In modern society, we find that the majority of our infrastructure (buildings, bridges, tunnels, etc.) is made of aging concrete. A recently developed cost effective method of maintaining this infrastructure is the outer coating with fiber reinforced polymer (FRP) composites. But is it a temporary patch or a lasting solution? Little research has looked into this question. Now, a 13-year study published in Composites Part B finally discover, bringing us a little closer to the widespread use of this solution.
In FRP concrete reinforcement, glass or carbon fiber reinforced polymer composites (GFRP or CFRP) are bonded to concrete using an epoxy adhesive. These sheets provide additional support and strengthen concrete structures by protecting them from harsh environmental conditions, such as humidity levels and high temperatures. But the problem is, these same environmental conditions can potentially degrade the concrete-FRP bond, causing the FRP protection system to fail prematurely.
Professor Jaeha Lee of Korea Maritime and Ocean University, principal investigator in the 13-year study, said: “The information available on the behavior of the FRP-concrete bond after sustained loads in different environments is very limited, in particularly for periods exceeding two years. “
The researchers tested the CFRP and GFRP systems under a variety of indoor and outdoor environmental conditions for the change in a parameter called the onset of peel stress. It is a measure of the strain that occurs before failure; heavier stresses are generally preferred to prevent failure.
The researchers found that environmental conditions had a significant impact on bond behavior. After 13 years, greater reductions in separation stresses were observed in the exterior beams than in the interior beams. In addition, the bonding behavior varied between materials: changes in peel strain were negligible in interior CFRP beams, while in interior FRP beams there was a noticeable decrease.
Professor Lee emphasizes the importance of these tests for future use, stating, “If the long-term durability of concrete-FRP interfaces is assessed, the use of this reinforcement system is expected to increase with minimal investment. a safer city by minimizing the risk of collapse or damage to existing structures. “
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Material provided by Korea National Maritime and Ocean University. Note: Content can be changed for style and length.