Concrete is a widely-used building material globally, prized for its durability, strength, and versatility. However, it can suffer from spalling and concrete cancer over time, compromising its integrity and stability.
Concrete spalling is a significant issue that occurs when the surface of concrete flakes, chips, or peels away, revealing the rough surface underneath. This type of damage is typically caused by factors such as corrosion of steel reinforcement bars and chemical damage. When spalling affects load-bearing concrete elements like columns or beams, it can pose a threat to a building’s structural integrity. Moreover, falling concrete debris can cause serious safety hazards. Therefore, it is crucial to address spalling as soon as possible and take measures to prevent further damage.
Concrete cancer is a more severe form of concrete damage, where steel reinforcement rusts and expands, causing the surrounding concrete to crack and disintegrate. Exposure to water and moisture speeds up corrosion, making this damage more common in coastal areas.
Repair and Remediation Techniques
Various repair and remediation techniques are available to address concrete spalling and cancer. Repair techniques include cutting out damaged concrete using a saw or grinder and applying a cementitious repair compound to fill the void. It is essential to treat and protect the underlying steel reinforcement to prevent further corrosion. Electrochemical treatments like cathodic protection, which applies a low-level electrical current to the steel reinforcement to prevent further corrosion, can be effective.
When concrete cancer is severe, it is necessary to employ invasive repair techniques. These include completely removing and replacing the affected concrete elements or reinforcing the existing elements with additional steel reinforcement.
Protection and Prevention Measures
In addition to repair techniques, protection and prevention measures are also essential. This includes the application of trafficable waterproofing membranes to protect the concrete from water and moisture and regular inspection and maintenance to detect and address concrete damage before it becomes severe.
New Technologies and Treatments
Researchers worldwide are exploring new technologies and treatments to address concrete spalling and cancer. One such example is nanotechnology, which is being studied as a means of strengthening and repairing concrete at a microscopic level. Another approach being researched is biotechnology, with the goal of developing self-healing concrete capable of repairing itself over time.
Recommended Processes in Australia
In Australia, the National Construction Code (NCC) and Building Code of Australia (BCA) provide guidance on the recommended processes for repairing spalling concrete in buildings. Specific sections of the NCC and BCA that cover the recommended processes may vary depending on the type of structure and intended use of the structure. Relevant sections may include Part 3.7.2 (Durability), Part 3.7.3 (External Walls).
Concrete cancer is a silent killer of buildings, but it can be stopped. Regular inspection and maintenance, can prevent it from causing significant damage. By staying aware and taking action, building owners can ensure their structures remain safe, strong, and durable for years to come.