PENGARUH PENAMBAHAN LIMBAH ABU CANGKANG SAWIT (POFA) TERHADAP NILAI CALIFORNIA BEARING RATIO (CBR) UNTUK STABILISASI TANAH LEMPUNG

Abstract

Clay soils are considered to be soils with low bearing capacity. To improve soil conditions, soil stabilization techniques can be applied. One of the soil stabilization techniques is to mix the Palm Oil Fuel Ash (POFA) in clay soil. This study aims to determine the effect of mixing POFA in clay soil on the California Bearing Ratio (CBR) value. The proportions of POFA mixture in the clay soil used were 5%, 10% and 15%. Soils are classified according to the AASHTO classification system. The results of the sieve analysis showed that the percentage of soil that passed sieve number 200 was 70.875% (included in the silt to clay soil group). With a Liquid Limit (LL) value of 34.08% and a Plasticity Index (PI) value of 13.496%, the soil is classified as A-6 which is a clay group with moderate to poor subgrade quality.Based on the results of laboratory CBR testing, it is known that the addition of POFA to clay soil can affect the CBR value. The CBR value increased with the addition of POFA by 5% to 10%. However, there was a decrease in CBR value in the proportion of adding 15% of POFA. The proportion of POFA mixture on clay which gave the highest CBR value was 10%. In this composition the CBR value increased 476,648% from the CBR of the original clay.