Triple bitumen surface dressing is carried out to improve the condition of existing bitumen paved roads and to protect the base course. It does not have any specific thickness. The thickness varies as per requirement. A thin layer of bituminous material is laced over the existing pavement with aggregates and rolled.
Materials Required For Construction Of Bitumen Surface Dressing!!
The coarse aggregates should be of crushed stones. It should be clean, strong and durable having the following properties:
- Los angles abrasion value (LAA) = 35%
- Aggregate impact value (AIV) = 30%
- Flakiness index(FI) = 25%
- Water absorption = 1%
- Stripping value = 25%
Plants AND Equipment’s Required for Bitumen Surface Dressing !!
- Bitumen heating device
- Mechanical sweeper
- Bitumen Sprayer
- Pneumatic roller
- Aggregate spreader
Construction Steps for Triple Bitumen Surface Dressing!!
- Preparation of existing surface
- Application of prime coat or tack coat
- Application of 16-18 mm stone chippings.
- Rolling the pneumatic roller over the first coat for at least four passes
- Opening to traffic with a controlled lower speed of less than 10 kph for a couple of weeks
- Brooming is done and the loose aggregates are cleaned.
- Application of binder material and 10 mm stone chipping for a second coat.
- Rolling off the second coat by pneumatic roller for at least four passes.
- Opening to traffic with a controlled lower speed of less than 10 kph for one or two weeks
- Once again brooming and cleaning of loose aggregates is done.
- For the third coat, the binder is applied with 8 mm stone chippings
- A pneumatic roller is passed over the third coat at least four passes.
- Finishing and opening to traffic.
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