Effects of lithium carbonate and nano-calcium carbonate on the hydration and properties of calcium sulfoaluminate cementitious grout

The urgent repair needed for growing projects has significantly increased the demand for rapid repair materials. Lithium carbonate (LC) plays an important role as a set accelerator in improving the performance of rapid repair cementitious materials. This study explores the effects of compounding LC and nano-calcium carbonate (NC) on the hydration and properties of calcium sulfoaluminate (CSA) cementitious grout, including setting time, compressive strength, electrical resistivity, heat of hydration, autogenous shrinkage, drying shrinkage, electrical conductivity, pH of the pore solution and hydration products of the grout. The heat of hydration tests reveal that the incorporation of LC and NC significantly increased the heat of hydration of the CSA cementitious grout in the first 17 h, but decreased the cumulative heat of hydration in the later ages. Excessively fast early-age hydration reaction leads to the transformation of ettringite and retards the later-age hydration process. In addition to significantly shortening setting time and increasing early-age strength, the incorporation of LC and NC into CSA cementitious grout also promotes the growth of ettringite and reduces autogenous shrinkage and drying shrinkage of the grout.