Comparison of Performances of Structural Fibers and Development of a Specification for Using Them in Thin Concrete Overlays

Project Details
STATE

MN

SOURCE

MnDOT

END DATE

08/01/18

RESEARCHERS

Barman, Manik; Hansen, Bryce

SPONSORS

University of Minnesota Duluth, Department of Civil Engineering

KEYWORDS

Concrete overlays; Concrete pavements; Fiber reinforced concrete; Fibers; Flexural strength; Overlays (Pavements); Pavement joints; Pavement performance

Project description

Structural fibers improve the long-term performance of concrete pavements and overlays and potentially are useful to reduce the slab thickness. These fibers are available in different parent material compositions, stiffness, shapes, and aspect ratios. The main objective of this study was to characterize the post-crack flexural and joint performance of fiber reinforced concrete to develop a specification for the selection of structural fibers for concrete overlays and/or pavements. The study included a literature review, an online survey, and a large-scale laboratory testing. It was found that the majority (almost 94%) of the FRC overlays in this country were constructed with structural synthetic fibers, which provided equal or better performance than projects using the steel fibers. In the laboratory study, a total of 43 different mixes were prepared with 11 different types of fibers. Fiber dosage, stiffness, and geometry significantly influenced the residual strength ratio (RSR) and residual strength (RS). In general, embossed, twisted, and crimped fibers performed better on average than straight-flat synthetic fibers when the comparison was made in terms of RSR or RS. From the joint performance testing, it was found that fibers can greatly improve the performance of the pavement with respect to load transfer efficiency (LTE), differential displacement, and differential joint energy dissipation. The findings from this were used to recommend the target ranges post-crack flexural performance, and joint performance parameters.
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