Journal
CONSTRUCTION AND BUILDING MATERIALS
Volume 250, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2020.118723
Keywords
CaO-based expansive agent; MgO-based expansive agent; Concrete-filled steel tube; Deformation; Mechanical property
Categories
Funding
- National Key R&D Program of China [2017YFB0310100]
- Key Project of Natural Science Foundation of China [51738004]
- National Science Foundation of China [U1706222]
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The separation problem between core concrete and steel tube is one of the main bottlenecks restricting the construction of super large-span concrete-filled steel tubular arch bridges. One of the main measures to solve this problem is to prepare micro expansive core concrete by using the shrinkage compensation property of expansive agent. This study investigated the deformation and mechanical properties of core concrete containing CaO-based and MgO-based expansive agent under both the constant temperature and the varying temperature. The results showed that concrete containing CaO-based and MgO-based expansive agents can produce remarkable expansion which increases with the increase of CaO-MgO ratios under the constant temperature of 20 degrees C, but decreases with the increase of CaO-MgO ratios under the varying temperature. Through the restraint from the steel tube can reduce the expansion value, proper selection of CaO-MgO ratio can still produce enough expansion in core concrete to compensate autogenous and thermal shrinkage, with the concrete still in expansion state when the temperature finally stabilizes. Thus it is beneficial to maintain the integrity between the core concrete and the steel tube. The results obtained will provide guidance for the application of this kind of expansive agent in concrete-filled steel tube structure. (C) 2020 Elsevier Ltd. All rights reserved.
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