Improvement of peat soil using microorganisms for subgrade reviewed from CBR value

Peat soil is well known as problematic soil because of its poor geotechnical properties such as high-water content, low shear strength, high organic matter, low bearing capacity and high compressibility. Due to these geotechnical issues of peat soil, improvement of the soil is essential in order to enhance its engineering properties. Peat soils are formed from a mixture of fragments of organic material originating from decaying plants, whether weathered or not. The physical and mechanical characteristics of peat soil are strongly influenced by the degree of decomposition. To accelerate the decomposition of peat soil is to add microorganisms. The microorganisms are used as the soil stabilizer in order to investigate the optimum percentage of microorganism as the stabilizing agent on peat soil. The purpose of this research is to investigate the physical and mechanical changes in fibrous peat soil of laboratory test after adding microorganisms. The volume of Microorganisms added and mixed with peat soils varied with 5 %, 10 %, 15 %, and 20 %. There are 4 variation percentage of microorganisms to dry soil such as laboratory test are fiber content, ash content, organic content, acidity level (pH), compaction (standard proctor test), California bearing ratio. The variation of the highest CBR were treatment in 7, 14, 28 days. The results show that microorganisms improve the physical and mechanical properties of peat soil. The most significant result on the physical and mechanical properties of peat soil was 20 % microorganisms. The increase value of unsoaked CBR from 2.86 % to 10.47 % and in soaked condition from 2.51 % to 9.24 %.