Types of Rebar in Canada: Black, Epoxy, Galvanized, Stainless and GFRP

There are five main types of rebar used in Canada: plain carbon steel (black) bar, epoxy-coated bar, galvanized bar, stainless steel bar and glass fibre reinforced polymer (GFRP) bar. Black bar made to CSA G30.18 does the bulk of the work in footings, walls, slabs and frames. The other four exist to deal with corrosion, mostly where road salt or seawater reaches the concrete.

This post is the overview. Each type gets a short explanation, the standard behind it, and a link to the more detailed post where we have one.

The types at a glance

Two related products often get lumped in with rebar. Welded wire mesh is a grid of cold-drawn wires welded at the crossings, used mostly in thin slabs. Smooth dowel bars are plain round bars used at pavement joints, where the bar has to slide rather than grip. Both are reinforcement, but they are bought and specified differently from deformed rebar.

Black bar: the standard carbon steel rebar

When people say "rebar" without qualification, they mean black bar. The name comes from the dark mill scale on the surface, not a coating. "Non epoxy coated rebar" and "uncoated rebar" mean the same thing.

In Canada, black bar is made to CSA G30.18, Carbon steel bars for concrete reinforcement. The standard covers two types of hot-rolled deformed bar, regular (R) and weldable (W), at two minimum yield strengths, 400 MPa and 500 MPa. That gives four grades:

• 400R and 500R: regular grades for general use. The R is used on orders and drawings but is not rolled onto the bar.
• 400W and 500W: weldable grades with tighter limits on chemistry and mechanical properties, which also gives better ductility. The W is rolled onto the bar.

Grade 400W is the default on most Canadian drawings. Our post on rebar grades in Canada explains when 500W shows up and what changes with it. Black bar comes in the eight metric sizes from 10M to 55M, listed with weights in our Canadian rebar size chart.

Black bar is protected from rust by the concrete itself. Fresh concrete is highly alkaline, which keeps the steel surface passive, and the cover between the bar and the surface keeps water and salts away. In most buildings, adequate cover and good concrete are all the corrosion protection the bar needs. That is why concrete cover requirements matter as much as the bar itself.

Coated steel bar: epoxy and galvanized

Coated bars keep a black-bar core and add a barrier on the surface. They are specified where chlorides are expected to get through the cover over the life of the structure.

Epoxy-coated rebar

Epoxy-coated bar has a fusion-bonded epoxy film, usually green when the bar is coated straight and then fabricated (ASTM A775), and often purple or grey when it is bent first and coated afterwards (ASTM A934). The coating isolates the steel from moisture and chlorides as long as it stays intact, so handling, coated tie wire and touch-up of cut ends and damaged spots all matter. The coating also reduces bond, which makes laps and development lengths longer.

Our post on when epoxy-coated rebar is required covers the specifications, the design changes and the handling rules.

Galvanized rebar

Galvanized bar is coated with zinc by hot dipping. Zinc protects the steel in two ways: as a barrier, and by corroding preferentially, so small scratches do not expose the steel in the way a damaged epoxy film does. There are two production routes:

• ASTM A767: batch hot-dip galvanizing. Bars are normally cut and bent first, to bend diameters set by the standard, then galvanized and given a chromate treatment.
• ASTM A1094: continuous galvanizing, where straight bar runs through a coating line. This coating is made to be bent after galvanizing.

For a direct comparison of the two coatings, see galvanized vs epoxy-coated rebar.

Solid corrosion-resistant bar: stainless and chromium steel

Instead of protecting carbon steel with a coating, these bars are made of a steel that resists corrosion through its whole section, so there is no film to scratch.

Stainless steel rebar (ASTM A955) is the top end for chloride resistance. The Ontario Ministry of Transportation began specifying it in severe exposure zones of bridge decks in the early 2000s, after concluding that epoxy-coated bar would not give the service life it wanted. It is a premium material, so designers often use it only in the most exposed elements, such as a deck or a barrier wall, with black bar elsewhere.

Low-carbon chromium steel bar (ASTM A1035) sits between carbon and stainless steel. It is known mainly for its high strength, with better corrosion resistance than black bar.

Galvanized vs stainless steel rebar

The two are often compared because both avoid the handling sensitivity of epoxy. In short:

• Protection. Stainless relies on the alloy itself. Galvanized relies on a zinc layer that is consumed slowly over time.
• Exposure. Stainless is chosen for severe chloride exposure and long design life. Galvanized suits moderate exposure, architectural and precast work.
• Fabrication. Stainless can be cut and bent like other bar without coating repairs. Batch-galvanized bar is bent before coating, and cut ends need touch-up.
• Mixing metals. Specifications usually limit direct contact between different bar types, so ask the designer before combining them in one element.

GFRP: the non-steel option

Glass fibre reinforced polymer bar is not steel at all. It is made of continuous glass fibres bound in a resin, so it cannot rust, does not conduct electricity and weighs a fraction of steel bar of the same size. In Canada the material is covered by CSA S807, and structures reinforced with it are designed to CSA S806 for buildings or CSA S6 for bridges. MTO started specifying GFRP in bridge decks in 2005.

GFRP has a higher tensile strength than steel but is much less stiff, does not yield before it breaks, and cannot be bent on site, so bends have to be made by the manufacturer. It is designed differently, not swapped one-for-one. Our GFRP vs steel rebar comparison covers the trade-offs, and fiberglass rebar and CSA S807 and S806 explains how it is specified.

Epoxy-coated rebar vs fiberglass rebar

These two are compared because both target the same corrosion problem:

• Durability. Epoxy protects steel only where the film is intact. GFRP has nothing to corrode.
• Design. Epoxy-coated bar is designed as steel with longer laps. GFRP is designed to its own standards, often with more or larger bars because of its lower stiffness.
• Site work. Epoxy-coated bar needs padded handling and touch-up. GFRP is light and easy to carry but needs every bend factory-made.
• Specifications. Many owners now name which one they accept, so the contract documents decide.

Choosing the type for your job

The type of rebar is a design decision, not something to swap on site. A practical way to read your project:

1. Check the drawings and specification. If they name a type, grade and standard, that is what the job needs. Most building drawings simply call for Grade 400W black bar.
2. Look at the exposure. Chloride exposure classes, parking structures, bridge work and marine work are where coated, stainless or GFRP bar appears.
3. Check the owner's rules. MTO, municipalities and parking garage owners often limit which corrosion-resistant bars they accept.
4. Get any substitution approved in writing. Changing the bar type changes laps, cover details, accessories and sometimes the whole reinforcement layout.

Getting the right bar supplied

We supply black bar from 10M to 55M, straight or cut, bent, tagged and bundled to your bar list, along with fabricated dowels and stirrups and GFRP rebar. We don't supply epoxy-coated, galvanized or stainless bar.

Send us your drawings or bar list for a free take-off and quote, or see our rebar products.