An anti-skid surface layer asphalt mixture of calcined bauxite / ceramic aggregate, and a preparation method and application thereof

Abstract

The application provides an anti-sliding surface layer asphalt mixture of calcined bauxite / ceramic aggregate composite aggregate and a preparation method and application thereof. The asphalt mixture comprises, in terms of volume percentage, 10-40% of ceramic aggregate with a particle size of 4.75-9.5 mm, 10-40% of calcined bauxite with a particle size of 4.75-9.5 mm, 10-40% of stone with a particle size of 4.75-9.5 mm, 30-50% of stone with a particle size of 0.075-4.75 mm, 3-8% of mineral powder with a particle size of 0-0.075 mm, and 5.5-7.5% of modified asphalt, which accounts for 5.5-7.5% of the total mass of the above-mentioned raw materials. The calcined bauxite / ceramic aggregate material is compounded, the asphalt pavement can still maintain good surface texture and structure under the long-term action of vehicle tires, the regenerated texture is formed, the long-term anti-sliding ability and anti-wear ability of the surface layer of the pavement are improved, the mechanical properties of the asphalt mixture are improved at the same time, and the driving safety of the expressway is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of road materials, and particularly relates to a calcined bauxite / ceramic aggregate composite anti-skid surface layer asphalt mixture and a preparation method and application thereof. BACKGROUND

[0002] With the development of modern transportation, road traffic safety has become a focus problem in the transportation industry in China. The anti-skid performance is an important factor affecting road traffic safety. According to the survey, the road sections with lower accident rates on the expressway have relatively larger structure depths and friction coefficients (good anti-skid performance), and the road sections with higher accident rates have poor anti-skid performance. Therefore, the improvement of road operating conditions and the reduction of traffic accident rates depend largely on the anti-skid performance of the road surface.

[0003] On the other hand, the Highway Asphalt Pavement Design Specification of China requires that the structure depth and transverse friction coefficient of the asphalt surface layer be detected when the newly built road surface is accepted, but these indexes only reflect the anti-skid performance of the road surface in the initial service period and cannot completely indicate the anti-skid performance of the asphalt road surface. For example, although part of the asphalt road surface can meet the specification requirements when it is accepted, the anti-skid indexes of the road surface quickly decay below the specification requirements after a period of vehicle load action. At present, many expressways are facing the phenomenon of obvious decay of anti-skid indexes.

[0004] Therefore, it is necessary to provide an improved technical solution for the above-mentioned deficiencies of the prior art. SUMMARY

[0005] In view of the poor anti-skid durability of the asphalt road surface in the prior art, the present application aims to provide a calcined bauxite / ceramic aggregate composite anti-skid surface layer asphalt mixture and a preparation method and application thereof.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solution:

[0007] The present application provides a calcined bauxite / ceramic aggregate composite anti-skid surface layer asphalt mixture, which comprises: aggregate with a particle size of 0-0.075 mm, aggregate with a particle size of 0.075-4.75 mm, aggregate with a particle size of 4.75-9.5 mm, and modified asphalt.

[0008] The aggregate with a particle size of 0-0.075 mm is mineral powder, the aggregate with a particle size of 0.075-4.75 mm is stone, and the aggregate with a particle size of 4.75-9.5 mm comprises: calcined bauxite, ceramic aggregate, and stone.

[0009] The raw material composition of the anti-skid surface layer asphalt mixture comprises, in percentage by volume, 10-40% of ceramic granules, 10-40% of calcined bauxite, 10-40% of stone with a particle size of 4.75-9.5mm, 30-50% of stone with a particle size of 0.075-4.75mm, and 3-8% of mineral powder, and 5.5-7.5% of modified asphalt in total mass of the above raw materials.

[0010] Preferably, the raw material composition of the anti-skid surface layer asphalt mixture comprises, in percentage by volume, 11-33% of ceramic granules, 22% of calcined bauxite, 11-33% of stone with a particle size of 4.75-9.5mm, 40% of stone with a particle size of 0.075-4.75mm, and 5% of mineral powder, and 6-6.9% of modified asphalt in total mass of the above raw materials.

[0011] Preferably, the raw material composition of the anti-skid surface layer asphalt mixture comprises, in percentage by volume, 22% of ceramic granules, 22% of calcined bauxite, 11% of stone with a particle size of 4.75-9.5mm, 40% of stone with a particle size of 0.075-4.75mm, and 5% of mineral powder, and 6.5% of modified asphalt in total mass of the above raw materials.

[0012] Preferably, the average roughness R a of the ceramic granules is ≥4μm, the root mean square roughness R q is ≥6μm, and the maximum peak height R z is ≥20μm; and the water absorption of the ceramic granules is ≥6.0%.

[0013] Preferably, the crushing value of the calcined bauxite is ≤12%, and the abrasion value is ≤15%.

[0014] The main chemical composition of the calcined bauxite comprises, in percentage by mass, 50%-60% of Al2O3, <0.8% of CaO, and <2.5% of Fe2O3.

[0015] The calcined bauxite has a mass grade of four, a refractory temperature >1770℃, a specific gravity >2.55g / cm 3 , and a Mohs hardness ≥7.

[0016] Preferably, the crushing value of the composite aggregate of the aggregate with a particle size of 4.75-9.5mm in the anti-skid surface layer asphalt mixture is ≤26%, and the abrasion value is ≤28%.

[0017] Preferably, the modified asphalt is high-viscosity and high-elasticity modified asphalt, the dynamic viscosity of the modified asphalt at 60℃ is >50000Pa·s, and the elastic recovery at 25℃ is ≥95%.

[0018] The apparent relative density of the mineral powder is ≥2.5, the water content is ≤1%, and the hydrophilic coefficient is <1.

[0019] The stone material is neutral or alkaline stone material, and the mass content of SiO2 is not more than 65%.

[0020] Preferably, the stone material is any one or a mixture of two or more of basalt, diabase, diorite and andesite.

[0021] The application provides a preparation method of the anti-skid surface layer asphalt mixture, and comprises the following steps:

[0022] (1) weighing each raw material according to the raw material composition, and reserving;

[0023] (2) heating the modified asphalt to 190-195 DEG C, and reserving;

[0024] (3) mixing calcined bauxite, ceramsite, stone material and mineral powder, and heating to 190-210 DEG C, and reserving;

[0025] (4) mixing the raw materials in step (2) and step (3), and the mixing temperature is 185-190 DEG C, and the anti-skid surface layer asphalt mixture is obtained.

[0026] The application provides application of the anti-skid surface layer asphalt mixture in paving asphalt pavement.

[0027] Beneficial effects:

[0028] The application is based on the differential abrasion principle, the surface texture of the ceramsite is rich, the surface texture is slow to attenuate under the repeated action of automobile load, meanwhile, the calcined bauxite has the characteristics of large hardness, low crushing value, low abrasion value, strong bearing capacity and wear resistance, and the application provides a calcined bauxite / ceramsite composite aggregate anti-skid surface layer asphalt mixture.

[0029] The application composites the two materials of calcined bauxite and ceramsite, fully develops the advantages of the materials, realizes the bauxite / ceramsite asphalt mixture design based on the differential abrasion principle, realizes the difference of the polishing and abrasion of the calcined bauxite, ceramsite and mineral aggregate under the long-term tire load, makes the asphalt pavement still maintain good surface texture and structure under the long-term vehicle tire action, forms the regenerative texture on the road surface, thereby maintaining the surface texture characteristics of the asphalt pavement, making the asphalt pavement have the durability of anti-skid durability and service performance, improving the long-term anti-skid capacity and abrasion resistance of the surface layer of the asphalt pavement, and simultaneously improving the mechanical properties of the asphalt mixture, which is of great significance to improve the driving safety of the expressway.

[0030] The raw material composition of the application comprises: mineral powder with a particle size of 0-0.075 mm, stone with a particle size of 0.075-4.75 mm, calcined bauxite with a particle size of 4.75-9.5 mm, ceramsite and stone. Among them, the stone with a particle size of 4.75-9.5 mm cooperates with the calcined bauxite and the ceramsite to achieve the complementary surface texture of the materials, form the recycled road surface texture structure, and play the bearing and anti-skid roles. The stone with a particle size of 0.075-4.75 mm has the filling main skeleton role in the raw material composition. The mineral powder with a particle size of 0-0.075 mm has the filling gap role in the raw material composition. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. Among these figures:

[0032] Figure 1 It is a schematic diagram of the MTD change of the test piece under different ceramsite contents in embodiment 1 of the application;

[0033] Figure 2 It is a schematic diagram of the surface 3D texture of the test piece under different ceramsite contents in embodiment 1 of the application;

[0034] Figure 3 It is a schematic diagram of the proportion of the serious wear area of the test piece surface under different ceramsite contents in embodiment 1 of the application;

[0035] Figure 4 It is a schematic diagram of the change of the test piece deflection value under different ceramsite contents in embodiment 1 of the application;

[0036] Figure 5 It is a schematic diagram of the test piece rutting test result under different ceramsite contents in embodiment 1 of the application;

[0037] Figure 6 It is a schematic diagram of the test piece low-temperature beam bending test result under different ceramsite contents in embodiment 1 of the application;

[0038] Figure 7 It is a schematic diagram of the test piece immersion Marshall test result under different ceramsite contents in embodiment 1 of the application;

[0039] Figure 8 It is a schematic diagram of the test piece freeze-thaw splitting test result under different ceramsite contents in embodiment 1 of the application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0041] The present application will be described in detail below with examples. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0042] The ceramsite has rich surface texture, and the surface texture of the ceramsite attenuates slowly after repeated action of the tire, but the ceramsite has small hardness, large crushing value and large abrasion value. The calcined bauxite has high hardness, low crushing value and low abrasion value, and has good load bearing capacity and abrasion resistance, and has good physical and chemical properties and relatively small specific gravity. Therefore, the present application takes advantages of respective features of the calcined bauxite and the ceramsite, fully utilizes the rich surface texture of the ceramsite and the high load bearing capacity and abrasion resistance of the calcined bauxite, and applies the calcined bauxite / ceramsite composite aggregate to the anti-skid surface layer asphalt mixture. The two materials have different surface texture attenuation degrees under repeated action of the tire, and form structural texture, so that the asphalt road surface maintains good texture depth and surface texture. The texture depth and texture have good correlation with the anti-skid index, and the texture depth is large and the surface texture is rich, so the anti-skid performance is good. The anti-skid surface layer can maintain the state of rich surface texture, small abrasion and wear loss and high load bearing capacity under long-term action of the wheel load, so as to ensure good anti-skid durability of the asphalt pavement.

[0043] The present application utilizes the porosity and rich surface texture of the ceramsite, and the differential abrasion of the ceramsite and the mineral aggregate after polishing, so as to maintain the texture depth of the surface layer at a high level, improve the long-term anti-skid performance of the surface layer of the asphalt pavement, and ensure driving safety. Meanwhile, the present application utilizes the characteristics of the calcined bauxite, such as large hardness, abrasion resistance and pressure resistance, to improve the mechanical properties of the asphalt mixture.

[0044] The present application provides an anti-skid surface layer asphalt mixture of calcined bauxite / ceramsite composite aggregate aiming at the existing problems, which comprises: aggregate with a particle size of 0-0.075mm, aggregate with a particle size of 0.075-4.75mm, aggregate with a particle size of 4.75-9.5mm, and modified asphalt.

[0045] The aggregate with a particle size of 0-0.075mm is mineral powder, the aggregate with a particle size of 0.075-4.75mm is stone, and the aggregate with a particle size of 4.75-9.5mm comprises: calcined bauxite, ceramsite and stone.

[0046] The raw material composition of the anti-skid surface layer asphalt mixture comprises, in percentage by volume, 10-40% (for example, 10%, 11%, 20%, 22%, 30%, 33% or 40%) of ceramic granules, 10-40% (for example, 10%, 11%, 20%, 22%, 30%, 33% or 40%) of calcined bauxite, 10-40% (for example, 10%, 11%, 20%, 22%, 30%, 33% or 40%) of stone with a particle size of 4.75-9.5 mm, 30-50% (for example, 30%, 35%, 40%, 45% or 50%) of stone with a particle size of 0.075-4.75 mm, 3-8% (for example, 3%, 4%, 5%, 6% or 8%) of mineral powder, and 5.5-7.5% (for example, 5.5%, 6%, 6.2%, 6.5%, 6.9%, 7.0% or 7.5%) of modified asphalt based on the total mass of the above raw materials.

[0047] In the preferred embodiment of the present application, the raw material composition of the anti-skid surface layer asphalt mixture comprises, in percentage by volume, 11-33% (for example, 11%, 22% or 33%) of ceramic granules, 22% of calcined bauxite, 11-33% (for example, 11%, 22% or 33%) of stone with a particle size of 4.75-9.5 mm, 40% of stone with a particle size of 0.075-4.75 mm, 5% of mineral powder, and 6-6.9% (for example, 6%, 6.2%, 6.5% or 6.9%) of modified asphalt based on the total mass of the above raw materials.

[0048] In the preferred embodiment of the present application, the raw material composition of the anti-skid surface layer asphalt mixture comprises, in percentage by volume, 11-33% (for example, 11%, 22% or 33%) of ceramic granules, 22% of calcined bauxite, 11-33% (for example, 11%, 22% or 33%) of stone with a particle size of 4.75-9.5 mm, 40% of stone with a particle size of 0.075-4.75 mm, 5% of mineral powder, and 6-6.9% (for example, 6%, 6.2%, 6.5% or 6.9%) of modified asphalt based on the total mass of the above raw materials.

[0049] In the preferred embodiment of the present application, the raw material composition of the anti-skid surface layer asphalt mixture comprises, in percentage by volume, 11-33% (for example, 11%, 22% or 33%) of ceramic granules, 22% of calcined bauxite, 11-33% (for example, 11%, 22% or 33%) of stone with a particle size of 4.75-9.5 mm, 40% of stone with a particle size of 0.075-4.75 mm, 5% of mineral powder, and 6-6.9% (for example, 6%, 6.2%, 6.5% or 6.9%) of modified asphalt based on the total mass of the above raw materials.

[0050] In the preferred embodiment of the present application, the average roughness R a of the ceramic granules is greater than or equal to 4 μm, the root mean square roughness R q of the ceramic granules is greater than or equal to 6 μm, and the maximum peak height R z of the ceramic granules is greater than or equal to 20 μm.

[0051] In the preferred embodiment of the present application, the crushing value of the calcined bauxite is ≤12%, and the abrasion value is ≤15%.

[0052] The main chemical composition of the calcined bauxite is, in terms of mass percentage, Al2O3 50%-60%, CaO <0.8%, and Fe2O3 <2.5%;

[0053] The calcined bauxite has a mass grade of four, a refractory temperature >1770℃, a specific gravity >2.55g / cm 3 , and a Mohs hardness ≥7.

[0054] In the preferred embodiment of the present application, the crushing value of the composite aggregate of the aggregate with a particle size of 4.75-9.5mm in the anti-skid surface layer asphalt mixture is ≤26%, and the abrasion value is ≤28%.

[0055] In the preferred embodiment of the present application, the modified asphalt is high-viscosity and high-elasticity modified asphalt, the dynamic viscosity of the modified asphalt at 60℃ is >50000Pa·s, and the elastic recovery at 25℃ is ≥95%.

[0056] In the preferred embodiment of the present application, the apparent relative density of the mineral powder is ≥2.5, the water content is ≤1%, and the hydrophilic coefficient is <1.

[0057] In the preferred embodiment of the present application, the stone is neutral or alkaline stone, and the mass content of SiO2 is not more than 65%.

[0058] In the preferred embodiment of the present application, the stone is any one of basalt, diabase, diorite, and andesite, or a mixture of two or more thereof.

[0059] The present application provides a preparation method of an anti-skid surface layer asphalt mixture, comprising the following steps:

[0060] (1) weighing each raw material according to the raw material composition, and reserving;

[0061] (2) heating the modified asphalt to 190-195℃ (for example, 190℃, 192℃, 194℃, or 195℃), and reserving;

[0062] (3) mixing the calcined bauxite, the ceramsite, the stone, and the mineral powder, and heating to 190-210℃ (for example, 190℃, 195℃, 200℃, 205℃, or 210℃), and reserving;

[0063] (4) mixing the raw materials of step (2) and step (3), and the mixing temperature is 185-190℃ (185℃, 186℃, 188℃, or 190℃), and the anti-skid surface layer asphalt mixture is obtained. The mixing time is determined by trial mixing according to the specific circumstances, so that the asphalt uniformly covers the aggregate. The production cycle of each tray is not less than 45s (in which the dry mixing time is not less than 5-10s), and is appropriately prolonged on this basis.

[0064] The application provides application of the anti-skid surface layer asphalt mixture in paving asphalt pavement.

[0065] The asphalt pavement construction in rainy season should meet the following requirements:

[0066] (1) Pay attention to weather forecast, strengthen the contact between the construction site, asphalt mixing plant and weather station, control the construction length, and closely link each process.

[0067] (2) The material transport vehicle and the construction site should be provided with rainproof facilities, and the drainage of the base and the road shoulder should be good.

[0068] The paved asphalt layer should be strictly controlled in traffic, protected, kept clean, not caused to be polluted, and the soil or sundries generated in construction should be strictly prohibited to be stacked on the asphalt layer, and the cement mortar should be strictly prohibited to be made on the paved asphalt layer.

[0069] The anti-skid surface layer asphalt mixture of calcined bauxite / ceramic particle composite aggregate, the preparation method and the application thereof will be described in detail through specific examples.

[0070] The raw materials used in the following examples are as follows:

[0071] The particle size of the ceramic particle is 4.75-9.5 mm, the average value R a of the roughness is 6.6371 μm, the root mean square R q of the roughness is 8.2387 μm, and the maximum peak height R z is 26.6914 μm; the water absorption rate of the ceramic particle is ≥6.0%.

[0072] The ceramic particle is shale ceramic particle.

[0073] The crushing value of the calcined bauxite is ≤12%, the abrasion value is ≤15%, the particle size is 4.75-9.5 mm, the average value R a of the roughness is 2.6757 μm, the root mean square R q of the roughness is 3.4906 μm, and the maximum peak height R z is 13.8006 μm.

[0074] The crushing value is in accordance with the standard of JTG E42-2005 Highway Engineering Aggregate Test Procedures, and the abrasion value is in accordance with the standard of JTG E42-2005 Highway Engineering Aggregate Test Procedures.

[0075] The main chemical composition of the calcined bauxite is as follows in terms of mass percentage: Al2O3 50%-60%, CaO <0.8%, and Fe2O3 <2.5%.

[0076] The calcined bauxite has a quality grade of four, an appearance color of gray, a refractory temperature of >1770℃, and a specific gravity of >2.55g / cm 3 , and a Mohs hardness of ≥7.

[0077] The basalt has a particle size of 0.075-4.75mm and 4.75-9.5mm, and a roughness average value R a of 2.6602μm, a roughness root mean square R q of 4.5136μm, and a maximum peak height R z of 12.7228μm.

[0078] The basalt has an apparent relative density of ≥2.60 and a mass content of SiO2 of 45-52%.

[0079] In the anti-skid surface layer asphalt mixture, the composite aggregate (calcined bauxite, ceramsite and basalt) of the aggregate with a particle size of 4.75-9.5mm has a crushing value of ≤26% and an abrasion value of ≤28%.

[0080] The modified asphalt is a high-viscosity and high-elasticity modified asphalt, which has a dynamic viscosity of >50000Pa·s at 60℃, an elastic recovery of ≥95% at 25℃, a penetration (25℃, 5s, 100g) of 30-60(0.1mm), a softening point (T R&B ) of ≥90℃, a flash point of ≥230℃, a solubility (trichloroethylene) of ≥99%, and a complex shear modulus (G*) of ≥10kPa at 60℃.

[0081] The mineral powder has a particle size of 0-0.075mm, an apparent relative density of ≥2.5, a water content of ≤1%, a hydrophilic coefficient of <1, and a plasticity index of <4%.

[0082] Example 1

[0083] The embodiment provides an anti-skid surface layer asphalt mixture of calcined bauxite / ceramsite composite aggregate, which comprises aggregate with a particle size of 0-0.075mm, aggregate with a particle size of 0.075-4.75mm, aggregate with a particle size of 4.75-9.5mm, and high-viscosity and high-elasticity modified asphalt.

[0084] The aggregate with a particle size of 0-0.075mm is mineral powder, the aggregate with a particle size of 0.075-4.75mm is basalt, and the aggregate with a particle size of 4.75-9.5mm comprises calcined bauxite, ceramsite and basalt.

[0085] The experiments are carried out by selecting 0%, 20%, 40% and 60% of the four dosages of ceramsite in the volume percentage of the aggregate with a particle size of 4.75-9.5mm.

[0086] The anti-skid surface layer asphalt mixture of the calcined bauxite / ceramsite composite aggregate with 0% ceramsite includes, in terms of volume percentage, 0% ceramsite with a particle size of 4.75-9.5 mm, 22% calcined bauxite with a particle size of 4.75-9.5 mm, 33% basalt with a particle size of 4.75-9.5 mm, 5% mineral powder with a particle size of 0-0.075 mm, 40% basalt with a particle size of 0.075-4.75 mm, and 6.0% high-viscosity and high-elasticity modified asphalt accounting for 6.0% of the total mass of the above raw materials.

[0087] The anti-skid surface layer asphalt mixture of the calcined bauxite / ceramsite composite aggregate with 20% ceramsite includes, in terms of volume percentage, 11% ceramsite with a particle size of 4.75-9.5 mm, 22% calcined bauxite with a particle size of 4.75-9.5 mm, 22% basalt with a particle size of 4.75-9.5 mm, 5% mineral powder with a particle size of 0-0.075 mm, 40% basalt with a particle size of 0.075-4.75 mm, and 6.2% high-viscosity and high-elasticity modified asphalt accounting for 6.2% of the total mass of the above raw materials.

[0088] The anti-skid surface layer asphalt mixture of the calcined bauxite / ceramsite composite aggregate with 40% ceramsite includes, in terms of volume percentage, 22% ceramsite with a particle size of 4.75-9.5 mm, 22% calcined bauxite with a particle size of 4.75-9.5 mm, 11% basalt with a particle size of 4.75-9.5 mm, 5% mineral powder with a particle size of 0-0.075 mm, 40% basalt with a particle size of 0.075-4.75 mm, and 6.5% high-viscosity and high-elasticity modified asphalt accounting for 6.5% of the total mass of the above raw materials.

[0089] The anti-skid surface layer asphalt mixture of the calcined bauxite / ceramsite composite aggregate with 60% ceramsite includes, in terms of volume percentage, 33% ceramsite with a particle size of 4.75-9.5 mm, 22% calcined bauxite with a particle size of 4.75-9.5 mm, 0% basalt with a particle size of 4.75-9.5 mm, 5% mineral powder with a particle size of 0-0.075 mm, 40% basalt with a particle size of 0.075-4.75 mm, and 6.9% high-viscosity and high-elasticity modified asphalt accounting for 6.9% of the total mass of the above raw materials.

[0090] The preparation method of the anti-skid surface layer asphalt mixture includes the following steps:

[0091] (1) The raw materials are weighed according to the raw material composition and prepared for use;

[0092] (2) The modified asphalt is heated to 190℃ and prepared for use;

[0093] (3) The calcined bauxite, ceramsite, stone and mineral powder are mixed and heated to 190℃ and prepared for use;

[0094] (4) Step (2) and step (3) raw materials are mixed, the mixing temperature is 185℃, the mixing time is 45s, to get.

[0095] Application Example 1

[0096] The asphalt mixture obtained in Example 1 with different volume ratios (0%, 20%, 40%, and 60%) of ceramsite with a particle size of 4.75-9.5 mm was tested for related performance:

[0097] (1) Mean texture depth (MTD) test

[0098] MTD (mean texture depth) is the average texture depth. The test method is specified in the Technical Index Requirements of Highway Subgrade and Pavement Field Test Procedures (JTG 3450-2019) according to the annual average rainfall.

[0099] The MTD of the asphalt mixture with different volume ratios of ceramsite in Example 1 was tested, and the results are shown in Figure 1 . As can be seen from Figure 1 , when the content of calcined bauxite with a particle size of 4.75-9.5 mm is 40%, the texture depth of the specimen is greater than 0.9 mm regardless of the amount of ceramsite, which is significantly better than that of general mineral mixture. Among them, when the ceramsite content is 40%, the asphalt mixture has the best surface texture depth, and the texture depth decreases slowly with the increase of tire action times, and the texture depth can still be maintained at 1.1 mm after 12000 times of action, indicating that when the content of calcined bauxite with a particle size of 4.75-9.5 mm and ceramsite is 40%, the formed recycled texture structure is significant, and the long-term skid resistance is good.

[0100] (2) Surface 3D texture test

[0101] The surface texture of the asphalt mixture with different volume ratios of ceramsite in Example 1 was scanned using the pavement PATT-II anti-skid texture tester, and the 3D imaging of the surface when the polishing times were 12000 times is shown in Figure 2 . The blue area is selected and the color tolerance is adjusted to 200 in the image processing software, and the proportion of blue pixel blocks (severe wear area) is calculated to get Figure 3 .

[0102] According to Figure 2It can be seen that after 12000 times of polishing, the middle part of the test piece of the asphalt mixture with four different ceramsite contents appears to have a smaller structure depth. Among them, the degree of wear: 0%>20%>40%>60%, the test piece with 0% ceramsite content has mostly dark blue, indicating that the surface of the test piece without ceramsite is severely worn. The reason for this phenomenon is that there are a large number of pores in the ceramsite, which can enhance the overall polishing resistance of the mixture, so after increasing the ceramsite content, the polishing resistance of the test piece is getting better and better.

[0103] According to Figure 3 It can be seen that after 12000 times of polishing, the test piece surface of the asphalt mixture with four different ceramsite contents is severely worn: 0%>20%>40%>60%.

[0104] (3) Determination of deflection value

[0105] The deflection value is the friction coefficient value of the road surface under wet conditions, which is measured by a pendulum friction coefficient tester. According to the test requirements of the current specification "Highway Roadbed and Pavement Field Test Specification" (JTG 3450-2019), the deflection value change of the pavement test piece of the asphalt mixture with different volume ratios of ceramsite content in Example 1 in the polishing test is as shown in Figure 4 .

[0106] According to Figure 4 It can be seen that the deflection value of the ceramsite asphalt mixture gradually decreases with the increase of the polishing times, and the deflection value is: 40%>0%>20%>60%, and the extreme value is 2BPN. The asphalt mixture test piece with 40% ceramsite content has the smallest structure depth attenuation in the polishing test, and its structure depth can still reach 1.1mm after 12000 times of tire action. There is a difference in wear between calcined bauxite and ceramsite, forming a regenerative surface structure, which shows higher structure depth and larger deflection value. Both of these two indicators are used to evaluate the anti-skid ability of the road. Moreover, the polishing frequency reaching the stable node when the ceramsite content is 0% is 4000 times, while the polishing frequency reaching the stable node when the ceramsite content is 20% and 40% is 12000 times, and the polishing frequency reaching the stable node when the ceramsite content is 60% is greater than 12000 times. Therefore, after adding ceramsite and calcined bauxite, the polishing resistance of the asphalt mixture has been significantly improved.

[0107] (4) Rutting test

[0108] According to the test requirements of the current specification "Highway Engineering Asphalt and Asphalt Mixture Test Specification" (JTG E20-2011), the rutting test results of the asphalt mixture with different volume ratios of ceramsite content are as shown in Figure 5 . According to Figure 5It can be seen that the anti-rutting ability of the asphalt mixture increases with the increase of the ceramsite content. Dynamic stability: 40%>20%>0%>60%, the high temperature stability is the best when the ceramsite content is 40%, and the high temperature performance will be poor when the content exceeds 40%. This is because the ceramsite is porous and has low strength, and when the ceramsite content is 60%, the main skeleton of the asphalt mixture is mainly borne by the ceramsite, but the ceramsite has low hardness and is easy to be crushed. The rutting test is used to evaluate the bearing capacity and deformation resistance of the asphalt pavement at high temperature, so when the ceramsite content is greater than 40%, the bearing capacity of the asphalt mixture specimen decreases, the ceramsite is easy to be crushed under the action of the steel wheel, the gradation changes, the dynamic stability value decreases, and the high temperature performance is poor. At the same time, the calcined bauxite has the characteristics of high hardness, small crushing value, strong bearing capacity and high temperature resistance, so the asphalt mixture of the present application has good high temperature stability and strong resistance to permanent deformation.

[0109] (5) Low temperature beam bending test

[0110] According to the test requirements of the current specification "Highway Engineering Asphalt and Asphalt Mixture Test Procedure" (JTG E20-2011), the low temperature beam bending test results of the asphalt mixture with different volume ratios of ceramsite content are shown in Table 1. According to the current specification requirements, the low temperature bending test failure strain of modified asphalt mixture in winter severe cold area should be not less than 3000με, and the ceramsite contents of 20% and 40% can meet the specification requirements. Figure 6 、Table 1 shows the low temperature beam bending test results of the asphalt mixture with different volume ratios of ceramsite content. Figure 6 It can be seen that with the increase of the ceramsite content, the low temperature performance of the ceramsite asphalt mixture increases first and then decreases. The maximum bending tensile strain is the largest when the ceramsite content is 20%. According to the current specification requirements, the low temperature bending test failure strain of modified asphalt mixture in winter severe cold area should be not less than 3000με, and the ceramsite contents of 20% and 40% can meet the specification requirements.

[0111] Table 1 Low temperature beam bending test results of asphalt mixture with different volume ratios of ceramsite content

[0112] Ceramsite content (%) Flexural tensile strength (Mpa) Maximum flexural tensile strain (με) Flexural stiffness modulus (MPa) 0 13.32 3160 3941 20 12.01 3444 3528 40 11.38 3132 3681 60 10.96 2824 3896

[0113] (6) Immersion Marshall test

[0114] According to the test requirements of the current specification "Highway Engineering Asphalt and Asphalt Mixture Test Procedure" (JTG E20-2011), the immersion Marshall test results of the asphalt mixture with different volume ratios of ceramsite content are shown in Table 2. According to the current specification requirements, the residual stability of the immersion Marshall test should be not less than 80%, and the immersion Marshall test results of the asphalt mixture with different ceramsite contents meet the specification requirements. Figure 7 Table 2 Immersion Marshall test results of asphalt mixture with different volume ratios of ceramsite content

[0115]

[0116]

[0117] ​MS: the stability before immersion; MS1: the stability after immersion.

[0118] (7) Freeze-thaw splitting test

[0119] According to the test requirements of the current specification “Highway Engineering Asphalt and Asphalt Mixture Test Specification” (JTG E20-2011), the freeze-thaw splitting test results of the asphalt mixture with different volume ratios of ceramsite content are shown in Table 3. According to the requirements of the current specification, the freeze-thaw splitting strength ratio is not less than 75%, whether ceramsite is added or not, the freeze-thaw splitting strength ratio of the asphalt mixture meets the requirements of the specification, and with the increase of the ceramsite content, the splitting strength ratio of the test piece as a whole shows a slightly rising trend. Figure 8

[0120] Table 3 Freeze-thaw splitting test results of asphalt mixture with different volume ratios of ceramsite content

[0121]

[0122] R: the un-frozen splitting tensile strength; R T1 R: the frozen splitting tensile strength. T2 R: the frozen splitting tensile strength.

[0123] From the above tests, it can be seen that the anti-skid performance and high-temperature stability of the asphalt mixture after adding ceramsite and calcined bauxite are obviously improved, while meeting the requirements of road performance. When the content of ceramsite and calcined bauxite is 40%, the anti-skid performance and high-temperature stability of the asphalt mixture are optimal, while the low-temperature performance and water stability meet the requirements of the specification, it is recommended to use ceramsite and calcined bauxite with a content of 40%.

[0124] Example 2

[0125] The embodiment provides an anti-skid surface layer asphalt mixture of calcined bauxite / ceramsite composite aggregate, which comprises: aggregate with a particle size of 0-0.075 mm, aggregate with a particle size of 0.075-4.75 mm, aggregate with a particle size of 4.75-9.5 mm, and high-viscosity high-elasticity modified asphalt.

[0126] The aggregate with a particle size of 0-0.075 mm is mineral powder, the aggregate with a particle size of 0.075-4.75 mm is basalt, and the aggregate with a particle size of 4.75-9.5 mm comprises: calcined bauxite, ceramsite and basalt.

[0127] The volume percentage of ceramsite in the aggregate with a particle size of 4.75-9.5 mm is 40%, the volume percentage of calcined bauxite in the aggregate with a particle size of 4.75-9.5 mm is 40%, and the oilstone ratio (i.e. the ratio of the mass of high-viscosity high-elasticity modified asphalt to the total mass of aggregate with different particle sizes) is changed, and the specific conditions are as follows:

[0128] ​(1) The anti-skid surface layer asphalt mixture of calcined bauxite / ceramic composite aggregate, the raw material composition includes, in volume percentage: 22% of ceramic particles with particle size of 4.75-9.5 mm, 22% of calcined bauxite with particle size of 4.75-9.5 mm, 11% of basalt with particle size of 4.75-9.5 mm, 5% of mineral powder with particle size of 0-0.075 mm, 40% of basalt with particle size of 0.075-4.75 mm, and 5.5% of high-viscosity and high-elasticity modified asphalt accounting for 5.5% of the total mass of the above raw materials.

[0129] (2) The anti-skid surface layer asphalt mixture of calcined bauxite / ceramic composite aggregate, the raw material composition includes, in volume percentage: 22% of ceramic particles with particle size of 4.75-9.5 mm, 22% of calcined bauxite with particle size of 4.75-9.5 mm, 11% of basalt with particle size of 4.75-9.5 mm, 5% of mineral powder with particle size of 0-0.075 mm, 40% of basalt with particle size of 0.075-4.75 mm, and 6.0% of high-viscosity and high-elasticity modified asphalt accounting for 6.0% of the total mass of the above raw materials.

[0130] (3) The anti-skid surface layer asphalt mixture of calcined bauxite / ceramic composite aggregate, the raw material composition includes, in volume percentage: 22% of ceramic particles with particle size of 4.75-9.5 mm, 22% of calcined bauxite with particle size of 4.75-9.5 mm, 11% of basalt with particle size of 4.75-9.5 mm, 5% of mineral powder with particle size of 0-0.075 mm, 40% of basalt with particle size of 0.075-4.75 mm, and 6.5% of high-viscosity and high-elasticity modified asphalt accounting for 6.5% of the total mass of the above raw materials.

[0131] (4) The anti-skid surface layer asphalt mixture of calcined bauxite / ceramic composite aggregate, the raw material composition includes, in volume percentage: 22% of ceramic particles with particle size of 4.75-9.5 mm, 22% of calcined bauxite with particle size of 4.75-9.5 mm, 11% of basalt with particle size of 4.75-9.5 mm, 5% of mineral powder with particle size of 0-0.075 mm, 40% of basalt with particle size of 0.075-4.75 mm, and 7.0% of high-viscosity and high-elasticity modified asphalt accounting for 7.0% of the total mass of the above raw materials.

[0132] (5) The anti-skid surface layer asphalt mixture of calcined bauxite / ceramic composite aggregate, the raw material composition includes, in volume percentage: 22% of ceramic particles with particle size of 4.75-9.5 mm, 22% of calcined bauxite with particle size of 4.75-9.5 mm, 11% of basalt with particle size of 4.75-9.5 mm, 5% of mineral powder with particle size of 0-0.075 mm, 40% of basalt with particle size of 0.075-4.75 mm, and 7.5% of high-viscosity and high-elasticity modified asphalt accounting for 7.5% of the total mass of the above raw materials.

[0133] The preparation method of the anti-skid surface layer asphalt mixture includes the following steps:

[0134] (1) Weigh each raw material according to the composition of the raw material, and prepare for use;

[0135] (2) Heat the modified asphalt to 190℃, and prepare for use;

[0136] (3) Mix calcined bauxite, ceramsite, stone and mineral powder, and heat to 190℃, and prepare for use;

[0137] (4) Mix the raw materials of step (2) and step (3), the mixing temperature is 185℃, and the mixing time is 45s, and the porous ceramsite asphalt mixture is obtained.

[0138] Application Example 2

[0139] According to the test requirements of the current specification "Highway Engineering Asphalt and Asphalt Mixture Test Procedures" (JTG E20-2011), the Marshall mix ratio test of the asphalt dosage of 5.5%, 6.0%, 6.5%, 7.0% and 7.5% in Example 2 was carried out at 190℃, and the results are shown in Table 4.

[0140] Table 4 Marshall test results

[0141]

[0142] According to the test results of the anti-skid performance and road performance test of the test pieces with different ceramsite and asphalt dosages, the statistical analysis shows that when the porous ceramsite dosage is 40%, the calcined bauxite dosage is 40%, and the asphalt dosage is 6.5%, the anti-skid performance, water stability and high temperature stability of the porous ceramsite asphalt mixture reach the best balance point.

[0143] The above is only the preferred embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A skid-resistant surface asphalt mixture based on calcined bauxite / ceramsite composite aggregate, characterized in that, include: Aggregates with a particle size of 0-0.075mm, aggregates with a particle size of 0.075-4.75mm, aggregates with a particle size of 4.75-9.5mm, and modified asphalt; The aggregate with a particle size of 0-0.075mm is mineral powder, the aggregate with a particle size of 0.075-4.75mm is stone, and the aggregate with a particle size of 4.75-9.5mm includes calcined bauxite, ceramsite, and stone; the average roughness R of the ceramsite is... a ≥4μm, root mean square roughness R q ≥6μm, maximum peak height R z ≥20μm; the water absorption rate of the ceramsite is ≥6.0%; the crushing value of the calcined bauxite is ≤12%, the abrasion value is ≤15%, and the Mohs hardness is ≥7; By volume percentage, the raw material composition of the anti-skid surface asphalt mixture includes: 10-40% ceramsite, 10-40% calcined bauxite, 10-40% aggregate with a particle size of 4.75-9.5mm, 30-50% aggregate with a particle size of 0.075-4.75mm, and 3-8% mineral powder, as well as modified asphalt accounting for 5.5-7.5% of the total mass of the above raw materials.

2. The anti-skid surface asphalt mixture as described in claim 1, characterized in that, By volume percentage, the raw material composition of the anti-skid surface asphalt mixture includes: 11-33% ceramsite, 22% calcined bauxite, 11-33% aggregate with a particle size of 4.75-9.5mm, 40% aggregate with a particle size of 0.075-4.75mm, and 5% mineral powder, as well as modified asphalt accounting for 6-6.9% of the total mass of the above raw materials.

3. The anti-skid surface asphalt mixture as described in claim 2, characterized in that, By volume percentage, the raw material composition of the anti-skid surface asphalt mixture includes: 22% ceramsite, 22% calcined bauxite, 11% aggregate with a particle size of 4.75-9.5mm, 40% aggregate with a particle size of 0.075-4.75mm, and 5% mineral powder, as well as modified asphalt accounting for 6.5% of the total mass of the above raw materials.

4. The anti-skid surface asphalt mixture as described in claim 1, characterized in that, The main chemical composition of calcined bauxite, by mass percentage, is: Al2O3 50%-60%, CaO <0.8% and Fe2O3 <2.5%; The calcined bauxite is grade four, with a refractoriness temperature >1770℃ and a specific gravity >2.55g / cm³. 3 .

5. The anti-skid surface asphalt mixture as described in claim 1, characterized in that, In the anti-skid surface asphalt mixture, the composite aggregate with aggregates of 4.75-9.5mm in particle size has a crushing value ≤26% and an abrasion value ≤28%.

6. The anti-skid surface asphalt mixture as described in claim 1, characterized in that, The modified asphalt is a high-viscosity, high-elasticity modified asphalt, with a dynamic viscosity of >50000 Pa·s at 60℃ and an elastic recovery of ≥95% at 25℃; The mineral powder has an apparent relative density ≥2.5, a water content ≤1%, and a hydrophilicity coefficient <1; The stone is a neutral or alkaline stone with a SiO2 content of no more than 65% by mass.

7. The anti-skid surface asphalt mixture as described in claim 6, characterized in that, The stone material is any one or a mixture of two or more of the following: basalt, diabase, diorite, and andesite.

8. The method for preparing the anti-skid surface asphalt mixture according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Weigh each raw material according to its composition and set aside; (2) Heat the modified asphalt to 190-195℃ and set aside; (3) Mix calcined bauxite, ceramsite, stone and mineral powder, heat to 190-210℃, and set aside; (4) Mix the raw materials from steps (2) and (3) at a temperature of 185-190℃ to obtain the final product.

9. The application of the anti-skid surface asphalt mixture as described in any one of claims 1-7 in the paving of asphalt pavements.

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