THE INFLUENCE OF METAL-CONTAINING COMPOUNDS ON ENHANCEMENT AND INHIBITION OF ASPHALT OXIDATION

Addition of lime to paving asphalts is known to inhibit oxidative agin g of pavements. The mechanism of the action of lime in retarding oxida tion is not known. In this work, an asphalt was mixed with a vanadium chelate that is known to strongly promote oxidation in asphalts. This enhancement of oxidation was largely neutralized when the mixtures wer e combined with hydrated lime. It is possible that lime acts by suppre ssing the catalytic activity of naturally occurring vanadium compounds that occur in almost all asphalts, although other mechanisms for the action of lime are also possible. The use of vanadium compounds in asp halt aging tests also is discussed.