AU
NZ
UK
Video
FRP and Fire Performance in Infrastructure Projects
This Tech Talk Tuesday session explores how FRP behaves under heat and fire, with a focus on the materials Treadwell uses in structural profiles, gratings, and access systems.
FRP is a composite of:
- Glass fibers
Typically, E-glass was initially developed for electrical insulation. It offers high strength and retains stiffness up to relatively high temperatures, with softening beginning around 800 degrees Celsius. - Thermoset resins
Usually, polyester or vinyl ester is used for industrial FRP. These are cross-linked resins that do not melt like thermoplastics. At high heat, they char and eventually decompose rather than flow. - Additives
Fire retardants, UV stabilisers, pigments and other modifiers that tune performance for different environments, including water and wastewater plants, boardwalks, industrial platforms, and more.
Because the glass has a much higher softening temperature than the resin, the limiting factor in a fire is usually the resin matrix and its thermal decomposition over time.
The webinar explains:
- The basic material science behind FRP in fire
- Typical decomposition temperature ranges for polyester and vinyl ester systems.
- What actually happens in a fire event, including charring and loss of matrix
- How lab fire tests, such as AS 1530.3, ISO 9239 and ASTM E8.4, are used
- What inspections and decisions are needed after a fire or hazard reduction burn.
All of this is presented as general guidance, not project-specific fire engineering, and includes a strong recommendation to engage a fire engineer and refer to applicable codes, such as the NCC/BCA, for Australian projects.
Key Benefits
Predictable behaviour under heat
- No melting of the thermoset matrix
Polyester and vinyl ester resins used in structural FRP are thermoset systems. They cross-link during curing and do not melt when reheated. Instead, they char and eventually decompose, which avoids the dripping and flowing seen with many thermoplastics. - E-glass retains strength to relatively high temperatures.
E-glass fibres have softening points in the range of roughly 800 degrees Celsius and melting above about 700 degrees Celsius, so the fibre phase remains intact up to temperatures where the resin has already started to degrade.
This predictable sequence of char, matrix damage, and eventual loss of bond helps designers and asset owners determine when FRP is expected to retain capacity and when it must be treated as damaged.
Tunable fire performance through additives
- Fire-retardant resins
Fire retardant additives can be incorporated into the resin to reduce flame spread and improve indices in tests such as AS 1530.3 and ASTM E84, where FRP products regularly achieve classifications comparable to many building materials when correctly formulated. - Enhanced surface char layer
Some fire retardant packages promote a protective char on the surface. This can slightly reduce decomposition onset temperature, but the thicker char layer tends to insulate the underlying FRP and limit heat penetration into the structural core.
This tunability allows Treadwell to specify resin systems that meet project-specific requirements for critical radiant flux, smoke indices, or surface-burning characteristics.
Case proven durability in harsh environments
The session connects fire behaviour back to Treadwell’s core markets, where FRP is already chosen for corrosion resistance and lifespan:
- Water and wastewater treatment plants
Vinyl ester systems with proven 50-plus-year design life in highly aggressive environments are used, often in structures where occasional fire exposure is a secondary consideration compared with corrosion and chemical attack. - Public infrastructure and boardwalks
National park authorities and asset owners are increasingly using FRP decks and walkways in bushland settings for their corrosion resistance and reduced maintenance requirements. The webinar references hazard reduction burns and bushfire feedback to illustrate how FRP structures have performed in practice. Other FRP suppliers in bridge and boardwalk applications have reported similar case studies.
Clear guidance on inspection and post-fire decisions
The session emphasises visual cues and engineering checks that help determine whether FRP can remain in service after a fire:
- Charred but intact surfaces may be acceptable where glass is not exposed, and deflections stay within limits
- Exposed glass fibres and significant matrix loss are treated as indicators that repair or replacement should be evaluated.
- Temperature histories and exposure durations matter: strength is generally recoverable after cooling if maximum temperatures remain below a specific range, whereas long exposures at elevated temperatures cause permanent damage.
This gives owners and engineers a practical framework for deciding whether to leave, repair, or replace FRP components.
Applications
Boardwalks and walking tracks in bushfire-prone areas
FRP is widely used for boardwalks, platforms, and access structures in coastal and bush settings because it is:
- Corrosion-resistant in marine and wet environments
- Lightweight for remote installation
- Non-conductive and low maintenance.
In the webinar, Treadwell references:
- A hazard reduction burn where FRP walk structure panels were exposed to a controlled grass fire. After the burn, the panels remained standing, with superficial charring but no exposed glass, so no replacement was required.
- Feedback from park authorities after major bushfires, where some FRP elements were damaged beyond repair, but adjacent concrete bridges and steel components were also heavily damaged or warped, indicating that the severity of the fire, not just material choice, drove replacement.
These examples align with independent research showing that FRP performance in real fires depends strongly on incident heat flux, fire duration, and detailing, rather than on a single material property.
Industrial platforms and access systems
In plant environments, FRP gratings and profiles are often used for:
- Chemical and wastewater treatment platforms
- Cooling tower access and surrounds
- Offshore and coastal structures
Here, the primary drivers are corrosion resistance and life cycle cost. Fire is treated as a design scenario that must be understood, rather than something FRP is expected to resist as a primary fire-rated structural element. The session reinforces that:
- FRP is not typically used where an FRL rating is required for primary building frames or fire-rated separation elements under the NCC
- It can still be a practical choice for secondary structures, walkways, and platforms, provided that fire scenarios are understood and that appropriate standards and test data are included in the design brief.
Coastal and marine infrastructure
For waterfront and marine assets like jetties, pump stations, and intake structures, FRP combines:
- High corrosion resistance
- Electrical insulation
- Reduced weight compared with steel or concrete
The session notes that in such environments, fire exposure is usually limited to short-duration events, and FRP’s charring and self-extinguishing behaviour (under certain fire test conditions) can be an advantage where ignition sources are localised. This is consistent with results from surface burning tests such as ASTM E84, where well-formulated FRP can achieve low flame spread indices.
Design and engineering support for elevated temperature service
Apart from actual fire events, some projects expose FRP to sustained elevated temperatures, for example:
- Structures adjacent to ovens, kilns, or dryers
- Areas with hot process streams or exhausts
The session links back to guidance from the American Composites Manufacturers Association and other design manuals that give reduction factors for mechanical properties as internal material temperature rises. Engineers can use those factors to:
- Derate section capacity at elevated service temperatures.
- Check deflections and stability under steady hot conditions, not just ambient conditions.
- Decide whether FRP is suitable in a particular high-temperature location.
Key Moments
- 00:19 📅 The session was delayed by two weeks, but it resumed with discussions on FRP behavior in fires.
- 00:48 🔍 The topic focuses on general advice regarding FRP and its reactions in real-world fire and heat situations.
- 02:12 📦 FRP stands for fiber-reinforced polymer, primarily made of glass fibers and thermoset resin.
- 04:21 🔥 Thermoset resins in FRP do not melt; they char when exposed to high temperatures.
- 06:13 ⚠️ FRP's fire performance is influenced by factors like temperature increase rate and duration of exposure.
- 07:08 📊 Decomposition temperatures differ for polyester (164–380°C) and vinyl ester resins (450–620°C) regarding weight loss.
- 09:00 🔧 Mechanical properties of FRP decrease as temperature increases, especially in sustained high heat environments.
- 11:35 🧯 Certain fire retardants reduce decomposition temperatures but may increase the rate of surface charring.
- 15:15 🔥 Real-world tests show FRP can withstand fire exposure without structural failure if properly designed.
- 18:09 ⚖️ FRP is not intended for primary structural use in fire zones; consultation with a fire engineer is advised.
- 19:31 🌿 Post-bush fire product performance can vary, with some products remaining intact after moderate fire exposure.
Why Treadwell?
The webinar closes by reinforcing how Treadwell supports designers, asset owners, and contractors who need to understand FRP in fire:
- Material transparency
Treadwell uses recognised FRP formulations with clearly defined glass types, resin families, and fire-retardant packages, backed by third-party fire testing to standards such as AS 1530.3, ISO 9239, and ASTM E84, where relevant. - Design guidance and standards literacy
The team actively references international FRP design manuals and stays aligned with Australian code requirements, helping clients bridge the gap between composites literature and local building or infrastructure standards. - Real-world fire performance experience
Treadwell has direct feedback from national park authorities, water utilities, and industrial clients on how FRP assets have performed in hazard-reduction burns, bushfires, and localised fire incidents, which informs practical inspection and replacement guidance. - Project-specific support
Rather than giving one-size-fits-all assurances, Treadwell invites project-specific discussions with engineers and fire consultants. The focus is on selecting the right FRP resin system, detailing, and inspection regime for the actual fire scenarios, whether that is bushfire exposure, process heat, or general building code compliance.
For designers and asset owners who want to leverage the corrosion resistance and life-cycle benefits of FRP while remaining clear-eyed about fire behaviour, this Tech Talk Tuesday session provides a grounded, technically informed overview and a clear path to more detailed, project-level support.
