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Instant mechanical recovery of heat-damaged nanosilica-incorporated cement composites under various rehydrations procedures

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Abstract

In this work, the instant mechanical recovery and the thermal resistance of nanosilica(NS)-incorporated cement composites were investigated. The composites were exposed to various heating temperatures (200, 500, 800, and 1000 °C) and rehydration conditions (25 °C/65% RH or water rehydration), and weight, surface morphology, density, compressive strength, and X-ray diffraction were assessed. 29Si nuclear magnetic resonance was used to analyze the relationship between the mean chain length (MCL) of calcium silicate hydrates (C–S–H) and instant mechanical recovery. Increasing the NS content substantially increased the compressive strength after heating and strength recovery through rehydration at 25 °C/65% RH, particularly after exposure at 500 and 800 °C. The NS pozzolanic reaction afforded strength recovery and was linearly related to increasing MCL of C–S–H. The pozzolanic reaction produced a compact matrix; therefore, the strength recovered considerably following rehydration in water, even after heating to 800 °C, because of the combined effect of hydrate formation and the resistance of the matrix to thermal shock.

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Acknowledgements

The authors acknowledge the support provided by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (NRF-2020R1A4A1019074).

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  1. Department of Architectural Engineering, Hanyang University, Seoul, 04763, Korea

    Heongwon Suh, Sumin Im & Sungchul Bae

  2. Department of Civil Engineering and Architecture, Muroran Institute of Technology, Hokkaido, 0508585, Japan

    Jihoon Kim

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Suh, H., Im, S., Kim, J. et al. Instant mechanical recovery of heat-damaged nanosilica-incorporated cement composites under various rehydrations procedures. Mater Struct 55, 5 (2022). https://doi.org/10.1617/s11527-021-01847-y

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