Avaliação da sustentabilidade de sistemas de vedação estrutural com e sem coprodutos da extração de pedra ametista

Abstract

The extraction of precious gemstones that for more than 30 years has transformed Ametista do Sul region, in the northwest of the state of Rio Grande do Sul, into the world hub producer of amethyst stone, has an environmental liability in the mining residues. The miner’s cooperative, COOGAMAI, has more than 220 gemstones mines registered in activities that generate more than 25 thousand tons of waste per month. A non-significant portion of this material is commercialized, falling under the concept of a co-product, while most demand suitable locations for disposal. Given this scenario, the objective of this paper was centered on verifying the economic and environmental potential of replacing aggregates such as sand and gravel by the co-product in comparisons of nine compositions of 1 m² external structural walls with concrete molded on site, structural masonry in concrete bricks and structural masonry in ceramic bricks, facing the methodologies of LCA (Life Cycle Assessment) and LCC (Life Cycle Cost), from the cradle to the grave. The environmental results of LCA indicate that the structural masonry walls, both in concrete an ceramic bricks, are more environmentally efficient than the ones with concrete molded on site. The co-product of the extraction of amethyst stone presents significant contributions in the reduction of environmental impacts, when total substitutions occur, as in the scenario P06 with reductions of 16% in global warming or 41% for the formation of particulate material. The wall with concrete molded on site P09, with 100% of amethyst co-product, also showed a 17% reduction in ozone depletion or 10% in fossil depletion. The economic compositions of LCC, indicate that concrete walls molded on site are 35% less expensive, on average, when compared to structural masonry walls. The global analysis of economic and environmental sustainability, allowed to identify the contribution of the co-product of amethyst stone, with reductions close to 5% between scenarios of the same constructive typology and a reduction of 20% in the P09 scenario, listed as the best performance, against the walls of structural masonry. Above all, the use of a coproduct from the extraction of amethyst stone presents conditions for replacing natural aggregates, even if in partial proportions. With this, it becomes an alternative source of income for the local chain, which, within a circular economy, at the same time, guarantees an efficient solution for the correct destination of waste from the extraction of precious stones.