Performance and hydration of ternary compound cement by using lithium slag, limestone and clinker

With the increased requirement of lithium salts in lithium battery, large amount of lithium slag (LS) discharged during lithium salts extraction process by using spodumene. High content of aluminosilicates and gypsum in LS make it an ideal alternative for mineral admixture and retarder in ordinary Portland cement. Based on above, a ternary compound cement by using clinker, LS and limestone (CC) was proposed in the study. Results showed that the LS could be substituted for calcined clay and gypsum simultaneously to prepare a ternary compound cement similar to limestone calcined clay cement. The prepared cement had longer setting time and better fluidity, and more than 120 % of 28 days compressive strength increasing rate compared to that of 3 days was also observed. The addition of CC could shorten the setting time and improve the workability of the ternary compound cement compared to that of cement with LS alone, due to the nucleation and filling effect of CC. Slow pozzolanic reaction of aluminosilicates in LS and the formation of monocarboaluminate (Mc) might contribute to the higher later mechanical performances of the ternary compound cements. In addition, synergistic hydration effect among clinker, LS and CC would hinder the transformation from AFt to AFm, increase the hydration products and refine the pore structures of the hydrated ternary compound cement system.