Calculation Method of Effective Thermal Conductivity of Steel Fiber Reinforced Concrete after High Temperature

Abstract

Abstract: The thermal conductivity of steel fiber reinforced concrete (SFRC) is a primary property for structure fire resistance performance analysis. It is of great significance to estimate the thermal conductivity at/after high temperature quickly and accurately. For this demand, a multi-scale method for thermal conductivity of SFRC was proposed, featuring with the thermal cracking behavior at high temperature, namely the interfacial thermal resistance (ITR), rather than the temperature-dependent decreasing law of components thermal conductivity. Afterward, the experiments on the thermal conductivity and porosity of mortar, high strength concrete, and SFRC with 1% and 2% (volume fraction) fiber heated up to various temperatures (20 ℃, 60 ℃, 150 ℃, 300 ℃, 450 ℃, 600 ℃) were performed to validate the proposed model. The results show that the numerical predictions satisfy the experimental data very well when the ITR coefficient is assumed to linearly increases with heating temperatures.When the temperature reaches 600 ℃, the decreases of thermal conductivity of mortar, high strength concrete and SFRC with fiber (volume fraction 1% to 2%) caused by ITR effect are about 50%, 36%, 7% and 12%, respectively. When the ITR coefficient of high strength concrete is 0.4 and the ITR coefficient of SFRC is 1.0, the addition of particles with good thermal conductivity has no help to increase the effective thermal conductivity of composite materials.

Key words: steel fiber reinforced concrete, high temperature, effective thermal conductivity, thermal crack, interfacial thermal resistance

CLC Number:

TU528.58

ZHU De, HAN Yang, DUAN Junfeng, SHEN Lei, YAO Xiupeng, CAO Maosen. Calculation Method of Effective Thermal Conductivity of Steel Fiber Reinforced Concrete after High Temperature[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(5): 1510-1519.

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