EVALUATION OF SELECTED SOFTENING AGENTS USED IN FLEXIBLE PAVEMENT RECYCLING

Twenty-three softening agents were tested for physical and chemical properties. The agents were very low in viscosity, which seemed to correspond to a low asphaltenes two pavements being considered for recycling. Approximately 1 percent of the Dutrex and Dust Oil additives were needed to reduce the extracted asphalts to the AC5 level. About 1 1/2 percent Reclamite was required to reach the AC5 level, and an excess of 2 percent Flux Oil was needed. The AC5 consistency was not achieved for pavement No. 1 using the Flux Oil, due to the fact that so much agent was needed that the precentage of air voids was reduced to an intolerable level. Similar relationships for the viscosity at 275 deg F (135 deg C), penetration and ductility were observed. The mix properties stability, air voids, creep compliance and resilient modulus were measured for binder consistencies of AC20, AC10 and AC5 using the four agents. Both the asphalt consistency and the total binder content affected these values. Samples containing the four agents were oven aged to evaluate changes in the mix and binder properties. /FHWA/