Laboratory tests were conducted to assess the effect of compactive effort on the desiccation-induced volumetric shrinkage strain of compacted waste foundry sand treated with up to 8% bagasse ash (a
pozzolana) by dry weight of foundry sand for use as a hydraulic barrier material in waste containment applications. The compative energy levels of reduced British standard light (RBSL), British standard light (BSL), West African standard or ‘intermediate’ (WAS) and British standard heavy (BSH) efforts were utilized at molding water contents of 2% dry of optimum, 0% optimum moisture content and 2% and 4% wet of optimum. A compaction plane of acceptable values for volumetric shrinkage strain (VSS) based on the regulatory value ≤ 4% was used to assess the effect of compactive effort on desiccation-induced shrinkage of bagasse ash treated foundry sand. Higher compactive effort generally recorded less volumetric shrinkage strain values. Generally, VSS values increased with higher molding water content and increased with higher initial degree of saturation for all compactive efforts. However, at 6% and 8% bagasse ash treatment levels, higher compactive effort, did not result in lower VSS values, especially at WAS and BSH compactive efforts. This can be attributed to the lack of sufficient water at higher compactive efforts to meet the hydration demands at higher treatment levels.