Optimization of microstructure and pullout behavior of fibers in ultra-high strength concrete with the help of nano-particles and heat curing

Author(s): Zemei Wu, Caijun Shi, K.H. Khayat, Deju Zhu
Paper category: Proceedings
Book title: 1st International Conference on UHPC Materials and Structures
Editor(s): Caijun Shi and Dehui Wang
ISBN: 978-2-35158-164-3
e-ISBN: 978-2-35158-165-O
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: 479-491
Total Pages: 13
Language: English

Abstract: The incorporation of nano-particles can have significant effects on the microstructure and performance of cement-based materials. In this paper, the effects of nano-CaCO3 and nano-SiO2 on flowability, heat of hydration, compressive and flexural strengths, hydration products, pore structure, and pullout behavior of fiber-matrix in ultra-high strength concrete (UHSC) were investigated. Hot water curing was implemented to improve the properties. The results indicated that the incorporation of nano-particles decreased the flowability and increased the heat of hydration. The early-age compressive strength of UHSC with 1% nano-silica was slightly greater than that with 3.2% nano-CaCO3. Their strengths were comparable at later ages after 28 d. For pullout behavior of fibers, UHSC with nano-CaCO3 showed comparable bond properties to that with nano-SiO2 at early ages up to 7 d. However, hardening slip behavior with significant improvement in bond strength and toughness were observed for UHSC with nano-CaCO3 at later ages after 28 d. Hot water curing up to 3 d was shown to greatly improve the strength of the matrix and bonding properties to fiber. However, the strength would decrease when overlong hot curing was adopted due to introduction of weak zone associated with thermal expansion.

Online publication: 2016
Publication type : full_text
Public price (Euros): 0.00