Document Type : Original Article
Authors
1
Faculty of Engineering, Zagazig University, Zagazig, Egypt
2
The Petroleum Projects and Technical Consultations Company (PETROJET), New Cairo, Cairo, Egypt
3
Faculty of Engineering, University of Zawia 16418, Libya
4
Housing & Building National Research Centre, Dokki, Giza, Egypt
Abstract
This work presents the mechanical and durability evaluation of high-performance concrete, HPC, mixes, used for tunnels, after exposed to different temperatures. Nine HPC mixes were investigated. The first group has W/C ratios; 0.25, 0.31 and 0.37. Second group has silica fume addition by about 5.0%, 10%, and 15% of cement weight. In the second one, the polypropylene fibers were added to concrete by the ratios of 0.211% from the concrete volume. The mechanical properties were measured at room temperature and after subjected to 400°C and 800°C for curing periods of 28 and 56 days. The durability was evaluated by water penetration depth at room temperature (RT). SEM micrographs results were, also, investigated. The results indicate that at temperature of 400°C, the compressive strength of the concrete increased. With further increases in temperature over 400°C to 800°C, they decreased. At 400°C, the highest compressive strength improvement is achieved by about 18.2% after 56 days curing in the case of 10% SF, while with addition of PP=0.211 fibers, Fc has a significant increase after curing for 56 days by about 32.1%. Moreover, at 800°C, the highest tensile strength improvement achieves by about 87.5% after curing for 56 days in the case of SF=10%. The lowest porous penetration depth of water was found for mix containing W/(C+SF) = 0.37, SF=10%, and PP=0.211%.
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