This chapter covers all operations involved in processing and placing reinforcing bars, from material receiving to final inspection. For the Red Seal exam, you must master not only the technical procedures, but also dimensional tolerances, development length calculation rules, and Canadian standards requirements. The ironworker-reinforcing is responsible for structural compliance: a positioning or lap splice error can compromise the load-bearing capacity of a reinforced concrete element.
1. Receiving, Storage, and Handling of Bars
1.1 Bar Identification According to CSA G30.18
Reinforcing bars in Canada are manufactured in accordance with CSA G30.18 (Steel Bars for Concrete Reinforcement). Each bar carries distinctive markings:
Rolling mark: identifies the manufacturer (e.g., a letter or symbol).
Size designation: bar number (10M, 15M, 20M, 25M, 30M, 35M, 45M, 55M).
Steel type: the letter W indicates a weldable bar (Grade 400W or 500W). The absence of a letter indicates regular Grade 300 steel.
Grade mark: a dot or raised line indicates the grade (e.g., one dot = 400 MPa, two dots = 500 MPa).
Table 1: Nominal Bar Dimensions (CSA G30.18)
Size
Diameter (mm)
Area (mm²)
Mass (kg/m)
10M
11.3
100
0.785
15M
16.0
200
1.570
20M
19.5
300
2.355
25M
25.2
500
3.925
30M
29.9
700
5.495
35M
35.7
1000
7.850
45M
43.7
1500
11.775
55M
55.7
2500
19.625
> Exam Tip: You won't be asked to memorize all diameters, but you must know the relationship between the size (number) and the approximate area. The simple rule: area in mm² ≈ 100 × (number/10)² for sizes 10M to 30M. For 35M and larger, refer to the table.
1.2 Storage
Bars must be stored on cradles or supports (timbers) at least 150 mm off the ground to prevent contamination from soil and moisture.
Separate bars by size, grade, and type (weldable vs. non-weldable) to prevent picking errors.
Protect threaded ends (if applicable) with caps.
Never store steel directly on the ground: surface corrosion (light rust) is acceptable, but deep pitting (loss of cross-section) is cause for rejection.
1.3 Handling
Use slings with edge protection (rubber corners or sleeves) to prevent cutting the slings.
For long bundles, use a spreader bar or lifting beam.
Number of bars per bundle: respect lifting limits (generally 2 tonnes per bundle for a truck, but verify crane capacities).
Safety Rule: never walk under a suspended load; never guide a load with bare hands — use guide ropes.
2. Cutting Reinforcing Bars
2.1 Cutting Equipment
Equipment
Advantages
Disadvantages
Mechanical shear (guillotine)
Fast cutting, clean cut, no heat-affected zone
Limited to diameters ≤ 35M, noisy, blade maintenance
Abrasive cut-off saw
Portable, cuts all diameters
Sparks, consumable discs, risk of burning the steel
Cold saw (with lubrication)
Precise cut, no burrs
Slow, expensive, used for special assemblies
Thermal cutting (oxy-fuel)
For large diameters (55M)
**Not recommended** for reinforcement: alters the mechanical properties of the steel
Golden Rule: Oxy-fuel cutting is prohibited for reinforcing bars intended for reinforced concrete, except with special authorization from the engineer. Heat modifies the steel's microstructure and reduces its ductility.
2.2 Cutting Tolerances
Cut length: ± 25 mm for straight bars (standard tolerance).
For bent bars: the tolerance applies to the total developed length, not to each individual segment.
Ends must be cut at right angles (square): a skew of more than 1.5° is unacceptable.
2.3 Calculating Cut Length (Developed Length)
The cut length (Ld) is the sum of the straight segments plus the length of the bent portions measured on the neutral axis of the bar (centerline).
General Formula:
Ld = Σ (straight segments) + Σ (bent lengths)
For a 90° bend:
Bent length = (π × D / 4) where D is the bend diameter (measured at the bar axis)
For a 180° bend (hook):
Bent length = (π × D / 2)
> Important: The bend diameter D is measured at the inside of the bend (inside diameter) or at the axis depending on the convention used. In Canadian practice, the inside bend diameter (pin diameter) is used, and the bar diameter is added to obtain the diameter at the axis.
Example: 20M bar with a 90° hook (inside bend diameter = 6db = 6 × 19.5 = 117 mm).
Diameter at axis = 117 + 19.5 = 136.5 mm
Bent length = π × 136.5 / 4 = 107.2 mm
2.4 Waste and Optimization
Order bars with a 5% margin for cutting waste.
Optimize cutting plans to minimize offcuts: group similar lengths together.
Offcuts longer than 1 m should be returned to the supplier (credit) or reused if approved.
3. Bending Reinforcing Bars
3.1 Bending Equipment
Mechanical bender (manual or motorized): the most common, used for diameters up to 35M.
Hydraulic bender: for large diameters (45M, 55M) or multiple bends.
Bending table: for complex bends (stirrups, ties, spirals).
3.2 Minimum Bend Diameters (CSA A23.3, Clause 7.2)
CSA A23.3 (Design and Construction of Concrete Structures) imposes minimum bend diameters to prevent steel cracking and concrete failure:
Table 2: Minimum Inside Bend Diameters
Bar Diameter
Minimum Inside Diameter
10M to 20M
6 db (6 × bar diameter)
25M to 30M
8 db
35M to 55M
10 db
Stirrups and ties (all sizes)
4 db (absolute minimum)
> Exception: For stirrups and ties, the minimum inside diameter is 4 db, but never less than 50 mm to facilitate concrete placement.
3.3 Common Bend Types
90° hook (L): used for end anchorages of bars.
135° hook (seismic pin): used for seismic stirrups.
180° hook (J): standard anchorage for tension bars.
Hairpin bend (U): for construction joints.
Spiral bending: for circular columns (constant or variable pitch).
3.4 Bending Tolerances
Bend angle: ± 2° for angles ≤ 90°, ± 3° for angles > 90°.
Bend position relative to the mark: ± 25 mm.
Bends must be made cold (never hot).
Prohibition on straightening a bent bar: a bar that has been bent and then straightened loses its ductility and must be rejected.
3.5 On-Site Bending vs. Shop Bending
In the shop: the majority of bending is done in the factory (prefabricated rebar). Advantages: quality control, precision, productivity.
On-site: reserved for minor adjustments and tie bars. Portable benders are used with caution.
> Exam Trap: Bars bent on-site must meet the same tolerances as those bent in the shop. There is no expanded tolerance for the field.
Concrete cover is the distance between the outer surface of the bar and the surface of the concrete. It protects the steel against corrosion and ensures stress transfer.
Table 3: Minimum Covers (cast-in-place concrete)
Element
Minimum Cover (mm)
Slabs and walls (bars ≤ 20M)
20
Slabs and walls (bars > 20M)
30
Beams and columns
40
Footings on soil
75
Concrete exposed to weather or freezing
50
Concrete exposed to aggressive agents (chlorides)
60-75 (depending on exposure)
> Note: These values are minimums. Engineering drawings may require greater covers. Always check the drawings before placing.
4.2 Supports and Cover Spacers
Plastic spacers: the most common, available in various heights (20, 30, 40, 50, 75 mm).
Mortar spacers: used for large covers (footings).
Metal supports (chairs): for slabs, with plastic tips at the ends.
Side spacers: to maintain the spacing between bars and the formwork.
Support Density:
Slabs: 4 supports per m² (minimum), arranged in a staggered pattern.
Walls: supports every 1.2 m horizontally and vertically.
Beams: supports every 1.0 m under the bottom bars.
4.3 Bar Spacing
The clear spacing between parallel bars must be at minimum:
1.4 × the nominal diameter of the largest bar
40 mm (absolute minimum)
1.33 × the maximum aggregate size (to allow concrete to pass through)
Practical Formula: Clear spacing ≥ max (1.4 db, 40 mm, 1.33 × max aggregate)
4.4 Lap Splices (CSA A23.3, Clause 12)
Lap splices are zones where two bars overlap to ensure structural continuity.
Types of lap splices:
Contact lap splice: bars touch each other, tied with wire.
Non-contact lap splice: bars are spaced apart (rare, requires justification).
Lap splice length (Lr): depends on steel grade, bar diameter, spacing, cover, and position (top or bottom bar).
Increase Factors:
Top bars (more than 300 mm of concrete below the bar): × 1.3
> Caution: These values are indicative. Engineering drawings always take precedence. Never reduce a lap splice length without written approval.
4.5 Ties (Rebar Ties)
Tie wire: annealed steel wire, gauge 16 (1.6 mm) or 18 (1.2 mm).
Types of knots:
Simple tie: for horizontal bars.
Figure-eight tie: for vertical bars (columns).
Wrap and twist tie: for seismic zones.
Tie spacing:
Horizontal bars: every 1.0 to 1.5 m.
Vertical bars: every 0.5 to 1.0 m.
Lap splice zones: additional ties (at least 3 per lap splice).
Stirrups: tied at each corner.
Practical Rule: At least 50% of intersections must be tied in slabs; 100% in walls and columns.
4.6 Bar Positioning in Elements
Slabs
Bottom bars placed first (main direction according to drawings).
Top bars supported by chairs or bolsters.
Chair height: top cover + bar diameter.
Top bars must be held in position during pouring (risk of floating).
Beams
Bottom bars in the span direction (tension).
Top bars at supports (negative moment).
Stirrups perpendicular to the beam axis, spaced according to drawings.
Stirrups must be closed (135° overlap) in seismic zones.
Columns
Vertical bars (longitudinal) held by stirrups or ties.
Stirrup spacing: tighter in lap splice zones (max 8 db) and in nodal zones (max 12 db).
Lap splices must be staggered: no more than 50% of bars spliced at the same section.
Walls
Vertical and horizontal bars forming a grid.
Vertical bars placed first (aligned with reference marks).
Horizontal bars placed next, on the outside of the vertical bars.
Ties at every intersection (or staggered according to drawings).
4.7 Placement Tolerances (CSA A23.1, Clause 7)
CSA A23.1 (Concrete: Constituent Materials and Execution of Work) defines placement tolerances:
Table 5: Reinforcement Placement Tolerances
Parameter
Tolerance
Concrete cover
+10 mm / -10 mm (or -0 if cover is critical)
Bar spacing
± 15 mm
Vertical position of bars (slab)
± 10 mm
Horizontal position of bars
± 25 mm
Lap splice length
+50 mm / -0 mm (never less than specified length)
Bend angle
± 2° to ± 3° depending on angle
> Exam Trap: The tolerance on lap splice length is unilateral: you may exceed the length, but never reduce it. A lap splice that is too short is a major non-conformity that may require remedial work.
4.8 High-Bond Bars and Prestressing Bars
High-bond (deformed) bars have ribs that improve anchorage in concrete. Never confuse them with smooth bars (used only for stirrups or secondary reinforcement).
Prestressing bars (strands, wires) are placed by specialized crews — the ironworker-reinforcing must not cut or bend them.
5. Practical Calculations for the Ironworker
5.1 Calculating the Number of Bars
Formula:
Number of bars = (Length of element - 2 × cover) / Spacing + 1
Example: Slab 6.0 m long, 15M bars spaced at 300 mm, cover 30 mm.
Developed length = Straight segment + 4 db (tail length) + π × (4 db + db) / 2
90° hook:
Developed length = Straight segment + 12 db (tail length) + π × (6 db + db) / 4
> Reminder: The tail length is measured from the end of the bar to the start of the bend, on the outside of the bend.
5.3 Calculating Total Weight
Total weight = Σ (number of bars × unit length × linear mass)
Example: 21 bars 15M, 6.0 m each.
Linear mass 15M = 1.570 kg/m
Total weight = 21 × 6.0 × 1.570 = 197.8 kg
5.4 Steel Percentage (Reinforcement Density)
Density = (Weight of steel / Volume of concrete) × 100
Slab: 80 to 120 kg/m³
Beam: 150 to 250 kg/m³
Column: 200 to 350 kg/m³
> Usefulness: These values are used to estimate steel requirements when bidding. They are not required on the exam, but help verify the consistency of drawings.
180.Concrete cover: verify with a gauge or cover meter.
181.Lap splices: measure the effective length (never less than specified).
182.Bends: angles and diameters conforming.
183.Ties: number and type conforming, no tie wire left in the concrete (corrosion risk).
184.Cleanliness: no dirt, oil, ice, or loose rust on the bars.
185.Stability: the reinforcement must not move under the weight of workers or concrete.
6.2 Common Non-Conformities
Defect
Probable Cause
Correction
Insufficient cover
Missing or poorly positioned spacers
Add spacers before pouring
Sagging bars (top slab)
Insufficient chairs
Reinforce supports
Lap splice too short
Cutting or placement error
Add a splice bar
Rusted bars with pitting
Inadequate storage
Clean or replace
Improperly closed stirrups
Incorrect bending
Re-bend (if possible) or replace
6.3 Documentation
Cutting and bending log: record lot numbers, quantities, dimensions.
Inspection report: signed by the ironworker and the inspector before pouring.
Material conformity certificate: provided by the steel mill (mill certificate).
7. Rebar-Specific Safety
Personal protective equipment: leather gloves (cuts), safety glasses (cutting sparks), steel-toe boots, hard hat.
Impalement hazard: bar ends must be protected with caps or bent down within 1.5 m of the ground.
Lifting: never lift a bundle of bars with an unprotected sling — sharp edges cut the fibres.
Working at heights: use harnesses; never walk on unsupported bars.
Shear: keep hands more than 150 mm from the blades; use a push stick for short bars.
Pitfalls to Avoid
201.Confusing steel grades: 400W vs. 500W. Check the raised marks. A 500W bar used in place of a 400W bar is acceptable (stronger), but the reverse is unacceptable.
202.Forgetting the top bar increase factor: a lap splice calculated for a bottom bar must be multiplied by 1.3 if the bar is in the top position (more than 300 mm of concrete below).
203.Hot bending: strictly prohibited. Hot bending weakens the steel and voids its certification.
204.Straightening a bent bar: even if the bar looks intact, its ductility is compromised. The bar must be rejected.
205.Using larger diameter bars without checking the drawings: a larger diameter may seem safer, but it changes the spacing, cover, and can create zones of poorly covered concrete.
206.Neglecting ties in lap splice zones: lap splices must have at least 3 ties distributed along the length.
207.Confusing cover and bar spacing: cover is measured from the outer surface of the bar to the formwork, not from the axis.
208.Forgetting protective caps: exposed bar ends are a deadly hazard on site.
209.Cutting bars with a grinder without eye protection: sparks and flying particles cause serious eye injuries.
210.Ignoring placement tolerances: a ± 25 mm tolerance on horizontal position does not mean you can shift a bar 50 mm "to make it easier."
Summary
Reinforcing bars are identified according to CSA G30.18: size (10M to 55M), grade (300, 400W, 500W), and weldability (W).
Cutting is done cold (shear or grinder); oxy-fuel cutting is prohibited for reinforcement.
Minimum bend diameters are 6 db (bars ≤ 20M), 8 db (25M-30M), 10 db (35M-55M), and 4 db for stirrups.
Bending tolerances: ± 2° (angles ≤ 90°), ± 3° (angles > 90°), position ± 25 mm.
Minimum cover ranges from 20 mm (interior slabs) to 75 mm (footings on soil).
Lap splices must meet the lengths on the drawings; the tolerance is +50 mm / -0 mm.
Ties: annealed wire gauge 16 or 18, spacing according to element type, minimum 3 ties per lap splice.
Placement tolerances (CSA A23.1): cover ± 10 mm, spacing ± 15 mm, vertical position ± 10 mm, horizontal ± 25 mm.
Before pouring: verify drawings, covers, lap splices, bends, ties, cleanliness, and stability.
Safety: gloves, glasses, caps on bar ends, sling protection, harnesses at heights.
Essential Formulas to Remember:
Number of bars = (Length - 2 × cover) / Spacing + 1
Developed length = Σ straight segments + Σ bent lengths
90° bent length = π × D / 4 (D = diameter at axis)
Weight = number × length × linear mass
Self-Assessment Questions
230.What is the standard cutting tolerance for a straight 6 m bar?
231.What is the minimum inside bend diameter for a 25M bar?
232.A lap splice of 800 mm is specified for 20M bars in the bottom position. What length must be provided if the bars are in the top position?
233.How many 15M bars are needed for a 4.5 m wide slab with 200 mm spacing and 30 mm cover?
234.What is the total mass of 35 bars 25M, each 7.5 m long?
235.True or false: a bar bent by mistake can be straightened if it is not cracked.
236.What is the minimum cover for an interior beam?
237.What is the tolerance on the vertical position of bars in a slab?
CSA A23.1 — Concrete: Constituent Materials and Execution of Work (placement tolerances, covers, quality control).
CSA A23.3 — Design and Construction of Concrete Structures (bend diameters, lap splice lengths, anchorages).
CSA S16 — Design of Steel Structures (for composite steel-concrete connections, if applicable).
> Note for the exam: The Red Seal evaluates practical competence and knowledge of standards. Questions often focus on real site situations: identifying a defect, choosing the right procedure, calculating a quantity. Practice solving problems with the tables above, without a calculator (the numbers are simplified for mental math).
