1、Designation: C1702 15aC1702 15bStandard 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
2、adoption 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 determin
3、ing 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 state
4、d 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 an
5、d 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 CementC1679 Practice for Measuring Hydration Kinetics of Hydraulic Cementitious Mixtures Using Isothermal Calorimetr
6、yE691 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 signal from the calorimeter when measuring output from a sample of approximately the samemass and therma
7、l 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 calorimeter that measures heat flow from a sample maintained at a constanttemperature by intimate thermal
8、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 purpose of the reference cell is to correct for baseline drift and other systematic errors that can occu
9、r 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 jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.26 on Heat of
10、 Hydration.Current edition approved Aug. 1, 2015Dec. 1, 2015. Published August 2015January 2016. Originally approved in 2009. Last previous edition approved in 2015 asC1702 15.C1702 15a. DOI: 10.1520/C1702-15A.10.1520/C1702-15B.2 For referencedASTM standards, visit theASTM website, www.astm.org, or
11、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 and is intended only to provide the user of an ASTM standard an indication of what changes have
12、 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 only the current versionof the standard as published by ASTM is to be considered the official docu
13、ment.*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, sensitivity is taken as ten times the random noise (standard deviation) in the baseline signal
14、.3.1.6 thermal mass, nthe amount of thermal energy that can be stored by a material (J/K).3.1.6.1 DiscussionThe thermal mass of a given material is calculated by multiplying the mass by the specific heat capacity of the material. For thepurpose of calculating the thermal mass used in this standard,
15、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/(gK), respectively. Thus a mixture of A g of cementand B g of water has a thermal mass of (0.75 A + 4.18 B) J/K. The specific heat capacity of typical qu
16、artz and limestone is0.75 and 0.84 J(gK), respectively. The specific heat capacity of most amorphous supplementary cementitious material, such asfly 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 t
17、he property measured by the calorimeter. The thermal power unit of measure is J/s, which is equivalent to the watt. Thewatt is also a common unit of measure used to represent thermal power.4. Summary of Test Method4.1 PrincipleAn isothermal heat conduction calorimeter consists of a constant-temperat
18、ure heat sink to which two heat-flowsensors and sample holders are attached in a manner resulting in good thermal conductivity. One heat-flow 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 hea
19、t of hydration released by the reacting cementitious sample flows across the sensor and into the heat sink. The output fromthe calorimeter 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 t
20、hat develops across the device, however the heat is removed from the hydratingsample fast enough that, for practical purposes, the sample remains 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
21、from thesample. This output must be calibrated to a known thermal power. In this method this is accomplished by measurements on a heatsource 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 cementitio
22、us material with a known heat of hydration can be used for calibration as described inAppendix X1.4.3 Two methods are described. In Method 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 M
23、ethod B the sample is mixed in the samplevial outside of the calorimeter using temperature equilibrated materials then put into the calorimeter. This method offers certainpracticality, but depending on the materials being analyzed and procedures used for mixing and handling, this method may sufferfr
24、om small errors due to periods of hydration being missed or spurious heat being introduced or taken away from the calorimeterduring setup or combinations thereof.5. Significance and Use5.1 This method is suitable for determining the total heat of hydration of hydraulic cement at constant temperature
25、 at ages upto 7 days to confirm specification compliance. It gives test results equivalent to Test Method C186 up to 7 days of age (1).35.2 This method compliments Practice C1679 by providing details of calorimeter equipment, calibration, and operation. PracticeC1679 emphasizes interpretation signif
26、icant events in cement hydration by analysis of time dependent patterns of heat flow, butdoes not provide the level of detail necessary 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
27、.1.2 Volumetric DispenserA device for measuring volume or mass of water, accurate to 0.1 mL. This could be a syringe,pipette, or 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 m
28、ixing water. If using commercially manufactured equipment, consult the recommendationsof the manufacturer in choosing sample holders.3 The boldface numbers in parentheses refer to the list of references at the end of this standard.C1702 15b26.1.4 Resistance HeaterAn electrical device fabricated from
29、 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 procedure for fabricating heaters and blanks having the same approximate
30、 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 to electronic components.Aresistance of 100 to 300 is a convenient value
31、 when using voltages of 0.1 to 10 V to drive heat production.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.6.1.6 MultimeterAn instrument for measuring DC voltage and resistance values for
32、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 power output range sufficient to simulate the maximum outputof a hydrating ce
33、ment 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 schematic design of a calorimeter is given in Fig. 1. It shall consist of a sample h
34、older 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 or homemade, may vary, but it should follow the criteriagiven below. Any other
35、 suitable arrangement that satisfies sections 6.2.1 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 on a new instrument and whenever there are questions about performance. The rate of change
36、 of the baseline measuredduring a time period of 3 days shall be 20 Js 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 measured for 3 days and a straight line is fitted to the power (J/(gs)versus time (h) data
37、using a linear regression procedure. The long term drift is then the slope in the line (J/(gsh) and the baselinenoise level is the standard deviation (J/(gs) around this regression line.NOTE 3The rationale for these limits is found in Poole (2007) (1).6.2.2 Instrument SensitivityThe minimum sensitiv
38、ity 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 Acquisition EquipmentData acquisition equipment may be built into the calorimeter instrument package, or it may
39、be 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 10 s. It is useful, for purposes of reducing amount of data, to havethe flexibility to adjust the reading interv
40、al 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 shall have at least4.5-digit-measuring capability, with an accuracy of 1 %, or comparable capabilities to condi
41、tion the power output into the samequality as integrated signal amplifiers.7. Instrument Calibration7.1 Instrument CalibrationCommercially manufactured instruments designed for measuring heat of hydration of cementitiousmaterials may have instrument specific calibration procedures. Conform to these
42、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 calibration procedures, calibrate the instrument according to the following procedure. Calibration shall be at leas
43、t atwo-point process. This is illustrated schematically in Fig. 2 Alternatively use a generic calibration procedure for a cementitiousFIG. 1 Schematic Drawing of Heat Conduction CalorimeterC1702 15b3material with known heat of hydration as described in Appendix X1. Alternatively, use a generic calib
44、ration 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 cells and start data collection. This stepmeasures the baseline calorimeter output (in units of V or mV) when no
45、 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).NOTE 4V0 may not be zero voltage, but may be a positive or negative number. The practice of using a test cell and a
46、 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.7.1.2 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 cu
47、rrent, amperes, andR = resistance, ohms.Apply sufficient voltage 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 V
48、1 for a power P1 (see Note 5). This is the minimum requirement 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
49、 0.02 J/(gs). The alite phase typically evolves heatat a maximum power of about 0.002 J/(gs) during the first 24 h of hydration. A 5-g sample then generates power peaks in the range of 0.10 J s in thefirst few minutes after adding water, and in the range of 0.010 J s in the first 24 h.7.1.3 Calibration CoeffcientsCalculate calibration coefficients by fitting the power versus voltage output data to a to amathematical relationship using standard curve fitting techniques. Power (P), in units of J/s (or watts), is th
