Estudo da resistência mecânica e resistência ao ataque ácido em compósitos cimentícios com incorporação de nanopartículas de sílica

Study of mechanical strength and strength to acid attack on cementitious composites with incorporation of silica nanoparticle

ABSTRACT

Research in materials science and engineering has sought alternatives to improve the properties and characteristics of cementitious composites. Therefore, the use of nanoparticles, such as silica nanoparticles, has been a promising alternative in the nanocomposite segment, providing improvements in physical, chemical and durability properties, due to the change in the material’s microstructure. International studies have shown benefits with the incorporation of small amounts of nanosilica in concrete, cement pastes and mortar, however, there are divergences regarding the content and size of nanoparticles of incorporated silica, and their respective effects on the properties of the fresh and hardened state of the cement materials. Therefore, the present study aims to analyze the influence of the addition of silica nanoparticles in cementitious composites, from the verifications of mechanical strength, water absorption and exposure in aggressive environments, through an analysis between four cementitious composites, being a reference sample, and in the others, contents of 0.5%, 0.75% and 1.0% of nanosilica will be added in relation to the cement mass. The cementitious composites were analyzed using the compressive strength test at 3, 7 and 28 days, water absorption and acid etching, all at 28 days of curing. In view of the results obtained, it was verified that the addition of nanosilica promoted a greater densification of the cementitious matrix, therefore, it improved the compressive strength, reduced the water absorption and the acid attack in relation to the reference. Finally, among the mixtures evaluated, it is concluded that the composite with the addition of 0.5% of nanosilica presented the best contributions to the research, being an increase of 15.6% for compressive strength and a reduction of 4.9% for water absorption and 0.2% and 1.4% for acid attack by Miranda method and ASTM C-267-01, respectively.

Keywords
Cement composites; Nanosilica; Mechanical resistance