Abstract
Thermal conductivity plays a significant role in controlling thermal cracking of cement-based materials. In this study, the thermal conductivity of cement paste at an early age was measured by the hot plate method. The test results showed that the thermal conductivity of cement paste decreased with the increase of water/cement ratio and curing age. Meanwhile, a multiphase model for the thermal conductivity of cement paste was proposed and used to study the influence of saturation and curing temperature on the thermal conductivity of cement paste. To determine the parameters involved in this model, the thermal conductivity of each phase in cement paste was calculated by the molecular dynamic simulation method, and the hydration of cement was simulated by the Virtual Cement and Concrete Testing Laboratory. The inversion results showed that the relative error between experimental and simulation results lay between 1.1% and 6.5%. The thermal conductivity of paste in the saturated condition was 14.9–32.3% higher than that in the dry state. With the curing temperature increasing from 10 °C to 60 °C, the thermal conductivity of cement paste decreased by 3.9–4.9% depending on the water/cement ratio.
Highlights
The results showed that this model could be used to predict the thermal conductivity of cement paste at an early age
In view of the above, this paper studied the thermal conductivity of cement pastes with different water/cement ratios (0.34, 0.41 and 0.49) and curing ages
Ulm and Pellenq [23] have predicted the thermal conductivity of C3 S, C2 S, calcium silicate hydrate (CSH) and calcium hydroxide (CH) by molecular dynamic (MD) simulation and demonstrated that thermal conductivities of C3 S, C2 S, CSH and CH were 3.35, 3.45, 0.98 and 1.32 W/(m K), respectively
Summary
The results showed that this model could be used to predict the thermal conductivity of cement paste at an early age. Based on the test results, a regression model for the thermal conductivity of cement paste was established. The research on the prediction model which can link constituent phase properties to the overall thermal conductivity of cement paste is still very minimal. The hydration process of cement was simulated by the Virtual Cement and Concrete Testing Laboratory (VCCTL) Based on those two studies, a multiphase model, which can link constituent phase conductivity to the overall thermal conductivity of cement paste, was proposed. The influence of saturation and curing temperature on the thermal conductivity of cement paste was studied with the proposed model
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