Potential Application of Oil Shale Ash and Silica Fume Grout in Structural Systems: a Sustainable Approach

Abstract

This experimental investigation has aimed to evaluate the mechanical and the durability properties of Oil Shale Ash (OSA) and Silica Fume (SF) grouts and assess their potential use in various engineering applications with the goal of improving sustainability. OSA-blended cement grouts have been prepared at water-to-cement ratios of 0.5 and 0.6, with OSA replacing cement by 5%, 10%, 15%, and 20%, and some mixtures have included 2.5% SF. By following ASTM standards, OSA-blended cubic and prismatic cement specimens have been tested and compared with plain cement specimens cured at different durations. Results have indicated that as OSA replacement level has increased to 20%, the compressive strength of grout has decreased by 11%. However, flexural strength results have remained relatively consistent. With higher OSA replacement levels, drying shrinkage has increased by 116%, while sulfate expansion has decreased by 33%. The exposure of cement grout to 200 freeze-thaw cycles had a minor impact on strength, with residual compressive strength values ranging between 89% and 95%. Overall, OSA-blended cement grout has met the minimum mechanical and durability requirements, making it suitable for both nonstructural and structural engineering applications. Recycling OSA in cement grout is an attractive approach to reduce environmental pollution, as it minimizes stockpiling or dumping of this hazardous material in limited landfills.