Pavement working platforms constructed with large-size unconventional aggregates

As a sustainable construction practice, recent research efforts of the Illinois Department of Transportation (DOT) have been focused on an engineered approach for developing construction specifications and performance validation of the use of large-size virgin and recycled unconventional aggregates in soft subgrade remediation. The Illinois DOT Bureau of Design and Environment has issued a special provision that specifies certain gradation bands for improved aggregate subgrade to allow enhanced use of large rocks from both primary crusher type virgin and recycled sources. Nevertheless, laboratory tests are usually inadequate for characterizing the properties and engineering behavior of large-size unconventional aggregates. Therefore, the recent field performance evaluation study using accelerated pavement testing was initiated at the University of Illinois with 12 full-scale pavement working platforms constructed with selected large-size virgin and recycled materials, including reclaimed asphalt pavement, recycled concrete aggregate, and demolition waste. For in-depth performance testing and evaluation, this paper describes test section construction and quality control sequences conducted at different phases of the study, including state-of-the-art field aggregate and pavement layer imaging techniques. The rutting performance trends of test sections were investigated in light of innovative test devices and techniques, including variable energy penetration testing, geoendoscopy, transverse ground-penetrating radar scans, as well as postfailure trenching images. Penetration of large rocks into the soft subgrade was effective in achieving a stable construction platform. Moreover, reclaimed asphalt pavement as a granular pavement layer was prone to large permanent deformations.