MATERIALS FINE THAN 75 MICRON (NO. 200) SIEVE IN MINERAL AGGREGATES BY WASH

VI. STANDARD TEST METHOD (ASTM C 117) MATERIALS FINE THAN 75 MICRON (NO. 200) SIEVE IN MINERAL AGGREGATES BY WASH

1. Scope, Significance, Use:

1.1 This test method covers the determination of the amount of material finer than a 75micron (No.200) sieve in aggregates by washing, Clay particles and other aggregate particles that are dispersed by the wash water, as well as water-soluble materials, will be removed from the aggregates during the test.

S S Washed in a prescribed manner

1.2 A sample of the aggregates is washed in a prescribed manner, using water. The decanted wash water, containing suspended and dissolved material, is passed through a 75 micron (No.200) sieve. the loss in mass resulting from the wash treatment is calculated as mass percent of the original

Sample and is reported as the percentage of material finer than a 75 micron (No. 200) Sieve by

washing.

1.3 Material finer than the 75 micron (No. 200) sieve can be separated from larger particles much

more efficiently and completely by wet sieving than through the use of dry sieving. Therefore, when

accurate determinations of material finer than 75 micron in fine or coarse aggregate are desired, this

test method is used on the sample prior to dry sieving in accordance with Method C 136 (Sieve

Analysis). The results of this test method are included in the calculation in Method C 136, and the

total amount of material finer than 75 micron by washing, plus that obtained by dry sieving the same

sample, is reported with the results of Method C 136. Usually, the additional amount of material finer

than 75 micron obtained in the dry sieving process is a small amount. If it is large, the efficiency of

the washing operation should be checked. It could, also, be an indication of degradation of the

aggregates.

MATERIALS FINER THAN No. 200 (75 µm) SIEVE IN MINERAL AGGREGATES BY WASHING,material finer than 75 micron test, Materials Finer than 75-μm (No. 200) Sieve in Mineral Aggregates by Washing

2. Additional Apparatus:

Sieves-A nest of two sieve, the lower being a 75 micron (No.200) sieve and the upper a 1.18-mm

(No. 16) sieve, both conforming to the requirements of Specification E 11.

3. Sampling:

3.1 Sample the aggregates in accordance with Practice D 75, If the same test sample is to be tested

for sieve analysis according to Method C 136, comply with the applicable requirements of that test

method.

Sample of aggregates to be

3.2 Thoroughly mix the sample of aggregates to be tested and reduce the quantity to an amount suitable for testing using the applicable methods described in PracticeC 702. If the same test sample

is to be tested according to Method C 136, the minimum mass shall be as described in the applicable sections of that method. Otherwise, the mass of the test sample, after drying, shall conform with the

following:

Nominal Maximum Size Minimum Mass, gm

2.36mm (#8) 100

4.75mm(#4) 500

9.5 mm (3/8 in.) 1,000

19.0mm (3/4 in.) 2,500

37.5mm (1.5 in.) or larger 5,000

The test sample shall be the end result of the reduction. Reduction to an exact predetermined mass shall not be permitted.

4. Procedure:

41 Dry the test sample to constant mass at a temperature of 110+5°C (230+9°F). Determine the

mass to the nearest 0.1% of the mass of the test sample.

4.2 If the applicable specification requires that the amount passing the 75 micron (No.200) sieve

Shall be determined on a portion of the sample passing a sieve smaller than the nominal maximum

size of the aggregates, separate the sample of the designated sieve and determine the mass of the

material passing the designated sieve to 0.1% of the mass of this portion of the test sample. Use this

mass as the original dry mass of the test sample in Section 5.

NOTE : some specifications for aggregates with a nominal maximum size of 50 mm or greater, for example, provide a Limit for materials passing the 75 micron (No.200) sieve determined on that portion of the sample passing the 25.0 mm sieve. Such procedures are necessary since it is impractical to wash samples of the size required when the same test sample is to be used for sieve analysis by Method ASTM C 136.

4.3 After drying and determining the mass, place the test sample in the container and add sufficient

water to cover it. Agitate the sample with sufficient vigour to result in complete separation of all

particles finer than the 75 micron (#200) sieve from the coarser particles, and to bring the fine

material into suspension. Immediately pour the wash water containing the suspended and dissolved

Solids over the nested sieves, arranged with the coarser sieve on top. Take care to avoid, as much as

feasible, the decantation of coarser particles of the sample.

4.4 Add a second charge of water to the sample in the container, agitate, and decant as before.

Repeat this operation until the wash water is clear.

NOTE: If mechanical washing equipment is used, the charging of water, agitating and decanting may be a continuous operation.

4.5 Return all material retained on the nested sieves by flushing to the washed sample. Dry the

washed aggregates to constant mass at a temperature of 110+5°C (230+9°F) and determine the mass to the nearest 0.1% of the original mass of the sample.

NOTE: Following the washing of the sample and flushing any material retained on the 75 micron (#200) sieve back into the container, no water should be decanted from the container except through the 75 micron sieve, to avoid loss of material. Excess water from flushing should be evaporated from the sample in the drying process.

5. Calculation:

Calculate the amount of material passing 75 micron (#200) sieve by washing as follows:

A =B-C/B x 100

where

A = percentage of material finer than a 75 micron (#200) sieve by washing

B = original dry mass of the sample, in grams, and

C = dry mass of sample after washing, in grams

6. Report:

Report the percentage of material finer than the 75 micron (No.200) sieve by washing to the nearest

0.1%, except if the result is 10% or more, report the percentage to the nearest whole number.