Seal coat in a bituminous road

A seal coat, also known as a surface treatment, is a thin layer of bituminous material that is applied on top of an existing pavement surface to protect it from the damaging effects of the environment and to extend its service life. It is typically used on low-volume roads or as a preventive maintenance measure on higher-volume roads.

Components of a seal coat

The components of a seal coat include:

1. Coarse sand: Coarse sand is one of the main components of a seal coat. It is used to provide texture and skid resistance to the surface. The sand particles are mixed with the bituminous material to form a thin layer that adheres to the existing pavement surface.

2. Bitumen: Bitumen, also known as asphalt, is a sticky, black, semi-solid form of petroleum. It is the binder that holds the seal coat together. Bitumen is mixed with the coarse sand to create a mixture that can be applied as a thin layer on the road surface.

3. Adhesive: An adhesive is added to the bitumen-sand mixture to improve the adhesion between the seal coat and the existing pavement surface. This helps to ensure that the seal coat remains in place and provides effective protection to the underlying pavement.

4. Water repellent agent: A water repellent agent may also be added to the seal coat to enhance its resistance to water infiltration. This helps to prevent the deterioration of the pavement caused by the penetration of water into the underlying layers.

Function of a seal coat

The main function of a seal coat is to protect the underlying pavement from the damaging effects of the environment. It acts as a barrier, preventing water, sunlight, and other harmful substances from penetrating the pavement surface and causing deterioration. Additionally, the coarse sand in the seal coat provides texture and skid resistance, improving the safety of the road surface.

Conclusion

In conclusion, the correct answer to the question is option 'B', which states that a seal coat in a bituminous road consists of coarse sand and bitumen. The coarse sand provides texture and skid resistance, while the bitumen acts as the binder that holds the seal coat together. Adhesive and water repellent agents may also be added to enhance the adhesion and water resistance of the seal coat.