Avaliação do uso de resíduo de mármore Bege Bahia como substituto do calcário na produção de clínquer e como material carbonático para cimento portland

Abstract

The production process of ornamental stones generates as a by-product a significant amount of waste that is deposited in the environment, creating a great environmental liability. That is the case of the waste of Bege Bahia marble, found in the region of Ourolândia, Bahia. Civil construction is an industry that generates waste and extracts natural resources to obtain its raw material. One example is the production of cement, whose main raw material is limestone, which has properties similar to Bege Bahia marble. Despite the existence of research on the use of marble waste in cement production, none of them used Bege Bahia marble. They also did not consider the simultaneous replacement of limestone in the production of clinker and in the production of cement itself, as a filler. Therefore, the goal of this research was to develop cement using Bege Bahia marble powder (BBMP). An experimental program was carried out, starting with the characterization of the BBMP and the materials used, followed by the development of cement formulations. In the first stage of the experimental program, the raw materials, limestone, clay, copper slag, calcium sulfate and BBMP had their chemical, physical, mineralogical, thermal, and environmental properties determined. In the second stage, it was defined the amount of BBMP, as a limestone replacement, into clinker production. Clinkers produced had 37%, 49%, 77% or 80% of the mass of BBMP. After mineralogical analyses, clinkers with 77% and 80% of BBMP were chosen for use in the next stage as they presented the quantities of minerals closest to the industrial commercial clinker. In the last stage, the properties of cements produced with the developed clinkers, 4.47% of calcium sulfate and 25% of carbonate material (limestone filler or BBMP) were analyzed. The results were compared to the reference cement (industrial clinker and the same quantities of calcium sulfate and carbonate material). The results showed that the BBMP has physical, chemical, thermal and mineralogical characteristics very similar to the limestone it replaced. BBMP caused no significant changes in the hydration or in the mechanical performance of the cement, when compared with the reference. Therefore, it is believed that the BBMP is a proper substitute for limestone, which contributes to the decrease in the extraction of natural resources and to definition of a destination for the waste of the Bege Bahia marble industry.