STP662: Recycling Old Asphaltic Pavement with Sulfur

    McBee, WC
    Metallurgist and research chemist, U. S. Department of the Interior, Bureau of Mines, Boulder City, Metallurgy Engineering Laboratory, Boulder City, Nev.

    Sullivan, TA
    Metallurgist and research chemist, U. S. Department of the Interior, Bureau of Mines, Boulder City, Metallurgy Engineering Laboratory, Boulder City, Nev.

    Saylak, D
    Associate research engineer, Texas Transportation Institute, Civil Engineering Department, Texas A&M University, College Station, Tex.

    Pages: 19    Published: Jan 1978


    Abstract

    Recycling asphaltic concrete pavements was investigated as a means of utilizing the asphalt and graded aggregates they contain and solving waste disposal problems. Discarded asphaltic concrete pavement materials from three sources in the Las Vegas, Nev. area were studied; each contained a different aggregate base material. Laboratory testing showed that all three source materials could be recycled successfully into quality pavement materials, with properties comparable to those of virgin asphaltic concrete. This successful recycling was accomplished by a combination of procedures including controlled heating of the material to be recycled, sulfur and asphalt additions, and remixing. Further, a controlled-heating capability was essential to prevent unnecessary oxidation of the asphalt binder. Sulfur additions of 16 to 26 weight percent of the binder successfully reduced the viscosity of the age-hardened asphalt, at the mixing temperature, to levels comparable with those of virgin asphalt. Resilient moduli of sulfur-recycled materials were higher than those of conventional asphaltic concretes, because of the structuring effect provided by the sulfur in the mixture at ambient temperatures. Fatigue properties of the materials were found to be equal to or better than those of asphaltic concretes, indicating that a pavement life comparable to that of normal asphaltic concretes could be expected. Pavement materials recycled with sulfur were also found to be superior to those recycled with a softening agent in that higher softening points and lower penetration values were obtained, both of which would increase the life expectancy and decrease the potential for rutting in the recycled pavements. Successful testing of the sulfur-recycling procedures demonstrated on a laboratory scale makes it attractive now to consider full-scale field tests to evaluate the performance of the recycled pavements under actual road conditions.

    Keywords:

    bitumens, flexible pavements, circulation, asphalts, sulfur, softening agents, additives, fatigue (materials), variations, softening points, Marshall properties, density (mass/volume)


    Paper ID: STP35778S

    Committee/Subcommittee: D04.95

    DOI: 10.1520/STP35778S


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