The effect of high alkali solvent additive on physicomechanical properties of andesitic residual soils

Construction on the problematic ground is increasing day by day due to the increasing population ratio and urbanisation. Solfasol district, located at the north of Ankara, is a region where new and multi-storey buildings have begun to be constructed under the influence of urbanisation. In this study, it was tried to develop an alternative method of soil remediation if andesitic residual soils in the Solfasol Quarter were opened to construction. In this scope, it was aimed to improve andesitic residual soils with the high alkaline solutions. Samples were obtained from three different residual soils in the study area for laboratory experiments, which can be distinguished by observations. Sieve analyses, density, moisture content determination, liquid limit, plastic limit, uniaxial compressive strength, modulus of elasticity, free swell index, consolidation tests were carried out. Changes in physicomechanical properties were investigated by adding NaOH basic solution at 5% and 10% to different soil samples. At the same time, the duration of the cure was examined within the scope of the study. NaOH-containing samples were cured for 1, 7, 28 and 56 days, and changes in strength values were determined. The microscopic changes in the structure of the soil sample were observed with SEM images. The effect of NaOH on the water retention capacity and thus the relationship between expansion and shrinkage were determined. The relationship between moisture content and uniaxial compressive strength was determined. By interpreting the results, the effect of a single basic solution (NaOH solution) on the andesitic residual soils was determined, and it was evaluated that it can not be an alternative to materials with binding properties such as cement. It was understood that a single NaOH solution added affects the uniaxial compression strength negatively.