System for Control of Concrete Continuity of Steel Reinforced Concrete Structures Based on Thermal Imaging Method

Abstract

There is a problem of concrete continuity control after concreting in the increasingly popular steel-reinforced concrete structures where the outer steel shell is a fixed formwork and there is no visual inspection of the hardened concrete surface – these are mainly tubular concrete structures and steel-reinforced concrete structures with external plate reinforcement. The aim of the work is to develop a new system for concrete continuity control of reinforced concrete structures based on the thermal imaging method, which will make it possible to detect significant defects in the form of voids and unconcreted areas, which can be critical after concreting, in structures with a closed concrete surface for inspection without opening the metal shell. The proposed inspection system is based on thermal imaging of the surface metal immediately after concreting while the concrete is curing. This is possible because there is a large heat release during the curing and strength gain of the concrete. In areas within the structure where there is a defect – a void, unconcreted area, debris, etc., i.e. where there is no solid contact between the concrete and the external steel plate, the heat transfer will be less efficient and this can be detected with the thermal imager, if necessary, with forced heat removal. It is possible to obtain similar results when performing the reverse task of heating the structure from the outside. The experimental results obtained, together with the laws of thermal engineering describing the transfer of heat between different materials, allow us to state that the proposed method will work successfully. At present, there are no other non-destructive techniques for detecting and searching for internal defects in steel and reinforced concrete structures, which allow to determine the exact location and parameters of the defect. The proposed new technique has been tested on several small samples, but it can already be said that after full-scale studies, it will be suitable for structures of different types and configurations, taking into account the thickness of the metal, the volume of the structure, etc.