Concretes with red mud coarse aggregates

Abstract

Red mud (RM) is a mineral waste, residue of the Bayer process used to obtain alumina from bauxite. While the exploration of rolled pebble damages the environment and is much more controlled by the government, the huge RM disposal areas do not stop increasing and polluting soil, rivers and groundwater sources in Amazon. In this work, the material mixtures used to produce coarse aggregates presented up to 80% of RM, 30% of metakaolin and 30% of active silica as recycled waste. Several tests were carried out to determine the aggregates physical properties and to evaluate the mechanical performance of the concretes with the new aggregates, including hydraulic abrasion strength, and the results were compared to the reference ones, i.e. rolled pebble concretes. Additionally, the sintering process neutralizes any toxic substance as occur in some RM products like tiles and bricks, and these results have encouraged an industrial or semi-industrial production of RM aggregates for concretes.

Conceptual design and cost analysis of a large‐scale plant for converting red mud into building materials

“…The mean value of the axial compression strength of aggregates containing 80% RM and 20% fine sand was 55% higher than that of the reference concrete and 67% higher than that of the aggregate produced using 70% sand and 30% metakaolin. 29 The iron ore pelletizing process, for example, is a largescale production process that has a firing stage compatible with that of RM sintering. Isaias et al obtained coarse aggregates via pelletizing and extrusion.…”