Asphalt coating composition and asphalt coating method

Abstract

The present disclosure includes systems and methods for applying a coating system to a surface. An exemplary method includes applying an asphalt emulsion to a surface at a rate of approximately 0.12 to 0.20 gallons per square yard, the asphalt emulsion including Gilsonite, at least a portion of which includes an asphalt blend modified to have a positive charge, one or more polymers, and one or more surfactants. The method may also include applying fine aggregate onto the asphalt emulsion. The fine aggregate may be applied at a rate of approximately 2.5 pounds per square yard. In such an embodiment, the asphalt emulsion may be applied at a rate of approximately 0.18 gallons per square yard, and the asphalt emulsion may include approximately 56% solid asphalt residue by weight. In another embodiment, the fine aggregate may be applied at a rate of about 1.25 pounds per square yard, the asphalt emulsion may be applied to the pavement at a rate of about 0.17 gallons per square yard, and the asphalt emulsion may comprise about 37% solid asphalt residue by weight of the asphalt emulsion.

Description

Technical Field

[0001] [Cross-Reference to Related Applications] This application claims priority to U.S. Application No. 17 / 937,213 filed on September 30, 2022, the content of which is hereby incorporated by reference in its entirety for all purposes as if fully set forth in the present specification.

[0002] [Technical Field] The present disclosure relates to a coating system for asphalt pavement and a method related thereto.

Background Art

[0003] Asphalt pavement is a composite material comprising mineral aggregate and asphalt binder, which cures to form a rigid surface. Asphalt pavement degrades over time due to oxidation of the asphalt binder, heavy loads, and variations in climatic conditions. One method for restoring or repairing degraded asphalt pavement is to remove the existing pavement and replace it with newly prepared or recycled pavement. However, removal and replacement are costly and wasteful. Nevertheless, there exist asphalt pavement repair products used to repair pavement surfaces.

[0004] Typical asphalt repair products comprise a coating composition, such as a uintaite-asphalt composition, and aggregate. In general, this composition can be spray-applied to asphalt pavement, after which the aggregate is applied over the composition using a spreader or other similar device. However, there are various variations in the methods by which the composition and aggregate can be prepared. The components of the composition, the type of aggregate, and its application rate (gals. / yd 2 and / or lbs. / yd 2All of these can be modified to achieve specific performance targets. Furthermore, in some cases, the coating composition and aggregate can be combined and then applied to the pavement. However, in many cases, the specific product to be applied to the pavement and its application rate depend on the method used for paving.

[0005] The asphalt paving industry has two somewhat independent sectors: aviation and road. Aviation pavement, such as the pavement used in the construction of airport runways, has greater demands compared to road pavement. In the case of aviation pavement, safety is paramount, construction work and schedules are difficult to meet, the challenges are more serious, and addressing them is more expensive. Furthermore, aviation pavement is used to support aircraft, while road pavement is used for cars and trucks. Also, these two types of pavement deteriorate differently over time. In general, the requirements for airport pavement (e.g., performance requirements, specifications, quality control systems, etc.) are generally stricter and more extreme than those for pavement used for roads.

[0006] Conventional road asphalt repair surface treatments are not always suitable for airport pavement. Typical road treatments designed for durability beyond 3-5 years are typically unsuitable for the required aerospace pavement. As road treatments increase over time, safety performance issues arise, such as the generation and increase of foreign object debris (FOD), and good friction properties deteriorate. Even if airport asphalt pavement has been treated in the past with a common Untight-asphalt coating or other repair coating, once its surface condition deteriorates, it must be retreated to maintain minimum safety requirements. Without further treatment, the pavement will require much more extensive and costly destructive restoration. Conventional road treatments can be modified to improve road conditions and enhance friction properties, thereby addressing the aforementioned safety issues. Unfortunately, such treatments (or procedures) have a relatively short lifespan, lasting 2-5 years or less. Other more substantial (heavily applied) asphalt repair treatments can offer a longer service life than 3-5 years. However, these substantial treatments are not well-suited to the requirements of airport paving applications. There is a lack of coating systems that can be applied at relatively heavy rates and are suitable for both road and aerospace paving, while offering an extended and beneficial service life. [Overview of the project]

[0007] This disclosure includes a method for applying (or coating) a coating system to a surface. In one or more embodiments, the method includes spraying an asphalt emulsion (or asphalt emulsion) onto the surface at a rate of about 0.12 to 0.20 gallons / square yard, wherein the asphalt emulsion comprises an asphalt blend, at least a portion of which is modified to have a positive charge, one or more polymers, and one or more surfactants. The method may include applying (or coating) fine aggregate to the stable cationic emulsion applied to the surface. In one embodiment, the fine aggregate may be applied at a rate of about 2.5 pounds / square yard. In such an embodiment, the asphalt emulsion may be sprayed onto the surface at a rate of about 0.18 gallons / square yard, wherein the asphalt emulsion may contain about 56% by weight of solid asphalt residue (or solid residue). In another embodiment, the fine aggregate may be applied at a rate of about 1.25 pounds / square yard. In another embodiment, the asphalt emulsion may be sprayed at a rate of about 0.17 gallons / square yard, and the asphalt emulsion may contain about 37% by weight of solid asphalt residue.

[0008] In one embodiment, an asphalt emulsion containing about 37% by weight of solid asphalt residue may be sprayed onto a surface at a rate of about 0.12 gallons / square yard, and fine aggregate may be applied at a rate of about 0.6 pounds / square yard. In another embodiment, an asphalt emulsion containing about 37% by weight of solid asphalt residue may be sprayed onto a surface at a rate of about 0.20 gallons / square yard, and fine aggregate may be applied at a rate of about 2.0 pounds / square yard.

[0009] The disclosure also includes a system (or scheme) for treating pavement. In one embodiment, the system may include an asphalt emulsion. The asphalt emulsion may include an asphalt blend comprising a first asphalt naturally containing a large amount of nitrogen-containing polar resin, the asphalt blend modified so that at least a portion of the nitrogen-containing polar resin is positively charged, one or more polymers, and one or more surfactants. The system may include aggregate material for application to pavement coated with the asphalt emulsion. The application rate of the asphalt emulsion may be about 0.12 to 0.20 gallons / square yard. At least a portion of the nitrogen-containing polar resin may be pyrrole. An acid modifier may be added in an amount such that the pH of the asphalt emulsion is 6.5 or less. In another embodiment, an acid modifier may be added in an amount such that the pH of the asphalt emulsion is 5.0 or less. The acid modifier may include hydrochloric acid. The acid modifier may include polyphosphate.

[0010] In one embodiment, the aggregate of such a system may be sized such that more than 98% of the aggregate material passes through a No. 14 sieve and 15% to 45% of the aggregate material passes through a No. 30 sieve. In another embodiment, the first asphalt may be gilsonite.

[0011] In one embodiment, the asphalt emulsion may contain about 56% by weight of solid asphalt residue and may be applied to the pavement at a rate of about 0.18 gallons / square yard, and the aggregate material may be applied at a rate of about 2.5 pounds / square yard.

[0012] In another embodiment, the asphalt emulsion may contain about 37% by weight of solid asphalt residue and may be applied to the pavement at a rate of about 0.17 gallons / square yard, and the aggregate material may be applied at a rate of about 1.25 pounds / square yard.

[0013] In another embodiment, the asphalt emulsion may contain about 37% by weight of solid asphalt residue and may be applied to the pavement at a rate of about 0.12 gallons / square yard, and the aggregate material may be applied at a rate of about 0.6 pounds / square yard.

[0014] In another embodiment, the asphalt emulsion may contain about 37% by weight of solid asphalt residue and may be applied to the pavement at a rate of about 0.2 gallons / square yard, and the aggregate material may be applied at a rate of about 2.0 pounds / square yard. [Brief explanation of the drawing]

[0015] The above-mentioned and other features of this disclosure will be more readily apparent from the following description in conjunction with the accompanying drawings. Understanding that these drawings illustrate only a limited number of aspects in accordance with this disclosure and are therefore not intended to limit its scope, this disclosure will be described more specifically and in detail with the accompanying drawings. Those skilled in the art will understand that certain features are optional and that features or aspects of one embodiment can be used or combined with other features highlighted in another embodiment. Furthermore, each and all of the illustrated and described embodiments are not necessarily required, and rather various embodiments are illustrated and / or described as features of potential embodiments that may be included.

[0016] [Figure 1] Figure 1 is an illustrative graph showing the coefficient of friction in pavement sections where bleeding or flushing occurs, creating extremely slippery and dangerous areas. [Figure 2] Figure 2 is a graph showing friction data on the road's wheelpath, provided as a control sample. It represents a deteriorated but "appropriate" road, exhibiting typical but acceptable friction characteristics. [Figure 3] Figure 3 is a graph showing friction data for roadways, and it shows the friction measurement results for an existing coating system less than one month after application (or coating). [Figure 4]Figure 4 is a graph showing friction data for the roadway, and it shows the friction measurement results of an existing coating system 11 months after application (or coating). [Figure 5] Figure 5 is a graph showing friction data for a roadway, illustrating the friction measurement results of a coating system according to one embodiment of this disclosure 11 months after application (or coating). [Figure 6] Figure 6 is a graph showing friction data for a roadway, illustrating the friction measurement results of a coating system according to one embodiment of this disclosure less than one month after application (or coating). [Figure 7] Figure 7 is a graph showing friction data for the roadway, illustrating the friction measurement results of a coating system according to one embodiment of this disclosure 11 months after application (or coating). [Modes for carrying out the invention]

[0017] In this detailed description, reference is made to the accompanying drawings, which form part of this detailed description. In the drawings, similar symbols typically indicate similar components unless otherwise noted. The illustrative examples, drawings, and potential points of novelty described in this detailed description are not intended to limit. Other embodiments may be used and other modifications may be made without departing from the concepts or scope of the matters described herein. It is readily apparent that the embodiments of this disclosure may be arranged, substituted, combined, and designed in a wide variety of configurations as described herein and shown in the drawings, all of which are clearly conceivable and constitute part of this disclosure.

[0018] In one aspect of this disclosure, an asphalt emulsion composition for coating a paved surface is provided. In another aspect of this disclosure, an asphalt emulsion composition and aggregate for coating a paved surface is provided. In another aspect of this disclosure, a method for producing an asphalt emulsion composition for coating a paved surface is provided. In another aspect of this disclosure, a method for applying (or coating) an asphalt emulsion and / or aggregate to a paved surface is provided.

[0019] Certain tests and methods for characterizing asphalt pavements, in particular aged or degraded asphalt pavements, are known. Pavements can be evaluated according to the pavement condition index. Roads and parking lots can utilize the pavement condition index in accordance with ASTM D6433-20. Airport tarmacs can utilize the pavement condition index in accordance with ASTM D5340-20. The pavement condition index can be evaluated in the range of 0 to 100. An index score of 85 to 100 can be regarded as good, an index score of 70 to 85 can be regarded as satisfactory, an index score of 55 to 70 can be regarded as fair, and an index score of 40 to 55 can be regarded as poor. Pavements falling into the "poor" category are highly undesirable and impede traffic. The lower the score, the worse the condition of the pavement.

[0020] Accordingly, asphalt pavements can be characterized according to the pavement condition index. However, pavements can also be characterized according to surface density, porosity, texture, water permeability, traffic volume, traveling speed, climate, weather, temperatures normally experienced, snow and ice removal processes, cleaning processes, whether the pavement has previously undergone surface treatment, and the like.

[0021] Characterization of asphalt pavements may take into account the typical use of the pavement as well as the physical conditions of the pavement, and this characterization can convey to those skilled in the art methods for treating the pavement to make the pavement safer or to have generally more desirable properties. Examples of pavement treatments include fog seal treatment (applying asphalt emulsion to the pavement), slurry treatment (applying asphalt emulsion containing slurry-like aggregate), chip seal treatment (sequentially applying layers of asphalt emulsion and crushed stone chips), microsurfacing (similar to slurry treatment), scrub seal (a treatment similar to chip seal, in which asphalt emulsion is rubbed into damaged portions of the pavement), or sequential combinations of treatments (e.g., performing a slurry treatment after a scrub seal). Various asphalt treatments may use asphalt emulsions having different properties, and the selection of which treatment to use may utilize the properties of the asphalt pavement to be treated.

[0022] However, it has been observed that many existing treatments have certain drawbacks. For example, some treatments have the problem of negative primary impacts or negative effects, and these effects become apparent within a very short period of time after the treatment. Negative primary impacts may include improper breakage and curing, the occurrence of extremely slippery pavement or "black ice" due to over-application of asphalt emulsion, and delamination of the new treatment in a short period of time due to over-application of aggregate.

[0023] In addition, many existing treatments may suffer from negative secondary impacts, and these impacts become apparent over time. Negative secondary impacts may include bleeding or flushing, which results in a thin film of asphalt or oil appearing on the surface, making the pavement extremely slippery, reducing friction over time, and causing densification of the pavement or rutting of the roadway surface. The decrease in surface friction properties can be observed in Figure 1, as measured by the coefficient of friction on pavement portions that have undergone bleeding or flushing. Bleeding or flushing can significantly reduce surface friction and result in hazardous areas of the road.

[0024] Even when it is determined that the characteristics of the pavement or a portion of the pavement need to be adjusted in an existing process, adjusting specific parameters can be difficult, if not impossible. For example, slurry and microsurfacing processes cannot be adjusted by the amount of aggregate after the process is prepared; the only adjustable element is the application ratio. Such limitations result in a suboptimal process for the pavement or a portion of it, potentially leading to negative primary or secondary effects. Furthermore, while chip seals may be adjustable by the application ratio of asphalt emulsion and aggregate, they may adhere to specific minimum values ​​for each, which can also result in negative primary or secondary effects.

[0025] The negative primary and secondary effects are not insignificant. For example, fog sealant treatment was applied to a section of asphalt road in Maine. Negative primary and secondary effects (one or more of reduced friction, bleeding, or over-application of asphalt emulsion) occurred, and the treated pavement became slippery, which was determined to have caused a traffic accident. Following the accident, the Maine Department of Transportation suspended the statewide fog sealant treatment program due to safety concerns. An article published in the Morning Sentinel on December 2, 2019, titled "Maine to stop using certain road sealant on travel lanes after dangerous road conditions reported," reports on the Maine Department of Transportation's decision to stop using fog sealant on roads. This was due to a bleeding event occurring in a section of road treated with fog sealant, where the fog sealant did not penetrate deeply enough into the pavement, resulting in a "glassy surface" and causing numerous collisions.

[0026] Aspects of the present disclosure provide pavement surface treatments that mitigate negative primary effects, negative secondary effects, or both. To mitigate such effects, aspects of the present disclosure adjust one or more of the following: the amounts of solids and water in the asphalt emulsion, the application rate of the asphalt emulsion, and the application rate of aggregate. Additionally or alternatively, aspects of the present disclosure may be suitable for treating densified asphalt pavement in specific portions of pavement, such as roadways.

[0027] With regard to asphalt pavements, including both airport and road pavements, there is a range of pavement properties in which existing surface treatments can result in over-application of asphalt emulsion, or exhibit similar negative primary or secondary effects. For example, if the pavement surface is compacted (e.g., average surface texture (or unevenness) of approximately 2 mm or less), relatively dense (e.g., roadways), and / or has relatively low voids and permeability, existing treatments may not penetrate the pavement surface sufficiently. In such cases, over time, and due to traffic, the surface treatment itself may not penetrate the pavement surface, but rather increase its density. In such cases, existing surface treatments can initially improve properties, including frictional properties. For example, improved frictional properties may include higher friction measurements or higher coefficients of friction. However, over time, existing surface treatments may degrade pavement properties, and suboptimal pavement treatments may become entrenched. For example, existing surface treatments may initially show increased friction coefficient measurements, but these measurements may decrease over time as a result of increased treatment density and the fixation of a much lower friction coefficient. This fixed pavement surface can thus become more slippery. In certain coatings (e.g., roads), friction measurements may be below optimal. In other coatings (e.g., airport pavement), friction measurements may be unacceptably low. Even on roads, particularly densely paved sections with existing treatments can subsequently become so densely packed that the friction coefficient becomes extremely low and unsafe.

[0028] Aspects of this disclosure provide surface treatments (or treatment agents) based on (or utilizing) asphalt emulsion, the surface treatments comprising a higher proportion of water and / or other non-asphalt liquids than existing surface treatments. Such treatments may exhibit significantly improved pavement properties with respect to high-density pavements, both immediately after treatment and over a long period after treatment. In one embodiment, such treatments may provide treated pavements having relatively high coefficient of friction measurements, both immediately after treatment and at least 11 months after treatment.

[0029] In one aspect of this disclosure, an improved asphalt emulsion is provided. In one aspect based on this disclosure, the asphalt emulsion may contain about 35% to about 50% by weight of solid asphalt residue. In another aspect, the asphalt emulsion may contain about 37% by weight of solid asphalt residue. In another aspect, the asphalt emulsion may contain about 1.75% by weight of polymer (undiluted) of the emulsion. In another aspect, the asphalt emulsion may contain about 38.25% by weight of solid asphalt residue. In another aspect, the asphalt emulsion may contain about 40% by weight of solid asphalt residue.

[0030] In one embodiment, the asphalt blend before emulsification may contain gilsonite. Approximately 20% by weight of the asphalt blend may contain gilsonite.

[0031] In one aspect of this disclosure, the improved asphalt emulsion may be applied to the pavement surface treatment at a rate of approximately 0.12 to approximately 0.20 gallons / square yard. In another aspect of this disclosure, the improved asphalt emulsion may be applied to the pavement surface treatment at a rate of approximately 0.15 to 0.18 gallons / square yard. In yet another aspect of this disclosure, the improved asphalt emulsion may be applied to the pavement surface treatment at a rate of approximately 0.17 gallons / square yard.

[0032] In one embodiment of this disclosure, aggregates such as fine aggregates may be applied to the pavement surface treatment at a rate of approximately 0.6 to approximately 2.0 pounds per square yard. In another embodiment of this disclosure, aggregates such as fine aggregates may be applied to the pavement surface treatment at a rate of approximately 1.0 to approximately 1.5 pounds per square yard. In yet another embodiment of this disclosure, aggregates such as fine aggregates may be applied to the pavement surface treatment at a rate of approximately 1.25 pounds per square yard.

[0033] In one aspect of this disclosure, the pavement surface treatment may include treating the pavement by uniformly applying (or coating) an asphalt emulsion to the entire pavement surface at a rate of 0.12 gallons / square yard, and then applying fine aggregate on top of the asphalt emulsion at a rate of 0.6 pounds / square yard. In one aspect of this disclosure, the pavement surface treatment may include treating the pavement by uniformly applying an asphalt emulsion to the entire pavement surface at a rate of 0.20 gallons / square yard, and then applying fine aggregate on top of the asphalt emulsion at a rate of 2.0 pounds / square yard. In one aspect of this disclosure, the pavement surface treatment may include treating the pavement by uniformly applying an asphalt emulsion to the entire pavement surface at a rate of 0.17 gallons / square yard, and then applying fine aggregate on top of the asphalt emulsion at a rate of 1.25 pounds / square yard.

[0034] The asphalt emulsion according to this disclosure may include an asphalt blend containing gilsonite. In another embodiment according to this disclosure, the gilsonite in the asphalt blend of the asphalt emulsion is modified (or altered) to have a positive charge (for example, in the presence of an acid or in a low pH environment). In one example, the gilsonite may be included as asphalt (i.e., not as a fraction, distillate, or derivative), and a modifier such as an acid may impart a positive charge to one or more nitrogen-containing portions (including pyrrole). An example of an acid that may be used is hydrochloric acid. Another example of an acid that may be used is polyphosphate. The gilsonite may have a relatively large amount of nitrogen-containing portions. The gilsonite thus modified can impart a cationic effect to the asphalt emulsion without the need for a cationic surfactant.

[0035] Gilsonite is a naturally occurring asphaltite hydrocarbon mineral resin. Gilsonite is a unique composition known to be difficult to incorporate into asphalt emulsions. Gilsonite is a combination of various molecules, which act in a wide variety of ways in asphalt compositions. Gilsonite contains a relatively large number of polar components and resins. For this reason, gilsonite can solvate asphaltenes, which are typically present in asphalt cement. In one embodiment, lowering the pH of the emulsion to an acidic state with the presence of a modifier such as an acid activates one or more nitrogen moieties (such as pyrrole), causing them to become positively charged N+ on the surface of gilsonite-asphalt droplets. Thus, a portion of gilsonite has a positive or partial positive charge. This allows gilsonite to share the ability to behave in accordance with cationic surfactants without the need to add cationic surfactants themselves to the asphalt emulsion. Additionally, the positive or partial positive charge of gilsonite can also act as an adhesive.

[0036] Asphalt can be described as a colloidal system containing various components. For example, asphalt may contain asphaltenes, aromatic compounds, resins, and oily / waxy saturated materials among other components. In most cases, hard asphaltenes are surrounded (solvated) by aromatic compounds, resins, oily / waxy saturated materials, etc.

[0037] The emulsion may contain one or more polymers. The polymers can be used to enhance the durability and toughness of the finished coating system and to help retain fine aggregate material in the coating applied to the pavement. Examples of polymers or copolymers include those that help impart desired properties to the asphalt emulsion residue, for example, by providing a stress-absorbing layer that adheres strongly to the underlying pavement, a non-stick surface, or a polymer that is non-expandable. In one example, the polymer may include a combination of polymers and copolymers such as acrylic, styrene-butadiene rubber, or a combination thereof. The polymer or multiple polymers may constitute about 0.5% to about 5.0% by weight of the emulsion.

[0038] Examples of acrylic polymers or copolymers may include those derived from acrylate monomers. Acrylic monomers may be based on, for example, (meth)acrylic acid, (meth)acrylic acid esters, (meth)acrylamide, (meth)acrylonitrile, and derivatives of these acrylate monomers. Examples of (meth)acrylic acid esters include, but are not limited to, alkyl and hydroxyalkyl esters, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, isobornyl (meth)acrylate, and longer-chain alkyl (meth)acrylates, such as ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, and stearyl (meth)acrylate. Derivatives of (meth)acrylamide include, but are not limited to, alkyl-substituted (meth)acrylamides, such as N,N-dimethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, t-butyl(meth)acrylamide, N-octyl(meth)acrylamide, and longer-chain alkyl(meth)acrylamides, such as N-lauryl(meth)acrylamide and N-stearyl(meth)acrylamide. Acrylic polymers also include polymers commonly known as acrylics, acrylate polymers, polyacrylates, or acrylic elastomers. Acrylate polymers belong to a group of polymers generally called plastics, while acrylic elastomers are a general term referring to a type of synthetic rubber whose main component is alkyl acrylate (e.g., ethyl ester or butyl ester).

[0039] Examples of copolymers may include polymers derived from polyolefins such as vinyl acetate, vinyl chloride, vinylidene chloride, styrene, substituted styrene, butadiene, unsaturated polyester, and ethylene. In some embodiments, the acrylic copolymer is derived from acrylate monomers and mixtures thereof and polymerized with styrene or ethylene. In yet another embodiment, the acrylic copolymer is derived from butyl acrylate and copolymerized with styrene or ethylene. In yet another embodiment, the copolymer is acrylonitrile butadiene.

[0040] In one embodiment, the asphalt emulsion may contain one or more surfactants to establish stability, viscosity, and other properties during storage, transport, application, curing, and hardening. The surfactants may promote short-term and long-term strengthening of the polymer binder in the pavement. Preferably, the surfactants are non-cationic surfactants.

[0041] The surfactant may be a nonionic surfactant and / or an amphoteric surfactant. However, in most cases, emulsions do not contain cationic surfactants due to their adverse effect on emulsion stability and for reasons explained elsewhere in this disclosure. Therefore, amphoteric surfactants and / or nonionic surfactants are preferred over cationic surfactants. Amphoteric surfactants and / or nonionic surfactants shorten the break time / cure time of the emulsion when sprayed on pavement. Amphoteric surfactants are surfactants that can be cationic at low pH and anionic at high pH, ​​while nonionic surfactants have no characteristic charge. In contrast, typical cationic surfactants such as aliphatic alkylamines are always cationic. Cationic surfactants have a strong positive charge except at very high pH.

[0042] Examples of amphoteric surfactants may include alkoxylated alkylamines, betaines, and imidazolinium derivatives. Examples of nonionic surfactants may include ethoxylated compounds and esters, such as ethoxylated aliphatic alcohols, ethoxylated fatty acids, sorbitan esters, ethoxylated sorbitan esters, ethoxylated alkylphenols, ethoxylated aliphatic amides, glycerin fatty acid esters, alcohols, alkylphenols, and mixtures thereof. In one example, a noncationic surfactant may include nonylphenol ethoxylate or ethoxylated alcohol.

[0043] In one embodiment, one or more surfactants may constitute about 0.25% to about 4.0% by weight of the emulsion. In one example, the surfactant constitutes 0.25% to about 2.5% by weight of the emulsion. Furthermore, an amphoteric surfactant constitutes about 0.25% to about 2.0% by weight of the emulsion. A noncationic surfactant may constitute about 0.25% to about 4.0% by weight of the emulsion. In one example, the noncationic surfactant constitutes 0.375% to about 2.0% by weight of the emulsion.

[0044] In one embodiment, the asphalt emulsion may contain a modifier sufficient to charge the gilsonite contained in the asphalt emulsion. In one example, an acid is added to the asphalt emulsion to lower the pH to less than about 6.5. In another example, an acid is added to the asphalt emulsion to lower the pH to less than about 5.0. In one example, the modifier may be an acid present in an amount of about 0.025 to about 1.5% by weight of the emulsion. In one example, the modifier may be hydrochloric acid.

[0045] Additionally or optionally, the asphalt emulsions provided herein may contain any other additives to modify the properties of the emulsion with respect to the intended use, application method and storage conditions. These include, for example, mineral salts, thickeners, stabilizers, antifreeze agents, adhesion promoters, fungicides, and pigments.

[0046] A pavement surface treatment (agent) according to one or more embodiments of the present disclosure may include aggregate or fine aggregate material. The fine aggregate material may include, but is not limited to, crushed chert, quartzite, or carbonate. Other types of fine aggregate may be used in the same manner. The fine aggregate may be dry, clean, firm, durable, and have an angular shape and a highly textured surface (or rough surface). The fine aggregate material may be derived from taconite ore. In one example, the fine aggregate may contain at least 50% by weight of silicon dioxide and about 5% by weight or less of calcium oxide.

[0047] In embodiments of this disclosure, fine aggregate may be applied to the pavement surface after the asphalt emulsion. As the emulsion hardens and curing progresses, the fine aggregate can be embedded and sufficiently bonded within the asphalt emulsion. The fine aggregate can improve the frictional properties of the treated pavement surface. In embodiments, the fine aggregate may have the classification boundaries shown in Table 1 when tested according to ASTM C136. Furthermore, exemplary fine aggregate materials may include the properties shown in Table 2 below.

[0048] Table 1. Particle size of fine aggregate material [Table 1]

[0049] Table 2. Characteristics of fine aggregate [Table 2]

[0050] Aspects of this disclosure include a method for producing an asphalt emulsion. First, the method may include mixing gilsonite with asphalt cement. This mixing may be carried out using a standard vat mixer or similar. This mixing step may include adding any diesel fuel, such as atmospheric pressure diesel fuel, to the asphalt blend. The diesel fuel can help the emulsion penetrate into the underlying pavement. Next, any chemical substance may be added to the asphalt blend. This chemical substance can be used to help melt and mix the gilsonite in the asphalt blend. The asphalt blend composition may be exposed to a temperature of at least about 300 degrees Fahrenheit for a certain period of time. In one example, it may be exposed to a temperature of about 350 degrees Fahrenheit and mixed at that temperature for 24 to 48 hours. In another example, the asphalt blend may be exposed to a temperature of about 400 degrees Fahrenheit and mixed at that temperature for 24 hours.

[0051] The method may involve preparing an aqueous solution containing water, a modifying agent (e.g., an acid), one or more surfactants, and / or one or more other additives. In one example, the acid may be added to and mixed with water or a solution of water and a surfactant (or more surfactants). In one embodiment, the method may feed the asphalt blend and the aqueous solution to an emulsion mill to form an asphalt emulsion. In one embodiment, one or more polymers may be added to the aqueous solution or the asphalt emulsion.

[0052] In one embodiment, the method may involve adding a modifier such as hydrochloric acid to water together with one or more surfactants and / or other additives to form an aqueous solution, which may then be added to an asphalt blend to emulsify the asphalt therein.

[0053] In another embodiment, the method may include adding a modifier such as polyphosphate to the asphalt blend. In this embodiment, polyphosphate may be added to the asphalt blend to modify the gilsonite therein so as to impart a positive or partial positive charge to the nitrogen-containing portion, such as pyrrole. The aqueous solution (if the aqueous solution is not acidic) may then be mixed with the asphalt blend. The modified gilsonite may have surfactant-like properties, and may reduce, if not eliminate, the need to add another surfactant.

[0054] In one embodiment of the present disclosure, the asphalt emulsion of the present disclosure was applied to a high-density paved roadway. The asphalt emulsion contained approximately 56% solid asphalt residue. Friction properties were measured for an untreated control, which was a paved roadway in which the asphalt emulsion was applied at a rate of 0.22 gallons / square yard and fine aggregate at a rate of approximately 2.5 pounds / square yard, corresponding to an existing pavement treatment. The existing pavement treatment was also modified to include the same asphalt emulsion (containing approximately 56% solid asphalt residue) but at a lower rate of 0.18 gallons / square yard and fine aggregate applied at approximately 2.5 pounds / square yard. Thus, the modified treatment applied less asphalt emulsion to a high-density paved roadway. The data in Table 3 were obtained.

[0055] Table 3. Asphalt emulsion containing approximately 56% solid asphalt residue in existing and revised treatment ratios. [Table 3]

[0056] In another aspect of this disclosure, the asphalt emulsion of this disclosure was applied to a paved roadway of a high-density pavement. The asphalt emulsion contained approximately 37% solid asphalt residue, and the water content in the emulsion increased accordingly. A more dilute asphalt emulsion was applied to the high-density roadway at a rate of approximately 0.17 gallons / square yard. Following the application of the asphalt emulsion, fine aggregate was applied at a rate of approximately 1.25 pounds / square yard. Thus, the modified treatment involved applying a further diluted amount of asphalt emulsion to the high-density paved roadway, followed by the application of a smaller amount of fine aggregate compared to the existing pavement treatment. The following data were obtained in Table 4.

[0057] Table 4. Asphalt emulsion containing approximately 37% solid asphalt residue at lower processing rates. [Table 4]

[0058] The data obtained from the test has been graphed and included in the figure. The graph reflects the results of the friction coefficient measurement performed at 60 mph.

[0059] Figure 2 is a graph showing friction data on a roadway, providing a control sample representing a typical road that is deteriorated but in a "fair" condition, exhibiting typical but acceptable friction characteristics. The graph includes the coefficient of friction, μ (mu), on the y-axis 101. The graph includes the distance traveled on the sample pavement on the x-axis 102. The background of the graph includes regions 110 indicating pavement surface conditions that are "excellent" or "good" in terms of friction characteristics, region 120 indicating pavement surface conditions that are "good" or "fair" in terms of friction characteristics, region 130 indicating pavement surface conditions that are "poor" or "unsafe for airfield tarmac," and region 140 indicating pavement characteristics that are "unsafe for roadways." The y-axis 101, x-axis 102, and regions 110, 120, 130, and 140 are similar across the graphs in each figure. Regardless of the above summaries for regions 110, 120, 130, and 140, a coefficient of friction (μ) of 0.72 to 1.00 is considered excellent, μ of 0.52 to 0.71 is considered good, μ of 0.42 to 0.51 is considered average, μ of 0.30 to 0.41 is considered insufficient and unsafe for airport tarmac, and μ below 0.30 is considered unsafe for roads. Despite the above classifications and labeling for regions 110, 120, 130, and 140, higher μ generally represents more favorable surface friction characteristics than lower μ. At very low μ levels, pavement surfaces can become unsafe due to being extremely slippery. Thus, while a μ of 0.45 does not technically position the surface at an "unsafe" level, a μ of 0.60 may be more favorable than a μ of 0.45.

[0060] The control sample without surface treatment in Figure 2 shows a relatively stable pavement surface with a coefficient of friction of 100 along the "good" region 110.

[0061] Figure 3 is a graph showing friction data on a roadway, illustrating the friction measurement results of an existing coating system less than one month after application. The pavement in Figure 2 was treated with an existing surface treatment consisting of an asphalt emulsion with approximately 56% solid asphalt residue applied at a rate of approximately 0.22 gallons / square yard, and fine aggregate applied at a rate of 2.5 pounds / square yard. Less than one month after surface treatment, the measured friction coefficient of 200 indicates a general initial improvement in frictional properties compared to the control, and the 350-400 meter section shows potential initial densification, which may suggest future negative secondary effects.

[0062] Figure 4 is a graph showing friction data for the roadway, illustrating the friction measurement results of the existing coating system 11 months after application. The pavement in Figure 3 was treated with the existing surface treatment, which consisted of an asphalt emulsion with approximately 56% solid asphalt residue applied at a rate of approximately 0.22 gallons / square yard, and fine aggregate applied at a rate of 2.5 pounds / square yard. After 11 months, the measured friction coefficient of 300 indicated a significant deterioration in frictional properties across the pavement, which generally falls into the "poor" and "unsafe for airfield tarmac" range of 130. This may reflect a negative secondary effect due to the increased density of the surface treatment across the pavement.

[0063] Figure 5 is a graph showing friction data on a roadway, illustrating the friction measurement results of a coating system according to one aspect of this disclosure 11 months after application. The pavement in Figure 5 was surface-treated according to one aspect of this disclosure, with an asphalt emulsion containing approximately 56% solid asphalt residue applied at a rate of approximately 0.18 gallons / square yard and fine aggregate applied at a rate of 2.5 pounds / square yard. Approximately one year after surface treatment, the measured friction coefficient of 500 was uniform and within the acceptable "good" or "fair" range of 120, with a mean μ of approximately 0.5. Compared to existing surface treatments, the modified treatment graphed in Figure 5 shows improved friction characteristics without exhibiting significant localized decreases in the friction coefficient that can occur as dangerous slippery areas on the pavement.

[0064] Figure 6 is a graph showing friction data on a roadway, illustrating the friction measurement results of a coating system according to one embodiment of this disclosure less than one month after application. The pavement in Figure 6 was surface-treated according to another embodiment of this disclosure, with an asphalt emulsion containing approximately 37% solid asphalt residue applied at a rate of approximately 0.17 gallons / square yard and fine aggregate applied at a rate of 1.25 pounds / square yard. Less than one month after application, the measured friction coefficient of 600 was extremely uniform throughout the pavement, indicating a very significant improvement in frictional properties.

[0065] Figure 7 is a graph showing friction data on the roadway, illustrating the friction measurement results of a coating system according to one aspect of this disclosure 11 months after application. The pavement in Figure 6 was surface-treated according to another aspect of this disclosure, with an asphalt emulsion containing approximately 37% solid asphalt residue applied at a rate of approximately 0.17 gallons / square yard and fine aggregate applied at a rate of 1.25 pounds / square yard. Approximately one year after surface treatment, the measured friction coefficient of 700 was very uniform throughout the pavement, indicating significantly improved friction characteristics that reflect "excellent" or "good" friction characteristics.

[0066] Therefore, to varying degrees, surface treatments according to the embodiments of this disclosure provide improved frictional properties for pavements, resulting in longer-lasting pavements that are widely found in existing surface treatments and significantly reduce the occurrence of negative secondary effects that may result from increased density of surface treatments.

[0067] While various embodiments are disclosed herein, other embodiments will be apparent to those skilled in the art. The various embodiments disclosed herein are for illustrative purposes only and are not intended to limit the scope. The true scope and concept are as defined in the claims. Furthermore, the disclosure of the present invention may include the following embodiments. (Aspect 1) A method for applying a coating system to a surface, the method is: This includes spraying asphalt emulsion onto the surface at a rate of approximately 0.12 to 0.20 gallons / square yard, and applying fine aggregate on top of the asphalt emulsion applied to the surface. Asphalt emulsion is a) an asphalt blend containing gilsonite, wherein at least a portion of the gilsonite is modified to have a positive charge, b) One or more polymers, and c) A method comprising one or more surfactants. (Aspect 2) The method according to embodiment 1, wherein fine aggregate is applied at a rate of approximately 2.5 pounds / square yard. (Aspect 3) The method according to embodiment 1, wherein fine aggregate is applied at a rate of approximately 1.25 pounds / square yard. (Aspect 4) The method according to embodiment 2, wherein the asphalt emulsion is sprayed at a rate of approximately 0.18 gallons / square yard. (Appendix 5) The method according to embodiment 3, wherein the asphalt emulsion is sprayed at a rate of approximately 0.17 gallons / square yard. (Aspect 6) The method according to embodiment 1, wherein the application of fine aggregate and the spraying of asphalt emulsion are performed using the same application vehicle. (Aspect 7) The method according to embodiment 1, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 56% by weight. (Pattern 8) The method according to embodiment 1, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 37% by weight. (Aspect 9) The method according to embodiment 2, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 56% by weight. (Aspect 10) The method according to embodiment 3, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 37% by weight. (Aspect 11) The method according to embodiment 4, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 56% by weight. (Aspect 12) The method according to embodiment 5, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 37% by weight. (Aspect 13) The method according to embodiment 1, wherein asphalt emulsion is spread at a rate of approximately 0.12 gallons / square yard and fine aggregate is applied at a rate of approximately 0.6 pounds / square yard. (Aspect 14) The method according to embodiment 1, wherein asphalt emulsion is spread at a rate of approximately 0.20 gallons / square yard and fine aggregate is applied at a rate of approximately 2.0 pounds / square yard. (Aspect 15) The method according to embodiment 13, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 37% by weight. (Aspect 16) The method according to embodiment 14, wherein the asphalt emulsion contains solid asphalt residue at a rate of approximately 37% by weight. (Aspect 17) A system for surface treatment of pavement, the system is It comprises an asphalt emulsion and aggregate material for application to pavement coated with the asphalt emulsion, Asphalt emulsion is An asphalt blend comprising a first asphalt naturally containing a large amount of nitrogen-containing polar resin (where at least a portion of the nitrogen-containing polar resin is modified to have a positive charge), One or more polymers, and Contains one or more surfactants, Asphalt emulsion is applied to pavement at a rate of approximately 0.12 to 0.20 gallons per square yard in this system. (Aspect 18) The system according to embodiment 17, wherein at least a portion of the nitrogen-containing polar resin is pyrrole. (Aspect 19) The system according to embodiment 17, further comprising an acid modifier in an amount such that the asphalt emulsion has a pH of 6.5 or less. (Aspect 20) The system according to embodiment 17, further comprising an acid modifier in an amount such that the asphalt emulsion has a pH of 5.0 or less. (Aspect 21) The system according to embodiment 13, wherein more than 98% of the aggregate material passes through sieve No. 14, and 15% to 45% of the aggregate material passes through sieve No. 30. (Aspect 22) The system according to embodiment 13, wherein the first asphalt is gilsonite. (Aspect 23) The system described in embodiment 13, Asphalt emulsion contains approximately 56% solid asphalt residue by weight. Asphalt emulsion is applied to pavement at a rate of approximately 0.18 gallons / square yard, and also, The aggregate material is applied at a rate of approximately 2.5 pounds / square yard in the system. (Aspect 24) The system described in embodiment 13, Asphalt emulsion contains approximately 37% solid asphalt residue by weight. Asphalt emulsion is applied to pavement at a rate of approximately 0.17 gallons / square yard, and also, The aggregate material is applied at a rate of approximately 1.25 pounds / square yard in the system. (Aspect 25) The system described in embodiment 13, Asphalt emulsion contains approximately 37% solid asphalt residue by weight. Asphalt emulsion is applied to pavement at a rate of approximately 0.12 gallons / square yard, and also, The aggregate material is applied at a rate of approximately 0.6 pounds / square yard in the system. (Aspect 26) The system described in embodiment 13, Asphalt emulsion contains approximately 37% solid asphalt residue by weight. Asphalt emulsion is applied to pavement at a rate of approximately 0.20 gallons / square yard, and also, The aggregate material is applied at a rate of approximately 2.0 pounds / square yard in the system.

Claims

1. A method for applying a coating system to a pavement surface, the method is: This includes spraying an asphalt emulsion, diluted to contain approximately 37% solid asphalt residue, onto the pavement surface at a rate of approximately 0.12 to 0.20 gallons / square yard, and applying fine aggregate onto the asphalt emulsion applied to the pavement surface. Asphalt emulsion is a) Asphalt blend containing gilsonite, wherein at least a portion of the gilsonite is modified to have a positive charge, b) One or more polymers, and c) A method comprising one or more surfactants.

2. The method according to claim 1, wherein fine aggregate is applied at a rate of approximately 1.25 pounds per square yard.

3. The method according to claim 1, wherein the asphalt emulsion is sprayed at a rate of approximately 0.18 gallons / square yard.

4. The method according to claim 2, wherein the asphalt emulsion is sprayed at a rate of approximately 0.17 gallons / square yard.

5. The method according to claim 1, wherein the application of fine aggregate and the spraying of asphalt emulsion are performed using the same application vehicle.

6. The method according to claim 1, wherein asphalt emulsion is spread at a rate of approximately 0.12 gallons / square yard and fine aggregate is applied at a rate of approximately 0.6 pounds / square yard.

7. The method according to claim 1, wherein asphalt emulsion is spread at a rate of approximately 0.20 gallons / square yard and fine aggregate is applied at a rate of approximately 2.0 pounds / square yard.

8. The method according to claim 1, wherein the fine aggregate is applied at a rate of about 2.0 to about 0.6 pounds per square yard.

9. The method according to claim 1, wherein the asphalt emulsion further comprises an acid modifier in an amount such that the pH is 6.5 or less.

10. The method according to claim 9, wherein the asphalt emulsion further comprises an acid modifier in an amount such that the pH is 5.0 or less.

11. The method according to claim 1, wherein more than 98% of the aggregate material passes through sieve No. 14, and 15% to 45% of the aggregate material passes through sieve No. 30.

Images