Fire Protection with Carbon Fiber Reinforcements
Concrete structures can present different pathologies for different reasons: project errors, execution failures, low quality of the materials, request of increase of loads in a reform or modification of a project, etc. Actions for repair and reinforce these structures are necessary.
An increasingly common solution for this type of problems is repairing through the application of composite strips, the most frequent of which is Carbon Fiber Reinforced Polymers (CFRPs) bonded by an Epoxy Resin. It is a method of easy application and very good results in the carrying capacity increase of the applied elements.
This system for repairing concrete elements has a main drawback, the fire behavior and the high temperatures of the binder resins. There are several types of resins to join the Carbon Fiber, such as phenols with a softening temperature of 200-300 ºC, but these have worse mechanical results than Epoxy resins, which have become for this reason the most used. The drawback of these Epoxy resins is that they lose the properties for which they have been designed at 81.4 ° C. At this temperature, both the mechanical properties and the ability of adhesion to the substrate are lost, resulting in detachments of the membrane.
Due to the increasing use of these types of solutions, from the R & D department of Mercor Tecresa, a Fire Protection system has been developed for these elements hurling a Carbon Fiber membrane of 50 mm at the Tecwool F mortar, achieving that during 120 minutes the CFRP does not reach the critical temperature of 81.4 ° C. The system is being tested under the current test standard UNE-EN 1363-1 Fire resistance tests. Part 1: General requirements.
This type of substrate usually presents adhesion problems because it lacks porosity or roughness. A simple method to achieve a correct bonding of the Tecwool F Mortarover the CFRP is to perform a fresh duster on the last layer of the membrane with silica sand thus achieving the desired roughness. It is also possible to subsequently paint the Tecwool F mortar with elastic acrylic coatings that form a barrier to the passage of water vapor. Before proceeding to paint it, always wait until the Tecwool F(28 days) mortar is baked.