Improved Method And Mechanism Of Micro Fine Structure Of New-to-old Concrete Repaired Interface Layer

Based on the bond mechanism of new and old concrete repaired interface layer, an idea to significantly increase micro roughness of old concrete interface by using acid to wash it was proposed. The expectation was placed on to increase significantly contact area of old and new concrete, leading to a significantly enhancement of the bond strength. Through analysis and test muriatic acid was decided as washing liquor, rational acid concentration and washing time were also proposed. It was further proved that the modification cement mortar primer by introducing fly ash could significantly reduce the content of large crystal in new and old repaired interface layer. Two methods being used together could improve microstructure of new and old concrete repaired interface layer fully, leading to a significantly increase of bond strength. The bond improving mechanism was discussed, and a further research advice was put forward.