Fiber-Reinforced Concrete and Performance Engineered Concrete Mixture Design

Abstract

A challenging objective for the concrete industry, in using structural fibers in concrete pavements and overlays while moving towards the implementation of the Performance Engineered Mixture (PEM) design, is to understand the influence of fibers on tests performed in the PEM design procedure. The goal of the PEM design procedure is to produce concretes that resist climate and material related distresses, such as durability cracks and concrete-degradation due to chloride-ion penetration. The addition of fibers in a concrete mixture also increases concrete durability by enhancing post-cracking performance. Using PEM procedure for fiber reinforced concrete (FRC) pavements will produce durable concrete pavements that resist environmental- and material- driven distresses as well as possess an improved post-crack performance. The objective of this research is to study the relationship between different fresh concrete properties and their influence on the hardened concrete behavior and durability. The materials used in this study includes two types of coarse aggregates, fine aggregate, two types of fiber, cement, fly ash and admixtures. Two different fiber types (twisted and embossed geometries) and two fiber dosages (4 lb/ yd3 and 7.6 lb/ yd3 ) were considered in this study. Fresh and Hardened concrete test results for all the FRC mixes were compared to results of the control plain concrete mixes. Fresh concrete tests such as slump, air content, super air meter number (SAM), Box, and V-Kelly tests were conducted. Hardened concrete properties such as compressive strength, modulus of elasticity, beam flexural strength, resistance to distresses caused by multiple freeze-thaw cycles, and surface/electrical resistivity was determined. Based on the results of this study, it was found that fiber dosages and types significantly influence the V-Kelly index, while moderately influence SAM number and box test rating. The fibers used in this study had significant influence on the post-crack behavior of concrete. The freeze-thaw durability and surface resistivity test results indicated that fibers have less influence on the concrete resistance to freeze-thaw durability issues.