Aqueous bitumen emulsion for the preservation and production of asphalt pavements

Abstract

Aqueous bitumen emulsion for the preservation of asphalt surface layers (100), characterized in that the binder (120) recovered and stabilized from the emulsion has a softening point ring and ball (RuK) according to DIN EN 1427 of more than 60 °C and a penetration at 25 °C according to DIN EN 1426 of less than 25 [0.1 mm].

Description

[0001] The invention relates to an aqueous bitumen emulsion for the preservation of asphalt surface layers.

[0002] Various bituminous systems are known from the prior art for the maintenance of asphalt surface courses. Many of these systems are based on the use of volatile organic solvents to reduce the viscosity of the binder for spray application. However, this is associated with disadvantages regarding environmental compatibility and occupational safety. Aqueous bitumen emulsions are also known as an alternative, which avoid these disadvantages.

[0003] A common disadvantage of all known systems, whether solvent-based or waterborne, is that they are typically based on conventional, soft road construction bitumen. The resulting protective layers exhibit only limited hardness, heat resistance, and mechanical strength. Therefore, they do not offer optimal protection against the high abrasion caused by heavy traffic or high temperatures from solar radiation, thus limiting their preservative effect and extending their service life.

[0004] An expert seeking to create a preservation solution with superior resistance would naturally consider harder binders such as hard bitumen. However, they would encounter an established technical prejudice. Due to its high hardness and viscosity, hard bitumen is considered either impossible or extremely difficult to process into a stable, sprayable aqueous emulsion. This approach is therefore rejected by experts as either impractical or highly problematic. Consequently, it is not apparent from the current state of the art how an easily applicable emulsion with the exceptional mechanical and thermal resistance of hard bitumen can be achieved.

[0005] The invention is therefore based on the objective technical problem of providing a solvent-free, aqueous bitumen emulsion that is easy to apply and produces a protective layer with exceptionally high hardness, heat resistance and wear resistance, which is significantly superior to systems based on standard bitumen.

[0006] This problem is solved by an aqueous bitumen emulsion having the features of claim 1. Advantageous embodiments and further developments of the invention are described in the following dependent claims.

[0007] The invention relates to an aqueous bitumen emulsion particularly suitable for preserving asphalt surface courses. The emulsion is defined by the fact that the binder recovered and stabilized from it exhibits a combination of high hardness and high heat resistance. This is ensured by two measurable parameters: the softening point (ring and ball) must be above 60 °C according to DIN EN 1427, and the penetration at 25 °C must be less than 25 [0.1 mm] according to DIN EN 1426. Compared to the prior art, which only provides qualitative descriptions, this precise technical definition establishes a clear distinction and guarantees objectively verifiable, superior material properties.The high heat resistance prevents the binder from softening under strong sunlight and high summer temperatures, while the high hardness ensures exceptional resistance to mechanical abrasion from vehicle traffic.

[0008] In a particularly advantageous embodiment, the binder contained in the emulsion can be hard bitumen or be obtained from hardened bitumen. This represents the actual technical breakthrough, as the invention succeeds in transforming a material that was considered by experts to be very difficult or even impossible to emulsify into a stable, sprayable aqueous form. This makes the known advantages of hard bitumen—such as extreme durability and wear resistance—accessible for the first time for a simple and environmentally friendly spray application.

[0009] Furthermore, the recovered binder can exhibit an equi-shear modulus temperature of more than 70 °C at a shear modulus of 15 kPa. This rheological characteristic demonstrates the high stiffness and dimensional stability of the binder at practically relevant high temperatures. Such a property is not described in the prior art and results in a significantly lower susceptibility to deformations such as abrasion under heavy traffic loads.

[0010] Another advantageous property is that the emulsion exhibits an adhesion to aggregate particles of more than 70% coverage after 72 hours. This excellent and durable bond between binder and aggregate is crucial to counteracting the primary damage mechanism of asphalt – aggregate loss. Compared to conventional emulsions, this significantly extends the service life of the surface course.

[0011] Furthermore, the emulsion can be solvent-free. This represents a significant advantage over many conventional products, as no volatile organic compounds (VOCs) are emitted during application. This not only protects the environment but also increases occupational safety for personnel and minimizes odor nuisance for residents.

[0012] In particularly preferred embodiments, the properties of the binder can be further refined so that the softening point of the ring and ball is greater than 65 °C, ideally around 67 °C. Simultaneously, the penetration at 25 °C can be less than 20 [0.1 mm], ideally around 18 [0.1 mm]. These specific values ​​define an optimized embodiment of the invention that offers maximum heat resistance and mechanical strength, thus achieving maximum protection for the asphalt surface course.

[0013] A key aspect of the invention lies in the use of the described bitumen emulsion for preserving and extending the service life of an asphalt surface course. The unique properties of the hard bitumen binder create a protective layer that far surpasses the performance of known products. In particular, the emulsion can be used to reduce material wear and the loss of aggregate, thus significantly extending the intervals for costly repairs.

[0014] Especially when applied to open-pore asphalt, the emulsion can be used in such a way that the void content, which is crucial for noise reduction, is not significantly reduced. This solves a key problem in the protection and repair of such specialized pavements, as conventional methods often clog the pores and thus negate the acoustic effectiveness. The invention makes it possible to improve structural integrity while simultaneously maintaining the functional property of noise reduction.

[0015] Furthermore, the invention discloses a novel use of the bitumen emulsion as a barrier layer on a lower asphalt layer. Its purpose is to prevent or reduce the migration of liquid binder from a hot upper asphalt layer applied to it into the lower layer. This problem, which occurs particularly with low-binder base courses, weakens the upper surface course and impairs the overall stability of the road structure. The high heat resistance of the binder according to the invention ensures that the barrier layer remains stable even when in contact with the hot mix of the surface course and reliably fulfills its barrier function, which is not known in the prior art.

[0016] The invention further comprises a method for preserving an asphalt surface course, in which the emulsion according to the invention is applied to the surface, preferably by simple and cost-effective spraying, for example using a spray vehicle. This method combines the high effectiveness of the material with a technically simple application.

[0017] Finally, the invention provides a method for producing a multi-layered asphalt pavement. This method comprises the steps of providing a lower asphalt layer, applying the bitumen emulsion according to the invention to form a stable barrier layer, and subsequently applying a top asphalt layer. Particularly when the lower layer is a low-binder asphalt layer, this method ensures that the final top layer retains its full binder content, thus guaranteeing maximum quality and durability of the entire pavement from the outset.

[0018] The invention described above will be explained in more detail below using an exemplary embodiment.

[0019] They show Fig. 1 a schematic cross-sectional representation of a part of an untreated asphalt surface course, Fig. 2a schematic side view illustrating the application of the emulsion according to the invention, as well as Fig. 3 a schematic cross-sectional representation of the part of the asphalt surface course made of Fig. 1 after treatment with the emulsion according to the invention.

[0020] Fig. Figure 1 shows a schematic cross-section through a portion of an untreated, aged asphalt surface course 100. The asphalt surface course 100 consists of numerous aggregate particles 110 bound together by a binder 120. As a result of aging processes and weathering, the binder 120 has partially deteriorated, creating voids and microcracks 130 between the aggregate particles 110. These microcracks 130 make the structure susceptible to water penetration and accelerate further deterioration and the loss of aggregate particles 110.

[0021] Fig. Figure 2 schematically illustrates the method for applying the bitumen emulsion according to the invention. A spray vehicle 200, equipped with a spray bar 210, drives over the asphalt surface layer 100 to be treated. The emulsion is applied evenly to the surface of the asphalt surface layer 100 from the spray bar 210 in the form of a fine spray mist 220.

[0022] Fig. Figure 3 shows the same section of the asphalt surface course 100 as in Fig. 1, however, after treatment with the emulsion according to the invention and after its breaking. It is clearly evident that the previously in Fig. The microcracks 130 shown in Figure 1 are now filled. This filling, referred to here as hard bitumen filling 140, is the result of the stabilized binder recovered from the emulsion. The hard bitumen filling 140 encapsulates the aggregate particles 110 and the old binder 120, fills the voids, and forms a continuous, resistant protective layer on the surface and in the upper pores of the asphalt surface course 100.

[0023] The function and interaction of the components are determined by comparing the untreated state in Fig. 1 with the treated condition in Fig. 3 clearly. Through the procedural step according to Fig.Following the application of the spray mist 220, which contains the aqueous bitumen emulsion, its low viscosity allows it to penetrate deeply into the porous structure and microcracks 130 of the asphalt surface course 100. After the emulsion breaks down, the high-performance hard bitumen remains as hard bitumen filler 140. This hard bitumen filler 140 firmly bonds with the aggregate 110 and the existing binder 120. It seals the surface against water penetration and protects the underlying material from further oxidation and mechanical abrasion. The aggregate 110 is firmly re-bonded, preventing aggregate loss and significantly extending the service life of the entire asphalt surface course 100.In the alternative application as a barrier layer, the hard bitumen filling 140 formed acts as a stable barrier due to its high heat resistance, preventing the binder of a hot asphalt layer applied above it from migrating into the lower layer.

[0024] Through the described interaction of the components, in particular through the formation of the resistant hard bitumen filling 140, a product is provided that solves the objective technical problem formulated at the outset. An asphalt preservation layer with demonstrably improved properties regarding heat resistance and wear resistance is created, which can simultaneously be used as an effective barrier layer in the composite layer system. REFERENCE MARK LIST 100 Road surface 110 rock grains 120 binders 130 microcracks 140 Hard bitumen filling 200 spray vehicles 210 spray bars 220 spray mist

Claims

[1] Aqueous bitumen emulsion for the preservation of asphalt surface courses (100), characterized by , that the binder (120) recovered and stabilized from the emulsion has a ring and ball softening point (RuK) according to DIN EN 1427 of more than 60 °C and a penetration at 25 °C according to DIN EN 1426 of less than 25 [0.1 mm]. [2] Bitumen emulsion according to claim 1, characterized by , that the binder (120) is hard bitumen or is obtained from hard bitumen. [3] Bitumen emulsion according to any of the preceding claims, characterized by , that the binder recovered and stabilized from the emulsion (120) has an equi shear modulus temperature at G* = 15 kPa of more than 70 °C, determined according to TP Bitumen-StB Part 2 A. [4] Bitumen emulsion according to any one of the preceding claims, characterized by, that it exhibits an adhesion behavior on aggregates (110), determined according to TP Asphalt-StB Part 11, of more than 70% coverage after 72 hours. [5] Bitumen emulsion according to any one of the preceding claims, characterized by that it is solvent-free. [6] Bitumen emulsion according to any one of the preceding claims, characterized by , that the softening point of ring and ball (RuK) of the recovered and stabilized binder (120) is more than 65 °C, preferably about 67 °C. [7] Bitumen emulsion according to any one of the preceding claims, characterized by , that the penetration at 25 °C of the recovered and stabilized binder (120) is less than 20 [0.1 mm], preferably approximately 18 [0.1 mm].

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