Assessment of Thermal Damage in Hybrid Fiber-Reinforced Concrete
Publication: Journal of Materials in Civil Engineering
Volume 22, Issue 9
Abstract
Three-point bending tests on high-strength concrete specimens after exposure to high temperatures are presented, with a detailed evaluation of process zone size. The variables considered for the high-strength concrete were the types of fiber reinforcement: steel microfibers, polypropylene microfibers, and a hybrid combination of steel and polypropylene microfibers. Both virgin (no heat related damage) and heat treated specimens were tested by conducting experiments at ambient conditions approximately one month after exposure to the high temperature. For both undamaged and heat treated specimens, acoustic emission monitoring and high-resolution interferometric measurements were used to characterize the evolution of the finite size of the process zone as a function of the applied load. The size and shape of the localized damage zone due to prepeak microcracking are two of the significant factors influencing the strength of quasibrittle materials, i.e., the structural scaling. This paper reveals that the material ductility increases with the thermal damage, which is explained by the increase in the fracture process zone size. As a consequence, a correct interpretation of the experimental data requires an identification of fracture parameters through indirect methods.
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Acknowledgments
The writers wish to extend their gratitude to Professor Luca Bertolini and Dr. Gian Luca Guerrini for many helps concerning the experimental program. The writers would also like to thank the technical staff of the Structures Laboratory at Politecnico di Milano, particularly Paolo Broglia, Antonio Cocco, Daniele Spinelli, and Marco Cucchi for their assistance during the experimental work.
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Information
Published In
Journal of Materials in Civil Engineering
Volume 22 • Issue 9 • September 2010
Pages: 836 - 845
Copyright
© 2010 ASCE.
History
Received: Dec 22, 2008
Accepted: Dec 13, 2009
Published online: Dec 28, 2009
Published in print: Sep 2010
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