Development of sustainable construction aggregates: Preparation and environmental safety assessment of sintered...

This study prepared red mud-based sintered artificial lightweight aggregates (RM-S-LWA) using red mud (RM), red brick powder (RB), soda residue (SR), and mineral powder (MP). By investigating the effects of different sintering temperatures on the physical properties, microstructure, and durability of RM-S-LWA, the optimal sintering temperature was determined, and the ceramic-forming mechanism of RM-S-LWA was explored. Additionally, this study established an assessment model for heavy metal environmental risks and human health risks to comprehensively evaluate the heavy metal release of RM-S-LWA. The results showed that the optimal sintering temperature for RM-S-LWA samples was 1050 °C. Under this condition, the cylinder crush strength, softening coefficient, apparent density, and bulk density of the prepared samples reached the highest values (11.6 MPa, 0.98, 1256 kg/m³, and 1089 kg/m³), while the water absorption rate and void ratio reached the lowest values (6.2 % and 13.3 %), all of which met the requirements of the Chinese standard "GB/T 17431.1-2010". Findings from the human health risk assessment showed analysis indicated that although hand-to-mouth ingestion represented served as the primary dominant exposure pathway route for non-carcinogenic risks impacts of heavy metals in RM-S-LWA. However, the non-carcinogenic risks to for both adults and children and adults were negligible. Sintered lightweight aggregates are expected to be applied in bridges, building reinforcement, and low-carbon building material substitution, reducing construction and maintenance costs, providing technical support for the green upgrading of civil engineering, and integrating significant sustainability and application value.