• PO BOX 6446 North Ryde NSW 2113

    FCS Concrete Repairs Pty Ltd
    ABN 68 602 061 709

  • Call us 02 8203 4568

  • Email Address info@fcsconcreterepairs.com.au

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    Crack Injection Techniques are used for concrete crack repair and to stop active water leaks.

    It is important to repair cracks promptly because the ingress of water into the cracks will eventually cause the internal steel reinforcement to rust and expand during the oxidisation process. As the imbedded steel expands the surrounding concrete will be compromised and concrete spalling (concrete cancer) will occur.

    Hairline cracks or larger cracks will allow moisture into the concrete and enable this spalling to occur.

    Concrete crack injection is quick, effective and relatively inexpensive. By comparison, concrete spalling/cancer can be structurally damaging and very costly to repair. So it is essential to act quickly!

    Crack Injection is carried out by the following process and can be carried out with a minimum of disruption.


    The surface of the crack is sealed and allowed to cure to form a strong barrier which will prevent the injected material from escaping to the surface.

    Injection ports are also installed along the length of the cracking.

    After the sealant cures liquid epoxy or polyurethane resin is injected through each of the ports along the full length of the cracking.

    Examples of Material Used

    Prime Resins Prime Gel 2800 Strippable Surface Seal.

    Sikadur CF Normal Adhesive.

    Fosroc Nitofill LV.

    The cracks must be completely filled.

    Injection ports are removed.

    The entry of moisture has been prevented and the repair is complete!

    Generally low pressure injection is used however higher pressure injection is required for hairline cracks or where the crack is actively leaking.



    Epoxy has a bond strength much higher than concrete, welds the crack together and restores structural strength of the concrete.

    Epoxy is not appropriate for a wet area crack because moisture weakens its bond strength.

    Epoxy therefore eliminates movement (i.e. forms a rigid repair) and restores the structural integrity of the concrete structure. However where the concrete is subject to movement or has a continuing stress load the repair needs to be more flexible to prevent further cracking.

    Epoxy must be used however where the crack is structural.


    Polyurethane Foam is more flexible and can expand up to thirty times its initial volume to completely fill the voids within the concrete cracks.

    Polyurethane reacts with moisture in order to foam and expand so wet area cracks should be repaired with this material.

    The flexibility of the Polyurethane allows the repair to move with the expansion and contraction of the structure.

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