Long-term performance of flexible pavement structures in a changing climate

Abstract: Climate changes may cause an increase of precipitation in the Province of Quebec over the next decades. As the performance of flexible pavement structures is closely related to moisture content of soils and aggregates, these structures can be considered vulnerable to climate changes. In order to quantify the effect of future precipitations increase on the pavement service life, this research project was based on a three steps approach: 1) Establishment of a relationship between precipitations and water content in the subgrade layers; 2) Establishment of the relationship between soils water content and soils mechanical properties, quantified with the resilient modulus and the permanent deformation behaviour; 3) Quantification of the effect of increased precipitations on pavement life, based on modification of their mechanical behaviour due to water content increase. For the example considered in this paper, it was found that the service life of pavement structures submitted to future climate may present a service life reaching 0.72 times the service of actual pavement structures. These results vary depending on the soil and damage types considered. Long-term performance of flexible pavement structures in a changing climat

Resilient modulus and segregation potential estimation from simplified laboratory procedure Resilient modulus and segregation potential estimation from simplified laboratory procedure

Abstract: Design of flexible pavements in regions submitted to seasonal freezing conditions requires a good knowledge of the soil resilient modulus and frost sensitivity. As the tests used for a detailed characterization are complex, costly and require experienced staff, these important design parameters are too often reduced to default values. However, many estimation approaches exist to easily obtain these parameters. New tools such as portable light weight deflectometer and percometer give the opportunity to implement estimation equations based on the soils response measured by these apparatus. A simplified laboratory procedure involving a 300 mm diameter PVC mold was developed in order to obtain the resilient modulus and the segregation potential of various subgrade soils using measurements from portable light weight deflectometer and percometer. The use of the portable light weight deflectometer for resilient modulus characterization is suitable as the short pulse load obtained with this apparatus produces a deflection in the elastic range causing the materials to react similarly to what is encountered in the field. The proposed procedure also allows taking into account the stress dependency of the resilient modulus. Regarding frost susceptibility, the percometer allows obtaining rapid dielectric constant measurement, which was often associated with the segregation potential, on the same sample used for mechanical characterization. In combination with geotechnical characterization parameters, estimation equations were proposed to obtain subgrade soils segregation potential and the resilient modulus from portable light weight deflectometer and dielectric constant measurements