Visco-Elasto-Plastic Characterization in the Small Strain Domain of Cement Bitumen-Treated Materials Produced at Low Temperatures

In the framework of recycling techniques employed in maintenance and rehabilitation projects for the road industry, cement bitumen-treated materials (CBTMs) provide good performance as well as economic and environmental benefits. Because these materials are produced with bitumen emulsion at atmospheric temperature, the environmental factors during production are extremely important to guarantee the quality of the final product. This paper focuses on the stiffness of CBTMs produced and conditioned at low temperatures, and cured in two different conditions (sealed and unsealed). The mixtures were evaluated in terms of rheological properties using complex modulus (E*) tests performed 1 year after production. Results were modeled with an adapted version of the Di Benedetto-Neifar (DBN) model for plastic dissipation for small cycles (PDSC), accordingly called DBNPDSC. Results showed that the curing conditions, as well as the low production temperatures, significantly changed the rheological properties of the material. In fact, mixing or compacting the mixtures at 5°C compared with 25°C resulted in a loss in stiffness of around 30% in the small strain domain. This model is a good tool to describe, in the small strain domain, such material behavior, which shows plastic nonviscous phenomena.