Efeito da cura em ambiente saturado de CO2 no desempenho físico e mecânico de telhas de fibrocimento

Abstract

The motivation of this work was based on the fact that cellulosic fibers suffer from the alkaline environment generated by the hydration products of the cement matrix, mainly calcium hydroxide. One of the ways found to reduce this alkaline environment is to induce the reaction of calcium hydroxide with carbon dioxide (accelerated carbonation), in addition to this alkalinity reduction, the product generated from this reaction, calcium carbonate, densifies and fills the pores of the cementitious matrix, giving the material less porosity and improving mechanical properties. In this work, the accelerated carbonation of fiber cement tiles and parameters that can influence the carbonation process, such as spacing, hydration and supply of carbon dioxide from natural gas combustion, were evaluated. To evaluate the carbonated tiles, physical-mechanical tests, thermogravimetry, X-ray diffraction, accelerated aging and drying shrinkage tests were carried out. The results obtained in thermogravimetry and X-ray diffraction showed that in the 48h exposure time to carbon dioxide it was possible to obtain an increase of 5.26% in the bulk density and a 28% increase in the modulus of rupture, reaching a degree of carbonation of 24.3%. The use of spacers between the fiber-cement tiles proved to be a beneficial method for optimizing the carbonation process, because when they were spaced, the tiles were more prone to the diffusion of carbon dioxide and to the advantages provided by carbonation. Through them, it was possible to obtain a reduction of 2.29% in the absorption of water and a 28% increase in the modulus of rupture, in addition to a significant increase in the degree of carbonation of 22.1%. Carbon dioxide from natural gas burning proved to be a promising source for use in the carbonation process of fiber cement tiles. In the evaluation of hydration by immersion, the results showed that immersion in water before and after the process did not lead to improvement in physical and mechanical properties. Generally speaking, accelerated carbonation improved the properties of fiber cement tiles in terms of physical and mechanical properties.