This study is aimed at investigating the effects of three different additives - Sawdust Ash (SDA), Palm Kernel Shell Ash (PKSA) and Groundnut Shell Ash (GSA) on the geotechnical properties of Ido- Ekiti soil in Ido-Osi Local Government Area (LGA) of Ekiti State. Soil samples collected from the study area were subjected to various laboratory tests (i.e. Grain Size Analysis, Atterberg Limits and Compaction tests) in its treated and untreated state. The additives were added to the soil sample at different percentage - 2%, 4%, 6% and 8%. The results of the tests carried out on the untreated soil sample indicated that the soil could be generally classified as Granular soil material and is Silty or Clayey Gravel and Sand with general Subgrade rating of Excellent to good. The soil samples belong to A-2-4 group and slightly plastic. Though treatment of the soil with additives did not change its configuration, GSA additive followed by PKSA additive improved on it. GSA encourages effective compaction as there is need for more moisture contents with increasing Maximum Dry Density (MDD). Whereas reverse is the cases of PKSA and SDA, though PKSA is better than SDA. GSA is adjudged to be the best additive applied on the soil with best result(s) followed by PKSA and then SDA. Further research work needs be done on this study in other to ascertain any other suitable hidden properties of the additives.
