Sustainable Application of Quarry Byproducts Mixed with Large Size Unconventional Aggregates for Improved Performance

With recent focus on sustainable construction practices and the ever-increasing transportation costs and scarcity of natural resources, integration of large-size unconventional and marginally acceptable aggregates, such as quarry by-products (QB), and making their routine use in construction specifications is becoming imperative. In this study, the stability of large-size aggregates is increased by adding QB as sand- and smaller-sized particles to fill up the voids. Adding QBs is expected to increase density and provide stability for better aggregate interlock, and therefore, to increase the subgrade strength and eventually improve the road’s rutting performance. In order to determine the appropriate weight mix ratio of the large-size aggregates and the fine QB materials, a steel box with dimensions 610 mm by 610 mm by 533 mm was built to assess the packing of the two materials. One of the sides of the box was designed to have a transparent Plexiglas that enabled observation of the QB percolation into the voids of the large-sized aggregates, which were added in multiple lifts. The QB materials were then evenly spread on the surface of each lift and compacted with a laboratory-sized roller compactor. Different mix ratios, support conditions, and moisture contents of the QBs were investigated. The study concluded that 25% QB by the dry weight of the large aggregates is an appropriate amount to be used for both one- and two-lift construction practices of this composite weak subgrade replacement aggregate material, i.e., aggregate subgrade, in the field. The laboratory results will be implemented in the field by constructing test sections for unpaved construction platform and asphalt-paved low volume road applications and monitoring them for rutting performance using an accelerated pavement testing device.