Application of biochar produced through co-pyrolysis of oily sludge and agricultural waste in cement-based materials.

This study explored the use of biochars derived from the co-pyrolysis of oily sludge and agricultural wastes as partial cement replacements in mortar. To evaluate the effect of mixed-feedstock biochars on cement mortar, oily sludge was co-pyrolyzed with rice husk, wheat straw, or corn core at 500°C and a 1:1 mass ratio, producing RHB, WSB, and CHB. respectively. The physicochemical properties of the biochars were characterized by SEM, XRD, FTIR, XRF, and proximate analysis. Mortars containing 1%, 3%, 5%, and 8% biochar were then evaluated for strength, water absorption, porosity, setting time, and microstructure. Compared with Common cement mortar, CHB and RHB showed better physicochemical properties and more effectively improved mortar performance. The addition of 1% RHB, 1% CHB, and 3% WSB increased compressive strength by 8.2%, 15.2%, and 4.0%. The study also revealed changes in key mortar properties, including porosity, water absorption, and setting time. Overall, biochar derived from the co-pyrolysis of oily sludge and agricultural wastes significantly enhanced the mechanical properties of cement-based composites, demonstrating its potential for application in cementitious materials.