US20130136535A1

US20130136535A1 - Paving system utilizing capsules enclosing a dye

Info

Publication number: US20130136535A1
Application number: US13/308,497
Authority: US
Inventors: James A. Aardema; Aaron Kenneth Amstutz
Original assignee: Caterpillar Paving Products Inc
Current assignee: Caterpillar Paving Products Inc
Priority date: 2011-11-30
Filing date: 2011-11-30
Publication date: 2013-05-30
Also published as: DE112012004965T5; WO2013082099A1; CN103958774A; CN103958774B

Abstract

A method of controlling a paving process is disclosed. The method may include mixing at least one capsule that at least partially encloses a dye within a paving material and dispensing the paving material at a desired location. The method may also include performing a compacting process on the paving material and monitoring for a presence of the dye at a surface of dispensed paving material. The method may further include controlling the compacting process based on the presence of the dye.

Description

TECHNICAL FIELD

The present disclosure relates generally to a paving system, and more particularly, to a paving system utilizing capsules enclosing a dye.

BACKGROUND

Preparation of roadways, building sites, embankments, and other surfaces often requires compaction to produce desired material properties. Compactors are employed to compact various paving materials such as, for example gravel and asphalt material. The desired degree of material compaction can vary based on the type of material being compacted and/or conditions of the material such asphalt temperature. Compaction levels are important for maintaining stability of the paving material. When undercompacted, paving surfaces lack sufficient strength to support traffic loads and are not durable. Overcompacted asphalt can result in permanent deformation of the paving material. During a compaction process, the degree of material compaction can be measured and evaluated for conformity with job specifications.
Traditional methods for determining material compaction have included density measurements and physical testing. Density measurements are conducted using a specialized instrument, such as a nuclear density meter. Soil physical testing is performed by various methods such as by nuclear gauge (NG), light weight deflectometer (LWD), falling weight deflectometer (FWD), and by dynamic cone penetrometer (DCP). Although suitable for some applications, these methods can be cumbersome to apply to an entire project area. In addition, these methods also may result in physical destruction of the project surface when, for example, core samples are taken. Further, these methods may be time consuming as they are usually conducted separate from the compaction process.
An alternative system for monitoring compaction of a surface is described in U.S. Pat. No. 6,122,601 (“the '601 patent”) of Swanson et al. that issued on Sep. 19, 2000. The '601 patent describes a compactor having a compaction meter that takes into account the vibratory response of the compactor when determining compaction of a surface traversed by the compactor. The compactor has intrinsic vibrations from the vibratory mechanism of the compactor's drum(s) that vibrate the compactor as it moves. The compaction meter assumes that, as the compacted material becomes more dense, the vibratory response of the compactor changes. The compaction meter of the '601 patent measures the vibratory response of the compactor and then correlates that response to the compaction level of the asphalt being compacted. The correlation is based on a mathematical model that must account for such parameters as the mass of the compactor, the acceleration of the compactor vibrations, pavement type, mix type, and base type, among others.
The system of the '601 patent may be complex. For example, it may require computerized mapping technology and/or specialized detection equipment and therefore may not be amenable to older paving systems.
The disclosed system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure is directed to a method of controlling a paving process. The method may include mixing at least one capsule that at least partially encloses a dye within a paving material and dispensing the paving material at a desired location. The method may also include performing a compacting process on the paving material and monitoring for a presence of the dye at a surface of dispensed paving material. The method may further include controlling the compacting process based on the presence of the dye.
In another aspect, the present disclosure is directed to a paving mixture. The paving mixture may include a paving material and at least one capsule at least partially enclosing a dye.
In yet another aspect, the present disclosure is directed to a paving system. The paving system may include at least one capsule at least partially enclosing a dye and a paving machine configured to dispense a mixture of paving material and the at least one capsule on a surface. The paving system may also include a compactor configured to compact the mixture dispensed by the paving machine

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side view illustration of a paving system according to one embodiment;

FIG. 2 is a pictorial illustration of an exemplary disclosed dye-filled capsule that may be used with the paving system of FIG. 1;

FIG. 3 is a pictorial illustration of another exemplary disclosed dye-filled capsule that may be used with the paving system of FIG. 1; and

FIG. 4 is a flowchart depicting an exemplary disclosed method performed by the paving system of FIG. 1

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a paving system 10 according to one exemplary embodiment. Paving system 10 may include a plurality of different machines, and in the illustrated embodiment includes a paving machine 12 and a compactor 16. The various machines of paving system 10 are shown approximately as they might appear during paving of a paving material M on a subgrade S. Paving machine 12 may travel across subgrade S and dispense paving material M, which may be subsequently compacted by compactor 16. As further described herein, paving system 10 may be configured to control compactor 16 and, optionally, additional compactors to optimize paving smoothness, depth, and/or a compaction level of paving material M.
Paving machine 12 may generally include a frame 50 configured to support a hopper 52 for temporarily storing paving material M. In the disclosed embodiment, paving material M may be an asphalt material including an aggregate and a binder. It should be noted, however, that other materials may alternatively be utilized, such as gravel and other known paving materials. Paving machine 12 may further include a feeder conveyor 54 and auger(s) 55 configured to dispense paving material M from hopper 52 onto subgrade S for conventional leveling, preliminary compacting, thickness control, etc., via a screed 56. Paving machine 12 may further include a plurality of ground-engaging elements 51, such as wheels or tracks configured to propel paving machine 12, and an operator station 60.
Hopper 52 may have an open top to receive paving material M from any known mechanism, for example, from a dump truck. Hopper 52 may also have an open bottom to allow feeder conveyor 54 and auger 55 to dispense material M out of hopper 52 and onto subgrade S. Hopper 52 may be fixedly integrated into frame 50 of paving machine 12. The side walls of hopper 52 may be fixed or alternatively may be pivotable to allow for a maximum capacity during paving processes and a minimum width during transport.
One or more feeder conveyors 54 may be connected to the bottom of hopper 52. If multiple feeder conveyors are used, they may be placed side-by-side and run parallel to one another. Feeder conveyor 54 may transport paving material M from hopper 52 to a rear of paving machine 12, where paving material M may be dispensed behind paving machine 12 onto subgrade S and moved in front of screed 56 by auger 55.
Screed 56 may be attached at the rear of paving machine 12 and may be configured to level, shape, and/or position paving material M dispensed by feeder conveyor 54. Typically, paving material M may be dispensed via paving machine 12 at an irregular thickness according to the surface profile of subgrade S. The surface profile of the dispensed paving material M may vary inversely with the profile of subgrade S. For example, relatively thinner sections of paving material M may be dispensed over elevated portions of subgrade S and relatively thicker sections of paving material M may be dispensed over depressions in subgrade S. The height of screed 56 may be altered in response to these variations according to mechanisms known in the art.
Paving machine 12 may also include a mixing device 62 configured to mix a supply of capsules 66 with paving material M before screed 56 shapes paving material M. Mixing device 62 may include a capsule hopper 68 and a rate controller 69.
Capsule hopper 68 may be any container configured to temporarily hold a plurality of capsules. Capsule hopper 68 may feed capsules 66 to rate controller 69, which may regulate the flow of capsules 66 into paving material M. Rate controller 69 may regulate the flow of capsules 66 based on, for example, the forward speed of paving machine 12. It should be noted, however, that rate controller 69 may alternatively utilize other mechanisms to dispense capsules 66 or that rate controller 69 may be subject to manual operation by a user, if desired. Because capsules 66 may be mixed into paving material M in a rate-controlled manner, capsules 66 may be substantially evenly distributed within paving material M.
Mixing device 62 may be configured to mix capsules 66 with paving material M in hopper 52 at feeder conveyor 54, or at any location before paving material M reaches screed 56. It should be noted, however, that capsules 66 could alternatively be mixed with paving material M prior to placement into hopper 52, if desired. That is, a paving mixture including paving material M and capsules 66 may be loaded directly into hopper 52. Alternatively, paving material M and capsules 66 may be mixed by auger 55, if desired.
Compactor 16 may include a frame 34, having at least a front compacting drum 36. In the disclosed embodiment, compactor 16 also includes a rear compacting drum 38 coupled to frame 34. Compactor 16 may further include a controller 43. Controller 43 may include an electronic control unit 46. Controller 43 may be in communication with a GPS device 47 and a dye detector 48. Dye detector 48 may be a UV detector, an IR detector, or any other suitable detector for detecting the presence of a dye at the surface of paving material M. Dye detector 48 may include an emitter that emits a detection beam to a particular zone within a detection range of compacted paving material M around compactor 16, and an associated receiver that receives a reflection of that detection beam. Based on characteristics of the reflected beam, a presence or absence of a minimum amount of a dye on a surface of paving material M may be determined. Dye detector 48 may then generate a signal corresponding to a presence or absence of a dye at the surface of a dispensed mixture or paving material, and communicate the signal to controller 43 for subsequent processing. It is noted, however, that dye detector 48 may not be integral with compactor 16. For example, dye detector 48 may be a portable device, if desired.
Referring to FIG. 2, there is shown an exemplary hollow capsule 66. Capsule 66 may include a shell 71 that is at least partially filled with a dye 70. Shell 71 may have a diameter in the range of about 50-1000 microns. However, it should be noted that any other suitable diameter may alternatively be used. Capsules 66 may be designed to have a predetermined crush strength that is exceeded before or when a desired compaction level of paving material M is achieved. That is, a pressure within paving material M acting on capsule 66 may result in a force that exceeds the predetermined crush strength of capsules 66 before or when the desired compaction level of paving material M is achieved. In one example, the predetermined crush strength of capsules 66 may be in the range of about 300-500 kPa, and the desired compaction level may be about 90-97% of a theoretical maximum density. Capsules 66 may therefore remain substantially intact during operations prior to achieving the desired compaction level of paving material M, such as transport, handling, mixing, and an initial compaction of paving material M (i.e., up to the application of the predetermined crush strength to capsules 66). Once the predetermined crush strength is exceeded within paving material M, capsules 66 may fracture and release dye 70. And once the desired compaction level is subsequently achieved within paving material M, a sufficient amount of dye 70 may be forced to a surface of paving material M by a corresponding reduction in voids within the paving material M. It should be noted that the predetermined crush strength of capsules 66 and the desired compaction level of paving material M may alternatively have other values and may be selected based on specifics of the paving application and the paving material.
Dye 70 contained in capsules 66 may be any suitable dye capable of being detected at the surface of paving material M and immiscible with paving material M. Dye 70 may be organic, inorganic, synthetic, and/or naturally-occurring. Dye 70 may further be seen in the visible portion of the electromagnetic spectrum, or may be infrared (IR), near-infrared (NIR), ultraviolet (UV), near-ultraviolet (NUV), or radioactive. It is noted, however, that other suitable dyes capable of detection by the human eye or by dye detector 48 may alternatively be used.
Shell 71 may be made from a material that is not miscible with paving material M. For example, shell 71 may be made of a polymeric agent. Shell 71 may alternatively be made from other suitable materials such as glass, metal, silica, and cement. It should be noted, however, that shell 71 may still alternatively be made of any other suitable material that is not miscible with paving material M. Shell 71 may embody any suitable shape such as a sphere, cube, or oblong shape, if desired.
Referring to FIG. 3, there is shown another exemplary hollow capsule 76 filled with dye 70. Capsule 76 may be substantially similar to capsule 66 described in FIG. 2 except that capsule 76 may not be fully enclosed, and may contain a gap 78. Capsule 76 may at least partially enclose dye 70. Dye 70 may be substantially contained within capsule 76 by a capillary force. That is, particles within dye 70 may have a sufficient capillary attraction toward each other and toward the inner surface of shell 71 to prevent them from spilling out of gap 78 before the desired compaction of paving material M is achieved. Dye 70 may be contained within shell 71 until a force approximately equal to a crush strength of shell 71 is applied to capsule 76.

INDUSTRIAL APPLICABILITY

The disclosed system may be applicable to any paving process where obtaining proper compaction levels of the paving material is important. The system is particularly applicable to paving applications where it is desirable to obtain low-cost, real-time, and/or simple measurements of compaction levels during and after dispensing of the paving material. The disclosed system may not require any computerized equipment. That is, a visual map detectable by an operator without the use of any computerized equipment or electronic sensors may be formed when a visible dye flushes to the surface of the paving material. Additionally, the disclosed system may be usable with any machine. For example, the disclosed system may be used with either old or new paving machines and may be used with either autonomous or manually controlled paving machines. An exemplary paving process will now be described.
There is shown a flowchart 400 in FIG. 4 illustrating a paving process according to an exemplary embodiment. The process of flowchart 400 may begin at Control Block 410, where mixing device 62 of paving machine 12 may mix capsules 66 or 76 with paving material M. As indicated above, mixing may occur at any location within paving machine 12, or may alternatively occur before paving material M is loaded into hopper 52.
From Control Block 410, the process may proceed to Control Block 420 where the combined mixture of paving material M and capsules 66 or 76 may be transported from hopper 52 by feeder conveyor 54 and dispensed at a desired location, such as on subgrade S. Capsules 66 or 76 may be distributed substantially evenly within paving material M. The density of capsules 66 or 76 within paving material M may be selected so that a user can accurately determine the level of compaction for the entirety of a project area such as a roadway, building site, embankment, or the like. Alternatively, capsules 66 or 76 may be dispensed only at specified test locations within paving material M on subgrade S. Still further, capsules 66 or 76 may be distributed randomly within paving material M with sufficient spacing to prevent bunching. Distribution density may be controlled by the release rate of the capsules. That is, due to variation of material flow prior to screed 56, there may be some randomness in distribution density.
The dispensed mixture may then undergo a compacting process at Control Block 430, for example, by compactor 16. Compactor 16 may make one or more passes over a given strip of paving material M dispensed by paving machine 12. Compactor 16 may be operated either via autonomous or operator control.
Both during and after the paving process is performed at Control Block 430, a real-time indication of the compaction level of paving material M may be obtained at Control Block 440 by monitoring for the presence of dye 70 at the surface of paving material M. That is, after the paving process is performed at Control Block 430, the surface of paving material M may be monitored for the presence of dye 70. Surface monitoring may be performed visually by an operator without the use of computerized equipment or electronic sensors when dye 70 is within the visible spectrum. Alternatively, dye detector 48 may be configured to detect visible, infrared, near-infrared, ultraviolet, or near-ultraviolet dyes. Capsules 66 or 76 may only fracture when a predetermined crush strength has been applied to shell 71.
When a pressure force greater than or equal to the predetermined crush strength has been applied to capsules 66 or 76, shell 71 may fracture, and may release dye 70 into paving material M. The predetermined crush strength of shell 71 may be exceeded before a desired compaction level of paving material M is achieved. In this embodiment, fractured capsules 66 or 76 may release dye 70 into an undercompacted paving material M. The void spaces of undercompacted paving material M may be large enough to retain released dye 70. Because dye 70 may be retained within the void spaces of undercompacted paving material M, dye 70 may be prevented from flushing to the surface immediately after release from capsules 66 or 76. Therefore, dye 70 may only flush to the surface of paving material M when paving material M reaches a desired compaction level. That is, the void spaces of paving material M may reduce to a size that is unable to retain released dye 70 when paving material M reaches a desired compaction level.
The presence of dye 70 at the surface of paving material M may correspond to a desired compaction level of paving material M. Because of air voids in paving material M, paving material M may become more compact after each subsequent pass over paving material M by compactor 16. A desired compaction level of paving material M may occur after one or more passes by compactor 16. After desired compaction level such as a compaction level is achieved, it is possible that subsequent passes may result in overcompaction of paving material M which may cause flushing of the binder of paving material M. Monitoring for the presence of a minimum amount of dye 70 at the surface of paving material M may allow a user to determine that a desired compaction level of paving material M has been achieved so that the compacting process may be ended before additional passes by compactor 16 result in overcompaction of paving material M. Monitoring for the presence of dye 70 may include detection of a visible dye at the surface of paving material M by an operator without the use of computerized equipment or electronic sensors. Alternatively, monitoring for the presence of dye 70 may include detection of a minimum amount of dye 70 with dye detector 48.
Based on the presence of a minimum amount of dye 70 at the surface of paving material M at Control Block 440, a determination may be made at Control Block 450 that a desired compaction level of paving material M has been achieved. That is, control of the paving process may occur at Control Block 450. Alternatively, a determination that a desired compaction level of paving material M may be made when dye 70 reaches a minimum density at the surface of paving material M. For example, a minimum density may be visually detected by an operator or may correspond to a minimum light intensity or minimum amount of dye 70 detected by dye detector 48. Additionally, compaction level or paving process data sensed by dye detector 48 may be correlated with GPS data from GPS device 47 to monitor, store, and display the sensed data versus time and location. This data may be used to show a contracting agency that the desired compaction level has been reached and that the desired paving process has been performed. If a determination is made that paving material M has reached a desired compaction level, the compacting process may end or compactor 16 may move to a new area at Control Block 460. For example, controller 43 may instruct compactor 16 to move to a new area or stop compactor 16 based on a presence of a minimum amount of dye 70 at the surface of the dispensed mixture; or instruct compactor 16 to continue compacting a current area based on an absence of a minimum amount of dye 70 at the surface of the dispensed mixture. That is, if insufficient dye 70 is present at the surface of paving material M at Control Block 450, the process may return to execute Control Blocks 430-450 until dye 70 is visible or at a minimum intensity detectable by dye detector 48 at the surface of paving material M and paving material M may be deemed to have reached a desired compaction level.
Using the capsules enclosing a dye to determine desired compaction levels of paving materials may allow for accurate determinations without the use of complex and computerized mapping technologies. For example, a visual map of desired compaction levels can be visually identified by an operator without the use of computerized equipment or electronic sensors. Alternatively, dye detector 48 may be retrofit onto older and existing compactors 16 or alternatively, may be a portable device that can be utilized along any existing compaction system.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed paving system without departing from the scope of the disclosure. Other embodiments of the paving system will be apparent to those skilled in the art from consideration of the specification and practice of the paving system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

Claims

What is claimed is:

1. A method of controlling a paving process, comprising:

mixing at least one capsule that at least partially encloses a dye within a paving material;

dispensing the paving material at a desired location;

performing a compacting process on the paving material;

monitoring for a presence of the dye at a surface of dispensed paving material; and

controlling the compacting process based on the presence of the dye.

2. The method of claim 1, wherein monitoring for the presence of the dye includes visually monitoring for detection of a minimum amount of the dye with a dye detector.

3. The method of claim 1, wherein the at least one capsule has a crush strength that is exceeded before or when the dispensed paving material reaches a desired compaction level.

4. The method of claim 3, wherein at least a portion of the dye flushes to a surface of the dispensed paving material when the paving material reaches the desired compaction level.

5. The method of claim 1, wherein controlling the compacting process based on the presence of the dye at a surface of the dispensed paving material includes continuing the compacting process based on an absence of a minimum amount of dye at the surface of dispensed paving material and ending the compacting process based on the presence of at least the minimum amount of dye at the surface of dispensed paving material.

6. The method of claim 1, further including correlating the presence of the dye at the surface of dispensed paving material with GPS data.

7. The method of claim 1, wherein the at least one capsule includes a shell that fully encloses the dye.

8. The method of claim 1, wherein the at least one capsule includes a shell having a gap and the dye is substantially contained within the shell by a capillary force until a force approximately equal to a crush strength of the shell is applied to the at least one capsule.

9. A paving mixture comprising:

a paving material; and

at least one capsule at least partially enclosing a dye.

10. The paving mixture of claim 9, wherein the at least one capsule has a crush strength that is exceeded before or when a desired compaction level of the paving material is reached.

11. The paving mixture of claim 10, wherein the desired compaction level of the paving material is in the range of about 90-97% of a theoretical maximum density.

12. The paving mixture of claim 9, wherein the dye is visible, infrared (IR), near-infrared (NIR), ultraviolet (UV), near-ultraviolet (NUV), or radioactive.

13. The paving mixture of claim 9, wherein the at least one capsule includes a shell that fully encloses the dye.

14. The paving mixture of claim 9, wherein the at least one capsule includes a shell having a gap and the dye is substantially contained within the shell by a capillary force until a force approximately equal to a crush strength of the shell is applied to the at least one capsule.

15. A paving system comprising:

at least one capsule at least partially enclosing a dye;

a paving machine configured to dispense a mixture of paving material and the at least one capsule on a surface; and

a compactor configured to compact the mixture dispensed by the paving machine.

16. The paving system of claim 15, further including:

a dye detector configured to detect a presence of the dye at the surface of the dispensed mixture; and

a controller in communication with the dye detector, the controller configured to:

instruct the compactor to move to a new area or stop the compactor based on the presence of a minimum amount of the dye at the surface of the dispensed mixture; or

instruct the compactor to continue compacting a current area based on an absence of the minimum amount of the dye at the surface of the dispensed mixture.

17. The paving system of claim 15, wherein the at least one capsule has a crush strength below a desired compaction level of the paving material.

18. The paving system of claim 16, further including a GPS device in communication with the controller, the controller being further configured to correlate the presence of the dye at the surface of the dispensed mixture with GPS data from the GPS device.

19. The paving system of claim 15, wherein the at least one capsule includes a shell that fully encloses the dye.

20. The paving system of claim 16, wherein the dye detector is configured to detect visible, infrared (IR), near-infrared (NIR), ultraviolet (UV), near-ultraviolet (NUV), or radioactive dyes.