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The Attributes and Handlings of Clay Brick
A Comprehensive Look At Brick Use



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These clay pavers, featured at a streetscape in Charleston, South Carolina, and manufactured by Old Carolina Brick company (see below), are laid in a 1-to-1 herringbone pattern, albeit in varying sizes and colors.


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To manufacture their bricks, they use North Carolina shale clay that is hand rolled in sand. This mixture is then forcefully flung into a wooden mold. The sand helps allow the brick to release from the mold, as well as adds texture and controls color. Hand making bricks this way can add a touch of uniqueness; as finger marks, distinctive folds and other surface irregularities distinguish the bricks from conventional machine pressed bricks.



Brickwork is a timeless profession, highlighted by many of the world's oldest and still-standing buildings being constructed out of bricks. This building material offers an architecturally sound and convenient way of building structures, as it is an inherent building block by design.

During the industrial revolution in the beginning of the 19th century, bricks began to be mass-produced. Due to this, bricks were routinely offered in only one color, one shape - red and rectangular - and one size. However, brick manufacturing has made leaps and bounds since, and the myth that bricks are homogeneous is a thing of the past.

Nowadays, there are a vast amount of varying brick shapes, sizes and colors for every project. There are even custom, hand-made bricks that are available from some companies like the Belden Brick Company.

The contents of this article are aimed at providing general, as well as specific, information regarding the aspects of clay bricks and clay pavers. Dimensions, manufacturing, bond patterns, best practices, and safety are all included within.



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The backyard of this Louisiana home underwent a complete renovation. Mullin Landscape Associates, of Harahan, Louisiana, used 12" x 24" true blue flagstone slabs for the decking of the pool, in addition to old style bricks laid in a common bond or American bond pattern. The materials for this project were chosen due to their "traditional New Orleans" qualities.


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The bricks for the stair's treads are laid in a stack bond, which has bricks laying side by side, front to back, without staggering. Their orientation is known as "rowlock," meaning they are on their sides. Bricks laid in the "stretcher" position can be seen as the risers. The bricks for the walkway and the fireplace are laid in a common bond pattern.



Sizing, Manufacturing and Strengths
To start, the standard brick weighs approximately 4.5 lbs. and has the dimensions 3-5/8"x2-1/4"x8". After the clay and water are mixed, molded, and textured and dyed if needed, the last process of manufacturing is kilning them. The temperature inside these kilns is usually around 2,000 degrees Fahrenheit, but according to a study conducted by Ambo University in Ethipoia, "as the optimum firing temperature [of the kiln] increases, the compression strength of the fired clay bricks increases..."

This process is done for standard sized bricks, as well as the various other sizes - of which there are ten, according to Archtoolbox.com, an online reference site with information on construction. Their website provides these ten different sizes: standard, modular, norman, roman, jumbo, economy, engineer, king, queen and utility. Each of the sizes is accompanied by a suggestion on the total vertical course, or row, height that an unreinforced structure can be safely built. For example, the site allows that engineer (3-5/8"x2-13/16"x7-5/8"), king (2-3/4"x2-5/8"x9-5/8") and queen (2-3/4"x2-3/4"x7-5/8") sized bricks be built 5 courses high, or about 16 inches, before reinforcements should be put in.

In regards to compression strengths, one of the leading authorities on clay bricks, the Brick Industry Association (BIA), states "Brick unit compressive strengths range from 1,700 psi to 36,000 psi, with a mean value of over 5,200 psi for molded brick and over 11,300 psi for extruded brick. Brick unit strength is directly related to compressive strength of the brick masonry assembly."

The BIA also describes the two types of clay brick, solid units and hollow units. They suggest using hollow units for reinforced brick bearing walls because they have interior cells that can accommodate vertical reinforcement and grout.

According to Quikrete, an American building material manufacturing company, solid units are suitable for use in small walls that don't exceed 3 feet in height. Their Basic Brick Construction guide reads, "A wall that is built in two wythes or tiers can be safely built up to 3 feet; for a wall above 3 feet, steel reinforcement is required."

Two options for reinforcing a small brick structure are supplied in the guide; either metal rods inserted into the grout after it has slightly stiffened, or ties that are laid across two wythes.

Brick Patterns
When laying bricks for any project, the pattern is crucial. For walls and structures, the aforementioned building materials manufacturer relates that the most typical brick pattern is the common or American bond pattern. This pattern is made by staggering the bricks in a way that each brick has two bricks above and below it.

Walton & Sons Masonry Inc. provides five other typical brick bond patterns for structures: running, English, Dutch, Flemish and stack bonds. They also mention, "vertically staggered bonds tend to be somewhat stronger and less prone to major cracking than a non-staggered bond."



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This patio and party house incorporate full sized clay pavers from Pine Hall Brick placed on top of an existing concrete foundation. The clay pavers for the patio are arranged in a basket weave pattern, which features bricks laid in pairs in a checkerboard arrangement. These 4"x8"x2.22" thick pavers are wire cut to have a square edge. According to a study conducted by the Bishop Materials Laboratory at Clemson University, when submerged in cold water for 24 hours, these pavers absorbed an average of 5% of the water. The study also found that they are able to withstand an average of 18,247 psi.


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The driveway of this private residence uses Belcrest 350 modular pink bricks, manufactured by the Belden Brick Company. A test report conducted by Clemson University showed that this specific type of clay brick is able to withstand compression pressures of 11,863 pounds per square inch, making it a fairly strong choice for a driveway. The texture is Sand Mold and each brick is 3-5/8"x2-1/4"x7-5/8" - these dimensions are for the brick size called modular.



Shape
In terms of shape, bricks have undoubtedly evolved from the generic rectangular cubes that were mass-produced in the 1800s. Today, clay bricks are available in dozens of different shapes and sizes. For instance, Ibstock plc, an English brick manufacturer, catalogs the following brick shapes: angle, cant, bonding, bullnose, arch, sill, capping, plinth, radial, shelf angle, soldier, spiral, and universal joint. Their website, www.ibstockplc.com, provides dimensions, variations, real world applications and pictures for each shape of brick listed.

In the instance that a brick needs to be cut in order to fit, it can easily be cut with a brick chisel and brick hammer. For a finer cut, use the brick chisel and gently tap it with a hammer until the brick breaks. For a rougher cut, just use the brick hammer and carefully strike the brick. Masonry saws are perhaps the best option for cutting bricks, although they are more costly than the hand tools.

Even if none of these shapes can accommodate your task, a few manufacturers, are able to hand shape one-of-a-kind specialty bricks that can suit a project's specific requirements.

Mortar
The BIA reports that when choosing a mortar, "Portland cement-lime mortars with an air content less than 12 percent are recommended for their superior bond strength and resistance to water penetration."

Common practice is to use a 1/2 " mortar joint between each standard sized clay brick. An important thing to remember when constructing small walls of brick is to start at the ends and work inwards - always making sure your bricks are level during the entire process.



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This hardscape, located at an elementary school in Philadelphia, effectively transformed a predominately paved, non-porous schoolyard into a more sustainable landscape with over 5,500 square feet of permeable clay pavers that efficiently manage stormwater from both the schoolyard and the public street. The project also involved planting 3,000 perennials, 35 shrubs and 19 trees. ThinkGreen LLC of Pennsylvania was the contractor for this project. The final results accrued two awards: a silver award from the 2017 Bricks in Architecture competition and an inaugural award from the Green Stormwater Infrastructure Partners in 2016.


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Paver tiles and thin pavers are great for placing on top of an existing concrete hardscape. While these pavers are about half the height of a normal brick, 3/8" and 1-3/8" respectively, they are still durable and scratch resistant; making them suitable for indoor or outdoor use that incorporates furniture or sees a lot of foot traffic. A handy tip is to use thin pavers if a door only has 1" ground clearance over the current concrete slab. For this floor in an outdoor living room, thin pavers were installed on top of the existing concrete slab.



Clay Pavers
Essentially, clay pavers are thin bricks that, according to the business manager of Pine Hall Brick, Walt Steele, are designed to be used in two types of applications.

Besides indoor applications, "they can also be used outside as overlays on existing concrete that can't accommodate the height of a full thickness pavers; for instance, on a front porch where the door only has 1" of clearance over the current concrete slab," conveys Steele.

Pavers also come in a range of colors and sizes, just as bricks do. Steele's company offers four thicknesses of clay pavers: 3/8" paver tiles, 1-3/8" thin pavers, 2-1/4" standard pavers and 2-3/4" heavy vehicular pavers.

As for brick paver patterns, the landscapingnetwork.com offers six very common patterns: basket weave, circular, herringbone, European fan and running bond. For installation of clay pavers, the website states, "Although it is common to use mortar, it is not a requirement; you can use gravel, sand, or even types of grasses or moss to fill in between."

More Information
The Brick Industry Association has more than 48 technical guides on working with bricks. There is information on everything from sound installation practices to painting bricks. The association also formed the Brick Industry Association Certified Brick Specialist certification, which recognizes individuals that passed "in-depth technical and sales training on brick." Their website lists the individuals who have passed this course and obtained the certification, which could be a terrific source of contacts for information; and once you become a part of that list, a marketing tool for your company.



As seen in LC/DBM magazine, March 2018.






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November 14, 2018, 6:10 am PST

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