Describe the detailed procedure of construction of water bound macadam road

The procedure of construction of water-bound macadam road:

1. Preparation of The Foundation

The foundation for receiving the new layer of W.B.M may be either the subgrade or subbase course. This foundation layer is prepared to the required grade and camber and the dust and other loose materials are cleaned.

On the existing road surface, the depression & potholes are filled and the corrugations are removed.

2. Provision of Lateral Confinement

This can be done by constructing the shoulders to a thickness equal to that of the compacted W.B.M layer and trimming the inner sides vertically.

3. Spreading of Coarse Aggregates

The coarse aggregates are spread uniformly to the proper profile and even thickness upon the prepared foundation and checked by templates.

4. Rolling

After spreading the coarse aggregates properly, compaction is done by a three-wheeled power roller (6 to 10 tones) or equivalent vibrating roller.

Starting at the margins and progressively moving towards the centre of the rod road, rolling is done until enough compaction is attained.

Rolling on the super-elevated part began at the inner or lower edge of the pavement and eventually moved to the outer or upper edge.

5. Application of Screenings

Dry screenings are put progressively across the surface once the coarse aggregates have been suitably rolled, with trial rolling continuing as the screenings are spread. At the same time, brooming is being done.

6. Sprinkling and Grouting

The surface is sprayed with water, swept, then rolled after the screens are applied.

7. Application of Binding Material

Following the application of screens and rolling, binding materials are applied in two or more thin layers at a uniform and slow rate. The surface is sprayed with water after each application of the binding substance, and the wet slurry is swept with brooms to fill the spaces.

8. Setting & Drying

The W.B.M course is left to set overnight after the final compaction. The Hungry places are filled with screens or binding materials the next day, softly watered if needed, and rolled. There will be no traffic until the W.B.M layers have set and dried.