A methodology for the analysis of asphalt age-hardening within a wide temperature-time aging domain has been implemented in France and Israel. The physical, rheological, and mechanical aspects of long-term asphalt age-hardening, involving straight-run and propane-precipitated asphalt cements have been presented previously. The results of that first stage of research were found to be quite promising with respect to the ability of long-term age-hardening analysis to provide a powerful and sensitive tool for characterizing the durability of asphalt cements, which in turn would correlate with the durability of actual bituminous paving mixtures. The aim of the second stage of the research was to correlate, explain, and predict the long-term aging characteristics of the asphalt with its fundamental rheological and physico-chemical properties. For this purpose, identical asphalt-cement samples were flown to France for a supplementary, comprehensive series of rheological testing and physico-chemical analysis. This paper describes the second stage of the research, which was performed on a bi-national level. The basic asphalt properties were extended to the long-term aging domain, and the long-term asphalt durability was related to some basic rheological and physico-chemical characteristics of the original, and standardly aged, asphalt cements.