Influence of Compaction Moisture on the Mechanical Behavior of Soil-Gravel Mixtures

The accumulation of permanent deformation is a structural defect that typically occurs in the form of Rutting (ATR) and can compromise the comfort and safety of users when traveling on roads. This article addresses the concern about permanent deformation in soil-aggregate mixtures in road pavement projects, especially after the transition from empirical design methods to mechanistic-empirical methods guided by pavement mechanics. Through a series of tests conducted using the repeated load triaxial equipment, with different proportions of aggregate/fine materials and tropical soil, it was observed that when compacting samples of soil-aggregate mixtures at their corresponding optimum moisture content, the fine matrix, in some cases, exceeds its optimum moisture content. As a result, the values of permanent deformation become excessively high, which can render the use of these mixtures in pavement layers unfeasible. However, the study also indicates that soil-aggregate mixtures with higher proportions of aggregate/fine materials and certain types of soils showed satisfactory results. This suggests the need to revise the definition of the optimum compaction moisture content for the design. This revision is crucial to ensure the proper performance of these mixtures in pavement layers.