Evaluation of the effects of enzyme-based liquid chemical stabilizers on subgrade soils

Abstract

Paper presented at the 28th Annual Southern African Transport Conference 6 - 9 July 2009 "Sustainable Transport", CSIR International Convention Centre, Pretoria, South Africa.

The purpose of this study was to assess the strength of enzyme treated soil material. Thus the aim of the paper is to present laboratory results on the effects of two enzyme-based liquid chemicals as soil stabilizers. Soil samples were prepared for standard geotechnical tests from two types of soils treated with the two enzyme-based products. One soil had a plasticity index of 35 and the other had a plasticity index of 7. The maximum plasticity index reduction after treatment of both soils was less than 5 % and therefore not significant. A slight improvement in the maximum dry density was obtained following treatment by one product on one of the soil samples. Unconfined compressive strength was evaluated after the samples were left to cure in plastic bags for 7, 14 and 28 days and revealed a mixed effect on strength. Those instances where there was increase in strength it was less than 50 % with increase in concentration level of the two enzyme-based stabilizers and age for both soils after treatment. More independent investigations on the effects of enzymes based liquid stabilisers on the strength of treated soils are required if the level of their acceptance in road construction is to be enhanced.