Reuse of Pretreated Red Mud and Phosphogypsum as Supplementary Cementitious Material

Abstract

The combination of red mud (RM) and phosphogypsum (PG) can exert the alkalinity of RM and the acidity of PG as a calcium source to promote the gel hardening of composite cementitious material, which effectively improves the reutilization efficiency of RM and. In this study, the effects of the ratio and content of pretreated RM and PG on the non-evaporated water, porosity, hydration products, mechanical properties, pore size distribution, and microstructure of composite cementitious materials were investigated. The results show that, with the incorporation of PG, RM, PG, and RM, the non-evaporable water content, reaction degree, compressive strength, and flexural strength show a downward trend after rising first, and their values reach the maximum with 10% PG and 10% RM, which are higher than a pure cement system, while 70% PG, 70% RM, 70% RM + 10% PG, and 70% PG + 10% RM have the reverse effect. The results of hydration products, pore size distributions, and microstructure indicate that adding an appropriate dosage of RM and PG can efficaciously improve the compactness of cement systems. Nevertheless, the research results can contribute to using the combination of PG and RM to manufacture sustainable cementitious materials with good performance, and achieve the purpose of environmental protection and industrial solid waste resource recycling.

Effects of Pretreated Phosphogypsum and Granulated Blast-Furnace Slag on the Rheological Properties of the Paste Excited by NaOH

“…In addition, because its chemical composition is similar to that of natural gypsum, PG can replace some natural gypsum to produce cement retarder [ 17 ]. In recent years, scholars have found that PG contains a great deal of minerals such as SO 3 , CaO, SiO 2 , etc., which are similar to the chemical composition of cement and can replace part of cement as a cementitious material [ 18 ]. It is important to improve the working performance of PG-based cementitious materials, which can be compounded by a certain amount of admixtures, such as granulated blast-furnace slag [ 19 ], fly ash [ 20 ], silica fume [ 21 ], steel slag [ 22 ], and other common admixtures, to achieve a comprehensive use of PG.…”

Investigation of the performance of cement mortar incorporating lithium slag as a super-fine aggregate

“…Few studies have examined the technology of the use and recovery of lithium slag. Exploring uses of lithium slag is beneficial to the sustainable development of lithium salt industry, saves natural resources, and protects the environment (Li et al, 2021;Dong et al, 2023).…”