Identification of reinforcement and voids in concrete structures using ground penetrating radar

Abstract

For the construction of infrastructures, reinforced and pre-stressed concrete are widely used. The concrete is mixed at site or obtained from a ready mixed plant. Most of the time, the quality of the concrete mix is guaranteed but due to the congestion of reinforcement and the quality control exercised during placing and vibrating, honeycombs and voids are likely to present in the hardened concrete. The presence of voids leads to the early deterioration of concrete and corrosion also sets in. The corrosion of reinforcement cause damage to the cover concrete and also section loss in the area of steel. In the case of pre-stressed concrete members, the corrosion leads to a catastrophic failure without any warning. Hence, it becomes necessary to evaluate the condition of concrete using NDT and PDT methods. The UPV method which is adopted till now gives the relative quality of concrete. The Ground Penetrating Radar (GPR) which is an advanced NDT method can be used to locate the voids and also to identify the presence of reinforcement. The advantage in GPR is that, it is a line measurement and the details in the cross section can be evaluated in a single run. This paper highlights the efficiency of the radar method in identifying the voids and the reinforcements.