A permanent deformation predictive model for fine tropical soils considering the effects of the compaction moisture content on material selection

Abstract The evaluation of the mechanical behavior of soils should be considered as an important step for material selection and pavement design. The analyses of the elastic and plastic behaviors of the pavement unbound materials have generally been based on resilient modulus (RM) and permanent deformation (PD) tests, respectively. Such mechanical characteristics are significantly affected by factors including gradation, traffic speed, loading history, and moisture content. However, special attention should be given to the moisture content, given that the use of inadequate water content during compaction can lead to premature failure of the pavement system. This paper investigates the effects of the compaction moisture content on the plastic behavior of fine soils by means of PD. Based on the analysis of two existing models that take this key factor into account, a predictive model tailored for fine tropical soils is proposed. Four soils of different classifications were tested with three distinct compaction moisture contents (below the optimum, at the optimum moisture, and above the optimum moisture contents) to analyze interaction effects for a PD predictive model. Two additional fine soils are used to validate the model. A statistical analysis considering the six fine soils indicates that the proposed PD model can efficiently predict the effects of the compaction moisture content on the long-term resistance to PD of the fine soils and that the suggested procedure can be potentially used as a tool for material selection.