Concrete repair is the process of restoring a hardened concrete surface that has lost its ability to hold concrete materials together due to damage or exposure to the environment. Concrete repair is suitable for cracks, physical impacts, chipped surfaces or surface flaking. Cracks are sealed and epoxy is injected to restore strength. When a crack affects the performance of the structure, we then repair it to restore its structural properties.
Epoxy injection is often the basis of this type of repair, with or without added reinforcement. Injected epoxy is actually stronger than concrete and can restore the strength of the concrete, but if there is an underlying problem, such as an overloaded structure or some condition of movement, the concrete will simply crack again elsewhere. The industry recognized that too many concrete repairs were failing too soon. To address this issue, documents were created to provide guidance on how to consistently produce durable concrete repairs.
Understanding what is involved in repairing and restoring concrete and masonry structures is critical, as is being able to identify the warning signs of a minor repair that is on its way to becoming a major investment. The number one way to save money on concrete and masonry repairs is to budget for routine building inspections and ongoing maintenance from the outset. Many types of concrete incorporate some material susceptible to alkali-silica reaction (ASR). Corrosion of steel in concrete can be a major problem for many reinforced concrete structures if moisture is present.
To prevent this, select a repair material that provides the necessary material properties and can be placed by the most appropriate application method. External reinforcement is usually done by bonding some type of flexible reinforcement, such as carbon or glass fibres, to the outside of the concrete element and then covering it with placed concrete, trowelled concrete or shotcrete. The adequacy of thermal expansion coefficients is fundamental to the versatility of reinforced concrete. How long the repair is expected to last must also be considered when choosing the type of repair material to use.
Any large patch or coating made of an impermeable material can trap moisture between the existing concrete surface and the seal made by the repair. Of particular concern today is the reaction of alkali silica in concrete and corrosion of reinforcing steel, both of which are affected by the alkalinity of Portland cement concrete. If the concrete needs to be reinforced, various techniques are used, such as simply increasing the size of the concrete element and external reinforcement. The promise shown by Engineered Cementitious Composite (ECC) offers a potential solution to the global problem of rapidly deteriorating concrete infrastructure.
In conclusion, repairing and restoring concrete and masonry structures requires an understanding of what is involved in order to produce durable repairs that will last for years. Budgeting for routine building inspections and ongoing maintenance from the outset can help save money on costly repairs down the line. Selecting a repair material that provides necessary material properties and can be placed by an appropriate application method can help prevent corrosion and other issues caused by moisture in reinforced concrete structures.