Avaliação da cor e taxa de exalação de radônio em rochas graníticas entre ciclos de envelhecimento acelerado

Abstract

In this thesis are willing data used for the assessment of the analyzes performed on three types of dimension stone (Juparana Bordeaux, Branco Nevasca and Golden Ártico), in natural state and after several cycles of accelerated aging, correlating with the gas exhalation rate radon issued by the analyzed lithologies. In the samples were conducted permeability, porosity, colorimetry, image analysis, petrographic and exhalation rate of radon, accompanied by aging tests on climate simulation chamber which simulates change situations of materials by weathering agents, accelerating wear and tear samples. The measurements were performed on samples in natural state, with 50 and 100 cycles of aging acceleration, where each cycle corresponds to variations in temperature and humidity in climatic simulation chamber, with the addition of an internal atmosphere of SO2 with 25 concentration ppm. The results obtained during the tests were related to better analysis of the changes observed on the samples and the variation rate of exhalation radon emitted. The rocks have radon concentration values above the limits suggested by relevant international agencies (200-400 Bq/m³), with average values in the natural state, in 6149, 1619 and 866 Bq/m³ for Juparana Bordeaux, Branco Nevasca and Golden Arctic, respectively. The other aging cycles (50 and 100 cycles) showed an average increase of 0.8% for Juparana Bordeaux, 6.9% for White Blizzard and -23.87% for the Golden Arctic, with 50 cycles. From 50 to 100 cycles, there was reduction of 3.43% for Juparana Bordeaux and 22.15% for Branco Nevasca and an increase of 13.82% in the Golden Ártico. The porosity results in the natural state obtained values an average of 0.696% for Juparana Bordeaux, 0.919% for Branco Nevasca and 0.830% for Golden Ártico, and after 50 cycles of accelerated aging, obtained 0.621% to Juparana Bordeaux, 0.910% for Branco Nevasca and 0.840% for Golden Ártico. The permeability of the samples showed values in the natural state, in mDarcy, of 1,49E-4 to Juparana Bordeaux, 3,41E-4 to Branco Nevasca and 1,56E--4 for the Golden Ártico, and in 100 cycles, the results were 4,92E-4 to Juparana Bordeaux, 4,72E-4 to Branco Nevasca and 4,88E-4for Golden Ártico. The image analysis and colorimetry showed that the samples visually showed minor variations in color during the accelerated aging cycles. With these results we it is considered that after accelerated aging cycles, the rocks studied showed an increase in most parameters assessed, especially in permeability, and a consequent increase in the rate of exhalation gas radon.