A combination of abrasive and high-pressure water was used to prepare the concrete. |
The project's specifications, prepared by Black and Veatch, required the contractor to install a mock-up of the lining system prior to the final application. The ultimate goal of this step was to demonstrate the compatibility of the chosen lining system with the actual concrete comprising the structure. In compliance with this specification, Bryan Painting personnel prepared a random section of the concrete and applied the epoxy resurfacing material, a material designed to bring deteriorated concrete back to its original thickness prior to coating.
The next step was to perform an in-field adhesion test, known as "ASTM D7234 - 05 Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers," which determines the bond strength, (in pounds per square inch) of the resurfacing material in relation to the prepared concrete. In this case, the values obtained approached 500-lbs/in2 , meaning cohesive failure occurred within the concrete. In other words, the bond of the epoxy resurfacer was greater than the tensile strength of the concrete, which is the best result that can be obtained.
Following a successful mockup, the contractor was ready to proceed. Good surface preparation is essential for any protective coating application. In addition to removing all weak and chemically attacked concrete, the surface preparation procedure must provide a good "anchor profile" for application of the lining system.
The contractor on this project quickly realized that the amount of dust generated from the abrasive blasting was not compatible with coating. To overcome this challenge the project team employed a combination of abrasive and water, which dramatically reduced dusting and provided the required surface profile.