THE REFURBISHMENT AND FUTURE CORROSION PREVENTION OF LARGE CONCRETE GUTTERS USING IMPRESSED CURRENT CATHODIC PROTECTION

摘要

Concrete gutters installed in a public school have suffered extensive deterioration, to the point that delamination/spalling of the white quartz facing and cracking on the inside surface of the concrete gutters are common phenomena, posing a distinct safety hazard to both staff and pupils. Rectification was considered urgent and given a high priority by the Department of Housing and Works. Remediation required that the gutters be either replaced or repaired in situ. Due to the method of original construction and the need to maintain full availability of the school facilities, replacement could only have been carried out during school holiday periods, which would have resulted in a piecemeal construction phase over at least two years. Damage to the roof structure and ceilings during this work would have necessitated additional repairs, resulting in extra expense and temporary loss of facilities. The alternative was to cut out damaged concrete and repair or replace the reinforcement locally, and then install an impressed current cathodic protection system to the affected gutters to prevent progressive damage in the future. This Paper describes some of the problems encountered during construction, and in particular shows the extent of insipient damage discovered during the repair period. The design of the cathodic protection to suit the repairs is detailed, and the eventual outcome demonstrated.