Commonly called "rod busters" or "ironworkers," workers who place reinforcing steel have one of the most physically demanding jobs in the industry.
Reinforcing bar supports are made of steel wire, precast concrete, or plastic. There are four classes of bar supports based on the degree of protection provided against corrosion.
While all-plastic supports are not subject to rusting, they must be designed so that they do not crack under loading or when used in cold weather.
Chairs and supports are available in various heights (usually 1/4 inch) to support specific reinforcing bar size, and prices vary for each category and material. Supports also are used to support post tensioning cables in the dropped position. In general, plastic accessories are less expensive than metal supports, and prices will vary depending upon the quantity, region, and supplier.
To meet the specification for concrete cover, it is not enough to simply place the bars on supports. Reinforcing steel must be secured to prevent displacement during construction activities and concrete placement.
A variety of tie types (ties are basically wire twists for connecting intersecting bars), from snap or single ties to saddle ties, is used in the concrete reinforcing industry.
Industry rules for proper installation of reinforcing steel are found in CRSI's MSP.
Probably the newest tool to hit the rebar placing profession is the tie gun.
Plastics are growing as the material of choice for bar supports. Plastic supports can equal or exceed the strength of traditional concrete dobies. Tilt-up and precast panels typically use all-plastic supports.
Reinforced concrete project drawings are not simple to decipher, and specifications are getting even more specific. Installation requirements for highway work are much more stringent.
Everyone agreed that rod busting is the toughest trade in construction today. The reinforcing steel installation trade shares the serious shortage of trained workers presently experienced by the concrete construction industry as a whole. Given the opportunity, most rod busters will move on to less physically punishing construction trades.