INFLUENCE OF COARSE AGGREGATE CONTENT IN RECYCLED ASPHALT MIXTURES ON RUTTING AND RESILIENT MODULUS

Abstract

The use of recycled asphalt (RAP) as a road maintenance material has been widely applied. The use of RAP is expected to reduce maintenance costs and have a positive impact on the environment. This study assesses the performance of recycled asphalt mixtures that undergo changes in gradation within the coarse aggregate (CA) fraction and the asphalt aging process, resulting from traffic loads and weather fluctuations. Four mixture variations were designed using different coarse aggregate (CA) contents of 39%, 35%, 27%, and 23%, representing progressive material degradation levels corresponding to field aging conditions. Each mixture was tested for rutting and resilient modulus under controlled temperature and loading cycle to evaluate performance degradation. Tests included Marshall tests, resilient modulus (MR), and wheel tracking tests. Results indicate that susceptibility increases with higher temperatures and lower CA, while the resilient modulus decreases linearly (r = 0.995, R² = 0.88). A 16-22% increase in rut depth and a 35-42% reduction in MR were observed when CA decreased from 39% to 23% at 50 °C. Rutting behavior and deformation rates, influenced by temperature and decreasing CA content, were found to be strongly correlated in each mixture variation. These conditions provide information on the tendency of recycled mixtures to undergo degradation and asphalt aging processes, serving as a guide for determining the optimal time to carry out the recycling process. Economic calculations optimize the use of new materials in road maintenance through recycling.