Nano particle modified bonding agent for concrete repair

The adhesive force at new-old concrete interface of the repairing concrete structure is usually very weak, a new type of nano particle modified new-old concrete interface agent was prepared in this paper to enhance the interfacial bond of the new-old concrete basing on the huge surface area and high activity of nano particles. The results indicate that the splitting strengths on the top surface or fracture surfaces treating with the nano particle modified new-old concrete interface agent between the new and old concretes are much higher than those treating with ordinary fly ash interface agent. The modification effect of nano particle on the bond of fracture surface is much more remarkable than that of top surface. The surface agent paste is more effective to repair the top surface while the surface agent mortar is more suitable to repair the fracture surface. The hydration product portlandite is depleted by nano particle so the directional crystallization of the portlandite is baffled, the nano particle can form some chemical bonds at the interfacial zone so the adhesive force is enhanced, the new-old concrete become an integral bulk with the treatment of nano particle modified interface bonding agent. Copyright ASCE 2007.