Reinforced concrete is a commonly used construction material in Australia. While strong, concrete is however, subject to deterioration over time. This can be caused by porous concrete or insufficient concrete covering the steel reinforcement, resulting in penetration of moisture and salts which erode the reinforcement. Particularly damaging are chlorides – often from sea spray or chemicals - or carbon dioxide from the atmosphere. As the reinforcing steel corrodes, it expands deep inside the concrete resulting in cracks and spalling that decrease the strength of the structural elements. This is known as concrete cancer.
The problem will not rectify itself. If left unrepaired the steel will be exposed to ever more moisture, expediting the problem and resulting in a structurally unsound and dangerous building.