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Clayey soils exhibit viscoelastic behaviour in the plastic state, implying simultaneous retentive and dissipative mechanical properties as well as strain rate dependent properties. Such response is partially captured by the socalled Atterberg plastic limits. A more comprehensive evaluation of the mechanical response of this type of soils in the plastic state can be obtained by testing in a dynamic shear rheometer. Clayey soils consisting of different proportions of kaolin and bentonite and different water contents were subjected to dynamic shear tests to measure their rheological properties. All tests were performed with a constant strain amplitude of 10%, a fixed range frequency sweep (0.1 Hz to 100 Hz) and a constant temperature of 20°C. The results show that the complex shear modulus has an inverse relationship with the soil water content and a direct relationship with the plasticity index. Moreover, the phase angle increases slightly and then decreases suddenly as the frequency increases. The complex shear moduli obtained by dynamic tests were compared with the oedometric moduli estimated by correlations and showed satisfactory trends between them. The study contributed to the understanding of the complex behaviour of soils in the plastic state. Although the mechanical response of these materials is affected by some factors, the plasticity limits were consistent with the complex moduli under analogous conditions of strain and frequency.

The paving-heavy crude oils (PHCO) are natural cut-back asphalts that can be used for unconventional paving solutions for low- and medium-traffic roads given their lower cost in comparison with conventional asphalt binders (i.e., produced through industrial oil refining). Despite their potential, the characterization and use of PHCO for road paving is still limited. This study focuses on assessing the adhesion quality and rheological properties of both unmodified and nano-modified asphalt residues (AR) obtained from two sources of PHOC. The results suggest that the AR offer smaller stiffness and develop asphalt-aggregate interfaces with lower adhesion quality as compared to those generated by the control conventional asphalt. In general, the nano-modifier addition led to lower stiffness values for the AR, and although it improved the adhesion in dry condition, the susceptibility to moisture damage at the asphalt-aggregate interfaces was not reduced. Future research is suggested to validate these findings by assessing asphalt mixtures., Los crudos pesados de pavimentación (CPP) constituyen asfaltos líquidos naturales que pueden ser empleados en soluciones de pavimentación no convencionales para vías de tránsito bajo y medio por su menor costo en comparación con el de cementos asfálticos convencionales (i.e., producidos mediante refinación de crudos de petróleo). A pesar de su potencial, la caracterización y el uso de CPP en pavimentación vial son aún limitados. Este estudio evalúa la calidad de la adhesión y las propiedades reológicas de asfaltos residuales (AR), no modificados y nano-modificados, obtenidos de CPP. Los resultados sugieren que los AR ofrecen menor rigidez y desarrollan interfases asfalto-agregado con menor calidad de adhesión que las generadas por el asfalto convencional de control. En general, el nano-modificador redujo la rigidez de los AR, y aunque mejoró la adhesión en seco, no redujo la susceptibilidad al daño por humedad en las interfases asfalto-agregado. Se sugiere investigación futura que valide los resultados a través de la evaluación de mezclas asfálticas.