CFRP plate bonding is a technique where flat strips of carbon fiber composite – also called laminates or carbon fiber plates – are epoxy-bonded to structural members to carry tensile forces. This method is widely used for flexural strengthening of concrete beams and slabs (by bonding plates on the soffit or bottom) and for reducing deflection or crack widths. It can also be applied for axial reinforcement on walls or for strengthening concrete columns (by bonding vertical strips). Key points about CFRP plate systems:

• High Stiffness and Strength: Carbon fiber strips have a high elastic modulus (often ≥ 165 GPa, comparable to steel) and very high tensile strength (often over 2,000 MPa). When bonded to concrete, they can take a significant portion of tensile stress, thereby increasing the member’s load capacity and stiffness. For example, ZRETE’s carbon fiber strips are made with premium 12K fiber and epoxy, achieving tensile strengths over 2.4 GPa (Grade I high-strength) and elongation >1.6%, surpassing national standards for CFRP laminates.

• Externally Bonded or Near-Surface Mounted: CFRP plates can be glued to the surface (external bonding) or placed in slits cut into the concrete cover (NSM technique) and then grouted with epoxy. NSM provides better protection and aesthetics (the strip is embedded and not exposed) and can improve bond performance in some cases.

• No Welding or Heavy Lifting: Unlike steel plates which might require bolting or welding and are heavy to handle, CFRP strips are lightweight and simply bonded with adhesives. This makes installation faster and often does not require extensive scaffolding or large crews.

• Use in Combination with Fabrics: CFRP plates primarily address flexural needs; they are often complemented by FRP fabrics or wraps for shear or confinement if needed. This holistic approach ensures bending, shear, and torsion capacities are all enhanced as requiredsika.com.

ZRETE provides high-thixotropy epoxy adhesives specifically for plate bonding, such as JGN807 High Thixotropy CFRP Strip Adhesive. This adhesive has a paste-like consistency (non-sag) which is crucial for bonding plates overhead on beams without drips, and it cures to form a durable bond between the CFRP strip and concrete. The thixotropic nature also allows filling small gaps or irregularities, ensuring full contact. Using the correct adhesive is essential for force transfer from the concrete to the plate.

Products (CFRP Plate Systems):

• ZRETE Carbon Fiber Strips – Pultruded CFRP laminates for external bonding on concrete; available in various sizes to increase flexural capacity of beams, slabs, and walls.

• JGN807 High Thixotropy CFRP Strip Adhesive – Specialized two-component epoxy for bonding CFRP plates to concrete (including overhead applications) with excellent thixotropy and bond strength.