Granular Base Course:
A mixture of soil particles ranging in size from coarse to fine. Processing involve crushing oversized particles and screening where it is necessary to secure the desired grading. The requirements of a satisfactory soil aggregate surface are:
- Resistance to abrasion
- Resistance to penetration of water
- Capillary properties to replace moisture lost by surface evaporation upon the addition of wearing course requirement change.
Successive layers of crushed rock mechanically locked by rolling and bonded by stone screening (rock duct, stone chips etc).
In-water bound Macadam:
The crushed stones are laid, shaped and compacted and then finer materials are added and washed into surface to provide a dense material.
Compose of mineral aggregate and additive to make them strong or more resistant to moisture. Among the treating agents is bitumen.