Semi-rigid pavement performance and construction techniques for semiarid areas

This article explains a field study about the service properties of semi-rigid pavements attained in a climatic area that can be considered semiarid/arid, located in the west of Spain. A semi-rigid pavement includes a soil-cement (SC) base (or subbase) and a stabilised subgrade. Taking as a reference the works in two motorways of recent construction such as the A-66 and A-58, the criteria are presented that favoured the choice of the semi-rigid solution for its pavement and the specific techniques used for its building as well as its performance after having been opened to the traffic for 7–8 years. It has to be noted, however, that the treated layers, especially the SC base, need to be protected by a specific thickness of bituminous layers in order to achieve a homogeneous distribution of the traffic loads and provide protection against water, as well as to absorb part of the thermal cracks that will inevitably appear. Nevertheless, in the considered weather conditions, the use of pre-cracking techniques is necessary in order to maximise cement content and obtain higher bearing capacity. The SC course, resting on a quality subgrade, is responsible to a great extent for the pavement final stiffness, being able to reduce the deformability of the subgrade itself to over 40%. The results reached with the International Roughness Index regularity rate on the treated subbases are presented as well, displaying its evolution with regard to the pavement construction phases and remarking on the recommended strategies for its improvement.