ASTM C1679-07
(Practice)Standard Practice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Isothermal Calorimetry
Standard Practice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Isothermal Calorimetry
SIGNIFICANCE AND USE
Thermal power curves are used to evaluate the isothermal hydration kinetics of the combined mixture of different materials during the early period after being mixed with water. These isothermal power curves, or hydration profiles, may provide indications relative to setting characteristics, compatibility of different materials, sulfate balance and early strength development. The isothermal hydration profiles can also be used to evaluate the effects of compositions, proportions, and time of addition of materials as well as curing temperature. Special care must be used in evaluating extended retardation with paste specimens, which have been shown to overestimate the retardation of some mixtures containing cement, SCM, and admixtures.
This procedure can be used to measure the effect of chemical admixtures on the cement hydration profile. In many cases, the addition of chemical admixture changes the kinetics of cement hydration.
Although this technique has been used historically to understand issues related to setting and slump loss, it must be emphasized that isothermal calorimetry results cannot predict concrete performance definitely, either positively or negatively. Extensive verification in concrete at planned dosages and temperatures, and at higher dosages, is needed. Isothermal calorimetry is an effective tool to identify sensitivities, so that concrete testing can be efficiently planned and performed.
This practice provides a means of assessing the relative hydration performance of various test mixtures compared with control mixtures that are prepared in a similar manner.
The procedure and apparatus can be used to monitor the thermal power from pastes and mortars alone or in combination with chemical admixtures.
The isothermal calorimeter described here can be used to measure the thermal power and heat of hydration of mortars prepared independently or obtained by wet sieving from concrete in accordance with Practice C 172.
SCOPE
1.1 This practice describes the apparatus and procedure for measuring relative differences in hydration kinetics of hydraulic cementitious mixtures, either in paste or mortar (See Note 1), including those containing admixtures, various supplementary cementitious materials (SCM), and other fine materials by measuring the thermal power using an isothermal calorimeter.
Note 1— Paste specimens are often preferred for mechanistic research when details of individual reaction peaks are important or for particular calorimetry configurations. Mortar specimens may give results that have better correlation with concrete setting and early strength development and are often preferred to evaluate different mixture proportions for concrete. Both paste and mortar studies have been found to be effective in evaluating concrete field problems due to incompatibility of materials used in concrete mixtures.
1.2 UnitsThe values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure. )
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C1679–07
Standard Practice for
Measuring Hydration Kinetics of Hydraulic Cementitious
Mixtures Using Isothermal Calorimetry
This standard is issued under the fixed designation C 1679; 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.
1. Scope C 305 PracticeforMechanicalMixingofHydraulicCement
Pastes and Mortars of Plastic Consistency
1.1 This practice describes the apparatus and procedure for
C 403/C 403M TestMethodforTimeofSettingofConcrete
measuring relative differences in hydration kinetics of hydrau-
Mixtures by Penetration Resistance
lic cementitious mixtures, either in paste or mortar (See Note
C511 Specification for Mixing Rooms, Moist Cabinets,
1), including those containing admixtures, various supplemen-
Moist Rooms, and Water Storage Tanks Used in the
tary cementitious materials (SCM), and other fine materials by
Testing of Hydraulic Cements and Concretes
measuring the thermal power using an isothermal calorimeter.
C 778 Specification for Standard Sand
NOTE 1—Paste specimens are often preferred for mechanistic research
C 1005 Specification for Reference Masses and Devices for
when details of individual reaction peaks are important or for particular
Determining Mass and Volume for Use in the Physical
calorimetry configurations. Mortar specimens may give results that have
Testing of Hydraulic Cements
better correlation with concrete setting and early strength development
C 1602/C 1602M Specification for Mixing Water Used in
and are often preferred to evaluate different mixture proportions for
concrete. Both paste and mortar studies have been found to be effective in the Production of Hydraulic Cement Concrete
evaluating concrete field problems due to incompatibility of materials
2.2 Other Standard:
used in concrete mixtures.
API Specification RP 10B-2/ ISO 10426-2 Recommended
Practice for Testing Well Cements
1.2 Units—The values stated in SI units are to be regarded
as standard. No other units of measurement are included in this
3. Terminology
standard.
3.1 Definitions—For definitions of terms used in this prac-
1.3 This standard does not purport to address all of the
tice, refer to Terminology C 125 and Terminology C 219.
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.2.1 baseline, n—the signal from the calorimeter when
priate safety and health practices and determine the applica-
there is an inert specimen in the instrument.
bility of regulatory limitations prior to use. (Warning—Fresh
3.2.2 calibration coeffıcient, n—a factor that relates the
hydraulic cementitious mixtures are caustic and may cause
value recorded by the data acquisition system to the thermal
chemical burns to skin and tissue upon prolonged exposure. )
power output.
2. Referenced Documents
3.2.2.1 Discussion—Normally recorded data are in volts
and the calibration coefficient has units of watts per volt
2.1 ASTM Standards:
(W/V). Some calorimeters may have internal automatic cali-
C 125 Terminology Relating to Concrete and Concrete
bration and will give the output in watts without the user
Aggregates
having to specify the calibration coefficient.
C 172 Practice for Sampling Freshly Mixed Concrete
3.2.3 combined mixture, n—combinationofallthematerials
C 219 Terminology Relating to Hydraulic Cement
that are introduced into the calorimeter for measuring hydra-
tion kinetics.
This practice is under the jurisdiction of ASTM Committee C09 on Concrete
3.2.4 hydration time, n—the elapsed time from initial con-
andConcreteAggregatesandisthedirectresponsibilityofSubcommitteeC09.48on
tact between the cementitious materials and the mix water.
Performance of Cementitious Materials and Admixture Combinations.
Current edition approved Nov. 1, 2007. Published December 2007.
3.2.5 inert specimen, n—specimen placed within the iso-
Section on Safety Precautions, Manual of Aggregate and Concrete Testing,
thermal calorimeter made of a non-reactive material of similar
Annual Book of ASTM Standards, Vol 04.02.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American Petroleum Institute (API), 1220 L. St., NW, Wash-
the ASTM website. ington, DC 20005-4070, http://api-ec.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1679–07
thermal properties (mainly heat capacity) as the reacting 3.2.14 sulfate balance of mixture, n—the situation when the
specimen made of the cementitious test mixture. size of the main hydration peak is not increased by sulfate
3.2.5.1 Discussion—The output from the calorimeter is the additions; in some cases where the main peak is increased in
differencebetweentheheatflowfromthetestspecimenandthe size by added sulfate, it will also be accelerated in time.
inert specimen. The use of an inert specimen substantially
3.2.15 sulfate depletion point, n—the onset of accelerated
decreases the noise and drift of the measured heat flow.
aluminate activity that for a portland cement in absence of
3.2.6 isothermal calorimeter, n—a calorimeter that mea-
supplementary cementitious material (SCM) and admixture
sures heat flow from a specimen maintained at a constant
may take place after the main hydration peak.
temperature by intimate thermal contact with a constant
3.2.15.1 Discussion—The sulfate depletion point may be-
temperature heat sink.
come impossible to detect without further addition of gypsum
3.2.7 isothermal calorimetry, n—an experimental technique
or plaster for certain cements and more often in combined
to monitor the thermal power output from a specimen kept at
mixtures with admixtures or SCMs, or both. In some cases
near isothermal conditions.
other sources of sulfate might be used to mimic potential
3.2.8 isothermal hydration profile, n—the thermal power
conditions in the system. Among these are anhydrite, arcanite,
plotted as a function of hydration time, which provides an
calcium langbeinite, aphthitalite, syngenite, and others. Fig. 2
indication of the rate of hydration over time at a given
shows an example of the effect of added sulfate on the sulfate
temperature.
depletion point. Added sulfate may, in some combined mix-
3.2.9 main hydration peak, n—the broadest peak in the
tures with admixtures or SCMs, or both, accelerate the onset of
isothermal hydration profile that starts at the end of the
the main hydration peak. When a combined mixture is at
dormant period and for a well-balanced mixture lasts for
sulfate balance, further addition of soluble sulfate will not
several hours (See Fig. 1).
increase the size, or accelerate the onset, of the main hydration
3.2.10 near isothermal conditions, n—a constant tempera-
peak.
ture with a permissible variation of 6 1.0 °C.
3.2.16 thermal equilibrium time, n—the elapsed hydration
3.2.11 specimen holder, n—container within the isothermal
timewhenthethermalpowerofreplicatemixturesdonotdiffer
calorimeterthatconductstheheatfromthespecimeninthevial
by more than 0.2 mW/g of dry material.
to the heat flow sensor.
3.2.17 thermal indicator of setting time, n—the hydration
3.2.12 stock solution, n—a solution of admixture in water
time to reach a thermal power of 50 % of the maximum value
prepared to enable more precise volumetric addition of small
of the main hydration peak.
quantities of admixture, typically made by pipetting known
3.2.18 thermal power, n—heat production rate measured in
volumes of admixture into a volumetric flask and diluting it to
watts (W) or joules per second (J/s), usually expressed in
the flask’s fixed volume.
relation to the mass of cementitious material, as mW/g or J/s/g.
3.2.13 sulfate addition, n—the addition of a soluble sulfate
source (such as gypsum, calcium sulfate hemihydrate, alkali 3.2.18.1 Discussion—The thermal power is an indicator of
sulfate) to a combined mixture to investigate whether a given the rate of various chemical reactions between cementitious
combination of materials is in sulfate balance.
materials, other fine particles, mix water and admixtures.
NOTE—(A) initial thermal power by dissolution of cement and initial cement hydration; (B) dormant period associated with very low thermal power
indicating slow and well-controlled hydration: (C) main hydration peak associated mainly with hydration reactions contributing to setting and early
strength development, with maximum at (D); and (E) sulfate depletion point, followed by (F) accelerated aluminate activity.
FIG. 1 Example of Thermal Power Curve for Isothermal Hydration of Portland Cement
C1679–07
FIG. 2 Example of the Effect of Soluble Calcium Sulfate Addition on the Timing of the Sulfate Depletion Point for a Type I Portland
Cement Mixed with Water Only at w/c = 0.45
3.2.19 vial, n—container into which the freshly mixed 5.2 This procedure can be used to measure the effect of
cementitious mixture is placed for a measurement. chemical admixtures on the cement hydration profile. In many
cases, the addition of chemical admixture changes the kinetics
4. Summary of Practice
of cement hydration.
4.1 An isothermal calorimeter consists of heat sink with a
5.3 Although this technique has been used historically to
thermostat, two heat flow sensors and a specimen vial holder
understand issues related to setting and slump loss, it must be
attached to each sensor. A vial containing a freshly prepared
emphasized that isothermal calorimetry results cannot predict
mixture is placed in contact with one of the vial holders and a
concreteperformancedefinitely,eitherpositivelyornegatively.
thermally inert material is placed in contact with the other.The
Extensive verification in concrete at planned dosages and
heat of hydration released by the reacting cementitious speci-
temperatures, and at higher dosages, is needed. Isothermal
men is transferred and passes across a heat flow sensor. The
calorimetry is an effective tool to identify sensitivities, so that
calorimeter output is calculated from the difference between
concrete testing can be efficiently planned and performed.
the outputs from the test specimen heat flow sensor and the
5.4 This practice provides a means of assessing the relative
inert specimen heat flow sensor. Because the heat is allowed to
hydration performance of various test mixtures compared with
flow away from the specimen, the measurement will take place
control mixtures that are prepared in a similar manner.
at essentially constant temperature (isothermal conditions).
5.5 The procedure and apparatus can be used to monitor the
4.2 Mixtures with cement, SCM, admixtures, water and
thermalpowerfrompastesandmortarsaloneorincombination
optional fine aggregate are prepared and introduced into an
with chemical admixtures.
isothermal calorimeter. Isothermal calorimetry tests are per-
5.6 The isothermal calorimeter described here can be used
formedonaseriesofdifferentmixturesforrelativecomparison
to measure the thermal power and heat of hydration of mortars
of the hydration kinetics. The output of the calorimeter is
prepared independently or obtained by wet sieving from
evaluated by graphical and mathematical means to evaluate
concrete in accordance with Practice C 172.
retarding and accelerating effects of different combinations of
materials. Calcium sulfate may be added as a probe to
6. Apparatus
determine if the addition of admixture, SCMs, or both have
6.1 Devices for mixing to produce a homogeneous mixture
increased the mixture’s demand for sulfate beyond that which
of cement, SCM, admixtures, water and optional other fine
is available in the cement.
materials or aggregate and devices for charging the mixture
5. Significance and Use
into the specimen vial.
6.1.1 Weights and Weighing Devices shall conform to the
5.1 Thermal power curves are used to evaluate the isother-
requirements of Specification C 1005.
mal hydration kinetics of the combined mixture of different
materials during the early period after being mixed with water. 6.1.2 Graduated Cylinders shall conform to the require-
ments of Specification C 1005. The permissible variation for
These isothermal power curves, or hydration profiles, may
provide indications relative to setting characteristics, compat- graduated cylinders of less than 100-mL capacity shall be
61.0 % of the rated capacity.
ibility of different materials, sulfate balance and early strength
development. The isothermal hydration profiles can also be 6.1.3 Graduated Syringes of suitable capacities to contain
used to evaluate the effects of compositions, proportions, and the desired volume of liquid admixture or stock solution at 20
time of addition of materials as well as curing temperature. °C.The permissible variation of the measured volume shall not
Special care must be used in evaluating extended retardation exceed 3 % of the volume to be delivered. When admixture
with paste specimens, which have been shown to overestimate quantities required are less than 2 mL, or are viscous in nature,
the retardation of some mixtures containing cement, SCM, and prepare stock solutions at appropriate dilution, to avoid prob-
admixtures. lems with small volumes measured volumetrically. Care shall
C1679–07
be taken to inspect stock solutions for separation and any 6.2.4 The data acquisition equipment shall be capable of
admixture that is prone to separation in stock solution must be performing continuous logging of the calorimeter output with
added in an alternative fashion, such as by analytical syringes. a time interval between the measurements that is no larger than
60 s.
6.1.4 Mixing Apparatus:
6.1.4.1 Mortar Preparation—The mixer shall comply with
7. Materials
Practice C 305.
7.1 Sand:
6.1.4.2 Paste Preparation—A high shear blender, or simi-
7.1.1 Unless specified otherwise, use standard graded sand
lar variable speed blender capable of maintaining a no-load
asdefinedinSpecificationC 778forpreparingmortarsamples.
speed of at least 15 000 r/min, with optional cooling device.A
7.1.2 When specified, use job-specific sand when perform-
handheld household mixer capable of mixing paste at not less
ing a specific mortar test series that is related to field
than 400 r/min or other mixers for paste or mortar preparation
application.
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.