Study on the influence of temperature rise inhibitor on the early-age temperature field of moderate heat Portland cement (MHC) concrete

The employment of moderate heat Portland cement (MHC) and temperature rise inhibitor (TRI) are two important methods to reduce the early temperature rise of mass concrete in engineering. This study evaluated the impact of TRI on the temperature control effect and temperature field of MHC concrete at early-age. The thermal parameters of cement mortar, the adiabatic temperature rise and the hydration product of MHC concrete with varying TRI contents (0 %, 0.4 %, 0.8 %, 1.2 %) were tested. Results showed that both thermal conductivity and specific heat capacity of cement mortar inversely correlate with age, with higher TRI content enhancing specific heat capacity and reducing thermal conductivity; TRI can effectively reduce the adiabatic temperature rise of MHC concrete within 7 days, most significant at 24 h. Using the Krstulovic-Dabic model to analyze MHC's hydration process, and the results showed that the addition of TRI reduces the reaction rate in three stages (Crystallization Nucleation and Crystal Growth (NG), Phase Boundary Reaction (I) and Diffusion Reaction (D)), hinders the nucleation process, and shortens I stage. The microscopic temperature field simulation showed that TRI can reduce the early temperature gradient of MHC concrete under different aggregate characteristics, and its temperature control effect is more significant in MHC concrete with lower coarse aggregate content and smaller aggregate particle size. In addition, this paper analyzed the uniformity of temperature field in MHC concrete with TRI under different aggregate characteristics, and found that the early-age temperature field of MHC concrete has a smaller variance after adding TRI, indicating it becomes more uniform.