1、Designation: C 948 81 (Reapproved 2001)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 C 948; the number immediately following the designation indicates the
2、 year 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determinations of dry
3、andwet 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 dr
4、ying 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 of thespecimen and on
5、the 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 pr
6、essure 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 This
7、 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 practices and determine the applica-bility of regulatory limitations prior to use.2. Significance and Use
8、2.1 Material properties determined by this test method areuseful for quality control of 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 determinin
9、g the mass of the specimen inwater as well as in air.3.2 Container, suitable for immersing the specimen andsuitable wire for suspending the specimen in water.4. Sampling4.1 Sampling method shall be in accordance with govern-ing specifications.5. Test Specimen5.1 Whenever possible, the sample shall c
10、onsist of indi-vidual portions of glass-fiber reinforced concrete, each to betested separately. 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.
11、7 oz, and shall not begreater than 650 cm3or 1300 g nominal glass-fiber reinforcedconcrete, 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
12、water at approximately 21C(70F) for not less than 24 h and until two successivedeterminations 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 (0.0003
13、4 oz). Designatethis mass as A.NOTE 2Take care during this operation to ensure that air bubbles 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
14、the nearest0.01 g. Designate this saturated surface-dry mass as B.6.2 Oven-Dry MassDry the specimen in an oven at atemperature of 100 to 110C (212 to 230F) for not less than 24h and until two successive determinations of mass of the driedspecimen at intervals of 2 h show a decrease in mass of lessth
15、an 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 to1This test method is under the jurisdiction of ASTM Committee C27 on PrecastConcrete Products and is the direct respons
16、ibility of Subcommittee C27.40 on GlassFiber Reinforced Concrete Made by the Spray-Up Process.Current edition approved June 8, 1981. Published August 1981.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the nearest 0.01 g (0.00034 oz
17、). Designate this mass as C.7. Calculation7.1 Using the masses determined in accordance with theprocedures described in Section l6, make the calculations asfollows (Note 3):Dry bulk density, g/cm35CB A(1)Wet bulk density, g/cm35BB A(2)Water absorption, % 5B CCx 100 (3)Apparent porosity, % 5B CB Ax 1
18、00 (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, theden
19、sity 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
20、.4.2 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
21、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 rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revis
22、ion 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 c
23、omments 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 copyrig
24、hted 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).C 9482
