Four Common Types of Concrete Retaining Walls

Four Common Types of Concrete Retaining Walls

Retaining walls are one of the most basic uses of structural concrete, yet serve an extremely important purpose. The most common retaining wall provides support to a large quantity of soil on a slope, called backfill, minimizing drain-off and erosion. 

There are multiple types of retaining walls, each with their own particular advantages and disadvantages. The benefits of each as wall, along with the purpose and location of the structure, should be considered when deciding on a type of retaining wall and the method that will be used for installation.

Gravity Retaining Wall

Gravity retaining walls are one of the most popular types of retaining walls due to their ease of construction and lack of need for reinforcement. A gravity retaining wall is shaped like a traffic cone on the cross section. A small ledge of concrete is set underneath the ground to increase stability, though this is not always necessary due to the massive weight of a gravity retaining wall. This type of retaining wall is easily scalable up to around 10 feet high and is usually cast onsite, rather than transported whole to the final site.

Semigravity Retaining Wall

A semigravity wall is basically a gravity retaining wall that has been reinforced with tension reinforcing steel. This allows the semigravity retaining wall to be significantly thinner than a gravity retaining wall, while maintaining the same strength. Again, these types of walls require little to no reinforcement, depending on the amount of backfill being supported.

Cantilever Retaining Walls

Cantilever retaining walls are fully reinforced concrete structures. They use considerably less concrete than gravity or semigravity retaining walls due to their shape and reinforcement.  These walls are shaped like a slightly thicker upside down T. The bottom, horizontal section is called a base slab, with the front section that is left exposed called the toe, and the back section that is under the backfill is considered the heel. The upright vertical section is called a stem.

Cantilever retaining walls use much less concrete, but require much more attention to construction and design of the landscape. When well constructed, these walls can be scaled as high as 25 feet and support a substantial amount of backfill. They can be constructed onsite or manufactured in a factory then transported to the site.

Counterfort Retaining Walls

Counterfort retaining walls look extremely similar to cantilever retaining walls. They are also fully reinforced structures. The difference is that counterfort retaining walls have supports that tie the stem to the heel of the base slab at regular intervals along the wall.

These types of walls are best suited to very large projects, including walls that must be greater than 25 feet tall and are out of the range of cantilever walls. The counterforts decrease the pressure exerted on the retaining wall by the large amount of backfill being contained. The counterforts also serve to add some extra weight, which can be extremely important for large projects. Like cantilever walls, these walls can be poured onsite or transported from a manufacturing plant.