Coatings for Concrete
Introduction
Concrete is our most common building material. It’s found everywhere from highway bridges to skyscrapers to swimming pools, protecting these structures from costly and time consuming repairs, if not outright catastrophic failure. While this versatile material seemingly lasts forever, it nevertheless is subject to degradation from water, pollutants, chemicals and even microbes. As an example, heaving and spalled concrete is a common sight resulting from freeze-thaw cycles and bombardment from deicers in harsh winter climates. Unlike carbon steel, concrete is a relatively porous and non-uniform material. Its composition is more varied than steel – it’s just the nature of the product. As a result, in many cases it requires a protective coating.
Madison has had a long history of coating concrete. Concrete coatings vary substantially in composition and performance capabilities. We have focused therefore on areas complementary to our traditional strength in infrastructure coatings. Our polyurethane and epoxy coatings have been used in applications including: storage tanks, containing everything from potable water to industrial chemicals, pipelines transporting a variety of materials including sewage, wastewater treatment facilities, manholes, lift stations, and even marine aquaria.
A Note About Surface Preparation
We mentioned earlier that concrete is a relatively porous and non-uniform material. As a result, surface preparation is critical. Most commonly, a light abrasive blast is used to remove chemicals used in the casting process and byproducts such as laitance and efflorescence. It cleans-out bugholes and leaves an angular surface profile. For many applications, particularly those that involve immersion or even intermittent fluid contact, a seal coat is also recommended. A common phenomenon with concrete is off-gassing and blister formation, often caused by the displacement of air from pores during solvent flash off. adison has two products that help prevent this problem, namely MG201 and MG220. These are easy to use mix-and-apply 100% solids epoxy-polyurethane hybrid coatings that flow into the profile, seal micro cracks and pores and provide an anchor for a variety of Madison topcoats. MG220 is more bodied than MG201 and is the preferred choice where higher build and resistance to slumping on vertical surfaces is required. Within four to six hours they are ready to accept topcoats, and can be topcoated up to 48 hours later. We encourage you to contact us if you have any questions about surface preparation. For the purposes of the following discussion, we will assume that surfaces have initially been sealed with either MG201 or MG220.
Atmospheric Service
For atmospheric service, a number of formats and systems are used, depending on the industry and the anticipated service conditions.
In many applications, a single coat of aliphatic polyurethane will provide the desired service life. Our AcrylaThane line is recommended for moderate duty. For fast turnaround and more severe service, consider our plural component aliphatic product, Tufsheen II. For maximum service life, start with a plural component aromatic product from our CorroCote line and, if UV stability is a priority, finish with an aliphatic topcoat.
Embedded and Immersion Service
For embedded and immersion service, there is a wide variety of choices. Check out the various products in our CorroCote line. Some are plural component, instant-setting: CorroCote II Classic, CorroCote II Plus, CorroCote II Ultra and CorroCote II PW (NSF 61 listed for potable water use) are examples. Others are Mix-and-Apply products, such as CorroCote ‘S’, a paint-like polyurethane
Application and Performance Advantages
Madison product ranges are very broad and, as such, offer a wide array of choices in terms of both application characteristics and performance attributes.
Some of the leading edge handling characteristics you can expect include (1):
Important performance advantages include:
(1) Not all the above features apply to every product