# Fire Performance of FRP-Composites and Strengthened Concrete Structures: A State-of-the-Art Review

## TL;DR

This paper reviews how fiber-reinforced polymer (FRP) materials and FRP-concrete systems behave under fire conditions, highlighting challenges and solutions for fire safety in these structures.

## Contribution

The paper distinguishes fire behavior between internal and external FRP reinforcement systems and evaluates fire-protection strategies.

## Key findings

- The glass transition temperature Tg plays a critical role in the thermal degradation of FRP materials.
- External insulation thickness is the main factor affecting fire survival time in EBR/NSM systems.
- Polymer matrix thermal degradation is a major obstacle for post-fire recovery of FRP-reinforced structures.

## Abstract

The structural application of Fiber-Reinforced Polymers (FRP) is significantly hindered by their inherent thermal sensitivity. This paper presents a comprehensive review of the fire performance of FRP materials and FRP-concrete systems, spanning from material-scale degradation to structural-scale response. Distinct from previous studies, this review explicitly distinguishes between the fire behavior of internally reinforced FRP-reinforced concrete members and externally applied systems, including Externally Bonded Reinforcement (EBR) and Near-Surface Mounted (NSM) techniques. The thermal and mechanical degradation mechanisms of FRP constituents—specifically reinforcing fibers and polymer matrices—are first analyzed, with a focused discussion on the critical role of the glass transition temperature Tg. A detailed comparative analysis of the pros and cons of organic (epoxy-based) and inorganic (cementitious) binders is provided, elaborating on their respective bonding mechanisms and thermal stability under fire conditions. Furthermore, the effectiveness of various fire-protection strategies, such as external insulation systems, is evaluated. Synthesis of existing research indicates that while insulation thickness remains the dominant factor governing the fire survival time of EBR/NSM systems, the irreversible thermal degradation of polymer matrices poses a primary challenge for the post-fire recovery of FRP-reinforced structures. This review identifies critical research gaps and provides practical insights for the fire-safe design of FRP-concrete composite structures.