Thermal conductivity of coarse aggregate, cement mortar as well as concrete were measured by means of
a guarded hot plate apparatus and/or a transient plane source. Influences of sand ratio, type and volume
fraction of aggregate, water–cement ratio, saturation degree and load level on thermal conductivity of
concrete were investigated. By using the theoretical model for thermal conductivity of composite materials,
interfacial thermal resistance between cement mortar and coarse aggregate were studied further.
The results show that thermal conductivity of concrete increases with the increasing saturation degree,
volume fraction and thermal conductivity of aggregate, but decreases with the increasing water–cement
ratio and load level. And interfacial thermal resistance coefficient decreases with the increasing saturation
degree; therefore, interfacial thermal resistance must be considered when calculating thermal conductivity
of concrete. Finally, mesoscale models were established for thermal conductivity of undamaged
concrete in dry and unsaturated states based on the Maxwell’s model. In addition, a mesoscale model was
proposed for thermal conductivity of damaged concrete; this model is based on the assumption that
damaged concrete was isotropic and damaged phase was served as an insulator. Mesoscale models can
be used to predict the effective thermal conductivity of concrete under different states and the predicted
values were all in acceptable agreement with the experimental values.