Effect of Hybrid Fibers on Fresh Properties, Mechanical Properties, and Autogenous Shrinkage of Cost-Effective UHPC


This paper investigates the effects of hybrid micro-macro steel and micro steel blended with synthetic fibers and of the fiber content on key properties of a cost-effective ultrahigh-performance concrete (UHPC). Eleven mixtures are prepared using three types of fibers: micro steel straight fibers (SF), macro steel hooked-end fibers (HF), and polyvinyl alcohol (PVA) fibers. The fiber content of SF is increased from 0 to 5%. At a fiber content of 2%, different combinations of micro-macro steel and micro steel-PVA fibers are considered. The minislump flow of all mixtures is fixed to 280 ± 10 mm by adjusting the high-range water reducer (HRWR) dosage to ensure self-consolidating characteristics. The investigated properties include the HRWR demand, plastic viscosity, compressive strengths, tensile and flexural properties, and autogenous shrinkage. The plastic viscosity increases with the steel fiber content. At a fiber content of 2%, increasing the content of PVA or HF increases the plastic viscosity. Compared with the reference UHPC mixture made with 2% SF, the incorporation of 1% SF and 1% HF increases the flexural strength, toughness, and tensile strength by approximately 25, 30, and 20%, respectively, and reduces the autogenous shrinkage by 25%. The addition of 1.5% SF and 0.5% PVA increases the flexural strength and toughness by 10 and 15%, respectively, and decreases autogenous shrinkage by 40%. Increasing the SF content from 2 to 5% does not significantly improve the flexural properties, but notably reduces autogenous shrinkage.


Civil, Architectural and Environmental Engineering


This research was funded by RE-CAST Tier-1 University Transportation Center at Missouri University of Science and Technology (Grant No. DTRT13-G-UTC45) and the Energy Consortium Research Center at Missouri Science and Technology (Grant No. SMR-1406-09).

Keywords and Phrases

Bending strength; Compressive strength; Concretes; Cost effectiveness; Fibers; Mechanical properties; Mixtures; Shrinkage; Tensile strength; Viscosity; High range water reducer; Hybrid fibers; Poly (vinyl alcohol) (PVA); Rheological properties; Self-consolidating concrete; Tensile and flexural properties; Ultra high performance concretes (UHPC); Ultrahighperformance concretes (UHPC); Steel fibers; Concrete; Mechanical property; Rheology; Shrinkage; Steel

International Standard Serial Number (ISSN)

0899-1561; 1943-5533

Document Type

Article - Journal

Document Version


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© 2018 American Society of Civil Engineers (ASCE), All rights reserved.

Publication Date

01 Apr 2018