Experimental Investigation of the FRCM/Concrete Interfacial Debonding

1 graduate student (visiting scholar who is a PhD student at the University of Padova)

The objective of this project is to study the bond behavior of fiber reinforced cementitious matrix (FRCM) composites externally bonded to reinforced concrete (RC) members. This research will be focused on composites comprised of bidirectional polyparaphenylene benzobisoxazole (PBO) fibers embedded in a cementitious matrix material from a commercially available source. Single-lap shear tests will be conducted to examine the influence of various parameters including composite length, composite width, matrix thickness, and number of layers of fiber on the load transfer between the composite and concrete substrate.  The ultimate goal is to study the bond characteristics and failure mechanisms of FRCM composites applied externally to the surface of RC structures, such as those in civil infrastructure, for the purpose of structural strengthening.

This project will study the bond behavior of fiber reinforced cementitious matrix (FRCM) composites externally bonded to reinforced concrete (RC) members. Fiber-reinforced composite systems are widely used for strengthening, repairing, and rehabilitation of reinforced concrete structural members. A promising newly-developed type of composite, comprised of fibers and an inorganic cement-based matrix, provides several environmental, structural, and sustainability-related advantages over fiber reinforced polymer (FRP) composites traditionally used in structural applications, which potentially expands the strengthening applications beyond those currently utilized. Such advantages include: 1) high resistance to fire and high temperatures; 2) resistance to UV radiation; 3) ease of handling during the application because the inorganic binder is water-based; 4) easy cleanup and reuse of tools; 5) low odor and toxin emissions during application and curing; 6) permeability compatibility with the concrete substrate; and 7) unvarying workability time (between 40°F and 105°F). Stress-transfer mechanisms and interfacial fracture propagation of fiber-reinforced composites externally-bonded to a concrete substrate are complex phenomena that are highly dependent on the bond characteristics of the composite matrix material to the fibers. These phenomena have not yet been clearly defined and understood for FRCM composites. Experimental work will be carried out in this study to isolate the shear debonding phenomenon using single lap shear tests.

Relationship to other Research/Projects

CIES GRA project to support visiting scholar, Tommaso D’Antino

Transportation-Related Keywords

Technology Transfer Activities

Results of this study will be disseminated through a presentation and poster at the CIES/NUTC conference at Missouri S&T and at least one technical peer-reviewed journal article.

Project Deliverables

Anticipated Benefits

Research on FRCM composites for RC strengthening is in its infancy. Results of this pilot study will shed light on the bond behavior and will serve as the basis for and add credibility to future proposals on bond and stress transfer mechanisms, with high potential for collaboration with leading researchers in this field. Dr. Sneed and Dr. Carloni recently conducted an NSF-sponsored workshop entitled Future Directions in Composite Strengthening Applications, and the topic of FRCM composites was of high interest to the participants.

Milestones