Two products share the name: a fiberglass bar sold under a green brand, and steel under a green epoxy film. How to tell which one you have, then what each is specified by.
← Back to the calculatorIf the bar is green through the whole cut section, it is a fiberglass bar. If the green is only a film and there is steel under it, the green is just the colour of the coating — the same coating as any other coated bar, in green.
The word splits because one manufacturer put it in a trademark: Greenbar2X is a fiberglass bar, and the green in that name is branding. The green that contractors mean on site is the fusion-bonded epoxy film, and that one is a colour, not a product name. Both come back for the same search, and none of the pages that rank for it say so.
The rest of this page is the test that tells them apart in ten seconds, and what each one is actually specified by — because the two are not interchangeable in a bar list, a lap, or a submittal.
The top ten for this query is not a list of competitors. It is two shelves standing next to each other. Three results are the same fiberglass product sold under one brand (a home centre listing, a second home centre category page, and the manufacturer's own page). Six are coating: two aerosol touch-up cans, a plant-applied fusion-bonded epoxy maker, a paint maker's technical data sheet, a supplier page, and a coatings catalogue. One is a video.
That is the whole confusion in one screenshot. The fiberglass pages talk about rust-free, lightweight, non-magnetic. The coating pages talk about touch-up, cut ends, and dry time. Neither set mentions the other, so a reader who searched one word gets two answers that never touch.
You do not need a datasheet to tell which one is in your hand.
None of those three tests needs a standard number. They are there so you buy the right thing before you get to the numbers.
The product standard is ASTM D7957, and it lists tensile properties for the straight bar — it does not carry a separate value for the bent portion. That matters because the bar is anisotropic: a bend is not the same material as the run.
What the numbers look like in the published literature: tensile strength 70 to 230 ksi, modulus 5,100 to 7,400 ksi, strain at rupture 1.2 to 3.1%. That is a three-fold spread in strength and a 1.6-fold spread in stiffness, so a single “fiberglass rebar” number does not exist — the range is the number. There is no yield point: the bar is linear to rupture, which is why the design check is deflection and strain, not stress.
The bent portion loses 40 to 50% of its straight-bar strength, and the bar cannot be bent after it is formed. Those two sentences are the ones a submittal review actually turns on, and they are on the fiberglass page with the source for each.
The green film is fusion-bonded epoxy, and the number that governs it is thickness: 7 to 12 mil after curing, with at least 90% of all recorded readings inside that band for acceptance. The colour is not a grade. A green bar and a grey bar can be the same product from two plants.
The thickness is also where the two green products finally meet: the film at the plant is 7 to 12 mil, and the aerosol can in the same search results puts down 4 to 5 mil. Those are not the same coating applied two ways. That comparison, with the arithmetic, is on green rebar epoxy coating.
Three things are called green rebar and only two are products.
If a page uses the word without saying which of the three it means, it is not answering the query yet.
Not always. Fiberglass rebar is sold under at least one brand with green in the name, so a search for green rebar returns it, but the same phrase also means a steel bar with a green fusion-bonded epoxy coating. Cut one: fiberglass is the same colour through the section, a coated bar shows a steel core under a film, and a magnet sticks to the coated bar and not to the fiberglass one.
Because the fusion-bonded epoxy used on reinforcement is green. The colour is the coating, not a grade and not a marker of thickness: the specification that governs the bar is the film thickness, 7 to 12 mil after curing, and the acceptance rule is that at least 90% of recorded readings fall inside that band.
Three checks, no tools. The cut end: solid colour through the section means fiberglass, a bright steel disc under a film means coated steel. A magnet: it holds on steel and falls off fiberglass. Weight: a fiberglass bar lifts in one hand where a steel bar of the same size does not.
The fiberglass one can be, per square inch of bar, and it still is not a swap. Published tensile strengths run 70 to 230 ksi against 60 to 90 ksi for Grade 60 and 75, but the modulus is 5,100 to 7,400 ksi against 29,000 ksi for steel, so the same bar deflects far more, and there is no yield point to redistribute load. Whether it can replace steel is a design question about deflection and strain, not a strength comparison.