abstract
Red mud (RM) is a solid waste derived from processing bauxite ore to produce alumina and is considered a hazardous waste due to its high pH. This paper describes the use of untreated mud and after calcination at distinct temperatures (450, 650, and 1000 degrees C) to attempt to improve its reactivity in cement mortars. In the formulations, portland cement was replaced with up to 30 wt% red mud, and the addition of the red mud changed the hydration process, setting time, and workability. The temperature of hydration increased as more RM was added, particularly when calcined in the interval of 450-650 degrees C. In these conditions, the hydration process was accelerated, and the workability decreased. These findings indicate that the presence of red mud significantly altered important properties of portland cement.
keywords
BLAST-FURNACE SLAG; RICE HUSK ASH; MINERAL ADMIXTURES; BAUXITE; CLAY
subject category
Engineering
authors
Ribeiro, DV; Silva, AS; Labrincha, JA; Morelli, MR
our authors
João António Labrincha Baptista
Full professoracknowledgements
The authors wish to thank the Sao Paulo Research Foundation (FAPESP), The Postgraduate Program in Materials Science and Engineering at the Federal University of Sao Carlos (PPGCEM/UFS-Car), and the Ceramics and Glass Engineering Department, University of Aveiro & CICECO (UA/DECV) for their support of this research. Also, the authors thank Dr. Luciano Senff for his help with the calorimetric and rheological measurements.