1、Designation: C1702 13aStandard 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 adoption
2、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 procedurefor determining total
3、heat of hydration of hydraulic cementi-tious materials at test ages up to 7 days by isothermalconduction calorimetry.1.2 This test method also outputs data on rate of heat ofhydration versus time that is useful for other analyticalpurposes, as covered in Practice C1679.1.3 The values stated in SI un
4、its are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health pra
5、ctices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C186 Test Method for Heat of Hydration of HydraulicCementC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC1679 Practice for Me
6、asuring Hydration Kinetics of Hy-draulic Cementitious Mixtures Using Isothermal Calorim-etryE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 baseline, nthe time-series signal from th
7、e calorim-eter when measuring output from a sample of approximatelythe same mass and thermal properties as a cement sample, butwhich is not generating or consuming heat.3.1.2 heat, nthe time integral of thermal power measuredin joules (J).3.1.3 isothermal conduction calorimeter, na calorimeterthat m
8、easures heat flow from a sample maintained at a constanttemperature by intimate thermal contact with a constanttemperature heat sink.3.1.4 reference cell, na heat-flow measuring cell that isdedicated to measuring power from a sample that is generatingno heat.3.1.4.1 DiscussionThe purpose of the refe
9、rence cell is tocorrect for baseline drift and other systematic errors that canoccur in heat-flow measuring equipment.3.1.5 sensitivity, nthe minimum change in thermal powerreliably detectable by an isothermal calorimeter.3.1.5.1 DiscussionFor this application, sensitivity is takenas ten times the r
10、andom noise (standard deviation) in thebaseline signal.3.1.6 thermal mass, nthe ability of a material to storethermal energy (J/K).3.1.6.1 DiscussionThe thermal mass of a given material iscalculated by multiplying the mass by the specific heat capacityof the material. The specific heat capacity of a
11、 typical portlandcement and water is 0.75 and 4.18 J/g/K, respectively.3.1.7 thermal power, nthe heat production rate measuredin joules per second (J/s).3.1.7.1 DiscussionThis is the property measured by thecalorimeter. The thermal power unit of measure is J/s, which isequivalent to the watt. The wa
12、tt is also a common unit ofmeasure used to represent thermal power.4. Summary of Test Method4.1 PrincipleAn isothermal heat conduction calorimeterconsists of a constant-temperature heat sink to which twoheat-flow sensors and sample holders are attached in a mannerresulting in good thermal conductivi
13、ty. One heat-flow sensorand sample holder contains the sample of interest. The other1This test method is under the jurisdiction ofASTM Committee C01 on Cementand is the direct responsibility of Subcommittee C01.26 on Heat of Hydration.Current edition approved Dec. 15, 2013. Published February 2014.
14、Originallyapproved in 2009. Last previous edition approved in 2013 as C170213. DOI:10.1520/C1702-13A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards D
15、ocument Summary page onthe ASTM website.*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 States1heat-flow sensor is a reference cell containing a blank samplethat evolves no hea
16、t. The heat of hydration released by thereacting cementitious sample flows across the sensor and intothe heat sink. The output from the calorimeter is the differencein heat flow (thermal power) between the sample cell and thereference cell. The heat-flow sensor actually senses a smalltemperature gra
17、dient that develops across the device, howeverthe heat is removed from the hydrating sample fast enoughthat, for practical purposes, the sample remains at a constanttemperature (isothermal).4.2 The output from the heat-flow sensor is an electricalvoltage signal that is proportional to the thermal po
18、wer fromthe sample. This output must be calibrated to a known thermalpower. In this method this is accomplished by measurementson a heat source that emits a constant and known thermalpower. The integral of the thermal power over the time of thetest is the heat of hydration. Alternatively, a cementit
19、iousmaterial with a known heat of hydration can be used forcalibration as described in Appendix X1.4.3 Two methods are described. In MethodAthe sample andwater are both temperature equilibrated and mixed inside thecalorimeter. This method is the most direct way to determineheat of hydration. In Meth
20、od B the sample is mixed in thesample vial outside of the calorimeter using temperatureequilibrated materials then put into the calorimeter. Thismethod offers certain practicality, but depending on the mate-rials being analyzed and procedures used for mixing andhandling, this method may suffer from
21、small errors due toperiods of hydration being missed or spurious heat beingintroduced or taken away from the calorimeter during setup orcombinations thereof.5. Significance and Use5.1 This method is suitable for determining the total heat ofhydration of hydraulic cement at constant temperature at ag
22、esup to 7 days to confirm specification compliance. It gives testresults equivalent to Test Method C186 up to 7 days of age(Poole (2007) (1).5.2 This method compliments Practice C1679 by providingdetails of calorimeter equipment, calibration, and operation.Practice C1679 emphasizes interpretation si
23、gnificant events incement hydration by analysis of time dependent patterns ofheat flow, but does not provide the level of detail necessary togive precision test results at specific test ages required forspecification compliance.6. Apparatus6.1 Miscellaneous Equipment:6.1.1 BalanceAccurate to 0.01 g.
24、6.1.2 Volumetric DispenserA device for measuring vol-ume or mass of water, accurate to 0.1 mL. This could be asyringe, pipette, or weighing device.6.1.3 Sample HolderA device that holds the cement pasteand provides intimate contact with the calorimeter heat sensingdevice and prevents evaporation of
25、mixing water. If usingcommercially manufactured equipment, consult the recom-mendations of the manufacturer in choosing sample holders.6.1.4 Resistance HeaterAn electrical device fabricatedfrom material with similar heat capacity and shape as the testsample, but containing a resistor connected to a
26、constant-voltage power supply such that a stable output of 0.010 60.0002 J/s can be generated (see Note 1).NOTE 1A simple procedure for fabricating heaters and blanks havingthe same approximate shape and heat capacity as a sample is to makespecimen similar to one used in a determination out of plast
27、er of Parisembedded with a small resistor. Plaster of Paris has only a transient heatof hydration and is not aggressive to electronic components. A resistanceof 100-300 ohms is a convenient value when using voltages of 0.1-10volts to drive heat production.6.1.5 Reference SpecimenA sample fabricated
28、from aninert material with similar heat capacity and shape as the testsample. This is used in the reference cell.6.1.6 MultimeterAn instrument for measuring DC voltageand resistance values for the resistance heater described in6.1.4 to an accuracy of 1 %. This instrument is only required ifthe calor
29、imeter does not contain built-in calibration capability.6.1.7 Power SupplyA constant voltage DC power supplywith a power output range sufficient to simulate the maximumoutput of a hydrating cement sample (see Note 2). Thisequipment is only required if an instrument does not containbuilt-in calibrati
30、on capability.NOTE 2A power output of at least 0.33 J/s is needed for mostapplications.6.2 CalorimeterThe schematic design of a calorimeter isgiven in Fig. 1. It shall consist of a sample holder for the testand reference specimens, each thermally connected to heatFIG. 1 Schematic Drawing of a Heat C
31、onduction CalorimeterC1702 13a2flow sensors, which are thermally connected to a constant-temperature heat sink. The actual design of an individualinstrument, whether commercial or homemade, may vary, butit should follow the criteria given below. Any other suitablearrangement that satisfies sections
32、6.2.1, 6.2.2, and 6.2.3 isacceptable.6.2.1 Instrument StabilityThe baseline shall exhibit a lowrandom noise level and be stable against drift. This propertyshall be verified on a new instrument and whenever there arequestions about performance. The rate of change of thebaseline measured during a tim
33、e period of 3 days shall be 20J/s per gram sample per hour of the test and a baseline randomnoise level of 10 J/s per gram sample (see Note 3). Inpractice the baseline is measured for 3 days and a straight lineis fitted to the power (J/g/s) versus time (h) data using a linearregression procedure. Th
34、e long term drift is then the slope inthe line J/g/s/h and the baseline noise level is the standarddeviation (J/g/s) around this regression line.NOTE 3The rationale for these limits is found in Poole (2007) (1).6.2.2 Instrument SensitivityThe minimum sensitivity formeasuring power output shall be 10
35、0 J/s.6.2.3 Isothermal ConditionsThe instrument shall maintainthe temperature of the sample to within 1 K of the thermostatedtemperature.6.3 Data Acquisition EquipmentData acquisition equip-ment may be built into the calorimeter instrument package, orit may be an off-the-shelf, stand-alone, item. Th
36、e data acqui-sition equipment shall be capable of performing continuouslogging of the calorimeter output measurement at a minimumtime interval of 10 s. It is useful, for purposes of reducingamount of data, to have the flexibility to adjust the readinginterval to longer times when power output from t
37、he sample islow. Some data acquisition equipment is designed to automati-cally adjust reading intervals in response to power output. Theequipment shall have at least 4.5-digit-measuring capability,with an accuracy of 1 %, or comparable capabilities to condi-tion the power output into the same qualit
38、y as integrated signalamplifiers.7. Instrument Calibration7.1 Instrument CalibrationCommercially manufacturedinstruments designed for measuring heat of hydration ofcementitious materials may have instrument specific calibra-tion procedures. Conform to these procedures if they exist. Inaddition, the
39、instrument shall be capable of providing datadescribed in 7.1.1.1, 7.1.2.1, and 7.1.2.2, and calculations in7.1.4. If there are no instrument calibration procedures, cali-brate the instrument according to the following procedure.Calibration shall be at least a two-point process. This isillustrated s
40、chematically in Fig. 2 Alternatively use a genericcalibration procedure for a cementitious material with knownheat of hydration as described in Appendix X1. Alternatively,use a generic calibration procedure for a cementitious materialwith known heat of hydration as described in Appendix X1.7.1.1 Mou
41、nt the resistance heater and the blank specimen intheir respective measuring cells and start data collection. Thisstep measures the baseline calorimeter output (in units of V ormV) when no heat is being generated.7.1.1.1 Measure this baseline when it reaches a constantvalue (drift 20 J/s per gram sa
42、mple per hour).7.1.1.2 Record this output as V0for P0= 0 (see Note 4).NOTE 4V0may not be zero voltage, but may be a positive or negativenumber.The practice of using a test cell and a reference cell usually resultsin the V0being a relatively small number but, depending on the variabilityin properties
43、 of some hardware, it may not be zero.FIG. 2 (A) Schematic Steady-State Calibration Using A 2-Point Calibration Process And (B) Multi-Point Calibration ProcessC1702 13a37.1.2 Power in the heater circuit is related to voltage andresistance by the following equation:P 5 I2R (1)where:P = power, J/s,I =
44、 applied current, amperes, andR = resistance, ohms.Apply sufficient voltage to the heater circuit to generate aheat output of approximately 0.1 J/s, measured to an accuracyof 5 %.7.1.2.1 Allow the output to stabilize signal at a drift of0.1 % over 60 min or 0.05 % over 30 min.7.1.2.2 Record this out
45、put as V1for 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 usedto characterize the operating range of the calorimeter.NOTE 5The early C3A reaction of a typical portland cement evolvesa maximum power of abo
46、ut 0.02 J/s/g. The alite phase typically evolvesheat at a maximum power of about 0.002 J/s/g during the first 24 h ofhydration. A5 g sample then generates power peaks in the range of 0.10J/s/g in the first few minutes after adding water, and in the range of 0.010J/s/g in the first 24 h.7.1.3 Calibra
47、tion CoeffcientsCalculate calibration coeffi-cients by fitting the power versus voltage output data to a to amathematical relationship using standard curve fitting tech-niques. Power (P), in units of J/s (or watts), is the dependentvariable (y) in the calibration equation, and output voltage (V),in
48、units of mV, is the independent variable (x). This equation isthen used to translate mV output to power units meaningful forcalculating heat flow (see Note 6).NOTE 6A linear calibration equation is found to be suitable in manyinstruments over the operating range necessary to analyze portlandcements,
49、 as in the following equation: P = A + BV. In this case, the fittedcoefficients A (y-axis intercept) and B (slope) are in units of J/s andJ/s/mV, respectively.7.1.4 In a multi-channel instrument containing severalcalorimeters, all channels shall be calibrated individually.However, it is possible to calibrate all calorimeters simultane-ously using multiple resistance heaters and having the samecurrent passing through the heaters in all calorimeter cells.7.1.5 Calibration shall be executed at regular intervals todetermine the calibration co
