Funcionalização de argamassa com deposição de titânia (Ti02) produzida por rota sol-gel

Abstract

The costs with development and maintenance of buildings create considerable impacts to a countrys economy. Therefore, their durability is greatly important to favor a healthy economy. The buildings facades can be considered as the elements with the most of contact with the external environment. Thus, by understanding that the degradation begins from the outside to the inside, the functionalization of construction materials used on facades can be a viable alternative to prevent this process. This functionalization can be done with titanium dioxide due to its particular properties. The photocatalytic property of the TiO2 is capable to promote the degradation of the air pollutants. And, associated to the superhydrophilicity, it could activate the elf-cleaning property. The sol-gelprocess for nano and micro titania fabrication appears as a possible methodology to be used for coatings. Such route presents a low cost, high pureness, and homogeneous product. In this context, the current research has the aim to make mortars functionalized with thin films of titanium dioxide produced by sol-gel technology in order to produce surfaces with self-cleaning property. Samples were produced with three types of coatings deposited by dip-coating. The first one with only a layer of titanium dioxide, the second with two layers of titanium dioxide, andthe last one with a silicium dioxide layer coated then by an external titanium dioxide layer. All these coatings were made using sol-gel solutions. For comparison, samples were also made with the deposition of crystalline sol-gel powder dispersed in alcohol and with the incorporation of crystalline sol-gel power of titanium dioxide into the mortar structure, in agreement with the comun methods used in this kind of study. The samples were haracterized by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, compressive strength, increase and loss of mass, and exposure to climatic conditions. The obtained results infer that the coating technique was effective, however a huge number of cracks is observed on the deposited films. It was not to identify the crystaline phases present in the materials by x-ray diffraction, and the mass loss observed after the heat treatment in the mortar samples slightly damages its compressive strenght. Finally, variations related to degradation or reduction of dirtiness on the surface of the samples exposed to external weather conditions were not observed for any sample. However, the amount of TiO2 present on the surface, and potentially able to promote the self-cleaning property, was higher in samples coated with the sol-gel technology in comparison with the methods classically used in the construction area.