Utilization of existing recyclable materials has always been key to more efficient and economical highway construction. Use of the foamed-asphalt (FA) technique to stabilize recycled asphalt pavement (RAP) is one strategy for an efficient use of salvaged construction materials. The main objective of this study is to investigate the potential use of FA-treated RAP as a base course material in lieu of a crushed-limestone base beneath a concrete pavement layer. Test sections were constructed at US-190 near Baton Rouge, Louisiana, and used for field evaluation of the FA RAP base. The laboratory mixture design of the FA RAP, the construction of the experimental base section, and the field evaluation of the stiffness of the FA RAP base layers using different in situ testing devices are presented. Preliminary results of both laboratory and field tests showed that the FA-treated RAP mixtures are very promising and can be used as an alternative to the traditional limestone base beneath a concrete pavement layer.