Design and mechanical properties of foamed asphalt stabilized base material

Foamed asphalt stabilized base (FASB) combines reclaimed asphalt pavement (RAP) and/or recycled concrete (RC) with a foamed asphalt binder. The pavement structural properties of FASB fall somewhere between conventional graded aggregate base (GAB) and hot mix asphalt (HMA). Therefore, the required thickness of the pavement section can be reduced, resulting in cost savings in addition to recycling benefits. Mix designs were developed for eight different combinations of RAP, RC, and GAB. Details of the mix design procedure and the effects of factors representative of design and field conditions are evaluated. Triaxial test specimens from the weakest and strongest mixtures were tested for dynamic modulus and repeated load permanent deformation resistance, which can be used as inputs to the new AASHTO mechanistic-empirical design procedure. The measured stiffness values were also used to determine an appropriate structural layer coefficient value for use in the AASHTO empirical pavement design method.