Title: Influence of Specimen Size and Fiber Content on Mechanical Properties of Ultra-High-Performance Fiber-Reinforced Concrete

Author(s): Sadegh Kazemi and Adam S. Lubell

Publication: Materials Journal

Volume: 109

Issue: 6

Appears on pages(s): 675-684

Keywords: compressive strength; flexural toughness factor; mixing energy; shear toughness factor; size effect; steel fiber; ultra-high-performance fiberreinforced concrete (UHPFRC).

DOI: 10.14359/51684165

Date: 11/1/2012

Abstract:
The influences of specimen size and fiber content on the mechanical properties of an ultra-high-performance fiber-reinforced concrete (UHPFRC) were studied. The UHPFRC was formulated with up to 5% volume fraction of short steel fibers and subjected to conventional moist curing. The mechanical properties in compression were characterized using cube and cylinder specimens. Four-point flexural tests of unnotched prism specimens and direct shear tests of notched specimens were completed. In all cases, specimens with a size range of up to 2 were used. The peak strengths and post-peak ductility in compression, flexure, and direct shear were all found to increase significantly as the fiber volume fraction increased. Normalized strengths decreased for increases in specimen size, with a more pronounced size influence found at greater fiber contents. The measured test results were further analyzed to evaluate the influence of fiber content and specimen size on flexural and shear toughness. Significant improvements in toughness were obtained for mixtures with higher fiber content.