importance of granular layers in flexible pavement
Answers
Answered by
0
Typical layers of a flexible pavement
Typical layers of a conventional flexible pavement includes seal coat, surface course, tack coat, binder course, prime coat, base course, sub-base course, compacted sub-grade, and natural sub-grade (Figure 1).
Seal Coat:
Seal coat is a thin surface treatment used to water-proof the surface and to provide skid resistance.
Tack Coat:
Tack coat is a very light application of asphalt, usually asphalt emulsion diluted with water. It provides proper bonding between two layer of binder course and must be thin, uniformly cover the entire surface, and set very fast.
Prime Coat:
Prime coat is an application of low viscous cutback bitumen to an absorbent surface like granular bases on which binder layer is placed. It provides bonding between two layers. Unlike tack coat, prime coat penetrates into the layer below, plugs the voids, and forms a water tight surface.
Figure 1: Typical cross section of a flexible pavement
Surface course
Surface course is the layer directly in contact with traffic loads and generally contains superior quality materials. They are usually constructed with dense graded asphalt concrete(AC). The functions and requirements of this layer are:It provides characteristics such as friction, smoothness, drainage, etc. Also it will prevent the entrance of excessive quantities of surface water into the underlying base, sub-base and sub-grade,It must be tough to resist the distortion under traffic and provide a smooth and skid- resistant riding surface,It must be water proof to protect the entire base and sub-grade from the weakening effect of water.
Typical layers of a conventional flexible pavement includes seal coat, surface course, tack coat, binder course, prime coat, base course, sub-base course, compacted sub-grade, and natural sub-grade (Figure 1).
Seal Coat:
Seal coat is a thin surface treatment used to water-proof the surface and to provide skid resistance.
Tack Coat:
Tack coat is a very light application of asphalt, usually asphalt emulsion diluted with water. It provides proper bonding between two layer of binder course and must be thin, uniformly cover the entire surface, and set very fast.
Prime Coat:
Prime coat is an application of low viscous cutback bitumen to an absorbent surface like granular bases on which binder layer is placed. It provides bonding between two layers. Unlike tack coat, prime coat penetrates into the layer below, plugs the voids, and forms a water tight surface.
Figure 1: Typical cross section of a flexible pavement
Surface course
Surface course is the layer directly in contact with traffic loads and generally contains superior quality materials. They are usually constructed with dense graded asphalt concrete(AC). The functions and requirements of this layer are:It provides characteristics such as friction, smoothness, drainage, etc. Also it will prevent the entrance of excessive quantities of surface water into the underlying base, sub-base and sub-grade,It must be tough to resist the distortion under traffic and provide a smooth and skid- resistant riding surface,It must be water proof to protect the entire base and sub-grade from the weakening effect of water.
Similar questions