Brick/Concrete Unit Pavers

 

 

 

 

 

 

 

 

 

 

 

Clay Brick and Concrete Unit Pavement are commonly used as paving materials, and are similar enough in form and function that they are often interchangeable. Known for being highly durable, the small, modular paving units can be arranged in a variety of patterns to create texture, movement, and energy in the landscape. Available in an assortment of natural or engineered colors and textures, unit pavement can complement a variety of architectural and site features for aesthetic interest and harmony.

PROS & CONS

Advantages:

-Because brick/unit pavement is composed of small, regular modules, the installer has a considerable degree of control over where surface jointing will occur.

-Jointing can reflect a variety of regular or irregular geometric patterns, depending on the desired aesthetic and the type of paver selected. Also available in extra long or interlocking shapes, allowing the designer to create a sense of movement/direction with the paving material.

-The designer has a considerable palette of natural and engineered colors from which to choose.

-Highly durable, commonly specified at 8000 PSI compressive strength and above.

-A decorative, durable, intermediate-grade finish material

Disadvantages:

-Depending on the application, a concrete base slab may be required to support the surface pavement, adding considerable site preparation work and material requirements.

-Brick and/or CUP pavement may require a small bond breaker if placed on a concrete slab, to avoid surface cracks appearing above joints in the slab below.

-Usually more expensive to install than concrete or asphalt pavement, due to the base material cost and labor required for installation.

-When using brick: some types of cast bricks may be irregular, with tolerances as much as 5/8” depending on the type. Some of these joints may be too wide to be used in ADA-compliant accessible walkways.

-Best suited for square or rectangular spaces. For paved areas with an irregular shape, pavers may need to be sawcut to fit; this can add significant time and expense to a project, and the quality of the workmanship will be visible at the edges.

 

CONSTRUCTION

The sequence of construction is usually as follows:

EXCAVATION/GRADING

As a first step, the area to be paved will be excavated to allow for a proper building surface to be constructed beneath the pavement. Depending on the pavement’s intended use, the depth and bearing capacity of the base material will vary. Brick or concrete unit pavement designed to receive vehicle traffic (“heavy duty”) will usually require at least an 8” concrete slab below the pavement, with a 12” aggregate base below that. A pedestrian-only surface can be installed on as little as 8” below of crushed stone if the ground below is sufficiently compacted. If you are unsure, a landscape architect or civil engineer can make a recommendation for your project taking into account specific attributes of your site.

Once the excavation is completed to attain the necessary depth, the exposed earth surface below is compacted, usually to a minimum of 95% Proctor Density, or an engineer’s recommendations.

AGGREGATE BASE

Once grading and subgrade preparation is complete, a base course will be laid to provide a stable platform for the pavement profile above to rest on. In most cases, a dense-graded aggregate will be used, since the range of particle sizes can lock together to form a very supportive aggregate base. For applications with permeable joints between unit pavers, an open-graded aggregate or crushed stone will be specified instead, to allow for free drainage below the pavement. The base is distributed over the compacted subgrade in the area to be paved, and is then mechanically compacted itself, either by a steamroller or manual vibrating plate compactor (for smaller areas).

Once the base course is in place, the pavement can be installed.

POUR CONCRETE (IF NEEDED)

If unit pavement is to be placed on a concrete slab, the formwork for the base slab should be constructed to create a container in the desired shape. Some applications may call for a reinforced concrete base, which will require that rebar or welded wire mesh be installed before pouring the concrete. Then, the concrete should be poured into the form(s) to achieve the desired thickness above the aggregate base. Expansion and contraction joints should be installed with the pouring of the concrete base slab, and a bond breaker (usually construction felt) should be provided for in case it is needed later to prevent cracking. Usually expansion joints in the base slab should be no greater than 30’ apart. As this concrete is not the finished pavement surface, it does not require any particular type of finish, although a rougher surface may help give the mortar more to adhere to when the pavers are installed above.

INSTALL UNIT PAVEMENT

The brick or unit pavement can now be mortared to the concrete base slab, or placed directly on the compacted stone base. If unsure what your pattern will look like and you’d like to test it out, the pavers can be laid out on the prepared base material with no mortar and field adjustments can be made to be sure it looks as intended.

When installing brick or other unit pavement, mortar should be applied to the concrete base, with the pavers then being set into the mortar bed. Mortar should then be added to fill in the joints between the pavers, using the appropriate masonry tools to clean up any excess along the way.

Types of Patterns

The herringbone pattern is commonly used by designers in both pedestrian and vehicular pavement applications; its multidirectional arrangement offers a neutral aesthetic, while the interlocking of perpendicular pavers performs well under the wear and tear of vehicles driving over the surface. There are a number of other common patterns as well:

 

 

 

 

 

 

 

 

 

 

 

 

 

Note that the terms “stretcher bond” and “running bond” are used interchangeably. Additionally, there are various other types of “bond” patterns, usually associated with the masonry construction of a particular style or country of origin:

 

 

 

 

 

 

 

As a “warm” paving material, many designers will also mix brick (or concrete unit pavers) with other paving materials for heightened contrast and visual interest.

 

 

 

 

 

 

 

 

 

 

 

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