Strengthening of concrete beams in shear with mineral based composites : laboratory tests and theory

Today, there are many different repair and strengthening methods that might be used to upgrade a concrete structure. One such method involves CFRP (Carbon Fibre Reinforced Polymer) bonding. This method has proven to be usable for many different types of retrofitting applications. Even so, there are some disadvantages while using epoxy resins as a bonding agent, i.e. diffusion closeness, thermal compatibility, working environment and the minimum temperature of assemble. It is therefore of interest to replace the epoxy adhesive with a mineral based bonding agent, e.g. polymer modified mortars with similar properties as the base concrete that also is more working environmental friendly. A combination between the polymer modified mortar and fibre reinforced polymers (FRP) can be used for repair and strengthening of civil structures. This paper presents a pilot study of RC beams strengthened in shear with mineral based bonding agents and CFRP grids. The project is a collaboration project among Luleå University of Technology, Norut Teknologi AS and Denmark Technical University and is also a part of the European funded project "Sustainable Bridges". The results so far show that comparable strengthening results as for epoxy bonded systems can be achieved with MBC strengthening systems. The strengthening effect of the beams was 40 - 100 % compared to the unstrengthened reference beam. The theoretical model describes the load carrying capacity fairly well.Godkänd; 2006; 20070207 (ysko)