ASTM C1079-87(1992)e1

Test Methods for Determining the Water Content of Freshly Mixed Concrete (Withdrawn 1998)

General Information

• Status: Withdrawn
• Withdrawal Date: 09-Aug-1998
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.60 - Testing Fresh Concrete

Standards Content (Sample)

ASTM C3079*EL ô7 H 0759530 0504402 9 H
AMERICAN SOCIETY K)R TESTING AND MATERIALS
([lb Designation: c 1079 - 87 (Reapproved 1992)e1
1916 RaceSt Philadelphia, Pa 19103
Reprinted from the Annual Bwk of ASTM Standards. Copyrbht ASTM
If not listed In the current combined indew, will appear in the next &ibn.
Standard Test Methods for
Determining the Water Content of Freshly Mixed
Concrete‘
This standard is issued under the fixed designation C 1079; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
a NOTE-Editorial corrections were made in March 1992.
1. Scope concentration of the intermixed blank solution by volu-
metric titration or coulometric reference technique. rn Pro-
1.1 These test methods cover two chemical procedures for
cedure A, the chloride ion concentration is determined by
determining the free-water content of a sample of freshly
adding an excess of a standard silver nitrate solution to a
mixed concrete. These test methods are applicable to either
fixed volume of each intermixed solution. Chloride ions are
laboratory or field conditions. The choice of which proce-
thereby precipitated as silver chloride. The residual silver is
dure to use is at the discretion of the user, The environment
determined by titrating with a standard thiocyanate solution
in which these test methods are used may have some bearing
in the presence of a ferric alum end point indicator. In
on the choice.
Procedure B, the chloride ion concentration is determined by
1.2 The values stated in inch-pound units are to be
adding a fixed volume of the intermixed solution to the acid
regarded as the standard except in regard to sieve sizes which
buffer. The chloride ion concentration is then determined
are in accordance with Specification E 11.
using an instrumental coulometric reference technique. (If
1.3 This standard does not purport to address all of the
the blank test indicates no chlorides are present in the
safety problems, if any, associated with its use. It is the
concrete, the blank fest may be waived in subsequent
responsibility of the user of this standard to establish appro-
testing.)
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. See Note 1 €or a
4. Significance and Use
specific warning statement.
4. I The test results can be used to determine variability of
water content in a batch of concrete and the Variability of
2. Referenced Documents
water content between different batches of nominally iden-
2.1 ASTM Standards:
tical concrete. If these test methods are used to indicate
C 94 Specification for Ready-Mixed Concrete2
concrete uniformity, correct and appropriate sampling pro-
C 127 Test Method for Specific Gravity and Absorption of
cedures must be followed. Sampling procedures are refer-
Coarse Asgregatez
enced in Section 6 of these test methods.
C 138 Test Method for Unit Weight, Yield, and Air
4.2 The water-cement ratio of a concrete sample can be
Content (Gravimetric) of Concrete2
estimated if these test methods are used in conjunction with
C 172 Practice for Sampling Fresh Concrete2
Test Methods C 1078.
C670 Practice for Preparing Precision and Bias State-
ments for Test Methods for Construction Materials2
5. Purity of Reagents
C 1078 Test Methods for Determining the Cement Con-
5.1 Purity of Reagents-Reagent grade chemicals shall be
tent of Freshly Mixed Concrete2
used in all tests. Unless otherwise indicated, it is intended
that all reagents shall conform to the specifications of the
3. Summary of Test Methods
Committee on Analytical Reagents of the American Chem-
3.1 A given mass of freshly mixed concrete is intermixed ical Society, where such specifications are a~ailable.~ Other
with a chloride solution of a given strength and volume. The grades may be used, provided it is first ascertained that the
chloride ion concentration of the intermixed solution is reagent is of sufficiently high purity to permit its use without
directly related to the water content of the concrete sample, lessening the accuracy of the determination. A comparison
and is determined by volumetric titration or coulometric of results obtained using the proposed grades with results
reference technique. A blank test is required. The blank test obtained using reagent grade chemicals shail be made to
intermixes a given volume of distilled water with a concrete ensure that the proposed grades are sufficiently pure, unless
sample of given mass and determines the chloride ion previous records confirm they are satisfactory.
These test methods are under the jurisdiction of ASTM Commitfee C-9 on 3 “Reagent Chemicals, American Chemical Society Specifications,” Am. Chem-
Concrete and Concrete Aggregates and are the direct responsibility of Subcom- ical Soc., Washington, DC. For suggestions on the testing of reagents not listed by
mittee C09.03.03 on Methods of Testing Fresh Concrete. the American Chemical Society, see “Reagent Chemicals and Standards,” by
Current edition approved May 29, 1987. Published July 1987. Joseph Rosin, D. Van Nostrand Co., ïnc., New York, NY, and the “United States
Annual Book o$ASTM Standards, Vol 04.02. Pharmacopeia.”
ASTM CL07î*El 87 W 0759CLO 0504403 O
4m C1079
5.2 Purity of Water-Unless otherwise indicated, ali refer- narrow-mouth conical beaker or Erlenmeyer flask.
ences to water shall be understood to mean distilled water or 7.1.7 Pipet, 25-mL volumetric glass, class A or B.
water of equal purity. 7.1.8 Automatic Pipets, 25 and 10 mL glass with poly-
tetrafluoroethylene (PTFE) plug. Two 25-mL automatic
6. Sampling
pipets are required. Alternatively, any volumetric dispenser
that has an accuracy equal to or greater than ~k0.05 mL and
6.1 The sample of concrete from which the water-content
a reproducibility equal to or greater than k0.02 mL may be
test specimens are made shall be representative of the entire
used.
batch and have a mass of not less than 20 kg. It shall be
7.1.9 Amber Reagent Bottles, two narrow-mouth, Boston,
obtained in accordance with Specification C 94 or Practice
round, amber, polypropylene, 32-oz. or 0.95 to 1-L reagent
C 172. Specification C 94 outlines procedures for sampling
bottles. They shall be equipped with two No. 6 rubber
for uniformity of concrete produced in truck mixers. If wet
stoppers, one with two holes, and one with three. They shall
sieving of aggregates larger than 1 Y2 inch is not permitted, the
also be equipped with dass tubing, siphon lines, 7-mm
wide-mouth jar in 7.1.4 should be large enough to accommo-
outside diameter (standard waii required); two for the three
date larger aggregate concrete.
hole stopper and one for the two hole stopper. There shall be
PROCEDURE A-BY VOLUMETRIC TITRATION METHOD
10 ft (3.0 m) of %-in. (6.4-mm) inside diameter amber
rubber-latex tubing required to connect the glass siphon lines
7. Apparatus
to the 25-mL automatic pipets.
7.1 The following comprise a recommended minimum 7.1.10 Buret, 100-mL acrylic body, Class A or B accuracy
selection of apparatus for use in conducting the required with a PTFE plug.
analysis, Apparatus other than that described in this section I. 1 1 Volumetric Flask, two 500-mL polyethylene
7.
can be used, provided they serve the same function. An volumetric flasks.
acceptable selection of apparatus is shown in Fig. 1.
7.1.12 Fixed- Volume Dispensers, polyethylene with
7.1,1 Balance, having a minimum capacity of 2600 g and polypropylene measuring chambers. One 2-mL and two
sensitivity of at least O. 1 g. 5-mL dispensers are required.
7.1,2 Shovel, Hand Scoops, and Rubber Gloves as re- 7.1.13 Carboys, rectangular, aspirator-type 2-gal (7.6-L)
quired. linear polyethylene carboys.
7.1.3 Sample Tub, 5-qt (4.7-L) polyethylene. 7.1.14 Clamps-One double-buret holder and one utiiity
7.1.4 Wide-Mouth Jar, Y2-gal (I .9-L) polyethylene, with clamp, having a three-pronged grip and vinylized jaws.
screw closure and lid.
8. Reagents
7.1.5 Universal Mixer-An end-over-end mixer, driven at
40 to 60 r/min capable of holding and turning end-over-end 8.1 Nitric Acid Solution (1 i- l)-Carefuliy add one
a %-gal (1 -9-L) wide-mouth jar containing 2.5 kg of material. volume of concentrated nitric acid ("O,, sp gr 1.42) to one
It shall be equipped with a O to 15 min timer and switch.
volume of water.
7.1.6 Conical Beaker or Erlenmeyer Flask-A 500-mL
8.2 Ferric Alum indicator Solution-Dissolve 50 g of
ferric ammonium sulphate [FeNH,(SO,), 1 2H20] in 1 O0
mL of water and add 5 drops of nitric acid solution (1 + 1).
8.3 Nitrobenzene (C6H,NOz) (sp gr 1.20)
NOTE 1: Warning-Nitrobenzene is extremely toxic and is rapidly
through the skin. Contact with the skin or clothing and
absorbed
inhalation of fumes and vapors shali be avoided. Due precaution shall be
observed when using the material.
8.4 Potassium Thiocyanate Solution (0.05 N)-Dissolve
24.3 f 0.2 g of dry potassium thiocyanate (KSCN) in water
and dilute to 5 L.
8.5 Silver Nitrate Solution (0.5 N)-Dissolve 255 f 2 g of
dry silver nitrate (AgNO,) in water and dilute to 3 L.
8.6 Sodium Chloride Solution (0.5 N)-Dissolve 292 f 3
a. Balance
g of dry sodium chloride (NaCl) in tap water and dilute to
b. Handscoop
10 L.
c. Sample tub
d. Wide-mouth jar
NOTE 2-Dry NaCl crystals dissolve slowly, and mechanical agita-
e. Universal mixer
tion is recommended to ensure that the crystals completely dissolve.
f. Conical beaker
g. Pipet, 25 mL
9. Calibration
h. Automatic pipet, 25 mL
i, Amber reagent bottles, rubber stoppers, and glass tubing
9.1 Blank Equivalent Constant-Using an automatic
i. Automatic pipet, 10 mL
pipet, place 10 mL of 0.5N AgN03 solution into a beaker.
k. Buret, 100 mL
Using futed-volume dispensers, add 10 mL of 1 + 1 "O,, 5
I. Volumetric flask, 500 rnL .
m. Fixed-volume dispensers
mL of ferric alum indicator solution, and 2 mL of
n. Carboys
nitrobenzene to the beaker. Swirl the contents of the beaker
well for a few seconds. Titrate the solution using a 100-mL
FIG. 1 Equipment Required for Determining the Water Content of
buret of 0.05N KSCN solution. Swirl the contents of the
Freshly Mixed Concrete Using Procedure A
ASTM CL079*EL 87 = 0759510 0504404 2
dm C 1079
_-
beaker during titration. Stop the titration when the first the blank. Using fixed-volume dispensers, add 10 mL of 1 +
1 "O,, 5 mL of ferric alum indicator solution, and 2 mL of
permanent reddish-brown color appears. Record the volume
nitrobenzene to each beaker. Swirl well.
of KSCN required to reach the end point. This volume is the
10.5 The chloride strength of the sample and blank
blank equivalent constant.
solutions in the beakers are determined by titration using the
9.2 Water Content versus Potassium Thiocyanate End
0.05N KSCN solution (in a 100-mL buret). The titration is
Point-Weigh out 100.0 f O. 1 g (100 mL) of water. Place the
: water in a clean, wide-mouth jar. Using a volumetric flask, speeded by initialiy adding 25 mL of 0.05N KSCN with an
500 mL of 0.5N NaCl solution. Secure the lid and mix in automatic pipet and then completing the titration with
add
a universal mixer for 3 min. Remove the jar from the mixer. KSCN from the 100-mL buret. Swirl the contents of the
Withdraw a 25-mL sample of the intermixed solution using a sample and blank beakers during titration. Stop the titrations
volumetric pipet. Place the 25-mL sample in a conical when the first permanent reddish-brown color appears,
beaker. Using an automatic pipet, add 25 mL of 0.5N Record the volumes of KSCN solution required to reach the
AgNO, to the beaker and, using fmed-volume dispensers, sample and the blank end points. If the concrete being tested
add 10 mL of 1 + 1 "O3, 5 mL of ferric alum indicator does not contain chlorides, use of the blank may be
solution, and 2 mL of nitrobenzene. Swirl well. Titrate using discontinued after the initial determination.
the 100-mL buret of 0.05N KSCN solution. Swirl the
contents of the beaker during titration. Titrate to a perma-
11. Calculation
nent reddish-brown color end point, Record the volume of
11.1 Calculate the KSCN equivalent, y, of the blanks in
KSCN. This is the KSCN volume required for a chloride-free
mL as follows:
concrete specimen containing 100 g of water.
y=a-x
9.3 Water Content versus Total Potassium Thiocyanate
Calibration Curve-Repeat the procedure in 9.2 for 140.0 f
where:
O. 1 g and 180.0 zk O. 1 g of water. Plot the water content in
a = the blank equivalent constant in accordance with 9.1,
grams versus KSCN in millilitres. Draw a smooth curve
mL, and
through the calibration data.
x = the volume of KSCN required to reach the end point
9.4 Calibration Requirements-The calibration proce-
of the blank in accordance with 10.5, mL.
dures in 9.1 through 9.3 are required each time new reagents
1 1.2 The water content is determined by using the calibra-
are used. A single-point calibration check in accordance with
tion curve described in 9.3. The KSCN value used with the
9.2 is required on a weekly basis before testing concrete
calibration curve is the sum of the volume of the potassium
specimens. If the single-point calibration check differs from
thiocyanate solution required for the sample (as determined
the established value by more than zk0.50 mL of KSCN, a
in 10.5) and the potassium thiocyanate equivalent of the
complete recalibration is required.
blank (y), The computed water content is in grams. (KSCN
value to use with curve)
10. Procedure
11.2.1 The computed water content is often stated as a
10.1 To obtain the test specimen, weigh out two test
percent of the total specimen weight by dividing the com-
specimens of 2000 k 200 g each from the sample obtained in puted water content, w, by the recorded mass of the test
accordance with 6.1. Record the exact mass of each test
sample, m,, and multiplying by 100.
specimen to the nearest gram. Correct for coarse aggregate
% Water = (w/m,) x 100
variance by using the procedure in Section 19 when nominal
11.2.2 The computed water content can be expressed as
aggregate size exceeds 11/2 in.
Ib/yd3:
NOTE 3-A wide range of sample mass is allowed to prevent the
Water, Ibfyà3 = (w/ms)27W
mortar-aggregate ratio from being biased through the adjustment of the
sample size.
where:
w = computed water content of the test sample, g,
10.2 Place each specimen into individual wide-mouth
m = mass of the test sample, g, and
jars. Using a volumetric flask, add 500 mL of 0.5N NaCl
W = unit weight of the c
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