The effect of curing on the mechanical behavior of cement-bitumen treated materials

The re-use of pavement materials is an efficient and cost-effective solution in road rehabilitation and construction activities, especially when the availability of high-quality virgin aggregates is limited. In this context, cold recycling of bituminous pavements is becoming one the of most attractive and low environmental impact techniques. The use of cold-recycled pavement mixtures requires a careful assessment of their mechanical properties, which are influenced by both compositional and environmental factors. In particular, regardless of aggregate nature, binder type and dosage, a distinctive feature of cold recycled mixtures is the requirement for a certain curing period to develop the ultimate values of strength and stiffness. In this study, the mechanical behaviour of cement-bitumen treated materials (CBTM), containing high percentage of reclaimed asphalt (RA), was evaluated considering the influence of curing time and temperature. Two CBTM containing 1.0 and 2.5 % cement and 2.0 % of fresh bituminous binder were analyzed. Cylindrical specimens were compacted using a gyratory compactor and cured at 25 and 40 °C; moisture loss and indirect tensile strength (ITS) were measured at increasing curing times. Results showed that the curing temperature and time (curing conditions) significantly affect the moisture loss by evaporation that therefore can be considered a good estimator of the curing process. Moreover, the mechanical characterization indicated that the moisture loss and the cement content control the increase in strength properties of the investigated CBTM. Results also showed that the cement content strongly affects the moisture loss in addition to assure improved mechanical behavior.