Test Results on FRP Recessed Covers' Fire Resistance

Fiber Reinforced Polymer FRP recessed covers are valued for their durability and lightweight design, but their fire resistance is a critical consideration in urban and industrial applications. Tests, such as those based on ASTM E-84 and ASTM E-119, reveal how FRP covers perform under fire exposure. The carbon or glass fibers in FRP are highly resistant to heat, maintaining strength even at high temperatures. However, the polymer matrix, typically epoxy or polyester, softens or melts at around 150°C, far below the 1,100°C reached in standard fire tests within minutes. This indicates that while fibers hold up, the matrix’s degradation can compromise structural integrity.

To enhance fire resistance, manufacturers incorporate fire-retardant resins, such as those containing halogens or bromine, which suppress flames and make covers self-extinguishing. Tests show these resins reduce flame spread rates compared to standard thermoset resins, though smoke generation remains a concern, often exceeding 750 in ASTM E-84 tests. Adding fillers like alumina tri-hydrate (ATH) at 25% or 50% by weight improves fire resistance by delaying burn-through, though it may reduce mechanical strength.

Fireproofing coatings or troweled materials can further extend performance, though aesthetic challenges arise with sprayed-on options. For recessed covers in high-risk areas, a minimum concrete cover of 64 mm is recommended to protect underlying structures. These tests highlight that while FRP covers require enhancements to meet stringent fire codes, their adaptability allows for tailored solutions, ensuring safety in applications like urban utilities or industrial flooring.