resumo
Red mud, which is a solid waste produced in the alumina production process, is classified as dangerous due to its high pH. In this work, the concentration of chlorides was monitored by measuring the conductivity of the anolyte, which initially was distilled water. The steady and nonsteady-state chloride diffusion coefficients were estimated from the "time lag" and "equivalent time" between diffusion and migration experiments. The capillary water absorption, apparent porosity and pore size distribution of concretes were also analyzed. The addition of red mud apparently ensured lower chloride diffusion in the tested mixtures due to its superfine particle-size distribution and its "filler" effect. Red mud lengthened the service life of the concrete to 35 years (double that of the reference concrete). This finding is very positive since it indicates a delay in the onset of the rebar corrosion process caused by the migration of chloride ions.
palavras-chave
COEFFICIENTS
categoria
Materials Science
autores
Ribeiro, DV; Labrincha, JA; Morelli, MR
nossos autores
João António Labrincha Baptista
Professor Catedráticoagradecimentos
The authors wish to thank the CNPq - National Counsel of Technological and Scientific Development (Brazil), PPGCEM/UFSCar - The Postgraduate Program in Materials Science and Engineering at the Federal University of Sao Carlos (Brazil) and the UA/DECV - Ceramics and Glass Engineering Dept., University of Aveiro & CICECO (Portugal) - Project FCT-PTDC/CTM/65243/ 2006, for their support of this research. *This project did not have the financial support of Alcoa Brazil.