A novel heterogeneous model of concrete for numerical modelling of ground penetrating radar

•Realistic GPR modelling of concrete was considered.•A novel numerical heterogeneous model of concrete was developed.•The algorithm of determining substitute values of material constants was presented.•Our approach was evaluated on a concrete laboratory specimen and concrete bridge. The ground penetrating radar (GPR) method has increasingly been applied in the non-destructive testing of reinforced concrete structures. The most common approach to the modelling of radar waves is to consider concrete as a homogeneous material. This paper proposes a novel, heterogeneous, numerical model of concrete for exhaustive interpretation of GPR data. An algorithm for determining the substitute values of the material constants of concrete is developed, based on the modified complex refractive index method. Experimental surveys and numerical simulations are conducted on a concrete laboratory sample with a controlled degree of saturation, and on a real concrete slab with two different degrees of saturation. The results indicate that the proposed model is fully capable of realistic finite-difference time-domain modelling of concrete for ground penetrating radar diagnostics of civil engineering structures with changing water content.