Low-carbon Cement Production from Municipal Solid Waste Incineration residues

Currently, Hong Kong purely relies on landfills for disposing the city’s waste. Given that land is scarce in Hong Kong, the government is building an Integrated Waste Management Facilities (IWMF) to address this imminent waste problem in a holistic manner, and a 3000 ton/d moving grate incinerator is the most critical component of it. However, incineration is not an end of pipe MSW treatment method, as about 600 tons/d of incineration bottom ash (IBA) is expected to be generated when IWMF Phase 1 starts commissioning in 2025. How to utilize this residue becomes a new challenge. A low-carbon cement was synthesized primarily from municipal solid waste incineration (MSWI) residues at a low clinkering temperature. The resulting clinker (low-carbon cement) demonstrated latent hydraulicity when reacted with water and strong carbonation reactivity when reacted with carbon dioxide. Under carbonation curing, the binder performance was benched against control specimens prepared from ordinary Portland cement (OPC), while permanently storing considerable amount of CO2 in the paste matrix. The synthesis of low-carbon cement, and its use as a carbon-sequestering alternative binder in concrete, holds reasonable merit for consideration as an adaptable cleaner production to improve current-day MSW incineration practice.