Desulfurized Gypsum/Alkali-activated Slag-PMA Lightweight Fireproof Mortar: Impact of ASP Content on Microstructure and Performance

Abstract

Slag and PMA were used as precursors, while Ca(OH)₂ and Na₂CO₃ were used as the alkaline activator. The impact of alkali-activated slag-PMA (ASP) content, defined as the mass ratio of ASP to the total of ASP and desulfurized gypsum (0, 10%, 20%, 30%, and 40%), on the drying time, setting time, dry density, fire resistance, compressive strength, bond strengths (W₀), and wind suction & vibration resistance (W_a) was explored. The underlying mechanism was revealed by XRD, TG-DTG, SEM and MIP. The experimental results indicate that, as ASP content rises, the drying time, initial setting time and final setting time are shortened, and the fire resistance of DAF first decreases and then increases, being worst at 30%. As ASP content increases, the compressive strength, W₀ and W_a first go up then drop, peaking at 20%. When ASP content increases from 0 to 20%, the hydration products increase and large pore reduce, thus increasing W₀ and W_a. When ASP content increases from 20% to 40%, the hydration products decrease, and the higher ASP content results in more internal cracks, causing to a decrease in W₀ and W_a. The research findings will promote the application of PMA in DAF.

Keywords

desulfurized gypsum/alkali-activated slag-PMA lightweight fireproof mortar / powdery municipal solid waste incineration bottom ash / alkali-activated slag-PMA content / bond strength / wind suction & vibration resistance

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