This Topic Highway Pavements From Highway Engineering And Civil Engineering. The surface of the road ought to be stable and non-yielding, to permit the serious wheel a lot of road traffic to maneuver with least doable rolling resistance. The paved surface ought to even be even on the longitudinal profile to alter the quick vehicles to maneuver safely and well at the look speed. At high moisture contents, the soil becomes weaker and soft and starts yielding under heavy wheel loads, thus increasing the resistance to traction. The earth road may not be able to fulfill any of the above requirements, especially during the varying conditions of traffic and the weather changes. Therefore a pavement consisting of superior and stronger materials is laid over the prepared earth surface which could fulfill the above requirements.
The objective of laying a pavement is to support the wheel loads and to transfer the load stresses through a wider area on the soil subgrade below. Thus the magnitude of stresses transferred to the subgrade soil through the pavement layers is considerably lower than the contact pressure or compressive stresses directly under the wheel load applied on the pavement surface. The reduction in the wheel load stress due to the pavement depends both on its thickness and the characteristics of the materials used in the different pavement layers placed over the soil subgrade. A pavement layer material is considered more effective or superior if it is able to distribute the wheel load stress through a larger area per unit thickness of the layer.
Depending on the vertical alignment and the environmental conditions of the site the pavement may be constructed over an embankment, cut or almost at the gro level itself. It is always desirable to construct the pavement well above the maximum level of the groundwater or the highest water table, to keep the subgrade soil relatively dry even during monsoon season.