Comparative Analysis of Soil Shear Strength Stabilization of Paya Tumpi Soft Clay with Burni Telong Volcanic Ash – Wih Pesam

Abstract

Silty clay soil a quarry in Paya Tumpi, Kebayakan, West Aceh, is a source of backfill material that is often used for road construction in the area. This clay can be divided into three types based on its color, namely red, yellow, and gray. These three types of soil have bad properties that make them unsuitable for use as road base layers. Therefore, it is necessary to stabilize it using a mixture of volcanic ash taken from Wih Pesam and Bener Meriah. The purpose of this study was to evaluate the effect of mixing soil with volcanic ash on the shear strength of the soil. This research method involves compaction testing with a standard proctor and direct shear strength testing on a mixture of soil and volcanic ash. Variations in the addition of volcanic ash are 12.5%, 15%, 17.5%, and 20% of the dry weight of the soil. The results showed that the three soil types were included in the soil classification A-7-6 according to AASHTO, and the presence of minerals was detected in montmorillonite on gray soil. The addition of volcanic ash only increases the cohesion value of the gray soil in several variations of the mixture. The cohesion values for the various soil and volcanic ash mixtures of 0%, 12.5%, 15%, 17.5%, and 20% are as follows: for red soil, the cohesion values are 0.492, 0.408, 0.452, 0.088, respectively, and 0.344 in units of kg/cm2; for yellow soil, the cohesion values were 0.585, 0.562, 0.579, 0.243, and 0.327 in units of kg/cm2; while for gray soil, the cohesion values were 0.037, 0.453, 0.433, 0.206, and 0.031 in units of kg/cm2, respectively.