ASTM C1608-2012 Standard Test Method for Chemical Shrinkage of Hydraulic Cement Paste《水凝水泥浆化学收缩的标准试验方法》.pdf

《ASTM C1608-2012 Standard Test Method for Chemical Shrinkage of Hydraulic Cement Paste《水凝水泥浆化学收缩的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM C1608-2012 Standard Test Method for Chemical Shrinkage of Hydraulic Cement Paste《水凝水泥浆化学收缩的标准试验方法》.pdf（5页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: C1608 12Standard Test Method forChemical Shrinkage of Hydraulic Cement Paste1This standard is issued under the fixed designation C1608; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numbe

2、r 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 measures the internal (absolute) vol-ume change of hydraulic cement paste that results from thehydration of the cementitio

3、us materials. This volume change isknown as chemical shrinkage.1.1.1 Procedure A, volumetric method.1.1.2 Procedure B, the density method.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated wi

4、th its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon

5、 prolonged exposure.2)2. Referenced Documents2.1 ASTM Standards:3C114 Test Methods for Chemical Analysis of HydraulicCementC186 Test Method for Heat of Hydration of HydraulicCementC188 Test Method for Density of Hydraulic CementC219 Terminology Relating to Hydraulic CementC305 Practice for Mechanica

6、l Mixing of Hydraulic CementPastes and Mortars of Plastic ConsistencyC511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Constructio

7、n Materials3. Terminology3.1 Definitions:3.1.1 chemical shrinkage, nthe absolute (internal) vol-ume change accompanying the hydration of cement, due to thefact that the cement hydration products occupy less physicalvolume than the reactants.3.1.2 All other terms are as defined in Terminology C219.4.

8、 Significance and UseNumerous properties of cementitious materials are controlledby their initial hydration rate. Examples include early-agestrength development, heat release, and crack resistance. Onedirect and convenient measure of this initial hydration rate isprovided by the measurement of the c

9、hemical shrinkage ofthe cement paste during its hydration. As cement hydrates,the hydration products occupy less volume than the initialreacting materials (cement and water). Due to this volumechange, a hydrating cement paste will sorb water from itsimmediate surroundings, when available. At early t

10、imes, thissorption is in direct proportion to the amount of hydrationthat has occurred.4This method is based on the one devel-oped by Geiker.5The results are relevant to understandingthe hydration behavior of cements. This method does notmeasure the bulk volume changes (autogenous shrinkage)associat

11、ed with chemical shrinkage nor the cracking poten-tial of concretes produced with the evaluated cement.5. Apparatus5.1 Devices for Determining Mass, conforming to the re-quirements of Method C114 and evaluated for precision andaccuracy at a total load of 100 g.5.2 Constant Temperature Water Batha wa

12、ter bath ca-pable of maintaining a temperature of 23.0 6 0.5 C, with asufficient capacity to hold the specimens being evaluated. Toavoid evaporative cooling, the surface of the water in the bathshall be covered with floating plastic balls or fitted with aninsulated lid.1This test method is under the

13、 jurisdiction of ASTM Committee C01 on Cementand is the direct responsibility of Subcommittee C01.31 on Volume Change.Current edition approved Oct. 15, 2012. Published November 2012. Originallyapproved in 2005. Last previous edition approved in 2007 as C1608 07. DOI:10.1520/C1608-12.2See the section

14、 on Safety, Manual of Cement Testing, Annual Book of ASTMStandards, Vol. 04.01.3For 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 Document Summary page o

15、nthe ASTM website.4L.J. Parrott, M. Geiker, W.A. Gutteridge, and D. Killoh, “Monitoring PortlandCement Hydration: Comparison of Methods,” Cement and Concrete Research, Vol.20, 919-926, 1990.5M. Geiker, “Studies of Portland Cement Hydration: Measurements of ChemicalShrinkage and a Systematic Evaluati

16、on of Hydration Curves by Means of theDispersion Model,” Ph.D. Thesis, Technical University of Denmark, Copenhagen,Denmark, 1983.*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

17、 States15.3 Timing DeviceClock that can measure time to thenearest minute.5.4 For procedure A5.4.1 Capillary TubeA graduated glass capillary tube withgraduations of 0.01 mL or smaller, and typically a capacity of1.0 mL.5.4.2 Small Glass Vials (e.g., 22-mm diameter and 55-mmheight) with Rubber Stoppe

18、rs that fit tightly into the glass vialsand have a hole placed in each stopper with the graduatedcapillary tube inserted through the hole (as shown in Fig. 1).Fix the capillary tube in the stopper using a two-componentepoxy or other suitable adhesive applied at the stoppers topand bottom surfaces.5.

19、5 For Procedure B5.5.1 Density bottle, glass, capacity approximately 20 mlwith internally conical glass stopper as shown in Fig. 2.6. Reagents and Materials6.1 Paraffin oil.6.2 De-aerated water (prepared by boiling water and sealingit in a closed container before it has cooled.)7. Procedure7.1 Prepa

20、ration of Cement PastePrepare the cement pastein accordance with the proportions and procedure described inTest Method C186 (Note 1). The pastes shall be prepared in amixing room meeting the temperature and humidity require-ments outlined in Specification C511. Record to the nearestminute the time w

21、hen the water first contacts the dry cementpowder.NOTE 1Other mixing procedures such as mixing in a Hobart mixer(see Practice C305) or kneading by hand in a sealed plastic bag may beused. The standard paste mixture uses 150 g of cement and 60 ml of water(water-cement ratio of 0.40). Adjust the volum

22、e of paste mixed to matchthe mixing equipment used. Other water-cement ratios may be used aslong as they are stated in the test report; higher water-cement ratios mayproduce significant bleeding of the cement paste which will influence theresults (by changing the effective water-cement ratio, etc.);

23、 lower water-cement ratios may lead to difficulties in preparing a fully compacted,homogeneous paste for subsequent evaluation and self-desiccation mayoccur.7.2 Prepare a minimum of two replicate specimens asdescribed below for either Procedure A or Procedure B.7.3 Procedure A7.3.1 Determine the mas

24、s of each empty glass vial to thenearest 0.01 g.7.3.2 Carefully place the prepared cement paste into theglass vial to achieve a paste height between 5 mm and 10 mmin the vial (Note 2). Consolidate the paste in the vial by tappingthe vial on a laboratory countertop, or placing it on a vibratingtable,

25、 or some similar procedure.NOTE 2For applications requiring a water-cement ratio or water-cementitious material ratio of less than 0.40, it is recommended that thepaste height be reduced to 3 mm or less. Thicker samples can experiencea process called depercolation, resulting in the measured chemical

26、shrinkage being less than the true value.5,67.3.3 Determine the mass of each glass vial with the cementpaste to the nearest 0.01 g.6Sant, G., Bentz, D., and Weiss, J., “Capillary porosity depercolation incement-based materials: Measurement techniques and factors which influence theirinterpretation,”

27、 Cement and Concrete Research, 41(8), 854-864, 2011.FIG. 1 Illustration of One Experimental Setup for Monitoring Chemical Shrinkage of Hydrating Cement Paste Using Procedure A.C1608 1227.3.4 Carefully, without disturbing the cement paste, addclean, de-aerated water to fill the glass vial to the top.

28、7.3.5 Place the rubber stopper with the inserted capillarytube tightly into the glass vial. Be careful to avoid theentrapment of air bubbles when the bottom rubber stoppersurface encounters the water in the glass vial. As the rubberstopper is inserted, the water level in the graduated capillarytube

29、will rise. Optimally, the water level should rise near to butnot beyond the top mark of the graduations on the capillarytube. If the water level is not near enough to the top mark,clean, de-aerated water can be added via the top of the capillarytube to achieve the desired initial water height. Once

30、the rubberstopper has been fitted to the vial, the completed assembly shallbe handled only by the vial (not by the capillary tube) to avoidloosening of the rubber stopper which will result in an apparentvolume change of the specimen.7.3.6 Place a drop of paraffin oil in the top of the graduatedcapil

31、lary tube to minimize water evaporation from the tubeduring the testing period.7.3.7 Determine the initial mass of the assembled vial/capillary tube to the nearest 0.01 g.7.3.8 Place the prepared specimens in the constant tempera-ture water bath at 23 C such that the tops of the glass vials arejust

32、above the water level in the bath. Maintain the temperatureof the laboratory at 23 6 2 C. Record the time and initial level(height) of water, to the nearest 0.0025 mL, in the capillarytubes.7.3.9 Periodically (every 30 min or every hour, as conve-nient) record the time to the nearest minute and wate

33、r level inthe capillary tubes to the nearest 0.0025 mL for a total periodof at least 24 h. After the first 8 h, the recording intervals canbe lengthened to8hormore to avoid taking readings duringthe night, as long as a 24 h reading is obtained the followingday. Be sure to take a reading 1 h after th

34、e paste was first mixedto use as a zero point in all calculations (this allows time for thespecimen to achieve temperature equilibrium within the waterbath).7.3.10 At the termination of the measurements, dry off theexterior of the vial and determine the final mass of theassembled vial/capillary tube

35、 to the nearest 0.01 g. If thedifference between the initial and final masses for a givenreplicate is greater than 0.02 g, that specimens chemicalshrinkage data shall be discarded.7.4 Procedure B7.4.1 Determine the mass of each empty density bottle to thenearest 0.0001 g.7.4.2 Carefully place the pr

36、epared cement paste into thedensity bottle to achieve a paste height between 5 mm and 10mm in the bottle. Consolidate the paste in the bottle by tappingthe bottle on a laboratory countertop, or placing it on avibrating table or some similar procedure. Determine the massof the density bottle with the

37、 consolidated cement paste to thenearest 0.0001 g.7.4.3 Carefully, without disturbing the cement paste, addclean, de-aerated water to fill the bottle to the top.7.4.4 Place the stopper tightly into the bottle. Be careful toremove any entrapped air bubbles when the bottom of thestopper encounters the

38、 water in the bottle. Add clean, de-aerated water via the perforated stopper to fill the bottle andstopper to excess (leave a bead of water on the top of thestopper to overfill the capillary tube). The filled assembly shallbe handled only by the bottle (not by the stopper) to avoidloosening the stop

39、per, which will result in an apparent changein the specimen, and not with bare fingers (e.g., wear latexgloves) which will cause an increase in mass due to transfer ofoil.7.4.5 Remove the excess water from the top of the stopperusing absorbent paper, wiping quickly to avoid sucking waterout of the c

40、apillary tube.7.4.6 Immediately determine the mass of the density bottlefilled with water to the top of the capillary tube. Determine themass to the nearest 0.0001 g.7.4.7 Place the filled density bottles in the constant tempera-ture water bath at 23 C such that the tops of the stoppers arejust abov

41、e the water level in the bath.7.4.8 At 1 h after the paste was first mixed, remove thedensity bottle from the water bath and wipe dry, fill to excesswith water, remove the excess and determine the mass to thenearest 0.0001 g.7.4.9 Periodically (every 30 or 60 min, as convenient) for aperiod of at le

42、ast 24 h, remove the density bottle from the waterbath and wipe dry, fill to excess with water, remove the excessand determine the mass to the nearest 0.0001 g. After the firsteight hours, the recording intervals can be lengthened to8hormore to avoid taking readings during the night, as long as a 24

43、h reading is obtained the following day.8. Calculation8.1 The chemical shrinkage is computed as the measuredmL of sorbed water per gram of cement in the paste specimen.The mass of cement powder in the vial is given by:Mcement5Mvial1paste2 Mvialempty!S1.01wcD(1)whereMcement= mass of cement in the via

44、l (g),Mvial+paste= mass of the glass vial with the added cementpaste (g),Mvialempty= mass of the empty vial (g),FIG. 2 Illustration of a Density Bottle for Use in Procedure B.C1608 123w/c = water-cement ratio by mass of the preparedpaste (e.g., 0.40) and a density of 1000 kg/m3isassumed for water.8.

45、2 Procedure A8.2.1 The chemical shrinkage per unit mass of cement attime t is computed as:CSt! 5ht! 2 h60min!#Mcement(2)whereCS(t) = chemical shrinkage at time t (mL/g cement) (Note3).h(t) = water level in capillary tube at time t (mL)NOTE 3If it is desired to report the chemical shrinkage per unitv

46、olume of cement powder, the values from Eq 2 can be converted tomL/mL cement using the density of the cement powder determined usingTest Method C188.8.3 Procedure B8.3.1 The chemical shrinkage per unit mass of cement attime t is computed as:CSt! 5SMt! 2 M60min!#McementD/W (3)where:CS(t) = chemical s

47、hrinkage at time t (mL/g cement)M(t) = mass of filled density bottle at time t (g)W = density of water (mL/g) (0.99754 at 23 C)9. Report9.1 Report the following:9.1.1 Date and time paste specimen is prepared;9.1.2 Cementitious material sources and names;9.1.3 Mixing and compaction procedure employed

48、 andwater-cement ratio by mass;9.1.4 Mass of each empty vial and mass of each vial withcement paste;9.1.5 A table of the water level in each capillary tube or themass of each filled density bottle vs. time;9.1.6 Atable and/or plot of the chemical shrinkage per gramof cement (reported to the nearest

49、0.0001 mL/g) vs. time.10. Precision and Bias10.1 PrecisionThe precision statements for this testmethod are listed in Table 1 and are based on the resultsobtained in an interlaboratory study described in ResearchReport C01-10107(Note 4).10.2 BiasSince there is no accepted reference materialsuitable for determining the bias of this procedure, no state-ment on bias is made.NOTE 4The interlaboratory study included 7 laboratories and 1portland cement (CCRL 152). The average volume change was -0.0266mL/g.11. Keywords11.1 chemical shrinkage; hydration.SUMMAR