Desenvolvimento de corpos cerâmico utilizando ativação alcalina no resíduo da cerâmica vermelha.

Abstract

The alkaline activation is based on the use of reactive precursors containing silica and alumina in its constitution, which after being exposed to alkaline environments and contact with electrostatic compensation cations, such as Na+ and K+, they develop a cementitious material. The residue of red ceramic, being composed by silicon and aluminum, has the potential to be used in the development of new activated alkaline materials. Thus, this research aimed to recycle waste from the production of tiles and ceramic blocks for production of ceramic specimens by alkaline activation process. Initially characterization of the precursor material by chemical analysis, XRD and thermal analysis (TG/DTA) was performed. Subsequently, the optimization of the particle size and the amount of water used in the formulations was done. Next it was examined the influence of Si/activator ratio in mechanical performance of mixtures that contain red ceramic residue, sodium hydroxide, potassium hydroxide and sodium silicate as alkaline activators. The optimal condition of curing was determinate using an experimental planning 22 type star with center point, having as variables the temperature and concentration of alkaline activator and answer the mechanical strenght, and evaluated the durability and ageing by simulating driving rain, natural ageing, exposure to acidic media (hydrochloric and sulfuric acid) and salt spray . For this, cylindrical specimens were fabricated in the dimensions of 2.5 x 5.0 cm (diameter x height), with the proportions of Si:Al:Activator 3:1:1 and 2:1:1 . It was observed that a great time is required for the occurrence of geopolymeric reactions improving the mechanical properties of the products obtained. However, when products are subjected to more aggressive conditions of exposure, mechanical properties decrease due to leaching.