Zeitabhängiges Verbundverhalten von Faserkunststoffbewehrung

Long-time bond behaviour of fibre-reinforced polymer

Due to their high resistance to environments that promote steel corrosion, fiber-reinforced polymers (FRP) offer significant potential for producing durable and low-maintenance concrete structures. However, FRP materials are subject to chemical and physical degradation over time, which can lead to a reduction in mechanical performance. This degradation is influenced by the properties of the fibers and polymer matrix, the fiber-matrix interface, and exposure to environmental factors. As a result, the time-dependent material behavior has a direct impact on the structural performance and deformation characteristics of FRP-reinforced concrete elements. While current research on the long-term behavior of FRP has primarily focused on its tensile properties, studies addressing the time-dependent bond behavior between FRP and concrete remain limited. This paper investigates the time-dependent bond behavior of FRP reinforcement in concrete. It begins with an analysis of the underlying damage mechanisms, followed by the presentation of a testing methodology specifically developed to capture time-related bond degradation. Experimental results are provided for sand-coated FRP bars subjected to temperature, moisture, and concrete alkalinity. The objective of the study is to derive a time-dependent bond strength suitable for structural design over a service life of up to 100 years under relevant in-service temperature conditions.