1、Designation:D375298 (Reapproved 2006) Designation: D3752 98 (Reapproved 2011)Standard Test Method forStrength Imparted by Asbestos to a Cementitious Matrix1This standard is issued under the fixed designation D3752; the number immediately following the designation indicates the year oforiginal adopti
2、on 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 measurement, on a laboratory scale, of the con
3、tribution of asbestos fibers to the strength ofasbestos-cement products. The results obtained are used in the primary assessment of different fiber grades prior to their applicationon a larger scale.1.2 This test method covers the determination of the modulus of rupture (MR), adjusted to a dry densi
4、ty of 1.60 Mg/m3(MRA),of asbestos-cement test specimens that contain the asbestos fiber to be evaluated at a concentration of 10 mass %, whereby thedegree of fiberization of that fiber is specified in terms of specific surface area as determined by Test Method D2752. The relativereinforcing value of
5、 the fiber under test is established by comparison with MRAvalues obtained with a fiber of knowncharacteristics at a fiber concentration of 10 % and a dry density of 1.60 Mg/m3(1.60 g/cm3).NOTE 1The adjusted modulus of rupture (MRA) at any intermediate fiber concentration may be interpolated from re
6、sults suitably determined overa limited spanning range of fiber concentrations. For example, the MRAat 10 % fiber concentration may be graphically determined from data at 3 and17 %.1.3The values stated in SI units are to be regarded as the standard. The values given in parentheses are for informatio
7、n only.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 WarningBreathing of asbestos dust is hazardous. Asbestos and asbestos products present demonstrated health risks forusers and for those with whom they come into co
8、ntact. In addition to other precautions, when working with asbestos-cementproducts, minimize the dust that results. For information on the safe use of chrysotile asbestos, refer to “Safe Use of Chrysotile:A Manual on Preventive and Control Measures.”21.5 This standard does not purport to address all
9、 of the safety concerns, if any, associated 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.2. Referenced Documents2.1 ASTM Standards:3C150 Specification for
10、Portland CementC184 Test Method for Fineness of Hydraulic Cement by the 150-m (No. 100) and 75-m (No. 200) SievesC204 Test Methods for Fineness of Hydraulic Cement by Air-Permeability ApparatusD1193 Specification for Reagent WaterD2589 Test Method for McNett Wet Classification of Dual Asbestos Fiber
11、D2590 Test Method for Sampling Chrysotile AsbestosD2752 Test Methods for Air Permeability of Asbestos FibersD2946 Terminology for Asbestos and AsbestosCement ProductsD3879 Test Method for Sampling Amphibole AsbestosE177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods2.2 Other S
12、tandard:4Quebec Asbestos Mining Association (QAMA) Standard Designation for Chrysotile Asbestos Grades1This test method is under the jurisdiction of ASTM Committee C17 on Fiber-Reinforced Cement Products and is the direct responsibility of Subcommittee C17.03 onAsbestos - Cement Sheet Products and A
13、ccessories.Current edition approved June 1, 2006. Published June 2006. Originally approved in 1979. Last previous edition approved in 2002 as D375298 (2002)1. DOI:10.1520/D3752-98R06.Current edition approved Nov. 1, 2011. Published February 2012. Originally approved in 1979. Last previous edition ap
14、proved in 2006 as D3752 98 (2006). DOI:10.1520/D3752-98R11.2Available from The Asbestos Institute, http:/ referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards
15、Document Summary page on the ASTM website.4Available from the Asbestos Institute, 1002 Sherbrooke St. W, Suite 1750, Montreal, QC, Canada H3A 3L6.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the pr
16、evious 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 be considered the official document.Copyright ASTM
17、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 DefinitionsFor definitions of asbestos terms used in this test method, refer to Terminology D2946.4. Summary of Test Method4.1 This test method covers the preparation and flexural tes
18、ting of asbestos-cement specimens consisting of disks, 107 mm indiameter, which are obtained by vacuum filtration of an aqueous slurry of asbestos fiber, cement, and silica of standardcomposition. The disks are compressed to a designated nominal pressure (Note 2), and cured under standard conditions
19、 prior totesting in flexure. The calculation of the modulus of rupture ( MR) and its adjustment to a common dry density of 1.6 Mg/m3(MRA), based on the flexural strength and the density of the specimens, is also described.NOTE 2The spacer ring may support part or all of this pressure unless the mix
20、being pressed is bulky enough to prevent full closure of the mold.4.2 The preparation of the test specimens and the determination of the flexural modulus of rupture includes the following steps:4.2.1 Treatment of the asbestos fiber including sampling, blending, and fiberizing in a suitable apparatus
21、,4.2.2 Dry blending of asbestos fiber, cement, and silica and the wet mixing of these materials using water saturated with limeand gypsum.4.2.3 Formation of disk-shaped filter cakes from the aqueous slurry in a cylindrical filter vessel and the pressing of those cakes,4.2.4 Curing of the pressed cak
22、es by storage under conditions of high humidity and autoclaving,4.2.5 Determination of the volume and density of the specimens based on dry mass, saturated mass, and immersed mass,4.2.6 Testing of the flexural strength of the cured specimens after drying, and4.2.7 Calculation of the flexural modulus
23、 of rutpure (MR) of the specimens and the modulus of rupture adjusted to a dry densityof 1.6 Mg/m3(MRA).5. Significance and Use5.1 This procedure facilitates the comparison of different types or grades of asbestos based on their contribution to the flexuralmodulus of rupture; that is, the reinforcin
24、g value, which is considered the most pertinent property for the manufacture ofasbestos-cement products.5.2 This test method is primarily intended for fiber grades used normally in asbestos-cement products (Group 6 to Group 4fibers). Longer fibers (Group 3) or shorter fibers (Group 7) may present di
25、fficulties during the preparation of the filter cake becauseof poor dispersion and uneven settling.56. Apparatus6.1 FiberizingOptimum fiberization in terms of reinforcing strength (based on measurement of specific surface area (asdetermined by Test Method D2752) varies with the type of asbestos fibe
26、r; for example, approximately 900 m2/kg for amosite, 1200to 1500 m2/kg for crocidolite and 1000 to 1800 m2/kg for chrysotile. It should be noted that optimum fiberization based on filtrationproperties may require different surface areas. It should also be noted that optimum fiberization in terms of
27、reinforcing strengthvaries with the fiberizing procedure. To produce the desired degree of fiberization, the following types of apparatus have beenfound suitable:6.1.1 Laboratory Fan Opener.6.1.2 Pallman Mill.6.1.3 Christie-Norris Mill.NOTE 3The choice of the fiberizing method and the degree of fibe
28、rization is dependent upon the type of fiber under test, the application for whichthe fiber is intended, and the specific purpose of the test program. Increasingly higher surface areas obtained by fiberization produce increasingly highermodulus of rupture values up to an observed optimum. Beyond tha
29、t point, due to the production of greater proportions of fines coinciding withincreasingly higher surface areas, modulus of rupture values may diminish.6.2 Dry and Wet Mixing:6.2.1 Wide-Mouth Plastic Containers, 100 mm in diameter, 200 mm high, with screw lid.6.2.2 Metal Mixing Rod, 10 mm in diamete
30、r, 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 to receive stem of mixing rod.NOTE 4A Patterson-Kelly mixer with a one litre capacity shell has also been found to be suitable for
31、 dry and wet mixing, using mixing times of 5min 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 and capable of attaining 9.5 kPa (710 mm Hg).5The term “Group 3, 4, 5, 6, or 7” refers to the Standard Designation for
32、Chrysotile Asbestos Grades by the Quebec Asbestos Mining Association (QAMA).D3752 98 (2011)26.3.1.2 Vacuum Gage Assembly, consisting of one 10 kPa (0 to 750-mm Hg) vacuum gage, needle valves, or a vacuumcontroller.66.3.1.3 Filter Funnel, Hartly-type , three-piece Bchner funnel, 107 mm in diameter.6.
33、3.1.4 Filter Papers, 100 mm in diameter, hardened and fast filtering, or filter cloth.6.3.2 Spatula, stainless steel, narrow blade, approximately 150 mm long.6.3.3 Stopwatch.NOTE 5Test specimens of 100 to 150 mm may be prepared and tested by this test method, in which case appropriate changes should
34、 be made in thequantities of materials used and the size of the equipment, such as mold and filter paper.6An Edwards Model 1A has been found suitable. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Yourcomments will receive careful cons
35、ideration at a meeting of the responsible technical committee, which you may attend.FIG. 1 Plastic Mixing Vessel and Mixing RodFIG. 2 Vacuum Filter systemD3752 98 (2011)36.4 Pressing of Specimens:6.4.1 Hydraulic Press, capable of exerting 200 kN load.6.4.2 Mold Assembly (Fig. 3)The thickness, t, is
36、in the order 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 control the thickness of the specimen (see Note 2) and to obtain a dry density ofapproximately 1.6 Mg/m3, an adjustment by calculation (see 13.4) to a dry density of exact
37、ly 1.6 Mg/m3, although small, is still required.6.5 Curing of Specimens:6.5.1 Humidity Cabinet, designed for 90 % relative humidity at 20C.76.5.2 Laboratory Autoclave, capable of maintaining a saturated steam pressure of 834 to 1079 kPa for 16 h and with a capacityof approximately 100 L.8If an autoc
38、lave is not available, 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 with an internalcapacity of approximately 0.2 m3.6.6 Testing of Specimens:6.6.1 Laboratory Balance, capable of weighing 0.6 kg to 100 m
39、g.96.6.2 Flexural Tester, capable of applying 600 g to 100 mg10accuracy for a transverse load up to 2.5 kN to the center of a spanof 82.6-mm with a steady crosshead speed of 5 mm/min. The loading bar and supports should be 25-mm diameter steel rods.6.6.3 Micrometer, approximately 50-mm throat, 0.02-
40、mm graduations.6.6.4 Graduated Cylinder, 500-cm3capacity.7. Reagents and Materials7.1 Portland Cement, Type 1 in accordance with Specification C150, or equivalent, with a Blaine surface area of 340 6 20m2/kg as determined by Test Method C204, and pulverized silica passing the 180 m (No. 80) sieve bu
41、t retained on the 75 m(No. 200) sieve as determined by Test Method C184, with a Blaine surface area of 300 6 20 m2/kg as determined by Test MethodC204 shall be used when the test results are intended for comparisons between laboratories. Other portland cements and silica maybe used for in-house labo
42、ratory comparisons. Small amounts of these materials should be dried to constant weight at 100C, mixedthoroughly, and stored separately in airtight containers. (Blaine surface area determinations are obtained by Test Method C204.)7.2 Water Saturated with Lime and Gypsum WaterAdd 2 g each of calcium
43、sulfate dihydrate (CaSO42H2O) and calciumhydroxide Ca(OH)2(reagent grade) to 1 dm3of Type IV reagent water as defined by Specification D1193 at 20C. Stir the watermechanically or by shaking for 2 min, and after settling of the undissolved solids for 24 h, siphon the solution into anothercontainer fo
44、r storage without exposure to air. (WarningSee 1.4.)7A Harshaw No. H-18877 stainless steel desiccating cabinet has been found satisfactory for this purpose. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receive carefu
45、l consideration at a meeting of the responsible technical committee, which you mayattend.8A Cenco laboratory autoclave Model 126X has been found suitable. If you are aware of alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful
46、consideration at a meeting of the responsible technical committee, which you may attend.9AMettler top-loading balance Model P-1200N with a capacity of 1.0 kg and a 0.2-kg tare, has been found suitable. If you are aware of alternative suppliers, please providethis information to ASTM International He
47、adquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you mayattend.10A 250-g proving ring with a Carver press has been found suitable.NOTE 1t can be adjusted to give a density of 1.6 g/cm3.FIG. 3 Press MoldD3752 98 (2011)48. Sampling
48、8.1 Chrysotile FiberSample each chrysotile fiber in accordance with Test Method D2590.8.2 Amphibole FibersSample amphibole fibers in accordance with Test Method D3879.9. Fiber Treatment (Opening)9.1 FiberizingIf the surface area of the asbestos fiber to be tested is below those mentioned in 6.1, a f
49、iberizing step may berequired prior to testing. A variety of methods (see 6.1) have been found suitable for fiberizing or opening asbestos fiber. Duringthe fiberizing process, the surface area of the asbestos fiber is increased and, depending upon the method and length of treatmentused, the abestos fiber is generally shortened. Therefore, it is recommended that in addition to the treatment method and the surfacearea, the fiber length, as determined by Test Method D2589, be recorded prior to and after the fib
