RELATED MATERIALS:
- MEGAWRAP-200 carbon fibre fabric for structural reinforcement
- EPOMAX-LD two-component epoxy impregnation adhesive for composite fabrics
- EPOMAX-EK two-component epoxy putty
- MEGACRET-40 strong repair mortar, fibre-reinforced
I. NATURE OF THE PROBLEM – REQUIREMENTS:
The need to increase the shear strength of a concrete beam arises in cases such as increased design loads or change of use, adaptation of existing structures to updated regulations, ageing of building materials, corrosion of the reinforcement and construction defects, or repair of reinforced-concrete members after earthquakes. The strengthening system must improve the beam’s shear capacity, prevent brittle shear failure and enhance its ductility under cyclic loading.
II. SOLUTION:
Shear strengthening is achieved by bonding carbon fibre jackets or strips (MEGAWRAP-200) around the beam in the transverse direction using EPOMAX-LD epoxy resin. Continuous or U-shaped jackets, closed jackets or jackets with an open top can be used depending on access. MEGAWRAP-200 jackets provide increased shear strength, drastically reduce the risk of brittle failure, improve behaviour under cyclic loads by enhancing ductility and are resistant to corrosion and ageing. Compared to steel or concrete jackets they add very little weight or thickness and are easy to install.
III. APPLICATION:
- Substrate preparation: Remove loose concrete, plaster, paint, grease or oils. Thoroughly clean the surface and roughen it with a wire brush. Repair cracks with resin injections. Level surface irregularities using MEGACRET-40 mortar or EPOMAX-EK epoxy putty so that the surface is as even as possible.
- Priming and fabric application: Coat the prepared surface with EPOMAX-LD resin. Cut MEGAWRAP-200 fabric into strips of the required width and length. Lay the fabric onto the wet resin and press it firmly with a hard roller to achieve full contact, good impregnation and removal of air bubbles. If some dry areas remain, brush more resin over them. For multiple layers, apply additional fabric before the previous layer has fully cured or re-sand if it has cured. Impregnate the final layer with EPOMAX-LD and sprinkle quartz sand onto the fresh resin to provide a mechanical key for subsequent coating if required.
IV. REMARKS:
- Excellent surface preparation and proper anchorage at the edges of the jacket are essential for effective shear strengthening. Pull-off tests may be performed to verify substrate strength.
- During cutting and installation of the fabric care should be taken to avoid folding or creasing; the surface must be clean before placing the fabric.
- The open working time of epoxy resins decreases as temperature rises; prepare small batches and apply promptly. Do not apply if the substrate temperature is below +5 °C.
- Protect the fabric and resin from high temperatures and direct sunlight before and after application. Wear protective gloves and goggles and follow the safety instructions.
- MEGAWRAP-200 carbon fibre fabric for structural reinforcement
- EPOMAX-LD two-component epoxy impregnation adhesive for composite fabrics
- EPOMAX-EK two-component epoxy putty
- MEGACRET-40 strong repair mortar, fibre-reinforced
I. NATURE OF THE PROBLEM – REQUIREMENTS:
The need to increase the shear strength of a concrete beam arises in cases such as increased design loads or change of use, adaptation of existing structures to updated regulations, ageing of building materials, corrosion of the reinforcement and construction defects, or repair of reinforced-concrete members after earthquakes. The strengthening system must improve the beam’s shear capacity, prevent brittle shear failure and enhance its ductility under cyclic loading.
II. SOLUTION:
Shear strengthening is achieved by bonding carbon fibre jackets or strips (MEGAWRAP-200) around the beam in the transverse direction using EPOMAX-LD epoxy resin. Continuous or U-shaped jackets, closed jackets or jackets with an open top can be used depending on access. MEGAWRAP-200 jackets provide increased shear strength, drastically reduce the risk of brittle failure, improve behaviour under cyclic loads by enhancing ductility and are resistant to corrosion and ageing. Compared to steel or concrete jackets they add very little weight or thickness and are easy to install.
III. APPLICATION:
- Substrate preparation: Remove loose concrete, plaster, paint, grease or oils. Thoroughly clean the surface and roughen it with a wire brush. Repair cracks with resin injections. Level surface irregularities using MEGACRET-40 mortar or EPOMAX-EK epoxy putty so that the surface is as even as possible.
- Priming and fabric application: Coat the prepared surface with EPOMAX-LD resin. Cut MEGAWRAP-200 fabric into strips of the required width and length. Lay the fabric onto the wet resin and press it firmly with a hard roller to achieve full contact, good impregnation and removal of air bubbles. If some dry areas remain, brush more resin over them. For multiple layers, apply additional fabric before the previous layer has fully cured or re-sand if it has cured. Impregnate the final layer with EPOMAX-LD and sprinkle quartz sand onto the fresh resin to provide a mechanical key for subsequent coating if required.
IV. REMARKS:
- Excellent surface preparation and proper anchorage at the edges of the jacket are essential for effective shear strengthening. Pull-off tests may be performed to verify substrate strength.
- During cutting and installation of the fabric care should be taken to avoid folding or creasing; the surface must be clean before placing the fabric.
- The open working time of epoxy resins decreases as temperature rises; prepare small batches and apply promptly. Do not apply if the substrate temperature is below +5 °C.
- Protect the fabric and resin from high temperatures and direct sunlight before and after application. Wear protective gloves and goggles and follow the safety instructions.
