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Fiber Reinforced polymer for strengthening of reinforced concrete

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 Fiber-reinforced plastic (FRP) is a new technique to strengthen structures. Fiber-reinforced plastic has various types, such as a carbon-fiber-reinforced polymer (CFRP), glass fiber reinforced plastic (GFRP), and aramid fiber-reinforced polymer (AFRP).  The below table shows the mechanical properties of different fiber types. 

  

Table 1
we can notice that carbon fiber reinforced polymer possesses better properties compared to other types. For example, the tensile strength of CFRP extra-high strength can reach 6200 MPA compared to a maximum tensile strength of 4135 MPA of other fiber types.  

The FRP has various uses such as:
  • Improved seismic performance of masonry walls
  • Replacing missing steel reinforcement
  • Increasing the strength and ductility of columns
  • Increasing the loading capacity of structural elements
  • Correcting structural design and/or construction defects
  • Increasing resistance to seismic movement
  • Improving service life and durability
  • Structural upgrading to comply with current standards
The installation of FRP will pass through the following steps:
  • In the beginning, we need to remove the weak layer of concrete to ensure good bonding between the FRP sheets and concrete. The removal of the weak concrete layer can be done by sandblasting or by grinding. 
  • The next step is to clean the concrete surface. The cleaning can be done by pressurized air or vacuum. The purpose of this step is to remove the dust and any other debris. 
  • Primer can be applied to improve the bonding between the concrete surface and the adhesive. The primer can form a barrier that prevents the concrete moisture from reaching the adhesive. The used primer should be compatible with the adhesive to ensure good bonding. 
  • The FRP surface should be cleaned with a solvent such as acetone to ensure proper bonding with an adhesive. Sometimes the surface of FRP is protected with a special protection layer peel-ply. In this case, cleaning of the FRP is not required. The Peel-layer will be removed before the applying of adhesive.
  • Mixing of adhesive shall be according to manufacturing recommendation. The proportions of mixed ingredients shall be accurate and shall be respected to ensure proper adhesive bonding and performance. 
  • The next step is to apply the adhesive to FRP strips. The FRP shall completely cover the surface of FRP strips.
  • The next step is to place the FRP strips in their location. The fixing of FRP strips should be placed during the adhesive pot life to ensure good bonding between the concrete and FRP strips. A sufficient number of workers should place the FRP strip to avoid the formation of air pockets or adhesive contamination.  
  • The surface of FRP strips should be protected. The protection system should be compatible with FRP and concrete. 

Figure 1

Figure 2

Figure 3

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My name is Mohammad Hamdan, and I am a Civil/bridge Engineer with extensive professional background and experience in the field of construction. I have 10+ years of experience in the construction field. During my professional career, my emphasis has been placed on structural projects, mainly bridges, infrastructure and roads. Reading and practicing the design of structures is my passion.i was lucky to be a part of a big team that executed major highway interchanges. I believe in spreading the knowledge, thus, i compose these courses to share my experience and knowledge. My course focuses on the practical side of construction field. On other word, i am sharing some of what new engineers need to know about construction field. Beside working on construction field, i love writing some articles on my website ( curious civil engineer) Moreover, i wrote some engineering papers, you can check them  by searching my name on Google (Mohammad mamon Hamdan)