Improvement of Geotechnical Properties of Kaolin Clay using a Combination of Palm Oil Fuel Ash (POFA), Eggshell Waste, Guar Gum: A Preliminary Study

Abstract

Clay soils with high plasticity and water content present significant challenges in construction due to low bearing capacity and instability. Conventional binders like cement and lime, while effective, raise environmental concerns and may underperform in certain soil types. This study investigates the use of sustainable soil binders derived from agricultural and industrial wastes, namely Palm Oil Fuel Ash (POFA), Eggshell Powder (ESP), Calcined Eggshell (CES), and Guar Gum (GG), to improve the geotechnical properties of problematic soils. The research aims to address the environmental drawbacks of traditional binders by evaluating the efficacy of three binder combinations: POFA with ESP, POFA with CES, and POFA with CES plus GG, in enhancing the strength of Kaolin Clay. Laboratory tests assessed unconfined compressive strength (UCS) across various dosages and curing periods. Results revealed that the POFA-CES combination significantly outperformed others, achieving the highest UCS values, while Guar Gum addition had minimal impact on strength but altered binder behaviour. Optimal results were obtained at a 30% binder dosage with a 14-day curing period. The findings suggest that POFA and CES mixtures offer a sustainable, effective alternative to conventional binders, reducing environmental impact and promoting the use of local waste materials. These binders are viable for improving soil stability in road subgrades and other geotechnical applications, supporting eco-friendly construction practices.