Effect of alkali-treated sisal fibres on expansive clay

In this study, the synergic effects of alkaline activation (AA) and fibre inclusions on the mechanical behaviour of fly-ash-stabilised black cotton soil were investigated. The natural fibre used in this research was treated with sodium hydroxide solution as an expedient solution to attain durability. The fibres are added in two forms: discrete fibre and geotextile. Assessment of engineering behaviour of the AA-treated soil reinforced with surface-coated sisal fibres was carried out by conducting various laboratory tests such as free swell  test, unconfined compressive strength  test and cyclic triaxial test. Microstructural characterisation was carried out by scanning electron microscopy  analysis and Fourier transform infrared  spectroscopy analysis. The test results conclusively showed that the alkaline-activated fly-ash-treated sisal fibre-reinforced soil exhibits better mechanical behaviour in terms of peak stress and post-peak behaviour and appreciable resistance to swelling. Overall, the study shows that amendment of fibre-reinforced AA-fly-ash could effectively enhance the strength, stiffness and toughness of the soil and could subsidise the anticipated detrimental effects that could cause by dynamic loading. This study affirms the potential of alkali-treated sisal fibre to be an alternative to traditional stabilisers used in construction involving expansive soil.