High-Performance Fiber Reinforced Concretes in Virginia

Abstract

High-performance fiber reinforced concretes (HPFRCs) provide high workability, high compressive and tensile strengths, high ductility, and high durability. They exhibit strain and deflection hardening. The Virginia Department of Transportation (VDOT), U.S., has been experimenting with various types of HPFRC, including high early strength versions, to control cracking in transverse and longitudinal connections, shear keys, blockouts that connect adjacent members, overlays, and inverts of corrugated metal pipe culverts. This paper presents laboratory and field work using three classes of HPFRC for different VDOT applications. They have high ductility and very low permeability. In addition, Class I has normal compressive strength, Class II has high compressive strength, and Class III has high early compressive strength. Laboratory work consisted of preparing and testing of in-house or prepackaged HPFRC with varying ingredients and proportions using compression, indirect tension, flexure, and pull-out tests. Synthetic and steel fibers were added in different amounts. Mixtures were prepared in the mortar or pan mixers that produce good fiber dispersion. Laboratory and field testing indicated that all three classes of HPFRC had high ductility; strengths varied according to the class. Engineered cementitious composite in Class I had normal strength, ultra-high-performance concrete in Class II had the highest strength, and concretes in Class III had high early strength, enabling minimal traffic interruption. HPFRC selected from an appropriate class can be used successfully to enable early opening to traffic, provide a short splice length, achieve satisfactory adjacent member connections, and restrict crack width for a longer service life.