1. Preparation of the existing base course layer
The existing surface is prepared by removing the pot holes or rust if any. The irregularities are filled in with premix chippings at least a week before laying surface course. If the existing pavement is extremely way, a bituminous leveling course of adequate thickness is provided to lay a bituminous concrete surface course on a binder course instead of directly laying it on a WBM
2. Application of Tuck Coat
It is desirable to lay AC layer over a bituminous base or binder course. A tack coat of bitumen is applied at 6.0 to 7.5 kg per 10 sq.m area, this quantity may be increased to 7.5 to 10 kg for non-bituminous base.
3. Preparation and placing of Premix
The premix is prepared in a hot mix plant of a required capacity with the desired quality control. The bitumen may be heated upto 150 – 177 deg C and the aggregate temperature should not differ by over 14 deg C from the binder temperature. The hot mixed material is collected from the mixture by the transporters, carried to the location is spread by a mechanical paver at a temperature of 121 to 163 deg C.
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 routine checks are carried out at site to ensure the quality of the resulting pavement mixture and the pavement surface.
Periodical checks are made for
a) Aggregate grading
b) Grade of bitumen
c) Temperature of aggregate
d) Temperature of paving mix during mixing and compaction.