A. Collection of material and equipment:
The various types of material used for the construction of bituminous roads are sub grade soil, subbase course gravel, base course gravel, bitumen of specified grade, kerosene, antistripping agents, diesel, etc. and the equipment’s used for the construction of bituminous roads are excavators, loaders, dumpers, boilers, trippers, distributors, broomers, tractors, etc.
B. Preparation of surface:
The surface to be sprayed shall be thoroughly cleaned by sweeping with mechanical brooms or washing. All loose material shall be swept clear of the layer to expose the full width of the layer upon which prime/tack coat shall be applied. The surface to be sprayed shall be checked for line, camber, and level, and the surface corrected, made good as necessary and approved by the engineer before any bituminous spray is applied. Any water on the surface after spraying shall be allowed to drain away before the prime coat is applied. No traffic shall be allowed on the prepared surface.
C. Prime and tack coats:
The edge of the prepared roadway surface shall be marked out with a line of string or wire pegged. The prime or tack coat shall be sprayed on to it at the specified rate. Spraying shall be carried out not later than 12 hours after the surface has been prepared. The spraying rate of bitumen for prime is normally (0.7 to 1) kg/sq.m and tack coat are as (0.4 to 1.2) kg/sq.m respectively. The temperature of spraying the prime coat is about 700C to 1250C and that of tack coat is about 1800C respectively.
D. Placing a stone chip without bituminous mix or with bituminous mix:
According to the type of pavement surface course, there may application of stone chips only or mixed with bituminous material. The hot mixed material is collected from the mixture by the transporters, carried to the location is spread by mechanical paver. The camber and the thickness of the layer are accurately verified.
E. Rolling and compaction:
A mix after it is placed on the base course is thoroughly compacted by rolling at a speed not more than 5km per hour. The wheels of the roller are kept damp with water. The final rolling or finishing is done by 8-10 tons roller.
F. Quality control:
The routine checks are carried out at site to ensure the quality of the pavement surface. Periodical checks are made for aggregate grading, grade of bitumen, and temperature of aggregate.
G. Finishing:
Finishing includes a proper finish of alignment, clearing undulation, etc. Finishes can be done with machine and by manually. Nowadays, pavers is used as construction of the roads.
