A precast component made of recycled asphalt concrete and its preparation method

Abstract

This invention belongs to the field of recycled concrete materials, specifically relating to a recycled asphalt concrete precast component and its preparation method. The recycled asphalt concrete precast component of this invention comprises the following components by weight: 100 parts waste asphalt mixture, 2-4 parts fresh asphalt, 8-12 parts mineral admixtures, and 5-10 parts asphalt modifier; wherein the asphalt modifier contains SBS modified asphalt, SBS, and polymer fibers in a weight ratio of 3-5:1.5-3.5:0.5-1.5. This invention discovers that by optimizing the formulation, the compatibility between waste asphalt mixture and fresh asphalt can be significantly improved, while the adverse effects of internal cracks in recycled aggregates on material properties can be largely avoided, thus giving the recycled asphalt concrete precast component good mechanical properties and water resistance. Furthermore, the preparation method of this invention is simple and efficient, which is conducive to its widespread application in actual production.

Description

Technical Field

[0001] This invention belongs to the field of recycled concrete materials, specifically relating to a recycled asphalt concrete precast component and its preparation method. Background Technology

[0002] Asphalt concrete pavement is a major pavement type for high-grade highways, with a design service life of generally 10-15 years. However, due to the rapid increase in traffic volume, most asphalt pavements experience severe overloading and over-consumption during operation. Furthermore, the combined effects of adverse environmental factors such as rain and snow significantly reduce their actual service life. The repair and maintenance of these increasingly waste asphalt pavements generate a massive amount of waste asphalt mixture (RAP). How to handle such a large amount of waste is one of the key technical challenges that urgently needs to be addressed in the current road construction field.

[0003] Currently, there are few existing technologies for the extensive application of RAP in precast components made from recycled asphalt mixtures, and even fewer for its application to fine aggregates with high asphalt content. As RAP undergoes use and aging over a period of time, it may deteriorate, separate, or become damaged. During recycling, special attention must be paid to the impact of aged asphalt binder and damaged aggregates on material quality and performance, and suitable methods for repair or improvement must be sought.

[0004] CN113998923A describes a precast asphalt concrete component based on solid waste materials and its preparation method. This method involves mixing waste road recycled materials with waste plastic powder in a certain proportion, followed by microwave heating to prepare the precast asphalt concrete component. This achieves 100% utilization of road milling material and fully utilizes waste fine materials with high asphalt content, saving on the amount of new asphalt. Surface treatment of the precast component with an emulsified asphalt slurry seal mixture can increase its water resistance and erosion resistance, while also improving its mechanical properties. However, this approach has several drawbacks: 1) Due to differences in material type, additives, and other impurities among waste plastics, and the varying degrees of deterioration and aging, it is difficult to guarantee the expected performance of the resulting precast asphalt concrete component when using consistent recycling methods to solidify the road recycled materials; 2) This approach also requires the preparation of an emulsified asphalt slurry seal to ensure the water resistance and mechanical properties of the precast component. The layered preparation method is not conducive to improving preparation efficiency and further increases the preparation difficulty.

[0005] Therefore, there is still room for improvement in the technology of using RAP to prepare precast asphalt concrete components. Summary of the Invention

[0006] This invention provides a precast recycled asphalt concrete component with good mechanical and water resistance properties, and a simple and efficient preparation method, as well as its preparation method.

[0007] Specifically, the present invention first provides a precast recycled asphalt concrete component, which comprises the following components by weight: 100 parts of waste asphalt mixture, 2-4 parts of fresh asphalt, 8-12 parts of mineral admixture, and 5-10 parts of asphalt modifier; wherein the asphalt modifier contains SBS modified asphalt, SBS (styrene-butadiene rubber blend), and polymer fiber in a weight ratio of 3-5:1.5-3.5:0.5-1.5.

[0008] As a preferred embodiment, the polymer fiber is selected from one or more of polypropylene fiber, polyester fiber, polyethylene fiber, fiber glass fiber, and polyamide fiber.

[0009] As a more preferred embodiment, the polymer fiber comprises polypropylene fiber and polyester fiber in a weight ratio of 1 to 4: 1 to 2.

[0010] As a preferred embodiment, the mineral admixture is selected from one or more of stone powder, silica fume, slag powder and fly ash.

[0011] As a more preferred embodiment, the mineral admixture comprises stone powder, silica fume, and component A in a weight ratio of 1-3:3-5:1-4, wherein component A is selected from one or two of slag powder and fly ash.

[0012] As a preferred embodiment, the mineral admixture has a particle size of less than 0.6 mm, with more than 90% of the components having a particle size of less than 0.15 mm and more than 75% of the components having a particle size of less than 0.075 mm.

[0013] As a preferred embodiment, the fresh asphalt is emulsified asphalt.

[0014] As a preferred embodiment, some or all of the aged asphalt binder in the waste asphalt mixture has been removed or modified.

[0015] As a preferred embodiment, the waste asphalt mixture comprises 60-75 parts of a component with a diameter of 5-25 mm and 25-40 parts of a component with a diameter of 0.075-4.75 mm.

[0016] As a preferred embodiment, the waste asphalt mixture contains 10-20 wt% asphalt.

[0017] This invention further provides a method for preparing precast recycled asphalt concrete components, comprising:

[0018] After mixing the components of the recycled asphalt concrete precast component, the mixture is poured into a mold. Once formed, the recycled asphalt concrete precast component is removed from the mold.

[0019] As a preferred option, the waste asphalt mixture is pretreated using one or more of the following methods: thermal recycling, chemical methods, and mechanical methods, so that some or all of the aged asphalt binder is removed or modified.

[0020] As a preferred embodiment, the waste asphalt mixture is crushed and screened to obtain a waste asphalt mixture containing 60-75 parts of a component with a diameter of 5-25 mm and 25-40 parts of a component with a diameter of 0.075-4.75 mm.

[0021] This invention discovers that by optimizing the formulation of recycled asphalt concrete precast components, the compatibility between waste asphalt mixtures and fresh asphalt can be significantly improved. Simultaneously, the adverse effects of internal cracks in recycled aggregates on material properties can be largely avoided, resulting in recycled asphalt concrete precast components possessing excellent mechanical and water resistance properties. Furthermore, the preparation method of this invention is simple and efficient, facilitating its widespread application in actual production. Detailed Implementation

[0022] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the invention. Those skilled in the art can make various modifications and variations to the invention without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment can be used in another embodiment to produce further embodiments.

[0023] Unless otherwise stated, all terms used to disclose this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Further guidance is provided below for a better understanding of the teachings of this invention. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0024] The terms "and / or," "or / and," and "and / or" as used herein include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND," and also undoubtedly includes technical solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0025] The terms “containing,” “comprising,” and “including” as used in this invention are synonyms and are inclusive or open-ended, not excluding additional, uncited members, elements, or method steps.

[0026] In this invention, the numerical range represented by endpoints includes all numerical values ​​and fractions contained within that range, as well as the endpoints mentioned.

[0027] This invention relates to concentration values, which include fluctuations within a certain range. For example, fluctuations are allowed within a corresponding precision range. For instance, 2% can fluctuate within ±0.1%. For larger values ​​or values ​​that do not require overly precise control, even greater fluctuations are permitted.

[0028] In this invention, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity of 2 or more.

[0029] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0030] In this invention, terms such as "preferred," "better," "more suitable," and "ideal" merely describe implementation methods or embodiments with better effects and should be understood not to limit the scope of protection of this invention. In this invention, terms such as "optionally," "optionally," and "optional" mean that something is optional, that is, selected from either "with" or "without" a parallel solution. If multiple "optional" statements appear in a technical solution, unless otherwise specified and without contradiction or mutual constraint, each "optional" statement is independent.

[0031] Recycled asphalt concrete precast components

[0032] The present invention first provides a precast recycled asphalt concrete component, which comprises the following components by weight: 100 parts of waste asphalt mixture, 2-4 parts of fresh asphalt, 8-12 parts of mineral admixture, and 5-10 parts of asphalt modifier; wherein the asphalt modifier contains SBS modified asphalt, SBS (styrene-butadiene rubber blend), and polymer fiber in a weight ratio of 3-5:1.5-3.5:0.5-1.5.

[0033] The present invention unexpectedly discovered that the above formula can significantly improve the compatibility between waste asphalt mixture and fresh asphalt, while also better filling the cracks in RAP aggregate and increasing the adhesion between recycled aggregate and asphalt, thereby significantly improving the mechanical properties and water resistance of recycled asphalt concrete precast components.

[0034] In some embodiments, the polymer fiber is selected from one or more of polypropylene fiber (PP fiber), polyester fiber (PET fiber), polyethylene fiber (PE fiber), fiber glass fiber, and polyamide fiber (PA fiber).

[0035] In some embodiments, the polymer fiber is selected from one or both of polypropylene fiber (PP fiber) and polyester fiber (PET fiber).

[0036] In some embodiments, the polymer fibers comprise polypropylene fibers and polyester fibers in a weight ratio of 1–4:1–2. This compounding method will help to further improve the crack resistance and durability of recycled asphalt concrete precast components.

[0037] In some embodiments, the mineral admixture is selected from one or more of stone powder, silica fume, slag powder, and fly ash.

[0038] In some embodiments, the mineral admixture comprises stone powder, silica fume, and component A in a weight ratio of 1–3:3–5:1–4, wherein component A is selected from one or both of slag powder and fly ash. This compounding method will help to further improve the compressive strength and durability of recycled asphalt concrete precast components.

[0039] In some embodiments, the mineral admixture has a particle size of less than 0.6 mm, with more than 90% of the components having a particle size of less than 0.15 mm and more than 75% of the components having a particle size of less than 0.075 mm. This will further improve the blending effect between the mineral admixture and the aggregate, thereby further improving the material properties of the recycled asphalt concrete precast components.

[0040] In some embodiments, the fresh asphalt is emulsified asphalt.

[0041] In some embodiments, some or all of the aged asphalt binder in the waste asphalt mixture has been removed or modified. This further improves the compatibility of the waste asphalt mixture with fresh asphalt and helps to ensure the material properties of the recycled asphalt concrete precast components.

[0042] In some embodiments, the waste asphalt mixture comprises 60-75 parts of a 5-25 mm component and 25-40 parts of a 0.075-4.75 mm component.

[0043] In some embodiments, the waste asphalt mixture contains 10-20 wt% asphalt. Such a waste asphalt mixture will help to further ensure the material properties of recycled asphalt concrete precast components. At the same time, this invention, by improving the compatibility of waste asphalt mixtures and fresh asphalt, also lays the foundation for the recycling of high-asphalt-content RAP.

[0044] In specific implementation, those skilled in the art can combine the above-mentioned implementation schemes with common sense to obtain preferred embodiments of the recycled asphalt concrete precast components of the present invention.

[0045] Preparation method of recycled asphalt concrete precast components

[0046] The present invention further provides a method for preparing the aforementioned recycled asphalt concrete precast component, comprising:

[0047] After mixing the components of the recycled asphalt concrete precast component, the mixture is poured into a mold. Once formed, the recycled asphalt concrete precast component is removed from the mold.

[0048] In practice, to achieve better mixing results, those skilled in the art can adjust the mixing temperature (e.g., 150-160°C), mixing speed, and mixing time to ensure sufficient fluidity and uniformity of components such as asphalt, thereby ensuring the quality of concrete. This invention does not impose any particular limitations on the above parameters.

[0049] In some embodiments, the waste asphalt mixture is pretreated using one or more of the following methods: thermal recycling, chemical methods, and mechanical methods, so as to remove or modify some or all of the aged asphalt binder.

[0050] In this invention, "thermal recycling" refers to the process of softening and separating aged asphalt binders from waste asphalt mixtures by heating them. This can be carried out in specialized thermal recycling equipment, where the aged asphalt binders are separated through high-temperature heating. The processing temperature is generally between 120 and 180°C, a temperature range that allows the aged asphalt binders to soften and separate without causing excessive volatilization loss or excessive thermal cracking.

[0051] The "chemical method" in this invention refers to using solvents or chemical solutions to separate aged asphalt binders from waste asphalt mixtures. In practice, waste asphalt mixtures can be contacted with chemical solvents to separate the aged asphalt binders and separate them from the aggregates.

[0052] In this invention, "mechanical method" refers to the use of mechanical force to peel, crush, or screen asphalt mixtures, which can remove some or all of the aged asphalt binder.

[0053] In some specific implementations, those skilled in the art can combine two or more of the above-mentioned thermal regeneration, chemical methods, and mechanical methods to achieve better removal results.

[0054] In some embodiments, the waste asphalt mixture is crushed and screened to obtain a waste asphalt mixture containing 60-75 parts of a component with a diameter of 5-25 mm and 25-40 parts of a component with a diameter of 0.075-4.75 mm.

[0055] In practical implementation, those skilled in the art can also vibrate the concrete after pouring it into the mold to remove air bubbles and improve the density of the material; they can also cure the cast precast components, including measures such as covering and protecting, and moist curing, to ensure the development of the concrete's strength and stability. The present invention does not specifically limit or describe the above-mentioned detailed operations.

[0056] In specific implementation, those skilled in the art can combine the above-mentioned implementation schemes with common sense to obtain preferred embodiments of the method for preparing recycled asphalt concrete precast components of the present invention.

[0057] Example

[0058] The embodiments of the present invention will now be described in detail with reference to examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0059] For ease of comparison, the waste asphalt mixtures in the following examples and comparative examples belong to the same batch of materials and underwent uniform pretreatment using the following method: the waste asphalt mixture was crushed and screened to obtain a waste asphalt mixture containing 75 parts by weight of a component with a diameter of 5–25 mm and 25 parts by weight of a component with a diameter of 0.075–4.75 mm; the waste asphalt mixture was pretreated at 180°C for 1 hour using a hot recycling method. After the above treatment, the asphalt content in the waste asphalt mixture was measured to be 15 wt%.

[0060] For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this invention, or follow experimental manuals or conventional conditions in the field, or other experimental methods known in the field, or follow the conditions recommended by the manufacturer.

[0061] In the specific embodiments described below, the measurement parameters involving raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision.

[0062] Example 1

[0063] This embodiment first provides a precast component made of recycled asphalt concrete, which comprises the following components in parts by weight:

[0064] 100 parts of waste asphalt mixture, 3 parts of emulsified asphalt, 10 parts of mineral admixture, and 8 parts of asphalt modifier.

[0065] The asphalt modifier contains SBS modified asphalt, SBS, and polymer fibers in a weight ratio of 4:2.5:1.5.

[0066] The polymer fiber comprises polypropylene fiber and polyester fiber in a weight ratio of 2:1.

[0067] The mineral admixture comprises stone powder, silica fume, and fly ash in a weight ratio of 2:4:4.

[0068] The mineral admixture has a particle size of less than 0.6 mm, with more than 90% of the components having a particle size of less than 0.15 mm and more than 75% of the components having a particle size of less than 0.075 mm.

[0069] This embodiment further provides a method for preparing the above-mentioned recycled asphalt concrete precast component, wherein the components of the recycled asphalt concrete precast component are mixed at 160°C, then poured into a mold, and after molding, the recycled asphalt concrete precast component is taken out from the mold.

[0070] Example 2

[0071] This embodiment provides a precast component made of recycled asphalt concrete, which comprises the following components in parts by weight:

[0072] 100 parts of waste asphalt mixture, 2 parts of emulsified asphalt, 12 parts of mineral admixture, and 10 parts of asphalt modifier.

[0073] The asphalt modifier contains SBS modified asphalt, SBS, and polymer fibers in a weight ratio of 5:3.5:1.5.

[0074] The polymer fiber comprises polypropylene fiber and polyester fiber in a weight ratio of 4:1.

[0075] The mineral admixture comprises stone powder, silica fume, and fly ash in a weight ratio of 3:5:4.

[0076] The mineral admixture has a particle size of less than 0.6 mm, with more than 90% of the components having a particle size of less than 0.15 mm and more than 75% of the components having a particle size of less than 0.075 mm.

[0077] The preparation method is the same as in Example 1.

[0078] Example 3

[0079] This embodiment provides a precast component made of recycled asphalt concrete, which comprises the following components in parts by weight:

[0080] 100 parts waste asphalt mixture, 4 parts emulsified asphalt, 8 parts mineral admixture, and 5 parts asphalt modifier.

[0081] The asphalt modifier contains SBS modified asphalt, SBS, and polymer fibers in a weight ratio of 3:1.5:0.5.

[0082] The polymer fiber comprises polypropylene fiber and polyester fiber in a weight ratio of 1:1.

[0083] The mineral admixture comprises stone powder, silica fume, and slag powder in a weight ratio of 1:3:4.

[0084] The mineral admixture has a particle size of less than 0.6 mm, with more than 90% of the components having a particle size of less than 0.15 mm and more than 75% of the components having a particle size of less than 0.075 mm.

[0085] The preparation method is the same as in Example 1.

[0086] Example 4

[0087] This embodiment provides a precast component made of recycled asphalt concrete, which comprises the following components in parts by weight:

[0088] 100 parts of waste asphalt mixture, 3 parts of emulsified asphalt, 10 parts of mineral admixture, and 8 parts of asphalt modifier.

[0089] The asphalt modifier contains SBS modified asphalt, SBS, and polymer fibers in a weight ratio of 4:2.5:1.5.

[0090] The polymer fiber is polypropylene fiber.

[0091] The mineral admixture comprises stone powder, silica fume, and fly ash in a weight ratio of 2:4:4.

[0092] The mineral admixture has a particle size of less than 0.6 mm, with more than 90% of the components having a particle size of less than 0.15 mm and more than 75% of the components having a particle size of less than 0.075 mm.

[0093] The preparation method is the same as in Example 1.

[0094] Example 5

[0095] This embodiment provides a precast component made of recycled asphalt concrete, which comprises the following components in parts by weight:

[0096] 100 parts of waste asphalt mixture, 3 parts of emulsified asphalt, 10 parts of mineral admixture, and 8 parts of asphalt modifier.

[0097] The asphalt modifier contains SBS modified asphalt, SBS, and polymer fibers in a weight ratio of 4:2.5:1.5.

[0098] The polymer fiber comprises polypropylene fiber and polyester fiber in a weight ratio of 2:1.

[0099] The mineral admixture is fly ash.

[0100] The mineral admixture has a particle size of less than 0.6 mm, with more than 90% of the components having a particle size of less than 0.15 mm and more than 75% of the components having a particle size of less than 0.075 mm.

[0101] The preparation method is the same as in Example 1.

[0102] Comparative Example 1

[0103] This comparative example provides a precast component made of recycled asphalt concrete, which differs from Example 1 only in that SBS modified asphalt is replaced with an equal amount of natural rubber.

[0104] The preparation method is the same as in Example 1.

[0105] Comparative Example 2

[0106] This comparative example provides a precast component made of recycled asphalt concrete, which differs from Example 1 only in that SBS (styrene-butadiene rubber blend) is replaced with an equal amount of SBR (styrene-butadiene rubber).

[0107] The preparation method is the same as in Example 1.

[0108] Test case

[0109] Referring to industry standard documents, the road performance of the recycled asphalt concrete precast components in each embodiment and comparative example was tested, and the test results are shown in Table 1 below:

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from the above, the recycled asphalt concrete precast components of the present invention are significantly superior to the comparative examples in terms of mechanical properties and water stability, possessing excellent comprehensive performance. Furthermore, the preparation method of the present invention is simple and efficient, which is conducive to its widespread application in actual production.

[0114] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A recycled asphalt concrete precast element, characterized in that, It comprises the following components by weight: 100 parts of waste asphalt mixture, 2-4 parts of fresh asphalt, 8-12 parts of mineral admixture, and 5-10 parts of asphalt modifier; The asphalt modifier contains SBS modified asphalt, SBS and polymer fiber in a weight ratio of 3-5:1.5-3.5:0.5-1.5; The polymer fiber contains polypropylene fiber and polyester fiber in a weight ratio of 1-4:1-2; The mineral admixture contains stone powder, silica fume and component A in a weight ratio of 1-3:3-5:1-4, and the component A is selected from one or both of slag powder and fly ash; The particle size of the mineral admixture is less than 0.6 mm, and more than 90% of the components have a particle size less than 0.15 mm, and more than 75% of the components have a particle size less than 0.075 mm; The waste asphalt mixture contains 10-20 wt% of asphalt.

2. The recycled asphalt concrete preform of claim 1, wherein, The fresh asphalt is emulsified asphalt.

3. The recycled asphalt concrete preform of claim 1, wherein, Part or all of the aged asphalt binder in the waste asphalt mixture has been removed or modified.

4. The recycled asphalt concrete preform of claim 1, wherein, The waste asphalt mixture contains 60-75 parts of components with a size of 5-25 mm and 25-40 parts of components with a size of 0.075-4.75 mm.

5. The method for preparing the recycled asphalt concrete precast member according to any one of claims 1-4, comprising: After mixing the components of the recycled asphalt concrete precast member, pouring them into a mold, and taking out the recycled asphalt concrete precast member from the mold after molding.

6. The method of claim 5, wherein the reclaimed asphalt concrete preform is prepared by the method comprising: Using one or more of thermal recycling, chemical methods, and mechanical methods to pretreat the waste asphalt mixture, so that part or all of the aged asphalt binder is removed or modified.

7. The method of producing a recycled asphalt concrete preform according to claim 5 or 6, wherein, After crushing and screening the waste asphalt mixture, a waste asphalt mixture containing 60-75 parts of components with a size of 5-25 mm and 25-40 parts of components with a size of 0.075-4.75 mm is obtained.

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