The Effect of Organic Contaminants on the Microstructure-Based Mechanical and Durability Parameters of Concrete Containing Polluted Aggregate Materials

Industrial activities, particularly in petrochemical and refinery sectors, have introduced a wide range of organic pollutants into the environment, leading to the pollution of aggregate materials with crude oil or petroleum products. This study investigates the influence of aggregate materials contaminated with crude oil and diesel on the cement hydration process and concrete properties. Around 90 concrete samples with polluted aggregates were evaluated over a 6-month period. Compressive strength tests and water absorption percentage tests were conducted at different ages. Microstructural analysis through SEM, structural analysis via EDX, and XRD analysis for hydration product characterization were performed. Results showed a significant reduction in compressive strength (47% and 31%) for samples contaminated with crude oil and diesel, respectively, compared to the control. Water absorption and permeability increased in polluted samples. SEM, and XRD, results indicated increased ettringite production, decreased nanostructure C-S-H, reduced strength and durability, and increased water absorption and permeability in the concrete. This study highlights the detrimental effects of organic contaminants on concrete properties, emphasizing the need for pollution management in aggregate materials for sustainable construction practices.