| Synthesis of green cement from incinerator residues and carbonation activation Yixin Shao1; Zaid Ghouleh2; 1CIVIL ENG DEPARTMENT, MCGILL UNIVERSITY, Montreal, Canada; 2MCGILL UNIVERSITY, Montreal, Canada; PAPER: 183/Nonferrous/Regular (Oral) SCHEDULED: 18:15/Tue. 29 Nov. 2022/Arcadia 2 ABSTRACT: Municipal solid waste incineration (MSWI) is a widely implemented waste management option. Although MSWI reduces waste volume by 90%, it generates considerable incinerator residues, namely, bottom ash and fly ash – the latter posing a greater challenge on account of containing leachable heavy metals, chlorides, and organic contaminant. On the other hand, the bulk of the fly ash’s composition makes it a rich mineral source for silica and lime, and potentially well suited as a raw meal in cement production. This paper presents a study on the feasibility of making green cement using three of the incinerator by-products: incinerator heat, residue ashes and carbon dioxide. The green cement can be synthesized exclusively with incinerator residues at incinerator heat temperature of 1000°C. The cement paste is then activated by carbon dioxide to produce strength. Municipal solid waste incineration can be turned into a green cement production. Paste compacts prepared from this material displayed a high CO2 reactivity, achieving an average compressive strength of 53 MPa and an average CO2 uptake of 6.7 wt. % after only 2 hours of carbonation activation at 1.5 bar. QXRD and QEMSCAN results identified the reactive phases to be chloro-ellestadite (Ca10(SiO4)3(SO4)3Cl2) and γ-C2S, which, upon CO2 activation, formed a binding matrix comprised of gypsum, calcium-carbonate precipitates, and a Ca-Si intermix. Leaching tests deem this cement non-hazardous as the monitored heavy metal concentrations in the leachate were well below regulatory limits. Concrete specimens prepared from the cement displayed comparable performance to Portland cement concrete, while additionally demonstrating a viable approach for waste utilization, carbon emission reduction, and natural resource preservation. References: [1] Raupp-Pereira, F.; Ball, R.J.; Rocha, J.; Labrincha, J.A.; Allen, G.C. New Waste Based Clinkers: Belite and Lime Formulations. Cement and Concrete Research 38, (2008) 511-521. [2] Pellenq, R. J. M.; Lequeux, N.; Van Damme, H. Engineering the Bonding Scheme in C-S-H: The Iono-covalent Framework. Cement and Concrete Research 38, (2008) 159 – 174. [3] Batchelor, B. Overview of Waste Stabilization with Cement. Waste Management 26(7), (2006) 689-698. |
