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

AbstractThis 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 f...

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Bibliographic Details
Published in:Journal of materials in civil engineering 2018-04, Vol.30 (4)
Main Authors: Meng, Weina, Khayat, Kamal H
Format: Article
Language:English
Subjects:
Building materials
Civil engineering
Consolidation
Dietary fiber
Flexural strength
Mechanical properties
Polyvinyl alcohol
Shrinkage
Synthetic fibers
Technical Papers
Tensile strength
Toughness
Ultra high performance concrete
Viscosity
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Summary:AbstractThis 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.
ISSN:0899-1561
1943-5533
DOI:10.1061/(ASCE)MT.1943-5533.0002212