PAVING PROCESS

Abstract

A pavement paving process including incorporating a rejuvenator in a layer of compacted millings to yield a layer of rejuvenated layer; and compacting a layer of aggregate over the layer of rejuvenated layer to protect the layer of rejuvenated layer and to cause the layer of aggregate to at least be partially infused with the layer of rejuvenated layer.

Claims

1. A pavement paving process comprising: (a) incorporating a rejuvenator in a layer of asphalt millings to yield a layer of rejuvenated asphalt millings; and (b) compacting a layer of aggregate over said layer of rejuvenated asphalt millings to protect said layer of rejuvenated asphalt millings and to cause said layer of aggregate to at least be partially infused with said layer of rejuvenated asphalt millings.

2. The pavement paving process of claim 1, wherein said layer of asphalt millings comprises compacted asphalt millings.

3. The pavement paving process of claim 2, wherein said rejuvenator is configured to be applied at a rate of about 0.05-0.07 gallon per cubic yard of said compacted asphalt millings.

4. The pavement paving process of claim 1, wherein said layer of asphalt millings comprises millings of about 0.5-3.0 inches.

5. The pavement paving process of claim 1, wherein said layer of aggregate comprises crushed stone of about 0.25-3.0 inches.

6. The pavement paving process of claim 5, said crushed stone comprises a stone selected from the group consisting of limestone, granite, basalt, quartz, sandstone and any combinations thereof.

7. The pavement paving process of claim 1, wherein said compacting step is configured to be performed within about 1 hour of the start of said incorporating step and any one of said layer of rejuvenated asphalt millings and said layer of aggregate is disposed at at least about 70 degrees F.

8. The pavement paving process of claim 1, wherein said incorporating step comprises spraying said layer of asphalt millings.

9. A pavement paving process using asphalt millings, said process comprising: (a) incorporating a rejuvenator in a layer of the asphalt millings in a compacted form to yield a layer of rejuvenated asphalt millings, wherein said rejuvenator is configured to be applied at a rate of about 0.06 gallon per cubic yard of the layer of the millings; and (b) compacting a layer of aggregate over said layer of rejuvenated asphalt millings to protect said layer of rejuvenated asphalt millings and to cause said layer of aggregate to at least be partially infused with said layer of rejuvenated asphalt millings.

10. The pavement paving process of claim 9, wherein the asphalt millings comprise millings of about 0.5-3.0 inches.

11. The pavement paving process of claim 9, wherein said layer of aggregate comprises crushed stone of about 0.25-3.0 inches.

12. The pavement paving process of claim 11, said crushed stone comprises a stone selected from the group consisting of limestone, granite, basalt, quartz, sandstone and any combinations thereof.

13. The pavement paving process of claim 9, wherein said compacting step is configured to be performed within about 1 hour of the start of said incorporating step and any one of said layer of rejuvenated asphalt millings and said layer of aggregate is disposed at at least about 70 degrees F.

14. The pavement paving process of claim 9, wherein said incorporating step comprises spraying said layer of the asphalt millings in a compacted form.

15. A pavement paving process using asphalt millings, said process comprising: (a) incorporating a rejuvenator in a layer of compacted millings to yield a layer of rejuvenated layer, wherein said rejuvenator is configured to be applied at a rate of about 0.05-0.07 gallon per cubic yard of asphalt millings; and (b) compacting a layer of aggregate over said layer of rejuvenated layer to protect said layer of rejuvenated layer and to cause said layer of aggregate to at least be partially infused with said layer of rejuvenated layer, wherein said compacting step is configured to be performed within about 1 hour of the start of said incorporating step and any one of said layer of rejuvenated asphalt millings and said layer of aggregate is disposed at at least about 70 degrees F.

16. The pavement paving process of claim 15, wherein the asphalt millings comprise millings of about 0.5-3.0 inches.

17. The pavement paving process of claim 15, wherein said layer of aggregate comprises crushed stone of about 0.25-3.0 inches.

18. The pavement paving process of claim 17, said crushed stone comprises a stone selected from the group consisting of limestone, granite, basalt, quartz, sandstone and any combinations thereof.

19. The pavement paving process of claim 15, wherein said incorporating step comprises spraying said layer of compacted millings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order that the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0017] FIG. 1 is a diagram depicting a collection of substrates and substance useful in the construction of a pavement using a present paving process.

[0018] FIGS. 2A-2E represent a series of figures useful for illustrating a present paving process.

[0019] FIG. 2A is a diagram depicting a layer of asphalt millings having been laid and is being compacted.

[0020] FIG. 2B is a diagram depicting a rejuvenator being applied to the compacted layer of asphalt millings shown in FIG. 2A.

[0021] FIG. 2C is a diagram depicting a layer of aggregate having been applied to the sprayed and compacted layer of asphalt millings shown in FIG. 2B.

[0022] FIG. 2D is a diagram depicting the layer of aggregate shown in FIG. 2C is being compacted against the sprayed and compacted layer of asphalt millings.

[0023] FIG. 2E is a diagram depicting the layer of aggregate shown in FIG. 2D having been compacted against the sprayed and compacted layer of asphalt millings shown in FIG. 2D.

[0024] FIG. 3 is a diagram depicting a layer of aggregate having been compacted against a sprayed and compacted layer of asphalt millings.

[0025] FIG. 4 is a summary of a present paving process.

PARTS LIST

[0026] 2pavement [0027] 4asphalt millings [0028] 6rejuvenator [0029] 8aggregate [0030] 10step of laying and compacting millings [0031] 12step of applying rejuvenator [0032] 14step of laying and compacting aggregate [0033] 16applicator [0034] 18direction of travel of applicator [0035] 20compactor [0036] 22direction of travel of compactor [0037] 24infused layer of aggregate and layer of millings

Particular Advantages of the Invention

[0038] As a substitute for an asphalt-based paving process, the present paving process reduces the use of asphalt, reducing or eliminating the part of the paving process that traditionally incurs the highest cost while providing a paved surface suitable for vehicular and heavy equipment traffic.

[0039] Unlike an application of asphalt or asphalt sealer over an aggregate foundation, an application of rejuvenator in asphalt millings allows the rejuvenator to penetrate, flux and co-mingle with the existing asphalt binder of asphalt millings, instead of adding another layer to the substrate, restoring asphalt binder, e.g., maltenes that have been lost due to aging in the asphalt millings. An asphalt rejuvenator penetrates the asphalt well below the surface to chemically revitalize and protect the asphalt binder.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0040] The term about is used herein to mean approximately, roughly, around, or in the region of. When the term about is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term about is used herein to modify a numerical value above and below the stated value by a variance of 20 percent up or down (higher or lower).

[0041] In order to reduce the amount of pavement construction waste and the need for new pavement construction materials, used asphalt is increasingly being recycled and merged in asphalt-producing processes in the form of asphalt millings. Asphalt is a mixture of various sizes of rock and oil as a binder. Asphalt pavements that have been damaged over a period of use can be milled to produce asphalt millings which are typically sorted according to their sizes and used according to certain weight or volume percentages in a reconstituted asphalt mixture. While reconstitution of asphalt millings and new aggregate with an appropriate asphalt binder to form asphalt theoretically can be used to reduce the amount of new aggregate required, this process is fraught with shortcomings in practice. Ideally, asphalt millings should be interspersed evenly with new aggregate and an appropriate asphalt binder to result in asphalt consistent in its quality throughout the mixture. However, in practice, asphalt millings tend to get added to the mixture in clusters or clumps. While it is easy to assume recycled asphalt millings would behave identically or similarly to aggregate, recycled asphalt millings include a used asphalt binder interspersed within the millings which may not be revived in their function as a binder in the reconstituted asphalt mixture, therefore resulting in noticeable differences in appearance and function in the resulting asphalt mixture between the portions of asphalt made with fresh aggregate and portions of asphalt made with asphalt millings. The Applicant discovered a new process in which asphalt millings used therein can be properly rejuvenated with a rejuvenator to provide strength and longevity when combined with a fresh layer of aggregate atop a layer of millings being rejuvenated, thereby prolonging the service life of the pavements constructed from the asphalt millings and removing the need for additional and new asphalt.

[0042] A rejuvenator, as used herein, shall refer to any compositions or materials capable of providing the features in the rejuvenator itself or any materials it interacts with. The purpose of a rejuvenator is to rejuvenate aged asphalt binder and provide a fuel resistant surface. Rejuvenation, as used herein, is defined as an act which significantly lowers viscosity, increases ductility, lowers softening point and increases penetration, without disturbing the asphalt's capacity to bind aggregate and without significantly lowering skid resistance of the asphalt and/or aggregate it interacts with.

[0043] FIG. 1 is a diagram depicting a collection of substrates and substance useful in the construction of a pavement 2 using a present paving process. The pavement paving process includes incorporating a rejuvenator 6 in a layer of compacted millings 4 to yield a layer of rejuvenated or rehabilitated layer; and compacting a layer of aggregate 8 over the layer of rejuvenated layer to protect the layer of rejuvenated layer and to cause the layer of aggregate 8 to at least be partially infused with the layer of rejuvenated layer.

[0044] FIGS. 2A-2E represent a series of figures useful for illustrating a present paving process. FIG. 2A is a diagram depicting a layer of asphalt millings 4 having been laid and is being compacted. FIG. 2B is a diagram depicting a rejuvenator 6 being applied to the compacted layer of millings 4 shown in FIG. 2A. FIG. 2C is a diagram depicting a layer of aggregate 8 having been applied to the sprayed and compacted layer of millings 4 shown in FIG. 2B. FIG. 2D is a diagram depicting the layer of aggregate 8 shown in FIG. 2C is being compacted against the sprayed and compacted layer of asphalt millings 4. FIG. 2E is a diagram depicting the layer of aggregate 8 shown in FIG. 2D having been compacted against the sprayed and compacted layer of millings 4 shown in FIG. 2D.

[0045] First, a layer of asphalt millings 4 is laid down cold (e.g., without external heating) on the ground upon which a pavement is to be constructed or an existing bed of stone foundation as shown in FIG. 2A. Asphalt millings 4 may also be supplied in place when an existing asphalt pavement is recycled in place to reduce or eliminate the amount of new asphalt millings and/or asphalt that need to be supplied. In general, asphalt millings 4 may include broken, milled, fractionated and virgin aggregate depending on the types of materials used in the construction of the existing pavement that is to be reconstructed as the amount of asphalt interspersed in the existing asphalt and the size of the aggregate in the existing asphalt can vary. Once a layer of asphalt millings 4 has been laid and graded, it can then be compacted as shown in FIG. 2A, e.g., with a roller compactor 20, i.e., in a direction 22 of travel of the roller compactor 20. The asphalt millings 4 need not be laid hot although in cold weather applications, millings are preferably be disposed at or near elevated surface or aggregate temperature of at least 70 degrees F. and rising, especially when rapid heat loss can readily occur to the ground and ambient air. The rejuvenator shall be applied only when the existing surface or asphalt millings is dry. When prolonged suitable surface temperature is available, no additional heating of the millings is required. Therefore, the present process of laying asphalt millings during the summer months is usually not as heat energy intensive compared to conventional pavement construction techniques involving asphalt where asphalt disposed at significantly elevated temperatures is essential for paving with asphalt. Compaction of the asphalt millings layer increases the integrity and strength of this layer while allowing the rejuvenator to be applied in the next step as shown in FIG. 2B to percolate through the compacted layer and effectively rejuvenate any spent asphalt therein to again bind the compacted asphalt millings composed essentially of used aggregate and aged binders. In one embodiment, the rejuvenator 6 is applied, e.g., by spraying, at a rate of about 0.05-0.07 gallon per square yard (gsy) of the area covered by compacted asphalt millings. The rejuvenator 6 is again applied in a second pass, e.g., by spraying, at the same rate over the same area of compacted asphalt millings to rehabilitate the RAP fully and properly. Care must be taken to avoid applying the rejuvenator 6 at a rate significantly outside of the range of about 0.05-0.07 gsy in each pass to ensure sufficient rejuvenator 6 is used while reducing over-application of rejuvenator that results in wastes. The rejuvenator 6 is preferably applied with the layer of asphalt millings 4 disposed at temperature of at least about 70 degrees F. In one example, a positive displacement pump capable of pumping low viscosity material at a pre-selected constant pressure of about 0-60 psi is used to deliver the rejuvenator to a sprayer. In one example, the sprayer, moved in direction 18, includes a spray bar and an applicator 16 which maintains proper nozzles a flow which provide the rate of application disclosed elsewhere herein. In one example of a spray bar, the spray bar is hooded to maintain a proper nozzle height.

[0046] Upon application of the rejuvenator 6, an aggregate layer 8 is laid over the layer of millings 4 as shown in FIG. 2C. In one embodiment, the aggregate 8 layer is preferably compacted against the asphalt millings 4 layer within about 1 hour at suitable surface temperature after the rejuvenator 6 has been applied. As the aggregate layer 8 is being compacted over the layer of millings 4 as shown in FIG. 2D, the aggregate layer 8 becomes co-mingled or infused with the millings layer 4 to form an infused layer 24 while the applied rejuvenator disposed below it has the opportunity to rejuvenate the oils, e.g., tar, i.e., an asphalt binder of the spent asphalt, allowing the rejuvenated asphalt binder to percolate upwardly into the aggregate 8 layer to bond with the aggregate. It shall be noted that some of the aggregate becomes mixed with the millings and vice versa as shown in the aggregate 8 materials appearing in the millings 4 layer and millings 4 materials appearing in the aggregate layer 8 as shown in FIGS. 2D and 2E upon compaction. It is this interaction or co-mingling between the layers 4, 8 which gives the resulting product strength and cohesiveness when used in conjunction with the rejuvenator.

[0047] FIG. 3 is a diagram depicting a layer of aggregate 8 having been compacted against a sprayed and compacted layer of asphalt millings 4. It shall be noted that, the extent of infusion of one layer in another depends on their relative sizes. Here, the aggregate 8 layer includes mostly finer-sized crushed stones, e.g., about ?-inch-1.5-inch compared to the size of millings of about 2-inch-3-inch and the infusion of the aggregate 8 layer in the millings 4 layer is limited. The top surface of the compacted aggregate 8 layer appears more uniform with the similarly-sized aggregate without co-mingled millings appearing at the top surface upon compaction of the aggregate 8 layer, therefore resulting in a uniform top layer called a cap.

[0048] Referring back to FIGS. 2D and 2E, it shall be noted that the sizes of the aggregate and the millings are significantly more comparable. For instance, the aggregate 8 layer includes mostly crushed stones, e.g., about 1.5-inch-3-inch compared to the size of asphalt millings of about 2-inch-3-inch. Crushed stones can include, but not limited to, limestone, granite, basalt, quartz and sandstone, etc., or any combinations thereof. The decision to use a particular type of aggregate lies mostly with the type of aggregate available or quarried locally. Upon installation of the aggregate layer or the completion of the present paving process, the amount of time for the rejuvenator to cure within the asphalt millings 4 and aggregate 8 mix depends primarily on the mix temperature and it can range anywhere from about 24-72 hours with the lower cure time corresponding to higher mix temperatures.

[0049] FIG. 4 is a summary of a present paving process. A layer of millings is first laid and compacted as shown in step 10. A rejuvenator is then applied to or incorporated into the compacted asphalt millings as shown in step 12. A layer of aggregate is then laid and compacted against the layer of compacted asphalt millings which has received the rejuvenator as shown in step 14 to result in an integrated layer adhered together by compaction and with the aid of rejuvenated binders.

[0050] The detailed description refers to the accompanying drawings that show, by way of illustration, specific aspects and embodiments in which the present disclosed embodiments may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice aspects of the present invention. Other embodiments may be utilized, and changes may be made without departing from the scope of the disclosed embodiments. The various embodiments can be combined with one or more other embodiments to form new embodiments. The detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, with the full scope of equivalents to which they may be entitled. It will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations of embodiments of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive, and that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Combinations of the above embodiments and other embodiments will be apparent to those of skill in the art upon studying the above description. The scope of the present disclosed embodiments includes any other applications in which embodiments of the above structures and fabrication methods are used. The scope of the embodiments should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.