BITUMENOUS ROAD AND CONSTRUCTION
Bituminous road consist of their surface with bituminous materials which
is also called as Asphalt. It is sticky dark viscous liquid obtained
from natural deposits like crude petroleum.
Materials Required :
The grade of bitumen to be used for this type of road suggested by IRC ranges from 80/ 100, 60/ 70 & 30/ 40. Any one of the above grade can be adopted.
Road tars of grades such as RT-4 & RT-5 can also be used.
Equipments and Plants Required :
1. Bitumen heating device.
2. Bitumen distributor.
3. Roller for compacting operation.
4. Aggregate spreader.
Construction Procedure of Bituminous Penetration Macadam Road :
• Preparation of Existing Surface :
First of all the surface on which bitumen macadam is to be applied is cleaned from dust and other debries. The gradient and the camber of the road is properly checked. Priming coat can be also applied if necessary for porous surfaces.
• Spreading of Course Aggregates :
Spreading of aggregates can be done manually or by machine. To achieve the desired profile in cross-section, template cat or camber profile may be used.
• Rolling Operation :
After speeding of aggregates they are dry rolled with a minimum of 10 tonnes roller. It is assured that the aggregates are properly compacted and interlocked.
• Bitumen Application :
The uniform layer of bitumen binder is applied on the dry rolled compacted aggregates with the help of pressure distributor or mechanical hand sprayer.
• Spreading of Key Aggregates :
Once the bitumen is properly applied key aggregated are properly laid and rolling operation again continued for proper compaction. Cross Profile is also checked at the same time.
• Seal Coat Application :
If the road is going to be made open for the traffic and another surface course is not required then the seal coat is applied. It consist of sand bitumen or it may be of surface dressing type.
• Finishing :
Cross profile of the road should be checked with template and the longitudinal profile by straight edge of the road. The permissible undulation on 3 m road is 12 mm.
• Open to Traffic :
The road is made open to traffic after minimum of 24 hours after its construction.
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