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Title: Cementitious Resins for Strengthening Reinforced Concrete Beams with Near-Surface-Mounted Carbon Fiber- Reinforced Polymer

Author(s): Yail J. Kim and Wajdi Ammar

Publication: Structural Journal

Volume: 120

Issue: 4

Appears on pages(s): 137-149

Keywords: carbon fiber-reinforced polymer (CFRP); cementitious resins; near-surface-mounted (NSM); rehabilitation; retrofit; strengthening

DOI: 10.14359/51738720

Date: 7/1/2023

This paper presents the feasibility and relevance of cementitious resins as bonding agents for near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) strips. Contrary to conventional organic matrixes, such inorganic resins offer promising performance when subjected to aggressive environments, especially under thermal distress. Three emerging resins are employed (polyester-silica, ultra-high-performance concrete [UHPC], and geopolymer) to strengthen reinforced concrete beams alongside NSM CFRP. After stochastically simulating various levels of pitting corrosion for a period of 100 years, the outcomes arerepresented in the beams by reducing the cross-sectional area of steel reinforcement before applying the rehabilitation system. The emphasis of experimental investigations lies in the workability of those resins and the flexural response of the retrofitted beams. Material-level testing reveals that the rheological properties of the resins are not related to their compressive strength. As far as load-carrying capacity is concerned, the beams bonded with polyester-silica outperform the beams with other resins; however, UHPC enables stable degradation over the years. The interfacial characteristics of the resins dominate the mechanical interaction between the damaged internal reinforcing steel and CFRP, therebyaltering the tendency of capacity drops, post-yield plateaus, and crack distributions. Through analytical modeling, the provisions of existing design guidelines are evaluated, and a modification factor is suggested to promote the cementitious resins for NSM CFRP.