Performance evaluations of pavement working platforms constructed with large-sized unconventional aggregates

With recent focus on sustainable construction practices and the ever-increasing transportation cost and scarcity of natural resources, use of unconventional aggregate materials, such as primary crusher run and concrete demolition waste, have become viable for the construction of pavement working platforms over very weak and often wet subgrade soils. To this end, a research study was undertaken at the Illinois Center for Transportation to evaluate the adequacy and field performances of such large-sized aggregate materials and validate new material specifications. A state-of-the-art image analysis technique was utilized to characterize the size and morphological properties, e.g. shape, texture and angularity of two large-sized aggregates, referred to herein as primary crusher run and crushed concrete. For the field evaluation, full-scale test sections were constructed with these large-sized aggregate materials over a very weak engineered subgrade and subjected to accelerated pavement testing. Construction quality control was achieved through in-place density and modulus measurements on conventional aggregate capping surface layers using nuclear gauge, lightweight deflectometer and soil stiffness gauge type devices. Periodic rut measurements were carried out on the pavement surface throughout the accelerated loading process using an Accelerated Transportation Loading Assembly (ATLAS). Contributions of the underlying pavement layers to the total rut accumulation was evaluated through innovative applications of ground penetrating radar (GPR), a light weight penetrometer device, known as the French Panda, as well as a geo-endoscopy probe. Layer intermixing and material migration at the aggregate subgrade and subgrade interface was found to improve the layer stiffness and pavement performance results significantly.