Segmental retaining walls are modular block retaining walls used for vertical grade change applications. The walls are designed and constructed as either gravity retaining walls (conventional) or reinforced soil retaining walls. The system consists of dry-cast concrete units that are placed without mortar (dry stacked) and rely on their unit to unit interface and mass to resist overturning and sliding. Unit to unit interfaces include friction, shear elements, and interlock. The systems may also employ soil reinforcement that extends into the backfill and allows for the construction of walls with significant height (e.g. in excess of 50 ft (15.24 m)) that could not be accomplished with the units alone.
Segmental retaining walls are considered flexible structures, so the footing does not need to be placed below the frost line, provided there is sufficient foundation bearing capacity. SRW units are manufactured in conformance with industry standards and specifi cations to assure that units delivered to a project are uniform in weight, dimensional tolerances, strength, and durability—features not necessarily provided in site cast materials.