Research on influencing factors and time-varying model of thermal conductivity of concrete at early age

The thermal conductivity of concrete was investigated under the unsaturated condition during early curing. Based on the improved steady-state method, the thermal conductivity of unsaturated concrete at different ages under curing at the constant temperature of 20 ℃, 5 ℃, and −5 ℃ was tested. The influences of the water-binder ratio, initial air content, fly ash content, curing age, and curing temperature on the thermal conductivity of concrete were analyzed. The water-binder ratio, initial air content, fly ash content, curing age, and curing temperature are inversely proportional to the thermal conductivity of early age concrete. Through the analysis of the correlation between these factors and the thermal conductivity, the correlation between various factors and the thermal conductivity of concrete from large to small is as follows: curing temperature, initial air content, curing age, water-binder ratio, fly ash content. A multiple regression prediction time-varying model with acceptable accuracy is proposed to ensure the accuracy of the effective thermal conductivity prediction.