Effect of mixing time on reclaimed asphalt mixtures: An investigation by means of imaging techniques

This paper presents an application of imaging techniques to investigate the distribution of reclaimed asphalt and air voids within gyratory compacted specimen. Stone Mastic Asphalt specimens containing reclaimed asphalt, were produced at five different laboratories participating in the collaborative project Re-Road: University of Nottingham, Belgium Road Research Centre, Danish Road Directorate, TU Braunschweig and Laboratoire Centrale de Ponts et Chaussees (now IFSTTAR). This study applies the X-ray Computed Tomography and Optical Microscopy techniques to view the internal structure of the specimen with particular focus on the air voids and reclaimed asphalt distributions within the specimen. The observations revealed that with doubling the mixing time the reclaimed asphalt is well mixed with the fresh materials within the gyratory compacted specimen and also the air voids distribution along the specimen height result to be more consistent.