Physico-mechanical and thermal properties of vibrating and self-compacting sand concrete based on recycled aggregate from concrete

Abstract

This study explores the use of recycled aggregates (RA) from concrete, replacing 100% of Cruched Sand (CS) by volume. It focuses on their processing methods and their performance compared to Self-Compacting Sand Concrete (SCSC) and Vibrated Concrete (VC). Fresh properties, including workability, are affected by RA, but RA-based SCSC meets standards. While RA-based SCSC initially had lower strength than CS-based SCSC, it improved after 28 days, yielding similar mechanical properties. RA use led to lower density compared to CS in concrete. Thermal conductivity was insulating, slightly lower in RA-based SCSC. Porosity decreased with age in all mixtures, with RA-based concrete having initial higher porosity and capillary absorption. Microstructure showed finer crystal growth in RA-based concrete. RA in SCSC exhibit a superior Interfacial Transition Zone (ITZ) compared to CS concrete, enhancing homogeneity and durability. This research supports sustainable RA use in concrete, that contingent on precise mix design and method processing of waste concretes, as well-designed SCSC. RA in construction provide scalable and economic benefits, including cost savings, infrastructure investment, sustainability, and market expansion. This contributes to the provision of environmentally friendly building materials and the sustainability of the industry.