"Small amounts of nitrogen-containing materials are frequently added to asphalts to improve the resistance of asphaltic pavements to moisture damage. Synfuel-derived materials containing pyridine-type nitrogen from shale oil- and coal-derived liquids appear promising for use as asphalt modifiers in paving applications. Addition of shale oil basic nitrogen materials to petroleum asphalts increased the resistance of asphalt-aggregate briquettes to moisture damage as measured by a water susceptibility test. A newly developed technique was used to study the interactions of basic nitrogen compounds with aggregate surfaces by temperature-programmed thermal desorption of nitrogen compounds from aggregates followed by chemiluminescent determination of the evolved nitrogen. Shale oil and coal distillate materials were evaluated as recycle agents for restoring useful properties to aged asphalts recovered from pavement cores. Addition of these materials to recovered, aged asphalts generally increased the rate of age hardening compared with commercial additives, probably because the synfuel materials themselves lacked stability."