Effect of enzymes on plasticity and strength characteristics of an earthen construction material

In this study, a commercially available enzyme which is used popularly to improve sub-grade material for pavements was used as a potential stabilizer to improve soil properties used for earthen construction. As a preliminary study, the interaction of this enzyme with the soil was assessed by evaluating the plasticity and strength characteristics of enzyme treated soil with ageing. From the research findings, it was observed that with ageing, the liquid limit of soil decreased, while plastic and shrinkage limits increased, leading to reduced plasticity and shrinkage indices. The reduced plasticity and shrinkage indices indicate that soil has become relatively more volumetrically stable and less susceptible to crack formation. Further, strength characteristics under two different curing conditions were evaluated, and it was found that under sealed curing conditions, the treated soil had better compressive strength. The improvement of plasticity, shrinkage and strength characteristics due to the addition of enzymes can be advantageously used for development of lightly stabilized durable earthen construction material, and thus, eliminating the necessity of using conventional energy-intensive stabilizers. The findings from this study bring the immense potential of eco-friendly enzymatic stabilization in the development of modern sustainable earthen materials.