Cement Stabilization of Conventional Granular Base and Recycled Crushed Portland Cement Concrete

The performance of typical thin flexible pavement systems depends on the quality of the granular base course. The granular base is responsible for mitigating strains on the subgrade, preventing fines pumping, and managing drainage. Field conditions including high water tables, increased precipitation, and poor subgrade conditions often lead to water pumping and fines migration into granular bases in urban areas. Furthermore, current construction practices favor the use of granular base materials with fines contents at the high end of the base course specifications, as higher fines base courses are thought to be more easily compacted. Additionally, the use of recycled materials is becoming more common, with the natural aggregate source depletion and waste reduction measures in many urban areas. This study examined the effects of increasing fines contents on a conventional City of Saskatoon (COS) granular base material as well as an impact-crushed recycled Portland cement concrete (PCC) aggregate. Gyratory compaction and rapid triaxial frequency sweep characterization were performed on samples with varying fines contents. The results of this study showed that increasing the fines content of the conventional COS granular base improved its compactibility. However, increasing the fines content of the PCC granular base material did not offer substantial improvements in compaction behavior. The mechanistic material results showed that the increased fines contents lessened the mechanistic material stiffness properties of both materials, although the effects of increased fines were often less pronounced with the PCC material.