Study on microstructure of rubberized recycled hot mix asphalt based X-ray CT technology

Micro-structural characteristics of recycled asphalt mixture have an important influence on its macro-mechanical performance. In this study, the discreteness, RAP dosage and asphalt film thickness of hot asphalt mixtures with recycled rubber were analyzed through CT scanning together with the IPP software. The recycled asphalt pavement (RAP) content was set as 25%, and the asphalt mixture specimens were produced in the laboratory. Different kinds of hot recycled rubber asphalt mixtures were produced to calculate the film thickness of the asphalt with five different asphalt dosages, 4.2%, 4.5%, 4.8%, 5.1%, and 5.4%, and three different aggregate particle sizes. From the results, it shows that the distribution of rubberized recycled hot mix asphalts can be analyzed by CT and considered as uniform, as the average particle size of aggregate on the left side is 2458.93 μm while the right is 2487.38 μm. The calculation of RAP dosage by CT technology is reliable. The RAP dosage is calculated to be 23.98%, and the actual error is 4.1%, relatively small. The asphalt film thickness of the rubberized recycled hot mix asphalt obtained by CT is reliable. It has strong, linear correlation with the asphalt film thickness calculated using the Hweem method. Asphalt film thickness increases with the increase in asphalt dosage under similar aggregate particle size, and asphalt film thickness increases with the decrease in aggregate particle size under the same asphalt dosage.