Influência dos métodos de dispersão e surfactantes na estabilidade de suspensões aquosas de Nanotubos de Carbono, óxido de Grafeno e Grafite para aplicação em compósitos de cimento portland

Abstract

The incorporation of nanoparticles into cementitious compounds is one of the most intensively explored areas of scientific research today. However, the direct addition of these nanoparticles to Portland cement paste often results in agglomerates, compromising the uniform distribution and effectiveness of the additions. Traditional mixing methods can lead to inadequate dispersion, generating areas of fragility in the cement matrix and contradicting the objective of improving the performance of the composite. This research sought to investigate the dispersion process of carbon nanotubes, graphene oxide and graphite in cementitious composites, focusing on the evaluation of aqueous suspensions with the addition of surfactants and the analysis of the effects of ultrasound and mechanical agitation. The dispersions were analyzed beforehand, and only after identifying the most suitable configuration were they applied to the cement pastes. Dispersion methods such as ultrasound and mechanical agitation were used in conjunction with analysis by UV-vis spectroscopy, zeta potential and optical microscopy to assess the stability of the suspensions and the size of the particles. The ideal surfactant concentrations were defined as 10% w/w for graphite, 20% for OG and 30% for NTC, parameters that can vary according to the application, due to the direct impact on the workability, resistance and absorption of the pastes. The results showed that the dispersion techniques applied significantly reduced particle size, although some agglomerates still persisted, especially for graphite. The application of the dispersions to cement pastes showed promising results, with an increase in mechanical strength and a reduction in capillarity, indicating the viability of nanoparticles as additions for the development of more efficient cement composites.