Effect of base surface roughness, cutting depth and coating thickness on adhesion of inorganic repair materials for repairing concrete channels in the pre-survey and monitoring survey

Many open concrete channels in Japan have exceeded their standard service life and have decreased function due to deterioration. To maintain efficient drainage and transport and distribution of water to fields, it is necessary to extend the service life by repairing the channels. Inorganic repair material has been used for repairing concrete and has a number of performance requirements. For example, adhesion is an important performance requirement to ensure that repair material does not detach from the open concrete channel. It is evaluated by an adhesion strength test, which is performed in the pre-survey and the monitoring survey and has three main test standards. Because the test standards are intended to be performed in a laboratory, the monitoring survey can refer only to the test standards, and there is no standard for the monitoring survey. Furthermore, unlike the base surface in the test standards, the open channel surface is uneven before repair. Therefore, the pre-survey is not sufficient to evaluate the adhesion because it does not consider the construction environment. In this study, we proposed test methods for the monitoring survey and identified considerations for the pre-survey of base surface roughness, coating thickness, and cutting depth. Adhesion strength decreased as the cutting depth increased or the base surface roughness increased. Therefore, the base surface roughness should be measured in the pre-survey, and the monitoring survey should be conducted at points where the base surface roughness is the same. In addition, the cutting depth should be consistent in the monitoring survey.