STUDY OF RED MUD AS A FILLER IN CEMENT MATRIX

Abstract

Red mud is a residue from the processing of bauxite for the production of alumina by the Bayer process. It consists of insoluble solids (oxides) in caustic soda solution. The reddish color is the result of the high amount of iron present in this residue. According to some authors, the world production of red mud turns around 90 million tons every year. The inappropriate storage and discard of this material creates risks to the environment and society. Thus, it is important studies for the reuse of this residue in other sectors of the economy. As the civil construction is a Brazilian economy sector that demands large consumption of cementitious materials, the present study sought to analyze the viability of the use of red mud in a cement matrix. The material was used as a filler to replace the cement in the proportions of 5%, 10% and 15% in concrete. It was carried out studies to evaluate the physical and mechanical properties of the concrete produced including simple compression test, diametral compression and capillary absorption. It was also carried out tests of durability to identify the possible presence of expansibility and alkali-aggregate reaction resulted from the use of the red mud in cementitious mortar matrix The results showed that the use of red mud as partial replacement of the cement promotes the increase of the mechanical resistance, but its use can generate expansive reactions.