ABSTRACT
Quarry Byproducts (QBs), usually less than 6 mm in size, are the residual deposits from the production of required grades of aggregate and often stockpiled in excess quantities at the quarries. Recent research at the Illinois Center for Transportation has focused on investigating the performance of large-size aggregates mixed with QB for constructing subgrade replacement and subbase over weak soils. Such a sustainable application linked to commonly used rockfill practice for building construction platforms and low volume road applications over soft subgrade would improve the stability when large aggregates are mixed with QB materials. The appropriate weight mix ratios of the large-size aggregates and the fine QB materials were determined via a laboratory packing study. A combination of 30% dry QB by the weight of the large rock and 25% QB with a moisture content of 2.5% were found to be the optimum quantities of QB to be mixed with the large-size rock on top of a soft subgrade. In the field, two test sections were built to study the construction platform application by shaking and compacting the QB on top of large, 100 to 150 mm, size aggregate materials in one and two lifts using a vibratory roller compactor with the goal to construct a 530-mm layer, topped with 76-mm of regular-sized dense graded capping aggregate material. Other two test sections that were also built as the exact replicates of the construction platform sections were paved with an additional 100-mm thick hot mix asphalt surface to study the low volume road application. Performance monitoring of the unpaved construction platform sections indicated that both the one-lift and two-lift sections showed a good performance under a heavy wheel load by accumulating less than 76 mm of rutting after 20,000 load repetitions.
