AGGREGATE STRIPPING VALUE

AGGREGATE STRIPPING VALUE

CONCEPT AND SIGNIFICANCE:

In absence of the water there is practically no adhesion problem in bituminous constructions. The problems are observed due to presence of water. The test is conducted to determine effects of moisture upon the adhesion of bituminous film to the surface particles of the aggregate. The test is of significance to both bitumen and aggregate because one particle of aggregate may be satisfactorily with one binder and unsatisfactory with the other binder. The same can be said about the binders. The specifications of the ministry of transport and shipping, value by static impression method as per I.S.6241-1971 is recommended.

OBJECTIVES:

To determine stripping value of an aggregate and to ascertain their suitability for bituminous road construction.

APPARATUS:

1.      Thermostatically controlled water bath.

2.      Beaker :- 500 ml capacity

SAMPLE:

The test sample consists of aggregates passing through 25mm I.S. sieve and retained on 12.5 mm I.S. sieve.

PROCEDURE:

1.      Heat the binder to 150 ⁰C TO 175 ⁰C.

2.      Dry, clean and heat the aggregate to 150 ⁰C TO 175 ⁰C and mix with 5% binder by weight of aggregate.

3.       After complete heating, allow the mixture to cool at room temperature in clean and dry beaker.

4.      Add distilled water to immerse the coated aggregates.

5.       Cover the beaker and keep it undisturbed in a thermostatically controlled water bath at 40⁰ C for 24 hours.

6.      Express stripping of aggregate as an average of aggregate surface uncoated by binder. This is to be done by estimating the extent of stripping by visual examination.

PRECAUTIONS:

1.      Aggregate should be thoroughly dried before adding binder.

2.      Distilled water should be used.

3.      Mixing should be done properly.

NOTE:

Three samples can be tested simultaneously so as to arrive at an average value.

RESULT:

The aggregate stripping value was ________.

CONCLUSION:

IRC has recommended that stripping value of an aggregate should not be more than 25% for use in bituminous surface dressing, penetration macadam and carpet construction.