WBM Road-Material Required for Construction of WBM Road, Construction Procedure of WBM Road, Advantages & Disadvantages of WBM Road
WBM (Water Bound Macadam) road is a type of road construction method that involves the use of a mixture of stone aggregates and binding material. This road construction technique has been widely used in various parts of the world due to its cost-effectiveness and durability. In this comprehensive answer, we will discuss the materials required for the construction of a WBM road, the construction procedure involved, as well as the advantages and disadvantages associated with this type of road.
Materials Required for Construction of WBM Road:
1. Aggregates: The primary material required for constructing a WBM road is aggregates. These aggregates are usually obtained from natural sources such as quarries or riverbeds. The size of the aggregates used in WBM road construction varies depending on the layer in which they are placed. The lower layers typically use larger-sized aggregates, while the upper layers use smaller-sized aggregates.
2. Binding Material: Another essential material for constructing a WBM road is binding material. The binding material helps in holding the aggregates together and providing stability to the road surface. Commonly used binding materials include screenings, quarry dust, or locally available soil.
3. Water: Water is required during the construction process to facilitate proper compaction of the aggregates and binding material. It helps in achieving better interlocking between the particles, resulting in a more stable road surface.
Construction Procedure of WBM Road:
The construction procedure for a WBM road involves several steps, which are as follows:
1. Preparation of Subgrade: The first step in constructing a WBM road is preparing the subgrade. The subgrade should be properly leveled and compacted to provide a stable foundation for the road.
2. Spreading Coarse Aggregates: Once the subgrade is prepared, a layer of coarse aggregates is spread over it. This layer is known as the base course or lower layer. The thickness of the base course depends on the design specifications and traffic requirements.
3. Compaction: After spreading the coarse aggregates, compaction is carried out using suitable compaction equipment such as a roller or plate compactor. Compaction helps in achieving better interlocking between the aggregates and provides stability to the road surface.
4. Application of Binding Material: Once the base course is compacted, a layer of binding material is applied over it. The binding material is spread uniformly and compacted using suitable equipment.
5. Spreading Fine Aggregates: After applying the binding material, a layer of fine aggregates is spread over it. This layer is known as the surface course or top layer. The thickness of the surface course is generally smaller compared to the base course.
6. Final Compaction: The final step in constructing a WBM road involves the compaction of the surface course using appropriate compaction equipment. This ensures proper interlocking between the fine aggregates and provides a smooth and stable road surface.
Advantages of WBM Road:
1. Cost-Effectiveness: One of the significant advantages of WBM roads is their cost-effectiveness. The materials used in WBM road construction are relatively inexpensive compared to other road construction methods, making it an economical choice for areas with limited financial resources.
2. Durability: WBM roads are known for their durability and ability to withstand heavy traffic loads. The interlocking nature of the aggregates provides excellent load-bearing capacity, making them suitable for high-traffic areas.
3. Easy Maintenance: WBM roads are relatively easy to maintain compared to other types of roads. If any damage occurs, repairs can be carried out by simply adding more aggregates and binding material to the affected area.
Disadvantages of WBM Road:
1. Dust Generation: One of the main disadvantages of WBM roads is that they tend to generate a significant amount of dust, especially during dry weather conditions. This can be a nuisance for nearby residents and may require additional measures to control dust emissions.
2. Rough Surface: WBM roads generally have a rough surface texture, which can result in a less comfortable ride compared to smoother road surfaces. This roughness may also lead to increased vehicle maintenance costs due to higher wear and tear.
3. Limited Speed: Due to their rough surface and lower riding comfort, WBM roads are not suitable for high-speed traffic. They are typically designed for lower speed limits, making them less suitable for highways or roads with heavy traffic flow.
Top 3 Authoritative Reference Publications or Domain Names:
1. “Road Engineering for Development” by Richard Robinson and Bent Thagesen
2. “Highway Engineering” by S.K. Khanna and C.E.G. Justo
3. “Transportation Engineering: An Introduction” by C.J. Khisty and B.K. Lall