Mechanical performance of different stabilised soils for application in stratified ground

To achieve homogeneity in soil mixing along the depth of a column in a non-homogeneous layered soils, it is necessary to understand the effect of soil type on the treatment and to adapt the treatment for the different soil strata. For this purpose, an extensive laboratory testing programme was carried out to examine the effect of different soils and cement content on the mechanical and physical properties of the resulting treated soils. Four different soils, namely gravely sand; silty clayey gravely sand, silty clay and a pure clay were tested. Different grout constituents, constituent ratios, dosages and water content were used in order to improve the performances of the mixes using Portland cement as the main binder. The tests performed included unconfined compressive strength, from which the elastic stiffness was also calculated, and permeability at 28 days. The results show that relatively homogenous results in terms of compressive strength and permeability may be reached by modifying the cement-bentonite ratio in granular soils and the binder dosage in fine-grained soils. The results constitute a preliminary useful guide to adapt in the construction techniques in field applications.