Improvement in the Durability of Cracked Concrete Elements Injected With Synthetic Resin by Optimizing the Bond Behaviour

Cracked building elements are increasingly being repaired by the injection of reactive resins. The success of a repair not only depends on the choice of the right injection material but rather it is also influenced in a complex way by many practical construction conditions. This includes the non-positive injection of wet crack surfaces. At present very little information is available about the influence of processing and material-related parameters on the bond behaviour. The cause of premature bond failure must be sought in the microregions of the adhesive areas, wherefore the application of scanning electron microscopy is indispensable. The influence of different boundary conditions on the bond behaviour of the injected resin systems was investigated in several tests. In the first test unit with building elements, it could be shown that dry crack injection at a temperature generelly presents little difficulty. The investigation of 25 °C carbonated injected crack surfaces also presented positive results. However, the presence of water during the injection and the curing phase resulted in a reduction in the bond tensile strength. In cooperation with the chemical industry, the adhesive properties of some wet injected resins have been improved considerably.