Coatings for horizontal concrete surfaces such as concrete walkways or garage floors must hold up to very demanding conditions, not the least of which is withstanding foot and vehicle traffic. Other performance criteria include adhesion to a wide variety of concrete and masonry surfaces, chemical resistance and, especially for clear coatings, resistance to water whitening. As a result of the high physical demands on concrete coatings, more costly and labor-intensive two-component (2K) epoxy or polyurethane coatings, either water-based, solvent-based or 100% systems, are still widely used in the market. Therefore, there is a high demand for getting comparable 2K performance with a one-component (1K) water-based system.
One of the most important performance attributes for these coatings is the ability to resist peeling or imprinting after contact with hot tires, often referred to as hot tire pick-up (HTP) resistance. The issue of car tires pulling the coating from the concrete substrate or leaving a tire mark is especially pronounced in 1K waterborne coatings. The development of new and improved 1K waterborne products has been somewhat lagging due to the lack of an industry-wide standardized laboratory test method. Furthermore, real-life exposure testing and field trials can be lengthy, and wide-ranging parameters, including concrete type, concrete preparation, environmental conditions or the types of tires, can have a significant impact on the HTP failure modes. The difficulty of reliably testing HTP is also exemplified by an ASTM International HTP test (ASTM WK14355), which has been in draft form and under development for the last several years.1