STUDY ON THE INFLUENCE OF SAND GRADATION ON SHEAR STRENGTH, DENSITY, AND SWELLING OF EXPANSIVE SOILS STABILIZED WITH SAND.

• Main Author: Tanadi, Billy
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/66936
• Institution: Institut Teknologi Bandung

Expansive soil is soil that experience volume changes when there is a change in water content. This expansive property is caused by the type of mineral in the expansive soil. Changes in the volume of expansive soil will damage the structure at the soil surface,. As a tropical country dominated by clay soil, Indonesia has a number of areas with expansive soil. Therefore, it is necessary to identify and improve expansive soil in Indonesia. In this study, an attempt was made to identify soil minerals and their mineral content. The mineral content that causes expansive properties in the soil was identified by X-Ray Diffraction test. The soil sample in this study was expansive soil from Cikarang, Bekasi Regency, West Java. The mineral that causes expansive properties in the soil sample is nontronite with 19.84% content. In this study, an expansive soil improvement effort was also carried out with the addition of sand. Sand has several properties that have the potential to be used to stabilize expansive soils, such as not having plasticity, not being expansive, and high workability. In this study, three types of sand with different gradations were used, namely uniformly graded sand with small grain size, continuously graded sand with medium grain size, and continuously graded sand with large grain size. Laboratory tests of Atterberg limit test, Standard Proctor compaction test, unconfined compressive strength test, 1-dimensional expansion test , and methylene blue spot test were performed on soil samples before and after mixing with sand. The goal was to determine optimum sand content and optimum gradation to improve the expansive soil in terms of density, shear strength, and expansion. It was found that the addition of sand reduces the Atterberg limit, increases maximum dry density, reduces optimum moisture content, increases shear strength to a certain sand content, and reduces the value of methylene blue value. The addition of sand doesn’t have any effect on swelling potential and swelling pressure. Sand with uniform gradation and small grain size is most effective in increasing shear strength, decreasing optimum moisture content, and showing a decreasing trend in swelling pressure. Meanwhile, sand with a well graded gradation and large grains shows most reduction in the methylene blue value and showed a decreasing trend in swelling potential. There is no effect of the sand gradation on the decrease of Atterberg limit and the increase of maximum dry density.