Effect of Inorganic SiO₂ Nanofibers in High Strength Cementitious Composites

¹ Brno University of Technology, Faculty of Civil Engineering, Veveri 95, 602 00 Brno, Czech Republic
² Universität Innsbruck, Institut für Konstruktion und Materialwissenschaften, Arbeitsbereich Materialtechnologie, Technikerstraße 13, A-6020 Innsbruck, Austria

Abstract

The paper deals with the verification of the effect of the addition of inorganic SiO2 nanofibers to cement composites. In the first stage, a stable suspension of SiO₂ nanofibers was prepared in an aqueous medium. It is important to distribute nanofibers so that the nanofibers do not appear in the form of clumps and at the same time do not get damaged during the dispersion process. The ultrasonification process was used for dispersion. The dispersed suspension of SiO₂ nanofibers and water was dosed together with the superplasticizing admixtures into the dry components of the cement composite and the components were homogenized. The properties of the cement composite with SiO₂ nanofibers have been tested – compressive strength, flexural strength, density. Composites with the addition of SiO₂ nanofibers at a dose of 0.008 % by weight of cement exhibited an increased compressive strength of up to 33 % and a 19 % greater flexural strength at doses of 0.016 and 0.032 % of cement weight than the reference sample without nanofibers. The presence of SiO2 nanofibers in the composite was monitored by scanning electron microscopy (SEM).