Influence of chemical stabilization method and its effective additive concentration (EAC) in non-pavement roads. A study in andesite-based soils

摘要

Unpaved roads can be affected by high traffic demand and environmental conditions, decreasing its serviceability. To improve mechanical performance and reduce maintenance costs in soils, chemical stabilization techniques have been widely used and it is additive selection depends mainly on the available soil. In this research, an experimental study for different soil-additive combinations was conducted and analyzed, considering several soils based in andesitic rocks, for analyzing soil strength improvement after chemical stabilization. The results showed a dependency regarding the grain size distribution of the soil, but also on the plasticity index and the moisture content of the sample, which differs significantly from some literature guidelines. Proper conditions of soil characteristics and water-additive concentration may lead up to an increase of twice the initial soil strength. The concentration of additive per unit volume of wet soil leads to define an Effective Additive Concentration (EAC) parameter, that provides an optimal increase of soil shear strength. It is proven that exists a clear tendency of optimal EAC value for asphalt or polymeric additives, as well as some tendencies for enzymatic additives that need to be further developed, due to its dependence on the chemical composition of the soils.