Title:
Effect of Beam Size, Casting Method, and Support Conditions on Flexural Behavior of Ultra-High-Performance Fiber-Reinforced Concrete
Author(s):
Kay Wille and Gustavo J. Parra-Montesinos
Publication:
Materials Journal
Volume:
109
Issue:
3
Appears on pages(s):
379-388
Keywords:
bending strength; fiber orientation; flexural strength; residual strength; self-consolidating; steel fibers; ultra-high-performance concrete (UHPC); ultra-high-performance fiber-reinforced concrete (UHP-FRC).
DOI:
10.14359/51683829
Date:
5/1/2012
Abstract:
The flexural behavior of fiber-reinforced concretes (FRCs) is typically evaluated through standard tests of beams under either three-or four-point loading. Although these test methods are standardized, test results could vary significantly depending on specimen size, concrete casting method, and support devices used. Results from a comprehensive experimental program aimed at evaluating the influence of these test parameters on material flexural behavior are presented. The investigation focused on ultra-high-strength (>150 MPa [22 ksi]) FRC, typically referred to as ultra-high-performance FRC (UHP-FRC). By varying specimen size, casting method, and support conditions to account for those normally used by researchers in accordance with ASTM C1609/C1609M and RILEM TC 162-TDF, equivalent bending strengths as low as 10 MPa (1.4 ksi) and as high as 29 MPa (4.2 ksi) were obtained using the same UHP-FRC mixture design. The degree of restraint developed at the supports intended to work as rollers was also evaluated through finite element analyses. The use of a shear friction coefficient of 0.4, which was found to be representative of that in the “high-friction” supports used in this study, led to an increase in bending strength of approximately 30% compared to beams with no axial restraint. The test results also indicate that a more specific recommendation on the casting method is needed when using highly workable FRC, given the variability in results between beams constructed following various casting methods.