Portland Cement Stabilized Full Depth Reclamation of the Pt. Michaud Beach Road

Many rural Canadian highways receive minimal levels of maintenance, in part due to reducing budgets, escalating costs, and the extensive degree of repairs needed throughout the pavement network. Portland Cement stabilized Full Depth Reclamation (PC-FDR) presents an attractive repair option for pavements suffering from subgrade and base failures as well as asphalt concrete deterioration. The Point Michaud Beach Road was selected as a candidate for evaluating the first PC-FDR in Nova Scotia. The asphalt concrete road exhibited extensive cracking and distortions that were indicative of base and subgrade failures while supporting very light traffic volumes. PC-FDR involves stabilizing a pulverized layer of asphalt concrete and granular base using small amounts (typically 4-6%) of Portland cement to provide a strong and frost-resistant base layer for supporting a new wearing surface, while minimizing the potential for reflective shrinkage cracking. A micro-cracking technique was also employed to further reduce the susceptibility of the material for large shrinkage cracks. Quality control of the microcracking process was performed using a Slab Impulse-Response test to monitor the reduction in the quasi-static stiffness of the stabilized material. Comparative testing before and after repair using Ground Penetrating Radar and a Falling Weight Deflectometer indicated a substantial increase in the predicted service life of the pavement. Prior to repair, twenty-two percent of the section was predicted to exhibit asphalt concrete fatigue failure in less than three years compared to less than three percent exhibiting fatigue failure in the stabilized material after twenty years of service, with no subgrade rutting or asphalt concrete fatigue failures. The combination of a full depth repair technique and the expected increase in durability will tend to reduce overall maintenance requirements and costs compared to conventional repair methods, counteracting the increased difficulty of managing infrastructure maintenance due to reduced budgets and escalating costs.