Geotechnical Behavior of Soil-electric Arc Furnace Slag Mixtures Under Carbonation

Abstract

Although the treatment of soils with lime-based materials is used in many earthworks projects, there are only a few studies that deal with the quantification of their carbonation.The objective of this work was to investigate the influence of carbonation in mixtures between two samples of tropical soils and Electric Arc Furnace Slag (EAFS) in terms of Unconfined Compressive Strength (UCS), mini-CBR index, mini-CBR expansion, and Resilient Modulus (RM) properties. Four types of curing were used: (1) conventional sealed curing in a humid chamber; (2) conventional sealed curing in a humid chamber followed by unsealed curing with exposure to air; (3) conventional sealed curing in a humid chamber followed by unsealed curing in an accelerated carbonation chamber. In addition, tests were performed to determine the carbonation depth by spraying phenolphthalein, pH, scanning electron microscopy (SEM), and X-ray diffraction (XRD). It was found that the results of the soil-EAFS were better than those of the soil samples not stabilized for all the curing processes analyzed. In the curing processes (1), the formation of calcium aluminum silicate hydrate structures (CASH) was found to improve the mechanical behavior of soil-EAFS mixtures. The formation of calcium carbonate (CaCO₃) was observed in curing processes (2) and (3), which significantly improved the mechanical properties. Thus, the carbonation process increases the strength and stiffness of the soil-EAFS mixtures, which guarantees the durability of these mixtures over the years.