Infrared–Resin Crack Measurement and Preventive Work Technology for Maintenance

Abstract

The use of thermography as a nondestructive evaluation technique is increasingly popular for maintaining concrete structures. Most inspections merely evaluate the locations and shapes of defects on surfaces. To address this shortcoming, it proposes an inspection method and preventive work using a coating-type resin sensor combined with an infrared camera. No method has been developed to assess the depth of defects. In this approach, infrared-reactive resin is applied. Thermographic images of the target area are captured sequentially. Temperature curves obtained at each pixel during the cooling process are analyzed using Fourier transform to differentiate defect states in various parts of the temperature distribution. The temperature change is found to be correlated with the defect size. Approximately 5% aluminum powder is mixed into the applied gel resin. Because of its specific gravity, it tends to concentrate in areas damaged by compression failure or to float. This report discusses technologies related to identification of defects and measuring their size in infrared-reactive resin, with examination of the effectiveness of measures to prevent scattering and collapse of defects caused by structural degradation. A concentric loading test on reinforced concrete columns confined by gel resin ties is described herein. Test variables include concrete compressive strength of 232–244 N/mm<sup>2</sup>, both below and above the equipment hole that caused the defect, and to measure the relation, a comparison with test specimens that are free of defects.