Resin Injection of Cracks with Changing Width

Cracks in concrete usually have to be closed either to make the structure water tight again or to protect the reinforcement against corrosion. As many cracks are not stable in their width, a repair is only successful, when the injected material can change its volume according to the volume-change of the crack. The volume of gases can be changed to a great amount by applying small external forces. To achieve volume compressibility of.an injecting resin combined with watertightness, plastic micro-balloons or micro-spheres (average diameter 0,04 mm) are inserted into the resin. Using a rubberlike epoxy resin, volume deformations of more than 50% are possible. If the epoxy resin is stiff (modulus of elasticity about 2000 N/mm2) forces can be transmitted still allowing a volume change of 10 to 20%. The applied deformations are fully reversible.