Effects of different admixtures on the working performance and mechanical properties of phosphogypsum slag-based composite cementitious materials

Abstract

Phosphogypsum slag-based composite cementitious materials were prepared by using phosphogypsum and slag powder as the main raw materials, adding quicklime, lithium slag, steel slag and other admixtures, and adding NaOH, NaHCO3 and triethanolamine (TEA). The effects of different admixtures on the fluidity, setting time and compressive strength of the composite cementitious materials were studied. Finally, XRD, MIP, TG-DTG, and SEM microscopic tests were used to analyze the reasons for the performance changes caused by the admixture from the aspects of phase composition, pore distribution, and hydration product morphology. The results show that the addition of NaOH, NaHCO3 and TEA reduces the fluidity and strength of the material and improves the setting time. The paste with 1 % NaOH and 0.03 % TEA can balance the working performance and mechanical properties.