The Utilization of Volcanic Ash and High Rusk Ash as Material Stabilization in Clay by Unconfined Compression Test (UCT) and California Bearing Ratio (CBR)

Abstract

Clay is a type of soil which needs to be stabilized. The method often used is stabilization by adding additive to the soil. In this study, the additive materials that we use are Volcanic ash from Mount Sinabung and rice husk ash. The selection of these materials as additive is based on their silica content. Volcanic ash has a high silica content that is equal to 82.04%, and rice husk ash also has a high silica content which is equal to 89.8%. This study aims to improve the physical and mechanical properties of soil. Clay used or this study was taken from Patumbak, Deli Serdang, the volcanic ash was taken from Mount Sinabung, and the rice husk ash was produced from the bricks burning outcome in Stabat Langkat. The tests for soil are water content test, specific gravity test, Atterberg limits test, sieve analysis test, compaction test, CBR (California Bearing Ratio) laboratory test, and Unconfined Compression Test (UCT). The test results show that the value of liquid limit in addition of volcanic ash and rice hush decreased gradually. So does the plasticity index, the value decreased from 26.33% to 5.31% on the addition of 2.5% volcanic ash + 22.5% rice husk ash. While on the mechanical properties, the optimal CBR value obtained in the addition of 75% soil + 25% volcanic ash is 15.48%, and the addition of 25% volcanic ash causes soil increases the compressive strength from 1.38 kg/cm2 to 2.23 kg/cm2. Unconfined Compression Test result shows that the compressive Strength (qu) of original soil is 1.38 kg/cm² value, meanwhile the Compressive Strength (qu) of remoulded soil is 0.58 kg/cm2.