1、Designation: C1702 09aStandard 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-etry3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 baseline, nthe time-series signal from the calorim-eter when measuring output from a sample of approximatelythe same mass and thermal pro
7、perties 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 measures heat flow from a sample maintained at a constanttemperature by intimate thermal contact
8、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 reference cell is tocorrect for baseline drift and other systematic errors that canoccur in heat-flo
9、w 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 random noise (standard deviation) in thebaseline signal.3.1.6 thermal power, nthe heat production
10、 rate measuredin joules per second (J/s).3.1.6.1 DiscussionThis is the property measured by thecalorimeter. The thermal power unit of measure is J/s, which isequivalent to the watt. The watt is also a common unit ofmeasure used to represent thermal power.4. Summary of Test Method4.1 PrincipleAn isot
11、hermal 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 conductivity. One heat-flow sensorand sample holder contains the sample of interest. The otherheat-flow sensor is a refere
12、nce cell containing a blank samplethat evolves no heat. 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 he
13、at-flow sensor actually senses a smalltemperature gradient that develops across the device, howeverthe heat is removed from the hydrating sample fast enough1This test method is under the jurisdiction of ASTM Committee C01 on Cementand is the direct responsibility of Subcommittee C01.26 on Heat of Hy
14、dration.Current edition approved Dec. 1, 2009. Published January 2010. Originallyapproved in 2009. Last previous edition approved in 2009 as C170209. DOI:10.1520/C1702-09a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
15、nual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.that, fo
16、r 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 power fromthe sample. This output must be calibrated to a known thermalpower. In this method this is accomplished
17、 by measurementson a heat source that emits a constant and known power level.The integral of the thermal power over the time of the test is theheat of hydration.4.3 Two methods are described. In MethodAthe sample andwater are both temperature equilibrated and mixed inside thecalorimeter. This method
18、 is the most direct way to determineheat of hydration. In Method B the sample is mixed outside ofthe calorimeter then put into the calorimeter. This methodoffers certain practicality, but depending on the materials beinganalyzed and procedures used for mixing and handling, thismethod may suffer from
19、 small errors due to periods ofhydration being missed or spurious heat being introduced ortaken away from the calorimeter during setup or combinationsthereof. Methods of correction are offered for these potentialerrors.5. Significance and Use5.1 This method is suitable for determining the total heat
20、 ofhydration of hydraulic cement at constant temperature at agesup to 7 days to confirm specification compliance. It gives testresults equivalent to Test Method C186 up to 7 days of age(Poole (2007) (4).5.2 This method compliments Practice C1679 by providingdetails of calorimeter equipment, calibrat
21、ion, and operation.Practice C1679 emphasizes interpretation significant 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. Apparat
22、us6.1 Miscellaneous Equipment:6.1.1 BalanceAccurate to 0.01 g.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 t
23、he calorimeter heat sensingdevice and prevents evaporation of 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 shap
24、e as the testsample, but containing a resistor connected to a 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 ma
25、kespecimen similar to one used in a determination out of plaster 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 driv
26、e heat production.6.1.5 Reference SpecimenA sample fabricated 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
27、 accuracy of 1 %. This instrument is only required ifthe calorimeter 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 onl
28、y required if an instrument does not containbuilt-in calibration capability.NOTE 2A power output of at least 0.33 J/s is needed for mostapplications.6.1.8 Insulated ContainerUsed in the Method B de-scribed in 8.3.5.1. This device can be fabricated using a 500mL (approximate volume) container insulat
29、ed with at least 30mm of polystyrene on the sides and top.6.1.9 Temperature Measuring DeviceUsed in Method Bdescribed in 8.3.5.1. The device shall be capable of measuringtemperature changes to the nearest 0.1 C and of a physicalconfiguration that allows it to operate in the confines of theinsulated
30、container described in 6.1.8.6.2 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 heatflow sensors, which are thermally connected to a constant-temperature heat sink. The actual de
31、sign of an individualFIG. 1 Schematic Drawing of a Heat Conduction CalorimeterC1702 09a2instrument, whether commercial or homemade, may vary, butit should follow the criteria given below. Any other suitablearrangement that satisfies sections 6.2.1, 6.2.2, and 6.2.3 isacceptable.6.2.1 Instrument Stab
32、ilityThe 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 time period of 3 days shall be#20J/s per gram sample per hour
33、 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. The long term drift is then the slope inthe line J/g/s/h an
34、d 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) (4).6.2.2 Instrument SensitivityThe minimum sensitivity formeasuring power output shall be 100 J/s.6.2.3 Isothermal ConditionsThe instrument shall mai
35、n-tain the temperature of the sample to within1Kofthethermostated temperature.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. The data acqui-sition equipment shall be capable of performin
36、g 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 the sample islow. Some data acquisition equipment is designe
37、d 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 quality as integrated signalamplifiers.7. Instrument Calibration7
38、.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 instrument shall be capable of providing datadescribed in 7
39、.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 schematically in Fig. 2.7.1.1 Mount the resistance heater an
40、d 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 sample per hour).7.1.1.2 Re
41、cord 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 of some hardware, it ma
42、y not be zero.FIG. 2 (A) Schematic Steady-State Calibration Using A 2-Point Calibration Process And (B) Multi-Point Calibration ProcessC1702 09a37.1.2 Power in the heater circuit is related to voltage andresistance by the following equation:P 5 I2R (1)where:P = power, J/s,I = applied current, ampere
43、s, andR = resistance, ohms.Apply sufficient voltage to the heater circuit to generate a heatoutput of approximately 0.1 J/s, measured to an accuracy of5%.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 V1for a power P1
44、(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 about 0.02 J/s/g. The alit
45、e 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 Calibration CoeffcientsCalcula
46、te 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 units of mV, is the ind
47、ependent 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, as in the following eq
48、uation: 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 several calo-rimeters, all channels shall be calibrated individually. How-ever, it is possible to calibrate all calor
49、imeters simultaneouslyusing multiple resistance heaters and having the same currentpassing through the heaters in all calorimeter cells.7.1.5 Calibration shall be executed at regular intervals todetermine the calibration coefficient. The length of the timeintervals between calibrations is dependent on the instrumentand the personnel, and must be determined empirically. If thecalibration coefficient differs more than 2 % from one calibra-tion to the next, then calibrations intervals must be reduceduntil this stability limit is reached.8. Proced
