Explain the construction procedure of Bituminous Road.
1 Answer

The construction procedure of bituminous road is summarized as under:

1) Preparation of sub-grade – The existing ground is made clean to remove dust and other unwanted particles using ordinary and steel brooms. A thin layer of bitumen is sprayed on this clean surface.

2) Preparation of base course – The hard stone aggregate of specified size is spread approximately along the width of road. These stones aggregate(metal) are then compacted using smooth wheel roller or vibratory roller of 6 ton to 10 ton capacity. Now a thin layer of bitumen as prime coat is spread manually or mechanically.

3) Application of surface dressing courses or preparation of bituminous base course (M.P.M) – The tack coat is spread manually or mechanically on prepared base course. Now course aggregate (metal) of size 40 mm to 60 mm is spread uniformly over the treaded base course and rolled with roller. The hot bitumen is spread over the layer of compacted course aggregate (metal) and key aggregates are spread over the bitumen layer followed by roller compaction as per the design camber.

4) Laying of wearing course and seal coat – The wearing surface is laid over one layer of surface course of bituminous mix. The final layer of wearing surface is applied over thin layer of seal coat followed by necessary compaction as per camber and gradient of road.

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