Circular Economy in Bricks: Resource, Water, and Energy Savings via Refinery Oily Sludge

Abstract Clay brick production is a resource and energy intensive process, relying heavily on virgin clay, process water, and high firing temperatures. This study investigates the valorization of refinery oily sludge (ROS), a hazardous by-product of petroleum refining, as a partial substitute for clay in brick manufacturing. Laboratory-scale experiments incorporated 0, 5, and 10 wt.% ROS into clay mixtures, followed by extrusion, drying, and firing at 950oC and 1050oC. The results demonstrated substantial improvements in resource efficiency. Brick yield rose from 5.6 to 9.5 units/kg clay, while water demand decreased by up to 25% due to the sludge’s inherent moisture. Energy consumption during firing was reduced by more than 30% at higher sludge contents, attributed to the calorific contribution of ROS. Although color changes, efflorescence, and stratification were observed, mechanical integrity remained unaffected. The optimum performance was achieved at 5 wt.% ROS, balancing energy savings with material stability. This work provides the first experimental evidence of simultaneous reductions in clay, water, and energy consumption through ROS incorporation, demonstrating its dual role as a raw material substitute and auxiliary fuel. The findings highlight the potential of ROS valorization to support circular economy strategies and enhance the sustainability of the ceramic industry.