Strengthening Using Carbon Laminates

Fibre Wrapping

Pre-Cured Carbon Fibre composites in the form of laminates, more popularly known as CFK laminates, is a new material used for external strengthening and retrofitting of RCC members.

As laminates have a very high tensile strength to weight ratio, around 8-9 times of steel, which makes it a very suitable material for providing extra strength and hence increasing the load bearing capacity of members.

The most common form is Non Pre-Stressed laminates mounted on the surface of concrete. It increases the shear resistance and flexural strength. This near surface mounted technique is based on fixing, by epoxy adhesive, CFK laminates into pre-cut slits opened in the concrete cover of the lateral surface of beams and slabs. When more load is applied on the member slab or beam the laminates become active and share the load on themselves. Hence increasing the load which the member can take.

At the ends of laminate anchor plates, called non Pre-Stressing Plates, are fixed with help of adhesive so that the laminates does not peel off the concrete surface in future.


Cube Testing is done extensively over cylindrical and rectangular cubes with Fibre wrapped system and they show improved enhancement in their flextural and compressive strengths.

  • Tensile testing of the laminates according to ASTM standards for their load bearing capacity.
  • Pull-Off test for the bonding strength of adhesive and its efficacy to transfer the loads.