Abstract
As concrete production accounts for a large percentage of worldwide CO(2) emissions, there is a need for alternative sustainable construction materials. Simultaneously, the increasing generation of construction and demolition waste has led to the growing interest in using recycled aggregates (RA) in concrete. However, recycling aggregate (RAC) tends to demonstrate poor mechanical and durability performance because of relatively high porosity and weak interfacial transition zone existing in RA. This study explores the synergistic effects of coconut fiber (CF), wheat straw ash (WSA) and silica fume (SF) in its enhancement of RAC performance. Mechanical (compressive and tensile strengths) and durability (water absorption and acid resistance) characteristics of RA (50%, 75%, and 100%) incorporated with various proportions of WSA (5%, 10%, and 15%) have been studied. Additionally, CF (1.5%) and SF (7%) were also added in all mixtures. The findings show that the optimum mix (10% WSA and 50% RA) achieves a compressive strength of 30.7 MPa at 90 days. The tensile strength was also improved, with the 10% WSA mix offering the highest tensile strength of 3.89 MPa at 90 days. Durability tests showed that water absorption decreased, and acid resistance improved with the addition of WSA, especially with 10% WSA, which had the lowest water absorption of 4.8%. Microstructural Analysis of the concrete matrix showed, particularly for mixes with increased WSA content, indicate lower porosity and better bonding. The present work establishes base evidence for the use of CF, WSA and SF in improving the performance and sustainability of RAC and is a viable option for construction applications, particularly in the presence of the high construction and demolition waste regions.