1、Designation: C70 13 American Association StateHighway and Transportation Officials StandardAASHTO No.: T142Standard Test Method forSurface Moisture in Fine Aggregate1This standard is issued under the fixed designation C70; the number immediately following the designation indicates the year of origin
2、aladoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defen
3、se.1. Scope1.1 This test method covers field determination of theamount of surface moisture in fine aggregate by displacementin water.1.2 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 esta
4、blish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.3 The values stated in SI units are to be regarded as thestandard. No other units of measurement are included in thisstandard.2. Referenced Documents2.1 ASTM Standards:2C128 Test
5、Method for Density, Relative Density (SpecificGravity), and Absorption of Fine AggregateC566 Test Method for Total Evaporable Moisture Content ofAggregate by DryingC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Materials3. Significance and Use3.1 This test
6、 method is not widely used. However, it is aconvenient procedure for field or plant determination ofmoisture content of fine aggregate if specific gravity values areknown and if drying facilities are not available. It can be usedto adjust the aggregate mass for moisture content and todetermine surfa
7、ce moisture contribution to mixing water inportland cement concrete.3.2 The accuracy of the test method depends upon accurateinformation on the bulk specific gravity of the material in asaturated surface-dry condition.4. Apparatus4.1 Balance, having a capacity of 2 kg or more and sensitiveto 0.5 g o
8、r less.4.2 FlaskA suitable container or flask, preferably of glassor noncorrosive metal. The container may be a pycnometer, avolumetric flask, a graduated volumetric flask, or other suitablemeasuring device. The volume of the container shall be fromtwo to three times the loose volume of the sample.
9、Thecontainer shall be so designed that it can be filled to the mark,or the volume of its contents read, within 0.5 mL or less.5. Sample5.1 Select a representative sample of the fine aggregate to betested for surface moisture content. It shall weigh not less than200 g. Larger samples will yield more
10、accurate results.6. Procedure6.1 The surface water content may be determined either bymass or volume. In each case the test shall be made at atemperature range of 18 to 29C.6.2 Determination by MassDetermine the mass of thecontainer, in grams, filled to the mark with only water. Beforeplacing the sa
11、mple into the container, adjust the level of thewater so that it will be sufficient to cover the sample withoutgoing over the original mark. Introduce the weighed sample offine aggregate into the container and remove the entrapped air.Fill the container to the original mark, and determine the massin
12、 grams. Calculate the amount of water displaced by thesample, as follows:Md5 Mc1Ms2 M (1)where:Md= mass of water displaced by the sample, g,Mc= mass of container filled to the mark with water, g,Ms= mass of sample, g, andM = mass of container and sample, filled to the mark withwater, g.1This test me
13、thod is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregatesand is the direct responsibility of SubcommitteeC09.20 on Normal Weight Aggregates.Current edition approved Feb. 1, 2013. Published February 2013. Originallyapproved in 1970. Last previous edition approved in 2006
14、 as C70 06. DOI:10.1520/C0070-13.2For 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 Document Summary page onthe ASTM website.Copyright ASTM International
15、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.3 Determination by VolumeMeasure a volume of water,in millilitres, sufficient to cover the sample and place in thecontainer. Introduce the weighed sample of fine aggregate intothe container and remove the entrapp
16、ed air. Determine thecombined volume of the sample and the water by direct readingwhen a graduated flask is used. When a pycnometer orvolumetric flask of known volume is used, fill the container tothe known volume mark with an additional measured volumeof water. The flask or pycnometer volume is the
17、n equal to thecombined volume of sample and water. Calculate the amountof water displaced by the sample, as follows:Vs5 V22 V1(2)where:Vs= volume of water displaced by the sample, mL,V2= combined volume of sample and water, mL, andV1= total volume of water in the flask or pycnometerrequired to cover
18、 the sample and bring the level up tothe known volume mark, mL.7. Calculation7.1 Calculate the percentage of surface moisture in terms ofthe saturated surface-dry fine aggregate (see Appendix X1), asfollows:P 5 Md2 Vd!/Ms2 Md!# 3100 (3)where:P = surface moisture in terms of saturated surface-dry fin
19、eaggregate, %,Vd= mass of the sample (Msin 6.2) divided by the bulkspecific gravity of the fine aggregate in a saturatedsurface-dry condition, determined as prescribed in TestMethod C128, andMd= mass of water displaced, g, andMs= mass of sample, g7.2 Calculate the percentage of surface moisture in t
20、erms ofdry aggregate if the absorption of the aggregate is known asfollows:Pd5 P11Pa/100!#(4)where:Pd= surface moisture in terms of dry fine aggregate, %, andPa= absorption of the fine aggregate, %, determined inaccordance with Test Method C128.Total moisture content, on a dry aggregate basis, is th
21、e sumof the surface moisture, Pd, and the absorption, Pa.8. Report8.1 Report surface moisture test results as determined bythis method to the nearest 0.1 %.9. Precision and Bias9.1 This procedure is estimated to be less precise thanproperly conducted moisture content tests by drying (TestMethod C566
22、). Accurate specific gravity information is essen-tial to the bias of this method. Test Method C566 can be usedto verify the level of bias.9.2 PrecisionThese estimates of precision are based onresults from the AASHTO Materials Reference Laboratory(AMRL) Proficiency Sample Program, of testing conduct
23、ed onFine Aggregate Proficiency Sample Numbers 99 and 100. Theprecision limits are based on test results submitted by 144laboratories that tested two fine aggregate test samples ofapproximately 500 g mass with average surface moisturecontents of 2.323 % and 2.075 % respectively.9.2.1 Single-Operator
24、 PrecisionThe single-operator stan-dard deviation of a single test result has been found to be0.50 %.3Therefore, results of two properly conducted tests bythe same operator should not differ by more than 1.39 %.9.2.2 Multilaboratory PrecisionThe multilaboratory stan-dard deviation of a single test r
25、esult has been found to be0.82 %.3Therefore, results of two properly conducted tests indifferent laboratories on the same material should not differ bymore than 2.31 %.39.3 BiasSince there is no accepted reference materialsuitable for determining the bias of this test procedure, nostatement on bias
26、(other than that in 9.1) is made.10. Keywords10.1 fine aggregate; fine aggregate moisture; surface mois-tureAPPENDIX(Nonmandatory Information)X1. DEVELOPMENT OF EQUATIONSX1.1 These equations are readily derived from basic rela-tionships. For convenience express P in terms of the ratio r,that is, the
27、 ratio of the mass of surface moisture to the mass ofthe saturated, surface-dry sample. It follows that:r 5Ms2 Ms/11r!#Ms/11r!(X1.1)X1.1.1 If G is bulk specific gravity of the saturated, surface-dry fine aggregate, thenMd5MsG11r!1Ms2Ms11r(X1.2)where the first term gives the water displaced by thesat
28、urated surface-dry fine aggregate and the second that dis-placed by the surface moisture.3These numbers represent, respectively, the (1s) and d2s) limits as described inPractice C670.C70132X1.1.2 From Eq X1.2:Ms11r5Md2 Ms1G2 1(X1.3)By definition,Ms5 VdG (X1.4)X1.1.3 Substituting for Ms/(1 + r) and M
29、sin Eq X1.1 andsimplifying,r 5 Md2 Vd!/Ms2 Md! (X1.5)ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent ri
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