Title: Effect of Fiber Type and Content on Behavior of UHPFRC for Prestressed Girder Repair

Author(s): Banik

Publication: Web Session

Volume: ws_S22_Banik.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
Ultra-high-performance-fiber-reinforced concrete (UHPFRC) is a cementitious material with high compressive strength, densely packed structure resulting in near-zero permeability, small crack opening, and significant post-cracking tensile strength. UHPFRC has both mechanical properties and durability exceeding those of normal strength concrete. However, these properties come with a substantial material cost, with most of the cost associated with the fiber amounts. In this research, the effect of both fiber content and type (varying both in aspect ratio and material) on UHPFRC properties have been studied using varying fiber percentages by volume in a non-proprietary UHPFRC developed at the University of Oklahoma. UHPFRC compression, flexure, direct tensile, and splitting tensile behaviors emphasizing strain responses have been examined in this study. To better understand the fiber bridging property, fiber pullout from the concrete matrix has been studied as part of the research. Also, the study of flexure behavior of UHPFRC subjected to freezing-thawing cycles in both induced-cracked and uncracked specimens is undertaken to better understand the effect of initial cracking on durability. Furthermore, UHPFRC was used to retrofit a half-scale AASHTO type-II prestressed girder which was failed using a point load positioned to induce bond shear failure. The beams were then repaired by encapsulating the failure zone with UHPFRC with a 2% fiber content. Though this process did not restore the prestress, it successfully restored the original shear capacity and created an impermeable layer to prevent water ingress into the existing cracks.