The success of cement repair depends primarily on the bond between the repair material and the substrate, which in turn is influenced by many factors. Therefore, this article is mainly concerned with the evaluation of the bond between concrete repair materials and concrete substrates, and the ways to enhance it are discussed. This includes increasing the roughness or humidity of the surface, adding fibers, using interfacial agents, and modifying repair materials.
Contractors must consider the purpose of the concrete repair and the structural requirements before selecting a product to use. This will help them avoid using a repair material that won’t stick to the existing concrete and result in failure. One way to test the bond of a repair is to conduct a mock-up or pull test. A simple test involves gluing a metal dolly onto the concrete surface and pulling on it. This will reveal if the repair will hold and provide an indication of the failure psi.
Cement Repair: Solutions for Cracks and Damage
Other things that contractors should think about are the dimensional characteristics of the concrete and the material to be used in the repair. For example, drying shrinkage can debond a repair, so the repair mortar must have similar dimensional properties as the concrete to which it will be attached.
Additionally, the surface of the concrete to which the repair will be made should be rough and free of debris such as dirt or paint. This is because rough surfaces will better adhere to the repair material. Lastly, the chemistry of the repair material is also important. Ideally, the repair material should have a high early strength and be freeze-thaw resistant.
