Structural consultants
Engineers who need tensile strength, stiffness and bond stated separately before they redesign a member.
Comparison page · GFRP and TMT
GFRP rebar vs TMT steel: cost and technical comparison
An educational comparison for engineers, procurement teams and project heads. It sets out what is different about the bar, what changes in the design, and which cost lines to compare. It does not offer one saving figure for every project.
Published by 7 Star IMPEX LLP · 18 October 2026 · Property figures are from 7 STAR’s published product literature and the test reports printed in it.
01
Who this comparison is for
Most GFRP questions start with “is it cheaper than TMT?” The honest answer depends on the element, so this page is written for the people who will check the numbers.
Procurement teams
Buyers comparing a per-kg steel rate with a per-metre GFRP rate and needing the lines that sit between them.
Project heads
Decision-makers weighing first cost against corrosion, maintenance and programme.
Contractors
Site teams who will carry, cut, tie and place the bar, and who carry the risk of scrap and theft.
02
The bar, property by property
Steel values are for Fe 500 grade, as 7 STAR’s literature presents them. The GFRP strength and modulus figures are the averages from the tensile test reports printed in the same literature (tests carried out for Armastek, 7 STAR’s technology partner).
| Property | TMT steel (Fe 500) | GFRP rebar | What it means |
|---|---|---|---|
| Tensile strength | 500 MPa minimum | About 1,050–1,240 MPa (test averages, 6–20 mm) | More tensile capacity per square millimetre. |
| Modulus of elasticity | About 200 GPa | About 45–53 GPa (test averages) | Roughly a quarter as stiff. Deflection and crack width often govern the design. |
| Elongation | 12% minimum, with a yield plateau | About 2–3% at failure, no yield | Linear-elastic to rupture. No ductile warning, so safety factors differ. |
| Weight, 8 mm bar | 0.395 kg/m | 0.079 kg/m | About one fifth of the weight at the same diameter. |
| Density | 7.8 t/m³ | 1.9 t/m³ | Freight and handling change most. |
| Supply length | 12 m bars | Coils up to 100 m in small diameters; 12 m bars above 12 mm | Fewer laps on long runs. |
| Corrosion | Rusts if cover or exposure fail | Does not rust | The main reason to specify GFRP in wet, saline and chemical exposure. |
| Electrical and magnetic | Conductive and magnetic | Non-conductive and non-magnetic | Useful near induction loops, sensitive equipment and electrical rooms. |
| Transverse shear | 120 MPa | 170 MPa | Literature figure. Shear design still follows the GFRP design guide. |
| Bond strength | 14 MPa | 12.5 MPa | Slightly lower. Development and lap lengths are calculated for GFRP. |
| Compression | 500 MPa | 450 MPa | Design guides such as ACI 440.1R do not rely on GFRP bars in compression. |
| Concrete cover | 35–45 mm | 20 mm (literature figure) | Cover follows the project code and fire rating, not the brochure. |
03
What changes in the design
A GFRP schedule is a new design, not a find-and-replace on bar marks. These are the points a consultant will check first.
Strength is not the limit, stiffness is
With twice the tensile strength and a quarter of the stiffness, many slabs are sized for deflection and crack width, not strength. Bar area may fall, stay the same or rise.
Design guide changes
GFRP members are designed to FRP guides such as ACI 440.1R. Road components follow the references IRC:137-2022 sets out. A steel code is not applied to a GFRP bar.
Bends are made in the factory
GFRP cannot be bent on site. Stirrups and shaped bars are ordered against a drawing, so the bending schedule has to be ready earlier.
Laps and development lengths
Bond differs from steel, so lap and anchorage lengths are recalculated. Long coils can remove many laps on slabs, drains and pavements.
Fire and temperature
GFRP softens at high temperature. 7 STAR’s FAQ notes concrete cover protects the bar and fire-tested slabs stay structurally safe. Fire-rated members need the consultant’s check.
Mixed reinforcement
Many projects use GFRP in slabs, pavements and drains while columns and primary frames stay in steel. 7 STAR’s FAQ describes exactly that split for seismic zones.
04
How to compare the cost properly
Per kilogram, GFRP looks more expensive. Per metre and per finished element, the picture changes. These are the lines a fair BOQ comparison includes. Leave any of them out and the answer is wrong in one direction or the other.
| Cost line | What changes with GFRP | What to check |
|---|---|---|
| Bar rate | Higher per kg, far lower weight per metre | Compare rate per metre and per element, never per kg alone. |
| Bar quantity | Set by the GFRP redesign | Use the consultant’s GFRP schedule, not a converted steel schedule. |
| Laps and overlap | Long coils remove many laps | Count the laps actually saved on the drawing. |
| Freight and lifting | About one fifth of the weight | Truck loads, crane time and manual handling on site. |
| Labour and placing | Lighter bars and ready mesh place faster | Crew size and days on your programme, not a brochure rate. |
| Scrap and reconciliation | Cut-to-length supply; offcuts have no scrap resale market | Your current steel wastage and reconciliation losses. |
| Corrosion protection | No coatings or corrosion-inhibiting admixtures for the bar | What the steel design specifies for exposure today. |
| Maintenance and life | No rust-driven repairs | Repair history of similar steel elements on your sites. |
| Price movement | Steel rates move with raw material and market prices | Agree a rate validity period for whichever material you buy. |
Why there is no headline percentage here
Savings depend on the element, the exposure, the steel price on the day and how many of the lines above apply. 7 STAR prepares project-wise BOQ comparisons on request. That is the number worth using.
05
Where TMT should stay
An honest comparison includes the cases where steel is still the right bar.
Keep steel for these
- Columns and members that work mainly in compression.
- Primary beams and columns in seismic frames, where steel’s ductility is relied on. 7 STAR’s FAQ uses GFRP for slabs and secondary elements in seismic zones.
- Members that must be bent on site.
- Road components outside the IRC:137-2022 permitted list.
- Fire-rated members, unless the consultant has checked GFRP for that rating.
GFRP suits
Slabs on grade, industrial and warehouse floors, pavements, drains, boundary walls, retaining walls, water tanks, STPs and precast items, especially in wet, saline or chemical exposure.
Read next
GFRP mesh for floors, roads and drainage, BIS and IRC standards, and precast and bent elements.
06
GFRP and TMT questions
Is GFRP rebar stronger than TMT steel?
In tension, yes. The tensile test averages printed in 7 STAR’s literature are about 1,050 to 1,240 MPa, against a 500 MPa minimum for Fe 500 steel. GFRP is also about a quarter as stiff and does not yield, so a stronger bar does not automatically mean a smaller one.
Is GFRP cheaper than TMT?
Per kilogram, no. Per metre and per finished element, it often is, once weight, laps, freight, labour, scrap and corrosion protection are counted. The answer is project-specific, so ask for a BOQ comparison on a real element.
Can I replace a 12 mm TMT bar with a 12 mm GFRP bar?
Not by substitution. The GFRP schedule has to be designed for its lower stiffness and different bond. Diameter and spacing may change in either direction.
Can GFRP be used in columns?
No. Columns and heavy compression members stay in steel. GFRP is used where reinforcement works in tension, such as slabs, pavements, walls and drains.
How long does GFRP last?
7 STAR’s literature gives a service life of 80 to 100 years or more, because the bar does not rust. Actual life also depends on concrete quality, cover and loading.
Can GFRP and TMT be used together?
Yes. A common pattern is GFRP in slabs, floors and drains, with steel kept in columns and primary frames. 7 STAR’s FAQ says the two can be tied together with normal binding wire on building work. Road works follow IRC:137-2022 tying rules.
07
Ask for a like-for-like BOQ
Send one real element, such as a slab, a drain section or a wall panel. The comparison lists every assumption. You can also call +91-7669275932 or write to contact@7stargfrp.com.
Application pages: Flooring · Roads & Drains · Standards · Precast & Bent. Or read the 7 STAR GFRP blog.