The preparation of concrete for repair is a critical step in ensuring that the repair material adheres securely and lasts. There are several methods for preparing concrete surfaces, such as scarification, brushing or grinding, abrasive blasting, shot blasting and flame cleaning. Dust and debris produced as a result of surface preparation must be removed before applying the surface treatment. The International Institute for Concrete Repair provides molded rubber comparator chips that replicate ten degrees of surface roughness and are designed for direct visual and tactile comparison with the concrete surface in question. Before starting concrete repairs, it is important to determine the cause and extent of deterioration of existing concrete.
Damaged materials must be removed so that only solid concrete and reinforcing bars remain. It is also essential to choose repair materials that are compatible with the existing substrate and able to function as needed. The substrate must be prepared, and the repair material should be applied in such a way as to ensure that they are firmly bonded to each other. Surface preparation of the concrete substrate is considered the most crucial step in a concrete repair project. To ensure that surface preparation procedures were followed according to specifications, the tensile strength of the prepared surface is measured prior to application of the repair.
Normal washing with low-pressure water at 15 MPa or washing with high-pressure water at 35 MPa can generally be adopted to clean concrete surfaces that have already been prepared by impacting concrete removal methods. Impact methods such as percussion power tools can cause micro-cracks or bruises in the concrete surface, forming a weak plane that acts as a bond breaker. To assist contractors in carrying out this assessment, the International Concrete Repair Institute has developed reference guidelines for the CSP-a measurement of the average distance from surface peaks to valleys. VicRoads, Standard Specifications, Section 689 suggests that the average adhesion or tensile strength to the concrete substrate at 7 days should not be less than 0.75 MPa, with no individual result being less than 0.65 MPa for the tensile failure mode of the substrate within the existing concrete substrate. A surface retarder is a chemical that is sprayed onto freshly poured concrete to prevent surface hydration from occurring. To make concrete repairs that last, it is essential to prepare the concrete surface properly. This stage of the surface preparation test would verify the tensile bond strength of the repair material and existing host concrete.
You can check the concrete for faulty material by striking it with a hammer and looking for any resulting indents or damage. The most important feature for the coating of materials or floor coverings is the texture of concrete. During the process of concrete shedding and removal, dust and debris must be contained so as not to pose any danger to interested parties. Preparing concrete surfaces for coatings, coatings, stains, or repair materials is a time-consuming task that many contractors reluctantly perform or are tempted to overlook it altogether.
