Performance grade asphalt repair composition

The present invention is a system for repairing asphalt. The system includes a discrete quantity of an asphalt repair composition located within a container and an induction heater. The composition is a combination of an asphalt binder, aggregate particles, and induction particles. The average diameter of the induction particles ranges from approximately 10% above to approximately 10% below an average diameter of the aggregate particles used in the composition. The induction heater heats the composition within the container by generating a magnetic field that penetrates the container. The magnetic field creates eddy currents in the induction particles. These eddy currents in turn heat the composition. Because the induction particles are distributed throughout the composition, the composition heats rapidly.

FIELD OF INVENTION

This invention relates to the field of materials and compositions and more specifically to compositions for the structural integrity of roads and runways.

BACKGROUND OF THE INVENTION

Military and civilian runways can incur sudden damage due to the impact of planes. This damage can include potholes, fissures and other surface irregularities. These surface defects can cause accidents when the relatively small wheels of a landing plane come into contact with them. Unanticipated repairs to prevent damage to planes can compromise military missions and disrupt civilian flights due to cancellations and diversions to safer landing areas.

Conventional methods of repairing asphalt concrete runways require heating of asphalt repair composition to allow the material to flow and compact to level the defective area. The heating process takes several hours, during which time runaways must be completely or partially closed. However, due to the time sensitive nature of military airfield traffic, repair crews may not have time for the composition to heat. Various attempts have been made in the art to use cold compositions to save time. However, cold compositions do not compact properly, and areas repaired in this manner develop deep ruts. While cold compositions may provide temporary repairs, they are unsuitable for extended use or use in a high-traffic area.

There is an unmet need for a composition suitable for rapid asphalt repair during mission critical military operations to avoid damage to military planes, and during commercial airline service to avoid damage to civilian planes, as well as injury to passengers.

BRIEF SUMMARY OF THE INVENTION

The present invention is a novel composition for asphalt repair that may be heated rapidly. The composition is a novel combination of an asphalt binder, aggregate particles, and induction particles having a specific structure. The average diameter of the induction particles ranges from approximately 10% above to approximately 10% below an average diameter of the aggregate particles used in the composition. An induction heater heats the composition within a container by generating a magnetic field that penetrates the container. The magnetic field creates eddy currents in the induction particles; these eddy currents in turn heat the composition.

TERMS OF ART

As used herein, the term “asphalt binder” refers to a semi-solid form of petroleum used to bind aggregate particles to create asphalt concrete.

As used herein, the term “compaction temperature” refers to a temperature that allows a user to create a particular density of an asphalt repair composition. Compaction temperatures can reach approximately 350 degrees F.

As used herein, the term “performance graded asphalt binder” refers to an asphalt binder that meets the specifications of ASTM D6373.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates an exemplary embodiment of an asphalt repair system100. System100includes an asphalt repair composition10for application to a pavement defect. Before application, composition10is heated in container20by induction heater30.

Asphalt repair composition10is made up of an asphalt binder11, aggregate particles12, and induction particles13. When heated, asphalt binder11becomes more fluid, allowing a user to densely pack composition10into a pavement defect. As asphalt binder11cools, it binds aggregate particles12and induction particles13to the pavement.

Certain embodiments of composition10may also include chemical anti-stripping additives, mineral fillers, and/or warm mix additives. Chemical anti-stripping additives are compounds added to asphalt binder to promote adhesion of asphalt binder to aggregate particles. Warm mix additives are mixtures added to asphalt binder to lower an asphalt repair composition's compaction temperature. Mineral fillers are mineral particles suspended in asphalt binder to improve the physical properties of an asphalt repair composition. Mineral fillers may include crushed aggregates, aggregate dust, hydrated lime, hydraulic cements, fly ash, loess, kiln dusts, or combinations thereof. Mineral fillers promote stability in composition10by filling in at least part of the voids which may be present in composition10. Hydraulic cements improve the strength of composition10. Hydrated lime, fly ash, and kiln dusts promote adhesion of asphalt binder to aggregate particles, as per the chemical anti-stripping additives.

Aggregate particles12provide much of the strength to composition10after application to a pavement defect. Aggregate particles12may include materials such as, but not limited to, gravel, crushed stone, recycled paving materials, slag, synthetic particles, and combinations thereof.

Induction particles13make up approximately 1% to approximately 20% of composition10. In the exemplary embodiment, induction particles13make up approximately 5% of composition10; however, other embodiments may include approximately 1% to approximately 10% of composition10. Induction particles13are similar in size and shape to aggregate particles12, and make similar contributions to the strength of composition10.

The average diameter of induction particles13ranges from approximately 10% above the average diameter of aggregate particles12to approximately 10% below the average diameter of aggregate particles12. This prevents a size disparity from affecting the strength and utility of composition10. As a result, induction particles13have an average diameter ranging from approximately 0.002 inches to approximately 1 inch. Induction particles13may include materials such as, but not limited to, graphite, tungsten, iron alloys, steel alloys, steel production byproducts, or combinations thereof. Steel production byproducts are materials other than steel produced during the process of steelmaking.

Container20is a container manufactured from a material that is transparent to a magnetic field; that is, induction heater30cannot heat container20through induction because the magnetic field passes through container20without effect. In the exemplary embodiment, container20is made from a non-metallic material capable of being heated to the compaction temperature of composition10without being damaged or deformed. In various embodiments, container20is a material such as, but not limited to, fiberglass, polymers, and combinations thereof. In the exemplary embodiment, container20holds approximately three gallons to approximately five gallons of composition10.

Induction heater30heats composition10in container20until composition10reaches a preferred compaction temperature. Induction heater30transmits a magnetic field at a frequency which creates eddy currents in induction particles13. These eddy currents create heat, which spreads through composition10until it reaches a preferred compaction temperature. At this point, a user may apply composition10to patch a pavement defect. The frequency of the magnetic field depends on the size of induction particles13and the amount of composition10. Because container20is non-responsive to induction, all inductive energy is transmitted to composition10.

It should be further understood that the drawings are not necessarily to scale; instead, emphasis has been placed upon illustrating the principles of the invention. Moreover, the terms “about,” “substantially” or “approximately” as used herein may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related.