Reusing waste red brick powder as partial mineral precursor in eco-friendly binders: Reaction kinetics, microstructure and life-cycle assessment

Abstract

A large number of solid wastes are produced in the process of demolishing old buildings, and waste red brick is one of such wastes. To discuss the reutilization of waste red brick powder (WRBP) in alkali-activated material, a novel ternary eco-friendly binder was prepared by using slag, fly ash and WRBP as precursor. The impact of WRBP on the reaction kinetics, microstructure and life-cycle assessment of alkali-activated cement paste were evaluated. The Johnson-Mehl-Avrami-Kolmogrov model was established based on the heat release results. With the incorporation of WRBP, the degree of reaction was deepened, supporting the enhancement of matrix strength. X-ray diffraction and thermogravimetric analysis results show the consistent mineralogical composition of reaction products and increase of gel quantity. Pore characteristics determined by mercury intrusion porosimetry method exhibit that large capillary pores were refined by enrichment of gels and filling effect of WRBP. From the economic and environmental aspects, the reuse of WRBP significantly saved the energy consumption and reduced the carbon dioxide (CO2) emission. On the basis of the optimal compressive strength, the energy consumption efficiency index and CO2 intensity index were 27.3 MJ/MPa and 1.7 kg/MPa, which can provide 38.55% energy consumption and 44.90% carbon footprint savings. Such work may shed valuable insights to the recycling of various types of solid waste and low-carbonation of building field.