Concrete repair is a necessary process for protecting and extending the service life of existing concrete structures. This can be accomplished using a number of different repair methods. However, selecting the right repair method for a given structure is not always an easy task. There are many factors to consider including surface preparation, the structural needs of the structure, and the availability of repair materials. In addition to these structural and material issues, there are also environmental considerations that must be taken into account. Increased concrete repair activities are associated with escalating impacts on the environment and society due to natural resource depletion, CO2 emissions, inert waste production, noise pollution, and user inconveniences.
The most important step in a concrete repair project is to properly prepare the work area. This is done by cleaning the concrete and removing any loose debris that may interfere with the bonding process. A pressure washer or a garden hose with a power nozzle is usually sufficient for this purpose. It is also important to remove any oil or grease that may be present on the concrete surface. Once the area has been cleaned, it should be misted with water to ensure that it is dry before applying any concrete patching material or new concrete.
When repairing cracks in concrete, there are two main objectives: structural bonding and stopping water flow. To achieve a structural bond, epoxy injection can be used. This technique involves injecting an epoxy into the crack, which then welds together the cracks to form a monolithic structure. This can be performed on both dormant and active cracks.
To stop water flow, a urethane sealant can be applied to the crack. This technique is not recommended for use on wet cracks, however, as moisture tolerant epoxies can be used for wet cracks.
Whether a repair is being made to a slab or a cracked concrete section, a good quality concrete repair product should be selected. Using the wrong material for a given project is the most common reason for failure of a concrete repair. ICRI’s Fuller advises contractors to determine what characteristics they need from a repair material and talk to the manufacturer to get expert insight into how those characteristics can be best achieved with their specific products.
Another important consideration is the durability of a concrete repair product. This includes the physical properties such as drying shrinkage, modulus of elasticity, and permeability, as well as chemical and freeze-thaw durability. Increasing attention is being placed on these properties in the concrete industry as a result of the high failure rates of traditional concrete repairs.
Using the right repair material can greatly reduce the need for future repairs. Contractors should consult a product specification sheet to help them select the best mix for their application. Then they should follow the mixing and application instructions carefully to ensure a successful repair. Finally, contractors should skim coat the repaired area with Sakrete Top ‘N Bond to achieve a finished appearance that matches the surrounding concrete.