The Effect of Natural SiO2 Nanoparticles on the Performance of Portland Cement Based Materials

摘要

This research reports on the performance of nano-SiO2 particles from natural hydrothermal solutions obtained by membrane ultrafiltration and,optionally,by cryochemical vacuum sublimation drying in portland cement based systems.The SiO2 rich solutions were obtained from the wells of Mutnovsky geothermal power station(Far East of Russia).The constant nano-SiO2 dosage of 0.25%(by solid material weight of cementitious materials)was used to compare the cement systems with different nanoparticles against a reference mortar and a commercially available nano-SiO2.Nanoparticles were characterized by X-Ray Diffraction(XRD),BET Surface Area,Scanning Electron Microscope(SEM)and Fourier Transform Infrared(FTIR)spectroscopy.The distribution of nano-SiO2 particles within the cement paste plays an essential role governing the overall performance of these products.Therefore,the addition of polycarboxylate ether superplasticizer and the dispersion treatment using an ultrasound processor were used to facilitate the distribution of nano-SiO2 particles in mixing water.The effect of the nano-SiO2 particles in portland cement systems was quantified by evaluating the flow,heat of hydration and compressive strength development.It was demonstrated that the use of nano-SiO2 particles can reduce the segregation and improve the strength which is essential for many applications including Self-Consolidating Concrete.