António C. Azevedo

The environmental problems caused by sewage sludge generated by the growth of the global population and urbanization are drawing the attention of the scientific community worldwide to the need of developing sustainable solutions to use that material. This work investigated the possibilities of using sewage sludge, generated in wastewater treatment plants, as a strategy to improve and stabilize collapsible soils. Different soil–sludge mixtures, with 5%, 10%, and 15% of sludge, were analyzed. For the characterization and analysis of the soil–sludge interaction, physical, chemical, and edometric experiments were performed. The results showed that the addition of sludge to the soil causes a void index reduction, improves particle packaging, and reduces soil collapsibility to the same specific dry apparent weights, i.e., showed to be a promising method for the improvement of collapsible soils.