Correct Answer - Option 3 : 25%
Concept:
Stripping value of aggregate:
- Good adhesion between the aggregate surface and bitumen film is mandatory for a durable bituminous pavement.
- Disbanding of bitumen film from the surface of the aggregate in the presence of water or moisture is usually known as stripping.
- The stripping value is defined as the ratio of the average uncovered or stripped area observed visually to the total area of aggregates in each test, expressed as a percentage.
Stripping value = (Uncovered surface area of aggregate by visual examination) / (Total surface area of aggregates)
According to IRC (Indian Roads Congress), the maximum stripping value of aggregate:
- Indian Road Congress (IRC) has specified the maximum value of 25% for aggregates to be used in bituminous road construction.
- Generally, the stripping value of less than 5% is preferred for road aggregates.
- The maximum value suggested by IRC is 10% for aggregates used in open-graded premix carpet.
Hence, According to IRC (Indian Roads Congress), the maximum stripping value of aggregate to be used in bituminous construction like surface dressing is 25%.