Highway Materials Engineering

RUTTING DUE TO UNSTABLE MIX:
The other main reason of rutting is unstable mix, in this case the deformation is limited to the asphalt layer and will result in an upheaval at the edge of the rut. While this might suggest that rutting is an asphalt binder problem, it is more correct to address rutting by considering the combined mineral aggregate and binder properties and through gradation and volumetric proportioning.

RUTTING DUE TO POOR SUBGRADE:
One of the main causes of rutting is subgrade
failure, this type of deformation can occur in the subgrade or underlying layers such as base or sub-base rather than the asphalt layers. It is because of poor in situ subgrade quality or condition required for the pavement structure and loading conditions. Stiffer paving materials may reduce this type of rutting, but it is better to correct the instability of subgrade or underlying layer.

Soil used for Earthworks in Highway construction shall comprise:- 🚧👷
1) Organic material must not exceed than 2%.
2) Liquid Limit maximum 40%.
3) Plasticity Index maximum 6%.
4) Maximum rock particles size 63mm.
5) CBR not less than 16%.
6) Material shall not contain excess of fines, maximum 20% passing of .063mm sieve or No. 230 sieve.

Soil Definition in Highway Engineering: An assemblage of discrete particles in the form of deposit, usually of mineral composition but some time of organic origin, which can be separated by gentle mechanical means & which includes variable amounts of water & air. A soil commonly consists of naturally occurring deposits forming part of the earth crust, but the term is also applied to made ground consisting of replaced natural soil or man made material exhibiting similar behavior, e.g. crushed rock (Sub-Base, Aggregate Road Base, Wet-Mix), crushed blast-furnace slag, fly-ash. In the up coming video we will discuss all the tests conducted on Soil shortly, Later we will discuss & explain each test briefly.