Uso de rejeito da mineração de caulim na fabricação de tijolo solo-cimento

Abstract

The materials that are produced in the mining industry generate waste that, because they do not have economic value, are stored according to specific legislation, however, they still present a potential risk of causing environmental impacts to the environment. This work aimed to use the kaolin mining tailings in the State of Pará, for the manufacture of a soil-cement brick in partial replacement of sand in the percentages 10%, 20%, 30% and 40%. The Sandy soil was chemically and mineralogically characterized and the kaolin tailings sample was subjected to chemical, mineralogical, morphological and physical characterizations for the determination of the trait for the manufacture of thebrick, according to the norm ABNT NBR 8491:2012. The results of characterization of the Sandy soil indicated SiO2 content above 97% and the mineralogical phase of the mineral quartz. Chemical analysis of the kaolin mining tailings identified the presence of SiO2 (82.96%) and Al2O3 (15.11%); being the mineralogical phase of predominant quartz, followed by kaolinite; the morphological analysis showed grains with pseudohexagonal shapes and in stacked layers and others with rounded shapes and angular, characteristic of kaolinite and quartz respectively; in the physical analysis, it obtained a plasticity index lower than 7.74% and a liquid limit below 45%, characteristic of sandy soils; the granulometric analysis carried out on the kaolin waste classified it as predominantly fine sand with a portion of silt/clay, the same test carried out on the sandy soil classified it as predominantly consisting of medium sand, with a portion of coarse sand. In the compressive strength test, only the soil-cementbricks of the mixes that contained 20%, 30% and 40% of kaolin mining tailings were in accordance with what the standard requires; in the water absorption test, only the mix containing 0% kaolin waste was rejected in the average of the values obtained and the mixes containing 20% and 30% showed the best results; the mix containing 30% kaolin waste was the most suitable for the manufacture of soil-cement bricks, as it presented the best results and used more waste than the 20% mix.