Q: Since I began sealing concrete floors years ago, the EPA has adjusted its rules several times. It seems VOC levels for concrete sealers are constantly changing. What do I need to know if I work in different areas?
A: Increasingly strict volatile organic compound (VOC) regulations could mean that your favorite solvent-based concrete sealer used for patios, driveways, pool decks, or sidewalks is no longer available. This is especially true if you work in certain parts of California.
The U.S. EPA defines a VOC very broadly. Basically, any volatile compound of carbon is classified as a VOC for regulatory purposes, unless it is considered exempt. Under the Clean Air Act, the EPA set a national standard for the amount of VOC content allowed in architectural and industrial maintenance coatings.
For concrete sealers, certain states default to the federal EPA mandates while others set their own. To make things even more complicated, some counties and districts within those states determine their own maximum VOC levels. Canada also mandates its own VOC standards.
If you've been in the construction industry for a lengthy time, you know that these regulations are constantly changing, and if you're caught out of compliance it can cost a bundle of money. For instance, in New Jersey, if you are caught transporting a gallon of noncompliant product that is 25% over the regional Ozone Transport Commission (OTC) limit, it will cost you $600. If it's 50% over the limit, it will cost you $1000 per gallon.
In many cases, VOC regulations require that manufacturers modify their formulations to remain in regulatory compliance. Fortunately, no matter how restrictive the regulations in your particular region, there are still both solvent- and water-based formulations available that comply with required VOC levels.
Product choice implications
With so many different regulations, and so many evolving concrete sealer product choices, many contractors have become concerned about the viability and legality of their preferred concrete sealers, especially if they are solvent-based. These sealers have been around a long time, so many contractors have a high comfort level with them. Solvent-based sealers generally have excellent adhesion, good penetration, and high gloss that imparts a darker, wetter appearance preferred in many concrete applications.
Although it is possible to meet VOC regulatory requirements with certain solvent-based concrete sealers, there is a limit to how much more in the way of VOC reduction these products can achieve. As a result, many contractors are investigating the effectiveness of water-based sealers, which, because of their water-based composition, are inherently much lower in VOC content.
Water-based concrete sealers have a long history of good performance, with excellent durability, and chemical- and water-resistant properties. Over the past several years, formulators have also been able to demonstrate strong adhesion properties, an area where previously the products had fallen short. Handling and disposal with water-based sealers is also safer and less complicated than with solvent-based sealers, due to the water-based properties.
The good news is that, for now, contractors still have a choice between solvent- and water-based concrete sealers, even if they operate in the California South Coast air district, where the VOC limit for waterproofing concrete and masonry sealers is 100 grams per liter (g/L)—the lowest standard in the world to date.
Acrylic-based concrete sealers are a good example for ongoing product flexibility. Available in both solvent- and water-based formulations, acrylic-based sealers are widely used for exterior concrete surfaces since they are UV-resistant and provide good resistance against both water and chloride, while also maintaining high adhesion under wet conditions.
While many water-based acrylic sealers have achieved the 100 g/L VOC limit, there are several solvent-based acrylic sealers that comply with this mandate as well. Solvent-based concrete sealers can be made VOC-compliant if formulators replace solvents high in VOC content with ones that are labeled VOC-exempt by the EPA, such as acetone and parachlorobenzotrifluoride (PCBTF).
Adapt and prosper
VOC regulations are becoming more restrictive everywhere and they are only going to get lower. When the South Coast air district in California set its VOC limit for concrete sealers at 100 g/L in 2007, it signaled a downward trend that many jurisdictions have followed. The EPA has been discussing a change in the national standard for several years now, and some jurisdictions are talking about a VOC limit of 50 g/L.
The bottom line is that as VOC regulations tighten, concrete sealer product choices may narrow, and product application and performance properties will change. Getting solvent-based sealers down to 50 g/L will be difficult, so this may be a good time to become familiar with water-based alternatives. In the meantime, remember these tips:
- Make sure you understand the VOC regulations in your area. (Look at the diagram on page 40 and check with your supplier for more detailed information.)
- Check the product label, specification sheet, or Material Safety Data Sheet to verify the VOC levels are in compliance.
Contributed by Dow Construction Chemicals, which combines the capabilities of Rohm and Haas, and Dow Wolff Cellulosics, to offer technical knowledge to manufacturers of building and construction products. Visitwww.dowconstructionchemicals.com.