Synergistic Effect of C-S-H–PCE and Al2(SO4)3 on the Hydration Properties of Lithium Slag–Cement Composite Binder

Abstract

To enhance the early strength development of lithium slag composite binder, synergistic action of calcium silicate hydrates (C─ S─ Hs)–polycarboxylate (PCE) and Al2(SO4)3 on the hydration properties of lithium slag–cement binder was studied. Results showed that C─ S─ H─ PCE and Al2(SO4)3 synergistically facilitated the solidification and hardening of composite binder. The combination of 2% C─ S─ H─ PCE and 6% Al2(SO4)3 enhanced the compressive strength of the composite cement mortar at 1 day, 3 days, and 28 days by 37.6%, 33.1%, and 9.9%, respectively. By providing nucleation sites, C─ S─ H─ PCE facilitated the early hydration of silicates and the pozzolanic reaction of lithium slag, leading to shortened induction period, advanced heat release peak, increased total hydration heat release, and increased production of portlandite (CH) crystals. Aluminum sulfate facilitated dissolution of lithium slag (LS) and expedited the production of ettringite (AFt). The synergistic adoption of C─ S─ H─ PCE and Al2(SO4)3 facilitated the hydration of both clinker and LS, and the hydration products were more abundant, contributing to a more compact matrix.