Description
The purpose of this research was to study, in laboratory, the performance of three hot mix asphalt concretes: two using different crumb rubber and shale oil contents (M2: AC40 + 12% rubber + 10% shale oil and M3: AC40 + 20% rubber + 15% shale oil) and a conventional hot mix asphalt concrete (M1: AC40). The research is part of a major program comprehending the investigation on asphalt mixes using tire rubber and shale oil, as an extender agent. The asphalt concrete specimens were compacted in the optimum binder content of each mix. Mechanical properties of each Marshall compacted specimen were complementarily evaluated by the following tests: indirect tension, resilient modulus and static creep. Results of Marshall tests indicated an increase in the optimum binder content, a reduction of density and Marshall stability, and an increase in the air voids of the modified mixes. Results of indirect tension test indicated that modified mixes had a reduction of more than 50% in the resistance, in comparison with the conventional mix. Resilient modulus of M1 was about the double of mix M2 and about the triple of M3. Static creep tests indicated that mixes M1 and M3 have a good performance under 0.7 MPa tension and mix M2 under 0.4 MPa tension. Regardless the fact that both modified mixes containing crumb rubber and shale oil presented lower resistance than the conventional one, their physical characteristics are acceptable for constructing hot mix asphalt layers, on an experimental basis. The results lead to the conclusion that experimental road sections or segments may be constructed with both mixes to assess their viability in field conditions.
