Residual Resistance of Non-Mechanical Prestressed CFRP Anchorages Subjected to Environmental Conditions

Abstract

Flexural strengthening of reinforced concrete (RC) elements with prestressed Carbon Fiber Reinforced Polymers (CFRP) as an externally bonded reinforcement (EBR) has gained increasing popularity over the last years. Opposite to conventional mechanical anchorages, the gradient anchorage is a purely bond-based technique. It is achieved by utilizing the fast curing property of epoxy under high temperatures together with a segment-wise prestressing force release at both strip ends. The short-term performance of the gradient anchorage has been previously investigated and its underlying force transfer mechanisms have been explained. The current study focuses on the durability and long-term performance under the influence of varying environmental conditions as this occurs in real-world structures during service. For this purpose, a special experimental setup has been designed with the aim to ensure a constant interfacial shear force between CFRP-epoxy-concrete prior to accelerated ageing conditions. Special attention is put on freeze-thaw cycles in combination with carbonation as well as elevated temperature and high relative humidity. First results of reference and carbonation cases are reported and discussed in this paper.