Evaluating the mechanical performance and durability of cement mortars incorporating sesame shells as partial cement and sand replacement

This study examines the mechanical and durability behaviors of cement mortar containing sesame shells (SS) as partial substitutes of cement and sand with regard to sustainable construction using an agricultural by-product. Three types of SS—raw powder, vinegar-treated powder and vinegar-thermal-treated powder (250 °C)—were used as the fine aggregate replacements at 1%, 2%, and 3% by weight. Mechanical performances (compressive strength, dry density) and durability (UPV, water absorption, water porosity, workability) of the composites were investigated in a systematic manner. Results show that substituting sand with SS causes a significant decrease in the compressive strength (up to 54% at 3%of replacement) and the increase in porosity and water absorption that compromised the durability. On the contrary, the use of SS, particularly the treated one, caused strength decrease (up to 42.3%) with improved durability properties specifically lower porosity (8.84%) and lower water absorption (1.7%). UPV of all mixes were above 4.2 km/s representing good internal consistency. Error bars were included in all test figures with replicate specimens to properly demonstrate the variation and to reinforce the reliability of the data. The findings suggest that the optimal use of SS is as a 3% cement replacement in treated form, offering an environmentally friendly alternative with acceptable mechanical performance and significantly improved durability.