Understanding the impacts of binary additives on the mechanical and morphological response of ameliorated soil for road infrastructures

Abstract

In an attempt to promote a cleaner environment, the deployment of waste materials in soil amendment protocols have been a major concern for civil engineers. Recent discoveries in the study of soil mechanics have revealed the pozzolanic tendencies demonstrated by these waste materials, which are beneficial in the development of road infrastructure. This has necessitated the need for this research to document the impacts of exploring the usage of combined solid waste derivatives in ameliorating the geotechnical parameters of deficient soil. The current stabilization exercise was geared towards the improvement of the mechanical properties of soil and surpassing the detrimental tendencies especially caused by seasonal variations. Moving forward, the microstructural response of the unaltered and additive ameliorated soil was investigated via qualitative means such as scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The additives including cement kiln dust (CKD) and rice husk ash (RHA), were added by air-dried weight of the soil and compacted based on the standards of British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy (BSH). With regard to the compaction exercise, incorporation of these additive materials into the soil facilitated a gradual increase in the maximum dry density (MDDs) followed by a decrease in the optimum moisture contents (OMCs). In view of these research findings, soil treatment studies facilitated a substantial upsurge in the strength (California bearing ratio (CBR) and unconfined compressive strength (UCS)) values of the ameliorated soil, in agreement with the requirements of Nigeria general specification for all compactive efforts. Finally, the usefulness and efficacy of combining these wastes in deficient soil treatment were validated qualitatively via the SEM and FTIR strategies. The results of the SEM analysis revealed some disparities between the unaltered and altered soil specimens, providing insights into the direction of calcite formation in the additive-treated soil.