Influence of Mixing Time and Production Temperature on the Performance and Circularity of Recycled Asphalt Mixtures: Evidence from the Brazilian Context

The pursuit of alternative materials and more circular production methods in the paving sector has intensified in response to raw material scarcity and waste generation caused by linear practices. The use of reclaimed asphalt pavement (RAP) in asphalt mixtures emerges as an effective solution under sustainability principles. Considering the current Brazilian context regarding pavement recycling, this study evaluated the influence of laboratory variables—mixing time and production temperature—on the mechanical performance of recycled asphalt mixtures, and assessed circularity and economic efficiency regarding the incorporation of 15% RAP into new mixtures. The research comprised four stages: (i) characterization of aggregates, virgin binder, and RAP, followed by mixture design; (ii) definition of four production protocols (Protocol I: 100 s, RAP at 165 °C; Protocol II: 200 s, RAP at 165 °C; Protocol III: 100 s, RAP at 27 °C; Protocol IV: 200 s, RAP at 27 °C) and mechanical testing; (iii) circularity assessment; and (iv) cost estimation. No statistically significant differences among the compared protocols were detected for the volumetric parameters. Protocol I showed the most favorable mechanical performance based on the tests conducted across all four protocols, including higher stiffness. Statistically significant differences associated with production temperature were detected for some mechanical outcomes, whereas no statistically significant differences associated with mixing time were detected. In the additional durability assessment, Protocol I showed significantly greater fatigue resistance than the control mixture at the 50% stress level, while no statistically significant difference in resistance to permanent deformation was detected between these mixtures. Mixtures with RAP heated at 165 °C achieved the highest circularity indices. RAP use reduced production costs by 9.66% per kilometer. These findings support the technical, environmental, and economic feasibility of RAP incorporation under the conditions investigated, with Protocol I showing the most favorable overall performance among the protocols based on the tests conducted across all four production conditions.