Innovative Strengthening for Deteriorated Concrete Bridges Using Embedded Composite Sheets Bonded with Polyester-silica

Structural strengthening of deteriorated concrete bridges using advanced composite materials such as carbon fiber reinforced polymer (CFRP) has gained significant attention from the infrastructure engineering community. CFRP may be bonded along the tensile substrate of a concrete member with an epoxy adhesive to upgrade the load-carrying capacity of the member. Numerous advantages are expected when a structural member is retrofitted with CFRP sheets; for instance, insignificant increase in dead load, high-strength and favorable modulus, resistance to corrosion and fatigue, and reduced maintenance costs. Although CFRP-strengthening has been broadly used for buildings and bridges over the last decade, it is recognized that premature bond failure is a critical concern, which would substantially reduce the efficacy of structural strengthening. A number of research projects were conducted to understand the bond failure mechanism of CFRP-strengthened concrete beams and to propose enhanced implementation methods (Bank 2006). The current state-of-the-art of debonding-control includes use of anchorage that can retard the failure of CFRP-concrete interface (Kalfat et al. 2013). Various types of anchor systems were suggested previously such as mechanical anchors (Ortega 2007), non-mechanical anchors (Kim et al. 2008), and CFRP Uwraps (Pham and Al-Mahaidi 2006). These approaches, however, are not a permanent solution because i) mechanical anchors are susceptible to corrosion that can cause secondary distress to the bonded CFRP; ii) non-metallic anchors need extra endeavors and will eventually fail when excessive mechanical stresses are associated; and iii) CFRP U-wraps can also debond from the concrete. An intrinsically different approach is essential to address the critical debonding problem in externally-bonded CFRP application. A holistic research program integrating experimental and theoretical investigations is proposed to develop an innovative debonding-control method for CFRP-strengthened concrete members without using external anchorage. Unlike conventional strengthening approaches employing CFRP sheets bonded to the surface of concrete, the novel idea is that wide grooves are cut near both ends of a concrete member and CFRP sheets are embedded so that stress concentrations 2 causing end-peeling failure are mitigated. It is important to note that this approach is different from existing near-surface-mounted (NSM) application that requires long grooves for CFRP strips. A grouting agent made of polyester-silica will be used to fill the gap between the embedded CFRP and the concrete substrate. The polyester-silica resin is believed to be a strong candidate providing sufficient bond to the CFRP-concrete interface. The proposed concept for debonding-control of externally bonded CFRP sheets has not been exploited by others previously and thus will advance the state-of-the-art of rehabilitation technologies.

Language

  • English

Project

  • Status: Active
  • Funding: $99015
  • Contract Numbers:

    DTRT13-G-UTC38

  • Sponsor Organizations:

    Research and Innovative Technology Administration

    Department of Transportation
    1200 New Jersey Avneue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Kline, Robin

  • Performing Organizations:

    University of Colorado Denver

    Denver, Colorado  United States  80204
  • Principal Investigators:

    Kim, Yail

  • Start Date: 20160721
  • Expected Completion Date: 20180731
  • Actual Completion Date: 0
  • Source Data: MPC-516

Subject/Index Terms

Filing Info

  • Accession Number: 01607378
  • Record Type: Research project
  • Source Agency: Mountain-Plains Consortium
  • Contract Numbers: DTRT13-G-UTC38
  • Files: UTC, RiP
  • Created Date: Aug 2 2016 3:31PM