Other

Simon Adrianus Hesp

Raymond T Woodhams

Zhizhong Liang

A modified asphalt composition having improved low-temperature fracture properties is obtained by devulcanizing crumb rubber, preferably ground rubber tire. The devulcanization is effected without the use of harsh oxidizing treatments or the addition of potentially hazardous solvents, by fractional distillation of a mixture of the rubber and crude oil to a temperature at which substantially complete devulcanization occurs and harmful volatiles are driven off, around 300.degree. C. The resulting compositions are relatively inexpensive and simple to produce and, not having been oxidized, may be expected to show better long-term aging and fatigue performance compared to air-blown asphalts and the like. They are also preferable, on grounds of health and safety, to prior paving asphalts containing significant proportions of volatile organic aliphatic or aromatic hydrocarbons.

Process for preparing rubber-modified asphalt compositions

Insoluble particulate materials, which may be in solid or liquid form, are dispersed in a continuous non-aqueous phase and the dispersion rendered stable and resistant to phase separation by an in-situ stabilization procedure involving the formation of chemical bonds among the stabilizer components and to dispersed phases to form a network surrounding the particles which is compatible with the continuous phase. The invent ion has particular application for the formation of stabilized polyolefin-modified bitumen compositions for paving and other applications.

In-situ stabilized compositions

A stabilizer for bitumen-polymer compositions. Polyethylene-bitumen compositions having the polyethylene component dispersed throughout the solution and stabilized against gross phase separation are described. A method for preparation of the stabilizer includes vulcanization of a bitumen and amine-terminated poly(butadiene-co-acrylonitrile). Carboxylated polyethylene is coupled with the vulcanization product to obtain the stabilizer. Polyethylene dispersed in bitumen containing the stabilizer does not undergo gross phase separation and droplets in the 1 to 5 micron range are observed microscopically.

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Kingston, Canada

Simon Adrianus Hesp