Patent Abstract:
The present invention includes a system for recycling pavement constituents in situ. A vehicle for traversing the pavement constituents comprising a container for storing and preserving heated pavement rejuvenation materials and at least one heating element adapted to heat the pavement rejuvenation materials above their working temperature. A dispensing element is in communication with the container for dispensing the pavement rejuvenation materials to the pavement constituents. The vehicle also supports at least one mixing element which is adapted to mix in situ the pavement constituents and the heated pavement rejuvenation materials together in such a manner that the pavement constituents are raised to a working temperature. The system also comprises a compaction element for compacting the pavement constituents.

Full Description:
RELATED APPLICATIONS  
       [0001]     This Patent application is a continuation-in-part of U.S. patent application Ser. No. 11/070,411 filed on Mar. 1, 2005 and entitled Apparatus, System, and Method for Directional Degradation of a Paved Surface, which is herein incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to road resurfacing equipment and more particularly to apparatus, systems and methods for recycling a paved surface in situ.  
         [0004]     2. Background  
         [0005]     Asphalt is the most recycled material in the United States. In fact, more than 73 million tons of asphalt pavement removed each year during highway widening and resurfacing projects is reused as pavement. Such recycling efforts conserve natural resources, decrease construction time, minimize the impact of asphalt plant operations on the environment, and reduce reliance on landfills. Further, research shows that the structural performance of mixtures integrating reclaimed asphalt pavement (“RAP”) is equal to, and in some instances better than, virgin asphalt pavement.  
         [0006]     A process for recycling a paved surface may include mechanically breaking up a paved surface, applying fresh asphalt or asphalt rejuvenation materials to the broken pieces, depositing the mixture over the road surface, and compacting the mixture to restore a smooth paved surface. In some cases, broken asphalt may be removed from a road surface, treated off location, and then returned and compacted. By enabling the majority of road surface excavation and renovation to occur through a continuous operation in situ, road recycling processes reduce manpower, time and resources required with conventional road resurfacing techniques.  
         [0007]     In some cases, a paved surface may be pre-heated to facilitate pavement removal as well as to increase thermal bonding between new and reclaimed pavement constituents. The low heat conductivity of asphalt and its susceptibility to damage from scorching or overheating, however, creates a dilemma in pavement recycling. In some cases, intense heat must be applied to bring the full depth of the pavement to a workable temperature while the pavement surface must be protected from scorching or overheating.  
         [0008]     To overcome this problem, many conventional road recycling processes require heating equipment to make several passes over the same section of roadway in order to heat and work the pavement to a sufficient depth. This procedure is inefficient, time-consuming, and results in most of the heat being concentrated at the pavement surface, as opposed to a uniform distribution through the full depth of the paved surface. Other road recycling processes use multiple heating units that each operate at a temperature below the asphalt burning point. A large number of such units are required to achieve the desired heat penetration, thereby increasing the amount and cost of recycling equipment needed to repair a paved surface  
         [0009]     Accordingly, what are needed are improved apparatus, systems, and methods for in situ pavement recycling. More particularly, apparatus, systems, and methods are needed allowing application of higher temperatures to a paved surface in situ, while providing more uniform heat distribution and a reduced likelihood of burning, scorching, or other damage. Beneficially, such a system would improve the bond between new and recycled pavement constituents, reduce the amount of new pavement materials needed to rejuvenate a paved surface, facilitate immediate pavement finishing processes, and increase the structural integrity of the resulting recycled paved surface. Such apparatus, systems, and methods are disclosed and claimed herein.  
       SUMMARY OF THE INVENTION  
       [0010]     Consistent with the foregoing, and in accordance with the invention as embodied and broadly described herein, a system for recycling pavement constituents in situ is disclosed. A vehicle for traversing the pavement constituents has a container for storing heated pavement rejuvenation materials and there is at least one heating element adapted to heat the pavement rejuvenation materials within the container. A dispensing element is in communication with the container for dispensing the pavement rejuvenation materials to the pavement constituents on a road bed. The vehicle also supports at least one mixing element which is adapted to mix in situ the pavement constituents and the heated pavement rejuvenation materials together in such a manner that the pavement constituents are raised to a working temperature. The system also comprises a compacting element for compacting the resulting mixture of pavement constituents and pavement rejuvenation materials into a new road surface.  
         [0011]     In certain aspects of the present invention the at least one mixing element rotates on an axis normal to a road bed. The mixing element may be further adapted for independent movement to avoid obstacles on the road bed, such as manholes, tracks, utilities, and curbs. The mixing element may be adapted to move independently of other mixing elements also supported by the vehicle in a vertical direction, horizontal direction, circular direction, and/or an angular direction. The mixing element may be supported by the vehicle in a reducing environment, which is adapted to prevent oxidation of the pavement constituents and/or the pavement rejuvenation materials. The reducing environment may further comprise a reduction source selected from the group consisting of an exhaust gas, a rich-burning flame, or a reducing gas. Mixing elements may be selected from the group consisting of mills, degradation elements, screeds, rakes, tongs, or drums.  
         [0012]     The dispensing element may be formed in the mixing element. At least a second dispensing element may be in communication with a supply selected from the group consisting of water, polymers, surfactant, and combinations thereof. The second dispensing element may be adapted to dispense the supply into the pavement constituents.  
         [0013]     The vehicle may also support at least one degradation element adapted to degrade a paved surface into pavement constituents. The at least one degradation element may be spaced within a predetermined distance from the mixing element wherein the predetermined distance controls the maximum size of the pavement constituents.  
         [0014]     The container on the vehicle may be adapted to store the heated pavement rejuvenated materials in a reducing environment. The heating elements adapted to heat the pavement rejuvenation materials may be selected from the group consisting of radiant heaters, hot air heaters, convection heaters, microwave heaters, direct flame heaters, and combinations thereof. The vehicle may also support at least another heating element, which may be selected from the same group, to aid in heating the pavement constituents to a working temperature. The working temperature may be between 200° F. to 1100° F., an ideal working temperature may depend on the type and size of the pavement constituents as well as other factures like climate.  
         [0015]     In another aspect of the present invention a method includes recycling pavement in situ. The method comprises the steps of degrading a paved surface to produce pavement constituents; heating the constituents to a working temperature by simultaneously dispensing heated pavement rejuvenation materials and mixing the pavement constituents with the heated pavement rejuvenation material; and compacting the resulting mixture of pavement constituents and pavement rejuvenation materials into a new road surface.  
         [0016]     The mixing may be accomplished by a plurality of mixing elements adapted to rotate on an axis normal to a road bed. The maximum constituents size may be controlled by the distance between the plurality of mixing element and a plurality of degradation elements. The heated pavement rejuvenation materials may be stored in a reducing environment before they are dispensed and mixed with the pavement constituents. The heating may be performed in a reducing environment. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     In order that the manner in which the above recited and other features and advantages of the present invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that the drawings depict only typical embodiments of the present invention and are not, therefore, to be considered as limiting the scope of the invention, the present invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:  
         [0018]      FIG. 1  is a perspective view of one embodiment of an apparatus for recycling pavement in situ in accordance with the present invention;  
         [0019]      FIG. 2  is a perspective view of one embodiment of an apparatus for recycling pavement in situ, with the outer shroud removed;  
         [0020]      FIG. 3  is a side view of one embodiment an assembly comprising a mixing and heating mechanism in accordance with the invention;  
         [0021]      FIG. 4  is a side view of another embodiment of an assembly comprising a mixing and heating mechanism in accordance with the invention;  
         [0022]      FIG. 5  is a side view of another embodiment of an apparatus for recycling pavement in situ;  
         [0023]      FIG. 6  is a perspective view of an embodiment of a plurality of mixing elements;  
         [0024]      FIG. 7  is a bottom view of an embodiment of degradation and mixing elements;  
         [0025]      FIG. 8  is a bottom perspective view of another embodiment of an apparatus for mixing and heating pavement materials in situ;  
         [0026]      FIG. 9  is a side perspective view of the mixing and heating mechanisms illustrated with the apparatus of  FIG. 5 ;  
         [0027]      FIG. 10  is a side perspective view of one embodiment of an apparatus comprising a reduction chamber surrounding the heating and mixing elements;  
         [0028]      FIG. 11  is a perspective view illustrating mixing elements that may be elevated to avoid obstacles in the roadway;  
         [0029]      FIGS. 12 through 18  illustrate various embodiments of mixing elements in accordance with the invention; and  
         [0030]      FIG. 19  is a flow diagram of one embodiment of a process for recycling a paved surface in situ. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment in accordance with the present invention. Thus, use of the phrase “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but does not necessarily, all refer to the same embodiment.  
         [0032]     Furthermore, the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.  
         [0033]     In the following description, numerous specific details are disclosed to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.  
         [0034]     In this application, “pavement” or a “paved surface” refers to any artificial, wear-resistant surface that facilitates vehicular, pedestrian, or other form of traffic. Pavement may include composites containing oil, tar, tarmac, macadam, tarmacadam, asphalt, asphaltum, pitch, bitumen, minerals, rocks, pebbles, gravel, sand, polyester fibers, Portland cement, petrochemical binders, or the like. The term “degrade” is used in this application to mean milling, grinding, cutting, ripping apart, tearing apart, or otherwise taking or pulling apart a pavement material into smaller constituent pieces. Similarly, the term “pavement constituents” is used to mean any materials or components used to create a paved surface, including new or reclaimed materials, or combinations thereof.  
         [0035]     Referring to  FIG. 1 , one contemplated embodiment of an apparatus  100  for use in pavement recycling applications is illustrated. In general, an apparatus  100  may include a frame  102 , a shroud  104  or cover  104  enclosing various internal component of the apparatus  100 , and a translation mechanism  106 , such as tracks, wheels, or the like, to translate the apparatus  100  along a surface. The translation mechanism  106  may include several sets of tracks, for example, which may be vertically adjusted with respect to the frame  102  to adjust the slant or elevation of the apparatus  100 , and to adjust for varying elevations, slopes, and contours of the underlying road surface.  
         [0036]     The apparatus  100  may include one or more heating and mixing assemblies  108   a ,  108   b  as will be described with additional specificity with respect to  FIGS. 3 and 4 , which may be used to simultaneously heat and mix pavement constituents  105  for compaction into a new or recycled road surface  109 . In selected embodiments, a first heating and mixing assembly  108   a  may be extended and retracted with respect to one side of the apparatus  100  and a second heating and mixing assembly  108   b  may be extended and retracted with respect to a second side of the apparatus  100 , thereby allowing the heating and mixing assemblies  108   a ,  108   b  to sweep over an area significantly wider than the apparatus  100 . In selected embodiments, the width of each heating and mixing assembly  108   a ,  108   b  may approximate the width of the apparatus  100 . In such embodiments, the assemblies  108   a ,  108   b  may sweep over a road width that is approximately twice the apparatus width when the assemblies  108   a ,  108   b  are fully extended from each side of the apparatus  100 . The extension and retraction of the assemblies  108   a ,  108   b  will become more readily apparent from the description of  FIG. 5 .  
         [0037]     As will become more apparent from the description of  FIGS. 3 and 4 , the heating and mixing assemblies  108   a ,  108   b  may include a variety of elements to process and manipulate the pavement constituents  105 . For example, these elements may include mixing elements to mix the pavement constituents  105 , heating mechanisms to apply heat to the pavement constituents  105  as they are mixed by the mixing elements, and dispensing elements to dispense a supply of water, surfactant, polymers, and/or new pavement materials to mix with the pavement constituents  105  extracted from the road surface  107 . In selected embodiments, the heating and mixing assemblies  108   a ,  108   b  may optionally include degradation elements to degrade an existing paved surface  107  into smaller fragments or constituent pieces  105 . One of ordinary skill in the art will recognize, however, that in other embodiments, the heating and mixing assemblies  108   a ,  108   b  may be used to process and manipulate pavement fragments or constituents  105  previously generated by other road reconstruction equipment. In such embodiments, the apparatus  100  may not include degradation elements.  
         [0038]     The apparatus  100  may include one or more compaction elements  110   a ,  110   b , such as rollers, screeds, or tampers. These compaction elements  110   a ,  110   b  may be used to compact and smooth the mixture of pavement constituents  105  produced by the mixing and heating assemblies  108   a ,  108   b . Like the heating and mixing assemblies  108   a ,  108   b , the compaction elements  110   a ,  110   b  may be extended and retracted with respect to each side of the apparatus  100  to allow the compaction elements  110   a ,  110   b  to compact or smooth a surface wider than the apparatus  100 . In selected embodiments, the compaction elements  110   a ,  110   b  may be extended and retracted to reflect the position of the heating and mixing assemblies  108   a ,  108   b . Both the heating and mixing assemblies  108   a ,  108   b  and the compaction elements  110   a ,  110   b  may include extension and retraction mechanisms  112  such as tracks, hydraulic or pneumatic cylinders, or other mechanisms known to those skilled in the art, to extend and retract the assemblies  108   a ,  108   b  and the compaction elements  110   a ,  110   b  with respect to the apparatus  100 . In some embodiments, the compaction element may also be heated.  
         [0039]     Referring to  FIG. 2 , under the shroud  104 , the apparatus  100  may include a variety of components to perform various features and functions. For example, in certain embodiments, the apparatus  100  may include an engine  114 , such as a diesel or gasoline engine, to power the apparatus  100 . The engine  114  may receive fuel from a fuel tank  116 . In certain embodiments, the engine  114  may be used to drive one or more hydraulic pumps  118  which may drive hydraulic motors (not shown) for powering the translation mechanism  106 . The hydraulic pumps  118  may also be used to drive one or more hydraulic cylinders  120 , connected to the translation mechanism  106 , for adjusting the level, slant, or elevation of the apparatus  100 , or to compensate for variations in elevation and slope of the underlying road surface. The hydraulic pumps  118  may also be used to power the extension and retraction mechanisms  112  connected to the heating and mixing assemblies  108   a ,  108   b  and the compaction elements  110   a ,  110   b . Additionally, the hydraulic pumps  118  may be used to power the mixing, dispensing, and degradation elements, as will be described with respect to  FIGS. 3 and 4 .  
         [0040]     In selected embodiments, the apparatus  100  may include an air compressor  122  to provide pneumatic power or an air supply to the apparatus  100 . Similarly, the apparatus  100  may include one or more tanks  124  to store hydraulic fluid and additional hydraulic pumps  126  which may be used to supplement the hydraulic pumps  118  powered by the engine  114 . In certain embodiments, the apparatus  100  may include a computer or other electronic equipment  128  to control the apparatus  100 , and to communicate with various remote sources, including but not limited to radio, satellite, cellular, Internet, or other sources. In selected embodiments, the computer and electronic equipment  128  may communicate wirelessly with these remote sources by way of one or more antennas  130 . Such a system may permit the apparatus  100  to be controlled or monitored remotely, or allow data to be uploaded or downloaded to the apparatus  100 , as needed. The apparatus  100  may also take advantage of various control systems used in modern asphalt mills, grinders, and cutters, to provide manual or automated control of the apparatus  100 , including but not limited to elevation, speed, steering, cut depth, and leveling controls. These controls may employ various feedback systems and sensors located at a variety of locations around the apparatus  100 .  
         [0041]     The apparatus  100  may also include at least one container such as a hopper  132  and/or a tank  134 . The containers may store rejuvenation or renewal materials that may be mixed with pavement constituents on the road bed  107 . The resulting mixture may then be applied to the road bed to create a recycled surface  109 . Rejuvenation or renewal materials that may be stored in the hopper  132 , tank  134 , or both, to be used in a recycling process may include, for example, oil, tar, tarmac, macadam, tarmacadam, asphalt, asphaltum, pitch, bitumen, minerals, rocks, pebbles, gravel, sand, polyester fibers, Portland cement, petrochemical binders. Electronic  241  may control a heating element internal to the tank  134  and/or hopper  132  for heating the pavement rejuvenation material. In some embodiments a surfactant may be added with the rejuvenation or renewal materials. It is believed that the surfactant may help reduce the surface tension of oils and help promote mixing. Other rejuvenation materials or renewal materials may foam, which may also aid in pavement recycling process. In selected embodiments, the hopper  132  may be used to store dry materials, such as rocks and gravel, and the tank  134  may be used to store liquids, such as oil or tar.  
         [0042]     Referring to  FIG. 3 , one contemplated embodiment of a heating and mixing assembly  108  is illustrated. Various details, such as the extension and retraction mechanisms  112  illustrated in  FIGS. 1 and 2 , have been omitted in this example for sake of simplicity. As illustrated, a heating and mixing assembly  108  in accordance with the invention may include a heating mechanism  136  and one or more mixing elements  138   a - c . The heating mechanism  136  may be positioned substantially above or adjacent to the mixing elements  138   a - c  in order to apply heat to the pavement constituents  105  as they are mixed by the mixing elements  138   a - c . By heating and mixing the pavement constituents  105  simultaneously, much higher temperatures may be applied to the to pavement constituents  105  without burning, damaging, or destroying asphalt, tar, oil, or other heat-sensitive materials in the pavement. This is because the mixing elements  138   a - c  circulate the pavement constituents such that high temperatures are not directly concentrated on any specific portion of the pavement constituents  105  for more than a brief period of time. As a result, the pavement constituents  105  may be heated more rapidly and uniformly.  
         [0043]     The mixing elements  138   a - c  may be adapted to circulate the pavement constituents  105  vertically, horizontally, or a combination thereof, with respect to the road surface. For example, selected mixing elements  138   a ,  138   b  may be adapted to vertically circulate the pavement constituents between the underlying road bed and the surface. In this example, the helical vanes of the mixing elements  138   a ,  138   b  may be used to circulate the pavement constituents in a substantially vertical direction. In other embodiments, a mixing element  138   c  may be used to circulate pavement constituents  105  in a substantially horizontal direction. Here, the curved shaped of the mixing element  138   c  may be used to stir the pavement constituents  105  primarily in the horizontal plane parallel to the road surface. By mixing the pavement constituents  105  both vertically and horizontally, the mixing elements  138   a - c  disperse the heat uniformly through the pavement constituents  105 , thereby preventing burning, scorching, or damage thereto.  
         [0044]     As mentioned, the ability to apply higher temperatures to the pavement constituents  105  allows more rapid heating of the pavement constituents  105  and allows use of higher temperature heating mechanisms  136 . In this example, the heating mechanism  136  is a tubular radiant heater. Nevertheless, any suitable heater may be used to heat the pavement constituents  105  while mixing, including but not limited to a hot air heater, a convection heater, a microwave heater, or a direct flame heater. Although not illustrated in this example, the heating mechanism  136  may also incorporate a blower, or vents, to more effectively direct the heat toward the pavement constituents  105 .  
         [0045]     The preferred heating mechanism may also comprise the hot pavement rejuvenation material. In this embodiment the pavement rejuvenation material may be preheated before it is dispensed onto the road bed, which may be done in a reducing environment. It is believed that if the hot pavement rejuvenation material is heated to 2000° F. (this may be accomplished in the reducing environment without combustion in either the tank  132  or hopper  134 ) and then is added to the road bed to constitute 10 percent of the aggregate and the pavement constituents are about 50° F. and constitutes 90 percent of the aggregate then the overall temperature of the mixed aggregate will be about 245° F. One of ordinary skill in the art would recognize how to adjust the temperatures and ratios to achieve their desired temperature. It is believed that for an embodiment as described in this paragraph, an ideal temperature would be within a range of 200° F. to 400° F.  
         [0046]     Mixing also allows higher temperatures since the heat will not be focused on just pavement constituents closest to the heating mechanism, but the heat will be more evenly distributed throughout all of the pavement constituents and the pavement rejuvenation materials.  
         [0047]     The heating and mixing assembly  108  may also include a dispensing element  140  to provide a supply of new pavement materials  142 , such as rocks, gravel, or sand to mix with the pavement constituents  105  extracted from the existing road surface  107 . In selected embodiments, a mixing element  138   c  may also function as a dispensing element. For example, a mixing element  138   c  may include a central bore  144  for dispensing a material  146  such as oil, tar, asphalt, or the like for mixing with the pavement constituents  105 . The dispensing elements  140 ,  138   c  may communicate with a remote supply of new pavement materials, such as those stored in the hopper  132  or tank  134  as discussed with respect to  FIG. 2 . In selected embodiments, new pavement materials  142 ,  146  provided by the dispensing elements  140 ,  138   c  may be pre-heated prior to addition to the existing constituents  105 . This may aid in heating the resulting mixture and may provide improved bonding. Once the newer materials  142 ,  146  are mixed with those extracted from the road surface  107 , the resulting mixture may be compacted into a new or recycled surface  109  by the compaction element  110 . In other embodiments, as shown in  FIG. 5 , the dispensing element  140  is attached to the vehicle and directs the new pavement materials  142 , water, surfactant, and/or polymers to the degradations element  147  and/or the mixing element.  
         [0048]     As mentioned, in selected embodiments the heating and mixing assembly  108  may include degradation elements  147  to degrade the paved surface  107 . One type of degradation element  147  that may be suitable for use with the present invention is described in U.S. patent application Ser. No. 11/070,411 and entitled “Apparatus, System, and Method for Directional Degradation of a Paved Surface,” having common inventors with the present invention, to which this application claims priority and incorporates by reference in its entirety. In this example, the degradation element  147  rotates about an axis substantially normal to the road surface. As the apparatus  100  moves forward, the degradation element  147  cuts or tears into the paved surface  107  using a motion similar to that of a router bit cutting into a wood surface. Nevertheless, one of ordinary skill in the art will recognize that the heating and mixing elements  136 ,  138   a - c  may function with other types of road cutting and milling equipment, including convention cutting drums rotating about an axis substantially parallel to the road surface. Thus, any type of cutting, milling, or degrading element  147  is within the scope of the present invention.  
         [0049]     In certain embodiments, a skirt  149  may be used to surround the heating and mixing elements  136 ,  138   a - c , thereby creating a high-temperature or reduction chamber  151 . The skirt  149  may be used to retain and focus the heat produced by the heating mechanism  136  on the pavement constituents  105 , in addition to reducing dust or other particulates produced from the heating and mixing process. In selected embodiments, an oxidation-depleted (i.e., reducing) gas may also be introduced inside the skirt  149  to reduce the oxidation of the pavement constituents  105 , thereby promoting improved bonding between the new pavement materials  142 ,  146  and materials recycled from the road surface  107 . This concept will be described in additional detail in the description associated with  FIG. 7 .  
         [0050]     Referring to  FIG. 4 , in another contemplated embodiment in accordance with the invention, a heating and mixing assembly  108  may include heating mechanisms  136   a - b , such as a microwave heater  136   a , a radiant heater  136   b , or the like. A first mixing element  138   a  may be effective to circulate the pavement constituents  105  substantially vertically while a second mixing element  138   c  may be effective to stir the pavement constituents  105  substantially horizontally with respect to the paved surface. The second mixing element  138   c  may also include a central bore  144  for dispensing a supply of pavement rejuvenation materials  146 , such as tar, oil, or asphaltum. This mixing element  138   c  may reach a depth sufficient to deposit the rejuvenation materials  146  at or near the road bed  148  to promote thorough mixing with the pavement constituents  105  and effective bonding between the recycled surface and the underlying road bed  148 . Another dispensing element  140  may be used to supply a quantity of new pavement materials  142 , such as rock, gravel, sand to the mixture  105 .  
         [0051]     Referring to  FIG. 5 , another embodiment of the present invention is shown. A dispensing element  240  directs pavement rejuvenated material  142  to the degradation elements  147 . The rejuvenated materials  142  are mixed immediately into the pavement constituents  105  as the degradation elements  147  degrade the paved surface  107 . It is believed that such an embodiment effectively wets at least a majority of the pavement constituent&#39;s surface areas. Another dispensing element  140  adds hot pavement constituents to the pavement constituents  105  already residing in the road bed. A plurality of mixing elements  138  follow the degradation elements  147 , allowing the heat from the added pavement constituents and pavement rejuvenated materials to be spread evenly throughout the aggregate.  
         [0052]      FIG. 6  shows an embodiment of a plurality of mixing elements  138  shown detached from the vehicle for clarity. Each mixing element  138  comprises a shaft  201  with a dispensing port  200  located through its center. The dispensing ports  200 , may also add rejuvenated materials or new pavement constituents. It may be desirable to dispense hot oil or other pavement rejuvenated materials from the dispensing ports  200  directly on the road bed to promote bonding between the road bed and the pavement constituents  105 .  
         [0053]      FIG. 7  shows an embodiment of the degradation element  147  and a plurality of mixing elements  138 . In some embodiments of the present invention, the degradation elements  147  are separated by a predetermined distance  202  to control the maximum size a pavement constituent may be. It may be preferable to have the maximum constituent size be ½ inch; in such an embodiment, the degradation elements  147  may be spaced substantially ½ inch apart. Further the mixing element would also need to be spaced ½ apart to allow the maximum constituent size to the pass between them. In accordance with the same embodiment, it may also be desirable to have the mixing elements  138  spaced ½ inch from the degradation element  147 ; allowing pavement constituents larger than ½ inch to be forced back to the degradation elements  147 . The plurality of mixing elements  138  may be stationary, or that may move in a vertical direction, horizontal direction, circular direction, and/or angular direction with respect to the vehicle. It would be obvious to one of ordinary skill in the art to adjust the predetermined distance  202  to achieve a different constituent size. It would also be obvious to one of ordinary skill in the art to modify the cutting depth, the rpm and/or size of the degradation element  147  and/or mixing element  138  to achieve other maximum constituent sizes and/or the distribution of constituent sizes.  
         [0054]     Referring to  FIGS. 8 and 9 , another contemplated embodiment of an apparatus  100 , comprising heating and mixing assemblies  108   a ,  108   b , is illustrated. In this embodiment, a first heating and mixing assembly  108   a  may be extended with respect to a first side  156  of the apparatus  100 , and a second heating and mixing assembly  108   b  may be extended with respect to a second side  158  of the apparatus  100 , thereby enabling the heating and mixing assemblies  108   a ,  108   b  to traverse a pavement area significantly wider than the apparatus  100 .  
         [0055]     The heating and mixing assemblies  108   a ,  108   b  may include various mixing elements  138   d  to circulate the pavement constituents  105  primarily horizontally with respect to the pavement surface. These mixing elements  138   d  may include agitation members  150  to circulate the pavement constituents  105  substantially horizontally as the mixing elements  138   d  rotate. Other mixing elements  138   e  may circulate the pavement constituents primarily vertically with respect to the pavement surface. These mixing elements  138   e  may, in certain embodiments, include spiral or helical agitation members  152  around the perimeter thereof to circulate the pavement constituents  105  substantially vertically as the mixing elements  138   e  rotate. One of ordinary skill in the art will recognize that by adjusting the angle of the agitation members  150 ,  152 , the mixing elements  138   d ,  138   e  may, in some cases, be adapted to circulate the pavement constituents  105  both horizontally and vertically with respect to the pavement surface. In certain embodiments, the mixing elements  138   d ,  138   e  may include a central bore  154  or other channel  154  for supplying rejuvenation materials to the pavement constituents  105 .  
         [0056]     A radiant heater  136  may be mounted immediately above or proximate the mixing elements  138   d ,  138   e  to heat the pavement constituents  105 , including old and new pavement materials, as the mixing elements  138   d ,  138   e  circulate the pavement constituents  105 . A radiant heater  136  may, for example, comprise a tubular structure to circulate hot water, steam, or other heated gases or liquids. Once the pavement constituents  105  are heated, mixed, and rejuvenation materials are added, the resulting mixture may be compacted by compaction elements  110   a ,  110   b , such as rollers, tampers or screeds. The compaction elements  110   a ,  110   b , like the heating and mixing assemblies  108   a ,  108   b , may be extended from each side  156 ,  158  of the apparatus  100  to follow the heating and mixing assemblies  108   a ,  108   b.    
         [0057]     Referring to  FIG. 10 , in selected embodiments, an apparatus  100  in accordance with the invention may include a skirt  149  to create a high-temperature or reduction chamber  151 . The skirt  149  may surround the heating and mixing elements  136 ,  138   a - c  and may aid in heating the pavement constituents  105  by retaining or focusing heat inside the skirt  149 . In selected embodiments, the skirt  149  may be in communication with an oxygen-depleted gas source  160  which may include, for example, an exhaust source such as a fuel-rich exhaust source, or a flame such as a fuel-rich flame. An oxygen-depleted gas may also be directed to the containers shown in  FIG. 2 , in order to heat the pavement rejuvenation materials to higher temperatures than would otherwise be allowed.  
         [0058]     Still referring to  FIG. 10 , in certain embodiments, exhaust  160  produced by the apparatus  100  may be directed into the chamber  151  to create an oxygen-depleted or reducing atmosphere. This atmosphere may aid in reducing the oxidation of pavement constituents  105  which may serve to create a stronger chemical bond between new and old pavement constituents  105 . The oxygen-depleted atmosphere may also reduce the likelihood of combustion or fire within the chamber  151 , which may, in turn, enable the application of significantly higher temperatures to the pavement constituents  105 . In other embodiments, gases directed into the chamber  151  may also aid in heating the pavement constituents  105 . Although illustrated as a fabric-like material, the skirt  149  may be also be embodied as a brush, bellow, or one or more metal or non-metal panels, as illustrated in  FIGS. 1 and 2 .  
         [0059]     As degradation elements  147  degrade a worn paved surface  107 , oxygen may bind to the surface of the pavement constituents  105  and interfere with pavement constituents  105  binding to other each other or to pavement rejuvenation materials  142 . It will be advantageous to mix the pavement constituents  105  within the reduction chamber  151 , so that all of the pavement constituent surfaces become exposed to the reducing environment within the reduction chamber  151  and become reduced.  
         [0060]     Referring to  FIG. 11 , in selected embodiments, mixing elements  138   d - e  of a heating and mixing assembly  108  may be independently elevated with respect to the road bed  148  or surface  148 . Thus, the mixing elements  138   d - e  may be elevated to avoid structures such as manholes  162 , culverts, or utility lines. For example, one or more mixing elements  138   d  may be elevated to avoid a manhole  162  while others  138   e  may be extended to mix the pavement constituents  105 . The mixing elements  138   d - e  may be actuated by hydraulic, pneumatic, or other mechanical means known to those of skill in the art. Similarly, the elevation of the mixing elements  138   d - e  may be controlled manually, such as by an operator, or automatically using sensors and/or feedback systems.  
         [0061]     Referring generally to  FIGS. 12 through 18 , various embodiments of mixing elements  138  for agitating or circulating the pavement constituents  105  are illustrated. Each of these embodiments may agitate, mix, blend, or circulate the pavement constituents  105  in a unique manner and direction, and each may be suitable for use in various different embodiments of the present invention. For example, referring to  FIG. 12 , in certain embodiments a mixing element  138  may include a rotating shaft  164  comprising one or more agitation members  166  protruding therefrom. The shaft  164  may rotate about an axis substantially normal to the surface of the road. Likewise, the agitation members  166  may travel within a plane substantially parallel to the road surface, thereby circulating the pavement constituents substantially parallel to the road surface.  
         [0062]     Referring to  FIG. 13 , in another embodiment, a mixing element  138  may comprise a shaft  164  rotating about an axis substantially parallel to the road surface. In this embodiment, a rigid helix  168  or spiral  168  may be attached to the shaft  164  to circulate pavement constituents  105  in a direction substantially parallel to the shaft  164 . Thus, the pavement constituents  105  may circulate in a direction substantially parallel to the road surface. Alternatively, the shaft  164  might include agitation members  166 , like those illustrated with respect to  FIG. 12 , which would circulate the pavement constituents  105  in a direction both perpendicular and parallel to the road surface. In certain embodiments, the shaft  164  may connect to and rotate with respect to one or more arms  170  extending from the apparatus  100  or heating and mixing assembly  108 .  
         [0063]     Referring to  FIG. 14 , in another contemplated embodiment, a mixing element  138  may include a shaft  164  and a helical member  172  attached thereto. The helical member  172  may optionally have a conical shape. As the shaft  164  rotates, the helical member  172  may circulate the pavement constituents  105  in direction both perpendicular and parallel to the road surface.  
         [0064]     Referring to  FIG. 15 , in another embodiment, a mixing element  138  may include one or more paddles  174  extending from a shaft  164 . The paddles  174  may be flat or curved to circulate the pavement constituents  105  as the shaft  164  rotates. By adjusting the curvature, pitch, or shape of the paddles  174 , the paddles  174  may be adapted to circulate the pavement constituents in a direction both perpendicular and parallel to the road surface. In certain embodiments, as illustrated by  FIG. 13 , an opening  176  may be formed in the paddles  174  to improve or otherwise alter the mixing characteristics of the mixing element  138 .  
         [0065]     Referring to  FIG. 17 , in selected embodiments, a mixing element  138  may include one or more members  178  or paddles  178  that rotate about an axis substantially parallel to the road surface. Such an embodiment may be effective to mix or agitate the pavement constituents  105  in a direction both perpendicular and parallel to the road surface.  
         [0066]     Referring to  FIG. 18 , in yet another embodiment, a mixing element  138  may include a shaft  164  and a member  180  offset from the shaft  164 . Due to the offset, the member  180  may take a substantially circular path  182  as the shaft  164  rotates, thereby mixing and agitating the pavement constituents  105 .  
         [0067]     Referring to  FIG. 19 , a method for recycling a paved surface in situ in accordance with the present invention may include first degrading  186  a paved surface to produce degraded pavement constituents, heating and mixing  190  the degraded pavement constituents substantially simultaneously in situ to promote thermal bonding therebetween, and compacting  194  the degraded pavement constituents to provide a recycled paved surface. In some embodiments, a method in accordance with the present invention may further comprise pre-heating  184  the paved surface to soften the pavement prior to degradation.  
         [0068]     A method for recycling a paved surface in situ may further comprise isolating  188  degraded pavement constituents in a reduction chamber during heating and mixing  190 , and adding  192  pavement renewal materials to the degraded pavement constituents to rejuvenate the pavement as needed. Finally, in some embodiments, a method in accordance with the present invention may include performing  196  finishing processes to finish the recycled paved surface. Finishing processes may include, for example, cleaning  198  the recycled paved surface, and/or marking  200  the recycled paved surface as appropriate.  
         [0069]     The present invention may be embodied in other specific forms without departing from its essence or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes within the meaning and range of equivalency of the claims are to be embraced within their scope.

Technology Classification (CPC): 4