Estudio para la mejora de mezclas asfálticas porosas con una selección multicriterio de aditivos y un nuevo betún modificado con polímeros

Resumen

Porous asphalt (PA) mixtures are becoming popular in recent decades in pavement application. These mixtures provide sustainable solutions to problems associated with dense-graded mixtures. The final pavements with these mixtures are quieter and safer than dense-graded pavements due to their high noise reduction and skid resistance characteristics. PA mixtures have a high amount of air voids (≈20%), which is achieved by lowering the fraction of fine aggregates. However, that makes them more prone to pavement distresses such as raveling, pothole formation, etc. The limitations of PA mixtures make them unsuitable for high traffic intensity. There is continual research ongoing to enhance the mechanical resistance of the PA mixtures so that their use can be more widespread. The present study is intended to thoroughly investigate the incorporation of additives and the use of modified bitumen for the enhancement of PA mix design and find novel and sustainable solutions to improve their resilience. This thesis presents a framework to improve the overall performance of PA mixtures by modifying the mixture parameters through the selection of additives and at the binder level through the development of polymer-modified bitumen. In the first phase of this research, the influence of a variety of additives on the mechanical, hydraulic, economic, and environmental performance of the PA mixtures was computed. The additives included aramid fibers, glass-hybrid fibers, cellulose fibers, and hydrated lime. Furthermore, a multi-criteria decision-making analysis was performed to quantify the benefits and limitations of the additives used and to allot a unified value considering their overall performance. The mechanical performance was computed based on Cantabro tests, indirect tensile strength, and moisture susceptibility. The impacts on hydraulic performance were obtained by laboratory testing that included volumetric analysis and permeability tests. Economic impacts were computed by initial investments required for the asphalt mixture produced per ton. The environmental impacts were computed using the ReCiPe method involving global warming potential, human toxicity potential, and marine aqua-toxicity potential. In the second phase, a new experimental bitumen was prepared with high vinyl content (>35%) to cater to the requirements of PA mixtures. The physical properties of the new bitumen were assessed by the penetration, softening, viscosity tests, while rheological properties were evaluated by complex modulus, phase angle, creep compliance, and fatigue behavior. Porous asphalt mixtures are prepared to see the effect of the addition of experimental bitumen. Among the most relevant results, it was found that the most promising fibers with considerable impact on the abrasion resistance were aramid pulp, which almost halved the particle loss. The lowest environmental impact was caused by the incorporation of cellulose fibers. While in the second phase of the research, it was concluded that the experimental bitumen prepared using high-vinyl SBS copolymer had higher stiffness, better fatigue behavior and higher creep recovery than the commercially used polymer modified bitumen.