Comprehensive performance evaluation of in-place recycled hot mix asphalt as unbound granular material

A promising pavement rehabilitation (or reconstruction) strategy that is of interest to state highway agencies and local governments involves the in-place pulverization of failed hot mix asphalt (HMA) pavements and re-use of the pulverized material as a granular base material. Advantages of this technique include a reduction in the use of virgin aggregate, a reduction in the amount of construction traffic, and removal of the potential for reflective cracking from the existing cracked pavement layers through the new HMA surface. However, the performance of this technique has not been comprehensively evaluated, and, in particular, permanent deformation characteristics.;In this thesis, four pilot projects in northeastern California were used to evaluate the pulverized material and this rehabilitation strategy. The characteristics and performance of the pulverized material were evaluated by comprehensive laboratory and field testing, and analyses. Field resilient response was evaluated using dynamic cone penetrometer (DCP) test and falling weight deflectometer (FWD) test results. Visual condition surveys were conducted to monitor field permanent deformation responses and distresses. These field tests were used to track the long-term performance of the pavement structure. Triaxial testing, including static shear tests, resilient modulus tests and extensive repeated loading tests, was used to investigate the resilient and permanent deformation characteristics. Laboratory index testing, including sieve analyses, Atterberg limit tests, compaction tests, permeability tests, and aggregate shape tests, were performed to evaluate the basic properties of the pulverized material and construction quality in the field.;Based on the multistage repeated load triaxial test results, the shakedown limits of the pulverized material were estimated and compared with the stress states calculated from the cross-anisotropic finite element analyses based on real traffic and climate data. A recursive-incremental damage model was used to predict permanent deformation of the pulverized base layer over the long term and to compare it with that of typical aggregate base material.;Based on the comprehensive laboratory testing, field testing, and analyses, the pulverized material was found to be generally stiffer than typical aggregate base material, possibly due to better aggregate shape than that found in typical aggregate base material. The pulverized material has less permanent deformation resistance at low stress levels but greater resistance at higher stress levels than typical granular material used in California. Possible reasons for the lower permanent deformation resistance at low stress levels might be the laboratory compaction method and that the recycled HMA in the pulverized material undergoes additional breakdown under initial loading since coarse fractions of the pulverized materials are greater than that of the comparison virgin aggregate base. Overall, the performance benefits of this rehabilitation strategy make it a viable option for flexible pavement rehabilitation.