The growing demand for construction materials has accelerated the depletion of natural aggregates (NAs) while simultaneously increasing the generation of construction and demolition (C&D) waste and fly ash (FA). In response, this study investigates the development of eco-efficient load-bearing solid masonry blocks (SMBs) manufactured using 100% replacement of NAs with recycled concrete aggregates (RCAs), combined with the use of FA as a fine filler. This approach remains underexplored in masonry applications. FA was introduced by replacing 30% of fine recycled concrete aggregates (FRCAs), and its influence was examined for cement-to-aggregate (C: A) ratios of 1:18 F, 1:21 F, and 1:24 F. A comprehensive experimental program was conducted to evaluate the physical, mechanical, thermal, shrinkage and sustainability performance of the developed SMBs, enabling a holistic assessment of their structural behavior and environmental viability. The incorporation of FA enhanced microstructural densification, resulting in enhanced compressive and flexural strength, lower water absorption, and reduced drying shrinkage. Although thermal conductivity increased due to the denser matrix, the blocks exhibited adequate thermal stability when exposed to moderate temperatures. From an environmental and economic standpoint, the FA-modified SMBs exhibited notable reductions in embodied carbon and production cost compared to conventional NA-based masonry units. Overall, the findings demonstrate that SMBs developed with 100% RCAs and FA filler can satisfy the performance requirements of load-bearing masonry while offering a practical, low-carbon, and cost-efficient alternative for sustainable construction.
Dafedar et al. (Sun,) studied this question.