Effects of lithium carbonate and polycarboxylate water reducer on the properties of high-belite sulfoaluminate cement paste

High-belite sulfoaluminate (HBCSA) cement has gained global attention for its low firing temperature and thus reduced carbon dioxide emissions, showing potential as a sulfoaluminate cement substitute. In this work, polycarboxylate water reducer (PCE) and lithium carbonate (LC) were used in an attempt to address the fast setting/hardening and unstable strength development of HBCSA cement paste. Using various dosages of LC and PCE, tests for fluidity, setting time, mechanical properties, hydration heat, adsorption and chemically bound water were conducted, along with X-ray diffraction and scanning electron microscopy. Compared with the addition of LC alone, PCE–LC compounding significantly enhanced the adsorption of PCE on the HBCSA surface, improving fluidity and prolonging the setting time. It also reduced early hydration rate but increased cumulative heat release. Microscopically, 28-day hydrated samples with 0.2% LC and 0.8% PCE exhibited shortened, diverse short-columnar ettringite with higher density, boosting the 28-day compressive strength to 82.4 MPa.