Cathodic corrosion protection of reinforced concrete requires adequate monitoring to be effective. Basic remote monitoring units, developed in the 1980s, have been adapted and refined to handle needs specific to reinforced concrete structures. Sophisticated remote monitoring systems are now available to perform various essential monitoring tasks, collect data and transfer this information to a computer at a remote site.
Corrosion in reinforced concrete steel is increasingly being mitigated by means of cathodic protection. Developed in the 1980s, this type of corrosion protection involves the supply of a cathodic current to the steel reinforcement using a rectifier and an anode. Impressed current cathodic protection, however, requires regular monitoring to ensure adequate corrosion mitigation at all times. Companies considering cathodic protection for their concrete structures must take the following into consideration:
Accessibility of the structures to be protected, whether they are far away or hard to get to. In the case of multiple structures, whether they are spread fm apart. l Whether they possess the qualified personnel to ensure the proper operation of a cathodic protection system for reinforced concrete. Recent advances in the field of electronics have made possible the development of sophisticated remote monitoring systems for the cathodic protection of reinforced concrete. In the ten years since the advent of Remote Monitoring Units (RMUS), these have evolved from units which performed the basic monitoring of rectifier voltage and current to very sophisticated systems capable of monitoring complex corrosion protection set-ups, initiating and monitoring depolarisation cycles, generating alarms corresponding to user-defined conditions, and adjusting rectifier output, all from a remote location.
THE HISTORY OF CATHODIC PROTECTION REMOTE MONITORING
The remote monitoring of cathodic protection rectifiers was first attempted in the 1970s when several companies carried out tests using radio-equipped systems in conjunction with aircraft. This type of system was plagued with technical difficulties and was shelved after many trials. The appearance of affordable microprocessors in the 1980s stimulated the development of cost effective RMUS which could fit in a small enclosure.
The first commercially available remote monitoring system developed specifically for concrete applications was presented by Corexco at NACE Corrosion 89 in Las Vegas. This unit, the CORD-2 is still available but has since been extensively modified. Today, remote monitoring systems adapted for, or specifically developed for, concrete applications are numerous and can be purchased as off-the-shelf units in various configurations from several companies.