A multi-stage phase change temperature-regulating asphalt pavement structure for alleviating urban heat island effect

Abstract

The present invention discloses a multi-level phase-change temperature-regulating asphalt pavement structure for mitigating the urban heat island effect. The structure comprises, from top to bottom, an upper layer, a lower layer, a base layer, and a subbase layer. The upper layer is formed from a first asphalt mixture admixed with a wide-temperature-range phase-change temperature-regulating system A, which accounts for 7-10% of the volume of the first asphalt mixture and is composed of a combination of multiple different composite organic eutectic phase-change materials. The lower layer is formed from a second asphalt mixture admixed with a wide-temperature-range phase-change temperature-regulating system B, which accounts for 5-10% of the volume of the second asphalt mixture and is composed of a combination of multiple different composite organic eutectic phase-change materials. The present invention introduces composite organic eutectic phase-change materials with different wide-temperature-range phase changes into the upper and lower layers of the asphalt pavement. The combined use of these organic eutectic phase-change materials can significantly absorb heat from within the pavement structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of road engineering, and in particular relates to a multi-stage phase-change temperature-regulating asphalt pavement structure for alleviating the urban heat island effect. Background Art

[0002] The urbanization process causes a serious urban heat island effect (UHI), whereby urban areas are typically warmer than the surrounding rural environment in summer. The main causes of the UHI are the use of specialized building materials, the complex geometry of urban landscapes, reduced vegetation cover, and increased anthropogenic heat emissions. Among these factors, the black asphalt pavement used in urban roads has low reflectivity and a high heat absorption coefficient, absorbing a significant proportion of solar radiation and causing road surface temperatures to reach as high as 65°C, which significantly exacerbates the UHI effect. UHI poses considerable health risks to urban residents, primarily related to heat-related illness and mortality. Furthermore, the viscoelasticity and temperature sensitivity of asphalt pavement make it susceptible to high-temperature damage such as rutting and thermal oxidative aging when exposed to prolonged high temperatures, ultimately affecting the durability and serviceability of the road surface.

[0003] To create a livable urban environment, rational strategies must be adopted to mitigate urban heat islands. Currently, asphalt pavement designs that integrate renewable energy technologies, such as latent heat structures and photovoltaic materials, have emerged as a promising approach to mitigating urban heat islands. These systems reduce surface temperature by converting absorbed radiation into different types of energy. Phase change materials (PCMs) are functional materials with the ability to absorb and release thermal energy during a phase change process, offering a potential solution for regulating temperature fluctuations within pavement structures. When integrated into pavement structural systems, PCMs absorb excess heat energy at the highest daytime temperatures, significantly reducing pavement surface temperatures and providing a viable strategy for counteracting urban heat islands. It is feasible to leverage the latent heat properties of PCMs to impart latent heat capacity to asphalt pavements, thereby mitigating temperature stress and the urban heat island effect. Clearly, numerous studies have demonstrated that leveraging the latent heat properties of PCMs for active pavement temperature control is a viable approach.

[0004] However, due to factors such as the single phase change temperature of commonly used phase change materials, a mismatch with the ambient temperature, low phase change enthalpy, and inappropriate fusion design, their cooling effect on asphalt pavements is very limited, which greatly restricts their widespread application. Therefore, it is urgent to develop pavement phase change temperature control technologies with excellent temperature control performance and significant cooling effects based on the structure of urban asphalt pavements, thereby effectively alleviating the urban heat island effect. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, the present invention provides a multi-stage phase-change temperature-adjustable asphalt pavement structure that mitigates the urban heat island effect. The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0006] The present invention provides a multi-stage phase-change temperature-regulating asphalt pavement structure for alleviating the urban heat island effect, which comprises an upper layer, a lower layer, a base layer and a subbase layer from top to bottom, wherein:

[0007] The upper layer is formed by a first asphalt mixture mixed with a wide temperature range phase change temperature regulating system A, wherein the volume of the wide temperature range phase change temperature regulating system A is 7-10% of the volume of the first asphalt mixture, and the wide temperature range phase change temperature regulating system A is compounded by five different composite organic eutectic phase change materials;

[0008] The lower layer is formed by a second asphalt mixture added with a wide temperature range phase change temperature regulation system B. The volume of the wide temperature range phase change temperature regulation system B is 5 to 10% of the volume of the second asphalt mixture. The wide temperature range phase change temperature regulation system B is compounded by four different composite organic eutectic phase change materials.

[0009] In one embodiment of the present invention, the wide temperature range phase change temperature adjustment system A includes 45 to 55 parts by mass of composite organic eutectic phase change material A-1, 360 to 440 parts by mass of composite organic eutectic phase change material, 270 to 330 parts by mass of composite organic eutectic phase change material A-3, 180 to 220 parts by mass of composite organic eutectic phase change material A-4 and 45 to 55 parts by mass of composite organic eutectic phase change material A-5, wherein,

[0010] The raw materials of the composite organic eutectic phase change material A-1 are 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, 440-540 parts by mass of myristic acid and 90-110 parts by mass of expanded graphite;

[0011] The raw materials of the composite organic eutectic phase change material A-2 are 260-320 parts by mass of stearic acid, 650-790 parts by mass of myristic acid and 90-110 parts by mass of expanded graphite;

[0012] The raw materials of the composite organic eutectic phase change material A-3 are 360 ​​to 440 parts by mass of stearic acid, 540 to 660 parts by mass of palmitic acid and 90 to 110 parts by mass of expanded graphite;

[0013] The raw materials of the composite organic eutectic phase change material A-4 are 25-35 parts by mass of adipic acid, 50-60 parts by mass of sebacic acid, 800-1000 parts by mass of palmitic acid, and 90-110 parts by mass of expanded graphite;

[0014] The raw materials of the composite organic eutectic phase change material A-5 are 20-40 parts by mass of adipic acid, 60-75 parts by mass of sebacic acid, 800-1000 parts by mass of stearic acid and 90-110 parts by mass of expanded graphite.

[0015] In one embodiment of the present invention, the preparation process of the composite organic eutectic phase change material A-1 includes:

[0016] 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, and 440-540 parts by mass of myristic acid are mixed and heated until completely melted, and stirred until completely mixed to form a blended mixture;

[0017] Adding 90 to 110 parts by mass of expanded expanded graphite to the blended mixture, stirring and adsorbing the mixture in a vacuum environment of 70 to 90° C. for 4 to 6 hours, and then placing the mixture in a vacuum drying oven to continue adsorbing the mixture for 40 to 55 hours;

[0018] The adsorbed mixture was taken out, stirred and rinsed with anhydrous ethanol for multiple times, and placed in an oven for drying to obtain the composite organic eutectic phase change material A-1.

[0019] In one embodiment of the present invention, the wide temperature range phase change temperature control system B comprises: 90 to 110 parts by mass of composite organic eutectic phase change material B-1, 90 to 110 parts by mass of composite organic eutectic phase change material B-2, 450 to 550 parts by mass of composite organic eutectic phase change material B-3, and 270 to 330 parts by mass of composite organic eutectic phase change material B-4, wherein:

[0020] The raw materials of the composite organic eutectic phase change material B-1 are 135-165 parts by mass of palmitic acid, 220-270 parts by mass of myristic acid, 540-660 parts by mass of methyl stearate, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide, and 70-90 parts by mass of expanded graphite;

[0021] The raw materials of the composite organic eutectic phase change material B-2 are 130-170 parts by mass of palmitic acid, 770-930 parts by mass of methyl stearate, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide, and 70-90 parts by mass of expanded graphite;

[0022] The raw materials of the composite organic eutectic phase change material B-3 are 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, 450-550 parts by mass of myristic acid, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide, and 70-90 parts by mass of expanded graphite;

[0023] The raw materials of the composite organic eutectic phase change material B-4 are 260-320 parts by mass of stearic acid, 640-780 parts by mass of myristic acid, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide and 70-90 parts by mass of expanded graphite.

[0024] In one embodiment of the present invention, the preparation process of the composite organic eutectic phase change material B-1 includes:

[0025] 135-165 parts by mass of palmitic acid, 220-270 parts by mass of myristic acid, and 540-660 parts by mass of methyl stearate are mixed and heated until completely melted, followed by adding 35-55 parts by mass of multi-walled carbon nanotubes and 55-65 parts by mass of layered graphene oxide, and stirring until completely mixed to form a blended mixture;

[0026] Adding 70 to 90 parts by mass of expanded graphite and 90 to 110 parts by mass of a silane coupling agent to the blended mixture, stirring and adsorbing the mixture under a vacuum environment of 70 to 90° C. for 4 to 6 hours, and then placing the mixture in a vacuum drying oven for further adsorption for 40 to 55 hours;

[0027] The adsorbed mixture was taken out, stirred and rinsed with anhydrous ethanol for multiple times, and placed in an oven for drying to obtain the composite organic eutectic phase change material B-1.

[0028] In one embodiment of the present invention, the thickness of the upper layer is 4 to 6 cm, and the thickness of the lower layer is 6 to 8 cm.

[0029] In one embodiment of the present invention, the asphalt in the first asphalt mixture and the second asphalt mixture are both SBS modified asphalt.

[0030] In one embodiment of the present invention, the first asphalt mixture is AC-13 asphalt mixture; the second asphalt mixture is AC-20 asphalt mixture.

[0031] In one embodiment of the present invention, the base layer consists of two layers of cement-stabilized crushed stone with a thickness of 30 to 34 cm.

[0032] In one embodiment of the present invention, the subbase layer is composed of lime soil and has a thickness of 18 to 22 cm.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention addresses the urban heat island effect and rutting issues caused by high temperatures on urban asphalt pavements during summer, and provides a multi-stage phase-change temperature-regulating asphalt pavement structure to mitigate the urban heat island effect. This pavement structure introduces composite organic eutectic phase change materials with different wide-temperature-range phase transitions into both the upper and lower layers of the asphalt pavement. The combined use of these organic eutectic phase change materials significantly absorbs heat within the structure. Furthermore, the invention fully considers the service life and differentiated heat transfer characteristics of the different structural layers, and tailors the thermal conductivity of the organic eutectic phase change materials used in these layers. This allows for efficient temperature regulation across a wide temperature range within the entire structure, maximizing the potential heat of the phase change, reducing the temperature of the asphalt pavement and prolonging the high-temperature effect, thereby mitigating the urban heat island effect and extending the pavement's durability.

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a module diagram of a multi-stage phase-change temperature-adjustable asphalt pavement structure for alleviating the urban heat island effect, provided by an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of a specific structure of a multi-stage phase-change temperature-adjustable asphalt pavement structure for alleviating the urban heat island effect provided by an embodiment of the present invention;

[0038] Figure 3 This is a cross-sectional view of a multi-stage phase-change temperature-adjustable asphalt pavement structure for alleviating the urban heat island effect, provided by an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of temperature field curves of different implementation cases provided by the embodiments of the present invention. DETAILED DESCRIPTION

[0040] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description of a multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect proposed by the present invention in combination with the accompanying drawings and specific implementation methods.

[0041] The aforementioned and other technical contents, features, and effects of the present invention are clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are provided for reference and illustration purposes only and are not intended to limit the technical solutions of the present invention.

[0042] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0043] Example 1

[0044] The embodiment of the present invention provides a multi-stage phase change temperature regulating asphalt pavement structure to alleviate the urban heat island effect, such as Figures 1 to 3 As shown, the multi-level phase change temperature regulation asphalt pavement structure includes an upper layer, a lower layer, a base layer and a subbase layer from top to bottom, wherein the upper layer is formed by a first asphalt mixture mixed with a wide temperature range phase change temperature regulation system A, the volume of the wide temperature range phase change temperature regulation system A is 7 to 10% of the volume of the first asphalt mixture, and the wide temperature range phase change temperature regulation system A is compounded by 5 different composite organic eutectic phase change materials; the lower layer is formed by a second asphalt mixture mixed with a wide temperature range phase change temperature regulation system B, the volume of the wide temperature range phase change temperature regulation system B is 5 to 10% of the volume of the second asphalt mixture, and the wide temperature range phase change temperature regulation system B is compounded by 4 different composite organic eutectic phase change materials.

[0045] The thickness of the upper layer of this embodiment can be 4 to 6 cm, the thickness of the lower layer can be 6 to 8 cm, the base layer can be composed of two layers of 15 to 17 cm cement-stabilized gravel layers, and the total thickness of the base layer can be 30 to 34 cm; the subbase layer can be composed of 18 to 22 cm lime soil.

[0046] In this embodiment, the first asphalt mixture is AC-13 asphalt mixture, and the second asphalt mixture is AC-20 asphalt mixture. In other embodiments, the first asphalt mixture and the second asphalt mixture can also be selected from other suitable asphalt mixtures according to actual conditions.

[0047] Furthermore, the wide temperature range phase change temperature control system A of this embodiment is composed of a compound of 5 different composite organic eutectic phase change materials, specifically including 45 to 55 parts by mass of composite organic eutectic phase change material A-1, 360 to 440 parts by mass of composite organic eutectic phase change material, 270 to 330 parts by mass of composite organic eutectic phase change material A-3, 180 to 220 parts by mass of composite organic eutectic phase change material A-4 and 45 to 55 parts by mass of composite organic eutectic phase change material A-5.

[0048] Specifically, the raw materials of the composite organic eutectic phase change material A-1 are 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, 440-540 parts by mass of myristic acid and 90-110 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material A-2 are 260-320 parts by mass of stearic acid, 650-790 parts by mass of myristic acid and 90-110 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material A-3 are 360-440 parts by mass of stearic acid, The raw materials of the composite organic eutectic phase change material A-4 are 25-35 parts by mass of adipic acid, 50-60 parts by mass of sebacic acid, 800-1000 parts by mass of palmitic acid and 90-110 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material A-5 are 20-40 parts by mass of adipic acid, 60-75 parts by mass of sebacic acid, 800-1000 parts by mass of stearic acid and 90-110 parts by mass of expanded graphite.

[0049] The preparation process of the composite organic eutectic phase change material A-1 of this embodiment includes:

[0050] 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, and 440-540 parts by mass of myristic acid are mixed and heated until completely melted, and stirred until completely mixed to form a blended mixture; 90-110 parts by mass of expanded expanded graphite are added to the blended mixture, and the mixture is stirred and adsorbed in a vacuum environment of 70-90°C for 4-6 hours, and then placed in a vacuum drying oven for further adsorption for 40-55 hours; the adsorbed mixture is taken out, stirred and rinsed with anhydrous ethanol multiple times, and placed in an oven for drying to obtain a composite organic eutectic phase change material A-1.

[0051] Similar to the preparation process of the composite organic eutectic phase change material A-1, composite organic eutectic phase change materials A-2 to A-5 can be prepared by simply replacing different organic phase change materials in corresponding proportions. For example, the preparation process of composite organic eutectic phase change material A-2 includes:

[0052] 260-320 parts by mass of stearic acid and 650-790 parts by mass of myristic acid are mixed and heated until completely melted, and stirred until completely mixed to form a blended mixture; 90-110 parts by mass of expanded expanded graphite are added to the blended mixture, and the mixture is stirred and adsorbed in a vacuum environment of 70-90°C for 4-6 hours, and then placed in a vacuum drying oven for further adsorption for 40-55 hours; the adsorbed mixture is taken out, stirred and rinsed with anhydrous ethanol multiple times, and placed in an oven for drying to obtain a composite organic eutectic phase change material A-2.

[0053] The preparation process of composite organic eutectic phase change materials A-3 to A-5 is the same as the above preparation process, which will not be repeated here.

[0054] Furthermore, the preparation method of the upper layer of this embodiment includes the following steps:

[0055] An AC-13 asphalt mixture was designed. Using the external admixture method, the prepared wide-temperature-range phase change temperature control system A was directly incorporated into the AC-13 asphalt mixture at a volume fraction of 7-10% of the asphalt mixture. Conventional mixing methods were then used to obtain the material for paving the top layer. It should be noted that the asphalt in the AC-13 asphalt mixture must be SBS-modified asphalt.

[0056] The wide temperature range phase change temperature control system B of this embodiment includes: 90-110 parts by mass of composite organic eutectic phase change material B-1, 90-110 parts by mass of composite organic eutectic phase change material B-2, 450-550 parts by mass of composite organic eutectic phase change material B-3 and 270-330 parts by mass of composite organic eutectic phase change material B-4, wherein the raw materials of composite organic eutectic phase change material B-1 are 135-165 parts by mass of palmitic acid, 220-270 parts by mass of myristic acid, 540-660 parts by mass of methyl stearate, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide and 70-90 parts by mass of expanded graphite; the raw materials of composite organic eutectic phase change material B-2 are 130-170 parts by mass of palmitic acid, 770-93 0 parts by mass of methyl stearate, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide and 70-90 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material B-3 are 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, 450-550 parts by mass of myristic acid, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide and 70-90 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material B-4 are 260-320 parts by mass of stearic acid, 640-780 parts by mass of myristic acid, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide and 70-90 parts by mass of expanded graphite.

[0057] Specifically, the preparation process of the composite organic eutectic phase change material B-1 of this embodiment includes:

[0058] 135-165 parts by mass of palmitic acid, 220-270 parts by mass of myristic acid, and 540-660 parts by mass of methyl stearate are mixed and heated until completely melted, and then 35-55 parts by mass of multi-walled carbon nanotubes and 55-65 parts by mass of layered graphene oxide are added, and stirred until completely mixed to form a blended mixture; 70-90 parts by mass of expanded graphite and 90-110 parts by mass of silane coupling agent are added to the blended mixture, and the mixture is stirred and adsorbed in a vacuum environment at 70-90°C for 4-6 hours, and then placed in a vacuum drying oven for further adsorption for 40-55 hours; the adsorbed mixture is taken out, stirred and rinsed with anhydrous ethanol multiple times, and placed in an oven for drying to obtain a composite organic eutectic phase change material B-1.

[0059] Similar to the preparation process of the composite organic eutectic phase change material B-1, composite organic eutectic phase change materials B-2 to B-4 are prepared by simply replacing different organic phase change materials in corresponding proportions. For example, the preparation process of composite organic eutectic phase change material B-2 includes:

[0060] 130-170 parts by mass of palmitic acid and 770-930 parts by mass of methyl stearate are mixed and heated until completely melted, and then 35-55 parts by mass of multi-walled carbon nanotubes and 55-65 parts by mass of layered graphene oxide are added, and stirred until completely mixed to form a blended mixture; 70-90 parts by mass of expanded graphite and 90-110 parts by mass of silane coupling agent are added to the blended mixture, and the mixture is stirred and adsorbed in a vacuum environment of 70-90°C for 4-6 hours, and then placed in a vacuum drying oven for further adsorption for 40-55 hours; the adsorbed mixture is taken out, stirred and rinsed with anhydrous ethanol multiple times, and placed in an oven for drying to obtain a composite organic eutectic phase change material B-2.

[0061] The preparation process of the composite organic eutectic phase change material B-3 to the composite organic eutectic phase change material B-4 is the same as the above preparation process, which will not be repeated here.

[0062] Furthermore, the preparation method of the following layer comprises the following steps:

[0063] Design an AC-20 asphalt mixture; directly incorporate the wide-temperature-range phase-change temperature-regulating system B into the AC-20 asphalt mixture using the external admixture method at a volume fraction of 5-10% of the asphalt mixture. Mix the mixture using conventional mixing methods to obtain the material for the top layer. It should be noted that the asphalt in the AC-20 asphalt mixture must be SBS-modified asphalt.

[0064] Example 2

[0065] Based on Example 1, this embodiment provides a specific example of a multi-level phase-change temperature-regulating asphalt pavement structure for alleviating the urban heat island effect. The multi-level phase-change temperature-regulating asphalt pavement structure includes, from top to bottom, an upper layer, a lower layer, a base layer, and a subbase layer. The upper layer is formed by a first asphalt mixture admixed with a wide-temperature-range phase-change temperature-regulating system A, the volume of which is 10% of the volume of the first asphalt mixture. The wide-temperature-range phase-change temperature-regulating system A is compounded from five different composite organic eutectic phase change materials. The lower layer is formed by a second asphalt mixture admixed with a wide-temperature-range phase-change temperature-regulating system B, the volume of which is 10% of the volume of the second asphalt mixture. The wide-temperature-range phase-change temperature-regulating system B is compounded from four different composite organic eutectic phase change materials.

[0066] In this example, the upper layer is 5 cm thick, the lower layer is 7 cm thick, the base layer consists of two 16 cm layers of cement-stabilized crushed stone, and the subbase consists of 20 cm of lime soil. The first asphalt mixture in this example is AC-13 asphalt mixture, and the second asphalt mixture is AC-20 asphalt mixture.

[0067] Furthermore, the wide temperature range phase change temperature control system A of this embodiment is composed of a compound of 5 different composite organic eutectic phase change materials, specifically including 50 parts by mass of composite organic eutectic phase change material A-1, 400 parts by mass of composite organic eutectic phase change material, 300 parts by mass of composite organic eutectic phase change material A-3, 200 parts by mass of composite organic eutectic phase change material A-4 and 50 parts by mass of composite organic eutectic phase change material A-5.

[0068] Specifically, the raw materials of the composite organic eutectic phase change material A-1 of this embodiment are 203 parts by mass of stearic acid, 307 parts by mass of palmitic acid, 490 parts by mass of myristic acid and 100 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material A-2 are 286 parts by mass of stearic acid, 724 parts by mass of myristic acid and 100 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material A-3 are 397 parts by mass of stearic acid, 603 parts by mass of palmitic acid and 100 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material A-4 are 27 parts by mass of adipic acid, 55 parts by mass of sebacic acid and 918 parts by mass of palmitic acid and 100 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material A-5 are 33 parts by mass of adipic acid, 66 parts by mass of sebacic acid, 900 parts by mass of stearic acid and 100 parts by mass of expanded graphite.

[0069] The preparation process of the composite organic eutectic phase change material A-1 of this embodiment includes:

[0070] 203 parts of stearic acid, 307 parts of palmitic acid and 490 parts of myristic acid were mixed and heated until completely melted, and stirred at a speed of 300 rad / min for 4 hours. Subsequently, 100 parts of expanded graphite with a particle size of 50 mesh was added to the blended mixture; the above mixture was then stirred and adsorbed in a vacuum environment at 80°C for 5 hours, and then placed in a vacuum drying oven for further adsorption for 48 hours; the adsorbed mixture was then taken out, stirred and rinsed with anhydrous ethanol 5 times; and finally placed in an 80°C oven for drying for 24 hours to obtain a composite organic eutectic phase change material A-1.

[0071] Similar to the preparation process of the composite organic eutectic phase change material A-1, composite organic eutectic phase change materials A-2 to A-5 are prepared by simply replacing different organic phase change materials in corresponding proportions.

[0072] Illustratively, the preparation process of the composite organic eutectic phase change material A-2 includes:

[0073] 286 parts of stearic acid and 724 parts of myristic acid were mixed and heated until completely melted, and stirred at a speed of 300 rad / min for 4 hours. Subsequently, 100 parts of expanded graphite with a particle size of 50 mesh was added to the blended mixture; the above mixture was then stirred and adsorbed under a vacuum environment at 80°C for 5 hours, and then placed in a vacuum drying oven for further adsorption for 48 hours; the adsorbed mixture was then taken out, stirred and rinsed with anhydrous ethanol 5 times; and finally placed in an 80°C oven and dried for 24 hours to obtain a composite organic eutectic phase change material A-2.

[0074] The preparation process of composite organic eutectic phase change materials A-3 to A-5 is the same as the above preparation process, which will not be repeated here.

[0075] Furthermore, the preparation method of the upper layer comprises the following steps:

[0076] An AC-13 asphalt mixture was designed. The wide-temperature-range phase change temperature control system A prepared above was directly added to the AC-13 asphalt mixture at a volume fraction of 10% by volume. The mixture was mixed using conventional mixing methods to obtain the material for the top layer. It should be noted that the asphalt in the AC-13 asphalt mixture must be SBS-modified asphalt.

[0077] The wide temperature range phase change temperature control system B of this embodiment includes: 100 parts by mass of composite organic eutectic phase change material B-1, 100 parts by mass of composite organic eutectic phase change material B-2, 500 parts by mass of composite organic eutectic phase change material B-3 and 300 parts by mass of composite organic eutectic phase change material B-4, wherein the raw materials of composite organic eutectic phase change material B-1 are 153 parts by mass of palmitic acid, 243 parts by mass of myristic acid, 604 parts by mass of methyl stearate, 40 parts by mass of multi-walled carbon nanotubes, 60 parts by mass of layered graphene oxide and 80 parts by mass of expanded graphite; the raw materials of composite organic eutectic phase change material B-2 are 148 parts by mass of palmitic acid, 852 parts by mass of methyl stearate, 40 parts by mass of multi-walled carbon nanotubes, 60 parts by mass of layered graphene oxide and 80 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material B-3 are 203 parts by mass of stearic acid, 307 parts by mass of palmitic acid, 490 parts by mass of myristic acid, 40 parts by mass of multi-walled carbon nanotubes, 60 parts by mass of layered graphene oxide and 80 parts by mass of expanded graphite; the raw materials of the composite organic eutectic phase change material B-4 are 286 parts by mass of stearic acid, 724 parts by mass of myristic acid, 40 parts by mass of multi-walled carbon nanotubes, 60 parts by mass of layered graphene oxide and 80 parts by mass of expanded graphite.

[0078] Furthermore, the preparation process of the composite organic eutectic phase change material B-1 includes:

[0079] 153 parts of palmitic acid, 243 parts of myristic acid and 604 parts of methyl stearate were mixed and heated until completely melted, followed by the addition of 40 parts of multi-walled carbon nanotubes and 60 parts of layered graphene oxide, and the mixture was stirred at 300 rad / min for 4 hours. Subsequently, 80 parts of expanded expanded graphite and 100 parts of silane coupling agent were added to the blended mixture; the above mixture was stirred and adsorbed at 80°C in a vacuum environment for 5 hours, and then placed in a vacuum drying oven for further adsorption for 48 hours; the adsorbed mixture was taken out and rinsed with anhydrous ethanol for 5 times by stirring; and finally, it was placed in an 80°C oven and dried for 24 hours to obtain a composite organic eutectic phase change material B-1.

[0080] According to the above method, composite organic eutectic phase change materials B-2 to B-4 were prepared by simply replacing different organic phase change materials in corresponding proportions.

[0081] Exemplarily, the preparation process of the composite organic eutectic phase change material B-2 is as follows:

[0082] 148 parts of palmitic acid and 852 parts of methyl stearate were mixed and heated until completely melted, followed by the addition of 40 parts of multi-walled carbon nanotubes and 60 parts of layered graphene oxide, and the mixture was stirred and mixed at a speed of 300 rad / min for 4 hours. Subsequently, 80 parts of expanded expanded graphite and 100 parts of silane coupling agent were added to the blended mixture; the above mixture was stirred and adsorbed at 80°C in a vacuum environment for 5 hours, and then placed in a vacuum drying oven for further adsorption for 48 hours; the adsorbed mixture was taken out and rinsed with anhydrous ethanol for 5 times by stirring; and finally, it was placed in an 80°C oven and dried for 24 hours to obtain a composite organic eutectic phase change material B-2.

[0083] The preparation process of the composite organic eutectic phase change material B-3 to the composite organic eutectic phase change material B-4 is the same as the above preparation process, which will not be repeated here.

[0084] Furthermore, the preparation method of the following layer comprises the following steps:

[0085] Design an AC-20 asphalt mixture; directly add the wide-temperature-range phase-change temperature-regulating system B to the AC-20 asphalt mixture at a volume fraction of 7% by volume. Mix the mixture using conventional mixing methods to obtain the material for the top layer. It should be noted that the asphalt in the AC-20 asphalt mixture must be SBS-modified asphalt.

[0086] This invention addresses the urban heat island effect and rutting issues caused by high temperatures in urban asphalt pavements during summer, and provides a multi-stage phase-change temperature-regulating asphalt pavement structure to mitigate the urban heat island effect. This structure introduces composite organic eutectic phase change materials with different wide-temperature-range phase transitions into both the upper and lower layers of the asphalt pavement. This combined use of organic eutectic phase change materials significantly absorbs heat from within the structure. Furthermore, the invention fully considers the service life and differentiated heat transfer characteristics of the different structural layers, and specifically tailors the thermal conductivity of the organic eutectic phase change materials used in these layers. This achieves efficient temperature regulation across a wide temperature range within the entire structure, maximizing the potential heat of the phase change, reducing the asphalt pavement temperature and prolonging the high-temperature effect, thereby mitigating the urban heat island effect and extending the pavement's durability.

[0087] The multi-stage phase change temperature regulating asphalt pavement structure provided by the present invention is further described below with reference to specific examples, but the present invention is not limited to the following examples.

[0088] Implementation Case 1

[0089] In this example, the upper layer uses AC-13 asphalt mixture, and the asphalt mixture is prepared and related test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system A prepared in the above-mentioned Example 2 is added at a rate of 7% by volume of the asphalt mixture; the lower layer uses AC-20 asphalt mixture, and the asphalt mixture is prepared and related test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system B prepared in the above-mentioned Example 2 is added at a rate of 5% by volume of the asphalt mixture.

[0090] Implementation Case 2

[0091] In this example, the upper layer uses AC-13 asphalt mixture, and the asphalt mixture is prepared and related test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system A prepared in the above-mentioned Example 2 is added at a rate of 8% by volume of the asphalt mixture; the lower layer uses AC-20 asphalt mixture, and the asphalt mixture is prepared and related test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system B prepared in the above-mentioned Example 2 is added at a rate of 6% by volume of the asphalt mixture.

[0092] Implementation Case 3

[0093] In this example, the upper layer uses AC-13 asphalt mixture, and the asphalt mixture is prepared and related test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system A prepared in the above-mentioned Example 2 is added at a rate of 9% by volume of the asphalt mixture; the lower layer uses AC-20 asphalt mixture, and the asphalt mixture is prepared and related test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system B prepared in the above-mentioned Example 2 is added at a rate of 7% by volume of the asphalt mixture.

[0094] Implementation Case 4

[0095] In the design, the upper layer uses AC-13 asphalt mixture, and the asphalt mixture is prepared and relevant test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system A prepared in the above embodiment 2 is added at 10% of the volume of the asphalt mixture; the lower layer uses AC-20 asphalt mixture, and the asphalt mixture is prepared and relevant test specimens are formed in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E-20-2011). After the addition of mineral powder, the wide temperature range phase change temperature control system B prepared in the above embodiment 2 is added at 8% of the volume of the asphalt mixture.

[0096] Taking the sample without phase change material as the control group, the performance of different implementation cases is shown in Table 1. It can be seen from Table 1 that the rutting depths in the four different implementation cases are 3.64mm, 3.23mm, 2.54mm and 1.96mm respectively. These rutting depths are significantly lower than the 14.98mm of AC-13 asphalt mixture (control group), with the maximum reduction of about 7.6 times. The final rutting depth of the asphalt mixture is usually related to its anti-rutting ability. The lower the rutting depth, the better its resistance to permanent deformation. Obviously, the introduction of a wide temperature range phase change temperature control system into the asphalt mixture makes it show more outstanding resistance to rutting and water damage. Furthermore, the temperature field of the pavement structure under different implementation cases was simulated by ABAQUS finite element simulation software. The temperature field simulation results are shown as follows. Figure 4 As shown in the figure, the pavement structure represents the control group without adding phase change materials. Figure 4 It can be seen that as the depth of the pavement structure increases, the temperature conditions under the four implementation cases show a decreasing trend, which means that the heat transfer in the pavement structure has a downward decreasing characteristic. It is worth noting that at the same depth, the temperature curve of the multi-stage phase change temperature regulating asphalt pavement structure is always lower than that of the traditional type of asphalt pavement structure between about 8:00 and 16:00. At the same time, as the depth of the pavement structure increases, the temperature difference is gradually reduced, and the temperature change also shows a lag phenomenon. Specifically, by Figure 4 From the temperature difference curve in FIG, it can be seen that the negative temperature difference of the multi-stage phase change temperature-regulating asphalt pavement structure lasts for about 7 hours, and the maximum temperature difference is about 7°C (the bottom of the upper layer of implementation case 4).

[0097] Table 1 Hamburger rutting test results of different samples

[0098] Sample Rutting depth (mm) AC-13 asphalt mixture (control group) 14.98 Implementation Case 1: Top layer asphalt mixture 3.64 Implementation Case 2: Top layer asphalt mixture 3.23 Implementation Case 3: Top layer asphalt mixture 2.54 Implementation Case 4: Top layer asphalt mixture 1.96

[0099] Table 2 shows the daily maximum temperatures at the road surface, the bottom of the upper layer, and the bottom of the lower layer. As can be seen from Table 2, the daily maximum temperatures for the four different multi-stage phase change temperature-controlled asphalt pavement implementations were significantly lower than those at the corresponding points on the conventional asphalt pavement. On the road surface, the daily maximum temperatures for the four different implementations were 61.82°C, 60.78°C, 60.38°C, and 60.21°C, respectively, which were 2.98°C, 4.02°C, 4.42°C, and 4.59°C lower than the control group, respectively. Similarly, the maximum temperature differences at the bottom of the upper layer and the bottom of the lower layer were 6.96°C and 4.94°C, respectively.

[0100] Table 2. Simulation results of daily maximum temperature

[0101]

[0102] The wide-temperature-range phase-change thermoregulation system A provided by this invention has a phase-change endothermic process covering a temperature range of 40°C to 70°C, involves a multi-stage phase-change process, and fully matches the summer temperature conditions of the upper layer of urban asphalt pavements. Its low thermal conductivity ensures a continuous and effective phase-change process. Meanwhile, the wide-temperature-range phase-change thermoregulation system B has a phase-change endothermic process covering a temperature range of 30°C to 50°C, fully matching the summer temperature conditions of the lower layer of urban asphalt pavements. It also has high thermal conductivity, allowing it to rapidly transfer heat from the lower layer to the roadbed during the multi-stage phase-change endothermic reaction.

[0103] The combined use of wide-temperature, multi-stage phase transitions in the upper and lower layers effectively absorbs the majority of heat within the pavement structure and rapidly transfers it to the subgrade. Numerical simulations have demonstrated that the pavement structure of this invention can consistently reduce the overall pavement temperature for 10 hours, with a maximum temperature difference of 8°C. This reduces the daily maximum temperature in each structural layer of the asphalt pavement by up to 7°C, delaying the onset of the daily maximum temperature by 2 hours, and simultaneously improving pavement rutting performance by 300%. This mitigates the urban heat island effect and improves pavement durability.

[0104] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A multi-stage phase change temperature-adjustable asphalt pavement structure for alleviating the urban heat island effect, characterized in that: From top to bottom, it includes the upper layer, lower layer, base layer and subbase layer, among which, The upper layer is formed by a first asphalt mixture mixed with a wide temperature range phase change temperature adjustment system A, the volume of the wide temperature range phase change temperature adjustment system A is 7-10% of the volume of the first asphalt mixture, and the wide temperature range phase change temperature adjustment system A is compounded by a plurality of different composite organic eutectic phase change materials; The lower layer is formed by a second asphalt mixture added with a wide temperature range phase change temperature regulating system B, the volume of the wide temperature range phase change temperature regulating system B is 5-10% of the volume of the second asphalt mixture, and the wide temperature range phase change temperature regulating system B is compounded by a plurality of different composite organic eutectic phase change materials; The wide temperature range phase change temperature adjustment system A comprises 45-55 parts by mass of composite organic eutectic phase change material A-1, 360-440 parts by mass of composite organic eutectic phase change material, 270-330 parts by mass of composite organic eutectic phase change material A-3, 180-220 parts by mass of composite organic eutectic phase change material A-4 and 45-55 parts by mass of composite organic eutectic phase change material A-5, wherein: The raw materials of the composite organic eutectic phase change material A-1 are 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, 440-540 parts by mass of myristic acid and 90-110 parts by mass of expanded graphite; The raw materials of the composite organic eutectic phase change material A-2 are 260-320 parts by mass of stearic acid, 650-790 parts by mass of myristic acid and 90-110 parts by mass of expanded graphite; The raw materials of the composite organic eutectic phase change material A-3 are 360-440 parts by mass of stearic acid, 540-660 parts by mass of palmitic acid and 90-110 parts by mass of expanded graphite; The raw materials of the composite organic eutectic phase change material A-4 are 25-35 parts by mass of adipic acid, 50-60 parts by mass of sebacic acid, 800-1000 parts by mass of palmitic acid, and 90-110 parts by mass of expanded graphite; The raw materials of the composite organic eutectic phase change material A-5 are 20-40 parts by mass of adipic acid, 60-75 parts by mass of sebacic acid, 800-1000 parts by mass of stearic acid, and 90-110 parts by mass of expanded graphite.

2. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to claim 1 is characterized in that: The preparation process of the composite organic eutectic phase change material A-1 includes: 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, and 440-540 parts by mass of myristic acid are mixed and heated until completely melted, and stirred until completely mixed to form a blended mixture; Adding 90-110 parts by mass of expanded expanded graphite to the blended mixture, stirring and adsorbing the mixture in a vacuum environment of 70-90° C. for 4-6 hours, and then placing the mixture in a vacuum drying oven to continue adsorption for 40-55 hours; The adsorbed mixture was taken out, stirred and rinsed with anhydrous ethanol for multiple times, and placed in an oven for drying to obtain the composite organic eutectic phase change material A-1.

3. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to claim 1 is characterized in that: The wide temperature range phase change temperature control system B includes 90-110 parts by mass of composite organic eutectic phase change material B-1, 90-110 parts by mass of composite organic eutectic phase change material B-2, 450-550 parts by mass of composite organic eutectic phase change material B-3 and 270-330 parts by mass of composite organic eutectic phase change material B-4, wherein: The raw materials of the composite organic eutectic phase change material B-1 are 135-165 parts by mass of palmitic acid, 220-270 parts by mass of myristic acid, 540-660 parts by mass of methyl stearate, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide, and 70-90 parts by mass of expanded graphite; The raw materials of the composite organic eutectic phase change material B-2 are 130-170 parts by mass of palmitic acid, 770-930 parts by mass of methyl stearate, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide, and 70-90 parts by mass of expanded graphite; The raw materials of the composite organic eutectic phase change material B-3 are 180-220 parts by mass of stearic acid, 270-330 parts by mass of palmitic acid, 450-550 parts by mass of myristic acid, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide, and 70-90 parts by mass of expanded graphite; The raw materials of the composite organic eutectic phase change material B-4 are 260-320 parts by mass of stearic acid, 640-780 parts by mass of myristic acid, 35-55 parts by mass of multi-walled carbon nanotubes, 55-65 parts by mass of layered graphene oxide, and 70-90 parts by mass of expanded graphite.

4. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to claim 3 is characterized in that: The preparation process of the composite organic eutectic phase change material B-1 includes: 135-165 parts by mass of palmitic acid, 220-270 parts by mass of myristic acid, and 540-660 parts by mass of methyl stearate are mixed and heated until completely melted, followed by adding 35-55 parts by mass of multi-walled carbon nanotubes and 55-65 parts by mass of layered graphene oxide, and stirring until completely mixed to form a blended mixture; Add 70-90 parts by mass of expanded graphite and 90-110 parts by mass of a silane coupling agent to the blended mixture, stir and adsorb for 4-6 hours in a vacuum environment at 70-90° C., and then place in a vacuum drying oven to continue adsorption for 40-55 hours; The adsorbed mixture was taken out, stirred and rinsed with anhydrous ethanol for multiple times, and placed in an oven for drying to obtain the composite organic eutectic phase change material B-1.

5. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to claim 1 is characterized in that: The thickness of the upper layer is 4-6 cm, and the thickness of the lower layer is 6-8 cm.

6. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to claim 1 is characterized in that: The asphalt in the first asphalt mixture and the second asphalt mixture are both SBS modified asphalt.

7. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to claim 1 is characterized in that: The first asphalt mixture is AC-13 asphalt mixture; the second asphalt mixture is AC-20 asphalt mixture.

8. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to any one of claims 1 to 7, characterized in that: The base layer consists of two layers of cement-stabilized crushed stone with a thickness of 30 to 34 cm.

9. The multi-stage phase change temperature regulating asphalt pavement structure for alleviating the urban heat island effect according to any one of claims 1 to 7, characterized in that: The base layer is composed of lime soil and has a thickness of 18 to 22 cm.

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