The overuse of natural aggregates for construction causes many environmental problems. In light of their environmental impact, the discussion has increasingly focused on using alternative plant-based materials and processes such as oil palm shells (OPS). However, previous studies show that OPS have a weak adhesion with cement paste, which results in a decrease in the physical and mechanical properties of OPS concretes. One of the solutions for this problem is to carry out a surface treatment on OPS before using them in concrete. This study has examined the influence of five treatments on the physical and mechanical properties of concrete: treatment with lime (CH), sodium silicate (SS), polyvinyl alcohol (PVA), heat treatment (TH) and OPS saturation (SAT). Lime treatment (CH) on OPS showed good improvement in the mechanical properties of concrete, compared to untreated OPS.