Subgrade Stabilization and Pavement Recycling for the Widening of the A-495 Highway in Huelva (Spain)

The upgrading of the A-495 between Gibraleón and San Bartolomé, in the province of Huelva (SouthWest of Spain), consists in an widenig of the cross section (which some years ago has been enlarged from 6 m in the original work to 8 m after a first rehabilitation) to 10 m and a strengthening of the pavement. In de design phase, widenings comprising unbound aggregate and soil layers were selected. This solution presented several problems. The diferent stiffness in the cross section could result in longitudinal cracking, as it occurred in the past when the first widening was performed. Also, the aggregates needed are far away from the location of the road. These difficulties made advisable a change in the design. In the widenings, both the upper layers of the subgrade and the base of the pavemand were treated with cement, as well as the part of the existing pavement not affected by the widening process. Then some layers of bituminous mixyures were placed om the soil-cement base made of cement treated virgin aggregate and cement reycled pavement. From the experience of these works it can be concluded that soil stabilization and pavement recycling using cement are two very suitable techniques for widening and improving the bearing capacity of existing two-way roads.