Polished Stone Value for Road Surfacing

The question asks about the minimum required polished stone value (PSV) for coarse aggregates used in specific types of road surfacing, according to MORTH (Ministry of Road Transport and Highways) specifications.

The polished stone value (PSV) is a measure of how resistant an aggregate is to polishing under traffic. A higher PSV indicates that the aggregate retains its rough texture better over time, which is crucial for maintaining good friction between vehicle tires and the road surface, especially in wet conditions. This friction is essential for road safety.

MORTH Specifications and PSV

According to the MORTH specifications for road and bridge works, specific requirements are laid down for the properties of materials used in different layers of the road pavement. For the surfacing layers, which are directly exposed to traffic, the aggregates must have adequate resistance to polishing to ensure sufficient skid resistance throughout the life of the pavement.

Aggregate Requirements for Bituminous Concrete and Semi Dense Bituminous Concrete

Bituminous Concrete (BC) and Semi Dense Bituminous Concrete (SDBC) are common materials used for the top wearing course (surfacing) of flexible pavements. These layers are subjected to direct traffic abrasion and polishing.

As per MORTH specifications, the coarse aggregates used in Bituminous Concrete and Semi Dense Bituminous Concrete surfacing require a minimum polished stone value to ensure adequate skid resistance. This requirement is linked to the friction coefficient test.

The specified minimum polished stone value (PSV) for coarse aggregates used in BC and SDBC surfacing should not be less than 55.

Summary of the Requirement

• Test: Friction coefficient test (related to PSV).
• Specification Authority: MORTH.
• Material: Coarse aggregates.
• Usage: Bituminous concrete and semi dense bituminous concrete surfacing.
• Minimum Required PSV: 55.

Therefore, the polished stone value of coarse aggregates used in bituminous concrete and semi dense bituminous concrete surfacing of roads, as per MORTH specifications and related to the friction coefficient test, should not be less than 55.