Used as permanent formwork for bulkheading thick foundation mats and walls, ribbed expanded metal eliminates the stripping, cleaning and reoiling that is normally required by plywood bulkheads. Though used like other form facing materials (with strongbacks and if necessary walers), ribbed expanded metal differs in that it is simply left in place after the concrete has hardened. Manufactured in sheets, ribbed expanded metal is basically a galvanized steel mesh stiffened with integral ribs.
Ribbed expanded metal sheets can be placed with the ribs positioned horizontally or vertically. When used to form bulkheads in 10- to 20-foot-deep foundation mats, the sheets are generally placed with the ribs horizontal so that the bracing can be oriented vertically. This permits the bracing to be pulled out from the top, like fingers, and reinserted at the next bulkhead location. When used to form bulkheads in walls, the expanded metal sheets are placed with the ribs running vertically so that the number of pieces is minimized. Sometimes the sheets are tied to and supported by the reinforcing steel, thus eliminating the removal of bracing as well as formwork.
In addition to serving as a nonremovable form for construction joints, ribbed expanded metal can also be used as both formwork and reinforcement in horizontal concrete slabs, arched concrete slabs, structural ceilings and curved walls. It is suitable as a heavy-duty lath for plaster or stucco and, in an uncovered state, as a decorative paneling for suspended ceilings. In the construction of curved walls, it is said to reduce costs by simplifying the placement of forms and reinforcement. The sheets are cut to length and curved to the required radius at the factory, ready for installation at the jobsite.