Corrosion of steel in a concrete structure such as a column in sea water
occurs primarily at the zone which is subject to a wetting and drying
action and is inhibited using cathodic protection by attaching to the
column at the zone an impervious sealed sleeve which carries no anode
itself but which cooperates with an anode body in the water. The sleeve
acts to inhibit permeation of oxygen through the concrete to the steel
and at the same time acts to promote transfer of current from the anode
through the concrete under the sleeve by preventing drying by preventing
moisture escape. An anode arrangement may be provided only at the top of
the sleeve to consume oxygen in that area. The sleeve may be applied over
a layer of grout. The top edge surface of the grout may be sealed from
the sleeve to the column.