Influence of silica fume and metakaolin with two different types of interfacial adhesives on the bond strength of repaired concrete

• The factors affecting the bond strength are assessed.
• Three different types of pozzolans are applied through the study.
• Two sorts of adhesives are evaluated as coating between substrate and overlay.
• Chemical components of pozzolan should be taken into account in addition to the coating type.
• Using polymer-based adhesive adjacent to the water is not suitable.

In this article, the factors affecting the bond strength are studied through slant shear tests made on 168 samples in two phases. Effects of silica fume (SF) and two types of metakaolin (MA, MB) replacement with a portion of cement in concrete repair are studied as the first phase. The second phase consists of plain cement slurry (PCS) and bonding slurry (BS) as the interfacial adhesives. Only metakaolin type B could improve the bond strength, and best results were obtained in PCS applied specimens. Applying BS in concrete repairs exposed to the water was not suitable to be used as an interfacial adhesive. In applying pozzolan the sort of interfacial adhesive in addition to the chemical components of the pozzolan must be considered.