Investigations on durability behaviour of concrete repair systems exposed to outdoor weathering

摘要

Till the eighties of the last century no technical standards existed for concrete repair products. During this period of increasing damages in concrete structures a large number of quite different repair materials and systems were developed, which should be able to improve the durability of concrete structures furtheron. However, a lot of these materials could not ensure a sufficient durability by themselves. In this phase numerous large-scale specimens were produced and applied with quite different concrete repair systems based on e.g. polymer modified cement concretes (PCC's), epoxy concretes (EC's), cement concretes (CC's) as well as sprayed concretes. Investigations on some of these specimens were already carried out 1, 4.5 and 7 years after preparation. Most of the specimens, however, were stored in outdoor exposure conditions for more than 20 years now. In current investigations the main relevant properties of repair systems are tested on these twenty years old specimens. In most cases the bond strength of the repair system is quite above the common limit value of 1.5 N/mm~2. For some specimens visible cracks in the coating did not result in a corrosion of the protected rebars, although the concrete cover was only 3 to 5 mm.