Life cycle assessment and environmental impact of blended cementitious mortar with incinerated biomedical waste Ash as partial replacement to cement

In a sustainability-driven world, repurposing industrial byproducts into construction materials is vital for reducing environmental impact and resource conservation. Incinerated biomedical waste ash (IBWA), typically regarded as hazardous landfill waste poses significant environmental challenges. However, high calcium (∼45 %) and silicate phases in IBWA contribute to hydration and pozzolanic reaction making it a potentially sustainable cementitious material. From this perspective, this study investigates the life cycle assessment and environmental impact of blended cementitious mortar incorporated with IBWA as a partial replacement for cement, focusing on its ecological and technical benefits. A cradle-to-gate life cycle assessment (LCA) confirmed that uutilization of IBWA in cementitious mortar conserves natural resources, reduces embodied energy consumption, lowers CO 2 emissions, and minimizes eutrophication and human toxicity potential by capturing heavy metal within hydration products. To ensure environmental safety, TCLP-ICP-MS analysis was conducted, which affirms that IBWA leachate concentrations were well below EPA regulatory limits and further reduced during hydration, stabilizing heavy metals (Cr, Cu, Hg, Ni, Pb, etc.) in the solidified matrix. The optimal IBWA dosage of 10 % offered a balance between both technical performance and sustainability. The porous and non-spherical morphology of IBWA increased water demand and inter-particle friction, and its SiO₂ + CaO content (>50 %) enhanced cement hydration. Thermogravimetric analysis (TGA), Xray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analyses confirmed the progressive formation of secondary hydration products (C-S-H, and C-A-S-H), contributing to densified microstructure (Ca/Si ratio: ∼1.2). The final sustainable performance score of 0.77 for the IBWA10 mix signifies an eco-efficient and balanced formulation, offering structural integrity along with environmental and economic advantages. • Cradle-to-gate LCA showed reduced CO₂, energy use, eutrophication, and toxicity, while conserving natural resources. • Hydration and pozzolanic reactions immobilize heavy metals in C-S-H/C-A-S-H gels, ensuring long-term environmental safety. • The sustainability score of 0.77 affirmed IBWA10 as an eco-efficient, cost neutral, and structurally viable cement blend. • Ca/Si ratio is directly proportionate to permeable porosity and inversely related to quantified bound water (WH). • FTIR confirmed Si-O-T, C-O, and S-O bands, validating hydration products identified in XRD at C-S-H, CaCO 3 , and AFt phases.