1、Designation: C1608 12C1608 17Standard 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.
2、 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 measures the internal (absolute) volume change of hydraulic cement paste that results from the hydrationof the cem
3、entitious materials. This volume change is known 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 the standard.1.3 This standard does not purport to address all of the safety concerns, if any, ass
4、ociated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. (WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin andtis
5、sue upon prolonged exposure.2)1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organiz
6、ation Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C114 Test Methods for Chemical Analysis of Hydraulic CementC186 Test Method for Heat of Hydration of Hydraulic CementC188 Test Method for Density of Hydraulic CementC219 Terminology Relating to Hydraulic Cem
7、entC305 Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic ConsistencyC511 Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of HydraulicCements and ConcretesC670 Practice for Preparing Precision and Bias Statements
8、 for Test Methods for Construction Materials3. Terminology3.1 Definitions:3.1.1 chemical shrinkage, nthe absolute (internal) volume change accompanying the hydration of cement, due to the fact thatthe cement hydration products occupy less physical volume than the reactants.3.1.2 All other terms are
9、as defined in Terminology C219.4. Significance and Use4.1 Numerous properties of cementitious materials are controlled by their initial hydration rate. Examples include early-agestrength development, heat release, and crack resistance. One direct and convenient measure of this initial hydration rate
10、 isprovided by the measurement of the chemical shrinkage of the cement paste during its hydration.As cement hydrates, the hydrationproducts occupy less volume than the initial reacting materials (cement and water). Due to this volume change, a hydrating cementpaste will sorb water from its immediate
11、 surroundings, when available. At early times, this sorption is in direct proportion to the1 This test method is under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.31 on Volume Change.Current edition approved Oct. 15, 2012Aug. 1, 2017. Publish
12、ed November 2012August 2017. Originally approved in 2005. Last previous edition approved in 20072012as C1608 07.C1608 12. DOI: 10.1520/C1608-12.10.1520/C1608-17.2 See the section on Safety, Manual of Cement Testing, Annual Book of ASTM Standards, Vol. 04.01.3 For referencedASTM standards, visit theA
13、STM website, www.astm.org, or 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 i
14、ndication of what changes have 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 b
15、e considered the official document.*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 States1amount of hydration that has occurred.4 This method is based on the one developed by G
16、eiker.5 The results are relevant tounderstanding the hydration behavior of cements. This method does not measure the bulk volume changes (autogenous shrinkage)associated with chemical shrinkage nor the cracking potential of concretes produced with the evaluated cement.5. Apparatus5.1 Devices for Det
17、ermining Mass, conforming to the requirements of Method Test Methods C114 and evaluated for precisionand accuracy at a total load of 100 g.5.2 Constant Temperature Water Batha water bath capable of maintaining a temperature of 23.0 6 0.5 C, 0.5C, with asufficient capacity to hold the specimens being
18、 evaluated. To avoid evaporative cooling, the surface of the water in the bath shallbe covered with floating plastic balls or fitted with an insulated lid.5.3 Timing DeviceClock that can measure time to the nearest minute.5.4 For procedureProcedure A5.4.1 Capillary TubeA graduated glass capillary tu
19、be with graduations of 0.01 mL or smaller, and typically a capacity of 1.0mL.5.4.2 Small Glass Vials (e.g., (for example, 22-mm diameter and 55-mm height) with Rubber Stoppers that fit tightly into theglass vials and have a hole placed in each stopper with the graduated capillary tube inserted throu
20、gh the hole (as shown in Fig.1). Fix the capillary tube in the stopper using a two-component epoxy or other suitable adhesive applied at the stoppers top andbottom surfaces.5.5 For Procedure B5.5.1 Density bottle, glass, capacity approximately 20 mlmL with internally conical glass stopper as shown i
21、n Fig. 2.6. Reagents and Materials6.1 Paraffin oil.6.2 De-aerated water (prepared by boiling water and sealing it in a closed container before it has cooled.)4 L.J. Parrott, M. Geiker, W.A. Gutteridge, and D. Killoh, “Monitoring Portland Cement Hydration: Comparison of Methods,” Cement and Concrete
22、Research, Vol. 20,919-926, 1990.5 M. Geiker, “Studies of Portland Cement Hydration: Measurements of Chemical Shrinkage and a Systematic Evaluation of Hydration Curves by Means of the DispersionModel,” Ph.D. Thesis, Technical University of Denmark, Copenhagen, Denmark, 1983.FIG. 1 Illustration of One
23、 Experimental Setup for Monitoring Chemical Shrinkage of Hydrating Cement Paste Using Procedure A.C1608 1727. Procedure7.1 Preparation of Cement PastePrepare the cement paste in accordance with the proportions and procedure described in TestMethod C186 (Note 1). The pastes shall be prepared in a mix
24、ing room meeting the temperature and humidity requirements outlinedin Specification C511. Record to the nearest minute the time when the water first contacts the dry cement powder.NOTE 1Other mixing procedures such as mixing in a Hobart mixer (see Practice C305) or kneading by hand in a sealed plast
25、ic bag may be used.The standard paste mixture uses 150 g of cement and 60 mlmL of water (water-cement ratio of 0.40). Adjust the volume of paste mixed to match themixing equipment used. Other water-cement ratios may be used as long as they are stated in the test report; higher water-cement ratios ma
26、y producesignificant bleeding of the cement paste which will influence the results (by changing the effective water-cement ratio, etc.); and so forth); lowerwater-cement ratios may lead to difficulties in preparing a fully compacted, homogeneous paste for subsequent evaluation and self-desiccation m
27、ay occur.7.2 Prepare a minimum of two replicate specimens as described below for either Procedure A or Procedure B.7.3 Procedure A7.3.1 Determine the mass of each empty glass vial to the nearest 0.01 g.7.3.2 Carefully place the prepared cement paste into the glass vial to achieve a paste height betw
28、een 5 mm and 10 mm in thevial (Note 2). Consolidate the paste in the vial by tapping the vial on a laboratory countertop, or placing it on a vibrating table,or some similar procedure.NOTE 2For applications requiring a water-cement ratio or water-cementitious material ratio of less than 0.40, it is r
29、ecommended that the paste heightbe reduced to 3 mm or less. Thicker samples can experience a process called depercolation, resulting in the measured chemical shrinkage being less thanthe true value.5,67.3.3 Determine the mass of each glass vial with the cement paste to the nearest 0.01 g.7.3.4 Caref
30、ully, without disturbing the cement paste, add clean, de-aerated water to fill the glass vial to the top.7.3.5 Place the rubber stopper with the inserted capillary tube tightly into the glass vial. Be careful to avoid the entrapment ofair bubbles when the bottom rubber stopper surface encounters the
31、 water in the glass vial. As the rubber stopper is inserted, thewater level in the graduated capillary tube will rise. Optimally, the water level should rise near to but not beyond the top mark ofthe graduations on the capillary tube. If the water level is not near enough to the top mark, clean, de-
32、aerated water can be addedvia the top of the capillary tube to achieve the desired initial water height. Once the rubber stopper has been fitted to the vial, thecompleted assembly shall be handled only by the vial (not by the capillary tube) to avoid loosening of the rubber stopper whichwill result
33、in an apparent volume change of the specimen.7.3.6 Place a drop of paraffin oil in the top of the graduated capillary tube to minimize water evaporation from the tube duringthe 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
34、prepared specimens in the constant temperature water bath at 23 C 23C such that the tops of the glass vialsare just above the water level in the bath. Maintain the temperature of the laboratory at 23 6 2 C. 2C. Record the time and initiallevel (height) of water, to the nearest 0.0025 mL, in the capi
35、llary tubes.7.3.9 Periodically (every 30 min or every hour, as convenient) record the time to the nearest minute and water level in thecapillary tubes to the nearest 0.0025 mL for a total period of at least 24 h. After the first 8 h, the recording intervals can belengthened to 8 h or more to avoid t
36、aking readings during the night, as long as a 24 h reading is obtained the following day. Besure to take a reading 1 h after the paste was first mixed to use as a zero point in all calculations (this allows time for the specimento achieve temperature equilibrium within the water bath).7.3.10 At the
37、termination of the measurements, dry off the exterior of the vial and determine the final mass of the assembledvial/capillary tube to the nearest 0.01 g. If the difference between the initial and final masses for a given replicate is greater than0.02 g, that specimens chemical shrinkage data shall b
38、e discarded.7.4 Procedure B7.4.1 Determine the mass of each empty density bottle to the nearest 0.0001 g.7.4.2 Carefully place the prepared cement paste into the density bottle to achieve a paste height between 5 mm and 10 mm10 mm in the bottle. Consolidate the paste in the bottle by tapping the bot
39、tle on a laboratory countertop, or placing it on a vibratingtable or some similar procedure. Determine the mass of the density bottle with the consolidated cement paste to the nearest 0.0001g.7.4.3 Carefully, without disturbing the cement paste, add clean, de-aerated water to fill the bottle to the
40、top.7.4.4 Place the stopper tightly into the bottle. Be careful to remove any entrapped air bubbles when the bottom of the stopperencounters the water in the bottle. Add clean, de-aerated water via the perforated stopper to fill the bottle and stopper to excess(leave a bead of water on the top of th
41、e stopper to overfill the capillary tube). The filled assembly shall be handled only by thebottle (not by the stopper) to avoid loosening the stopper, which will result in an apparent change in the specimen, and not withbare fingers (e.g., (for example, wear latex gloves) which will cause an increas
42、e in mass due to transfer of oil.6 Sant, G., Bentz, D., and Weiss, J., “Capillary porosity depercolation in cement-based materials: Measurement techniques and factors which influence their interpretation,”Cement and Concrete Research, 41(8), 854-864, 2011.C1608 1737.4.5 Remove the excess water from
43、the top of the stopper using absorbent paper, wiping quickly to avoid sucking water outof the capillary tube.7.4.6 Immediately determine the mass of the density bottle filled with water to the top of the capillary tube. Determine the massto the nearest 0.0001 g.7.4.7 Place the filled density bottles
44、 in the constant temperature water bath at 23 C 23C such that the tops of the stoppers arejust above the water level in the bath.7.4.8 At 1 h after the paste was first mixed, remove the density bottle from the water bath and wipe dry, fill to excess with water,remove the excess and determine the mas
45、s to the nearest 0.0001 g.7.4.9 Periodically (every 30 or 60 min, as convenient) for a period of at least 24 h, 24 h, remove the density bottle from thewater bath and wipe dry, fill to excess with water, remove the excess and determine the mass to the nearest 0.0001 g. After thefirst eight hours, th
46、e recording intervals can be lengthened to 8 h or more to avoid taking readings during the night, as long as a24 h 24 h reading is obtained the following day.8. Calculation8.1 The chemical shrinkage is computed as the measured mL of sorbed water per gram of cement in the paste specimen. Themass of c
47、ement powder in the vial is given by:Mcement5Mvial1paste2Mvialempty!S1.01wc D(1)whereMcement = mass of cement in the vial (g),Mvial+paste = mass of the glass vial with the added cement paste (g),Mvialempty = mass of the empty vial (g), andw/c = water-cement ratio by mass of the prepared paste (e.g.,
48、 0.40) and a density of 1000 kg/m3 is assumed for water.w/c = water-cement ratio by mass of the prepared paste (for example, 0.40) and a density of 1000 kgm3 is assumed forwater.8.2 Procedure A8.2.1 The chemical shrinkage per unit mass of cement at time t is computed as:CSt! 5ht!2h60min!#Mcement(2)w
49、hereCS(t) = chemical shrinkage at time t (mL/g cement) (Note 3).h(t) = water level in capillary tube at time t (mL)CS(t) = chemical shrinkage at time t (mL/g cement) (Note 3), andh(t) = water level in capillary tube at time t (mL).NOTE 3If it is desired to report the chemical shrinkage per unit volume of cement powder, the values from Eq 2 and Eq 3 can be converted to mL/mLcement using the density of the cement powder determined using Test Method C188.8.3 Procedure B8.3.1 The chemical shrinkage per unit mass of cement at time t is computed as:CSt! 5S
