Experimental and numerical investigation on the thermal performance of recycled aggregate concrete

As a green building material, recycled aggregate concrete (RAC) can reduce construction solid waste and carbon emissions. In this paper, a combination of macroscale physical experiments of thermal performance and mesoscale numerical simulations of heat transfer were used to investigate the thermal conductivity (TC) of RAC. Firstly, the TC of RAC was measured using the steady-state method. Secondly, the mesoscale numerical analysis method of steady-state heat transfer of RAC was established by self-programming. Finally, by comparing with experimental results, the validity of the mesoscale numerical analysis method in this paper is verified. The results indicates that the TC of RAC is positively correlated with the recycled coarse aggregate dosage and the TC of each component, while it is negatively correlated with the water-binder ratio, the recycled fine aggregate replacement ratio, the old mortar adhesion ratio, the interface transition zone thickness, and the porosity. The six-phase mesoscale model of random convex polygonal aggregate for RAC constructed in this paper can effectively predict the TC of RAC, which provides a new idea for analyzing the TC of RAC.