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Advances in Materials Science and Engineering
Volume 2018 (2018), Article ID 3701682, 9 pages
https://doi.org/10.1155/2018/3701682
Research Article

Investigation of Microstructural Damage in Ultrahigh-Performance Concrete under Freezing-Thawing Action

1College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310023, China
2Key Laboratory of Civil Engineering Structures and Disaster Prevention and Mitigation Technology of Zhejiang Province, Zhejiang University of Technology, Hangzhou 310023, China
3School of Materials Science and Engineering, Southeast University, Nanjing 211189, China

Correspondence should be addressed to Liping Guo; moc.361@196gnipiloug

Received 9 January 2018; Revised 21 February 2018; Accepted 12 March 2018; Published 5 April 2018

Academic Editor: Antonio Gilson Barbosa de Lima

Copyright © 2018 Chunping Gu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This work aims to investigate the damage in ultrahigh-performance concrete (UHPC) caused by freezing-thawing action. Freezing-thawing tests were carried out on UHPCs with and without steel fibers. Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X-ray computed tomography (X-ray CT) were applied to detect the microstructure of the UHPC matrix before and after the freezing-thawing tests. The results showed that UHPC possessed very excellent freezing-thawing resistance due to its dense microstructure. After the freezing-thawing action, cracks occurred and were prone to initiate at the sand-paste interface in the UHPC matrix. MIP results also indicated that cracks appeared in the UHPC matrix after the freezing-thawing action. The number of defects that can be seen by X-ray CT increased in UHPC after the freezing-thawing action as well. The mismatch of the thermal expansion coefficients of the aggregate and the paste is considered to be the reason for the cracking at the sand-paste interface. The steel fibers in UHPC inhibited the propagation of cracks in the matrix and improved the freezing-thawing performance of UHPC.