Abstract—Under repeated traffic loading, knowledge and understanding of cumulative permanent deformation and failure mechanisms for subgrade soils (fine-grained soils) are crucial for the proper design and maintenance planning of pavement structures. In other words, considering the great contribution of subgrade soils to the overall performance of pavement structures, it is crucial to provide the best prediction of permanent deformation behavior. This paper presents a new predictive equation for the permanent deformation of fine-grained soils (A-4a and A-6a soils) utilizing the dummy-variable multiple linear regression technique. The permanent deformation (PD) results revealed that A-4a at OMC exhibited the least plastic deformation versus the highest plastic deformation assigned to A-6a compacted at 2% wet of OMC. The results obtained could be used to help engineers in characterizing fine-grained materials. As per the statistical analysis carried out in this study, the dummy regression for permanent deformation did not greatly improve the prediction power of the model.  
 
Index Terms—pavements, fine-grained soils, permanent deformation, dummy regression