) la suspension des particules est suffisamment diluée pour garantir qu'aucune particule n'affecte la
décantation d'autres particules;
d) il n'y a pas d'interaction entre la particule et le fluide;
e) le diamètre de la colonne de suspension est grand par rapport au diamètre de la particule, c'est-à-dire
que le fluide est à «étendue infinie»;
f) la particule a atteint sa vitesse limite;
g) les particules ont la même densité.
Ainsi, le diamètre d'une particule est défini en termes de diamètre d'une sphère dont le comportement en
suspension correspond à celui de la particule. Cela correspond au concept de diamètre sphérique équivalent.
C'est le principe sur lequel se fonde, dans la présente Norme internationale, l'expression du diamètre des
particules dérivant de la sédimentation.
La loi de Stokes peut, pour les besoins de la présente Norme internationale, être écrite sous la forme:
⎡⎤
th=−18ηρ ρgd
()
sw p
⎣⎦
où
t est le temps, en secondes, de décantation d'une particule de diamètre d (voir ci-dessous);
p
η est la viscosité dynamique de l'eau à la température d'essai (voir Tableau B.2), en millipascals par
seconde;
h est la profondeur de prélèvement, en centimètres;
ρ est la masse volumique moyenne des particules, en mégagrammes par mètre cube (considérée
s
égale à 2,65 Mg/cm , voir note);
ρ est la masse volumique du liquide contenant la suspension de sol, en mégagrammes par mètre cube
w
(considérée égale à 1,00 Mg/cm , voir note);
g est l'accélération due à la pesanteur, en centimètres par seconde carrée (c'est-à-dire 981 cm/s );
d est le diamètre sphérique équivalent de la particule concernée, en millimètres.
p
NOTE Il est reconnu qu'il existe des différences considérables entre les masses volumiques des particules du sol,
mais dans le cadre de la présente Norme internationale, il est supposé que la masse volumique moyenne des particules
est celle du quartz, c'est-à-dire 2,65 Mg/m (Référence [7] dans la Bibliographie), car c'est le minéral le plus commun dans
3 3
une très large gamme de sols. La masse volumique de l'eau est de 0,998 2 Mg/m et de 0,995 6 Mg/m à 20 °C et 30 °C
respectivement (Référence [5] dans la Bibliographie). Étant donné l'effet de l'ajout d'une petite quantité de dispersant (voir
8.3.2), la masse volumique de l'eau est prise égale à 1,000 0 Mg/m pour la gamme de température autorisée de la
présente Norme internationale (8.2.2).
En outre, pour l'usage courant, il est recommandé que les temps d'échantillonnage soient convertis en
minutes et/ou heures, de manière appropriée, afin de réduire le risque d'erreur (voir Tableau 3).
5 Échantillonnage sur le terrain
La masse d'échantillon prélevée sur le terrain doit être représentative de la répartition granulométrique,
particulièrement si la quantité des particules les plus volumineuses doit être déterminée de façon fiable. Le
Tableau 1 donne les masses minimales recommandées.
6 Préparation des échantillons
Les échantillons doivent être préparés conformément aux méthodes données dans l'ISO 11464.
NOTE Pour de nombreuses applications, la répartition granulométrique n'est déterminée que pour la fraction de sol
traversant un tamis de 2 mm d'ouverture de mailles. Dans ce cas, l'échantillon pour essai (8.5) peut être prélevé
conformément aux modes opératoires de l'ISO 11464 ou bien à partir de la matière traversant un tamis de 2 mm
d'ouverture de mailles conformément à 7.2.
7 Tamisage à sec (matériau > 2 mm)
7.1 Généralités
Le mode opératoire spécifié dans le présent article s'applique à la matière retenue sur un tamis de 2 mm
d'ouverture de mailles. Le Tableau 2 donne la masse maximale qui doit être retenue sur des tamis de
différents diamètres et de différentes ouvertures. Si la quantité de matériau retenue est supérieure, elle doit
être subdivisée de façon appropriée et retamisée.
7.2 Appareillage
7.2.1 Tamis de contrôle, dont les ouvertures de mailles sont conformes à l'ISO 565, avec des couvercles
et des réceptacles appropriés.
4 © ISO 2009 – Tous droits réservés
Il convient d'utiliser toute la gamme des tamis correspondant à la taille maximale de particules présentes (voir
Tableau 1 et 7.2.3). Les ouvertures choisies doivent être indiquées dans le rapport d'essai (Article 10). La
précision des tamis doit être contrôlée mensuellement par rapport à un jeu de tamis étalons conservés à cet
effet et à l'aide d'une méthode reconnue, comme par exemple la comparaison avec des matériaux de
référence, l'analyse au microscope, etc. (Référence [1] dans la Bibliographie) en fonction de l'ouverture de
mailles du tamis. Les tolérances doivent respecter les exigences de l'ISO 3310-1 et de l'ISO 3310-2. Les
tamis ne respectant pas ces spécifications doivent être mis au rebut. Un enregistrement des résultats d'essai
doit être conservé.
Les tamis en laiton sont particulièrement sujets aux détériorations et aux déformations. Les tamis en acier
sont vivement recommandés pour les ouvertures importantes.
On doit s'assurer que les couvercles et réceptacles ne fuient pas. Les tamis doivent être inspectés chaque
semaine lorsqu'ils sont utilisés régulièrement, et à chaque utilisation s'ils sont sollicités moins souvent. Un
enregistrement de ces inspections doit être conservé. Les tamis à trous ronds ne doivent pas être utilisés.
7.2.2 Balance, précise à ± 0,5 g près.
7.2.3 Tamiseur mécanique.
Il est généralement peu pratique de tamiser mécaniquement à des ouvertures de tamis supérieures à 20 mm,
sauf si un équipement à haute capacité est disponible. Le tamiseur de tamis mécanique est essentiel pour
tamiser efficacement à des ouvertures plus petites.
7.2.4 Brosse pour tamis et brosse à poil dur.
7.3 Mode opératoire
Peser l'échantillon pour essai sec, préparé conformément à l'ISO 11464, à 0,5 g près (m ). Placer le matériau
pesé sur le tamis de 20 mm et, en brossant doucement la matière au-dessus des mailles du tamis avec la
brosse à poil dur (pour retirer le sol qui adhère), tamiser l'échantillon. Veiller à ne pas détacher de fragments
des particules primaires. Tamiser le refus sur une colonne de tamis d'ouvertures choisies (7.2.1), et
enregistrer la quantité retenue sur chaque tamis à 0,5 g près. Ne pas surcharger les tamis (voir Tableau 1),
mais tamiser par portions, si nécessaire.
Peser la matière traversant le tamis à ouverture de 20 mm (m ), ou une partie convenable de celle-ci (m )
2 3
(voir Tableau 2) obtenue par une méthode appropriée de sous-échantillonnage (voir Article 6), et la placer sur
une colonne de tamis dont le plus bas a une ouverture de 2 mm. Secouer les tamis avec un moyen
mécanique jusqu'à ce qu'aucune matière ne les traverse (voir note). Enregistrer la masse de matière retenue
sur chaque tamis et la masse traversant le tamis à ouverture de 2 mm.
Il convient que la masse totale des fractions soit égale, à moins de 1 % près, à m ou m , selon le cas. Si elle
2 3
ne l'est pas, vérifier si un tamis est endommagé et le changer si nécessaire (voir 7.2.1).
Il convient de vérifier la performance de l'équipement tous les mois par rapport à un échantillon de contrôle
approprié, par exemple un échantillon de matériau avec particules de référence, des perles de verre. Les
résultats de cette vérification doivent être enregistrés.
NOTE Pour des raisons pratiques, il est courant de choisir une durée normalisée de tamisage qui donne un niveau
acceptable d'efficacité pour une large gamme d'échantillons. La durée minimale recommandée est de 10 min.
Tableau 1 — Masse d'échantillon de sol à prélever pour le tamisage
Dimension maximale des particules Masse minimale d'échantillon à
constituant plus de 10 % du sol prélever pour le tamisage
(donnée comme ouverture du tamis de
kg
contrôle, en mm)
63 50
50 35
37,5 15
28 6
20 2
14 1
10 0,5
6,3 0,5
5 0,2
2 ou plus petit 0,1
Tableau 2 — Masse maximale de matière pouvant être retenue sur chaque tamis de contrôle
à la fin du tamisage
Masse maximale
kg
Dimension de l'ouverture
du tamis de contrôle
Diamètre du tamis
mm
mm 450 300 200
50 10 4,5
37,5 8 3,5
28 6 2,5
20 4 2,0
14 3 1,5
10 2 1,0
6,3 1,5 0,75
5 1,0 0,5
3,35 0,3
2 0,2
1,18 0,1
0,6 0,075
0,425 0,075
0,3 0,05
0,212 0,05
0,15 0,04
0,063 0,025
6 © ISO 2009 – Tous droits réservés
7.4 Calcul et expression des résultats
Pour les matériaux retenus par le tamis de 20 mm et les tamis de plus grande ouverture, calculer la proportion
en masse retenue par chaque tamis par rapport à m . Par exemple:
Proportion retenue sur le tamis de 20 mm = [m(20 mm)]/m
Pour les matériaux traversant le tamis de 20 mm, multiplier la masse de la matière traversant chaque tamis
par m /m et calculer la proportion par rapport à m . Par exemple:
2 3
Proportion retenue sur le tamis de 6,3 mm = m(6,3 mm) [(m /m )/m ]
2 3 1
Présenter les résultats dans un tableau montrant, à deux chiffres significatifs, la proportion en masse retenue
sur chaque tamis, et la proportion traversant le tamis de 2 mm. Utiliser également ces données pour élaborer
une courbe de distribution cumulative (voir Figure 1).
8 Tamisage humide et sédimentation (matériau < 2 mm)
8.1 Généralités
Le présent article spécifie le mode opératoire (voir Figure 2) pour la détermination de la répartition
granulométrique de la matière traversant le tamis à ouverture de 2 mm jusqu'à un diamètre sphérique
équivalent < 0,002 mm (voir note). Afin de garantir que les particules primaires sont mesurées plutôt que des
agrégats faiblement adhérents, la matière organique et les sels sont éliminés, particulièrement les sels peu
solubles comme le gypse, qui empêcheraient la dispersion et/ou entraîneraient la floculation des particules
plus fines en suspension (voir 8.6). Un agent dispersant est ajouté (8.8). Ces opérations sont exigées dans la
présente Norme internationale et leur omission doit invalider l'application de celle-ci. Parfois, des oxydes de
fer et des carbonates, en particulier de calcium et/ou de magnésium, sont également éliminés. Les modes
opératoires recommandés pour l'élimination de ces composés sont indiqués à la note en 8.7. L'élimination de
tout composé doit être enregistrée dans le rapport d'essai (Article 10).
NOTE La sédimentation par gravité peut donner une valeur pour la quantité totale de matériaux ayant un diamètre
sphérique équivalent < 0,002 mm. Cependant, la méthode ne peut être utilisée pour diviser davantage cette classe avec
fiabilité, car des particules ayant un diamètre sphérique équivalent inférieur à environ 0,001 mm peuvent rester en
suspension presque indéfiniment à cause du mouvement brownien (Référence [1] dans la Bibliographie).
8.2 Appareillage
L'appareillage spécifié ci-après est prévu pour traiter un seul échantillon. En fait, il est plus rentable de
travailler avec des lots d'échantillons. L'expérience a montré (Référence [6] dans la Bibliographie) qu'un
opérateur peut traiter simultanément jusqu'à 36 échantillons par lot, avec un appareillage et un espace
suffisants, en particulier si les calculs sont effectués par ordinateur.
8.2.1 Pipette de prélèvement, d'un modèle similaire à celui représenté à la Figure 3, la principale exigence
étant que la plus petite zone possible de suspension doit être prélevée. La pipette ne doit pas avoir un volume
inférieur à 10 ml et doit être tenue par un châssis afin de pouvoir être abaissée à une profondeur déterminée
à l'intérieur du tube de sédimentation (voir Figure 4).
NOTE L'expérience montre qu'un volume maximal de 50 ml est plus que suffisant pour la plupart des objectifs. Une
pipette de 25 ml est un compromis convenable pour une analyse de routine mais une pipette de plus petit volume est
suffisante pour des sols dont environ 10 % en fraction massique ont un diamètre sphérique équivalent < 0,063 mm.
Au-dessous de cette quantité, une précision supérieure peut être obtenue avec une pipette de plus grand volume.
Figure 1 — Diagramme de répartition granulométrique
8 © ISO 2009 – Tous droits réservés
Figure 2 — Diagramme du mode opératoire
Dimensions en millimètres
Légende
1 capacité de l'entonnoir cylindrique: environ 125 ml
2 capacité de la pipette et du robinet: environ 10 ml
NOTE Ce montage donne de bons résultats mais d'autres conceptions peuvent également être utilisées.
Figure 3 — Pipette de prélèvement pour essai de sédimentation
10 © ISO 2009 – Tous droits réservés
Légende
A et B entonnoir cylindrique de 125 ml avec robinet
d'arrêt
C tube d'aspiration de sûreté
D ampoule d'aspiration
E robinet
F tube de sortie
G pipette de prélèvement
H tube de sédimentation
1 échelle graduée en millimètres
2 colliers
3 panneau coulissant
4 bain thermostaté
NOTE Ce montage donne de bons résultats mais d'autres conceptions peuvent également être utilisées.
a
D, F et G sont reliés au robinet E à 3 voies.
Figure 4 — Disposition pour une pipette de prélèvement s'abaissant dans la suspension de sol
8.2.2 Pièce à température constante ou bain thermostaté, dans lesquels la température peut être
maintenue constante entre 20 °C et 30 °C ± 0,5 °C. Si un bain est utilisé, il doit accepter un tube de
sédimentation immergé jusqu'au trait de jauge de 500 ml et ne doit pas faire vibrer le contenu du tube. De
même, si une salle est utilisée, elle et son mobilier doivent être construits de façon à éviter la vibration des
tubes et de leur contenu.
NOTE Cet intervalle de température a été choisi pour tenir compte des difficultés à maintenir une température
spécifiée dans différentes parties du monde. En outre, la température inférieure donne des durées de sédimentation qui
s'adaptent bien à une journée de travail moyenne, alors que la température supérieure permet encore une durée de
sédimentation correcte pour la fraction de diamètre sphérique équivalent de 0,063 mm (voir Article 4 et Tableau 3).
Tableau 3 — Temps de prélèvement à la pipette et diamètres sphériques équivalents, d ,
p
(pour une masse volumique de particule de 2,65 Mg/m ) pour une profondeur de prélèvement
de 100 mm ± 1 mm et à des températures différentes
Temps de démarrage de l'opération de prélèvement, après mélange
Température
a
er ème ème ème
1 prélèvement 2 prélèvement 3 prélèvement 4 prélèvement
°C
min s min s min s h min s
20 0 56 4 38 51 35 7 44 16
21 0 54 4 32 50 27 7 34 4
22 0 53 4 26 49 19 7 23 53
23 0 52 4 19 48 8 7 13 13
24 0 51 4 13 47 0 7 3 2
25 0 49 4 7 45 52 6 52 50
26 0 48 4 2 44 53 6 44 2
27 0 47 3 57 43 58 6 35 42
28 0 46 3 52 42 59 6 26 53
29 0 45 3 47 42 3 6 18 33
30 0 44 3 41 41 5 6 9 45
d (mm) 0,063 0,020 0,006 0,002
p
a
Profondeur de prélèvement portée à 200 mm ± 1 mm pour disposer d'un temps suffisant de stabilisation de la suspension après
mélange.
8.2.3 Deux tubes de sédimentation en verre, sans bec verseur, d'un diamètre intérieur d'environ 50 mm,
et d'une longueur totale de 350 mm, gradués à un volume de 500 ml, avec des bouchons de caoutchouc
adaptés, ou bien (si l'on prévoit une agitation par retournement) un système de mise en suspension.
8.2.4 Système de mise en suspension, constitué d'un matériau résistant à la corrosion, tel que présenté à
la Figure 5.
8.2.5 Cinq cristallisoirs de pesée en verre, de masse connue à 0,000 1 g près.
8.2.6 Agitateur mécanique, pouvant maintenir 30 g de sol en suspension dans 150 ml de liquide. Un
agitateur rotatif par retournement de 30 r/min à 60 r/min convient. L'agitateur énergique en va-et-vient et
l'agitateur rotatif dans le plan horizontal ne conviennent pas et ne doivent pas être utilisés (voir note en 8.9).
8.2.7 Tamis de contrôle, conformes à l'ISO 565, l'ISO 3310-1 et l'ISO 3310-2, ayant des ouvertures de
mailles de 2 mm et de 0,063 mm, plus deux tamis intermédiaires. Le rapport d'essai doit indiquer les
ouvertures utilisées. Les tamis à trous ronds ne doivent pas être utilisés.
NOTE Le choix du tamis à ouverture de 0,063 mm donné ici sert d'illustration mais correspond à l'usage courant qui
veut que cette taille de particule définisse la limite supérieure de la fraction limon. Les exigences locales peuvent spécifier
d'autres ouvertures. Le choix des ouvertures des tamis intermédiaires est une question de connaissances locales mais
l'expérience suggère que des tamis avec des ouvertures de mailles voisines de 0,2 mm et 0,1 mm sont utiles pour une
très grande variété de sols.
12 © ISO 2009 – Tous droits réservés
Dimensions en millimètres
Préparer un système tel qu'illustré; des matériaux convenables sont, entre autres:
a) laiton ou aluminium,
b) poly(méthacrylate de méthyle), ou
c) section de bouchon en caoutchouc emmanché sur une tige en verre, etc.
Figure 5 — Exemple de système de mise en suspension:
bouclier perforé monté sur une tige en verre
8.2.8 Diviseur d'échantillons approprié (Article 6).
8.2.9 Balance, pouvant peser avec une précision de ± 0,000 1 g près.
8.2.10 Étuve, pouvant maintenir une température comprise entre 105 °C et 110 °C.
8.2.11 Minuterie, pouvant être lue à 1 s près.
8.2.12 Dessiccateur, contenant du gel de silice anhydre (de préférence indiquant son degré d'humidité),
pouvant contenir les cinq cristallisoirs de pesée. Le déshydratant doit être inspecté chaque jour et séché entre
105 °C et 110 °C lorsqu'il n'est plus efficace.
8.2.13 Bécher en verre de forme haute, de 650 ml avec verre de montre adapté à l'ouverture, ou flacon à
centrifuger de 300 ml muni d'un couvercle étanche.
NOTE Cet appareillage est utilisé pour le traitement chimique préalable. Au cours de celui-ci, un problème constant
est l'adhérence de très fines particules au verre. Le problème est très réduit si le traitement est effectué dans un flacon à
centrifuger en polycarbonate ou en polysulfone. Ces deux matériaux supportent un chauffage répété à 120 °C et résistent
au peroxyde d'hydrogène et aux agents dispersants communs. Leur utilisation peut également faire gagner beaucoup de
temps à l'opérateur.
8.2.14 Centrifugeuse, pouvant contenir les flacons centrifuges de 300 ml (voir 8.8).
8.2.15 Éprouvette graduée de 100 ml.
8.2.16 Pipette de 25 ml.
8.2.17 Entonnoir de filtration en verre, pouvant contenir le tamis de 0,063 mm.
8.2.18 Pissette contenant de l'eau (voir 8.3).
8.2.19 Tige, de verre ou de plastique rigide, de 150 mm à 200 mm de longueur et de diamètre d'au moins
4 mm, avec un manchon de caoutchouc à une extrémité.
8.2.20 Plaque chauffante électrique, pouvant maintenir une température comprise entre 105 °C et 110 °C.
NOTE Une plaque chauffante est nécessaire si des flacons à centrifuger en polymère sont utilisés pour le traitement
chimique préalable, mais un bec Bunsen, une toile métallique et un trépied sont suffisants si l'on utilise des béchers en
verre.
8.2.21 Dispositif d'aspiration, similaire à celui présenté à la Figure 6, est utile mais non essentiel.
Légende
1 tube souple
2 pipette Pasteur ou similaire
3 réservoir (5 l ou 10 l)
a
Vers le vide.
Figure 6 — Schéma d'un dispositif d'aspiration
8.2.22 Pinceau pour tamis.
8.2.23 Conductimètre, précis à 0,1 dS/m.
14 © ISO 2009 – Tous droits réservés
8.3 Réactifs
Tous les réactifs doivent être de qualité analytique reconnue. Utiliser une eau conforme à la qualité 2
conformément à l'ISO 3696, c'est-à-dire dont la conductivité électrique ne dépasse pas 0,1 dS/m à 25 °C au
moment de l'utilisation.
8.3.1 Solution de peroxyde d'hydrogène, à 30 % (fraction volumique).
NOTE Une solution à 30 % (fraction volumique) est une solution qui dégage 30 ml d'oxygène à partir de 100 ml de
solution (dans des conditions normales de température et de pression) au moment de la réduction en eau par des moyens
chimiques ou par ébullition.
8.3.2 Solution de dispersant.
La plus répandue est celle préparée par dissolution de 33 g d'hexamétaphosphate de sodium et de 7 g de
carbonate de sodium anhydre dans de l'eau pour faire 1 l de solution. Ceci est le dispersant recommandé. Le
conserver à l'abri de la lumière et de préférence dans un flacon coloré. Enregistrer la date de préparation sur
le flacon. La solution est instable et doit être remplacée au bout d'un mois.
Dans la documentation, l'hexamétaphosphate de sodium tamponné est généralement nommé «Calgon». Il
s'agit d'un nom commercial. La substance vendue sous ce nom commercial n'est généralement pas le réactif
décrit dans le présent paragraphe, mais d'une composition variable et ne doit pas être utilisée comme agent
dispersant dans la méthode donnée dans la présente Norme internationale (Référence [8] dans la
Bibliographie).
Il est possible d'utiliser d'autres agents dispersants (voir le dernier alinéa du présent paragraphe), dont le
choix doit être enregistré dans le rapport d'essai (Article 10). Quel que soit le dispersant qui s'avère le mieux
adapté à un sol particulier, il est essentiel que la suspension soit examinée visuellement pour garantir qu'une
dispersion effective s'est produite et que la suspension dispersée est stable, c'est-à-dire qu'aucune floculation
ne s'est produite ou ne se produit. Cette inspection doit être effectuée pour chaque échantillon.
Le carbonate de sodium tamponne la solution, et la suspension de sol, à environ pH 9,8. Cet agent dispersant
s'est avéré efficace avec une très large gamme de sols. Cependant, si des signes indiquent que la dispersion
n'est pas effective, envisager d'abord que des sels provoquant une floculation peuvent être présents (voir 8.7).
Si la dispersion ne se produit toujours pas après l'élimination des sels, il convient de prendre en considération
d'autres agents dispersants. Un agent dispersant très efficace, mais moins largement utilisé, est préparé en
remplaçant le carbonate de sodium par une solution ammoniacale à 20 % en fraction volumique, avec un
rapport de 5 ml de solution ammoniacale pour 150 ml de solution d'hexamétaphosphate. Il existe de
nombreux autres agents dispersants (Référence [2] dans la Bibliographie). Quel que soit celui qui est choisi,
une recherche considérable est exigée pour établir son efficacité. Il convient de se souvenir que certains sols
posent moins de problèmes de dispersion s'ils sont analysés sans séchage (voir Annexe A). Certains sols
dérivés de dépôts volcaniques récents se dispersent plus efficacement dans un milieu acide (Référence [9]
dans la Bibliographie).
8.3.3 Octane-2-ol, ou un agent antimousse volatil similaire.
NOTE L'octane-2-ol est très efficace et son effet est de durée relativement longue. L'éthanol ou le méthanol peuvent
également être utilisés, mais l'utilisation de pentane-2-ol (alcool isoamylique) est déconseillée parce qu'il peut créer une
accoutumance physiologique.
8.4 Étalonnages
8.4.1 Pipette de prélèvement (voir Figure 4)
Nettoyer et sécher soigneusement la pipette et immerger la pointe dans de l'eau maintenue à la même
température que l'enceinte thermostatée (8.2.2). Avec un tube fixé sur C, aspirer l'eau dans la pipette
au-dessus de E. Vider l'eau au-dessus de E jusqu'à F. Vider la pipette dans un flacon de pesage
préalablement taré et déterminer la nouvelle masse. À partir des masses connues, calculer le volume interne
de la pipette. Répéter cette opération trois fois et prendre la moyenne des trois volumes comme volume
interne de la pipette, à 0,05 ml près (V ml).
c
8.4.2 Correction de la masse de dispersant
Suivre ce mode opératoire à chaque fois qu'une nouvelle solution de dispersant est préparée.
Ajouter à la pipette 25 ml de solution de dispersant dans un des tubes de sédimentation en verre, et remplir le
tube jusqu'au trait de jauge de 500 ml avec de l'eau. Mélanger soigneusement le contenu du tube. Placer le
tube dans l'enceinte thermostatée pendant au moins 1 h. Choisir un temps de prélèvement (voir Tableau 3),
prélever un échantillon (V ml) de la solution d'agent dispersant dans le tube de sédimentation en utilisant la
c
pipette de prélèvement. Vider la pipette dans un cristallisoir de pesage taré, et sécher le contenu du récipient
entre 105 °C et 110 °C. Laisser refroidir le récipient dans un dessiccateur et déterminer la masse du résidu à
0,000 1 g près (m ).
r
La durée minimale de mise à température dans le bain-marie est de 1 h, mais si un plus grand nombre de
tubes est placé dans un bain, la mise à l'équilibre prend au moins 4 h. Dans ce cas, il est avantageux
d'organiser le travail de façon que la mise à température ait lieu la nuit. Elle sera plus rapide si l'eau utilisée
pour remplir les tubes est à la même ou quasi la même température que l'enceinte thermostatée.
8.5 Échantillon pour essai
L'échantillon pour essai doit être prélevé sur la fraction de matériau inférieure à 2 mm (voir Article 6 et 7.2) et
pesé à 0,001 g près (m ). La masse de l'échantillon pour essai dépend du type de sol. Environ 30 g pour un
s
sol sableux et 10 g pour un sol argileux conviennent pour une analyse par pipette, avec des proportions
adaptées pour les sols se situant entre ces extrêmes. Pour la méthode du densimètre (Annexe B), prendre
deux fois cette quantité. Placer l'échantillon pour essai dans le bécher en verre de 650 ml ou le flacon à
centrifuger de 300 ml (8.2.13 et sa note).
Les sols très organiques contiennent relativement peu de matière min
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