Red mud as a pigment in production of concrete elements

Abstract

Red mud - a waste product in alumina production, with its physical and chemical properties can be used as a pigment in the manufacture of concrete elements and façade colors. However, the consumption of red comparing to conventional inorganic oxide pigments is at least three times higher for achieving the same intensity of color. Since the rise in quatity of pigment in the concrete can lead to an increase in small fractions and the need for water in the concrete mixture, and deterioration concrete's technical properties (decrease of hardness, frost resistance, etc...), it is necessary to eliminate that negative effect with introduction of certain supplements in red bud. This can be achieved by adding a certain amount of hydrochloric acid for neutralization of alkaline mud solution and the creation of CaCl2 in the reaction with lime contained in it, which serves as accelerator of boning and hardening of concrete mixtures. Concrete materials colored with red mud treated in such manner, in addition to increased strength also have higher color intensity. Obtained concrete elements colored with the same quantity of red mud, without dosing and with dosing of various quantities of HCl will be photographed, and the photographs will be presented in the paper. The aim of this paper/work is a synthesis of cheap red pigment with satisfactory performance.