Curing effects on geotechnical properties of clays treated with palm kernel shell ash and rice husk ash: Insights from water absorption characteristics of stabilizers

Abstract

This study aimed to address and overcome the inherent challenges associated with the influence of primary curing on the consistency, compaction, and strength attributes of clays treated with biomass ash, specifically palm kernel shell ash (PKSA) and rice husk ash (RHA), for stabilization. Primary curing refers to the time from the addition of PKSA or RHA to the clay until its use for fill or backfill purposes. This study explores the effect of curing on the water absorption capacities of PKSA and RHA to elucidate the treatment mechanisms that shape the characteristics of the treated clays. Wab, which is the amount of water absorbed by 1 g of each stabilizer, was determined using the suction filtration technique. PKSA exhibited a significant increase in Wab with an increase in the curing period t. Wab of RHA showed no significant variation with t. The water absorption mechanisms of each stabilizer were successfully demonstrated using scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns. It was also observed that the impact of primary curing on the limit states, compaction, and strength of the clays treated with PKSA and RHA differed significantly. The observed differences are consistent with the variation in Wab with respect to t between PKSA and RHA. The test results also suggest that changes in the free water content of the clays owing to water absorption by PKSA and RHA are closely related to changes in the properties of the PKSA- and RHA-treated clays. Parameter β represents the product of Wab and the addition ratio of each stabilizer, A, relative to the mass of the dry clay. The contributions of β to the limit states, compaction, and strength attributes of PKSA- and RHA-treated clays were much more significant than those of A.