Structural and base materials · Concrete & Cement
Non-Metallic Reinforcement Bar
Explains a reinforcement product whose defining property is the absence of corrosion, and the handling, fabrication and detailing consequences that follow from it.
Educational reference entry. Suitability depends on the complete assembly, substrate, exposure, installation method, manufacturer documentation, local requirements and qualified professional review.
Overview
What non-metallic bar is
A non-metallic reinforcement bar is made from continuous fibres — commonly glass or basalt, sometimes carbon or aramid — drawn through a resin and cured into a solid bar with a surface texture or wrapping that gives it grip in concrete. It is supplied in lengths and in prefabricated shapes, and it is fixed and tied into a cage in much the same way that steel bar is.
The property that governs everything else about it is that it does not corrode. In a steel-reinforced element, the concrete cover is doing two jobs at once: holding the bar in place and keeping an alkaline, uncarbonated environment around it so the steel stays passive. Remove corrosion from the picture and the second job disappears, which changes what the designer is protecting against and what the consequences of a crack or a thin patch of cover actually are.
Three other characteristics follow from the material rather than from the comparison. Bends cannot be made on site: the resin is cured, so every bend, hook and link is a factory item ordered to a schedule, and a bar cannot be persuaded into position with a bender the way steel can. The bar is light enough to be carried and placed by hand, which changes the site operation for long lengths. And it is electrically and magnetically inert, which is why it is met in rooms containing scanning or sensing equipment, around induction and transmission installations, and wherever a steel cage would interfere with what the building is for.
Behaviour in fire and under sustained load is different from steel's, and so is the way the bar responds when it is loaded — it does not yield in the way a steel bar does. Those are design characteristics rather than product features, and how they are handled belongs entirely to the engineer responsible for the element.
Terminology
Common names and aliases
These names describe the same thing. The library keeps one entry per material so that an acronym, a trade name or a regional spelling never becomes a second, thinner page.
- FRP rebar
- Fibre-reinforced polymer bar
- GFRP bar
- Glass fibre reinforcement bar
- Basalt fibre rebar
- Composite reinforcement
Applications
Common applications
Where this material is typically encountered. A typical application is not a statement that it suits your project.
- Elements in aggressive or chloride-rich environments where the corrosion of embedded steel is the governing concern.
- Concrete around scanning, imaging and sensitive electronic equipment where a conductive cage is a problem.
- Slabs and walls near induction, transmission or high-current installations.
- Ground-retaining and soil-nailed work where reinforcement is intended to be cut through later by tunnelling or piling.
- Marine, coastal and de-icing-salt-exposed structures where cover has historically been the weak point.
- Thin sections and repairs where the depth available makes a corrosion-protected steel arrangement difficult.
Consideration
Where it is commonly considered
- Where the designer has identified corrosion of reinforcement as the dominant durability risk for the element.
- Where a non-conductive or non-magnetic element is required by the use of the building.
- Where reinforcement will need to be cut through by later works and a steel cage would obstruct that.
- Where the exposure is severe enough that the team is discussing alternatives to conventional steel arrangements.
- Where handling weight on site is a genuine constraint for long lengths of reinforcement.
- Where an engineer has already worked with the material and is proposing it for a specific reason.
Professional review
Where additional professional review is especially important
These are the situations where the answer depends on the specific building, and where a qualified professional should be involved before anything is decided.
- Where the element is structural and the designer has not specifically designed for this material — it is not a substitution for steel bar.
- Where fire behaviour of the element matters and the material's response has not been considered by the designer.
- Where bends, links or laps will be needed that have not been ordered in advance as factory items.
- Where the site team expects to cut, bend or adapt reinforcement as the work proceeds.
- Where the designer's detailing assumes the ductile behaviour of steel under load.
- Where nobody on the team has handled the material before and the fabrication lead time has not been allowed for.
Properties
Key properties to discuss
Qualitative topics worth raising. Measured values, classes and grades come from the manufacturer's technical documentation for the specific product, not from a reference page.
- Installation dependency
- It is placed and tied like steel but cannot be altered on site. Schedules, bends and lengths are fixed at the point of ordering, so a setting-out error is a re-order rather than an adjustment with a bender.
- Substrate dependency
- It is embedded in concrete and depends on the bar's surface texture for grip. How much cover is provided is still a design decision, but the reason for providing it is no longer corrosion protection of the bar.
- Weathering and exposure
- The bar does not corrode, which is the reason it appears in coastal, de-iced and chloride-rich locations. Everything else about the durability of the element — the concrete, the cover, the detailing, the drainage — still applies.
- Fire-related questions
- A resin-matrix bar behaves differently from steel when heated, and the implications for an element belong to the engineer designing it. This reference does not describe fire behaviour or state any performance.
- Documentation
- Because the material is less familiar than steel, the manufacturer's technical information and the designer's justification carry more weight, and the bar schedule is the record of what could not be changed on site.
- Repairability
- Later interventions differ: the bar can be cut through by tools that would struggle with steel, which is sometimes the point, and sometimes a risk to be flagged to whoever works on the structure next.
- Maintenance
- There is no reinforcement corrosion to monitor, so the inspection subjects for the element shift towards the concrete itself, the joints and the water management around it.
Exposure
Exposure and environmental conditions
- Is the element in a chloride-rich, coastal or de-iced environment, and is that the reason for the choice?
- Does the use of the building involve equipment sensitive to a conductive or magnetic cage?
- Will the bar be exposed to sunlight or to weather while it is stored on site before the pour?
- Is the element in a position where fire behaviour is a design consideration?
- Does the ground chemistry at this location form part of the designer's reasoning?
Assembly
Substrate and system dependencies
What this material sits on, is fixed to or depends on. This is usually where performance is won or lost.
- The reinforcement schedule is fixed before delivery because nothing can be bent or formed on site.
- Spacers and chairs are still needed to hold position during the pour, and the type used has to suit the bar.
- Tying and cage stability are handled differently because the bar is lighter and behaves differently under handling.
- Laps, anchorages and connections are detailed by the designer specifically for this material.
- Cast-in items, penetrations and starter arrangements are coordinated before fabrication rather than adapted afterwards.
- Concrete placing and compaction around a lighter cage need care so the cage is not displaced or floated.
Appearance
Appearance and finish considerations
- The bar is cast in and is not visible in the finished element, so appearance is not a selection subject.
- Where bar ends project from a construction joint they look quite different from steel starter bars.
- Surface staining from corroding reinforcement, a familiar sign on older concrete, does not arise from this material.
- Cut ends and handling damage are visible during construction and are reported to the designer rather than made good on site.
Durability
Durability questions
Questions to raise rather than a service life to expect. No material has a universal lifespan — it depends on the assembly, the exposure and the upkeep.
- Why was this material chosen for this element, and by whom?
- What is the cover doing in this design now that corrosion protection is not its purpose?
- How does the designer expect the element to behave in fire, and is that documented?
- Has the material been considered for sustained load in this position?
- What monitoring, if any, does the designer expect for this element in service?
Upkeep
Maintenance and repair considerations
- What record exists so future works know the reinforcement is not steel?
- How would anyone drilling or cutting into this element find out what is in it?
- Does a repair to this concrete need different materials or methods because of the reinforcement?
- Are there inspection subjects for this element that differ from a steel-reinforced one?
Installation
Installation dependencies
What the installation depends on — not how to do it. Method belongs to the manufacturer's instructions and the trades carrying out the work.
- Fabrication lead time is part of the programme because every shape is a factory item.
- Storage on site protects bars from damage and from conditions the manufacturer's information identifies.
- Handling is easier by weight but the bar behaves differently, so the fixing crew may need briefing.
- Cutting is possible with the right equipment, but bending is not, and a shortfall is a re-order.
- Cage support and stability during the pour need attention because the cage is lighter than a steel one.
- The designer is consulted about any deviation, because substitution decisions are not site decisions.
Documentation
Documentation to request
Ask for these in writing, for the specific product being proposed, and keep them with the project record.
- The manufacturer's technical information for the specific bar supplied.
- The designer's reinforcement drawings and schedules prepared for this material.
- The designer's written reasoning for using a non-metallic bar in this element.
- Handling and storage information from the supplier.
- A record for the building file noting that the reinforcement in this element is not steel.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- Why is this material being used here rather than steel bar?
- Has this element been designed for this material from the start, or adapted from a steel design?
- What is the cover in this element being provided for?
- How are laps, bends and anchorages being handled, and when do they need ordering?
- What happens if the setting out changes after the bars have been fabricated?
- How has fire been considered for this element?
- What do we need to record so that future works know what is inside this concrete?
- Are there parts of this structure where steel is still being used, and why the difference?
Blind spots
Commonly overlooked points
- It is not a drop-in substitute for steel bar; an element is designed for it or it is not used.
- Nothing can be bent on site, so a fabrication error stops the pour rather than delaying it by an hour.
- Cover is still specified, but it is no longer there to keep the reinforcement passive.
- Future works — drilling, fixing, cutting — will find something other than steel, and that is worth recording.
- The absence of rust staining removes a familiar early warning sign that owners are used to looking for.
- Lead times for factory-formed shapes are a programme item that steel bar rarely imposes.
What this page does not do
- This page does not state any structural, fire or durability performance for this material; all of those are engineering determinations for a qualified professional.
- Non-metallic reinforcement is never a site substitution for steel reinforcement shown on a drawing.
- Where local requirements govern reinforcement in a given element, they are verified with the designer and the relevant authority rather than assumed.
- Build Design Hub does not supply, test, approve or endorse reinforcement products or any supplier of them.
Related entries
Common comparisons
Entries met at the same decision but which behave differently, so the comparison is about the difference rather than a swap.
Related entries
Often used alongside
Entries commonly encountered together with this one. Co-occurrence only — never a claim that any combination is compatible or suitable.
Inspiration
Related Ideas Library pages
Design directions where this material commonly appears.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this material comes up.
Go deeper
Related Build Design Hub guides
Planning guidance and neutral comparisons behind the decisions on this page.
Concrete & Cement Materials
Reference entries for cement-based materials — ready-mixed and precast concrete, screeds, levelling compounds, renders of the cementitious family and the admixtures that modify them.
Browse all concrete & cement entries →