Adding calcite and nanocalcite to improving the plastic properties of the lean clay

Abstract

The stabilization of the problematic soils with the calcite and nanocalcite is one of the economically efficient methods in civil projects. The current study evaluated the effect of calcite and nanocalcite on the plastic properties of the clayey soil obtained from the north-east of Iran. The origin of this clay was the loess soil classified as CL in the unified classification system. The purpose of this study was to investigate the effect of adding typical calcite powder and nanocalcite powder (based on the type and amount) on the performance of the improved soil in these two materials. The ball mill machine was used for preparing the nanocalcite. According to the results of X-Ray and SEM tests, the chemical composition of the nanoparticles after crushing was similar to the initial chemical compound of the main powder. The Atterberg limit tests were conducted by adding different weight percentages of calcite including 3, 4, 6 and 7 wt% and nanoparticles of calcite including 0.5, 1, 1.5 and 2 wt%. The results indicated that adding calcite led to the decrement of the plastic index and increment of plastic limit in the studied clayey soil. Furthermore, the mixing percent of the nanocalcite was considerably lower than the typical calcite, but the effect of nanocalcite on improving the clayey soil properties was similar to the calcite particles. Accordingly, the activity of calcite particles in the soil was highly increased due to the crushing of calcite particles in nanoscale and the increase in the specific surface.