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

Abstract

Structural fibers improve the long-term performance of concrete pavements and overlays and potentially are useful to
\nreduce the slab thickness. These fibers are available in different parent material compositions, stiffness, shapes, and aspect
\nratios. The main objective of this study was to characterize the post-crack flexural and joint performance of fiber reinforced
\nconcrete to develop a specification for the selection of structural fibers for concrete overlays and/or pavements. The study
\nincluded a literature review, an online survey, and a large-scale laboratory testing. It was found that the majority (almost
\n94%) of the FRC overlays in this country were constructed with structural synthetic fibers, which provided equal or better
\nperformance than projects using the steel fibers. In the laboratory study, a total of 43 different mixes were prepared with 11
\ndifferent types of fibers. Fiber dosage, stiffness, and geometry significantly influenced the residual strength ratio (RSR) and
\nresidual strength (RS). In general, embossed, twisted, and crimped fibers performed better on average than straight-flat
\nsynthetic fibers when the comparison was made in terms of RSR or RS. From the joint performance testing, it was found that
\nfibers can greatly improve the performance of the pavement with respect to load transfer efficiency (LTE), differential
\ndisplacement, and differential joint energy dissipation. The findings from this were used to recommend the target ranges
\npost-crack flexural performance, and joint performance parameters