Medical waste incineration ash (MWIA) is an increasingly important solid-waste residue, yet it is often disposed of without stabilization, creating potential environmental risks. This study evaluates the feasibility of using the MWIA investigated here as a partial cement replacement (0–40% by mass, at 10% intervals) in three concrete grades (M25, M30, and M35). MWIA was collected from the CCC incinerator under lower temperature (600–700°C), oven-dried, ground, and sieved to <75 μm. Mechanical performance was assessed using Compressive and Splitting Tensile Strengths at 7, 28, and 56 days, while durability-related properties were evaluated using Ultrasonic Pulse Velocity (UPV), Fresh Density, Water Absorption, Void Content, and Rapid Chloride Permeability Test (RCPT). Environmental safety was assessed through total heavy-metal inventory by aqua regia digestion, semi-dynamic tank leaching of stabilized mortar and pH-controlled batch leaching of raw ash and demolished mortar. XRF showed that the MWIA investigated in this study is CaO-rich (CaO 40.25%) with an oxide sum of SiO2, Al2O3 and Fe2O3 slightly below the ASTM C618 criteria for conventional pozzolans. Across all grades, 10% MWIA provided the most balanced performance: at 56 days, strength recovered to approximately 95–98% of the control mixes. The average 56-day to 28-day strength gain ratio was also highest at 10% MWIA, with a value of 1.218. UPV remained above 3500 m/s, and the RCPT charge passed decreased by approximately 4.82–14.46% relative to the OPC mixes for different grades. Replacement levels of ≥20% produced persistent strength reductions and increased porosity-related indicators. Leaching results showed that cement-based stabilization greatly reduced heavy metal release. The cumulative leached fraction remained below 2% of the total metal inventory at 10% replacement and stayed within about 3-6% even at 40% replacement. These results suggest that low-dose MWIA use can be a practical option under controlled processing and curing conditions. Microstructural confirmation of the underlying hydration and immobilization mechanisms remains a priority for future work.
Sarker et al. (Tue,) studied this question.