No abstract

The foundry industry generates large amounts of residual byproducts, such as waste foundry sand (WFS). This high generation has motivated studies concerning the disposition of WFS, which in turn can be used for road subbases. Nevertheless, paving applications are still limited, especially regarding the behavior of WFS when added to a mixture of crushed materials. Hence, the objective of this study was to evaluate WFS reuse in mixtures with crushed materials, applied as granular layers of granulometric stabilized pavements. The crushed materials and WFS were characterized by size distribution, physical aspects, and different mixtures, and later submitted to mechanical testing. Initial tests were utilized to define mixtures (crushed material + WFS) that fulfilled the technical requirements for road subbases. California bearing ratio and resilient modulus tests indicated that WFS additions up to 12% for “A” grading improved the bearing capacity of the mixture; while in “E” grading, WFS additions up to 38% resulted in no expressive improvement in bearing characteristics. Thus, for both gradings, a structure with high density, strength, and low susceptibility to deformations can be used for road subbase construction without technical issues. Finally, the highest WFS content (38%) mixture was environmentally classified as a Class II A non-inert waste, indicating its environmental viability for road applications.

A exposição de geomateriais à lixiviados ácidos pode provocar alterações em sua microestrutura em função da dissolução de metais, dessorção de espécies químicas e dissolução parcial de minerais. Modificações nas propriedades dos geomateriais expostos a condições de extrema acidez ainda necessitam de maiores investigações. Sendo assim, este trabalho avaliou a microestrutura de amostras de caulim submetidas à contaminação por ácido sulfúrico nas concentrações de 0,00 e 1,00 mol/L, em ensaios de batelada e de consolidação. As amostras ensaiadas foram caracterizadas por espectrometria de fluorescência de raios X, difração de raios X e microscopia eletrônica de varredura. O contato com a solução ácida de 1,00 mol/L resultou na solubilização de alguns minerais constituintes do caulim, com perda de albita, bem como a formação de mineral sulfatado, corroborando o aumento do teor de óxido de enxofre. A morfologia das partículas do caulim não sofreu alterações decorrentes da exposição ao ácido sulfúrico.