Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification
1
Department of Civil and Environmental Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea
2
Construction Technology Research Center, Korea Conformity Laboratories (KCL), 199 Gasan digital 1-ro, Geumcheon-gu, Seoul 08503, Korea
3
Institute of Construction and Environmental Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea
*
Author to whom correspondence should be addressed.
Materials 2020, 13(13), 2950; https://doi.org/10.3390/ma13132950
Received: 25 May 2020
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Revised: 28 June 2020
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Accepted: 30 June 2020
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Published: 1 July 2020
(This article belongs to the Special Issue New Findings of Portland Cementitious Materials)
This study investigated the heat-induced acceleration of cement hydration and pozzolanic reaction focusing on mechanical performance and structural modification at the meso- and micro-scale. The pozzolanic reaction was implemented by substituting 20 wt.% of cement with silica fume, considered the typical dosage of silica fume in ultra-high performance concrete. By actively consuming a limited amount of water and outer-formed portlandite on the unreacted cement grains, it was confirmed that high-temperature curing greatly enhances the pozzolanic reaction when compared with cement hydration under the same environment. The rate of strength development from the dual reactions of cement hydration and pozzolanic reaction was increased. After the high-temperature curing, further strength development was negligible because of the limited space availability and preconsumption of water under a low water-to-cement environment. Since the pozzolanic reaction does not directly require the anhydrous cement, the reaction can be more easily accelerated under restrained conditions because it does not heavily rely on the diffusion of the limited amount of water. Therefore, it significantly increases the mean chain length of the C–S–H, the size of C–S–H globules with a higher surface fractal dimension. This finding will be helpful in understanding the complicated hydration mechanism of high-strength concrete or ultra-high performance concrete, which has a very low water-to-cement ratio.
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Keywords:
cement hydration; pozzolanic reaction; small-angle X-ray scattering; nuclear magnetic resonance
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MDPI and ACS Style
Lee, N.; Jeong, Y.; Kang, H.; Moon, J. Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification. Materials 2020, 13, 2950. https://doi.org/10.3390/ma13132950
AMA Style
Lee N, Jeong Y, Kang H, Moon J. Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification. Materials. 2020; 13(13):2950. https://doi.org/10.3390/ma13132950
Chicago/Turabian StyleLee, Nankyoung, Yeonung Jeong, Hyunuk Kang, and Juhyuk Moon. 2020. "Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification" Materials 13, no. 13: 2950. https://doi.org/10.3390/ma13132950
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