Performance of Alkali-Activated Concrete using Municipal Waste Incinerator Bottom Ash as a Partial Replacement of Precursor at Elevated Temperatures

Abstract

Cement production is one of the world's biggest sources of CO₂ emissions, thus the development of green options like the Alkali-Activated Concrete (AAC). Recently, MIBA is considered as more environmentally friendly material to be used in concrete pavement, but the effects of MIBA on the mechanical and thermal performance of AAC, still have been poorly investigated. That is why the purpose of this study is to assess the applicability of MIBA for partial replacement of FA in AAC while considering the sustainability performance. In this work, MIBA was processed and then analyzed by X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). Concrete samples were prepared by replacing FA with 5–20% MIBA by weight, activated using a 12M sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) solution in a 1:2 ratio. The samples were then left to cure at 60°C for 72 hours and then at ambient temperature for 28 days. Compression test was conducted in addition to SEM and LCA to establish the mechanical performance of the materials and their life cycle impacts, respectively. The findings revealed that the condition of 10% MIBA resulted in the highest performance with slightly less compressive strength from the control. Up to 10% replacement led to insignificant strength loss but higher concentration caused strength and elastic modulus to decrease because of the failure of C-S-H and N-A S-H gel network. Thermal stability of prepared material was observed up to 400°C and beyond 600°C due to phase decomposition. LCA showed that the impacts of Terrestrial Acidification Potential (TAP) and Marine Eutrophication Potential (MEP) were reduced by 60%, while Global Warming Potential (GWP) and water use were stable until MIBA xvi has been processed at high energy. The present work proves that MIBA can be employed in AAC for construction purposes as a sustainable material, mainly for structures with medium thermal resistance, and aligns with the principles of a circular economy.