Advancing recycled pavement performance monitoring with fiber optic sensing

The reuse of existing materials instead of virgin material is becoming increasingly popular in the construction of road pavements worldwide, as it increases the sustainability of the pavements. In the case of severely deteriorated asphalt pavements, interventions beyond the bottom of the asphalt layers are required. To limit the time required for rehabilitation, Cold In-Place Recycling (CIPR) has proven to be an effective means of significantly shortening the construction phase and ensuring cost efficiency. However, robust testing and structural monitoring is required to ensure the long-term performance of the recycled pavement.

This research presents a possible integration of non-destructive monitoring methods for the purpose of investigation, such as the Falling Weight Deflectometer (FWD) commonly used for testing conventional pavements, and more advanced inspection tools such as fiber optic sensors. As the latter represent a relatively costly approach, the selection of suitable locations for their installation both along and in the depth of the pavement is crucial to obtain meaningful information. To investigate this crucial issue, a CIPR pavement with foamed asphalt as base stabilizer was considered for monitoring. Preliminary investigations allowed the critical failure locations of the pavement to be defined so that the fiber optic sensors could be installed at the appropriate depth. Thereafter, continuous real-time monitoring with fiber optic sensors, supported by FWD testing at regular intervals for validation purposes, enabled a long-term assessment of the structural soundness of the pavement, which is a prerequisite for maintaining resilient road structures.