Abstract: A method for the grouting of an unbonded post-tensioned cable in a concrete structure which cable is enclosed in a cable sheath is disclosed. The method includes the steps of pumping a curable hydrophobic grouting material, for example a polyurethane resin into the cable sheath to fill a selected length of the cable sheath with the grouting material and continuing the injection until the selected length of the sheath is filled with the grouting material and the material expelled from the sheath no longer includes any admixed water. Infiltrated water in the cable sheath is expelled by way of the injected grouting material so that corrosion of the cable is stopped and further corrosion prevented. The grouting material also bonds to the cable and the sheath thereby preventing a sudden eruption of the cable from the surrounding building structure should the cable break.