Québec roads are subjected to seasonal ambient temperature variations and daily rapid variations of temperature. These significant temperature variations in combination with the moisture inside the pores result in the development of premature deterioration in asphalt pavement. At present, the effect of regional freeze-thaw cycles on fatigue cracking has not been considered in the Mechanistic-empirical pavement design guide method or other design methods in cold regions, whose results overestimate the pavement life. Hence, the main objective of this study was to conduct the thermomechanical tests on an asphalt mixture before and after rapid freeze-thaw cycles. Considering the differences regarding the 2S2P1D model parameters, it was found that the influence of freeze-thaw conditions on the stiffness behavior of the mix is higher when increasing the number of cycles from 150 to 300. Regarding fatigue test results, the reference mixture was more resistant to fatigue cracking than the conditioned mix after 300 freeze-thaw cycles.
1 October 2020 in Construction and Building Materials
In recent times, recycling using cold bituminous mixtures has become one of the most interesting techniques in pavement engineering from sustainability aspect. This study focuses on the clarification of the steps concerned with the cold mixture mix design to determine the initial aggregate gradation of the mixture. The study has been developed involving procedures followed in Canada and Italy. In both the cases, three different gradations, normally employed in the production of traditional bituminous mixtures, were compared. The effect conferred by the gradation type has been studied in terms of workability, compactability and mechanical properties. Results show that in both the procedures the gradation influenced the workability and the compaction behaviour of the mixtures studied. At the same time, in terms of mechanical properties, the gradation influenced the strength of the final mixture in only one of the procedures applied.