Strength and durability assessment of expansive soil stabilized with recycled ash and natural fibers

Abstract

This study explored the coupling effect of the recycled ash and natural fibers to control the expansive soil's strength and durability attributes. The bottom ash (BA) was used to chemically treat the expansive soil and coir fibers (CF) as reinforcement against tensile cracking. The sustainable use of BA and CF to stabilize the expansive soil has been demonstrated by assessing - swelling behavior, mechanical and chemical properties. The expansive soil was stabilized with 5%, 10%, 15% and 20% BA and reinforced with 0.25%, 0.50% and 1.00% CF. The curing period of 28 days was considered for the stabilization of the soil. This study presents individual material's effect to stabilize the expansive soil subgrade and also the coupling effect of both fibers and ash. The durability of stabilized expansive soil has been assessed by investigating the mechanical and chemical properties before and after 2nd, 4th, 6th, 8th and 10th freeze–thaw cycles. The BA stabilized expansive soil exponentially reduces the upward swelling pressure and controls the plasticity behavior. An increase in the percentage of BA has increased the calcite content, pH, and electrical conductivity. The unconfined compressive strength and split tensile strength have been increased due to BA and CF. The CF reinforced specimens shows less loss in mechanical strength during freeze–thaw cycles and gives higher tensile strength. The effective mechanism of BA and CF stabilized expansive soil is discussed in detail. The BA and CF can be effectively used to stabilize the expansive soil for the application of road pavements. The approach used here to stabilize pavement subgrades is sustainable and will provide economical solutions. © 2021 Elsevier Ltd