Reciclagem de resíduos de serragem do granito e do beneficiamento do caulim utilizando ativação alcalina.

Abstract

The construction industry is responsible for strong impacts on the environment. An alternative to attenuate this problem would be the incorporation of alternative materials to replace the ones conventionally used, for example, the Portland cement. This study aims the development of geopolymeric systems for the composition of blocks, using industrial waste from the kaolin and granite processing industry. Initially the waste was characterized through X-ray fluorescence, particle size by laser, X-ray diffraction and thermal analysis. The proper amount of water for the formulation of the compositions was determined using a simplex centroid experimental design. Then, the influence of the curing conditions were analyzed using cures in an oven at temperatures of 60°C and 100°C and room temperature, through an experimental design type simplex centroid mixture design. The materials were submitted to mechanical characterization, with determination of the compressive strength, and microstructural characterization through X-ray fluorescence, X-ray diffraction, thermal analysis and laser porosimetry. The last stage involved the analysis of durability and aging behavior of the specimens produced, using environmental and saline mist exposure, wetting and drying tests and immersion in HCl and H2SO4. The materials produced presented mechanical compression strength of up to 8MPa. The specimens that presented best mechanical behavior were the ones with high amounts of fine kaolin waste, despite the higher amount of water required in its production. It was verified that the type of activator has influence on the mechanical behavior of the produced materials. Regarding the durability of the materials it was verified that the materials activated with NaOH exposed to the environment presented an increase of 3% in the mechanical strength at 60 days of exposure, while with KOH remained stable. When submitted to saline mist the increase was of 7% for the NaOH and 1% for the KOH. In the wetting and drying tests the mechanical strength for NaOH presented a decrease until the 12th cycle, increasing thereafter, while the KOH lost strength during all cycles. In the immersion in acids, the activation with NaOH presented strength loss of 25% and with KOH these values reached 50%, with both activators the materials presented high mass loss after immersion in acid, however, the values were inferior to the ones observed in specimens containing Portland cement.