Influence of silane coupling agent on quality of interfacial transition zone between concrete substrate and repair materials

Silane coupling agent (SCA) was introduced as a modifying material to significantly improve the bond quality of the repaired interfacial transition zone. SCA aqueous solutions with various concentrations were used to coat the surfaces of a granite and of old concrete substrates before applying the repair materials. Both pull-off bond strength test and microstructure observation of the different repair interfacial layers were performed. The test results show that coating a concrete substrate with a SCA aqueous solution with an appropriate concentration can noticeably modify the microstructure of the interfacial transition zone, and therefore, significantly increase the bond strength.