Correlation Between Cold Recycled Mixture Triaxial Parameters and Conventional Mechanical and Volumetric Properties

The asphalt paving industry is trying to leverage cold-mix technologies to decarbonize its processes. Accordingly, the use of cold recycled mixtures (CRM) in road construction and rehabilitation has become a promising area of development, along with the necessary circular economy trends. This investigation studied four CRM made from 100% reclaimed asphalt pavement (RAP) and various emulsified asphalt contents (ranging from 2.0 to 3.5%). Test specimens were produced by compacting the various mixtures using 100 Superpave Gyratory Compactor (SGC) gyrations. Specimen volumetric properties were obtained, and the moisture resistance was analyzed using the indirect tensile strength (ITS) test. However, recent research shows that CRM has a highly stress-dependent mechanical behavior. In this sense, triaxial tests have proven to be a more effective way to provide a deeper characterization of CRM and thus improve their design. In this research, two types of triaxial tests were performed: monotonic triaxial tests with different confining pressures (ranging from 25 to 200 kPa), from which the shear parameters (cohesion and internal friction angle) were obtained, and cyclic triaxial tests, used to obtain the nonlinear Resilient Modulus (RM). However, triaxial tests are complex and time-consuming. After a statistical study of the results, fitted regression models showed a promising adjustment, explanatory of the trends of the triaxial results of the studied CRM. After further validation and refinement, these relationships could lead to improved methods for estimating CRM resilient behavior.