Evaluation of long-term performance of recycled aggregate base (RAB) layers and optimization of their design thicknesses

To reduce the use of natural aggregates commonly used in base layers, constructing recycled aggregate base (RAB) layers has gained popularity. However, in the literature, there is limited information about the engineering properties of recycled concrete aggregate (RCA) materials with different gradations and the blends of RCA and recycled asphalt pavement (RAP) materials. There is also a lack of practice in using a mechanistic-empirical (ME) design method to optimize RAB layer thicknesses. In this study, several full-scale test cells were built with RAB and natural aggregate base layers, and the physical and engineering properties of the base layer aggregates were determined in the laboratory. For long-term performance evaluation of the cells built in the field, falling weight deflectometer (FWD) tests were performed, rutting measurements were taken, and soil temperature was monitored over a period of two years. An ME design procedure was used to optimize RAB layer thicknesses.