Microfiber and Macrofiber Hybrid Fiber-Reinforced Concrete
Publication: Journal of Materials in Civil Engineering
Volume 17, Issue 5
Abstract
To realize the potential of micro- and macrofiber blends in a concrete matrix, a concrete containing polyvinyl alcohol (PVA) or steel microfibers and steel macrofibers was designed using a mixture proportioning method that provides good workability in concretes containing microfibers. This procedure is based on an optimum paste volume fraction determined from the relationship between flow and paste content. The mechanical performance, water permeability of the cracked material, and shrinkage crack resistance of cast concrete were evaluated. In the hybrid concrete, the microfibers delayed the development of macrocracks and so the composite demonstrated greater strength and crack resistance than a similar matrix reinforced with macrofibers only. This influence was less pronounced than was observed with a mortar matrix in a previous study. This is explained by differences in the failure mechanism of the fibers: A stronger fiber-matrix bond resulting from a lower water-to-binder ratio caused the microfibers to break instead of pull out. The macrofibers were also more likely to break in the hybrid fiber-reinforced concrete than in the same matrix containing macrofibers alone—since the microfibers reinforced the matrix, increasing the macrofiber pullout resistance.
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Acknowledgments
Support for this project was provided by MBT (Schwiez) AG, Zurich, Switzerland and the work was conducted at the Center for Advanced Cement Based Materials (ACBM), Northwestern University, Evanston, Ill.
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Information & Authors
Information
Published In
Journal of Materials in Civil Engineering
Volume 17 • Issue 5 • October 2005
Pages: 595 - 604
Copyright
© 2005 ASCE.
History
Received: Oct 1, 2002
Accepted: Jun 24, 2004
Published online: Oct 1, 2005
Published in print: Oct 2005
Notes
Note. Associate Editor: Nemkumar Banthia
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