Geopolymer-based solidification and stabilization for environmentally sound disposal of asbestos-containing waste

Abstract

Historically the disposal of asbestos-containing wastes (ACW) poses significant environmental and health risks due to the hazardous nature of asbestos fibres. Conventional disposal methods such as landfilling without any prior treatment lack long-term sustainability and safety. In this study, we explore the application of geopolymers as a green binder for the solidification and stabilization (S/S) of asbestos-containing waste (ACW) prior to its final disposal into scientific landfill sites to mitigate environmental and health hazards. Geopolymer–asbestos blocks were developed using class F fly ash and alkaline activators. Compressive strength tests revealed that the geopolymer–asbestos blocks exhibited strengths exceeding 8 MPa, making them suitable for safe disposal in landfill facilities. The ideal asbestos content for achieving substantial compressive strength was found to be between 5 and 15% (w/w). Microstructural analysis confirmed the entrapment of asbestos fibres within the geopolymer matrix, enhancing structural integrity. XRD analysis identified quartz as the major mineral phase, with traces of other minerals. Leaching studies demonstrated effective immobilization of toxic metals, such as chromium and lead, within the geopolymeric structure. The absence of heavy metals in leachate samples indicated the efficiency of geopolymer-based S/S in preventing environmental contamination. This study suggests that geopolymerization offers a promising approach for the environmentally sound disposal of asbestos-containing wastes, providing a viable interim solution until the complete cessation of asbestos use in many countries across the globe.

Graphical abstract