UNVEILING THE REALITY OF “SINGLE-DAY” CONCRETE COATINGS

In the concrete coating industry, quick-curing liquid coatings called polyureas and polyaspartics are well used. Aside from their quick-cure capability, these liquid coatings provide exceptional UV (sunlight), chemical, stain, abrasion and impact resistance. These properties make polyureas and polyaspartics indispensable. But what’s the difference between the two coating types?

While it’s common to hear “polyurea” and “polyaspartic” used interchangeably, these two coatings do differ in both their chemical composition and cure time. “Pure” polyureas (used to coat truck beds, for example) can harden within seconds. Because of this rapid cure rate, specialized equipment (like portable reactors) is typically required. Applicators applying these products to concrete floors need to have something that cures a little slower…something that allows the applicator to use a regular roller or squeegee to manually apply the coating. So chemists went about modifying “pure” polyureas to create slower-curing products called aliphatic polyureas…another name for an aliphatic polyurea is a “polyaspartic”. Although slower curing than a “pure” polyurea, polyaspartics are still considered quick-curing coating types relative to, say, an epoxy or polyurethane.

Though polyurea-polyaspartic coatings possess incredible benefits, they have one significant drawback – they simply aren’t suitable for direct-to-concrete application (ask an architect) and should never serve as a primer coat…especially under medium to high-moisture concrete conditions. The way that a polyurea-polyaspartic cures prevents them from being able to be applied thickly…only thin to moderate coats are possible (a thick coat won’t cure properly). In addition, quick-curing polyurea-polyaspartics cure even quicker when exposed to moisture in the concrete. So quick that they don’t have much time to penetrate and properly bond with the concrete substrate.

As moisture wicks up through porous concrete in a process called moisture-vapor transmission, hydrostatic pressures build, pushing up against the primer coat. The wafer thin, poorly-penetrating coat of a polyurea-polyaspartic will start to peel (delaminate) if these pressures exceed their ability to withstand the upward forces. This is a common problem with systems that use a polyurea-polyaspartic direct-to-concrete!

Of course, contractors using a polyurea-polyaspartic as primer in “one-day” systems will contest this, but their warranties show their hand. All “1-day polyurea” and “1-day polyaspartic” coating systems have warranty exclusions for “moisture-related issues” (like high hydrostatic pressures) in their small print. Many have warranty exclusions to staining!

If the “1-day” guys were so confident in their flooring, why won’t they fully warrant moisture and staining?

How Do Expert Installers Deal with Moisture?

Expert installers circumvent potential moisture issues (and the resulting delamination) by employing a moisture-mitigating epoxy as the primer coat…never a polyurea-polyaspartic direct-to-concrete. They reserve the fast-curing polyaspartic as a final clear topcoats only. Contractors who promise “one-day” applications can’t follow this method of application, because using a slower-curing epoxy would force the installation duration beyond 1 day (to 2). Therefore, during the sales pitch, the “1-day” guys discredit epoxies (because they only have polyurea-polyaspartics at their disposal) and fail to explain that each coating type has its strengths and weaknesses.