Aproveitamento de rejeitos das indústrias de cal na composição de camadas granulares de pavimentos e aterros rodoviários

Abstract

The objective of the studies in this work is the use of lime industry waste, aiming at the composition of granular layers for the construction of road sidewalks and special embankments. These residues form piles of accumulations in the yards of limestone calcination industries (whitewash). The identification of a useful destination for these residues would provide another economic gain for the lime producers, as well as a significant environmental benefit in the lime producing areas and their surroundings. Three distinct lime producing areas in the state of Ceará, located in the municipalities of Coreaú/Sobral, Forquilha and Quixeré, were selected. To evaluate the effect of lime tailings on soil stabilization, geotechnical tests were performed on samples including a mixture of soil and tailings. The studies proceeded with the location of the research areas, through georeferencing, as well as the collection of soil and tailings samples, used in the compositions of the soil-reject mixtures. Subsequently, for the geotechnical characterization of the soil and samples of the soil-reject mixtures, the Granulometric Analysis tests were performed, with determination of the physical indexes of Compaction and Moisture, CBR, Expansion and HRB Classification. In all, 21 samples were tested, 7 corresponding to each of the three study areas and one soil analysis common to all. The research results indicate that the samples meet the geotechnical specifications, defined by the CBR and the Expansion Index, with the addition of tailings to the soil in the proportions of 0%, 20%, 30%, 40%, 50%, 60%, 70% and 80%. The research pointed out advantages in the use of the tailings, revealing to be a soil stabilization agent, reflected by the reduction of the expansion to acceptable levels. For the chemical characterization of the limestones from each area, four samples were analyzed, through X-Ray Florescence. These analyses showed that Coreaú/Sobral and Quixeré are calcitic limestones; Forquilha is magnesian limestone.