Mechanical and sustainability performance of concrete incorporated limestone powder, recycled ceramic aggregates, and coconut fibers

The construction industry faces significant challenges related to the environmental impact of cement production and the depletion of natural aggregates. While individual use of supplementary cementitious materials, recycled aggregates, and natural fibres in concrete has been widely studied, limited research has explored the combined incorporation of these materials and their synergistic effects on both mechanical performance and sustainability. This study investigates the integration of limestone powder as a partial cement replacement, recycled ceramic aggregates as substitutes for natural coarse aggregates, and coconut fibres as reinforcements in concrete. The objective is to enhance mechanical properties and sustainability while maintaining structural integrity and workability. An experimental program was developed to optimize mix designs with varying proportions and evaluate properties such as thermal insulation, workability, mass loss for durability, embodied carbon, water absorption, and mechanical strengths (compressive, tensile, and flexural). The results revealed that a mix containing 15% limestone powder, 30% recycled ceramic aggregates, and coconut fibres achieved optimal mechanical performance, adequate workability, and reduced embodied carbon. Although higher ceramic aggregate content slightly increased water absorption due to porosity, the mix demonstrated enhanced thermal insulation and long-term durability. These findings emphasize the novelty and potential of combining industrial by-products with natural fibres in a single concrete composite, paving the way for greener and more sustainable construction practices.