1、Standard Method of Test for Specific Gravity and Absorption of Fine Aggregate AASHTO Designation: T 84-131ASTM Designation: C128-12 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1c T 84-1 AASHTO Standard Method o
2、f Test for Specific Gravity and Absorption of Fine Aggregate AASHTO Designation: T 84-131ASTM Designation: C128-12 1. SCOPE 1.1. This method covers the determination of bulk and apparent specific gravity, 23/23C (73.4/73.4F), and absorption of fine aggregate. 1.2. This method determines (after 1519
3、h of soaking in water) the bulk specific gravity and the apparent specific gravity, the bulk specific gravity on the basis of mass of saturated surface-dry aggregate, and the absorption. 1.3. The values stated in SI units are to be regarded as the standard. 1.4. This standard may involve hazardous m
4、aterials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory lim
5、itations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 6, Fine Aggregate for Hydraulic Cement Concrete M 231, Weighing Devices Used in the Testing of Materials T 2, Sampling of Aggregates T 11, Materials Finer Than 75-m (No. 200) Sieve in Mineral Aggregates by Washing T 19M/T 19, Bu
6、lk Density (“Unit Weight”) and Voids in Aggregate T 85, Specific Gravity and Absorption of Coarse Aggregate T 100, Specific Gravity of Soils T 133, Density of Hydraulic Cement T 248, Reducing Samples of Aggregate to Testing Size T 255, Total Evaporable Moisture Content of Aggregate by Drying 2.2. AS
7、TM Standard: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 84-2 AASHTO 2.3. IEEE/
8、ASTM Standard: SI10, American National Standard for Metric Practice 3. TERMINOLOGY 3.1. Definitions: 3.1.1. absorptionthe increase in the mass of aggregate due to water in the pores of the material, but not including water adhering to the outside surface of the particles, expressed as a percentage o
9、f the dry mass. The aggregate is considered “dry” when it has been maintained at a temperature of 110 5C for sufficient time to remove all uncombined water by reaching a constant mass. 3.1.2. specific gravitythe ratio of the mass (or weight in air) of a unit volume of a material to the mass of the s
10、ame volume of gas-free distilled water at stated temperatures. Values are dimensionless. 3.1.2.1. apparent specific gravitythe ratio of the weight in air of a unit volume of the impermeable portion of aggregate at a stated temperature to the weight in air of an equal volume of gas-free distilled wat
11、er at a stated temperature. 3.1.2.2. bulk specific gravitythe ratio of the weight in air of a unit volume of aggregate (including the permeable and impermeable voids in the particles, but not including the voids between particles) at a stated temperature to the weight in air of an equal volume of ga
12、s-free distilled water at a stated temperature. 3.1.2.3. bulk specific gravity (SSD)the ratio of the mass in air of a unit volume of aggregate, including the mass of water within the voids filled to the extent achieved by submerging in water for 1519 h (but not including the voids between particles)
13、 at a stated temperature, compared to the weight in air of an equal volume of gas-free distilled water at a stated temperature. 4. SIGNIFICANCE AND USE 4.1. Bulk specific gravity is the characteristic generally used for calculation of the volume occupied by the aggregate in various mixtures containi
14、ng aggregate including portland cement concrete, bituminous concrete, and other mixtures that are proportioned or analyzed on an absolute volume basis. Bulk specific gravity is also used in the computation of voids in aggregate in T 19M/T 19. Bulk specific gravity determined on the saturated surface
15、-dry basis is used if the aggregate is wet; that is, if its absorption has been satisfied. Conversely, the bulk specific gravity determined on the oven-dry basis is used for computations when the aggregate is dry or assumed to be dry. 4.2. Apparent specific gravity pertains to the relative density o
16、f the solid material making up the constituent particles not including the pore space within the particles that is accessible to water. This value is not widely used in construction aggregate technology. 4.3. Absorption values are used to calculate the change in the mass of an aggregate due to water
17、 absorbed in the pore spaces within the constituent particles, compared to the dry condition, when it is deemed that the aggregate has been in contact with water long enough to satisfy most of the absorption potential. The laboratory standard for absorption is that obtained after soaking dry aggrega
18、te in water. Aggregates mined from below the water table may have a higher absorption when used, if not allowed to dry. Conversely, some aggregates when used may contain an amount of absorbed moisture less than that achieved by the required amount of soaking time: For an aggregate that has been in c
19、ontact with water and that has free moisture on the particle surfaces, 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 84-3 AASHTO the percentage of free moisture can be determined by deducting t
20、he absorption from the total moisture content determined by T 255 by drying. 5. APPARATUS 5.1. Balance, conforming to the requirements of M 231, Class G 2. 5.2. PycnometerA flask or other suitable container into which the fine aggregate test sample can be readily introduced and in which the volume c
21、ontent can be reproduced with 100 mm3. The volume of the container filled to mark shall be at least 50 percent greater than the space required to accommodate the test sample. A volumetric flask of 500-mL capacity or a fruit jar fitted with a pycnometer top is satisfactory for a 500-g test sample of
22、most fine aggregates. A Le Chatelier flask as described in T 133 is satisfactory for an approximately 55-g test sample. 5.3. MoldA metal mold in the form of a frustum of a cone with dimensions as follows: 40 3 mm inside diameter at the top, 90 3 mm inside diameter at the bottom, and 75 3 mm in heigh
23、t, with the metal having a minimum thickness of 0.8 mm. 5.4. TamperA metal tamper having a mass of 340 15 g and having a flat circular tamping face 25 3 mm in diameter. 6. SAMPLING 6.1. Sampling shall be accomplished in general accordance with T 2. 7. PREPARATION OF TEST SPECIMEN 7.1. Obtain approxi
24、mately 1 kg of the fine aggregate from the sample using the applicable procedures described in T 248. 7.1.1. Dry it in a suitable pan or vessel to constant mass at a temperature of 110 5C (230 9F). Allow it to cool to comfortable handling temperature, cover with water, either by immersion or by the
25、addition of at least 6 percent moisture to the fine aggregate and permit to stand for 15 to 19 h. 7.1.2. As an alternative to Section 7.1.1, where the absorption and specific gravity values are to be used in proportioning concrete mixtures with aggregates used in their naturally moist condition, the
26、 requirement for initial drying to constant mass may be eliminated and, if the surfaces of the particles have been kept wet, the required soaking may also be eliminated. Note 1Values for absorption and for specific gravity in the saturated surface-dry condition may be significantly higher for aggreg
27、ate not oven dried before soaking than for the same aggregate treated in accordance with Section 7.1.1. 7.2. Decant excess water with care to avoid loss of fines, spread the sample on a flat, nonabsorbent surface exposed to a gently moving current of warm air, and stir frequently to secure homogeneo
28、us drying. If desired, mechanical aids such as tumbling or stirring may be employed to assist in achieving the saturated surface-dry condition. As the material begins to dry sufficiently, it may be necessary to work it with the hands in a rubbing motion to break up any conglomerations, lumps, or bal
29、ls of material that develop. Continue this operation until the test specimen approaches a free-flowing condition. Follow the procedure in Section 7.2.1 to determine whether or not surface moisture is present on the constituent fine aggregate particles. It is intended that the first trial of the cone
30、 test will be made with some surface water in the specimen. Continue drying with 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 84-4 AASHTO constant stirring, and, if necessary, work the materia
31、l with a hand-rubbing motion, and test at frequent intervals until the test indicates that the specimen has reached a surface-dry condition. If the first trial of the surface moisture test indicates that moisture is not present on the surface, it has been dried past the saturated surface-dry conditi
32、on. In this case, thoroughly mix a few milliliters of water with the fine aggregate and permit the specimen to stand in a covered container for 30 min. Then resume the process of drying and testing at frequent intervals for the onset of the surface-dry condition. 7.2.1. Cone Test for Surface Moistur
33、eHold the mold firmly on a smooth nonabsorbent surface with the large diameter down. Place a portion of the partially dried fine aggregate loosely in the mold by filling until overflow occurs and heaping additional material above the top of the mold by holding it with the cupped fingers of the hand
34、holding the mold. Lightly tamp the fine aggregate into the mold with 25 light drops of the tamper. Each drop should start about 5 mm (0.2 in.) above the top surface of the fine aggregate. Permit the tamper to fall freely under gravitational attraction on each drop. Adjust the starting height to the
35、new surface elevation after each drop and distribute the drops over the surface. Remove loose sand from the base and lift the mold vertically. If surface moisture is still present, the fine aggregate will retain the molded shape. When the fine aggregate slumps slightly, it indicates that it has reac
36、hed a surface-dry condition. Some angular fine aggregate or material with a high proportion of fines may not slump in the cone test upon reaching a surface-dry condition. This may be the case if fines become airborne upon dropping a handful of the sand from the cone test 100 to 150 mm onto a surface
37、. For these materials, the saturated surface-dry condition should be considered as the point when one side of the fine aggregate slumps slightly upon removing the mold. Note 2The following criteria have also been used on materials that do not readily slump: 1. Provisional Cone TestFill the cone mold
38、 as described in Section 7.2.1, except only use 10 drops of the tamper. Add more fine aggregate and use 10 drops of the tamper again. Then add material two more times using three and two drops of the tamper, respectively. Level off the material even with the top of the mold, remove loose material fr
39、om the base, and lift the mold vertically. 2. Provisional Surface TestIf airborne fines are noted when the fine aggregate is such that it will not slump when it is at a moisture condition, add more moisture to the sand, and at the onset of the surface-dry condition, with the hand lightly pat approxi
40、mately 100 g of the material on a flat, dry, clean, dark, or dull nonabsorbent surface such as a sheet of rubber, a worn oxidized, galvanized, or steel surface, or a black-painted metal surface. After 1 to 3 s, remove the fine aggregate. If noticeable moisture shows on the test surface for more than
41、 1 to 2 s, then surface moisture is considered to be present on the fine aggregate. 3. Colorimetric procedures described by Kandhal and Lee, Highway Research Record No. 307, p. 44. 4. For reaching the saturated surface-dry condition on a single-size material that slumps when wet, hard-finish paper t
42、owels can be used to surface-dry the material until the point is just reached where the paper towel does not appear to be picking up moisture from the surfaces of the fine aggregate particles. 8. PROCEDURE 8.1. Make and record all mass determinations to 0.1 g. 8.2. Partially fill the pycnometer with
43、 water. Immediately introduce into the pycnometer 500 10 g of saturated surface-dry fine aggregate prepared as described in Section 7, and fill with additional water to approximately 90 percent of capacity. Manually roll, invert, and agitate or use a combination of these actions to eliminate all air
44、 bubbles in the pycnometer (Note 3). Accomplish mechanical agitation by external vibration of the pycnometer in a manner that will not degrade the sample. A level of agitation adjusted to just set individual particles in motion is sufficient to promote de-airing without degradation. A mechanical agi
45、tator shall be considered acceptable for 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 84-5 AASHTO use if comparison tests for each six-month period of use show variations less than the accepta
46、ble range of two results (d2s) indicated in Table 1 from results of manual agitation on the same material. Adjust its temperature to 23.0 1.7C (73.4 3F), if necessary by immersion in circulating water, and bring the water level in the pycnometer to its calibrated capacity. Determine total mass of th
47、e pycnometer, specimen, and water. Note 3It normally takes about 15 to 20 min to eliminate air bubbles by manual methods. Dipping the tip of a paper towel into the pycnometer has been found to be useful in dispersing the foam that sometimes builds up when eliminating the air bubbles. Adding a few dr
48、ops of isopropyl alcohol, after removal of air bubbles and just prior to bringing the water level to its calibrated capacity, has also been found useful in dispersing foam on the water surface. Do not use isopropyl alcohol when using the alternative method described in Section 8.2.1. Table 1Precisio
49、n Standard Deviation (1s)aAcceptable Range of Two Results (d2s)aSingle-operator precision: Bulk specific gravity (dry) 0.011 0.032 Bulk specific gravity (SSD) 0.0095 0.027 Apparent specific gravity 0.0095 0.027 Absorption,bpercent 0.11 0.31 Multilaboratory precision: Bulk specific gravity (dry) 0.023 0.066 Bulk specific gravity (SSD) 0.020 0.056 Apparent specific gravity 0.020 0.056 Absorption,bpercent 0.23 0.66 aThese numbers represent, respectively, the (1s) and (d2s) limits as described in ASTM C670. T
