1. Ph.D. Student, Pavement Mechanics Laboratory, Research Center for Territory, Transports and Environment, Dept. of Civil Engineering, Univ. of Coimbra, 3030-788 Coimbra, Portugal.
2. Director of the Road Pavements Laboratory, Pavement Mechanics Laboratory, Research Center for Territory, Transports and Environment, Dept. of Civil Engineering, Univ. of Coimbra, 3030-788 Coimbra, Portugal (corresponding author).
3. Assistant Professor, Dept. of Electromechanical Engineering, Univ. of Beira Interior, 6200-358 Covilhã, Portugal.