Avaliação da lixiviação de cromo em monólito de concreto por imersão e irrigação

Abstract

Nowadays the search for alternatives that minimize the consumption of raw materials and energy and thus reduce costs requires studies focused on environmental issues. Therefore, increasingly, scientific research and technology are being conducted to find ways of waste back to the production cycle and thus reduce their generation and disposal in landfills. With the industrialization and the variety of wastes containing heavy metals such as chromium (Cr), present in soil or industrial wastewater, these are stabilized by immobilization of its contents, using a solidification by solidification (S/S) technique in concrete matrix. Nevertheless, the way how the waste is treated can cause negative environmental impacts due to the waste type, technology used and its use as new material from the combined use of the residue with the raw material and even with other waste. It is observed that the existing Brazilian standards today to analyze waste are being used to evaluate the products from the S/S which usually simulate final disposal situations in landfill, only focusing on waste, not considering the actual behavior of these products, over its use. In this context, the aim of this study is to evaluate the Unisinos/Inovatec method for obtaining leached extract stabilized and solidified products (S/S) analyzing the Cr in cement concrete matrix, , overlooking to employment in the environmental assessment of materials and construction components. For this, specimens were prepared with and without addition of 2% chromium oxide (Cr2O3) and were subjected to leaching tests by immersion and irrigation. The concrete properties were evaluated through the Slump test, compressive strength and porosimetry. The chemical characterization of cement paste samples was made through analysis of XRD, SEM, ICP-OES and pH. The deionized water used in the acid leaching solution, and leaching extracts collected in the immersion and irrigation tests were analyzed by ICP-OES. From the results obtained in the two leaching tests, by immersion and irrigation, it was found that 99.99% of Cr was encapsulated. The proposed Unisinos/Inovatec method for obtaining leached extract in concrete with Cr showed the same trend of behavior observed in a study with red ceramic. Among others, this fact can be considered as a positive aspect to the adoption of the proposed method, in view of the environmental assessment of the incorporation of waste in construction components.