Synthesis Of Hydrated Calcium Silicate And Its Effect On The Properties Of Cement-based Mortar

The synthesis of hydrated calcium silicate is considered as a new kind of cement based material additive,but its properties are closely related to the synthesis process.On the basis of previous researches,the effects of calcium-silicon ratio,reaction temperature,reaction time and water-solid ratio on the microstructure,composition and morphology of hydrated calcium silicate were discussed,and the effect of hydrated calcium silicate on the early mechanical properties of mortar under different reaction conditions was studied,and the synthesis process of calcium silicate was optimized,then the influence of cement and cement-based mortar on its properties is studied,the related research conclusions are as follows:With the increase of calcium-silicon ratio?0.8?1.2?1.5?,the d-spacing of hydrated calcium silicate decreased gradually,the characteristic peaks of Q² and Q¹moved to the lower wave number and the Q²/Q¹ ratio reduced,indicating a decrease in the polymerization degree of hydrated calcium silicate,and the micro-morphology of hydrated calcium silicate changed from layer to irregular aggregates and became denser.With the increase of reaction temperature?20??60??80??100??,the d-spacing of hydrated calcium silicate decreased gradually,the characteristic peaks of Q² and Q¹ moved to the higher wave number and the Q²/Q¹ ratio increased,indicating its polymerization degree increased,and the micro-morphology of hydrated calcium silicate changed from irregular aggregates to layer.With the reaction time?3d?5d?7d?prolonged,the d-spacing of hydrated calcium silicate decreased gradually,the Q² and Q¹ characteristic peaks move to the the higher wave number and the Q²/Q¹ ratio increased,which indicated that the polymerization degree of the hydrated calcium silicate increased.With the increase of the water-solid ratio?10?15?20?30?40?,the d-spacing of hydrated calcium silicate increased gradually,and and the micro-morphology of hydrated calcium silicate changed from irregular aggregates to layer.Hydrated calcium silicate could improve the early strength of mortar and the late strength did not degenerated,at the same time,it was helpful to improve the frost resistance and impermeability of mortar;Na₂SO₄ also improved the early strength of mortar,but caused the late strength shrinkage and reduced the frost resistance and impermeability of mortar.The two additives promoted the early hydration of cement,advanced the heat release peak of the cement,shortened the cement setting time as well.