Optimizing M40 Sustainable Concrete Using Wood Ash, Fly Ash, and M-Sand: A Circular Economy Approach

This study investigates the development and performance evaluation of ternary blended concrete incorporating wood ash (1–5%) and fly ash (30%) as partial replacements for cement, combined with manufactured sand (M-Sand) as a sustainable fine aggregate in M40 grade concrete. The pozzolanic properties of wood ash and fly ash facilitate enhanced the cement hydration reactions, contributing to improved microstructural densification and strength development. Comprehensive compressive strength testing at 7, 21, and 28 days revealed that an optimal wood ash replacement level of approximately 2% achieves the highest mechanical performance, demonstrating superior strength gain and durability characteristics. However, incremental increases beyond this optimal percentage adversely affect workability and reduce compressive strength, primarily due to decreased cementitious content and increased pore volume leading to diminished bonding efficiency. These results underscore the critical balance required in mix design to harness the benefits of industrial by-products while maintaining structural integrity. The research validates the feasibility of utilizing agro-industrial wastes such as wood ash alongside fly ash and M-Sand to produce eco-efficient concrete, contributing to waste valorisation, reduction of carbon footprint, and promoting sustainable construction practices aligned with environmental stewardship and resource conservation objectives.