- Deformed bar
- A reinforcing bar rolled with ribs and lugs on its surface so concrete grips it mechanically. These deformations are what make splices, hooks and development lengths work, and they distinguish rebar from smooth wire or dowels.
- Bar designation number
- The whole-number size label on a bar, equal to its nominal diameter in eighths of an inch. Number 4 is a half inch, number 8 is one inch. Weight per foot, hook size, lap length and cost all come from this number.
- Grade 60 steel
- A common strength designation for reinforcing bars, meaning a minimum yield strength of sixty thousand pounds per square inch. The grade is marked on the bar at the mill, and using a lower grade than the plans specify is a substitution that needs authorization.
- Standard hook
- A bent end on a bar, at ninety, one hundred thirty-five or one hundred eighty degrees, with a specified straight tail. It anchors the bar within concrete where straight length is not available, such as at stirrups, footing corners and wall ends.
- Bend diameter
- The minimum diameter of the pin or mandrel around which a bar may be bent, which grows with bar size. Bending too tightly cracks the steel or crushes concrete inside the bend, so fabricators follow the printed minimums instead of improvising.
- Lap splice
- Two bars placed side by side over a specified length and tied so load transfers through the surrounding concrete. Required length depends on bar size, grade and concrete, laps add to the takeoff, and staggering them avoids weak planes.
- Mechanical coupler
- A threaded or swaged sleeve that joins two bars end to end without a long overlap. Couplers save steel and congestion in heavily reinforced sections, but they have to be installed and inspected according to the manufacturer and project requirements.
- Concrete cover
- The thickness of concrete between a bar's surface and the nearest face of the member. It protects steel from corrosion and fire, differs for formed, earth-poured and exposed surfaces, and depends on supports staying in place while concrete is poured.
- Clear spacing
- The open distance between the surfaces of adjacent bars, not center to center. It must be large enough for aggregate to flow through and for consolidation tools to fit, so crowded bars at splices and corners can cause honeycombing.
- Dobie
- A small precast concrete block, often with embedded wire, placed beneath bars to hold them off the soil or forms. Because it is the same material as the slab, it works well in footings and slabs-on-grade where plastic chairs might sink.
- Tie wire
- Soft annealed wire, usually supplied in coils, used to bind crossing bars so they hold position until concrete is placed. The tie does not add structural strength; its job is to keep layout intact. Quantity is figured from bar weight placed.
- Stirrup
- A closed or U-shaped loop of small bar wrapped around the main longitudinal steel in a beam or lintel to resist shear. Spacing is tight near supports, and a ready-bent shape must be checked against the drawings before it is placed.
- Bar mark
- The identifying code, usually a number or letter combination, that links a bar on the placing drawing to its entry on the bar list and to its tag in the yard. Matching marks is how the right bar gets to the right location.
- Dowel template
- A rigid guide, often wood or steel, used to hold starter bars or anchor bolts at their exact plan locations while concrete is placed. Setting templates level, braced and square avoids columns and walls that cannot be built later.
- Epoxy-coated bar
- A reinforcing bar with a fusion-bonded epoxy layer to resist corrosion in bridge decks, marine and deicing exposures. The coating chips easily, so handling uses padded slings, damage is repaired, and tying uses coated wire.
- Mill certificate
- A document from the steel producer that records the heat number, grade, chemistry and test results for a lot of bars. It is how a delivery is matched to the specified grade, and keeping it on file matters when an inspector asks for proof.
- Post-tensioning tendon
- A high-strength steel strand or bundle, usually greased and sheathed, that is placed in a slab or beam in a draped or flat profile and stressed after the concrete gains strength. It compresses the concrete and helps control cracking and deflection.
- Stressing elongation
- The measured stretch of a tendon when the jack pulls it to the target force. Comparing actual to calculated elongation reveals friction, broken wires or slip, and a result outside tolerance has to be reported and resolved.
- Impalement protection cap
- A rigid cover or trough placed over vertical bar ends so a worker who falls or stumbles onto them is not skewered. Plastic mushroom caps alone can fail under impact, so the required type depends on the situation.
- Reinforcing cage
- A prefabricated assembly of vertical bars and ties or spirals, such as for a column or drilled pier, built on the ground and lifted into position. Its weight, balance and stability must be planned, since uncontrolled cages can topple during lifting.
