Trade Journals for the Concrete Industry

For decades, mechanically stabilized earth (MSE) retaining wall structures have been constructed from concrete facing blocks and geosynthetic soil reinforcement. These structures are economical, easy to install, and often the preferred wall for a wide variety of projects. Originally, the concrete facing blocks were smaller, dry cast concrete units, often referred to as segmental retaining wall (SRW) units. SRW units are made on concrete block machines with very low slump concrete. SRW units typically weigh between 60 and 120 pounds each and are set by hand. Over the last several years, large, wet-cast concrete blocks, often referred to as precast modular block (PMB) units, have been used on an ever increasing percentage of MSE retaining walls. PMB units are individually cast from freshly mixed, air-entrained concrete with a typical slump between 3 and 5 inches and a minimum 28 day compressive strength of 4,000 pounds per square inch. PMB units can weigh between 400 and 10,000 pounds each and are set with heavy construction equipment.