Effect of Bio-enzyme—Chemical Stabilizer Mixture on Improving the Subgrade Properties

Abstract

Conventional methods for strengthening the subgrade soil are time-consuming and are not economically feasible. In this paper, studies were performed to understand the effect of bio-enzyme, bio-enzyme–fly ash mixture and bio-enzyme–lime mixture on kaolinite clay collected from Thonnakkal, Thiruvananthapuram District, Kerala, India. In this study, a popular bio-enzyme known as terrazyme is used as stabilizer. Unconfined compressive strength tests and California bearing ratio tests were conducted on pure soil and soil mixed with terrazyme and its combinations with lime and fly ash. From the study, it was observed that there is a considerable increase in UCC and CBR value for the treated soil compared to untreated one. The optimum dosage of terrazyme obtained was 0.1 ml/kg and that of lime was 8%. With the increase in fly ash content on soil stabilized with terrazyme, an improvement in UCC value was observed, whereas there was not much improvement in CBR value up to 30% addition of fly ash compared to soil stabilized with terrazyme alone. Hence, the combination of terrazyme and lime is an effective method for stabilizing kaolinitic subgrade soil.