– To create openings in concrete walls is rather common today. In many cases the structures change their functions from apartments to offices, from offices to clinics, or one just wants to make from two small bedrooms a larger one. I have worked as consultant with such cases on several projects, says Gabriel Sas, Assistant Lecturer at Luleå University of Technology and manager of the project on behalf of Norut.
Traditionally, the area around an opening is reinforced with concrete or steel frame to regain the resistance of the concrete wall. In this project, we instead use fiber reinforced polymers (FRP), i.e. a stronger plastic material made out of carbon, similar to what is used in the aircraft industry. The technique is simple we attach the plastics to the surface of the concrete using a strong glue. The materials cost are slightly higher but if you look at the big picture (logistics required, volume of work, number of workers, etc.), the price is similar if not less.
Photo: Cosmin Popescu
– Together with Cosmin Popescu, the PhD candidate in charge of the project, we have tested this technique here at Complab. We designed several wall elements as in a typical concrete structure. We cut normal and double size door openings and we tested to see how much the walls can hold. Then we took identical walls we applied this new technique and test them again. The results are very promising. In some cases we managed to regain the entire capacity of a wall as for a wall without any door! I believe we can get even better results if we optimize the application pattern of the plastics. But this we would do in a continuation of the project, says Gabriel Sas.
The project is financed by Regionale Forskningsfond, Nord-Norge, NORUT, Skanska and SBUF. Without their financial support we wouldn’t have had obtained these results.