The influence of different preparation methods on the aggregation status of pyrogenic nanosilicas used in concrete
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Investigation of the effects of nanosilica materials in cementitious mixtures has attracted considerable research attention due to the very high specific surfaces of these materials. However, high surface area leads to aggregation of these materials due to high surface attraction forces, which could seriously reduce their nano filler effect. In this research the dispersion of pyrogenic nanosilicas in water and parameters influencing it were investigated. The results show that serious aggregation of pyrogenic nanosilicas in water occurs. Increasing the amount of applied forces, particularly the use of ultrasonic waves, has considerable effect in breaking aggregates into smaller aggregates with maximum size up to 0.9 μm. Increasing the pH was found to be very effective in improving dispersion of nanosilicas and through combined use of high pH and applying high levels of energy such as ultrasonic method it is possible to break all the aggregates into primary aggregates with maximum size of about 0.06 μm.
KeywordsPyrogenic nanosilica Particle size distribution Aggregation Energy pH
Support from the building and housing research center (bhrc) is gratefully acknowledged. Authors also express their gratitude to Dr. Razavian and Mrs. Pozhhan for performing particle size distribution analyses.
- 1.ACI Committee 234 (2006) Guide for the use of silica fume in concrete. American Concrete InstituteGoogle Scholar
- 3.Brinkmann U, Ettlinger M, Kerner D, Schmoll R (2006) Synthetic Amorphous Silica. In: Bergna HE, Roberts WO (eds) Colloidal Silica, Fundamentals and applications. Taylor and Francis group, pp 575–588Google Scholar
- 7.Jo BW, Kim CH, Lim JH (2007) Characteristics of cement mortar with nano SiO2 particles. ACI Mater J 104:404–407Google Scholar
- 16.Porro A, Dolado JS, Campillo I, Erkizia E, Miguel Y de, Ibara YSaezde, Ayuela A (2005) Effect of nanosilica additions on cement pastes. In: Applications of nanotechnology in concrete design, Dundee, pp 87–96Google Scholar
- 18.Rahaman MN (2003) Ceramic processing and sintering, 2nd edn. Marcell Dekker, New YorkGoogle Scholar
- 19.Roberts WO (2006) Manufacturing and applications of water-borne colloidal silica. In: Bergna HE, Roberts WO (eds) Colloidal silica, fundamentals and applications. Taylor and Francis group, Boca Raton, pp 131–176Google Scholar
- 21.Wolsiefer J (2002) The measurement and analysis of silica-fume particle size distribution and de-agglomeration of different silica fume product forms. In: Proceeding of 5th international CANMET-ACI conference on durability of concrete, Barcelona, ACI SP242, pp 111–130Google Scholar