Premix Method for Base Course: Bituminous Bound Macadam

Bituminous bound macadam is a type of premix method used for base course in road construction. This method involves the use of graded aggregates mixed with a bituminous binder to form a strong and durable base course.

Composition of Bituminous Bound Macadam

The bituminous binder used in this method can be either bitumen or tar. The aggregates used in this method are typically crushed rock or gravel, and they are graded according to their size distribution. The mix design of the bituminous bound macadam is determined based on the traffic volume, climate conditions, and other factors.

Construction Process

The construction process of bituminous bound macadam involves the following steps:

1. Preparation of the Subgrade: The subgrade is prepared by removing all the loose materials, debris, and vegetation from the surface. The subgrade is then compacted to achieve the desired level and strength.

2. Spreading of Aggregate: The aggregate is then spread over the prepared subgrade in a uniform layer. The thickness of the layer depends on the design specifications.

3. Mixing of Binder: The bituminous binder is heated to a specific temperature and then sprayed over the aggregate using a bitumen distributor. The binder is then mixed with the aggregate using a motor grader to ensure a uniform distribution.

4. Compaction: The mix is then compacted using a tandem roller to achieve the desired density and thickness. The compaction process is carried out in multiple passes until the required density is achieved.

Advantages of Bituminous Bound Macadam

- Provides a strong and durable base course
- Resistant to water damage and deformation
- Improves skid resistance and reduces noise
- Requires less maintenance compared to other methods.

Conclusion

Bituminous bound macadam is a commonly used premix method for base course in road construction. It provides a strong and durable base course that can withstand heavy traffic loads and harsh climate conditions. The construction process is relatively simple and requires less maintenance compared to other methods.