Effects of the pozzolanic reactivity of nanoSiO2 on cement-based materials |
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| Affiliation: | 1. School of Materials Science and Engineering, University of Jinan, Jinan, Shandong 250022, China;2. Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, Jinan, Shandong 250022, China;3. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China;4. Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA;1. Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga, Spain;2. Servicios Centrales de Investigación, Universidad de Málaga, 29071 Málaga, Spain;3. ALBA-CELLS Synchrotron, Carretera BP 1413, Km. 3.3, 08290 Cerdanyola, Barcelona, Spain;1. Department of Civil Engineering, Federal University of Santa Catarina – UFSC, Rua João Pio Duarte Silva 250, Córrego Grande, CEP 88040-900 Florianópolis, Santa Catarina, Brazil;2. Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, USA;1. Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, Jinan, Shandong, 250022, China;2. School of Materials Science & Engineering, University of Jinan, Jinan, Shandong, 250022, China;3. Department of Civil and Environmental Engineering, Northwestern University, Evanston, 60208, USA;1. College of Civil Engineering, Hunan University, Changsha, Hunan 410082, China;2. Department of Civil & Environmental Engineering, University of Louisville, KY 40292, USA;3. Center for Advanced Cement-Based Materials, Northwestern University, IL 60208, USA |
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| Abstract: | The aim of this work is to understand the characteristics of the pozzolanic reactivity of nanoSiO2 from studies of its pozzolanic reaction kinetics, morphology and structure of the hydrates and the influences of these features on the properties of cement-based materials, so as to explore a more targeted way of using nanoSiO2 in cement or concrete. It revealed that the pozzolanic reaction of nanoSiO2 is of the first-order and the apparent reaction rate constant of nanoSiO2-4 nm is about one order of magnitude bigger than that of silica fume, but the specific reaction rate constant is about one half to that of silica fume. A compacter gel structure and poorer crystallinity of the hydrates of nanoSiO2 to those of silica fume are found, as well. The rate of hydration of cement at very early ages is enhanced by nanoSiO2, but the rate slows down with aging due to the compact gel structure. To make the use of the high pozzolanic reactivity and ultrafine particle size of nanoSiO2, as well as its resulting compact gel structure, colloidal nanoSiO2 was applied onto the hardened cement mortar by brushing technique and a less permeable surface was resulted, which shows the potential of using nanoSiO2 as a surface treatment material for cement-based materials. |
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| Keywords: | Pozzolanic reactivity Surface-treatment |
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