Stripping value of Road aggregates as per IS 6241
AIM:
To determine the stripping value of road aggregates.
THEORY
This test is conducted to determine the effect of moisture upon the adhesion of the bituminous film to the surface particles of the aggregate. This test is of significant value to ascertain the suitability of the two materials viz. bitumen (binder) and aggregates because one particular aggregate may be satisfactory with one binder and unsatisfactory with another; and the same being true for the binders. The specifications of ministry of transport and shipping recommend the determination of stripping value by the static immersion method in accordance with IS: 6241-1971.
NEED & SCOPE
This method aggregates binders are covers the procedure for determining the stripping value of by static immersion method, when bitumen and tar used .
ADHESION WITH BITUMEN
The aggregates used in bituminous pavements should have less affinity with water when compared with bituminous materials; otherwise the bituminous coating on the aggregate will be stripped off in presence of water.
APPARATUS:
CALCULATION
Road aggregate stripping value = percent fines = W2/W1 x 100
RESULT:
The result is reported as the percentage of stone surface that remains coated for the specified periods, the mean value of at least three estimated values, being rounded off to the nearest 5 percent.
PRECAUTION:
Care shall be taken while mixing aggregates with bitumen.
AIM:
To determine the stripping value of road aggregates.
THEORY
This test is conducted to determine the effect of moisture upon the adhesion of the bituminous film to the surface particles of the aggregate. This test is of significant value to ascertain the suitability of the two materials viz. bitumen (binder) and aggregates because one particular aggregate may be satisfactory with one binder and unsatisfactory with another; and the same being true for the binders. The specifications of ministry of transport and shipping recommend the determination of stripping value by the static immersion method in accordance with IS: 6241-1971.
NEED & SCOPE
This method aggregates binders are covers the procedure for determining the stripping value of by static immersion method, when bitumen and tar used .
ADHESION WITH BITUMEN
The aggregates used in bituminous pavements should have less affinity with water when compared with bituminous materials; otherwise the bituminous coating on the aggregate will be stripped off in presence of water.
APPARATUS:
- Heat resistant glass beaker of 500 ml capacity.
- 20mm and 12.5mm IS sieves.
- Bitumen mixer.
- Balance (capacity 10 kg).
- Water bath preferably with a thermostat.
- 200 gm of dry clean aggregates passing 20 mm IS sieve and retained on 12.5 mm sieve are heated up to 150 degree when these are to be mixed with bitumen and the aggregates are heated up to 100 degree when these are to be mixed with tar.
- Five percent by weight of bitumen binder is heated to 160 degree (110 degree in the case of tar binder).
- The aggregate and binder are mixed thoroughly till they are completely coated and mixture is transferred to a 500 ml beaker and allowed to cool at room temperature for about two hours .
- Distilled water is then added to immerse the coated aggregates.
- The beaker is covered and kept in a water-bath maintained at 400C taking care that the level of water in the water - bath is at least half the height of the beaker.
- After 24 hours the beaker is taken out cooled at room temperature and the extent of stripping is estimated visually while the specimen is still under water.
- The stripping value is the ratio of the uncovered area observed visually to the total area of aggregates in each test, expressed as percentage.
- The mean of three results is reported as stripping value of the tested aggregates and is expressed as the nearest whole number.
CALCULATION
Road aggregate stripping value = percent fines = W2/W1 x 100
RESULT:
The result is reported as the percentage of stone surface that remains coated for the specified periods, the mean value of at least three estimated values, being rounded off to the nearest 5 percent.
PRECAUTION:
Care shall be taken while mixing aggregates with bitumen.
