Preparation and study of magnesium ammonium phosphate cement from waste lithium slag

Due to the recent surge in the lithium slat industry, a high amount of lithium slag (LS) is generated as industrial waste and stacked open, causing environmental pollution and occupying land resources. In this regard, this research very first time investigates the use of LS to prepare and study the physical and mechanical properties of magnesium ammonium phosphate cement (MAPC). It is believed that results will be helpful in reducing the burden of LS on the environment and in improving the construction sector sustainability. For this purpose, LS was replaced with the MAPC by 10%, 20%, 30%, 40%, and 50%. A gradual increase in LS quantity decreased the fluidity and increased the setting time of LS-MAPC mortars. Comparison of results showed that heat curing of samples at 70 °C for 24 h produced LS-MAPC mortars having high strength than the air-curing. Among all mixtures, a replacement level of 10% was found as the optimum dosage and produced the best results as compared to other mixtures. Mechanical properties of LS-MAPC mortars were improved when amount of MAPC replacement by LS was 10%. Water absorption and porosity of mortars showed a direct relationship with the percentage of LS. Reaction products were studied by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscope analysis and their findings corroborated with experimental results. •Lithium slag was used to replace the magnesium phosphate cement.•Influence of lithium slag on flowability and setting time was studied.•Air curing and heat curing methods were employed to determine the suitable curing regime.•Lithium slag improved the flexural and compressive strength at optimum dosage of 10%.•Microstructure results of cement pastes supported experimental findings.