Mesoscopic numerical simulation of effective thermal conductivity of tensile cracked concrete

• Tensile cracking behavior of concrete seriously influences thermal conductivity.
• Develop a method to calculate the conductivity of tensile cracked concrete.
• Present the relation between thermal conductivity and tension strain of concrete.
• Discover the mechanism behind the drop of tensile cracked concrete conductivity.
• Commend a theoretical model to estimate the tensile cracked concrete conductivity.

The pronounced decrease of effective thermal conductivity (ETC) due to cracking behavior of concrete will change the temperature profile in concrete structures, indirectly inducing the redistribution of thermal stresses. To evaluate this phenomenon, this paper presents a mesoscopic numerical method that is capable of quantitatively evaluating the effect of cracking behavior on concrete ETC. With this method, the development of ETC during uniaxial tension test of concrete is investigated and main conclusions are drawn as follows: (a) the ETC decreases greatly when micro-cracks initiate, and then becomes anisotropic when micro-cracks further propagate; (b) the cracked concrete ETC and its decrease rate nonlinearly increase with aggregate volume fraction (AVF); (c) the drop of ETC in specimens made by circle aggregates is greater than that in specimens made by arbitrary polygon aggregates, and their difference becomes more pronounced with the increase of AVF; (d) these numerical results can be utilized to determine uncertain parameters when estimating cracked concrete ETC using a recommended semi-theoretical model.