Improvement of clay gradation using black-beach sand.

Stabilization is one method of improving soil that does not meet development requirements. This method is used to enhance the technical properties of the soil so that it can fulfill particular technical specifications. Due to the low bearing capacity of clay soil, this study was conducted to increase soil gradation using black-beach sand by adding 0%, 5%, 10%, 15%, and 20% clay to the soil. Water content and specific gravity tests were performed on black-beach sand, as well as physical (water content, specific gravity, Atterberg limits, and soil grain analysis) and mechanical properties (compaction and shear strength) testing on clay soils. The black-beach sand test resulted in a water content of 2.51% and a specific gravity of 2.676. The results of the physical properties test on clay showed a decrease in the water content, specific gravity, liquid limit, plasticity index, and percentage of passing No. 200, but an increase in the plastic limit and shrinkage limit values. Clay is classified as A-7-5 by AASHTO and as CH by the USCS. The optimal water content value decreased as the maximum dry soil volume increased. The original soil shear strength test resulted in a value of 0.863 kg/cm2, a cohesion value of 0.557 kg/cm2, and an internal friction angle of 11.08°. The internal friction angle increases with the addition of black-beach sand, but the cohesiveness value decreases. Stabilization with black-beach sand can increase the gradation and bearing capacity of the soil. [ABSTRACT FROM AUTHOR]