In the relentless pursuit of enhancing the durability and safety of concrete structures, a team of researchers led by Xu Liang from the Research Institute of Urbanization and Urban Safety at the University of Science and Technology Beijing, along with the School of Ocean and Civil Engineering at Shanghai Jiao Tong University, has made a significant breakthrough. Their study, published in *Case Studies in Construction Materials* (which translates to *典型建筑材料研究*), introduces a novel high-temperature resistant glass fiber-reinforced polymer (GFRP) bar that could revolutionize the construction industry, particularly in fire-prone environments.
The research addresses a critical challenge in the use of GFRP bars: their rapid deterioration at elevated temperatures. Traditional GFRP bars, while excellent for solving corrosion and durability concerns, lose mechanical properties quickly when exposed to high temperatures, limiting their widespread application. To overcome this, the team developed a modified vinyl ester (VE) resin with a high glass transition temperature (Tg) to serve as the matrix material for the GFRP bars.
The study investigated the thermal stabilities of both the modified and unmodified VE resins and the tensile performance of the GFRP bars at various temperatures, ranging from ambient conditions to a scorching 550°C. The results were promising. The modified VE resin demonstrated superior thermal stability and flame-retardant properties. The GFRP bars showed remarkable resilience, retaining 90.6% of their tensile strength at 150°C, 84.2% at 300°C, and an impressive 68.0% at 400°C. Even at 550°C, they retained 9.9% of their strength, highlighting their stability at high temperatures.
“These findings underscore the potential of modified GFRP bars to enhance the fire resistance of concrete structures,” said Xu Liang, the lead author of the study. “The ability of these bars to retain a significant portion of their tensile strength at elevated temperatures opens up new possibilities for their use in high-risk environments.”
The research didn’t stop at laboratory tests. The team implemented a real-world engineering application to demonstrate the practical utility of these modified GFRP bars. They designed preliminary parameters for GFRP reinforcement with a concrete cover thickness of 67 mm and a spacing of 500 mm between bars, based on standard requirements. Finite element analysis was then performed to simulate the behavior of the structure under a 90-minute fire exposure, in compliance with fire resistance rating requirements for concrete slabs.
The results confirmed that the GFRP bars retained their ability to resist fire loads even after steel reinforcement failed. This underscores the importance of maintaining adequate concrete cover thickness when using these modified GFRP bars. “This study provides critical insights for the broader adoption of fire-resistance GFRP bars in structural engineering,” Liang added. “It highlights the potential for these materials to enhance safety and durability in fire-prone environments.”
The implications for the energy sector are substantial. Structures in high-risk areas, such as power plants and refineries, could benefit greatly from the enhanced fire resistance offered by these modified GFRP bars. The ability to maintain structural integrity during fires could prevent catastrophic failures, saving lives and reducing downtime.
As the construction industry continues to evolve, the adoption of advanced materials like these modified GFRP bars could become a standard practice. This research not only addresses a critical need but also paves the way for future developments in the field, ensuring safer and more durable structures in the face of increasingly challenging environmental conditions.