A Soil-Cement Formulation for Road Pavement Base and Sub Base Layers: a Case Study

The transport sector is a key element in societal development and economic growth, with road transport playing a dominant role. The minimisation of economic and environmental costs throughout the road structure lifecycle without compromising the performance is a major concern. As such, the use of local treated soils with cement can be a good alternative to base and sub base road pavement layers. The objective of this laboratory study was to formulate a soil-cement solution for applying as base and sub base layers in an experimental test section. The formulation was realised according two different methodologies: the Portuguese and the South African. Local clayey sand was used to the formulation process. Aiming to assess the soil-cement mechanical behaviour, unconfined compressive strength and indirect tensile strength tests on soil-cement specimens with different curing times (1, 7, 14, 21, 28, 60, 90, 120, 150 and 180 days) were realised. Strengths determined for both methodologies showed significant differences between them and also variations between the results obtained for the specimens presenting the same curing time. The strengths determined according to the South African standards are generally higher than the same characteristics measured according to the European standards. In addition, the results obtained by the South African standards show a better repeatability than those obtained according to the applied European standards. For the studied clayey sand, the obtained results suggest a minimum curing period of 28 days when about 90 and 70% of maximum unconfined compressive strength and indirect tensile strength, respectively, obtained according to the South African methodologies were achieved.