Rice husk ash, Municipal Solid Incineration Ash and coal fly ash was served as aluminosilicate precursor in synthesis of one-part alkali activated geopolymer binder. These by-products industrial wastes were subjected to physio-chemical processing of materials (mechanochemical synthesis) together with different naturally originated sources of alkaline earth metal cations into one-part alkali activated (geopolymer) binder binders. The binder of hydraulic binders was assessed based on their strength development attributes and morphology with respect to silica content, diffusion of Calcium ions and compositions of Alkali activator. The particle size distribution, the chemical composition, mineralogy, bond environment, of binder particles and effective immobilization of heavy metals of hydrated binder pastes were also inspected. The results highlighted that the ternary blend of combustion ashes to produce hydraulic binders with strength development qualities and safe disposal as material for building construction.

Introduction

Large-volume use of industrial wastes for production of construction materials can divert large quantities of industrial byproducts from landfills for value-added use towards improving the sustainability and economics of infrastructure systems [1–۳]. This practice can also mitigate the release of toxic leachates to the environment by stabilizing the hazardous constituents of some industrial byproducts. The slate of fuels burned by power plants to generate electricity has been expanded beyond coal, to include biomass and municipal solid waste (among others). Combustion of these fuels generates solid residues (ash). Examples of these solid residues are coal fly ash, bottom ash resulting from combustion of municipal solid wastes, and biomass (e.g., rice husk) ash [4–۶]. These ashes largely comprise the mineral constituents of each fuel. The combustion process also concentrates any heavy metal constituents of the fuel in ash, which should be addressed in development of applications for the ash. The work reported herein develops an alternative binder chemistry using a blend of coal, biomass and municipal solid waste combustion ashes. The binder chemistry used here yields hydration products with desirable capabilities for stabilization of heavy metals.