1、Designation: D 3752 98 (Reapproved 2006)Standard Test Method forStrength Imparted by Asbestos to a Cementitious Matrix1This standard is issued under the fixed designation D 3752; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、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 measurement, on a labora-tory scale, of the contribution of asbestos fibers to th
3、e strengthof asbestos-cement products. The results obtained are used inthe primary assessment of different fiber grades prior to theirapplication on a larger scale.1.2 This test method covers the determination of the modu-lus of rupture (MR), adjusted to a dry density of 1.60Mg/m3(MRA), of asbestos-
4、cement test specimens that containthe asbestos fiber to be evaluated at a concentration of 10mass %, whereby the degree of fiberization of that fiber isspecified in terms of specific surface area as determined byTestMethod D 2752. The relative reinforcing value of the fiberunder test is established
5、by comparison with MRAvaluesobtained with a fiber of known characteristics at a fiberconcentration of 10 % and a dry density of 1.60 Mg/m3(1.60g/cm3).NOTE 1The adjusted modulus of rupture (MRA) at any intermediatefiber concentration may be interpolated from results suitably determinedover a limited
6、spanning range of fiber concentrations. For example, theMRAat 10 % fiber concentration may be graphically determined from dataat 3 and 17 %.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 WarningBreathing of asbestos du
7、st is hazardous.Asbestos and asbestos products present demonstrated healthrisks for users and for those with whom they come into contact.In addition to other precautions, when working with asbestos-cement products, minimize the dust that results. For informa-tion on the safe use of chrysotile asbest
8、os, refer to “Safe Use ofChrysotile: A Manual on Preventive and Control Measures.”21.5 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 establish appro-priate safety and health practices and
9、determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C 150 Specification for Portland CementC 184 Test Method for Fineness of Hydraulic Cement bythe 150-m (No. 100) and 75-m (No. 200) Sieves4C 204 Test Methods for Fineness of Hydraulic Cement
10、 byAir-Permeability ApparatusD 1193 Specification for Reagent WaterD 2589 Test Method for McNett Wet Classification of DualAsbestos FiberD 2590 Test Method for Sampling Chrysotile AsbestosD 2752 Test Methods for Air Permeability of AsbestosFibersD 2946 Terminology for Asbestos and AsbestosCementProd
11、uctsD 3879 Test Method for Sampling Amphibole AsbestosE 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods2.2 Other Standard:5Quebec Asbestos Mining Association (QAMA) StandardDesignation for Chrysotile Asbestos Grades3. Terminology3.1 DefinitionsFor definitions of asbestos ter
12、ms used inthis test method, refer to Terminology D 2946.4. Summary of Test Method4.1 This test method covers the preparation and flexuraltesting of asbestos-cement specimens consisting of disks, 107mm in diameter, which are obtained by vacuum filtration of anaqueous slurry of asbestos fiber, cement,
13、 and silica of standardcomposition. The disks are compressed to a designated nomi-nal pressure (Note 2), and cured under standard conditionsprior to testing in flexure. The calculation of the modulus ofrupture (MR) and its adjustment to a common dry density of1.6 Mg/m3(MRA), based on the flexural st
14、rength and thedensity of the specimens, is also described.1This test method is under the jurisdiction of ASTM Committee C17 onFiber-Reinforced Cement Products and is the direct responsibility of SubcommitteeC17.03 on Asbestos-Cement Sheet Products and Accessories.Current edition approved June 1, 200
15、6. Published June 2006. Originallyapproved in 1979. Last previous edition approved in 2002 as D 3752 98 (2002)e1.2Available from The Asbestos Institute, http:/ referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM
16、Standards volume information, refer to the standards Document Summary page onthe ASTM website.4Withdrawn.5Available from the Asbestos Institute, 1002 Sherbrooke St. W, Suite 1750,Montreal, QC, Canada H3A 3L6.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 194
17、28-2959, United States.NOTE 2The spacer ring may support part or all of this pressure unlessthe mix being pressed is bulky enough to prevent full closure of the mold.4.2 The preparation of the test specimens and the determi-nation of the flexural modulus of rupture includes the followingsteps:4.2.1
18、Treatment of the asbestos fiber including sampling,blending, and fiberizing in a suitable apparatus,4.2.2 Dry blending of asbestos fiber, cement, and silica andthe wet mixing of these materials using water saturated withlime and gypsum.4.2.3 Formation of disk-shaped filter cakes from the aque-ous sl
19、urry in a cylindrical filter vessel and the pressing of thosecakes,4.2.4 Curing of the pressed cakes by storage under condi-tions of high humidity and autoclaving,4.2.5 Determination of the volume and density of thespecimens based on dry mass, saturated mass, and immersedmass,4.2.6 Testing of the fl
20、exural strength of the cured specimensafter drying, and4.2.7 Calculation of the flexural modulus of rutpure (MR)ofthe specimens and the modulus of rupture adjusted to a drydensity of 1.6 Mg/m3(MRA).5. Significance and Use5.1 This procedure facilitates the comparison of differenttypes or grades of as
21、bestos based on their contribution to theflexural modulus of rupture; that is, the reinforcing value,which is considered the most pertinent property for themanufacture of asbestos-cement products.5.2 This test method is primarily intended for fiber gradesused normally in asbestos-cement products (Gr
22、oup 6 to Group4 fibers). Longer fibers (Group 3) or shorter fibers (Group 7)may present difficulties during the preparation of the filter cakebecause of poor dispersion and uneven settling.66. Apparatus6.1 FiberizingOptimum fiberization in terms of reinforc-ing strength (based on measurement of spec
23、ific surface area (asdetermined by Test Method D 2752) varies with the type ofasbestos fiber; for example, approximately 900 m2/kg foramosite, 1200 to 1500 m2/kg for crocidolite and 1000 to 1800m2/kg for chrysotile. It should be noted that optimum fiberiza-tion based on filtration properties may req
24、uire different surfaceareas. It should also be noted that optimum fiberization interms of reinforcing strength varies with the fiberizing proce-dure. To produce the desired degree of fiberization, thefollowing types of apparatus have been found suitable:6.1.1 Laboratory Fan Opener.6.1.2 Pallman Mill
25、.6.1.3 Christie-Norris Mill.NOTE 3The choice of the fiberizing method and the degree offiberization is dependent upon the type of fiber under test, the applicationfor which the fiber is intended, and the specific purpose of the testprogram. Increasingly higher surface areas obtained by fiberizationp
26、roduce increasingly higher modulus of rupture values up to an observedoptimum. Beyond that point, due to the production of greater proportionsof fines coinciding with increasingly higher surface areas, modulus ofrupture values may diminish.6.2 Dry and Wet Mixing:6.2.1 Wide-Mouth Plastic Containers,
27、100 mm in diameter,200 mm high, with screw lid.6.2.2 Metal Mixing Rod, 10 mm in diameter, 250 mm long,with a disk fixed to its end, leaving 5-mm clearance to the innerwall of the plastic container (Fig. 1).6.2.3 Spare Screw Lids, with 10-mm hole in center toreceive stem of mixing rod.NOTE 4A Patters
28、on-Kelly mixer with a one litre capacity shell hasalso been found to be suitable for dry and wet mixing, using mixing timesof 5 min each.6.3 Forming of the of the Specimens:6.3.1 Vacuum Filtering System (Fig. 2):6.3.1.1 Vacuum Pump, capable of displacing 180 L/min andcapable of attaining 9.5 kPa (71
29、0 mm Hg).6.3.1.2 Vacuum Gage Assembly, consisting of one 10 kPa (0to 750-mm Hg) vacuum gage, needle valves, or a vacuumcontroller.76The term “Group 3, 4, 5, 6, or 7” refers to the Standard Designation forChrysotile Asbestos Grades by the Quebec Asbestos Mining Association (QAMA).7An Edwards Model 1A
30、 has been found suitable. If you are aware of alternativesuppliers, please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.FIG. 1 Plastic Mixing Vessel and Mixing Rod
31、D 3752 98 (2006)26.3.1.3 Filter Funnel, Hartly-type, three-piece Bchner fun-nel, 107 mm in diameter.6.3.1.4 Filter Papers, 100 mm in diameter, hardened andfast filtering, or filter cloth.6.3.2 Spatula, stainless steel, narrow blade, approximately150 mm long.6.3.3 Stopwatch.NOTE 5Test specimens of 10
32、0 to 150 mm may be prepared and testedby this test method, in which case appropriate changes should be made inthe quantities of materials used and the size of the equipment, such asmold and filter paper.6.4 Pressing of Specimens:6.4.1 Hydraulic Press, capable of exerting 200 kN load.6.4.2 Mold Assem
33、bly (Fig. 3)The thickness, t,isintheorder of 6 mm.6.4.3 Plastic Squares, 130 mm wide by 3 mm thick.NOTE 6Although a spacer ring as shown in Fig. 3 is used to controlthe thickness of the specimen (see Note 2) and to obtain a dry density ofapproximately 1.6 Mg/m3, an adjustment by calculation (see 13.
34、4)toadrydensity of exactly 1.6 Mg/m3, although small, is still required.6.5 Curing of Specimens:6.5.1 Humidity Cabinet, designed for 90 % relative humid-ity at 20C.86.5.2 Laboratory Autoclave, capable of maintaining a satu-rated steam pressure of 834 to 1079 kPa for 16 h and with acapacity of approx
35、imately 100 L.9If an autoclave is notavailable, the disks can be water-cured (see 11.3).6.5.3 Drying Oven, standard mechanical or gravity-convection oven, capable of maintaining 1056 2C and withan internal capacity of approximately 0.2 m3.6.6 Testing of Specimens:6.6.1 Laboratory Balance, capable of
36、 weighing 0.6 kg to100 mg.106.6.2 Flexural Tester, capable of applying 600 g to 100 mg11accuracy for a transverse load up to 2.5 kN to the center of aspan of 82.6-mm with a steady crosshead speed of 5 mm/min.The loading bar and supports should be 25-mm diameter steelrods.6.6.3 Micrometer, approximat
37、ely 50-mm throat, 0.02-mmgraduations.6.6.4 Graduated Cylinder, 500-cm3capacity.7. Reagents and Materials7.1 Portland Cement, Type 1 in accordance with Specifica-tion C 150, or equivalent, with a Blaine surface area of 340 620 m2/kg as determined by Test Method C 204, and pulverizedsilica passing the
38、 180 m (No. 80) sieve but retained on the 75m (No. 200) sieve as determined by Test Method C 184, witha Blaine surface area of 300 6 20 m2/kg as determined by TestMethod C 204 shall be used when the test results are intendedfor comparisons between laboratories. Other portland cementsand silica may b
39、e used for in-house laboratory comparisons.Small amounts of these materials should be dried to constantweight at 100C, mixed thoroughly, and stored separately inairtight containers. (Blaine surface area determinations areobtained by Test Method C 204.)7.2 Water Saturated with Lime and Gypsum WaterAd
40、d 2g each of calcium sulfate dihydrate (CaSO42H2O) and calciumhydroxide Ca(OH)2(reagent grade) to 1 dm3ofType IVreagentwater as defined by Specification D 1193 at 20C. Stir thewater mechanically or by shaking for 2 min, and after settlingof the undissolved solids for 24 h, siphon the solution intoan
41、other container for storage without exposure to air.(WarningSee 1.4.)8A Harshaw No. H-18877 stainless steel desiccating cabinet has been foundsatisfactory for this purpose. If you are aware of alternative suppliers, please providethis information to ASTM International Headquarters. Your comments wil
42、l receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.9A Cenco laboratory autoclave Model 126X has been found suitable. If you areaware of alternative suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will
43、receive careful consideration at a meetingof the responsible technical committee,1which you may attend.10A Mettler top-loading balance Model P-1200N with a capacity of 1.0 kg anda 0.2-kg tare, has been found suitable. If you are aware of alternative suppliers,please provide this information to ASTM
44、International Headquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.11A 250-g proving ring with a Carver press has been found suitable.FIG. 2 Vacuum Filter systemD 3752 98 (2006)38. Sampling8.1 Chrysotile FiberSample
45、each chrysotile fiber in ac-cordance with Test Method D 2590.8.2 Amphibole FibersSample amphibole fibers in accor-dance with Test Method D 3879.9. Fiber Treatment (Opening)9.1 FiberizingIf the surface area of the asbestos fiber tobe tested is below those mentioned in 6.1, a fiberizing step maybe req
46、uired prior to testing.Avariety of methods (see 6.1) havebeen found suitable for fiberizing or opening asbestos fiber.During the fiberizing process, the surface area of the asbestosfiber is increased and, depending upon the method and lengthof treatment used, the abestos fiber is generally shortened
47、.Therefore, it is recommended that in addition to the treatmentmethod and the surface area, the fiber length, as determined byTest Method D 2589, be recorded prior to and after thefiberizing treatment.10. Specimen Preparation10.1 Dry and Wet MixingWeigh asbestos fiber, portlandcement, and silica acc
48、urately to the nearest 0.1 g in theappropriate proportions to obtain a combined weight of 0.100kg. (For a fiber concentration of 10 %, prepare 0.010 kg offiber, 0.054 kg of cement, and 0.036 kg of silica.) Place fiber,cement, and silica into the plastic container, seal and shake for1 min, holding th
49、e container horizontally and using horizontalmotions. Add 400 cm3of water saturated with lime andgypsum, and mix for 1 min using the mixing rod with 30 rapidvertical strokes. (Care should be taken not to entrain air into theslurry.)10.2 Forming of SpecimenPrior to the transfer of theslurry to the Bchner funnel, adjust the vacuum to 53 kPa (400mm Hg) with the stopcock between the funnel and vacuumsource in the closed position. Then pour the mixed slurry intothe three-piece Bchner funnel containing a wetted fi
