Abstract Manager

Cold-in place recycling (CIR) has gained recognition as a sustainable, cost-effective method for rehabilitating pavements in regions with harsh climates and low subgrade stiffness. This case study examines a CIR project conducted in the summer of 2024 on Road 170 in Saguenay, northern Quebec, with the primary goal of assessing the roadway’s structural characteristics using the Light Falling Weight Deflectometer (LFWD). During the recycling process, the existing asphalt pavement was milled, processed, mixed with binding agents, and then reinstalled as a new base course layer. To evaluate the in-situ stiffness and monitor the curing behaviour of this rehabilitated layer, LFWD testing was conducted immediately after compaction and after 1, 2, 4, and 24 hours. At each test location, four LFWD tests were conducted to evaluate the transversal uniformity, while surface temperature was recorded for temperature corrections.

Back calculation was used to calculate the stiffness of the recycled layer, with temperature corrections applied to standardize stiffness values to 25 °C, enhancing the reliability and comparability of the measurements. The results showed a progressive increase in stiffness over time, indicating that CIR layers can achieve stiffness much higher than unbound materials. This study emphasizes the importance of incorporation LFWD testing into CIR projects, with the assessment of the curing of the recycled materials. Ultimately, CIR supports sustainability goals by recycling existing pavement materials on-site while reducing construction time and environmental impact.