Alkali-Activated Binder of Municipal Solid Waste Incineration Bottom Ash at Lower pH Levels

This paper focuses on the alkaline activation of municipal waste incineration (MSWI) bottom ash to create a dense, non-porous composite structure. Normally, high pH solutions are used to activate MSWI bottom ash, but this has the side effect of creating residual effects in the bottom ash. Due to the uniqueness of the incineration process, the bottom ash retains metallic aluminum, which reacts with the alkali to produce hydrogen gas, which forms a porous structure in the sample during the hardening of the composite. This study demonstrates a method of eliminating this effect by lowering the pH of the alkaline activator below 12.5. An alkali-activated binder was prepared from ground MSWI bottom ash as a precursor and a triple alkali activator: NaOH solution, soluble glass (SG) and silica gel waste (SW). The highest compressive strengths of about 20 MPa were achieved for alkali-activated MSWI bottom ash with triple alkali activators such as sodium hydroxide, soluble glass and silica gel waste.