EFFECT OF ORGANIC WASTE MATERIALS ON CLAYS SOIL PROPERTIES

Abstract

Clay soil has cohesive properties which cause the soil to be hard when dry and plastic when wet, which can cause damage to the construction of the building above it. One method of improving unstable soil is soil stabilization using additives. In this study, the mixed materials used were waste materials, namely rice husk ash, coconut shell ash, and sawdust ash with a proportion of 2%, 5%, and 8% respectively. Each of these materials is added with 5% sea shell powder as a substitute for lime. Soil sampling was carried out at the location of Koto Baru Nan XX Village, Padang City. The method used is the observation method, which is testing the physical and mechanical properties of the soil in the laboratory. The results showed that the value of the plasticity index was reduced the most by mixing coconut shell ash and sea shell powder to 87%. The optimum water content and dry unit weight of soil with added materials decreased during the compaction test. The optimum moisture content and dry unit weight dropped sharply when sawdust ash and shell powder were mixed by 57% and 9%, respectively, when viewed from their average values. Then followed by a mixture of coconut shell ash and sea shell powder of 47% and 15%. And the smallest decrease occurred in a mixture of rice husk ash and sea shell powder at 31% and 11%. The level of soil sensitivity is reduced the most in a mixture of sawdust ash and sea shell powder by 50% and continue by a mixture of coconut shell ash and sea shell powder by 43% and a mixture of rice husk ash and sea shell powder by 24%.