Compaction characteristics of kaolin reinforced with raw and rubberized oil palm shell

This paper presents an attempt to evaluate the suitability of oil palm shell (OPS) and rubberized OPS (ROPS), an alternative bio-material, as reinforcement in kaolin. OPS was surface coated with rubber, and its water absorption potential was studied in 5 media involving water and kaolin samples (with different water contents). The water absorption data measured in the laboratory was used as an indirect measure to verify the degradability of ROPS samples when used as reinforcements in kaolin. The surface treatment of OPS with rubber was found to perform well, with around a fivefold decrease in water absorption, thus making it an ideal treatment procedure to this end. Kaolin-ROPS mixtures with different OPS and ROPS proportions (0, 5%, 10%, 20%, and 30% by weight) were prepared in laboratory to evaluate their compaction behaviors. Both standard proctor compaction and mini-compaction procedures were adopted in this study to ensure applicability of the findings across a wide range of compaction methods adopted in the laboratory. Compaction curves obtained for both kaolin-OPS and kaolin-ROPS mixes showed a decreasing trend in the maximum dry density values with increasing proportions of OPS and ROPS. Optimum water content of kaolin-OPS mixtures did not show a significant variation, while kaolin-ROPS mixture showed a downward trend with increasing ROPS contents, thereby signifying improvement in the compaction characteristics after OPS reinforcement in kaolin.