Mechanical And Microstructural Performance of Concrete Incorporating Bio-Medical Waste Ash As A Partial Replacement of Cement

Abstract

This study examines the potential of Biomedical Waste Ash (BMWA) as a sustainable and eco-friendly partial replacement for cement in M30 grade concrete. Concrete mixes were produced with 0%, 10%, 20%, and 30% BMWA at a constant water–cement ratio of 0.45, and their fresh, mechanical, and microstructural properties were evaluated. The fresh concrete tests indicated that the slump value and overall workability decreased slightly as BMWA content increased, yet these reductions remained within acceptable limits for practical applications. Mechanical testing revealed that BMWA replacement at 10–20% provided the most significant improvement in compressive, split tensile, and flexural strength, particularly at later ages, owing to enhanced pozzolanic activity. However, higher replacement levels, such as 30%, resulted in a slight decrease in strength because of reduced cementitious material. Microstructural investigations supported these findings: SEM analysis showed effective bonding between BMWA particles and the cement paste, forming a denser and less porous matrix. Energy-dispersive spectroscopy (EDS) confirmed the presence of essential oxides responsible for pozzolanic reactions. Additionally, X-ray diffraction (XRD) analysis identified the formation of major cementitious compounds, including calcium silicate hydrate (C-S-H) and portlandite, indicating that BMWA actively participates in hydration. Overall, the study demonstrates that BMWA can serve as a viable partial replacement for cement, improving key properties of M30 concrete at optimum levels while promoting sustainable waste management and lowering environmental impact without compromising performance.