Abstract

Stabilization of soils is an effective method for improvement of soil properties and the pavement system performance. A study was conducted to examine the stabilizing effects of an enzyme and lime on improving the suitability of a natural soft clay as a subgrade material. The tests were carried out by introducing the additives into the soil in two different stages. The enzyme and lime were first mixed individually- Soil Lime mixtures and Soil Enzyme mixtures and later concurrently- Soil Enzymatic Lime mixtures. The initial part of the study determined the variation of index properties of the three soil combination. Laboratory tests were performed with different percentages of the additives on the soil and the modification of Atterberg Limits, Grain Sizes Distribution and Free Swell Index in the soil mixtures was studied week after week for a month. From the result of the plasticity indexes obtained, satisfactory values were noted and the respective dosages were chosen as the optimum. The latter part of the study examined the optimum dosages of enzyme, lime and enzymatic-lime that produced maximum strength improvement on the treated soil. The strength criteria were investigated by conducting unconfined compressive tests on 3.8mm diameter cylindrical specimens of samples cured with the dosages at and near the optimum combinations. The effect of density and moisture content was predominant in all cases and this enabled to identify the maximum dry density (MDD) and optimum moisture content (OMC) for the mixes. It was found that enzymaticlime stabilized soils gave speedy stabilization as compared to enzyme stabilized and lime stabilized soils. The paper discusses the results obtained throughout the study. Under standard conditions, satisfactory reasons are found stating that Enzymatic Lime is a possible economical and innovative methodology for soil stabilization.