This article deals with the behaviour of lateritic soils as pavement base for low volume roads. Those soils, abundant in tropical regions, show excellent resistance and low swelling in spite of being plastic. Laboratory test have shown high resilient modulus values, comparable or even superior to those of granular materials ordinarily utilized as pavement base. In tropical regions, besides the absence of the frost/thaw cycle, soil bases frequently deal with equilibrium moisture content below those used in compaction, which provokes shrinkage in lateritic soils and consequently cracks in bases. However, even allowing for water entering the base, swelling of those soils is low and becomes even lower after drying. Moisture content loss in lateritic soils provokes some inhibition of expansibility to those soils, due to dehydration of iron and aluminium hydroxides acting as cementing materials of particles. Therefore, the use of plastic lateritic soils in pavement bases is possible, a concept which traditionally would not be admitted. Loss of moisture content in the bases makes the resilient modulus of lateritic soil improve even more, as shown by lab results. However, as the base shows cracks several millimetres wide, the layer base equivalent resilient modulus is smaller, as it works as a body of blocks separated by cracks. Results of resilient moduli of layers based on backcalculation of elastic deflection dishes obtained in field research are hereby presented. The adoption of local lateritic soils as base material for pavements allows a reduction of 30 to 70% in costs, thus making feasible the construction of large extensions of roads within limited budgets. (A)
Samenvatting