Thermal Treatment on MSWI Bottom Ash for the Utilisation in Alkali Activated Materials

At present, most municipal solid waste incineration (MSWI) bottom ash is directly landfilled, raising concerns about environmental issues and loss of resources. Due to its high mineral content, MSWI bottom ash is now being considered as a raw material to prepare alkali-activated materials (AAMs). However, the mineral fraction unavoidably contains metallic aluminium (Al) and zinc (Zn) scraps (<1 wt.%), which easily oxidise and generate H2gas under alkaline conditions. As a result, when using MSWI bottom ash to prepare AAMs, the formation of a porous structure, as well as expansive cracks (both detrimental to strength development) can be observed. In this research, thermal treatment of MSWI bottom ash, at temperatures of 500 and 1000 °C, was performed to deal with the issue caused by metallic Al/Zn. A series of tests, including Quantitative X-ray diffraction (QXRD) analysis, fineness measurements (particle size and surface area), and the dissolution test, were conducted to examine the effects of thermal treatment on as-received bottom ash. The results indicate that it is difficult to oxidise metallic Al/Zn at 500°C, but heating up to 1000 °C can realize the complete oxidation of Al/Zn, which in turn allows the wide utilisation of bottom ash in AAMs. Keywords: MSWI bottom ash, thermal treatment, alkali-activated materials

Utilization of biomass fly ash in alkali-activated materials

This paper investigated the feasibility of using biomass fly ash (BFA) to prepare alkaliactivated slag and fly ash paste. The reference mixture was alkali-activated slag and coal fly ash (CFA) paste with a slag-to-coal fly ash ratio of 50/50. In other mixtures, coal fly ash was replaced at 40% and 100% with BFA, respectively. The results showed that the incorporation of BFA accelerated the setting of the paste, while its impact on the compressive strength was minor. XRD and FTIR results indicated that the BFA participated in the reaction process. BFA showed potential use as CFA replacement in synthesizing alkali-activated materials, which would pave a way for the valorisation of BFA

Utilization of biomass fly ash in alkali-activated materials

This paper investigated the feasibility of using biomass fly ash (BFA) to prepare alkaliactivated slag and fly ash paste. The reference mixture was alkali-activated slag and coal fly ash (CFA) paste with a slag-to-coal fly ash ratio of 50/50. In other mixtures, coal fly ash was replaced at 40% and 100% with BFA, respectively. The results showed that the incorporation of BFA accelerated the setting of the paste, while its impact on the compressive strength was minor. XRD and FTIR results indicated that the BFA participated in the reaction process. BFA showed potential use as CFA replacement in synthesizing alkali-activated materials, which would pave a way for the valorisation of BFA.Materials and Environmen

Reactivity and leaching potential of municipal solid waste incineration (MSWI) bottom ash as supplementary cementitious material and precursor for alkali-activated materials

This work evaluated the reactivity and leaching potential of municipal solid waste incineration (MSWI) bottom ash as supplementary cementitious material (SCM) and precursor for alkali-activated materials (AAM). The chemical composition of the amorphous phase in MSWI bottom ash was found to be in the same range as that of Class F coal fly ash. The reactivity of MSWI bottom ash as SCM and AAM precursor was tested to be much lower than that of blast furnace slag, but similar to that of Class F coal fly ash. The method of thermodynamic modeling was found useful in providing references for the mix design of MSWI bottom ash-based AAM. Grinding MSWI bottom ash into powder for the application of SCM and AAM precursor increased its leaching potential. Based on the findings of this study, recommendations were provided on how to use MSWI bottom ash to prepare blended cement pastes and AAM.Materials and EnvironmentDC systems, Energy conversion & Storag