Theoretical models to account for temperature and moisture effects on granular base course materials are developed. The models, based on a micromechanical approach that treats the granular materials as elastic spheres in contact, can be used to formulate temperature and seasonal adjustment factors for low-volume roads and to estimate when and where seasonal load restrictions are required. The thermal model relates the volumetric expansion caused by temperature increase to the increase of confining pressure, which results in an increase in the pavement modulus. The moisture model is based on thermodynamic laws and considers the granular materials as a two-phase system.One phase represents the soil particles, and the other phase represents an air-water mixture surrounding the soil particles. To verify the models, pavement layer temperatures and falling weight deflectometer deflection readings were taken at hourly intervals throughout the day on two pavement test sections at the texas transportation institute research annex. In addition, six farm-to-market roads in different regions of the state of texas were monitored. Deflection readings, rainfall data, and pavement temperature and suction readings were collected over a 10-month period. A coparison of the predicted moduli at different temperatures and moisture conditions with the backcalculated moduli from deflection basins is made to verify the models. An example problem of the application of the models for the predictive purpose is also presented. This paper appears in transportation research record no. 1252, Design, management, and operation of pavements.
Abstract