Subgrade resilient modulus variation in low-volume roads design in north-eastern Brazil

The current asphalt pavement design method instituted in Brazil, MeDiNa, requires tests to determine the parameters of resilient modulus and permanent deformation of the granular layers. As these tests have a long execution time and high cost, this study analysed the variation of the resilient modulus (using composite model tested and linear predicted values) of low-volume road subgrade and the impact on the pavement design. This study simulated four different subgrades considering the soils of the metropolitan region of Fortaleza, Ceara, north-eastern Brazil and three predefined pavement structures. Total and subgrade rutting provided by the MeDiNa software were used as evaluation parameters. The simulation results allowed the authors to verify that the calculated rutting values are very close despite the resilient modulus adopted. In conclusion, road designers can consider any predicted linear value of the resilient modulus or composite models in the design of these highways, even with forecast errors greater than 20%. The study also proposes a low-volume road design catalogue considering the subgrades analysed.