A process for significantly decreasing the acid sludge settling time in waste oil recovery processes comprising the steps of heating used oil to a high temperature above 125 degrees Fahrenheit, cooling the heated oil, adding an oxidizing agent to the oil, allowing the acid sludge to settle within a period of approximately 24 to 72 hours, separating the acid-sludge-free oil from the acid sludge which settles out of solution as a result of addition of the oxidizing agent, providing said acid sludge to said process for converting acid sludge to asphalt products, and adding a polishing agent and separating the re-refined oil from the spent polishing agent. The process produces a high quality re-refined oil repidly and economically.

There is disclosed a novel pitch fluoride, which may be obtained by the direct fluorination of a pitch. The pitch fluoride of the present invention exhibits excellent properties comparable to those of the conventionally known graphite fluorides, such as excellent water-repellent and oil-repellent properties, etc. In addition, the present pitch fluoride has a unique property that it is capable of forming a film by vacuum deposition. The present film has substantially the same properties as those of the pitch fluoride and, hence, it is useful, for example, as a water-repellent and oil repellent coating for various substrates.

A chemically modified bitumen possesses phosphorus-containing functional groups which are capable of reaction to form a phosphorus-containing compound of a metal, preferably a polyvalent metal such as calcium, barium or zinc.

A process for its production involves reacting a bitumen with P₂S₅ or P₂₀₆, optionally followed by hydrolysis. In another aspect the modified bitumen is further reacted to form a phosphorus-containing metal compound modified bitumen.

The modified bitumens, particularly the metal- compound type, possess improved fatigue resistance properties, such as relaxation time and initial tensile modulus.

This invention relates to the modification of bitumen by polymeric materials used particularly for the preparation of asphalt mixtures with enhanced mechanical properties, wherein the polymeric materials are selected from additives capable of forming a supramolecular assembly. The modified bitumen may be used for the fabrication of asphalts mixtures with mineral aggregates used in construction or maintenance of sidewalks, roads, highways, parking lots or airport runaways and service roads and any other rolling surfaces.