Effect of incorporating multifilament polypropylene fibers into alkaline activated fly ash soil mixtures

Abstract

Soil stabilization is a well-known methods for the treatment problematic soils. Its advantages over soil replacement include low cost and fast implementation. The alkaline activation of soft soils is a new technique that has been proposed recently to stabilize soft soils. However, its strengthening mechanism and the final product in terms of stiffness and brittleness resemble those observed in cemented soils. In other words, the residual strength which emerges when approaching failure is very low, and this results in immediate damage to building structures. These shortcomings need to be overcome, particularly in places where seismic loading can be expected. In the case of cemented columns under heavy embankments, horizontal displacement is likely to occur under seismic loading. This will result in the failure of stabilized material due to frail bending moments, making greater residual strengths more important than higher peak strengths. To address this problem, a fix fly ash content of 40% and polypropylene fibers in the range of 0.5%, 0.75%, 1%, and 1.25% were considered. Compressive, flexural and indirect tensile strength test results revealed the feasibility of polypropylene fibers to improve post-peak behavior, thus allowing for higher residual strength after failure.