Effectively Sealing Porous Pavers

With the rising demand for hardscape installations, the demand for sealing all these paver installations is on the rise as well. Concrete pavers across the country can be quite different depending on the materials that are used. Interlocking paver manufacturers offer a multitude of different colors and paver styles at varying price points.

Saying all pavers are the same is like saying that all sealers are created equal, which is far from true.

Paver Quality Standards

The standards for the manufacturing of concrete interlocking pavers are set forth in the ASTM C936 (American Society for Testing and Materials).  This standard applies to regular “thick” pavers, not the thin pavers that are used as an overlay on pool decks, patios and walkways. Owners, specifiers and contractors, alike, should insist on pavers that meet these standards, with the understanding that often, quality may go hand-in-hand with a higher cost.

This coping is more porous and absorbs the water within seconds.

ICPI (Interlocking Concrete Pavement Institute) is the trade association representing the manufacturers and installers of concrete pavers in the United States and Canada.  Robert Bowers, P. Eng., Director of Engineering for ICPI, recommends that concrete pavers used in the United States should be manufactured to meet or exceed the criteria defined in ASTM C936 Standard Specification for Solid Concrete Interlocking Paving Units.  This standard specifies several requirements including:

  • At the time of delivery to the work site, the average compressive strength of the tested paver shall be 8000 psi or greater.
  • The average absorption of the tested pavers shall be 5 % or less.

Ensure you are thoroughly informed about the quality of pavers that you are purchasing. Some of the potential issues that may result from having pavers installed that do not meet these requirements are:

  • Premature degradation
  • Increased mold/mildew
  • Premature color loss
  • Cracking/chipping

The Challenge of Sealing Porous Pavers

Sealer contractors today are quickly learning that “all pavers are not created equal.”  Historically, a sealer contractor could approach a seal job with a 90% chance that the pavers would require two coats of a film-forming sealer to be properly sealed.  The first coat would soak into the paver, and the second coat would remain on the surface of the paver delivering the desired level of sheen.

Today, however, successful sealer contractors must vary their sealer usage and techniques to account for more differences in paver porosity.  Concrete pavers have pores that are filled up with sealer.  Penetrating sealers fill the pores without forming a film.  Some sealers are designed to fill the pores and then form a film on the surface (i.e., film-forming sealers).

A good porosity field test is to pour some water on the paver.  If the water soaks into the paver immediately, you are dealing with a very porous surface and should treat it accordingly when applying a sealer.  If the water remains on the surface for more than 30 seconds, the pavers are less porous and should be sealed accordingly.

Sealing these pavers can become quite challenging and frustrating for most contractors, not to mention costly with the addition of more sealer that was originally estimated.

Some pavers have different porosity within the paver itself, which requires the applicator to pay attention and vary their spraying and back-rolling techniques.

The Sealing Solution for More Porous Pavers

When color-enhancement is desired (e.g., the “wet look”), which is typically generated with film-forming sealers, there is a cost-effective solution. First, apply a penetrating sealer to act as a concrete densifier on the pavers.  Black Diamond Coatings’ AQUA-X 11 is an excellent water-based, penetrating sealer to consider.  Once that sealer is dry (typically in 10-20 minutes), apply a coat of your preferred Black Diamond Coatings’ color-enhancing sealer to provide the desired look (e.g., SG+).  Do not mix the use of a solvent-based sealer and a water-based sealer during this process.

This approach will significantly reduce the overall amount of sealer that is needed to properly seal the paver.  In addition, it will reduce the total amount of time on the jobsite by not having to apply multiple coats of sealer to the paver.  In the end, it saves time and money, thus increasing overall job profitability and sealer duration.

The Challenge of Sealing Dense Pavers

Just as there are challenges sealing porous pavers, the same is true in sealing very dense pavers.  Often pavers manufactured for commercial applications, manufactured stone and most wetcast pavers are very dense and should be approached with a similar sealing method to sealing natural stone.

Even those these types of pavers are cementitious, they will not withstand the same sealing applications of their “regular” paver cousins.  Sealing dense pavers using the same high-solids sealer and application methods as a regular interlocking paver will cause adverse issues such as excess sealer on the surface (may increase the slip co-efficiency of the surface), while also increasing the likelihood of adherence issues.

The Sealing Solution for Dense Pavers

Just as a very dense paver will not absorb much moisture, the same is true when applying sealer.  One major factor to consider when sealing a dense paver is making sure that you choose the appropriate sealer to match the surface being sealed. For many sealers, the key to successfully sealing very dense pavers is remembering “less is more.”

Treat the surface as though it was a natural stone sealing job, whether it’s using a stone sealer or one coat of a traditional concrete film forming sealer, or using the stone sealing techniques and application methods.  Ask your sealer manufacturer what to use and how to apply.

The days of approaching every seal job with the same product and application methods are over.  The paver landscape is evolving and so must those of us sealing pavers. Make sure you consider the porosity of the pavers you are sealing and it will make your job much easier, less expensive and you will have a beautifully sealed paver surface for years to come.

To learn more, visit www.BlackDiamondCoatings.com, or call at 800-270-4050.

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