Your crew torch-cut rebar after the pour. What the codes say and what to ask for

Cutting to length is routine. The Concrete Reinforcing Steel Institute's field guidance calls for bolt cutters on uncoated bars up to #5 and an oxy-acetylene torch on #6 and larger, including bars already partly embedded in hardened concrete. CRSI says field cutting comes up when bars arrive too long because of design changes or mistakes in detailing, fabrication or placing. Epoxy-coated bars are the exception: CRSI says to cut the larger sizes with a diamond saw, never a torch, and to coat the cut ends with two-part epoxy.

Heat used to bend a bar is a different matter. ACI 318 does not allow field bending of bars partly embedded in concrete unless the construction documents show it or the licensed design professional permits it, the American Society of Concrete Contractors wrote in For Construction Pros. Where ACI 301 is the project specification, only #3 to #5 bars may be bent cold, and only above 32 F. Larger bars must be preheated to between 1,100 and 1,200 F, and the bar at the concrete face may not exceed 500 F. Under CRSI guidance, only the engineer can approve heating a bar.

Welding falls under AWS D1.4. Common ASTM A615 bar is prone to cracking without enough preheat, STRUCTURE magazine notes, and when mill reports are missing the code sets 300 F preheat for #6 and smaller and 500 F for #7 and larger. Tack welds are generally prohibited unless they meet D1.4.

Ask for the size, coating and location of every cut bar, whether any bar was heated along its length, and the mill certificates. For disputed bends, ASCC describes straightening one or more bars cold and having a lab pull them to failure while they are still in the concrete. If tensile strength meets the spec, the rest can be accepted and replacement bars epoxied in for those broken.