Retaining Walls Information
Retaining walls are used to retain earth, prevent erosion, and create level surfaces in sloping areas.
Types of Retaining Walls
Product types include poured concrete walls, gravity walls, cantilever retaining walls, gravity poured walls, gabions, crib retaining walls, welded wire walls, plantable walls, and pre-cast walls.
Specifications for retaining walls include materials of construction and dimensions. With concrete block walls, block shape and block texture are also important considerations. Compressive strength, percent air entrained by volume, and the use of rebar or other reinforcements are also important to consider when selecting these retaining walls.
Typically, poured concrete retaining walls are stronger than concrete block walls. There are two basic types: reinforced and non-reinforced. Reinforced concrete retaining walls contain rebar, thin wire truss, or some other form of reinforcing steel. The strength of the poured concrete is directly proportional to the retaining wall’s cross-sectional area. Pre-cast concrete walls are also available. With these retaining walls, the concrete is cast in a mold or form, cured in a controlled environment, and then transported to the work site or job site. The Portland Cement Association (PCA) publishes standards for the design and use of such concrete mixtures. Gravity retaining walls are thicker at their base than at the top. By design, the weight of interlocking building materials such as bricks or concrete blocks is greater than the force of the earth behind the wall. Gravity walls are also defined by battering, a characteristic where the front of the wall appears taller as it eventually moves backwards. Cantilever walls are retaining walls that feature a uniform thickness. They are tied to a footing and designed to hold back significant amounts of earth. With cantilever retaining walls, the footing is designed to resist tipping and sliding forces. Structural engineers select and install steel reinforcements in both the footer and the wall itself. Counterfort retaining walls are similar to cantilever walls, but feature a triangular design that connects the back of the footer to the top of the wall. Poured concrete counterfort retaining walls have inside support sections that provide additional strength. Buttressed retaining walls are similar to counterfort walls, but locate the support structure on the outside of the retaining wall.