Experienced contractors know that documenting the activities of a coating, lining or waterproofing application can be the key to a successful job. The purpose of documentation is twofold:
The first thing that usually comes to mind when people think of profiling concrete to prepare for coating application is sandblasting. Unfortunately, this method may not always be practical. Sandblasting is loud and can create excessive dust so other alternatives are sometimes required.
When applying elastomeric coatings over concrete, abrading the surface is almost always required. This prerequisite to abrading the surface is twofold:1) Remove the “laitance” or weak surface layer of the concrete.
2) Create an anchor profile for the coating to adhere.
The requirement which most coating manufacturers use to measure the roughness of the concrete surface is the Concrete Surface Profile or “CSP”. CSP was developed by the International Coating Repair Institute (ICRI) and is divided into 10 classifications often depicted by molded rubber comparison chips (CSP 1-10) as shown below.
Polyurethanes are used to make products with properties ranging from soft flexible foams such as memory foam mattresses, to rigid foams used for house insulation. They can be made into soft rubber as used for skateboard wheels or into very hard enamels as used in modern automobile paints.
The range of properties can be quite wide, just by changing the chemistry a little, but there's a problem. The traditional chemistry uses materials that have an affinity for water. For applications such as fountains, pond liners, waterproofing, water and waste water tanks, roofing — where long term or constant immersion is an essential requirement — that affinity for water will lead, eventually, to the product swelling or even failing. The reason is in the chemistry, itself. Here’s why.
With so many epoxy, latex, polyurethane, polyaspartic and other type coatings in the market; selecting the appropriate coating to meet your project needs can be challenging. In deciding between a single part or two part coating it is useful to have a basic understanding of curing mechanisms, coating types, and selection protocols to narrow the choices.
Figure 1: Durometer Chart
There are several methods for testing the hardness of a coating. One common test method used in both field and lab settings is ASTM D2240 – Durometer Hardness. According to ASTM International, Durometer Hardness determines indentation hardness of substances classified as thermoplastic elastomers, vulcanized (thermoset) rubber, elastomeric materials, cellular materials, gel-like materials, and some plastics.
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