Abstract
The weak interfacial transition zone between new and old concrete is always paid much attention and controls many properties of repaired concrete, The present work reports a study on the influence of the silica fume on the adhesion of reactive powder concrete (RPC), as a concrete restoration material, with the ordinary concrete (OC) substrate. The results showed that, the silica fume presence in the interfacial transition zone significantly enhances the adhesion strength between RPC and OC substrate. Furthermore, the silica fume particles consume calcium hydroxide, which is in attendance in the interfacial transition zone, and make the zone more dense, uniform and tough.