Highway Research Record

VI. RESEARCH WORK DONE IN ACADEMIC INSTITUTIONS RELATED TO THESIS WORK
B. PAVEMENT ENGINEERING AND PAVING MATERIALS
Studies on Stabilization of Subgrade Using Bio-Enzyme and other Conventional Stabilizers

Date of Start:August 2004
Indian Institute of Technology Madras (R, C)

Scope and Objective
(i) To study the stabilization process in improving subgrade using bio-enzyme and other conventional stabilizers.
(ii) To study the soil improving characteristics of bio-enzyme stabilizer and other conventional stabilizers and their economy. The      bio-enzyme stabilizer used is “Terrazyme”, a liquid stabilizer.

Methodology
To achieve this the following methodology is followed
(i) The optimal dosage of Terrazyme worked out at which maximum CBR is obtained.
(ii) The suitable soil in which Terrazyme’s performance is in higher percentage.
(iii) Performance of various stabilizers in the soil, which is found as a suitable one for Terrazyme stabilization.
(iv) Finally based on the test results an economic evaluation is done.

Laboratory Investigation:
Laboratory Tests were carried out in three phases:
Phase I One type of soil is taken and its engineering properties were determined. Then Terrazyme is added to the soil in various quantities and determined the concentration, at which it gives the maximum CBR.
Phase II Various soil types (Five samples) were taken. For all samples, engineering properties were determined. Then the Terrazyme was added and the CBR improvement was observed.
Phase III In the first said type of soil, various stabilizers like lime and cement are added in different percentages and the improvement in CBR is determined.

Findings and Conclusions

Based on the observations the following conclusions were made:
(i) Performance of Terrazyme stabilizers is satisfactory.
(ii) Performance of Terrazyme with clayey soil is better than that of silty and sandy soil.
(iii) Though the CBR improvement in clayey soil using Terrazyme is lesser than that of other conventional stabilizers and cost is      also on higher side, the new approach of bio-enzyme design shows considerable savings in pavement thickness and cost.
(iv) Terrazyme is an economical and environment friendly stabilizer.