Applications, Properties and Design of High Modulus Bituminous Mixtures

High modulus bituminous mixtures (HMBM) have been used for almost two decades in several countries. This paper presents an overview of use of this kind of bituminous material, as well as a summary of its typical compositions and mechanical properties. The rehabilitation of a structural layer on the EN14 (Portuguese national highway 14) using HMBM has been adopted as a case study. The project workplan involved the laboratory design of the mixture by undertaking performance tests to observe the effectiveness of the mixture. Prismatic specimens were extracted from constructed trial sections and similar specimens have been produced in the laboratory. Repetitive four-point bending tests were performed on both specimens for several temperatures and loading conditions. This made it possible to determine their stiffness modulus, phase angle and fatigue resistance. In addition, cores and slabs taken from trial sections have been used to characterise the permanent deformation behaviour of HMBM in laboratory. Wheel-tracking and repetitive loading axial tests (RLAT) were adopted for that purpose. The findings have led to some recommendations for the design of HMBM.