The microstructure and sulfate resistance mechanism of high-performance concrete containing CNI |
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| Affiliation: | 1. Catalytic Processes and Materials, MESA+ Institute for Nanotechnology, University of Twente, Enschede 7500AE, The Netherlands;2. Aalto University, School of Chemical Technology, Department of Biotechnology and Chemical Technology, P.O. Box 16100, 00076 Aalto, Finland;1. Chemistry Department, Faculty of Science, Benha University, Benha, Egypt;2. Chemistry Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), P.O Box 90950, Riyadh 11623, Saudi Arabia;1. Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education and Key Lab of Disaster Smart Prevention and Mitigation for Civil Engineering of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin 150090, China;2. School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China;1. Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA;2. Center for Advanced Turbomachinery and Energy Research, University of Central Florida, Orlando, FL 32816, USA;3. Department of Physics, University of Central Florida, Orlando, FL 32816, USA;1. School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulju-gun, Ulsan 44919, Republic of Korea;2. Construction Materials Center, Construction Division, Korea Conformity Laboratories, 73, Yangcheong 3-gil, Cheongwon-gu, Chungbuk 28115, Republic of Korea |
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| Abstract: | It is found from previous studies that the incorporation of calcium nitrite inhibitor (CNI) together with mineral admixtures could weaken the resistance of mixtures to sulfate attack. To better understand the mechanism of this phenomenon, the influence of CNI on the microstructure of cement-based materials is studied by means of quantitative X-ray diffraction, mercury intrusion porosimetry, and scanning electronic microscopy technique. The test results demonstrate that the incorporation of CNI accelerates the formation of calcium hydroxide and ettringite crystals, and weakens the pore refinement effect caused by the secondary hydration reaction of fly ash and microsilica. At the age up to one year, the relative crystal quantity in mixture containing CNI is always higher than that in control mixture without CNI. The reasons for the degradation in sulfate resistance of mixtures may be attributed to the increase of the calcium hydroxide and ettringite crystals formed, the increase of micropore size and the degradation of secondary hydration reaction. Based on the experimental results, conclusion can be drawn that NCI should be used cautiously in practical engineering when high resistance to sulfate attack is required. |
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