APPARATUS FOR USE IN A PAVING OPERATION

Abstract

A primary furnace device is adapted to heat a paved area to a first predetermined temperature. A secondary furnace device is adapted to heat the paved area to a second predetermined temperature via a multi-stage process having at least two heating zones interspersed with at least one soaking zone. A heater/shaver is adapted to heat the paved area to a third predetermined temperature and to shave the heated paved area to a predetermined depth to create a first mixture located upon a substrate. A mixer/finisher is adapted to collect the first mixture, mix the first mixture, and produce recycled pavement. The primary furnace device, secondary furnace device, heater/shaver, and mixer/finisher travel in series along the paved area in a longitudinal direction. A method of recycling pavement is also provided.

Description

TECHNICAL FIELD

The present invention relates to an apparatus for use in a paving operation.

BACKGROUND OF THE INVENTION

When a roadway, parking lot, or other paved area becomes sufficiently worn from use, weather, or other causes, it is often desirable to resurface or repave the paved area. In conventional resurfacing processes, pavement is mechanically removed from the paved area, by a scarifier or a rotary milling machine. The pavement may be preheated to facilitate such removal. The loose pavement produced by such a process may be recycled. The loose pavement is treated to renew the material properties of the asphalt already present within the loose pavement. The recycled loose pavement may be laid back down on the substrate or transported away for use in another paved area.

SUMMARY OF THE INVENTION

According to an embodiment of the present invention, an apparatus is described. A primary furnace device is adapted to heat a paved area to a first predetermined temperature. A secondary furnace device is adapted to heat the paved area to a second predetermined temperature via a multi-stage process having at least two heating zones interspersed with at least one soaking zone. A heater/shaver is adapted to heat the paved area to a third predetermined temperature and to shave the heated paved area to a predetermined depth to create a first mixture located upon a substrate. A mixer/finisher is adapted to collect the first mixture, mix the first mixture, and produce recycled pavement. The primary furnace device, secondary furnace device, heater/shaver, and mixer/finisher travel in series along the paved area in a longitudinal direction.

According to an embodiment of the present invention, a furnace device for heating pavement during a paving operation is described. A heating system has a plurality of heating zones. The plurality of heating zones are arranged in a longitudinal direction relative to the direction of movement of the furnace device relative to the pavement. Each of the heating zones is separately controllable and spaced apart from each other by at least one soaking zone. A suspension system supports the plurality of heating zones for movement along the paved area.

According to an embodiment of the present invention, a pavement mixer/finisher for processing pavement during a paving operation is described. A suspension system is adapted to support the mixer/finisher for movement along a paved area. A mixing plant includes a drum and an auger. The auger is rotatable relative to the drum. The drum extends substantially parallel to the paved area. The mixing plant is adapted to transform the first mixture into recycled pavement. An intake device is adapted to deliver the first mixture to the mixing plant. An output device is adapted to deliver the recycled pavement from the mixing plant.

According to an embodiment of the present invention, a method of recycling pavement is described. A paved area is heated to a first predetermined temperature. The paved area is heated to a second predetermined temperature via a multi-stage process with a furnace device having first and second heating zones fixedly connected to each other and spaced apart from each other. The paved area is heated to a third predetermined temperature. The heated paved area is shaved to a predetermined depth to create a first mixture located upon a substrate. The first mixture is collected. The first mixture is mixed. Recycled pavement is produced. The steps of heating the paved area to the first predetermined temperature, heating the paved area to the second predetermined temperature, heating the paved area to the third predetermined temperature, shaving the heated paved area, collecting the first mixture, mixing the first mixture, and producing recycled pavement occur in series.

According to an embodiment of the present invention, a system for recycling pavement is described. Means for heating a paved area to a first predetermined temperature is provided. Means for heating the paved area to a second predetermined temperature via a multi-stage process with at least two heating periods interspersed with at least one soaking period is provided. The means for heating the paved area to a second predetermined temperature includes a furnace device having first and second heating zones fixedly connected to each other and spaced apart from each other. Means for heating the paved area to a third predetermined temperature is provided. Means for shaving the heated paved area to a predetermined depth to create a first mixture located upon a substrate is provided. Means for collecting the first mixture is provided. Means for mixing the first mixture is provided. Means for producing recycled pavement is provided. The means for heating the paved area to the first predetermined temperature, means for heating the paved area to the second predetermined temperature, means for heating the paved area to the third predetermined temperature, means for shaving the heated paved area, means for collecting the first mixture, means for mixing the first mixture, and means for producing recycled pavement operate in series along the paved area in a longitudinal direction.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference may be made to the accompanying drawings, in which:

FIG. 1 is a schematic side view of an exemplary embodiment of a multi-stage apparatus according to the present invention;

FIG. 2 is a schematic cross-sectional side view of a first furnace device of the multi-stage apparatus depicted in FIG. 1;

FIG. 3a is a schematic partial side view of the furnace device depicted in FIG. 2;

FIG. 3b is a schematic partial plan view of the furnace device depicted in FIG. 2;

FIG. 4 is a schematic partial plan view of the furnace device depicted in FIG. 2;

FIG. 5 is a schematic process view of the furnace device depicted in FIG. 2;

FIG. 6 is a schematic cross-sectional side view of a second furnace device of the multi-stage apparatus depicted in FIG. 1; and

FIG. 7 is a schematic cross-sectional side view of a heater/shaver of the multi-stage apparatus depicted in FIG. 1; and

FIG. 8 is a schematic partial cross-sectional side view of a mixer/finisher of the multi-stage apparatus depicted in FIG. 1.

DESCRIPTION OF EMBODIMENTS

In accordance with the present invention, FIG. 1 depicts an exemplary embodiment of a multi-stage apparatus 100 for use in paving a road, parking lot, or other paved area (shown generally at 102, actually extending out of and into the plane of FIG. 1). The multi-stage apparatus 100 may be used for repaving or in-place recycling of pavement in a paving application, such as a road or parking lot resurfacing.

The multi-stage apparatus 100 includes at least one primary pavement heater or furnace device 104 and at least one secondary pavement heater or furnace device 106. The primary and secondary furnace devices 104 and 106 are adapted to heat the pavement 108 of a paved area 102 to a predetermined depth and temperature. The predetermined depth and temperature are chosen to soften the pavement 108 in a desired manner for removal from a substrate 110 (a portion of which is shown in cutaway in FIG. 1). The substrate 110 may be other pavement or any other suitable material. The predetermined depth and temperature may be based on an atmospheric temperature, a composition of the pavement 108, a thickness of the pavement 108, a thickness of the substrate 110, a material of the substrate 110, other functions performed by the primary and secondary furnace devices 104 and 106, or any other desired factors or combinations thereof.

The primary furnace device 104 includes a furnace body 212, shown in greater detail in FIG. 2, which is adapted to heat the paved area 102 to a first predetermined temperature. The furnace body 212 includes a fuel source 214, a furnace body frame 216, and a plurality of heating elements or heads 218 (most left unlabeled for clarity). The fuel source 214 may be a gas tank, such as the propane tank 214 shown in FIG. 2, or may be a fuel cell, battery, or any other suitable fuel source 214. The furnace body frame 216 is adapted to support and optionally enclose the fuel source 214. The furnace body frame 216 includes a plurality of furnace body supports 220 which are connected to make up the furnace body frame 216. The furnace body supports 220 may be connected by welding, riveting, bolting, or the like. The furnace body supports 220 may provide a framework for substantially enclosing the fuel source 214 with a suitable furnace covering system (labeled 122 in FIG. 1, omitted from FIG. 2 for clarity), such as an enclosure of sheet metal, fiberglass, or the like.

A suspension system 224 is adapted to support the furnace body 212 for movement in a longitudinal direction along the paved area 104. The suspension system 224 includes a plurality of wheels 226, a suspension frame 228 supported by the wheels 226, and a heating frame (shown generally at 230) carried by the suspension frame 228. The heating frame 230 is adapted to movably hold the heating heads 218 a predetermined distance from the pavement 108. The distance between the heating heads 218 and the pavement 108 of the primary furnace device 204 may be optimized to heat the pavement 108 to the first predetermined depth and temperature.

In the primary furnace device 104 shown in FIG. 2, the heating frame 230 is comprised of first and second heating frames 230a and 230b, which can be controlled, powered, moved, and otherwise utilized separately, if desired. Alternately, the first and second heating frames 230a and 230b of the primary furnace device 104 may be considered to make up a combined heating frame 230. The first and second heating frame 230a and 230b components of this heating frame 230 may be moved and mounted in a unitary manner but may also be controlled separately to achieve a differential heat application to the pavement 108, when desired. Each heating frame 230 will be generally presumed herein to be of a basic one-piece type for simplicity of discussion, though one of ordinary skill in the art can readily provide independently movable and/or operable first and second heating frames 230a and 230b for a particular application of the present invention.

The distance between the heating heads 218 and the pavement 108 may be changed as desired during operation of the primary furnace device 204 by moving the heating frame 230 with a height adjustment mechanism 232. The height adjustment mechanism 232 of the heating frame 230 may be of any suitable type, such as a piston cylinder arrangement, a rack-and-pinion system, a cotter pin and suspension arm arrangement, or the like.

An exemplary arrangement of the plurality of heating heads 218 of the primary furnace device 104 is shown in the grid-type layout of FIGS. 3a and 3b. The plurality of heating heads 218 may define a plurality of separately controllable heating zones 334a, 334b, and 334c, which are arranged in the longitudinal direction relative to the direction of movement of the primary furnace device 104 relative to the pavement 108. The suspension system 224 supports the plurality of heating zones 334 for movement along the paved area 102.

An operator of the primary furnace device 104 may control the heat output by each heating zone 334 based upon the temperature of the pavement 108 beneath that heating zone 334, and thereby use the plurality of adjacent heating zones 334 to heat the pavement 108 to the first predetermined temperature. Although three heating zones 334a, 334b, and 334c are shown, any desired number of heating zones may be provided, and in any desired configuration (e.g., split across multiple hearing frames 230a, 230b, and the like).

An experienced operator may be able to determine whether the pavement 108 has reached the predetermined temperature based upon the appearance of the pavement 108, a sensed temperature at a certain distance from the pavement 108, or another observable factor combined with the operator's experience and training. The operator may then control each heating zone 334 of the primary furnace device 104 individually to bring the pavement 108 to the first predetermined temperature without overheating and scorching the topmost surface of the pavement 108.

The longitudinal arrangement of heating zones 334a, 334b, 334c allows for ongoing temperature observation and adjustment as the pavement 108 is heated. Therefore, the operator has greater control of the temperature of the entire pavement 108 with the use of heating zones 334 than if the pavement 108 were merely subjected to one pass of a fixed-temperature array of heating heads 218.

The primary furnace device 104 includes a heating system 236 adapted to provide air to the heating heads 218. The heating system 236 includes at least one fan 238 and an air box 240. The fan 238 is located within the furnace body 212, which may be enclosed by the furnace covering system 122. The air box 240 is associated with the heating frame 230 and is adapted to absorb heat, directly or indirectly, from the heating frame 230. The heating frame 230 may form a portion of the structure of the air box 240, but will be discussed as a separate structure herein for clarity. Because FIG. 2 depicts an example configuration of the primary furnace device 104 which includes first and second heating frames 230a and 230b, this Figure also shows a plurality of heating systems 236, 236′, with each heating system having a fan 238, 238′ and an air box 240, 240′ and being associated with a heating frame 230a, 230b. Each of the heating systems 236, 236′ will operate similarly and both will thus be discussed as a single heating system 236 (with related components) below. It is contemplated, however, that in an embodiment of the primary furnace device 104 including a single heating frame 230, only a single heating system 236 may be provided.

The fan 238 draws ambient air from inside the furnace body 212 and sends the ambient air to the air box 240. The air circulated through the air box 240 absorbs heat, which has traveled into the air box 240 from the heating frame 230, the heating heads 218, and the pavement 108. Accordingly, the air circulated through the air box 240 cools the heating frame 230 to help prevent damage to the heating frame 230.

The heating system 236 provides the ambient air from within the furnace body 212 to the heating heads 218 through use of the air box 240. As depicted in plan view in FIG. 4, the air box 240 is a ductwork structure adjacent the heating frame 228 and connected to the fan 238 by a transmission duct 242 (shown in FIG. 2). One possible airflow routing is shown by the arrows in FIG. 4. Air is passed to the air box 240 from the transmission duct 242 via the air box's air intake 444. Once in the air box 240, the airflow circulates to the heating heads 218, optionally under pressure from the fan 238. The airflow may roam freely within a relatively open air box 240 structure or may be directed to one or more heating heads 218 through at least one circulation duct 446 (several left unlabeled for clarity), such as the sample grid arrangement of a plurality of circulation ducts shown in FIG. 4.

Regardless of the way in which the airflow is routed, the air box 240 is in fluid communication with an air intake (not shown) of each heating head 218 to supply heated air, which may be under pressure, for the combustion process. The fuel source 214 supplies fuel for combustion through a fuel line (not shown in this view), which runs between the fuel source 214 and at least one heating head 218.

Any suitable heating head 218 may be used in the multi-stage apparatus 100 of the present invention. For example, a heating head 218 which may be suitable for certain applications of the present invention is disclosed in co-pending U.S. patent application Ser. No. ______, “Burner for Paving Apparatus”, attorney docket no. ARS-018374 PRI, filed concurrently with the instant application and incorporated wholly by reference herein.

In the exemplary embodiment of the Figures, the fuel supplied is propane and the heating head 218 includes an ignition source (not shown) to spark the combustion process. The heat resulting from the combustion of the fuel and the heated air is supplied to the pavement 108 by the heating head 218. By supplying heated air to the heating heads 218 through the air box 240, the primary and secondary furnace devices 104 and 106 require less fuel to achieve a desired heat output from the combustion process than if ambient air were used for combustion.

As shown in FIG. 5, a fuel valve 548 is associated with each heating zone 344. Each fuel valve 548 may be individually controlled to adjust an amount of heat supplied by the heating heads 218 of that heating zone 334 to the pavement 108 by controlling the flow of fuel from the fuel source 218 to one or more heating heads 218 through a fuel line 550. In the simplest control method, each fuel valve 548 is either on or off and may be selectively changed between the two by an operator or a control system (not shown). Any suitable control method for the fuel valve(s) 548, either manual or automatic, may be used.

The heating zones 334a, 334b, and 334c may each be associated with at least one zone sensor (not shown). The zone sensor may be adapted to control the fuel valve 548, and thereby the associated heating zone 334, to heat the pavement 108 to the predetermined temperature instead of or in addition to an operator who manually judges the heat of the pavement 108 beneath each heating zone 334.

Although the exemplary embodiment uses heated air in combustion, the heating system 236 may also or instead supply heated air from the heating frame 230 directly to the pavement 108.

The furnace body 212 and associated structures can be made of relatively lighter materials when the heating system 236 is present than which would otherwise be needed to resist warping and other heat damage to the heating frame 230 or other structures of a primary or secondary furnace device 104 or 106 with no circulation of air. Therefore, use of the heating system 236 may result in cost savings in construction and operation of the primary and secondary furnace devices 104 and 106. The heating system 236 may even allow for use of the lighter multi-stage apparatus 100 on roads with a relatively thin roadbed substrate 110 while avoiding load-related damage to the paved area 102 that heavier resurfacing equipment might cause.

FIG. 6 depicts a secondary furnace device 106 which may be used with the multi-stage apparatus 100. The secondary furnace device 106 is similar to the primary furnace device 104 and corresponding structures in both will be indicated by the same element numbers.

The secondary furnace device 106 is adapted to heat the paved area 102 to a second predetermined temperature via a multi-stage process having at least two heating zones 334 interspersed with at least one soaking zone 652. As shown in FIG. 6, each heating frame 230 of the secondary furnace device 106 is considered to be one heating zone 334 for simplicity of description, though one of ordinary skill in the art could readily provide a plurality of heating zones 334 on each heating frame 230 in a similar manner to the arrangement shown in FIGS. 3a and 3b, which may include providing at least first and second heating frames 230a and 230b. Similarly, the soaking zone 652 which spaces apart the heating zones 334 in the secondary furnace device 106 of FIG. 6 is provided by the positioning of the heating frames 230 in a spaced-apart configuration on the suspension frame 228 of the secondary furnace device. However, one of ordinary skill in the art could readily provide at least one soaking zone 652 interspersed between two or more heating zones 334 on a single heating frame 230.

The secondary furnace device 106 includes two spaced-apart heating frames 230a, 230b, in contrast to the primary furnace device 106, in which multiple heating frames 230a, 230b, when provided, are located directly adjacent each other. In the embodiment shown in FIG. 6, each heating frame 230a, 230b is associated with a separate fan 238. 238′ and transmission duct 242, 242′ of the heating systems 236, 236′. Each fan 238, 238′ circulates combustion air through the secondary furnace device 106 to cool the corresponding heating frame 230a, 230b, although it is contemplated that any number of fans 238, 238′ could each be associated with any number of heating frames 230a, 230b for a selected furnace device 104 or 106.

The rear heating frame 230b (toward the right side of the view of FIG. 6) of the secondary furnace device 106 is fixed to the suspension frame 228, but may be selectively pivoted toward and away from the paved area 102, as shown by arrow 654 and the phantom-line alternate position depiction of the heating frame in a raised position. The height adjustment mechanism 232 of a pivotable heating frame may also be adapted for linear/sliding vertical movement of the heating frame, and may be manually and/or automatically powered and controlled to adjust a height of the heating frame over the paved area 102 as desired to bring the pavement 108 to the appropriate predetermined temperature. Any heating frame 230 of the multi-stage apparatus 100 could be configured for pivotal movement in the manner shown in FIG. 6 for the rear heating frame 230b of the secondary furnace device 106.

Multiple primary and/or secondary furnace devices 104 and 106 and other structures which heat the pavement 108 may be used in a single multi-stage apparatus 100 as desired in a particular paving or resurfacing operation. For example, and as shown in FIG. 1, a desired multi-stage apparatus 100 can include one primary furnace device 104, one secondary furnace device 106, and a heater/shaver 156, which will be discussed below. The primary and secondary furnace devices 104 and 106, and any other heat-producing devices, may be adapted to provide functions in addition to heating the pavement 108 to the predetermined depth and temperature.

As shown in FIG. 7, the heater/shaver 156 includes a heating system 236 and a plurality of heating heads 218, the heating heads being similar in operation to those of the primary and secondary furnace devices 104 and 106. An aggregate source 758 may be carried by the heater/shaver 156 or another component of the multi-stage apparatus 100. When present, the aggregate source 758 may be adapted to selectively release aggregate (not shown), which may be loose rock or gravel, to the paved area 102 at a desired time during the operation of the multi-stage apparatus 100. For example, and as shown in FIGS. 1 and 7, the aggregate source 758 may be positioned on the front of the heater/shaver 156 to release aggregate to the pavement 108 before the rest of the heater/shaver structure travels over the pavement 108. The heater/shaver 156 is adapted to heat the paved area 102 (and associated aggregate, when provided) to a third predetermined temperature and depth. The heater/shaver 156 includes at least one shaving blade 760 adapted to shave the paved area 102 to a predetermined depth and thereby create a first mixture 762 of loose pavement 108 and optional aggregate deposits located upon the substrate 110. By “shave”, what is meant is that a portion of the pavement 108 is pried or cut away from the substrate 110 in a plowing or wedging manner by a substantially longitudinal motion of the blade 760. The shaving blade(s) 760 may have a relatively sharp edge to sever the pavement 108 from the substrate 110 or may be relatively blunt and remove the pavement 108 from the substrate 110 in much the same manner as a snowplow removing snow from a road surface. It is contemplated that the shaving blade 760 may be supported by a manually or automatically powered and/or controlled variable-height suspension system 764. For example, the variable-height suspension system 764 could operate via a spring action, and retract the shaving blade 760 from the paved area 102 responsive to a predetermined resistance force to the shaving action. In this way, the shaving might only extend down through a heat-softened depth of the pavement 108 and thus avoid shaving of portions of the pavement 108 and/or substrate 110 if either has been inadequately softened. Regardless of the mechanism of action, however, the shaving blade 760 is adapted to shave the pavement 108 from the paved area 102 to a selectively variable shaving depth with assistance from the variable-height suspension system, when present.

The shaving of the paved area 102 by the shaving blade(s) 760 may be accomplished in multiple stages, either by multiple passes of the heater/shaver 156 or by multiple shaving blades 760 on the same heater/shaver 156. The multiple shaving blades 760, when present, may be transversely offset across the longitudinal direction of the paved area 102 to provide a total shaving width greater than the width of an individual shaving blade 760. The structure, configuration, or position of each shaving blade 760 may differ within a single configuration of the multi-stage apparatus 100. For example, at least one relatively low-resolution dislodging-type shaving blade could make a rough pass to remove the bulk of the pavement 108, followed by at least one higher-resolution smoothing-type shaving blade to smooth and even out the shaved portions of the paved area 102. Alternately or additionally, a plurality of shaving blades could each be set at a different height to gradually shave down to the predetermined depth. One of ordinary skill in the art could readily provide one or more shaving blades, dislodging blades, and/or smoothing blades and associated components designed to provide shaving functions having these or any other desired effects, finishes, and characteristics.

In some applications, the shaving of the pavement 108 may be accomplished by a device which does not include a heat source such as the depicted heating frame 230 and associated heating system 236 of the heater/shaver 156 of FIG. 1. Regardless of whether the heater/shaver 156 includes a heating function, however, use of the shaving blade 760 to remove the pavement 108 results in a relatively smooth substrate 110 to which new pavement 108 may readily adhere.

The heater/shaver 156 may be adapted to place the first mixture 762 on the paved area 102 in a predetermined arrangement, for ease of later collection and/or use, and this placement may be accomplished through the use of at least one material handling tool. For example, the shaving blades 760 or another material handling tool may be adapted to create at least one windrow 766 of the first mixture 762, which may be substantially arranged in a longitudinal direction along the substrate 110 of the paved area 102. Optionally, one or more of the shaving blades 760 may be selectively used to arrange the first mixture 762 into windrows 766 without concurrently performing a shaving function. Another example of a suitable material handling tool for arranging the first mixture 762 as desired is a blunt shovel or plow (not shown) which can urge the first mixture 762 into the desired arrangement but is not suited to performing a shaving operation.

During use of the multi-stage apparatus 100, at least one additive source 768 may supply at least one additive to the first mixture 762 after shaving and/or to the pavement 108 before shaving, or to any incarnation of the pavement 108 and/or paved area 102 at any suitable stage of the pavement recycling process. Additional additive sources (not shown) may be provided to the heater/shaver 156 or another component of the multi-stage apparatus 100. For example, at least one other additive source could be carried by the heater/shaver 156 at a location spaced apart from the additive source 768. The additive(s) may be applied directly to the pavement 108, to the windrow(s) 766 on the substrate 110, or to the first mixture 762 within a separate transport or mixing device. The additive may be, for example, a rejuvenating agent which acts in a known manner to refresh and renew the material properties of the asphalt (not shown) contained within the pavement. The additive, when present, may be applied in combination with a heating operation, depending upon the desired paving application. In some applications of the present invention, and as described above, the additive may be an aggregate, supplied to the first mixture 762 by the aggregate source 758. As used herein, the term “additive” refers to a liquid, solid, powder, gel, or any other suitable composition or substance, including aggregate rock, which is added to the paved area 102, pavement 108, and/or substrate 110 from any source and at any time before, during, or after operation of the multi-stage apparatus 100, in order to provide desired properties to recycled pavement produced by the multi-stage apparatus. The same additive, or type of additive, may be provided multiple times during a single processing cycle, as well.

For example, a first additive may be provided to soften the pavement 108 (optionally before the pavement is shaved), a second additive may be provided to strengthen the pavement (optionally after the pavement has been shaved), a third additive may be provided to strengthen the bond between individual components which make up the pavement (optionally after the pavement has been shaved), and a fourth additive—which may be aggregate—may be provided at any suitable time in the process to achieve desired physical properties in the final recycled pavement material. Regardless of the timing and/or nature of the additive(s) being added to the first mixture 762, an auger 770 carried by the heater/shaver 156 may mix at least one additive and the first mixture 762 to form an additive mixture 772. The additive mixture 772, which may include additives from the aggregate source 758, additive source 768, and/or any other suitable source, may be formed into the windrows 766 upon the substrate 110 as the auger 770 ejects the additive mixture.

The windrows 766 may be formed by natural action of the auger 770 or may be formed by one or more shaving blades 760 or by baffles (not shown) that direct the first mixture 762 or the additive mixture 772 to pile into windrows 766. It is contemplated that the pavement 108 may be gradually shaved to the desired depth by a series of passes of successive shaving blades 760 carried by one or more heater/shavers 156, and that the additive, when present, could be added at any suitable time during such a staged shaving operation. For simplicity, the following description will refer to the “first mixture” as being the output of the heater/shaver 156. However, one of ordinary skill in the art will recognize that, where a “first mixture” is referenced, an additive mixture 772 may be substituted in the referenced operation for applications of the present invention in which one or more additives are used.

A pavement mixer/finisher 174, as depicted in the exemplary embodiment of FIGS. 1 and 8, is supported for movement along the paved area 102 by a suspension system 876. The mixer/finisher 174 includes a scoop 878 or other intake device adapted to collect the first mixture 762, either from windrows 766 formed by the shaving blades 760 or auger 770 or from a more random scattering across the substrate 110 of the paved area 102. The mixer/finisher 174 then mixes the first mixture 762 in a mixing plant 880 to produce recycled pavement 882, as shown in FIG. 8.

The mixing plant 880 includes a drum 884 extending substantially parallel to the paved area 102 and an auger 886 located within the drum 884. As can be seen in FIG. 8, the drum 884 may be slightly tilted upward from the paved area 102, but a slight slope angle (such as that shown) of 15° or less is considered to be “substantially parallel”, as used herein. The auger 886 is rotatable relative to the drum 884. The auger 886 may include paddles, posts, or other protrusions (such as the paddle shown schematically at 888) to assist in breaking up and mixing the first mixture 762 into recycled pavement 882 as the first mixture 762 travels through the drum 884. As shown in FIG. 8, the auger 886 may include a rotatable helical flange 890. When present, the helical flange 890 may have a pitch in the range of 20-30° from the vertical. Any desired number and configuration(s) of paddle(s) 888 or other protrusions may extend from any surface of the mixing plant 880 and may have any desired orientations; for example, the paddles may be located at 25° intervals around the circumference of the helical flange 890.

The mixer/finisher 174 may heat the first mixture 762 before, during, and/or after mixing, through the use of ambient or externally-provided heat, heat provided by other components of the multi-stage apparatus, and/or heat generated by or within the mixer/finisher itself, which could be accomplished with a heating system 236 much like those of the primary and secondary furnace devices 104 and 106. Also, the mixer/finisher 174 may include at least one additive source 768 which is adapted to supply at least one additive, such as a rejuvenating agent or an aggregate, to the first mixture 762 within the mixing plant 880, before, during, and/or after mixing and either in addition to, or instead of, an earlier-added additive. For example, one or more additive sources 768, adapted to supply any or all of the aforementioned first, second, and third additives to the first mixture 762, may be associated with the mixing plant 880. Regardless of the additive(s) supplied or mechanical operations which occur, the mixing plant is adapted to transform the first mixture 762 into recycled pavement 882.

Just as the scoop 878 or another intake device (not shown) may be adapted to deliver the first mixture 762 to the mixing plant 880, a baffle 892 or other output device (not shown) may be adapted to help deliver the recycled pavement 882 from the mixing plant. The baffle 892 (seen from the side in the view of FIG. 8) may help in controllably routing the recycled pavement 882 into a scattering or freefall onto the paved area 102 behind the mixer/finisher 174. When present, the baffle 892 may be a simple shaped plate, or may include additional manually or automatically actuated and/or powered moving components.

Additionally or alternatively to the baffle 892, one or more plow blades 894 may be provided on the mixer/finisher 174 to assist with placement of the recycled pavement 882 into a desired arrangement on the paved area 102, such as into windrows (not shown) similar to those produced by the heater/shaver 156. Once the recycled pavement 882 is on the paved area 102, the recycled pavement may be collected for later use or re-installed onto the original paved area. It is also contemplated that the recycled pavement 882 may be ejected directly from the mixing plant 880 into a hopper (not shown) carried by the mixer/finisher 174, or into a trailer (not shown) or other separate transportation device for use in another location and/or at a later time.

Multiple primary and/or secondary furnace devices 104 and 106, no matter what additional functions may be provided by each, may travel in series with at least one heater/shaver 156 and mixer/finisher 174 in a longitudinal direction along the paved area 102 to comprise the multi-stage apparatus 100 depicted in FIG. 1 (the longitudinal direction being from right to left along the plane of the page of FIG. 1). Such sequential travel may include a physical connection between successive primary and secondary furnace devices 104 and 106, the heater/shaver 156, and the mixer/finisher 174, as shown by the connections A-A, B-B, and C-C of FIG. 1. Any of the primary and secondary furnace devices 104 and 106, the heater/shaver 156, and the mixer/finisher 174 may be controlled to the extent desired by a central controller (not shown) of the multi-stage apparatus 100. Alternatively, primary and secondary furnace devices 104 and 106, the heater/shaver 156, and the mixer/finisher 174 may be used separately and/or in any combination or order with each other as desired for a particular paving operation.

In use, an operator evaluates a paved area 102 to determine the properties of the existing pavement 108 and responsively produces a formal or informal plan for removing and/or recycling the material of the paved area. This plan might include the provision of calculated values for the first, second, third, and fourth predetermined temperatures, as well as the specification of specific types and amounts of additives for use in the process. Additionally, a direction and/or speed of travel of the multi-stage apparatus 100 across the paved area 102 may be specified. It is contemplated, however, that the plan may be readily changed as desired during operation of the multi-stage apparatus 100.

Once the preliminary planning steps have been completed, the multi-stage apparatus 100 travels in a longitudinal direction along the paved area 102 which is to be resurfaced. The primary furnace device 104 passes over the paved area 102, supplies heat to the pavement 108 from the heating heads 218, and controls the temperature of the pavement 108 associated with each heating zone 334. The operator of the primary furnace device 104 manually or automatically controls the height and actuation of the heating heads 218 in each heating zone 334, separately or together, to bring the pavement 108 to the first predetermined temperature.

Once the primary furnace device 104 has passed over a section of the pavement 108, that section rests or soaks for a period of time to allow the applied heat to penetrate from the very top surface of the pavement 108 into the depth of the pavement 108 toward the substrate 110. This soaking period may prevent scorching or burning of the top of the pavement 108 while still achieving a suitable temperature rise through the depth of the pavement 108 to provide desired resurfacing properties.

Next, a secondary furnace device 106 passes over the same section of the paved area 102 that was previously heated by the primary furnace device 104. The secondary furnace device 106 applies heat to the pavement 108 in a similar manner to that of the primary furnace device 104, to bring the pavement 108 to a second predetermined temperature. However, and as previously discussed, the secondary furnace device 106 includes first and second (and optionally additional) heating zones 334 fixedly connected to each other and spaced apart from each other. Accordingly, the secondary furnace device 106 heats the paved area 102 to a second predetermined temperature via a multi-stage process with at least two heating periods (each heating period associated with the passage of a heating zone 334 over the paved area) interspersed with at least one soaking period (each soaking period associated with the lack of a heating zone 334 over the paved area). The pavement 108 may then be once again permitted to soak in the applied heat.

Once the primary and secondary furnace devices 104 and 106 have passed over the paved area 102 in the exemplary embodiment of the multi-stage apparatus 100 shown in FIG. 1, the heater/shaver 156 may pass over the paved area. The heating frame 230 of the heater/shaver 156 may heat the paved area 102 to a third predetermined temperature, either in a single step or via a multi-stage process like that of the secondary furnace device 106. Optionally, a soaking zone 652 may be provided once the heating frame 230 of the heater/shaver 156 has passed the paved area 102.

As shown in FIG. 1, once the paved area 102 reaches the third predetermined temperature, at least one shaving blade 760 shaves away the pavement 108 from the substrate 110 of the paved area 102 to a desired depth. The depth of shaving may be predetermined or may be determined during the shaving process responsive to a factor such as a penetration depth of heat applied by other component(s) of the multi-stage apparatus 100. The shaving blade(s) 760 optionally pile the resulting first mixture 762 (comprised mainly of loose pavement 110, along with some amount of dirt and debris; an additive such as aggregate may be provided to the first mixture) into at least one windrow 766 upon the substrate 110. One or more additives may be added to the windrow(s) 766 of the first mixture 762 by an additive source 768, such as a liquid sprayer or pellet hopper, located at an appropriate position on the heater/shaver 156. The additive, when present, could instead or also be added to the pavement 108 before or after shaving or before or after the paved area 102 is heated.

In the exemplary embodiment of FIG. 1, an auger 770 may optionally gather the windrows 766 of the first mixture 762 lying atop the substrate 110 of the paved area 102, optionally after aggregate or one or more other additives have been added to the windrows 766. When an additive is provided directly to the first mixture 762 (which may occur before or after the first mixture has been placed in windrows 766), the auger 770 mixes the additive and the first mixture 762 to produce an additive mixture 772, which is then ejected from the auger 770 onto the substrate 110. The auger 770 may be configured, positioned, and/or controlled to shape the resulting windrows or loose piles of additive mixture 772 as desired. It is to be understood that the term “first mixture” 762, as used herein, may comprise any desired additive mixture.

In another optional operation of the multi-stage apparatus 100 of FIG. 1, an aggregate (not shown) may be supplied to the first mixture 762, for example, by an aggregate source 758 or another additive source 768 of the heater/shaver 156, at any time before, during, or after shaving of the pavement 108 to form the first mixture 762. The aggregate, when present, could be mixed into the first mixture 762 to form an aggregate mixture (not shown) in a similar manner to the formation of the additive mixture previously discussed. Such an aggregate mixture will also be understood to comprise an additive mixture 772, for purposes of the instant discussion.

The aggregate could passively absorb heat from the first mixture 762 during a soaking period after the aggregate has been added to the first mixture. Alternately, the combination of the aggregate and the first mixture 762 may be actively heated to a fourth predetermined temperature, again optionally using a zone system including a heating frame (not shown) incorporating heating heads (not shown) to achieve the fourth predetermined temperature. The aggregate and first mixture 762 could then be allowed to soak at the fourth predetermined temperature.

A mixer/finisher 174 travels behind the heater/shaver 156 of the FIG. 1 exemplary embodiment and collects the windrows 766 of the first mixture 762 (or of any optional aggregate mixture or additive mixture, as appropriate), optionally with a scoop 878. The mixer/finisher 174 may heat the first mixture 762; add any desired additive, such as aggregate and/or one or more of the first, second, and third additives; mix the first mixture more thoroughly; add heat to, and/or remove heat from, the first mixture 762; and/or otherwise manipulate the first mixture to produce recycled pavement 882 having desired properties. The scoop 878 supplies the first mixture 762 to the mixing plant 880, which uses the rotational motion between the auger 886 and the drum 884 to mix the first mixture into recycled pavement 882. For example, whether or not an additive of any type was previously provided to the first mixture 762, the mixer/finisher 174 may mix the first mixture within the drum 884 for a time period of at least ninety seconds. The newly-formed recycled pavement 882 may be left on the substrate 110 of the paved area 102 or may be transferred from the mixing plant 880 to a paver hopper (not shown) or another paving material collection/transport device, such as a dump truck (not shown). The recycled pavement 882 may then be used with any suitable paving method for resurfacing of the paved area 102 or may be transported to another area to surface or resurface a different paved area.

In the embodiment shown in FIG. 1, the steps of heating the paved area 102 to the first predetermined temperature, heating the paved area 102 to the second predetermined temperature, heating the paved area 102 to the third predetermined temperature, shaving the heated paved area 102, collecting the first mixture 762, mixing the first mixture 762, and producing recycled pavement 882 occur in series. Optionally, these steps, in addition to occurring serially, also occur in the listed sequence.

While aspects of the present invention have been particularly shown and described with reference to the preferred embodiment above, it will be understood by those of ordinary skill in the art that various additional embodiments may be contemplated without departing from the spirit and scope of the present invention. For example, the heating system 236 may supply heated air to the heating heads 218 or pavement 108 in a different manner than described; one or more heating frames 230 of each furnace device 104 and 106 may be vertically movable with respect to the paved area 102 in a linear and/or pivoting manner; the transmission duct 242 and other components of the heating system 236 may be flexible, segmented, or otherwise adapted to facilitate height adjustment of an associated heating frame 230; the multi-stage apparatus 100 could include at least one secondary furnace device 106 and no primary furnace device 104; two or more of the first, second, third, and fourth predetermined temperatures may be substantially the same temperature; a user of the secondary furnace device 106 could provide at least one soaking zone 652 or soaking period by simply declining to activate at least one heating zone 334 to simulate a spacing-apart of the adjacent heating zones; each primary and secondary furnace device 104 and 106, heater/shaver 156, and mixer/finisher 174 may be pushed, towed, or self-propelled; the primary and secondary furnace device 104 and 106, heater/shaver 156, and mixer/finisher 174 may each be controlled remotely or on-board; several of the heating, additive-adding, shaving, and mixing functions may be combined in a single furnace device 104 or 106; or various mixtures of pavement 108 and an additive such as rejuvenating agent and/or aggregate may be combined and mixed at different times than those described above. However, a device or method incorporating such an embodiment should be understood to fall under the scope of the present invention as determined based upon the claims below and any equivalents thereof.

Other aspects, objects, and advantages of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims.

Claims

1. An apparatus comprising:

a primary furnace device adapted to heat a paved area to a first predetermined temperature;

a secondary furnace device adapted to heat the paved area to a second predetermined temperature via a multi-stage process having at least two heating zones interspersed with at least one soaking zone;

a heater/shaver adapted to heat the paved area to a third predetermined temperature and to shave the heated paved area to a predetermined depth to create a first mixture located upon a substrate; and

a mixer/finisher adapted to collect the first mixture, mix the first mixture, and produce recycled pavement;

the primary furnace device, secondary furnace device, heater/shaver, and mixer/finisher traveling in series along the paved area in a longitudinal direction.

2. The apparatus of claim 1, wherein the heater/shaver includes a shaving blade supported by a variable-height suspension system, the shaving blade being adapted to shave the pavement from the paved area to a variable shaving depth responsive to the variable-height suspension system.

3. The apparatus of claim 1, further comprising at least one aggregate source adapted to supply aggregate to the first mixture.

4. The apparatus of claim 1, further comprising at least three additive sources adapted to supply at least three additives to the first mixture.

5. The apparatus of claim 1, wherein the mixer/finisher includes:

a suspension system adapted to support the mixer/finisher for movement along a paved area; a mixing plant including a drum and an auger, the auger being rotatable relative to the drum, the drum extending substantially parallel to the paved area, and the mixing plant being adapted to transform the first mixture into recycled pavement; an intake device adapted to deliver the first mixture to the mixing plant; and an output device adapted to deliver the recycled pavement from the mixing plant.

6. The apparatus of claim 5, wherein the auger includes a rotatable helical flange, and the pitch of the flange is in the range of 20-30 degrees from the vertical.

7. The apparatus of claim 5, wherein the mixing plant includes at least two additive sources, adapted to supply at least two additives to the first mixture within the mixing plant.

8. The apparatus of claim 5, wherein the mixing plant is configured to mix the first mixture for a time period of at least ninety seconds.

9. The apparatus of claim 5, wherein the mixing plant is configured to add heat to the first mixture during the mixing process.

10. The apparatus of claim 1, wherein the primary furnace device heats the paved area to the first predetermined temperature using a plurality of adjacent heating zones.

11. The apparatus of claim 10, wherein at least one heating zone includes an air box adapted to direct airflow to at least one heating head through at least one circulation duct.

12. The apparatus of claim 1, wherein the heater/shaver is adapted to place the first mixture on the paved area in a predetermined arrangement.

13. The apparatus of claim 12, wherein the heater/shaver includes at least one material handling tool adapted to place the first mixture in the predetermined arrangement.

14. A furnace device for heating pavement during a paving operation, the furnace device comprising:

a heating system with a plurality of heating zones, the plurality of heating zones being arranged in a longitudinal direction relative to the direction of movement of the furnace device relative to the pavement, each of the heating zones being separately controllable and spaced apart from each other by at least one soaking zone; and

a suspension system that supports the plurality of heating zones for movement along the paved area.

15. The furnace device of claim 14, further comprising:

a heating frame and a heating system for heating the pavement, the heating frame being adapted to support at least one heating zone, and the heating system being adapted to circulate combustion air through the furnace device to cool the heating frame.

16. The furnace device of claim 15, wherein an air box directs combustion air to at least one heating head through at least one circulation duct.

17. A pavement mixer/finisher for processing pavement during a paving operation, the mixer/finisher comprising:

a suspension system adapted to support the mixer/finisher for movement along a paved area;

a mixing plant including a drum and an auger, the auger being rotatable relative to the drum, the drum extending substantially parallel to the paved area, and the mixing plant being adapted to transform the first mixture into recycled pavement;

an intake device adapted to deliver the first mixture to the mixing plant; and

an output device adapted to deliver the recycled pavement from the mixing plant.

18. The pavement mixer/finisher of claim 17, wherein the auger includes a rotatable helical flange, and the pitch of the flange is in the range of 20-30 degrees from the vertical.

19. The pavement mixer/finisher of claim 17, wherein the mixing plant includes at least two additive sources, adapted to supply at least two additives to the first mixture within the mixing plant.

20. The pavement mixer/finisher of claim 17, wherein the mixing plant is configured to mix the first mixture for a time period of at least ninety seconds.

21. The pavement mixer/finisher of claim 17, wherein the first mixture is heated within the mixing plant.

22. A method of recycling pavement, the method comprising the steps of:

heating a paved area to a first predetermined temperature;

heating the paved area to a second predetermined temperature via a multi-stage process with a furnace device having first and second heating zones fixedly connected to each other and spaced apart from each other;

heating the paved area to a third predetermined temperature;

shaving the heated paved area to a predetermined depth to create a first mixture located upon a substrate;

collecting the first mixture;

mixing the first mixture; and

producing recycled pavement; wherein

the steps of heating the paved area to the first predetermined temperature, heating the paved area to the second predetermined temperature, heating the paved area to the third predetermined temperature, shaving the heated paved area, collecting the first mixture, mixing the first mixture, and producing recycled pavement occur in series.

23. The method of claim 22, wherein the steps of heating the paved area to the first predetermined temperature, heating the paved area to the second predetermined temperature, heating the paved area to the third predetermined temperature, shaving the heated paved area, collecting the first mixture, mixing the first mixture, and producing recycled pavement occur in the listed sequence.

24. The method of claim 22, wherein at least one of the steps of mixing the first mixture and producing recycled pavement include the steps of

supplying aggregate to the first mixture; and

supplying at least three additives to the first mixture.

25. The method of claim 22, including the step of providing a mixing plant including a drum and an auger, the auger being rotatable relative to the drum, the drum extending substantially parallel to the paved area, and wherein the steps of mixing the first mixture and producing recycled pavement are both performed by the mixing plant.

26. The method of claim 22, wherein the step of mixing the first mixture occurs for a duration of at least ninety seconds.

27. The method of claim 22, wherein the step of mixing the first mixture includes the step of providing heat to the first mixture.

28. The method of claim 22, including the steps of:

evaluating a paved area to determine the properties of the existing pavement; and

responsively producing a plan for recycling the material of the paved area.

29. A system for recycling pavement, the system comprising:

means for heating a paved area to a first predetermined temperature;

means for heating the paved area to a second predetermined temperature via a multi-stage process with at least two heating periods interspersed with at least one soaking period, the means for heating the paved area to a second predetermined temperature including a furnace device having first and second heating zones fixedly connected to each other and spaced apart from each other;

means for heating the paved area to a third predetermined temperature;

means for shaving the heated paved area to a predetermined depth to create a first mixture located upon a substrate;

means for collecting the first mixture;

means for mixing the first mixture; and

means for producing recycled pavement; wherein

the means for heating the paved area to the first predetermined temperature, means for heating the paved area to the second predetermined temperature, means for heating the paved area to the third predetermined temperature, means for shaving the heated paved area, means for collecting the first mixture, means for mixing the first mixture, and means for producing recycled pavement operate in series along the paved area in a longitudinal direction.

30. The system of claim 29, wherein the means for heating the paved area to the first predetermined temperature, means for heating the paved area to the second predetermined temperature, means for heating the paved area to the third predetermined temperature, means for shaving the heated paved area, means for collecting the first mixture, means for mixing the first mixture, and means for producing recycled pavement operate in the listed sequence.

31. The system of claim 29, including means for adding at least three additives to the first mixture.

32. The system of claim 29, including means for heating the first mixture during mixing.