Concrete cancer refers to concrete spalling and cracking problems caused by rebar corrosion in buildings and concrete structures.
When concrete spalling or cracking is noticed in areas such as concrete balconies, building facades, bridges or wharf structures, it is prudent to arrange for a diagnostic analysis by a qualified engineer to identify the cause of the problem and to implement the correct rectification solution.
Poor workmanship during construction, low concrete cover to reinforcement, ingress of carbon dioxide to the rebar level causing corrosion due to concrete carbonation, or ingress of chloride into the concrete causing reinforcement corrosion are some of the causes of concrete cancer, indicated initially by concrete spalling and cracking.
Seeking a professional opinion is important as free advice from a handy man, repair contractor or a repair materials supplier is unlikely to deliver the right solution in most cases. The bulk of the repair cost is related to access and labour. Applying the wrong specification and the wrong material could be a costly exercise and may not deliver the required long term treatment for the structure.
Two main types of treatment are recommended for rectifying concrete cancer. If the problem is related to concrete carbonation and low concrete cover, the repair solution involves the implementation of a polymer modified repair system, which includes repair to all spalled areas by removing the concrete behind the rebars and cleaning the steel to a bright metal condition, followed by the application of steel primer and a polymer modified material, and an anti-carbonation protective coating to the entire concrete area.
For problems associated with chloride contamination of the concrete, which is a common problem for structures and buildings located near coastal areas, the rectification process is more complex and may involve special concrete repair solutions incorporating electrochemical treatment such as cathodic protection.
The real challenge in repairing concrete cancer lies in developing a comprehensive structure-specific strategy for the rehabilitation process, which must be based on true understanding of the problem in each part of the structure. It will involve the development of tailored solutions, undertaking of trial repairs to verify these solutions and the preparation of a detailed specification, which will deliver the most cost effective and technically sound treatment. A more comprehensive approach to developing adequate and proven solutions for the structure will therefore lead to less contract variations, avoidance of long delays, elimination of disputes and reduction of unnecessary and costly work.
Remedial Technology Pty Ltd provides initial professional free advice with relation to all concrete cancer problems.