Title: Cementitious Resins for Strengthening Reinforced Concrete Beams with NSM CFRP

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

Publication: Structural Journal

Volume:

Issue:

Appears on pages(s):

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

DOI: 10.14359/51738720

Date: 3/23/2023

Abstract:
This paper presents the feasibility and relevance of cementitious resins as a bonding agent for near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) strips. Contrary to conventional organic matrices, 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 are represented 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, thereby altering 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.