GRP vs Steel in Harsh Environments: Performance and Cost Over Time
Introduction
Steel has long been the default choice for structural and safety-critical applications. Its high strength and familiarity make it a trusted material for many construction teams. However, in harsh environments — coastal zones, chemical plants, wastewater facilities, and industrial sites — steel’s performance is challenged by corrosion, high maintenance demands, and shorter service life.
Glass Reinforced Plastic (GRP), manufactured to BS EN 13706 for pultruded profiles and BS EN 4592 for industrial flooring, offers a corrosion-proof, low-maintenance alternative. When evaluated over the full life cycle, GRP often outperforms steel in both cost efficiency and operational reliability.
This article examines how the two materials compare in real-world conditions, using technical data and case studies to illustrate long-term outcomes.
Corrosion Resistance and Material Longevity
In environments with high moisture, salt, or chemical exposure, steel requires protective coatings or galvanising to prevent rust. Even with these measures, coatings can degrade, leading to costly maintenance cycles.
GRP is inherently corrosion-resistant. Its composite structure is unaffected by saltwater, most industrial chemicals, and fluctuating weather conditions. This property is particularly valuable in:
● Coastal infrastructure (piers, sea defences, harbours)
● Water treatment and pumping stations
● Chemical processing facilities
● Offshore and marine applications
The Copenhagen Kastrup Airport blast wall is a clear example — GRP structural profiles were chosen over steel to withstand coastal salt spray and eliminate ongoing coating requirements, ensuring decades of service without corrosion-related intervention.
Weight and Installation Efficiency
Steel’s density means heavier components, greater lifting requirements, and more complex installation logistics. In remote or elevated sites, transporting and manoeuvring steel adds to both cost and safety risks.
GRP is up to 75% lighter than steel, enabling smaller installation teams, reduced plant hire, and faster assembly. This was demonstrated in the refurbishment of Poole’s Wharf pedestrian bridge, where GRP decking panels were carried and positioned by hand, avoiding lane closures and crane hire.
Maintenance and Lifecycle Costs
While steel’s initial purchase price may be lower in some cases, lifecycle costs tell a different story.
● Steel: Requires regular inspections, coating repairs, and occasional component replacement due to corrosion or fatigue.
● GRP: Requires minimal maintenance, typically limited to cleaning and visual inspections, with no corrosion treatment needed.
Over a 50-year design life, GRP’s reduced maintenance can lead to significant cost savings, particularly in operational environments where downtime is costly.
Safety Considerations
GRP’s non-conductive properties make it suitable for electrical environments where steel would require additional insulation or earthing. Its anti-slip surface options can also meet BS 7976 standards, improving safety in wet or oily conditions without extra surface treatments.
Standards Compliance
Both materials can meet structural performance requirements, but GRP’s compliance includes:
● BS EN 13706 for structural pultruded profiles
● BS EN 4592 for industrial flooring
● BS 476 Part 7 Class 2 for fire performance in relevant environments
With these standards met, GRP can be specified in the same performance category as steel while avoiding many of its maintenance liabilities.
Conclusion
In harsh environments, steel’s need for corrosion protection, its higher weight, and its maintenance demands make it less competitive over the long term. GRP offers comparable structural capability with inherent corrosion resistance, lower installation costs, and minimal upkeep, delivering tangible advantages in both performance and cost efficiency over time.
For contractors, factoring in lifecycle costs and operational risks can reveal GRP as a more sustainable and cost-effective choice in demanding settings.
