Asphaltic concrete recycling apparatuses, process and system

• US 4,256,414 A
• Filed: 01/25/1979
• Issued: 03/17/1981
• Est. Priority Date: 01/25/1979
• Status: Expired due to Term

• Current Assignee: James L. Milligan
• Original Assignee: James L. Milligan
• Inventors: Milligan, James L.
• Primary Examiner(s): Byers, Jr., Nile C.
• Application Number:
  US06/006,275
• Time in Patent Office: 782 Days
• Field of Search: 404/79, 404/77, 404/72, 404/80, 404/91, 404/92, 404/95, 427/138, 366/61, 366/64, 366/1, 366/25, 126/343.5 A
• US Class Current: 404/79
• CPC Class Codes: E01C 19/1004 Reconditioning or reprocessing bituminous mixtures, e.g. salvaged paving, fresh patching mixtures grown unserviceable; Recycling salvaged bituminous mixtures; Apparatus for the in-plant recycling thereof E01C19/1036 takes precedence
• CPC Class Codes: E01C 23/065 Recycling in place or on the road, i.e. hot or cold reprocessing of paving in situ or on the traffic surface, with or without adding virgin material or lifting of salvaged material; Repairs or resurfacing involving at least partial reprocessing of the existing paving in situ mixing of hydraulic cement concrete E01C19/025; apparatus for in-plant recycling E01C19/1004, E01C19/1036

Abstract

Weathered asphaltic concrete road surface material is mined at each of a series of road locations and heated at or near the site of mining and future laydown to form particulate agglomerates of aggregate and asphalt in a form receptive to asphalt rejuvenation additives, mixed with such asphalt additives and passed to a laydown apparatus and returned to a road location near or at that location from which the weathered asphaltic concrete was initially taken. The steps of mining, rejuvenation and laydown and related storage and screening are simultaneous and continuous.

Claims

1. An asphalt pavement recycling system comprising an asphalt treatment apparatus, treatment apparatus feed and product conveyor units, and an asphalt concrete laydown apparatus,

said treatment apparatus comprising a bin, a screen oversize conveyor, a heater assembly, a reagent adder, a pug mill, a hot storage bin and treatment apparatus input and discharge conveyors and reserve pile conveyor,

said heater apparatus comprising a heater frame, a chamber upper shell, a chamber lower shell, a feed support plate and a conveyor assembly, said frame comprising rigid longitudinally extending frame members, transversely extending members vertically extending frame members firmly joined together and supporting said shells and elements of said conveyor assembly and support plate,

said upper shell of the heater assembly comprising a vertical left wall, a vertical right wall and a horizontally extending roof joined together to form a downwardly open U-shaped hood, said horizontal flat rigid plate firmly supported on the frame and near the bottom of said upper shell in a heater chamber within the said heater assembly walls,

said conveyor assembly extending from beyond a discharge end of the heater chamber past a feed end thereof to below a feed hopper, said feed hopper operatively near said support plate, said conveyor assembly comprising a front or discharge gear wheel and a feed or rear gear wheel, an upper chain flight and a lower chain flight each carrying drag blades, a motor supported on said frame operating upon a gear to drive the chain flights,

a horizontally extending and horizontally elongated space on each side of said heater chamber between the upper heater chamber shell and the lower chamber shell, said space extending vertically above the top of chains and said drag blades are carried above and along and in contact with said support plate in said heater chamber,

said treatment apparatus input conveyor feeding into said feeder bin, said bin discharging to and attached to the feed end of said heater apparatus to feed slabs into said treatment apparatus and a heater apparatus discharge screen operatively adjacent a discharge end of the heater apparatus, a pug mill attached to the screen and arranged to receive the undersize of the discharge screen,

said pug mill operatively attached to a reagent feeder, a discharge of said pug mill emptying into said hot storage tank, said storage tank discharging by a said discharge conveyor to the treatment assembly product conveyor, said conveyor connected to said laydown apparatus.

2. System as in claim 1, and comprising a tractor, each of said asphalt treatment apparatus, treatment apparatus feed and product conveyor units, and asphalt concrete laydown apparatus having a mobile support.

3. An asphaltic concrete treatment heater apparatus comprising a longitudinally extending heater frame, heater chamber upper shell, heater chamber lower shell, heater chamber feed support plate and a conveyor assembly, said frame comprising rigid longitudinally extending frame members, transversely extending members and vertically extending frame members firmly joined together and supporting said shells and elements of said conveyor assembly and support plate, and chamber heating means,

said chamber upper shell comprising a longitudinally and vertically extending left wall, a longitudinally and vertically extending right wall and a horizontally and longitudinally extending roof of thermal insulating material joined together to form a longitudinally extending downwardly open U-shaped hood, said feed support plate having a horizontal flat rigid portion firmly supported on said frame and near the bottom of said upper shell in a heater chamber formed within the said roof and walls, said chamber heating means operatively connected to the interior of said heater chamber,

said conveyor assembly extending from beyond a discharge end of said heater chamber past a feed end thereof, said conveyor assembly comprising a discharge end gear wheel and a feed end gear wheel, a pair of upper chain flights and lower chan flights, each upper and lower flight of the pair connected to each other, each flight formed at a series of pivotally joined rigid links and said pair of flights carrying a series of rigid drag blades, means supported on said frame operating upon said gears to drive said chain flights,

a horizontally extending and horizontally elongated space on each side of said heater chamber between the upper heater chamber shell and the lower chamber shell, said space extending vertically above the top of said chain flights, and said drag blades are carried above and along and in contact with said support plate in said heater chamber, said drag blades resting on said feed support plates and uniformly longitudinally spaced from each other on said plate, and each drag blade spaced apart from the other by a plurality of links of said chain flights.

4. Apparatus as in claim 3 wherein the heating means comprises a plurality of fuel burners each said burner having a flame axis directed parallel to the length of the roof and walls of said heater chamber.

5. A process of treating weathered embrittled asphalt concrete located in a roadbed portion comprising a mixture of asphaltic concrete by:

(a) first removing embrittled asphaltic concrete from its location on the roadbed in the form of dimensionally stable generally flat slabs of asphaltic concrete, said slabs each 1 to 3 inches thick and 6 to 12 inches wide and 6 to 12 inches long;

(b) passing such slabs onto a support plate within a heater chamber and moving said slabs through such chamber while heating them by directing flames at the walls and roof of said heater chamber whereby said slabs are heated by radiation and in a neutral atmosphere and thereby

(c) raising the temperature of the asphaltic concrete until the asphalt component thereof melts and decomposes the initially dimensionally stable slabs into a flowable mass of discrete particulate agglomerates at a temperature below 200°

C. and passing hot gasses from said chamber with negligible contact with said mass, each of said particulate agglomerates comprising a mass of aggregate with an asphaltic covering thereon, and then adding asphalt rejuvenating material to said mass, then

(d) passing such rejuvenated mixture of asphalt and aggregate to a zone of the roadbed whereat such rejuvenated asphaltic concrete mix is applied.

6. Process as in claim 5 wherein the particulate agglomerates have an average size of less than 1/4 inch diameter.

7. Process as in claim 5 wherein the amount of additive varies in range from 0.2 to 0.4% of weight of the slab material fed to the heater chamber.

8. The process of claim 7 wherein the weathered asphalt concrete contains asphaltenes and components chosen from the group consisting of nitrogen bases, first acidaffins, second acidaffins and paraffins, said asphalts having a ratio (N+A₁)/(P+A₂) equal to Ra, where N, A₁, A₂, and P are respectively the weight percent of the nitrogen bases, first acidaffins, second acidaffins, and paraffins present in the asphalt to be treated and said additive comprises an aqueous emulsion of a petroleum oil substantially free of fractions boiling below about 160°

C. at 10 millimeters of mercury absolute pressure, substantially free of asphaltenes and containing components chosen from the group consisting of nitrogen bases, first acidaffins and second acidaffins and paraffins and having a ratio R₀ equal to about from 0.01 to less than about 19 where R₀ is equal to N'"'"'+A'"'"'₁ /P'"'"'+A'"'"'₂ where N'"'"', A'"'"'₁, A'"'"'₂ and P'"'"' are respectively the weight percent of the nitrogen bases, first acidaffins, second acidaffins and paraffins present in said petroleum oil, said asphalt and said oil being employed in the ratio (Z) of the weight of oil to the weight of asphalt to form a treated asphalt of ratio R equal to

space="preserve" listing-type="equation">N"+A".sub.1 /P"+A".sub.2

where N", A"₁, A"₂, and P" are each respectively the weight percent of the nitrogen bases, first acidaffins, second acidaffins and paraffins in said treated asphalt where P" is less than about 40%, said asphalt of ratio R_a and said oil being employed in the ratio Z, where ##EQU2## where R is a value in the range from about 0.4 to about 10; and

where R_a is less than 0.4, R is larger than R_a ; and

where R_a is more than about 10, R is less than about 10 and less than R_a.

9. Process as in claim 8 wherein the oil may have an initial boiling point at 10 millimeters mercury absolute pressure of above about 160°

C., and is substantially free of fractions boiling below about 200°

C. and P'"'"' may vary from about 5% to about 95% and the value of Z is not greater than that sufficient to produce an asphalt of penetration of not more than 300.

10. Process as in claim 7 wherein the additive is a highly aromatic petroleum extract oil having a viscosity between about 70 and about 8000 SSU at 100°

F., a viscosity-gravity constant greater than about 0.90, and a flash point above about 300°

F., and consists essentially of aromatic-type hydrocarbons substantially free from asphalteens, olefines, and cracked hydrocarbons.

11. Process as in claim 5 wherein the rejuvenated asphaltic concrete mix is applied to the roadbed from which removed.