Road structure – process – or apparatus – Process – Heating
Reexamination Certificate
1998-05-04
2001-02-13
Lisehora, James A. (Department: 3673)
Road structure, process, or apparatus
Process
Heating
C404S092000
Reexamination Certificate
active
06186700
ABSTRACT:
This invention generally relates to the recycling and use of roofing waste, including shingles, tar paper and portions thereof, and more specifically to composition, method and use of reduced roofing waste materials as a patch for potholes and a paving for roads, driveways, walkways and the like.
Methods and apparati for manufacturing asphalt paving compositions for roadways and the like are well known. Virgin aggregate is utilized, which is largely comprised of crushed rock, small rock, and sand generally one inch in diameter and down to a sieve size of 200. Three quarter inch in diameter is often preferable. Typically, virgin aggregate is heated between 220° and 350° F. and dried in a rotating drum. Asphalt or asphalt-concrete oil is utilized with various penetration numbers ranging from 85 to 150, and which is also heated to a range of 280° to 350° F. The heated aggregate is then mixed with liquid asphalt in a proportion typically of five to six percent asphalt by weight. The paving composition is then hauled with trucks to the job site and dumped into a paving vehicle. The paver lays the hot mix out level to a desired thickness on top of a graded gravel surface of a suitable elevation and smoothness. Thereafter the new pavement is compacted with a roller to the desired density.
Commercial asphalt paving composition plants have a variety of problems. Asphalt plants are complex in that they require scales, tumble dryers, conveyors, furnaces, mixers, huge tanks for heating oil and asphalt oil and complex pollution control systems for controlling dust and emissions. Consequently, asphalt plants are stationary and not easily movable.
Roofing materials, including shingles, tar paper and portions thereof, also utilize asphalt. The asphalt is commonly an asphalt-concrete oil (AC Oil) which is heavy and tar-like.
FIG. 1
schematically shows in cross section the composition of shingles
10
. Shingles
10
begin with a mat
12
which may either be fiberglass or of a paper felt-like material. Initially the mat
12
is soaked with a light saturine oil
14
. Thereafter, a layer of asphalt-concrete oil
16
is applied thereto. Next a layer of lime dust
18
is placed or dusted thereon. Another layer of AC Oil
20
is applied after which a rock layer
22
is applied. Thereafter, the entire composition is run through rollers.
Considerable roof waste (RARW—Recycled Asphalt Roofing Waste) is associated with the manufacture of new shingles, which may approximate one hundred million squares annually. A square is one hundred square feet of shingles. Each shingle has three tabs cut out. Each cutout tab measures one-quarter inch by five inches. The three discarded tabs represent approximately two and a half percent of each new shingle which is discarded. When old shingles and tar paper are removed from old construction, the one to three layers of shingles are all considered waste and are to be disposed of. Thus old shingle materials, also RARW, represent an even larger amount of waste associated with shingle materials.
Methods and apparati have been disclosed by which old shingles and shingle material have been attempted to be recycled, such as those shown in U.S. Pat. Nos. 4,222,851; 4,706,893; 4,726,846; 5,201,472; 5,217,530; and 5,236,497. Illustratively, the '893 patent shows a method and apparatus wherein recycled shingles may be used in an asphalt plant mixed with heated and dried aggregate and liquid asphalt to form an asphalt paving composition. However, these prior methods of creating pavements and apparati have not been commercially successful for various reasons and especially due to their inability to create an acceptable pavement composition and to handle shingles without clogging or plugging up apparati.
More specifically, shingle materials by their very nature pose a complex problem in their reduction for recycling. The shingle materials, including the rock and asphalt oil in a range of twenty to thirty percent, are extremely heavy, sticky and abrasive. Efforts to reduce the shingle materials to particles and granules in hammermills have met with the clogging, plugging and sticking of the particles and granules within the hammermill, shutting down the production and necessitating maintenance and cleaning. Consequently, no one has reduced shingle materials to a small enough size that will permit their use alone or within an asphalt plant.
Prior art pavements utilizing RARW or Recycled Asphalt Roofing Waste are plagued with the two basic problems of air voids and stabilization. Air voids generally may be thought of as air pockets in the pavement. The air pockets must not be too tight or there will not be enough room to allow the pavement to move or slightly expand during freezing. If the air voids or air pockets are too loose, the pavement will be highly susceptible to water. Applicant has found that air voids in the range of two to eight percent are ideal and the prior art mixtures have had problems in attaining this acceptable range.
With respect to stabilization or firmness of the pavement material, the pavement material must not be too firm or it will not be workable in application as a pavement. Conversely, the material must have some degree of firmness or it will not set up for traffic use and will result in rutting. Applicant has found that a stabilimeter value of 800 to 3000 is acceptable and the prior art pavement mixtures and materials have had difficulty in consistently reaching this range.
The reason for the prior art mixtures and pavement materials' failure to meet acceptable ranges of air void and stabilization values is largely due to the many variables in making an acceptable paving composition with recycled roofing waste. The aggregate utilized is of a range of size from one inch to two hundred sieve size. The aggregate's porosity may also vary greatly. Furthermore, the aggregate may carry water for a significant amount of moisture into the mixture which causes problems. The condition of the RARW or shingle materials greatly affects the mixture. Older shingle materials commonly are oxidized and may have a significantly reduced AC oil content. Also, shingle materials may carry moisture, which also poses the problem described above. Some of these problems may be solved by conceivably superheating the mixture. However, equipment for superheating the mixture to a high enough temperature is not available at this time.
There is a need for a method of manufacturing and applying a new pavement and patch composition material for roadways, driveways, walkways, patches for potholes and cracks and the like wherein the composition may include recycled roofing waste (RARW), aggregate, rejuvenating oil, recycled asphalt pavement (RAP), RARW and RAP (RAM—Recycled Asphalt Mixture), and other reduced solid materials, emulsifiers, liquid silicone and anti-strip additives that have acceptable air voids and stabilization values without the need for a complex and polluting asphalt plant.
REFERENCES:
patent: 4236675 (1980-12-01), Bladykas
patent: 4238241 (1980-12-01), Schneider
patent: 4706893 (1987-11-01), Brock
patent: 5017230 (1991-05-01), Hopkins et al.
patent: 5201472 (1993-04-01), Brock
patent: 5217530 (1993-06-01), Grzybowski
patent: 5223032 (1993-06-01), Gaudio et al.
patent: 5236497 (1993-08-01), Grzybowski
patent: 5340391 (1994-08-01), Grzybowski
patent: 5344485 (1994-09-01), Glynn, Jr.
patent: 5348418 (1994-09-01), Campbell
patent: 5511899 (1996-04-01), Pavelek, II
Helget Gerald E.
Lisehora James A.
Rider Bennett Egan & Arundel
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