Enhancing the Performance of Recycled Aggregate Concrete: A Review on the Role of Fly Ash and GGBFS

Abstract

This study reviews recent research on the properties of Recycled Aggregate Concrete (RAC) and the incorporation of supplementary materials such as fly ash (FA) and ground granulated blast furnace slag (GGBFS) to improve its performance. The microstructure of RAC is more complex than that of traditional concrete, resulting in reduced mechanical properties and durability, especially at higher levels of recycled aggregate (RA). Studies reveal that contamination in RA and increased porosity negatively impact durability, particularly in chloride-rich environments. Fly ash has been effective in mitigating some of these drawbacks by improving pore structure and reducing chloride penetration, with optimal replacement levels around 25-35%. GGBFS shows similar benefits, with strength enhancements up to 55% replacement levels. The integration of RA, FA, and GGBFS can produce durable and sustainable concrete, provided that optimal replacement levels are observed. The findings highlight the potential of using recycled materials in concrete, promoting sustainability in construction.