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Title: Time-Dependent Bond of Concrete and Near-Surface- Mounted Carbon Fiber-Reinforced Polymer with Inorganic Resins

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

Publication: Structural Journal

Volume: 120

Issue: 1

Appears on pages(s): 61-74

Keywords: carbon fiber-reinforced polymer (CFRP); inorganic resins; interface; rehabilitation; strengthening

DOI: 10.14359/51734825

Date: 1/1/2023

This paper presents the time-dependent interfacial behavior of near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) strips bonded to a concrete substrate using inorganic resins. Four types of bonding agents (mortar, polyester-silica, ultra-high-performance concrete [UHPC], and geopolymer) are tested to appraise the potential for NSM application with a focus on rheological and mechanical performance during a curing period of 28 days. Unlike the case of the mortar and geopolymer resins, the rheological resistance of the polyester-silica and UHPC resins increases within 30 minutes, owing to an evolved setting process. The hydration of mortar continues for up to 28 days of curing in line with assorted chemical reactions. The compressive strength of polyester-silica gradually ascends to 35 MPa (5076 psi) at 28 days, while that of UHPC rapidly rises to 95.3 MPa (13,822 psi) at 3 days. Contrary to the stabilized interfacial capacity of the specimens with mortar and geopolymer after 7 days, the capacity of the specimens with polyester-silica steadily develops until 28 days. Unlike the failure mode of other cases over time, a shift in the plane of failure is noticed for the mortar-bonded interface. The post-peak response and energy dissipation of the interface are controlled by the resin type and curing period. Analytical modeling quantifies the level of hazard and clarifies the functional equivalence of the interface with the inorganic resins against conventional organic epoxy resins.