1、Designation: C948 81 (Reapproved 2016)Standard Test Method forDry and Wet Bulk Density, Water Absorption, and ApparentPorosity of Thin Sections of Glass-Fiber ReinforcedConcrete1This standard is issued under the fixed designation C948; the number immediately following the designation indicates the y
2、ear oforiginal adoption 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 covers the determinations of dry and
3、wet bulk density, water absorption, and apparent porosity ofthin sections of glass-fiber reinforced concrete.NOTE 1This test method does not involve a determination of absolutespecific gravity. Therefore, such pore space as may be present in thespecimen that is not emptied during the specified dryin
4、g or is not filledwith water during the specified immersion is considered “impermeable”and is not differentiated from the solid portion of the specimen for thecalculations, especially those for percent voids.Depending upon the pore size distribution and the pore entry radii ofthe specimen and on the
5、 purposes for which the test results are desired, theprocedures of this method may be adequate, or they may be insufficientlyrigorous. In the event that it is desired to fill more of the pores than willbe filled by immersion, various techniques involving the use of vacuumtreatment or increased press
6、ure may be used. If a rigorous measure of totalpore space is desired, this can only be obtained by determining absolutespecific gravity by first reducing the sample to discrete particles, each ofwhich is sufficiently small so that no impermeable space can exist withinany of the particles.1.2 The val
7、ues stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with
8、 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.2. Significance and Use2.1 Material properties determined by this test method areuseful for quality control of
9、glass-fiber reinforced concrete,ascertaining compliance with governing specifications, andresearch and development.3. Apparatus3.1 Balance, sensitive to 0.025 % of the mass of thespecimen, suitable for determining the mass of the specimen inwater as well as in air.3.2 Container, suitable for immersi
10、ng the specimen andsuitable wire for suspending the specimen in water.4. Sampling4.1 Sampling method shall be in accordance with governingspecifications.5. Test Specimen5.1 Whenever possible, the sample shall consist of indi-vidual portions of glass-fiber reinforced concrete, each to betested separa
11、tely. The individual portions may be pieces of anydesired shape or size, except that the volume of each portionshall be not less than 25 cm3(or 50 g nominal mass glass-fiberreinforced concrete, approximately 1.7 oz, and shall not begreater than 650 cm3or 1300 g nominal glass-fiber reinforcedconcrete
12、, approximately 46 oz); and each portion shall be freeof observable cracks, fissures, or shattered edges.6. Procedure6.1 Immersed Mass and Saturated SurfaceDry Mass AfterImmersion:6.1.1 Immerse the specimen in water at approximately 21C(70F) for not less than 24 h and until two successivedeterminati
13、ons of mass of the surface-dried specimens atintervals of 2 h show an increase in mass of less than 0.5 % ofthe heavier mass. Determine the mass of the specimen sus-pended in water to the nearest 0.01 g (0.00034 oz). Designatethis mass as A.NOTE 2Take care during this operation to ensure that air bu
14、bbles donot adhere to the surface of the specimen.6.1.2 Remove the specimen from the water and quicklysurface dry the specimen by removing surface moisture with atowel. Immediately determine the mass in air to the nearest0.01 g. Designate this saturated surface-dry mass as B.6.2 Oven-Dry MassDry the
15、 specimen in an oven at atemperature of 100 to 110C (212 to 230F) for not less than 241This test method is under the jurisdiction of ASTM Committee C27 on PrecastConcrete Products and is the direct responsibility of Subcommittee C27.40 on GlassFiber Reinforced Concrete.Current edition approved April
16、 1, 2016. Published May 2016. Originallyapproved in 1981. Last previous edition approved in 2009 as C948 81(2009). DOI:10.1520/C0948-81R16.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1h and until two successive determinations of ma
17、ss of the driedspecimen at intervals of 2 h show a decrease in mass of lessthan 0.5 % of the lowest mass obtained. After removing thespecimen from the oven, allow it to cool in dry air (preferablyin a desiccator) to room temperature and determine its mass tothe nearest 0.01 g (0.00034 oz). Designate
18、 this mass as C.7. Calculation7.1 Using the masses determined in accordance with theprocedures described in Section 6, make the calculations asfollows (Note 3):Dry bulk density, g/cm35CB 2 A(1)Wet bulk density, g/cm35BB 2 A(2)Water absorption, % 5B 2 CC3 100 (3)Apparent porosity, % 5B 2 CB 2 A3 100
19、(4)where:A = immersed mass, g,B = saturated-surface-dry mass, g, andC = oven-dry mass, g.NOTE 3Assuming the specific gravity of water to be 1 g/cm3, thedifference in the weight of a saturated sample weighed in air and in wateris equal to the apparent volume of the sample in cm3. Therefore, thedensit
20、y determination calculations have the units of g/cm3.8. Report8.1 The report shall include the following:8.1.1 Identification number of specimen,8.1.2 Sample description and specimen size,8.1.3 Date of testing, and8.1.4 Test results:8.1.4.1 Dry bulk density to the nearest 0.01 g/cm3(1 lb/ft3),8.1.4.
21、2 Wet bulk density to the nearest 0.01 g/cm3(1 lb/ft3),8.1.4.3 Water absorption to the nearest 0.1 %, and8.1.4.4 Apparent porosity to the nearest 0.1 %.9. Precision and Bias9.1 The precision and bias criteria are being developed.ASTM International takes no position respecting the validity of any pat
22、ent 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 rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision
23、 at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comm
24、ents will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighte
25、d by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 81 (2016)2
