Effects of Gradation and Aged Binder Content of (RAP) on Properties of Cold-Recycled Asphalt Mix

Cold-recycling of asphalt is an effective method enabling agencies to conserve valuable resources during rehabilitation of distressed roads.

At Twining, we are continuously seeking to improve our understanding of cold-recycled asphalt performance and investigate the impact of the Recycled Asphalt Pavement (RAP) gradation and RAP binder content on properties of cold-recycled asphalt at a given recycling agent and water content level. Then we evaluate the effect of recycling agent content and water content levels on the performance of Cold-Recycled asphalt.

We conducted experiments where various RAP sources with controlled gradations and five different asphalt content levels were mixed with emulsion at two different dosages and tested for performance properties; including Marshall stability and moisture susceptibility.

The results show that at early stages of curing, the effect of gradation of RAP is more important than the aged RAP binder content. Moreover, at this stage, increasing emulsion content improves wet stability and moisture susceptibility of the samples regardless of the RAP binder content and gradation of the cold-recycled mix.