1、Designation: C 1702 09Standard Test Method forMeasurement of Heat of Hydration of HydraulicCementitious Materials Using Isothermal ConductionCalorimetry1This standard is issued under the fixed designation C 1702; 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. Scope1.1 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 C 1679.1.3 The values stated in SI u
4、nits 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 pr
5、actices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 186 Test Method for Heat of Hydration of HydraulicCementC 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC 1679 Practice fo
6、r Measuring 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
7、 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 measures heat flow from a sample maintained at a constanttemperature by intimate thermal cont
8、act 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
9、-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 random noise (standard deviation) in thebaseline signal.3.1.6 thermal power, nthe heat produc
10、tion 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
11、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 conductivity. One heat-flow sensorand sample holder contains the sample of interest. The otherheat-flow sensor is a re
12、ference 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. Th
13、e heat-flow sensor actually senses a smalltemperature gradient 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 electr
14、icalvoltage 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 by measurements1This test method is under the jurisdiction of ASTM Committee C01 on Cementand is the direct responsibility of Subco
15、mmittee C01.26 on Heat of Hydration.Current edition approved July 1, 2009. Published August 2009.2For 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 Docum
16、ent Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.on 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
17、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 Method B the sample is mixed outside ofthe calorimeter then put into the calorimeter. This methodoffers cer
18、tain practicality, but depending on the materials beinganalyzed and procedures used for mixing and handling, thismethod may suffer from small errors due to periods ofhydration being missed or spurious heat being introduced ortaken away from the calorimeter during setup or combinationsthereof. Method
19、s of correction are offered for these potentialerrors.5. Significance and Use5.1 This method is suitable for determining the total heat ofhydration of hydraulic cement at constant temperature at agesup to 7 days to confirm specification compliance. It gives testresults equivalent to Test Method C 18
20、6 up to 7 days of age(Poole (2007) (4).5.2 This method compliments Practice C 1679 by providingdetails of calorimeter equipment, calibration, and operation.Practice C 1679 emphasizes interpretation significant events incement hydration by analysis of time dependent patterns ofheat flow, but does not
21、 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.6.1.2 Volumetric DispenserA device for measuring vol-ume or mass of water, accurate to 0.1 mL. This
22、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 mixing water. If usingcommercially manufactured equipment, consult the recom-mendations of the manuf
23、acturer 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 constant-voltage power supply such that a stable output of 0.010 60.0002 J/s can be generated (see N
24、ote 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 plaster of Parisembedded with a small resistor. Plaster of Paris has only a transient heatof hydration an
25、d 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 from aninert material with similar heat capacity and shape as the testsample. This is used in the re
26、ference 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 calorimeter does not contain built-in calibration capability.6.1.7 Power SupplyA constant voltage DC powe
27、r 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 calibration capability.NOTE 2A power output of at least 0.33 J/s is needed for mostapplications.6.1.8 Insulat
28、ed ContainerUsed in the Method B de-scribed in 8.3.5.1. This device can be fabricated using a 500mL (approximate volume) container insulated 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 m
29、easuringtemperature changes to the nearest 0.1 C and of a physicalconfiguration that allows it to operate in the confines of theinsulated 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
30、 specimens, each thermally connected to heatflow 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 satisf
31、ies sections 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 propertyFIG. 1 Schematic Drawing of a Heat Conduction CalorimeterC1702092shall be verified on a new instrument and whenever there arequesti
32、ons 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 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 t
33、o 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 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) (4).6.2.2 Inst
34、rument SensitivityThe minimum sensitivity formeasuring power output shall be 100 J/s.6.2.3 Isothermal ConditionsThe instrument shall main-tain the temperature of the sample to within1Kofthethermostated temperature.6.3 Data Acquisition EquipmentData acquisition equip-ment may be built into the calori
35、meter instrument package, orit may be an off-the-shelf, stand-alone, item. The 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 flexi
36、bility to adjust the readinginterval to longer times when power output from the 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 %, o
37、r comparable capabilities to condi-tion the power output into the same quality as integrated signalamplifiers.7. Instrument Calibration7.1 Instrument CalibrationCommercially manufacturedinstruments designed for measuring heat of hydration ofcementitious materials may have instrument specific calibra
38、-tion procedures. Conform to these procedures if they exist. Inaddition, the 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 proc
39、edure.Calibration shall be at least a two-point process. This isillustrated schematically in Fig. 2.7.1.1 Mount 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 he
40、at 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 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 refer
41、ence cell usually resultsin the V0being a relatively small number but, depending on the variabilityin properties 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 ProcessC17020937.1.2 Power in the he
42、ater circuit is related to voltage andresistance by the following equation:P 5 I2R (1)where:P = power, J/s,I = applied current, amperes, 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 Allo
43、w 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(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 r
44、ange of the calorimeter.NOTE 5The early C3A reaction of a typical portland cement evolvesa maximum power of about 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. A 5 g sample then generates power peaks in the range of 0.10J
45、/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 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),
46、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 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 eq
47、uation is found to be suitable in manyinstruments over the operating range necessary to analyze portlandcements, 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 inst
48、rument containing several calo-rimeters, all channels shall be calibrated individually. How-ever, it is possible to calibrate all calorimeters simultaneouslyusing multiple resistance heaters and having the same currentpassing through the heaters in all calorimeter cells.7.1.5 Calibration shall be ex
49、ecuted 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. Procedure8.1 Turn on the calorimeter equipment and data acquisitionunit. Determine that the calorimeter is at temperature equilib-rium by verifying that the baseline is stabl
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