4. Conclusions
Based on the experimental results, the following conclusions can be drawn:
(1) Ester can make the end time of cement hydration induction longer and delay the occurrence of the second exothermic peak, indicating that it has a delayed effect on the hydration reaction rate of cement at early stage (hydration induction period and acceleration period).
(2) TG, TB, DMO, and EAC increased the second exothermic peak and hydration degree of cement and promoted the formation of hydration products and the optimization of the pore structure. Macroscopic performance is that mechanical properties of cement at 3 d and 28 d improved significantly. TMP has a retarding effect on cement and reduces the second exothermic peak of cement and inhibits the formation of early hydration products, which reduces the strength of cement at 3 d, but it improves the strength of cement at 28 d.
(3) 0e effect of five kinds esters on the hydration and hardening of cement was basically followed by TG> TB> DMO> EAC> TMP. In terms of the molecular structure, for organic compounds containing only ester groups, the higher the number of ester groups, the greater the effect on the hydration of cement. 0e introduction of other functional groups (such as phosphate or borate) will influence the effect of the esters.
