Min Ook Kim, Graduate Research Assistant Department of Civil and Environmental Engineering
Amanda Christine Bordelon, Ph.D., P.E., Assistant Professor-Department of Civil and Environmental Engineering, University of Utah, ISCP Member and ISCP Past Editor
ABSTRACT:
Previous field studies suggested that macro-fibers incorporated in thin overlay pavements will result in reduced crack opening widths, vertical deflections, and debonding rates compared to that of unreinforced overlays. A simple finite element (FE) model was developed and utilized in this study to investigate how fracture energy can affect the cracking and debonding of thin concrete overlays subjected to environmental loads. It was confirmed that crack opening width, vertical lift-off, and debonding rate all decrease as the fracture energy across a joint increases or as the interfacial tensile bond increases. The developed FE model also used to make a comparison between fiber-reinforcement and dowel-bar reinforcement across a joint. With larger amounts of reinforcement across the joint, either by higher fiber contents or by larger diameter dowels, the crack opening width, vertical lift-off and debonding rates were all reduced.
Experimental tests were carried out to measure the tensile and shear bond strengths of an interface between an aged concrete and a newly cast fiber reinforced mortar overlay. It was found that the tensile interfacial energy increased with fiber-reinforcement; however, the interfacial fracture occurred through the overlay mixture and was proportional to the number of fibers which intersected the fracture path near this interface. It was confirmed that no statistical trend could be found between the tensile or shear bond properties and the addition of fibers. Overall, a reduction in debonding exhibited in the field was explained because the fiber-reinforcement reduced curling-induced lift-off, according to the finite element results.
To read the entire report, please go to: http://www.ugpti.org/resources/reports/downloads/mpc17-319.pdf
Sponsored by the Mountain Plains Consortium (MPC) 17-319: The MPC is a University Transportation Center sponsored by the U.S. Department of Transportation serving the Mountain-Plains Region of the USA—includes: Colorado State University; University of Colorado Denver; University of Denver; North Dakota State University; South Dakota State University; Utah State University; and University of Wyoming University of Utah.