Laboratory Investigation of Black Cotton Soil Modified with Bioenzyme and Aggregates for Pavement Subgrade

Abstract

The major component of the pavement layer is subgrade soil, but the availability of good quality of subgrade soil is not abundantly available in most part of the South India, which includes North Karnataka, Maharashtra, Madhya Pradesh and Gujarat, due to the presence of clayey soil or Black cotton BC soil. This soil is having high plasticity index, high volumetric change behavior and poor load carrying capacity, hence it is not suitable for subgrade layer of the pavement. As there is a shortage of availability of good quality soil so the alternate solution is to stabilize the existing weak soil to meet out the design requirement. There are so many stabilizers available in the market, to overcome this problem. Now a day, nontraditional soil stabilizer called bioenzyme is emerging in the market, which is nontoxic, biodegradable and ecofriendly. In this investigation, attempt had made to study the stabilization of black cotton soil by using bioenzyme with dosages like 0, 50, 100, 150, 200 and 250 ml/m3 of soil and bioenzyme with 20% of stone aggregates (passing from 6.3 mm and retained on 4.75 mm sieve) are used. Unconfined compressive strength UCS test with different curing periods and California bearing ratio test CBR for unsoaked and soaked conditions was carried out to study the change in strength parameter and to study the reduction in swelling parameter of soil, Free swell index (FSI) was conducted. The experimental results show the increased UCS value from 170 to 435 and 553 kPa for 28 days curing. CBR results are increased from 1.2% to 2.4 and 5.4 for soaked CBR and 4.5 and 8.5% unsoaked CBR. Free swell index (FSI) decreased from 130 to 65%. © 2021, Springer Nature Singapore Pte Ltd.