Strength characterisation of fiber reinforced expansive subgrade soil stabilized with alkali activated binder

Abstract

Expansive soil subgrade exhibits low volumetric stability due to moisture imbalance, rendering pavement serviceability loss. In the present study, an effort is made to improve the subgrade strength behavior of expansive soils by combining it with alkali activated binder (AAB) with chemically treated coir (TCF) and hemp fiber (THF). The research also compares the effectiveness of TCF and THF reinforced AAB soil by conducting a series of subgrade strength indicator tests at different slag/fly ash ratio (SFR). The influences of varying dosages of fibers and SFR in both fiber-reinforced AAB treated soil showed a significant improvement in CBR, tensile strength ratio, and flexural strength properties. It is observed that THF-AAB-soil shows higher interfacial bonding with strong interlocking density and tensile cracking resistance compared to TCF. Non-linear regression equations for CBR tests are proposed for both fibers reinforced AAB treated soil, which is chosen as a subgrade strength performance indicator. Experimental and model-predicted results of fiber-AAB-soil mixture show a satisfactory trend for low volume roads.