Everything You Need to Know About Clay Pavers & How to Choose the Best Type for Your Project.

Clay pavers offer many advantages over other paving solutions for landscape projects. They “add character, charm and value,” The Belden Brick Company. Clay pavers offer a huge opportunity for creative design with a blend of color, texture and pattern. The nearly endless design possibilities, allow architects and landscape architects to compliment the building through enhancing the site.

Clay pavers are a color fast and sustainable material that provides longevity and low maintenance aesthetics to a project. Clay pavers can vary from heavy vehicular, pedestrian and light traffic to permeable, ADA paving. Natural stone varieties can also be fabricated for flooring to provide ranges of color and finishes to assist in slip resistance and compliance codes.

Standard Clay Pavers

All standard clay pavers (those that fall into the ASTM C902 category) have a high compressive strength of 8,000 psi, making them incredibly strong and durable. To put this in perspective, 8,000 psi is about 3x stronger than concrete; and pavers do not require any curing time. In the unlikely event that a single paver or group of clay pavers needs to be replaced, they can be replaced individually so that the look remains the same. If a patch of asphalt covering a similar area needed to be replaced, the new asphalt would be noticeably different compared to the existing asphalt surrounding it. Photo above courtesy of Whitacre Greer.

Standard clay pavers fall into one of three classes for abrasion, meaning how frequently they will be tread upon by pedestrians, bicycles and vehicles.

• Type I — For locations subject to extensive abrasion such as sidewalks or driveways.
• Type II — For locations subjected to intermediate abrasion such as heavily traveled sidewalks and driveways.
• Type III — For locations subjected to low abrasion such as floors or patios in residential homes.

Weather also plays a factor when selecting the correct clay pavers for your project. There are three types of weather classifications for clay pavers including:

• Class SX — For use where pavers may be subject to freezing temperatures below 32 degrees Fahrenheit, while saturated with water.
• Class MX — For exterior use in locations where temperatures will remain above 32 degrees Fahrenheit.
• Class NX — For interior use in locations where the pavers are protected from freezing when wet conditions.

Vehicular Clay Pavers

There are two types of clay pavers that fall into vehicular category, those that meet ASTM C902 (standard pavers) and those that meet ASTM C1272. ‘Pedestrian and light traffic’ pavers are suitable for applications such as driveways and pedestrian sidewalks, where a low volume of vehicles may be driving over them but not parked (ASTM C902). These clay pavers have the same 8,000 psi but need to be set on a bed of concrete. Clay pavers that are designed to be set on mortar, concrete or asphalt are classified as Type R, and are required to have a minimum thickness of 2 1/4 inches thick. Photo above provided by Endicott Clay.

‘Heavy Vehicular’ clay pavers are suitable for applications such as commercial high traffic streets, commercial driveways and even aircraft taxis (ASTM C1272). The durability of these clay pavers makes them an ideal choice for parking areas, entryways and exits as they will be much less prone to cracking than asphalt or concrete in the same type of application. ?The ASTM C1272 vehicular clay pavers have an even higher compressive strength at 10,000 psi and are set on sand instead of concrete.?Clay pavers that are designed to be set on sand are classified as Type F and are required to have a minimum thickness of 2 5/8 inches thick. Photo below courtesy of The Belden Brick Company.

Heavy vehicular clay pavers also fall into three applications:

• PS — Pavers intended for general use.
• PX — Pavers intended for use where dimensional tolerances, warpage, and chippage are limited.
• PA — Pavers intended to produce characteristic architectural effects resulting from non-uniformity in size, color, and texture.

ADA Pavers

ADA clay pavers have a textured surface that provides additional traction beyond standard clay pavers. This texture serves as a means of way finding guidance for pedestrians and wheelchair operators. They are used as ‘detectable warning surfaces,’ which indicate grade changes such as a ramp, stair or a sudden drop in surface elevation. They can also indicate the approach of a street crossing, the edge of transit platform or parking area. Detectable warning surfaces are necessary (and in many cases required by building code) to assist occupants with vision impairment. We recommend cross referencing your local and state building code to determine if ADA clay pavers are required for your application. Photo above courtesy of Endicott Clay.

Permeable Clay Pavers

Permeable clay pavers are actually clay pavers that are set on a bed of aggregate (crushed stone), an open-graded aggregate base, and an open-graded sub-base. Essentially, it is the system, not the pavers that make the paved area permeable. Permeable paving systems offer environmental protection and storm water management. They are an effective method of meeting stringent stormwater management requirements because they reduce and often eliminate the need for storm sewers, culverts and detention ponds. This results in more available land area for buildings and other structures. Photo courtesy of Whitacre Greer

The highly permeable aggregate that fills the joints is what gives the pavement surface as a whole its permeability, rather than the shape of the clay paver. In permeable pavements, spacers (lugs on clay pavers are larger to maintain a uniform joint width of 1/4 in. or wider. In contrast, pavements made with a sand setting bed have sand- filled joints as narrow as 1/16 in. The joint fill aggregate for permeable pavements is open-graded for high permeability, with particles small enough to fit into the paver joints but large enough to meet filter criteria with the underlying setting bed aggregate.

Permeable clay paving systems offer number benefits that make this one of the most environmentally friendly paving systems available. These benefits include:

• Improved health of trees and shrubs by allowing air and water to reach the roots easily.
• Any potential damage to aquatic life from runoff is minimized, as permeable paving systems do not increase the temperature of the runoff.
• Low runoff coefficient, which is the percentage of the total rainfall that will become runoff.
• Water quality improves as oil from vehicles, the most generic pollutant originating on city pavements, is dissipated. Oil that enters through the surface clings to the aggregate particles. It then migrates slowly down and has an extended residence time in the pavement structure. Naturally occurring microorganisms ingest the oil and biodegrade it, thereby reducing the oil’s hydrocarbons to their simpler chemical constituents. Exfiltration of water from the base and sub-base reservoir into the sub-grade soil reduces the total volume of runoff, eases the loads on city sewers and stream channels, further improves water quality in the soil, and replenishes groundwater aquifers with clean water.

The requirements for every project are unique. If you have questions on the information contained in this article, please contact a specialist at Upchurch Kimbrough. Our highly knowledgeable team has the technical expertise to help guide you in your selection process.