Tropical soils for highway construction: Peculiarities and considerations

Tropical soils have properties and behavior that are different from sedimentary soils due to the diversity of environments of formation. The focus of this paper is to identify peculiarities that depend on the formation conditions of the soils and the location of highways. It discusses the use of tropical soils in highway construction, making use of physical and soil structure models to facilitate a better understanding of soil properties and behavior. The paper presents aspects ranging from deposit exploitation (borrow areas) for highway construction purposes to issues related to behavior of these soils. To do this, data from several research sources on Brazilian soils were used, noting that climate, geological, geomorphological, and biological peculiarities cause different results not only from one country or continent to another but also between micro regions and even over weathering profiles close to one another. It was found that chemical, mineralogical, physical characteristics change and soil structure depending on the type of tropical soil studied and these characteristics have a direct influence on their behavior. Consequently, for pavement design, non-conventional tests should be done to define field procedures to be used during construction. In particular, some questions related to the soil water characteristic curves and compaction of fine tropical soils are highlighted.