1、Designation: C1702 13aC1702 14Standard Test Method forMeasurement of Heat of Hydration of HydraulicCementitious Materials Using Isothermal ConductionCalorimetry1This standard is issued under the fixed designation C1702; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method specifies the apparatus and procedure for determini
3、ng total heat of hydration of hydraulic cementitiousmaterials at test ages up to 7 days by isothermal conduction calorimetry.1.2 This test method also outputs data on rate of heat of hydration versus time that is useful for other analytical purposes, ascovered in Practice C1679.1.3 The values stated
4、 in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and
5、 health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C186 Test Method for Heat of Hydration of Hydraulic CementC670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction MaterialsC1679 Prac
6、tice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Isothermal CalorimetryE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 baseline, nthe time-series sign
7、al from the calorimeter when measuring output from a sample of approximately the samemass and thermal properties as a cement sample, but which is not generating or consuming heat.3.1.2 heat, nthe time integral of thermal power measured in joules (J).3.1.3 isothermal conduction calorimeter, na calori
8、meter that measures heat flow from a sample maintained at a constanttemperature by intimate thermal contact with a constant temperature heat sink.3.1.4 reference cell, na heat-flow measuring cell that is dedicated to measuring power from a sample that is generating no heat.3.1.4.1 DiscussionThe purp
9、ose of the reference cell is to correct for baseline drift and other systematic errors that can occur in heat-flow measuringequipment.3.1.5 sensitivity, nthe minimum change in thermal power reliably detectable by an isothermal calorimeter.3.1.5.1 Discussion1 This test method is under the jurisdictio
10、n of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.26 on Heat of Hydration.Current edition approved Dec. 15, 2013July 15, 2014. Published February 2014August 2014. Originally approved in 2009. Last previous edition approved in 2013 asC170213.13a. DOI: 10.1520/C170
11、2-13A.10.1520/C1702-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard
12、and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases onl
13、y the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1For this application,
14、 sensitivity is taken as ten times the random noise (standard deviation) in the baseline signal.3.1.6 thermal mass, nthe ability of a material to store thermal energy amount of thermal energy that can be stored by amaterial (J/K).3.1.6.1 DiscussionThe thermal mass of a given material is calculated b
15、y multiplying the mass by the specific heat capacity of the material. For thepurpose of calculating the thermal mass used in this standard, the following specific heat capacities can be used: The specific heatcapacity of a typical unhydrated portland cement and water is 0.75 and 4.18 J/g/K, respecti
16、vely.J/(gK), respectively. Thus amixture of A g of cement and B g of water has a thermal mass of (0.75 A + 4.18 B) J/K. The specific heat capacity of typicalquartz and limestone is 0.75 and 0.84 J/(gK), respectively. The specific heat capacity of most amorphous supplementarycementitious material, su
17、ch as fly ash or slag, is approximately 0.8 J/(gK).3.1.7 thermal power, nthe heat production rate measured in joules per second (J/s).3.1.7.1 DiscussionThis is the property measured by the calorimeter. The thermal power unit of measure is J/s, which is equivalent to the watt. Thewatt is also a commo
18、n unit of measure used to represent thermal power.4. Summary of Test Method4.1 PrincipleAn isothermal heat conduction calorimeter consists of a constant-temperature heat sink to which two heat-flowsensors and sample holders are attached in a manner resulting in good thermal conductivity. One heat-fl
19、ow sensor and sampleholder contains the sample of interest. The other heat-flow sensor is a reference cell containing a blank sample that evolves no heat.The heat of hydration released by the reacting cementitious sample flows across the sensor and into the heat sink. The output fromthe calorimeter
20、is the difference in heat flow (thermal power) between the sample cell and the reference cell. The heat-flow sensoractually senses a small temperature gradient that develops across the device, however the heat is removed from the hydratingsample fast enough that, for practical purposes, the sample r
21、emains at a constant temperature (isothermal).4.2 The output from the heat-flow sensor is an electrical voltage signal that is proportional to the thermal power from thesample. This output must be calibrated to a known thermal power. In this method this is accomplished by measurements on a heatsourc
22、e that emits a constant and known thermal power. The integral of the thermal power over the time of the test is the heat ofhydration. Alternatively, a cementitious material with a known heat of hydration can be used for calibration as described inAppendix X1.4.3 Two methods are described. In Method
23、A the sample and water are both temperature equilibrated and mixed inside thecalorimeter. This method is the most direct way to determine heat of hydration. In Method B the sample is mixed in the samplevial outside of the calorimeter using temperature equilibrated materials then put into the calorim
24、eter. This method offers certainpracticality, but depending on the materials being analyzed and procedures used for mixing and handling, this method may sufferfrom small errors due to periods of hydration being missed or spurious heat being introduced or taken away from the calorimeterduring setup o
25、r combinations thereof.5. Significance and Use5.1 This method is suitable for determining the total heat of hydration of hydraulic cement at constant temperature at ages upto 7 days to confirm specification compliance. It gives test results equivalent toTest Method C186 up to 7 days of age (Poole (2
26、007)(1).5.2 This method compliments Practice C1679 by providing details of calorimeter equipment, calibration, and operation. PracticeC1679 emphasizes interpretation significant events in cement hydration by analysis of time dependent patterns of heat flow, butdoes not provide the level of detail ne
27、cessary to give precision test results at specific test ages required for specification compliance.6. Apparatus6.1 Miscellaneous Equipment:6.1.1 BalanceAccurate to 0.01 g.6.1.2 Volumetric DispenserA device for measuring volume or mass of water, accurate to 0.1 mL. This could be a syringe,pipette, or
28、 weighing device.6.1.3 Sample HolderA device that holds the cement paste and provides intimate contact with the calorimeter heat sensingdevice and prevents evaporation of mixing water. If using commercially manufactured equipment, consult the recommendationsof the manufacturer in choosing sample hol
29、ders.C1702 1426.1.4 Resistance HeaterAn electrical device fabricated from material with similar heat capacity and shape as the test sample,but containing a resistor connected to a constant-voltage power supply such that a stable output of 0.010 6 0.0002 J/s can begenerated (see Note 1).NOTE 1Asimple
30、 procedure for fabricating heaters and blanks having the same approximate shape and heat capacity as a sample is to make specimensimilar to one used in a determination out of plaster of Paris embedded with a small resistor. Plaster of Paris has only a transient heat of hydration andis not aggressive
31、 to electronic components. A resistance of 100-300 ohms is a convenient value when using voltages of 0.1-10 volts to drive heatproduction.6.1.5 Reference SpecimenA sample fabricated from an inert material with similar heat capacity and shape as the test sample.This is used in the reference cell.6.1.
32、6 MultimeterAn instrument for measuring DC voltage and resistance values for the resistance heater described in 6.1.4to an accuracy of 1 %. This instrument is only required if the calorimeter does not contain built-in calibration capability.6.1.7 Power SupplyAconstant voltage DC power supply with a
33、power output range sufficient to simulate the maximum outputof a hydrating cement sample (see Note 2). This equipment is only required if an instrument does not contain built-in calibrationcapability.NOTE 2A power output of at least 0.33 J/s is needed for most applications.6.2 CalorimeterThe schemat
34、ic design of a calorimeter is given in Fig. 1. It shall consist of a sample holder for the test andreference specimens, each thermally connected to heat flow sensors, which are thermally connected to a constant-temperature heatsink. The actual design of an individual instrument, whether commercial o
35、r homemade, may vary, but it should follow the criteriagiven below. Any other suitable arrangement that satisfies sections 6.2.1, 6.2.2, and 6.2.3 is acceptable.6.2.1 Instrument StabilityThe baseline shall exhibit a low random noise level and be stable against drift. This property shallbe verified o
36、n a new instrument and whenever there are questions about performance. The rate of change of the baseline measuredduring a time period of 3 days shall be 20 J/s per gram sample per hour of the test and a baseline random noise level of 10J/s per gram sample (see Note 3). In practice the baseline is m
37、easured for 3 days and a straight line is fitted to the power(J/g/s)(J/(gs) versus time (h) data using a linear regression procedure. The long term drift is then the slope in the lineJ/g/s/h(J/(gsh) and the baseline noise level is the standard deviation (J/g/s)(J/(gs) around this regression line.NOT
38、E 3The rationale for these limits is found in Poole (2007) (1).6.2.2 Instrument SensitivityThe minimum sensitivity for measuring power output shall be 100 J/s.6.2.3 Isothermal ConditionsThe instrument shall maintain the temperature of the sample to within 1 K of the thermostatedtemperature.6.3 Data
39、Acquisition EquipmentData acquisition equipment may be built into the calorimeter instrument package, or it maybe an off-the-shelf, stand-alone, item. The data acquisition equipment shall be capable of performing continuous logging of thecalorimeter output measurement at a minimum time interval of 1
40、0 s. It is useful, for purposes of reducing amount of data, to havethe flexibility to adjust the reading interval to longer times when power output from the sample is low. Some data acquisitionequipment is designed to automatically adjust reading intervals in response to power output. The equipment
41、shall have at least4.5-digit-measuring capability, with an accuracy of 1 %, or comparable capabilities to condition the power output into the samequality as integrated signal amplifiers.7. Instrument Calibration7.1 Instrument CalibrationCommercially manufactured instruments designed for measuring he
42、at of hydration of cementitiousmaterials may have instrument specific calibration procedures. Conform to these procedures if they exist. In addition, theinstrument shall be capable of providing data described in 7.1.1.1, 7.1.2.1, and 7.1.2.2, and calculations in 7.1.4. If there are noinstrument cali
43、bration procedures, calibrate the instrument according to the following procedure. Calibration shall be at least aFIG. 1 Schematic Drawing of a Heat Conduction CalorimeterC1702 143two-point process. This is illustrated schematically in Fig. 2 Alternatively use a generic calibration procedure for a c
44、ementitiousmaterial with known heat of hydration as described in Appendix X1. Alternatively, use a generic calibration procedure for acementitious material with known heat of hydration as described in Appendix X1.7.1.1 Mount the resistance heater and the blank specimen in their respective measuring
45、cells and start data collection. This stepmeasures the baseline calorimeter output (in units of V or mV) when no heat is being generated.7.1.1.1 Measure this baseline when it reaches a constant value (drift 20 J/s per gram sample per hour).7.1.1.2 Record this output as V0 for P0 = 0 (see Note 4).NOT
46、E 4V0 may not be zero voltage, but may be a positive or negative number. The practice of using a test cell and a reference cell usually resultsin the V0 being a relatively small number but, depending on the variability in properties of some hardware, it may not be zero.FIG. 2 (A) Schematic Steady-St
47、ate Calibration Using A 2-Point Calibration Process And (B) Multi-Point Calibration ProcessC1702 1447.1.2 Power in the heater circuit is related to voltage and resistance by the following equation:P 5I2R (1)where:P = power, J/s,I = applied current, amperes, andR = resistance, ohms.Apply sufficient v
48、oltage to the heater circuit to generate a heat output of approximately 0.1 J/s, measured to an accuracy of 5 %.7.1.2.1 Allow the output to stabilize signal at a drift of 0.1 % over 60 min or 0.05 % over 30 min.7.1.2.2 Record this output as V1 for a power P1 (see Note 5). This is the minimum require
49、ment for a calibration sequence. Atthe users discretion any number of voltage levels may be used to characterize the operating range of the calorimeter.NOTE 5The early C3A reaction of a typical portland cement evolves a maximum power of about 0.02 J/s/g.J/(gs). The alite phase typically evolvesheat at a maximum power of about 0.002 J/s/gJ/(gs) during the first 24 h of hydration. A5A 5 g sample then generates power peaks in the range of 0.10J/s/gJ/s in the first few minutes after adding water, and in the range of 0.010 J/
