Recycled aggregate based on waste refractory material, preparation method of recycled aggregate and anti-skid pavement

Abstract

The invention relates to the technical field of road engineering materials, in particular to a recycled aggregate based on a waste refractory material, a preparation method of the recycled aggregate and an anti-skid pavement, the recycled aggregate is prepared from the waste refractory material, and the waste refractory material is a high-alumina refractory material; the particle size of the regenerated aggregate is less than or equal to 9.5 mm, the angularity is greater than or equal to 3200 AIMS units, the Form2D index is greater than or equal to 7.5, the sphericity is 0.6-0.7, and the ratio of the flatness to the slenderness is greater than or equal to 2.5. The regenerated aggregate is derived from a waste refractory material, macroscopically regulated and controlled through aggregate particle size grading, meanwhile, the morphology of the regenerated aggregate is limited, the synergistic effect of the microstructure and the macroscopic structure of the aggregate is fully considered, and the high-performance regenerated aggregate is obtained through precise screening and serves as a natural raw material or a substitute aggregate of calcined bauxite; the recycled aggregate is used for the anti-skid surface layer, and the technical specification requirements of the anti-skid surface layer of highway engineering are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road engineering materials, in particular to recycled aggregate based on waste refractory material and a preparation method thereof and anti-skid pavement. BACKGROUND

[0002] Refractory material is a key material for high-temperature industry and a resource-consuming industry. Due to the large amount of refractory material, especially high-alumina refractory material, the used waste refractory material has been mostly landfilled or degradedly used as a refractory raw material for a long time, and the utilization value is low. More than ten million tons of waste refractory material are generated every year, and only less than 10% of them are used at a low value. A large amount of accumulation or landfill will cause soil / water pollution.

[0003] The aggregate of high anti-skid and wear-resistant pavement is usually mainly made of basalt, limestone, granite and calcined bauxite aggregate. The natural raw material resources are consumed and the mining cost is high. The cost of calcined bauxite aggregate is high, and the production energy consumption is high. Therefore, it is an important task to find a substitute for natural wear-resistant aggregate or calcined bauxite aggregate. The waste refractory material is expected to be used for high anti-skid and wear-resistant pavement aggregate due to its large volume, high alumina content and good wear resistance.

[0004] The existing recycled aggregate based on waste refractory material is mostly focused on the basic application of recycled aggregate. The recycled aggregate is not optimized for the anti-skid demand of pavement. The friction coefficient of the pavement decreases by more than 40% after the recycled aggregate is applied to the pavement for 5 years, especially under heavy traffic, which leads to anti-skid failure. The anti-skid potential of the recycled aggregate has not been fully tapped. SUMMARY

[0005] The present application aims to solve the problem that the existing recycled aggregate is not optimized for the anti-skid demand of pavement, the friction coefficient of the pavement decreases greatly after service, and the anti-skid failure is caused. The present application provides a recycled aggregate based on waste refractory material and a preparation method thereof and anti-skid pavement.

[0006] In a first aspect, the present application provides a recycled aggregate based on waste refractory material, which is prepared from waste refractory material. The particle size of the recycled aggregate is ≤9.5mm, the angularity is ≥3200 AIMS units, the Form2D index is ≥7.5, the sphericity is 0.6-0.7, and the flatness and thin length ratio is ≥2.5.

[0007] As a preferred scheme of the present application, the waste refractory material is high-alumina refractory material.

[0008] As a preferred embodiment of the present invention, the waste refractory material includes at least one of silicon-mullite bricks, corundum-magnesium-alumina spinel castables, and high-voltage electrical porcelain. High-voltage electrical porcelain refers to waste products, substandard products, and waste materials generated during the production of high-voltage electrical porcelain due to imperfect processes or unqualified testing, as well as waste materials generated during use due to damage.

[0009] As a preferred embodiment of the present invention, the silicon-mullite brick contains more than 60% Al2O3 and more than 20% SiO2 by mass percentage; the corundum-magnesium-aluminum spinel castable contains more than 70% Al2O3 and more than 8% MgO; and the high-voltage electrical porcelain contains more than 45% Al2O3 and more than 40% SiO2.

[0010] As a preferred embodiment of the present invention, the phases of the silicon-mullite brick include corundum, mullite and silicon carbide, wherein the corundum content is greater than 45%; the phases of the corundum-magnesium aluminum spinel castable include corundum and magnesium aluminum spinel, wherein the corundum content is greater than 60%; the phases of the high voltage electrical porcelain include corundum, mullite and silicon carbide, wherein the corundum content is greater than 60%.

[0011] As a preferred embodiment of the present invention, the polished value PSV of the recycled aggregate is ≥55BPN; the Los Angeles abrasion value is ≤20%; and the crushing value is ≤15%.

[0012] As a preferred embodiment of the present invention, the particle size of the recycled aggregate is ≤4.75mm.

[0013] In a second aspect, the present invention provides a method for preparing recycled aggregates based on waste refractory materials, comprising the following steps: S1. Select the waste refractory materials; S2. The waste refractory material is crushed using a jaw crusher, with the feed particle size ≤100mm and the discharge particle size ≤40mm. S3. The waste refractory material after S2 crushing is crushed using an impact crusher to control the discharge particle size to ≤20mm. S4. The waste refractory material after S3 crushing is crushed using a cone crusher to control the discharge particle size to ≤9.5mm; S5. Screening is performed to obtain the recycled aggregate with different particle size distributions.

[0014] As a preferred embodiment of the present invention, after screening, the recycled aggregate is soaked and strengthened.

[0015] As a preferred scheme of the present application, the discharge port diameter of the jaw crusher is 65-75 mm, and the frequency of the moving jaw is 80-120 times / min. The size of the discharge port of the jaw crusher is in the range of 65-75 mm, which determines the size of the crushed material, and the appropriate discharge port diameter can meet the requirements of different productions on the particle size of the finished material; the moving jaw swings 80-120 times per minute, and the moving jaw is a key component of the jaw crusher, and its swing frequency affects the crushing efficiency and effect. Through the limitation of the above parameters, the damage rate of the material to be crushed is ≤15%, and the production efficiency is ≥80 t / h.

[0016] As a preferred scheme of the present application, the impact crusher adopts a double-layer plate hammer spacing design, the first layer of plate hammer spacing is 30-40 mm, and the second layer of plate hammer spacing is 20-30 mm, so that the needle-like content of the recycled aggregate is ≤12%, and the water absorption rate is reduced to below 5%. The plate hammer is a key component of the impact crusher, and when the crusher is running, the plate hammer rotates at high speed, and the material entering the crushing cavity collides with the plate hammer and is crushed. The first layer of larger plate hammer spacing first preliminarily crushes the material, and the larger blocks of material are crushed into relatively smaller particles; the material after the first layer of crushing enters the second layer of crushing area, and the smaller plate hammer spacing can further finely crush the material, so that the particle size of the material is more uniform.

[0017] As a preferred scheme of the present application, the inclination angle of the circular vibrating screen of the cone crusher is 20-24°, and the amplitude is 3-4.5 mm, so that the particle size purity of the aggregate is ≥95%.

[0018] In a third aspect, the present application provides an anti-skid and wear-resistant pavement, which comprises a base layer, a bonding layer and a wearing layer arranged in sequence on the base layer, and the wearing layer is composed of the recycled aggregate based on waste refractory material or the recycled aggregate obtained by the preparation method based on waste refractory material.

[0019] As a preferred scheme of the present application, the bonding layer is composed of a bonding agent, and the bonding agent comprises at least one of an epoxy resin bonding agent, a rosin ester bonding agent, a polyurethane bonding agent, an acrylic resin bonding agent and a polyester resin bonding agent. Among them, the epoxy resin curing agent is widely used in the anti-skid and wear-resistant pavement due to its good adhesion, long maintenance time, corrosion resistance and other advantages.

[0020] As a preferred scheme of the present application, the base layer is a concrete structure, and the thickness of the base layer is 15-30 cm.

[0021] As a preferred scheme of the present application, the thickness of the wearing layer is 1.5-4 cm.

[0022] As a preferred scheme of the present application, the thickness of the adhesive layer is 0.5 cm to 1.5 cm, which can ensure that the recycled aggregate uniformly covers the adhesive layer.

[0023] Compared with the prior art, the present application has the following beneficial effects: 1. The present application provides a recycled aggregate based on waste refractory material, which is derived from waste refractory material, and is regulated in macroscopic particle size grading, while the morphology of the recycled aggregate is limited, including the angularity, Form 2D two-dimensional shape index, sphericity, flatness and length ratio of the aggregate, fully considering the synergistic effect of the micro-morphology and macro-structure of the aggregate, and accurately screening high-performance recycled aggregate as a substitute for natural raw materials or calcined bauxite; when the recycled aggregate is used for anti-skid surface layer, after the anti-skid performance attenuation test, the dynamic friction coefficient is 0.85 after 50,000 times of abrasion, and the dynamic friction coefficient is 0.808 after 140,000 times of abrasion, and the attenuation rate is only 72% of basalt, meeting the technical specification requirements of highway engineering anti-skid surface layer.

[0024] 2. The present application provides a recycled aggregate based on waste refractory material for anti-skid and wear-resistant pavement, which realizes the resource utilization of waste materials, improves the anti-skid performance, durability and service life of the pavement, reduces the construction cost and environmental load of the road, and is suitable for high-grade highways, heavy traffic road sections and other scenes, and has significant economic, environmental and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The phase composition and ingredient ratio of the three kinds of recycled aggregates; Figure 2 The test data of the damage rate (a) and production capacity (b) of the original aggregate with different discharge port diameters; Figure 3 The test data of the damage rate (a) and production capacity (b) of the aggregate with different moving jaw working frequencies; Figure 4 The AIMS index value range and division basis diagram; Figure 5 The change trend of the average angularity of different aggregates with the number of abrasion times; Figure 6 The average angularity change graph of different aggregates before and after Los Angeles abrasion; Figure 7 The change trend graph of the average Form 2D of different aggregates with the number of abrasion times; Figure 8 The average Form 2D change graph of different aggregates before and after Los Angeles abrasion; Figure 9 The change trend graph of the average texture with the number of abrasion times; Figure 10Figure 8 is a graph showing the average texture change of Los Angeles abrasion before and after; Figure 11 Figure 9 is a graph showing the average sphericity trend with the number of abrasion; Figure 12 Figure 10 is a graph showing the average sphericity change of Los Angeles abrasion before and after; Figure 13 Figure 11 is a graph showing the average F:E trend with the number of abrasion for different aggregates; Figure 14 Figure 12 is a graph showing the average F:E change of Los Angeles abrasion before and after for different aggregates; Figure 15 Figure 13 is a photograph of the HFST specimen; Figure 16 Figure 14 is a graph showing the dynamic friction coefficient decay curve (a) μ 40 ; (b) μ 60 ; Figure 17 Figure 15 is a graph showing the MPD decay curve for different aggregates; Figure 18 Figure 16 is a graph showing the three-dimensional topography and plan view of different HFST after the three-wheel abrasion test; Figure 19 Figure 17 is a graph showing the roughness of the recycled aggregate surface. DETAILED DESCRIPTION

[0026] The application will be further described below in conjunction with specific embodiments. However, it should not be understood that the scope of the above-mentioned subject matter of the application is limited to the following embodiments, and any technology implemented based on the content of the application falls within the scope of the application.

[0027] In the description of the specific embodiments of the application, the orientation or position relationship terms such as "up", "down", "left", "right", "center", "inner", "outer" and the like appearing in the description are based on the orientation or position relationship expressed in the drawings, or the orientation or position relationship of the product / equipment / device of the application when it is usually used. These orientation or position relationship terms are only used to facilitate the description of the application scheme or simplify the description in the specific embodiments, to facilitate the quick understanding of the scheme by the technicians, and are not intended to indicate or imply that a specific device / component / element must have a specific orientation or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the application.

[0028] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel", "coaxial" and the like appear in the terms, it does not mean that the corresponding device / component / element is absolutely horizontal or vertical or overhanging or parallel or coaxial, but can be slightly inclined or deviated, as long as it does not affect the normal function of the related component. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined; "coaxial" means that two components are coaxially arranged as much as possible, and move in a coaxial or approximately coaxial manner when the relative position changes. Alternatively, it can be simplified to understand that the corresponding device / component / element is arranged in the "horizontal", "vertical", "overhanging", "parallel", "coaxial" and the like, and can have an error / deviation of ±10% relative to the corresponding direction, more preferably an error / deviation of ±8%, more preferably an error / deviation of ±6%, more preferably an error / deviation of ±5%, more preferably an error / deviation of ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present application.

[0029] In addition, the terms "first", "second", "third" and the like in the terms are only used to distinguish the same or similar components for description, and should not be understood as emphasizing or implying the relative importance of the specific components.

[0030] In addition, in the description of the embodiments of the present application, "several", "a plurality of", "several" represent at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. in any case, and even more than 9.

[0031] In addition, in the description of the technical scheme of the present application, unless otherwise specified / limited / limited, the terms "arrangement", "installation", "connection", "connection", "provided with", "laid", "arrangement" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, which can be welding, riveting, bolting, screwing and other commonly used connection means in the art. The connection can be mechanical connection, electrical connection or communication connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the communication between two elements.

[0032] Example 1 The present embodiment provides a recycled aggregate based on waste refractory material, the recycled aggregate is prepared from waste refractory material, and the waste refractory material is high-alumina refractory material; the particle size of the recycled aggregate is ≤9.5mm, the angularity is ≥3200 AIMS units, the Form2D index is ≥7.5, the sphericity is 0.6-0.7, and the flatness and thin length ratio is ≥2.5.

[0033] Three kinds of waste refractory materials are selected to prepare recycled aggregates, namely silicon-mullite brick (silicon carbide-mullite brick), castable, and high-voltage porcelain. In this embodiment, the silicon-mullite brick (silicon carbide-mullite brick) is composed of a skeleton of special-grade bauxite clinker with Al2O3 higher than 80%, and a matrix made of silicon carbide, aluminum oxide, and silicon oxide. Corundum-magnesia alumina spinel castable, referred to as castable, is a kind of high-alumina refractory material, which is usually used for lining the bottom and wall of the converter refining ladle, and can significantly improve the service life of the ladle, which is more than twice the service life of magnesia carbon brick and magnesia alumina brick. Corundum-magnesia alumina spinel castable is mainly composed of special-grade bauxite or corundum, magnesium oxide, and silicon powder as main raw materials, and calcium aluminate cement as binder, and the main crystal phase is corundum and magnesia alumina spinel. High-voltage porcelain is waste material generated during the production process of high-voltage porcelain due to imperfect process or unqualified detection, and waste material generated during use due to performance detection damage or natural damage, such as high-voltage porcelain insulator, support, and sleeve.

[0034] The preparation method of the recycled aggregate includes the following steps: S1, selecting waste refractory materials; impurities in the waste refractory materials are removed by knocking, shoveling, and peeling off during the selection process; three kinds of waste refractory materials, silicon-mullite brick, corundum-magnesia alumina spinel castable, and high-voltage porcelain, are selected to prepare recycled aggregates, and the three kinds of high-alumina solid waste are first broken into small pieces with a size range of 50-100 mm before preparation; S2, the waste refractory materials are crushed by a jaw crusher, and the particle size of the feed is controlled to be ≤100 mm, and the particle size of the discharge is controlled to be ≤40 mm; the discharge port diameter of the jaw crusher is 65-75 mm, and the frequency of the moving jaw is 80-120 times / min; S3, the waste refractory materials crushed in S2 are crushed by an impact crusher, and the particle size of the discharge is controlled to be ≤20 mm; the impact crusher adopts a double-layer plate hammer spacing design, the first layer of plate hammer spacing is 35 mm, and the second layer of plate hammer spacing is 25 mm; the water absorption rate of the 10-20 mm particle size prepared by the impact crusher is 3.5-4%, and the water absorption rate of the 5-10 mm particle size is 4-4.5%.

[0035] S4, the waste refractory materials crushed in S3 are crushed by a cone crusher, and the particle size of the discharge is controlled to be ≤9.5 mm; the inclination angle of the circular vibrating screen is 20-24°, and the amplitude is 3-4.5 mm. The water absorption rate of the 5-10 mm particle size prepared by the cone crusher is 4-4.5%.

[0036] During the crushing process, a bag dust collector is used to control the content of particles below 0.075 mm to be ≤1.5%, which meets the requirements of the aggregate specification for highway engineering.

[0037] S5, screening to obtain different particle size gradation of recycled aggregate.

[0038] In the preparation method, the waste refractory material is crushed by three-stage crushing, jaw crusher, impact crusher and cone crusher in sequence, and the total energy consumption of three-stage crushing is less than or equal to 8 kWh / t, which is reduced by more than 20% compared with the traditional process. The application discloses recycled aggregate based on waste refractory material and a preparation method thereof, and the micro-differential abrasion structure is formed through three-stage crushing and screening process parameter collaborative optimization and the differential abrasion effect of corundum-mullite of the recycled aggregate, so that the material solves the problems of resource waste and anti-skid attenuation in the traditional process, is suitable for special sections of expressways, and has the advantages of resource recycling efficiency, long anti-skid service life and the like.

[0039] The recycled aggregate obtained from the three kinds of waste refractory materials has a density of 2.5-3.2 g / cm 3 , and a water absorption of less than 3%. According to the gradation requirement of the high anti-skid surface layer, the three kinds of aggregate are screened according to the target gradation, and table 1 shows the grading requirement of the recycled aggregate and the grading results.

[0040] Table 1: Grading requirement and results of recycled aggregate

[0041] The chemical composition of the recycled aggregate is usually tested by an X-ray fluorescence spectrometer (XRF), and the elements contained in the recycled aggregate are quantitatively analyzed. Table 2 shows the XRF test results of the recycled aggregate.

[0042] Table 2: Percentage content of chemical components of recycled aggregate

[0043] It can be seen from the analysis that the alumina content of the castable, silicon-mullite brick and high-voltage porcelain recycled aggregate is high, which is 84.48%, 64.48% and 46.83% respectively, indicating that the main wear-resistant component of the three kinds of recycled aggregate is Al2O3. Among them, the high-voltage porcelain and silicon-mullite brick contain 42.74% and 27.32% of SiO2 respectively, indicating that the wear-resistant components of the two kinds of aggregate also include SiO2. At the same time, the XRD test is carried out on the recycled aggregate. According to the XRF results of the recycled aggregate, the main chemical elements of the silicon-mullite brick, castable and high-voltage porcelain recycled aggregate are aluminum. By comparing the XRD images of the three kinds of recycled aggregate, the relative content of each phase of the three kinds of high-alumina aggregate is quantitatively analyzed by the Rietveld method, as shown in Figure 1 . In the selection of recycled aggregate, by adjusting the content ratio of corundum to mullite in the recycled aggregate (2:1-3:1), a micro-differential abrasion structure is formed, so that the surface roughness Ra after abrasion is greater than or equal to 3.0 μm.

[0044] And combined with the mineral composition, it can be seen that the content of corundum in the castable and high-voltage porcelain is more than 60%, and the main mineral phases of the silicon-mullite brick include corundum, mullite and silicon carbide. The high corundum content of the three kinds of recycled aggregates is the main source of their wear resistance, which is also the most significant feature that distinguishes them from the existing aggregate basalt or steel slag aggregate. The recycled aggregate of the application utilizes the hardness difference (2-3 levels) of corundum-mullite minerals to continuously regenerate the micro-roughness through the "differential polishing" mechanism, and the texture index is increased by at least 34.6% after abrasion.

[0045] Test Example 1 This embodiment uses the preparation method of the recycled aggregate of Example 1, and uses different moving jaw working frequencies in step S2 to test the damage rate and production capacity of the recycled aggregate. The test results are shown in Table 1. Figure 2 , Figure 3 According to the results, it can be seen that the damage rate of the 60mm discharge port is low, but the efficiency is also relatively low, so the discharge port diameter of the jaw crusher is selected to be 65-75mm, and the moving jaw frequency is 80-120 times / min.

[0046] Test Example 2 This embodiment is used to test the crushing value, Los Angeles abrasion value and polishing value of the three kinds of recycled aggregates prepared in Example 1. The crushing value is used to evaluate the crushing resistance of the aggregate under load, which is the ratio of the aggregate mass passing through a 2.36mm sieve to the mass of the sample before the test. The Los Angeles abrasion value (LAA) is obtained according to the test specification "Highway Engineering Aggregate Test Specification" (JTGE42-2005); the polishing value is an important indicator for evaluating the slip resistance of the aggregate, which is tested by a polishing instrument and a pendulum friction coefficient instrument. The test results are shown in Table 3.

[0047] Table 3 Test results of the crushing value, Los Angeles abrasion value and polishing value of the recycled aggregate

[0048] Through comparative analysis of the physical and mechanical properties of the three kinds of recycled aggregates, the PSV of the three kinds of aggregates is more than 55, the Los Angeles abrasion value is ≤20%, and the crushing value is ≤15%, which meets the specification requirements of HFST aggregate.

[0049] Test Example 3 To test the continuous impact and friction of the tire on the recycled aggregate, which causes the morphology of the aggregate to change, the Los Angeles abrasion test is used to simulate the stress condition of the recycled aggregate. According to the “Highway Engineering Aggregate Test Procedures” (JTG 42-2005), the morphology index change of the recycled aggregate in each cycle is observed. In this test, the Los Angeles abrasion test is improved. In the process of the abrasion test, the steel ball is no longer added. The particle size of the recycled aggregate is selected to be 4.75-9.5 mm. Each group of recycled aggregate is abraded for 3000 times. Each 500 times is a cycle, and there are six cycles. The AIMS II is used to test the morphology characteristics of the aggregate before and after the Los Angeles abrasion. The index of the recycled aggregate, such as the edge, the shape Form 2D , the texture, the sphericity, F:E , of each 50 recycled aggregates in each abrasion cycle is obtained. In order to compare, the three recycled aggregates in the above are compared with the existing aggregate. The aggregate used for comparison is the 88# calcined bauxite aggregate commonly used in HFST, the natural wear-resistant aggregate basalt, and the waste aggregate steel slag commonly used in anti-skid pavement at present. Among them, the AIMS divides the morphology index into four grades, i.e. low, medium, high, and extremely high, according to the size of each index. The value range and division standard of each index are shown in Figure 4 .

[0050] (1) Influence of aggregate angularity on wear resistance During the abrasion process, the angularity of the aggregate will be abraded first by the abrasion tester, which will cause the angularity to decrease. The change trend of the average angularity of the aggregate with the number of abrasions and the change rate before and after the abrasion are shown in Figure 5 and Figure 6 . The initial angularity of the six kinds of aggregates is ranked as: silica brick > steel slag > castable > high-voltage porcelain > calcined bauxite > basalt. In the first 2000 abrasions, the angularity of the aggregate decreases the fastest. After 2000 times, the angularity of the aggregate decreases slowly. The angularity of part of the aggregate tends to be stable. After 3000 abrasions, the final value is reached. The angularity decreases as a whole. During the abrasion process, the angularity will fluctuate up and down, which is due to the collision of the aggregate with the inner wall of the abrasion tester and the temporary new angularity generated by the breaking of the aggregate. After the abrasion test, the angularity of the six kinds of aggregates decreases to different degrees, with a decrease range of 21.4%-35.4%. Among them, the angularity of the steel slag, the castable, and the silica brick decreases the most, all of which are more than 30%. The average angularity of the steel slag aggregate decreases by 35.37%, which has the largest decrease. However, after 3000 times of Los Angeles abrasion test, the angularity of the silica brick is still better than that of the other five kinds of aggregates, followed by the high-voltage porcelain.

[0051] In general, the angularity of various aggregates decreases after abrasion. However, due to the difference in mineral composition of aggregates and the difference in the structure of aggregates, the reduction of angularity of different types of aggregates is different. Therefore, for the pavement with high anti-skid requirements, aggregates with high angularity and more wear-resistant components should be preferred.

[0052] (2) Effect of Form 2D of aggregates on abrasion resistance After abrasion, the passing percentage curves of aggregates move to the left, indicating that the Form 2D of the six aggregates decreases significantly after abrasion. The change trend of the average Form 2D of aggregates with the number of abrasion and the change rate before and after abrasion are shown in Figure 7 and Figure 8 It can be seen from Figure 7 that the decrease of the average Form 2D of the six aggregates mainly concentrates in the first 2000 times of abrasion, and the sphericity value of the aggregate basically does not change after 2000 times of abrasion, and reaches the final value. Among them, the decrease of Form 2D of high-voltage porcelain mainly concentrates in the first 500 times, and the two-dimensional shape of the aggregate basically does not change after 500 times of abrasion, indicating that its mechanical properties are good, and the influence of abrasion on the shape is small, and the fluctuation range of the castable is the largest. According to Figure 8 , the Form 2D index of the aggregate after abrasion is in the order of high-voltage porcelain > silica brick > basalt > calcined bauxite > steel slag > castable, and the final value of most aggregates is between 5~7. The decrease range of Form 2D of the six aggregates is between 17.3%~29.2%; the largest is the castable, which is 29.2%, followed by steel slag and silica brick, which are 29.2% and 24.0% respectively; the largest decrease range of castable is due to its low matrix strength and loose structure, which leads to the abrasion of the matrix first, resulting in a large decrease of Form 2D. Although the abrasion resistance of steel slag is good, the surface of the aggregate will be gradually rounded in the later stage of abrasion, resulting in a large decrease of Form 2D index.

[0053] Because the structure of high-alumina recycled wear-resistant aggregate is different from that of traditional aggregate, although the LAA value of silica brick is high, its angularity and Form 2D are higher among the six aggregates. Therefore, when evaluating the abrasion resistance of aggregate, the LAA value cannot directly reflect the good or bad of the abrasion resistance, and the angularity of the aggregate should be considered, and the Form 2D index of the aggregate should also be considered, which greatly affects the abrasion performance of the aggregate in the later stage.

[0054] (3) Effect of microtexture of aggregate on abrasion resistance The texture of aggregate changes differently from the angularity of aggregate. The surface texture of some aggregates changes less after abrasion, and for some aggregates, it even increases slightly. The change trend of the average texture value of the aggregate with the number of abrasion and the change rate before and after abrasion are shown in Figure 9 andFigure 10 As shown in Figure 9 It can be seen that, unlike the aggregate angularity and Form 2D variation trend, the texture of the aggregate changes less after the Los Angeles abrasion test, indicating that it has less effect on the texture of the aggregate. As shown in Figure 10 After the Los Angeles abrasion test, the texture of the silicon carbide brick and high-voltage porcelain aggregate increased to different degrees, by 34.6% and 49.5% respectively before abrasion. The slight increase in texture during abrasion may be due to the fact that some aggregate has new fracture surfaces during the abrasion process. Due to the high needle-like content of high-voltage porcelain and the smoothness of its initial fracture surface, its texture value is the lowest among the six aggregates at the initial stage of abrasion, and although it increases greatly at the later stage of abrasion, its final value is still the lowest, only 27% of the average texture of silicon carbide brick. The initial texture of silicon carbide brick is at a medium level among the six aggregates, but after abrasion, its average texture value is only second to basalt, which is 529. This is mainly due to the existence of the matrix and aggregate structure of silicon carbide brick, and the high roughness of both, which leads to a significant increase in the texture of the aggregate after 3000 abrasions. The aggregate with the most texture decrease after abrasion is basalt and castable, which decreased by 22.9% and 32.9% respectively.

[0055] (4) Effect of aggregate sphericity on abrasion resistance The sphericity percentage curve of the aggregate after abrasion moves to the right to varying degrees, indicating that the sphericity of the six aggregates has increased to varying degrees. The change trend of the average sphericity of the aggregate with the number of abrasions and the change rate before and after abrasion are shown in Figure 11 and Figure 12 From Figure 11 and Figure 12 , it can be seen that the sphericity of the aggregate after abrasion has increased to varying degrees. The slight increase in sphericity is mainly due to the decrease in the angularity of coarse aggregate, and the increase in sphericity is also related to the flat or elongated particles in the aggregate. Flat or elongated particles are more likely to break than round particles, resulting in a larger increase in sphericity. The final sphericity of calcined bauxite and high-voltage porcelain is the lowest, with a change rate of 4% and 2.8% respectively, which also reflects the good compression performance of the two aggregates, and the shape is not easy to change during long-term abrasion. The sphericity change rate of silicon carbide brick and castable is the largest, increasing by 13.8% and 12.9% respectively. The average sphericity value of steel slag, silicon carbide brick and castable is the highest after abrasion, all above 0.7. The flatness and elongation of these aggregates are relatively large, making the aggregate more likely to break. Therefore, it is recommended to use coarse aggregate with less flat or elongated particles for heavy traffic roads.

[0056] (5) Effect of aggregate flatness and elongation ratio (F&E) on abrasion resistance Most aggregates were distributed within an F:E ratio of 1:4, while a small number were distributed within an F:E ratio of 1:6. This means that the proportion of particles with an F:E ratio between 1:4 and 1:6 generated by the wear test was relatively small. The trends in the average F:E ratio of the aggregates with the number of wear cycles and the rate of change before and after wear are shown below. Figure 13 and Figure 14 As shown. Figure 13 and Figure 14 As shown, among the six aggregates, basalt experienced the largest decrease in F:E ratio at 22.4%, which is related to its relatively high growth rate in sphericity (11.1%). The decreases in F:E ratio for calcined bauxite, silica-mullite bricks, and castables were concentrated between 16% and 19%. For high-voltage electrical porcelain, although its F:E ratio decreased less (8.3%), its initial and final F:E values ​​were the highest among the six aggregates. This is because the high-voltage electrical porcelain aggregate itself has a high content of needle-like and flaky particles after crushing, resulting in higher flatness and slenderness. However, due to its high material strength, the overall decrease in its F:E ratio was not significant.

[0057] Test Example 5 Hardness testing is a crucial parameter for evaluating material strength. Nanoscale hardness testing can measure the hardness of different phases of a material at the microscopic level. Nanoscale indentation hardness distribution maps of six aggregates were obtained. Calcined bauxite, silica-mullite brick, castables, and high-voltage electrical porcelain showed the highest hardness values, ranging from 0 to 54 GPa. Different hardness differences, exceeding 20 GPa, were observed on the surfaces of calcined bauxite, silica-mullite brick, and high-voltage electrical porcelain, primarily related to the corundum and mullite phases in these three aggregates. Although the castables exhibited a wider hardness range, no significant hardness differences formed on their surfaces, resulting in poorer microtexture after wear. Furthermore, the presence of a large matrix reduced the microtexture of the castables. Basalt and steel slag showed the lowest hardness values, ranging from 0 to 14 GPa. No significant hardness differences were observed on the surfaces of these aggregates, and their microtexture after wear was inferior to that of the four high-alumina waste aggregates.

[0058] Example 2 This embodiment provides an anti-skid and wear-resistant pavement, including a base layer, on which an adhesive layer and a wear layer are sequentially disposed. The wear layer is composed of recycled aggregate based on waste refractory materials as described in Embodiment 1 above.

[0059] Recycled aggregates from waste refractory materials can be used for anti-skid and wear-resistant pavements, realizing the resource utilization of waste materials and improving the anti-skid performance of pavements, disposing of industrial solid waste, reducing mining operations, and lowering carbon emissions.

[0060] The bonding layer is selected from E41 epoxy resin adhesive and curing agent. The epoxy resin adhesive and the curing agent are mixed at a ratio of 1:1.2, and then fully stirred to form the adhesive. The viscosity of the adhesive is 0.7-2.5 Pa·s, the tensile strength (25℃, 7d) is 17-35 MPa, the elongation at break (25℃, 7d) is 30-70%, and the elastic modulus (25℃, 7d) is ≤900 MPa.

[0061] The aggregates are selected from the six aggregates in Test Example 3, i.e., silica brick, castable, high-voltage porcelain, steel slag, calcined bauxite, and basalt. The aggregates are used as the wearing layer to prepare HFST (High Friction Surface Treatment) samples. Two groups of HFST samples are prepared for each aggregate for parallel testing. The specific preparation process of the HFST samples is as follows: a. Preparation of the concrete base. The size of the concrete base is 50×50×5 cm 3 After the base is formed, an angle grinder is used to polish the surface of the concrete base to ensure that the surface is flat and free of protrusions.

[0062] b. The six aggregates and the epoxy resin and curing agent are weighed respectively. The amount of aggregate used in the surface layer of each group of HFST samples is 2.13-2.30 kg, and the amount of epoxy resin and curing agent is 0.19-0.21 kg. A stirrer is used to mix the adhesive for about 3 min.

[0063] c. Bonding process of the aggregate. The epoxy resin adhesive is applied using a notched chloroprene rubber scraper, and a wet film thickness gauge is used to control the thickness of the adhesive to be 1.016-1.27 mm. The aggregate should be evenly spread on the epoxy resin bonding layer, and the aggregate must cover the adhesive to ensure that there are no "wet" spots on the surface of the HFST.

[0064] d. After the epoxy resin adhesive is completely cured, the excess aggregate on the surface of the HFST is removed to obtain the HFST sample, as shown in Figure 15 .

[0065] The three-wheel accelerated pavement tester (TWPD) simulates the long-term skid resistance attenuation process of the HFST sample. The self-weight of the TWPD is 100 kg, and the test wheel is made of rubber. In order to ensure that the wear area of the HFST sample surface is consistent with the rotating measurement area of the DFT turntable, the wear track is a circular ring with a diameter of 284 mm. The contact area between the tire and the HFST sample is 11.55 cm2, the tire pressure is set to 0.7 MPa, the loading weight of the TWPD is 243 kg, and the main shaft speed is 25 r / min. One wear cycle is 10,000 times, and a group of samples is worn for 14 cycles, with a total of 140,000 times. According to the requirements of the ASTM E1911-09 specification, the JDF-08 dynamic friction coefficient tester is used to test the dynamic friction coefficient of the HFST surface at 40 km / h and 60 km / h. μ , are sequentially represented as μ 40 , μ 60 . After each wear cycle, the crushed aggregate on the HFST surface is first cleaned, and the AMES pavement texture laser scanner is used to obtain the three-dimensional topography of the HFST. According to the elevation measurement value of each cycle after wear, the average profile depth (MPD) of the scanned area is calculated.

[0066] The attenuation process of the dynamic friction coefficient is shown in Figure 16 , and the final value of the DF of the HFST is shown in Table 4. The dynamic friction coefficient of most aggregates reaches the final value after the 10th cycle, and in this experiment, the wear test cycle is adjusted to 14 to distinguish the skid resistance of high-wear-resistant aggregates.

[0067] Table 4 Final value of dynamic friction coefficient of HFST of different aggregates

[0068] As can be seen from the figure, the attenuation process of the HFST mainly includes three stages: the accelerated attenuation stage (0~50,000 times), the gentle attenuation stage (5~10,000 times), and the stable stage (10~14,000 times). The final DF value of each aggregate is ranked as: calcined bauxite > silica brick > high-voltage porcelain > basalt > castable > steel slag. Among them, the skid resistance of the silica brick is 90% of that of the calcined bauxite, which is significantly higher than that of other high-alumina wear-resistant recycled aggregates, and the final value of μ 40 is 1.4 times that of basalt and castable. This is related to the mineral composition and texture of the silica brick. The content of Al2O3 and SiC in the silica brick is very high, and both of these components contribute to the wear resistance of the aggregate. The HFST using basalt aggregate has good skid resistance in the first 5 cycles, but its attenuation rate is significantly higher than that of castable and high-voltage porcelain. In the first five cycles, the skid resistance of basalt is higher than that of castable and high-voltage porcelain, while in the later wear period, the μ40 and μ 60 The difference is continuously reduced, and at the end of the abrasion, the anti-skid resistance of the three aggregates is ranked as high-voltage porcelain > basalt > castable. As a replacement aggregate of HFST, the castable and high-voltage porcelain can reach the anti-skid level comparable to basalt and can be applied to road sections and longitudinal slopes with less demand for anti-skid resistance. The anti-skid resistance of steel slag in HFST is only 48% of that of calcined bauxite, and the long-term anti-skid performance is poor. In the 5-10 period of the gentle decay stage, the dynamic friction coefficient of the steel slag decreases faster than that of the other five aggregates. After abrasion, the aggregate presents obvious luster, and the anti-skid performance cannot meet the anti-skid standard of the HFST pavement.

[0069] The loss rate and decay rate are used as the evaluation indexes of the anti-skid performance decay. The former is the loss rate of the dynamic friction coefficient and MPD after 10 periods of abrasion, which is represented as Δμ / μ 初始值 and ΔMPD / MPD 初始值 . The latter is the decay rate of the dynamic friction coefficient and MPD of the HFST after the three-wheel abrasion test, which is represented as Δμ / 10 periods and ΔMPD / 10 periods. The loss rate and decay rate of μ 40 at the simulation speed of 40 km / h are shown in Table 5.

[0070] Table 5 Loss rate and decay rate of μ 40

[0071] As can be seen from the table, the loss rate and decay rate of μ 40 of calcined bauxite and silicon-mullite brick, castable, and high-voltage porcelain are low, which is related to the high alumina content of the aggregate. The presence of alumina can slow down the decay of the anti-skid resistance of the aggregate, so that the aggregate can maintain a stable dynamic friction coefficient in the later abrasion period. Among the six aggregates, the loss rate and decay rate of μ 40 of basalt and steel slag aggregate are the highest, indicating that the anti-skid resistance of the two aggregates decreases greatly in the later abrasion period, and the long-term anti-skid performance is poorer than that of high-alumina aggregate. Therefore, the anti-skid performance of the pavement using the recycled aggregate of the present application is improved by more than 40%, the service life is prolonged to 1.5 times of the traditional surface layer, and the decay rate of the dynamic friction coefficient is greatly reduced.

[0072] The average section depth decay law is analyzed, and the MPD decay process of the six HFSTs is shown in Table 6. Figure 17

[0073] Table 6 Loss rate and decay rate of MPD

[0074] ​​According to the above data, it can be seen that there is a certain difference in the initial value of MPD of the six HFSTs, which is mainly due to the slight difference in the particle size of the aggregate. Before the test, the crushed aggregate has been sieved for many times to minimize the test error caused by the difference in particle size. In terms of macrostructure control, by adjusting the particle size and grading of the aggregate, the average section depth (MPD) is 1.2-1.5mm, which improves the high-speed skid resistance by 30% compared with the traditional process. The MPD of the six HFSTs rapidly decays within 1~5 cycles. In the 5~10 cycle gentle decay stage, the MPD value of the aggregate is relatively stable, but there are different degrees of fluctuations, which is due to the fact that in the process of abrasion, the relatively weak part of the aggregate is crushed and falls off, resulting in a height difference with the relatively hard part of the aggregate, thus causing the fluctuation of the MPD value. After 10 cycles, the MPD of the HFST basically no longer changes, entering the stable stage.

[0075] The MPD loss rate of calcined bauxite and silica brick is the lowest, which is consistent with their excellent skid resistance. The MPD loss rate and decay rate of basalt, high-voltage porcelain and steel slag are higher, indicating that their macrotexture decays faster, and their long-term skid resistance is poorer than other aggregates. The MPD decay rate of high-voltage porcelain is related to its higher needle-like content.

[0076] The wheel travel trajectory and local track of the six aggregate HFST specimens after 140,000 abrasions were tested, and the three-dimensional structure of the road surface was reconstructed by the AMES road texture laser scanner to reflect the more realistic texture of the road surface. Figure 18 The three-dimensional topography and planar graph of different HFSTs after three-wheel abrasion test are shown in the figures, and different colors represent different heights. The green raised area represents the aggregate on the surface of the HFST, and the blue area is the epoxy resin binder. The HFST has rich macrotexture, and the average MPD before abrasion is 1.097~1.731mm. Compared with the non-abrasion state, after 140,000 abrasions, the MPD of the HFST decreases to 0.347~1.003mm. During the abrasion process, the macrotexture becomes smoother, and the dense peaks gradually disappear, indicating that the aggregate is abraded and compacted, and the proportion of protruding aggregate decreases significantly.

[0077] Road surface skid resistance is related not only to the macroscopic texture of aggregates but also closely to their microscopic texture; both textures jointly influence road surface skid resistance. Microscopic texture is generated by the surface roughness of aggregate particles, and its magnitude depends on the initial surface roughness of the aggregate and its ability to retain this roughness after polishing. SEM images of six aggregates before and after wear at the same scale show that the surface texture of the aggregates tends to be smoother after wear. Steel slag and high-voltage porcelain have the smoothest surfaces, followed by castables and basalt. Calcined bauxite and silica-molybdenum bricks have the most similar surfaces, with a relatively dense structure and high roughness. To more clearly characterize and quantify the surface roughness of the aggregates, a 3D laser microscope was used to test the aggregate roughness before and after wear. (Surface roughness of six aggregates before and after wear) Sa The results are as follows Figure 19 As shown.

[0078] As shown in the figure, the initial surface roughness of the six aggregates... Sa The order of size is: silica-mullite brick > basalt > steel slag > castable > calcined bauxite > high-voltage electrical porcelain. The surface texture of the aggregates became smoother after abrasion. The surface roughness of the six aggregates decreased by 12.9%, 68.9%, 91.01%, 47.1%, 65.5%, and 2.3% respectively after abrasion. (Surface roughness after abrasion) Sa Sa The order of size is: silica-mullite brick > calcined bauxite > high-voltage electrical porcelain > basalt > castable > steel slag. This shows that the micro-texture after wear and the ability of the aggregate to maintain its micro-texture are directly proportional to its anti-slip performance. When evaluating the anti-slip level of aggregates, their micro-texture is indispensable. After wear, calcined bauxite and silica-mullite bricks still exhibit significant protrusions on their surfaces, with surface roughness reaching 69.58 μm and 100.32 μm, respectively, which are 5.8 to 8.3 times that of steel slag. This is consistent with the SEM test results, indicating that both aggregates can maintain good micro-texture after long-term wear tests. Utilizing the hardness difference between corundum (hardness 8.5-9) and mullite (hardness 6-7) in waste refractory materials, a continuous micro-rough structure is formed through differential wear effect. After 140,000 wear cycles, the surface roughness (Ra) is ≥3.0 μm.

[0079] The above tests verified the feasibility of applying the recycled aggregate of the present invention to HFST pavement. At the end of the wear period, the dynamic friction coefficient μ of the silica-mullite brick was 98% of that of calcined bauxite, which proved that the silica-mullite brick can provide a skid resistance level comparable to that of calcined bauxite. The skid resistance of the other two types of high-alumina recycled wear-resistant aggregate castables and high-voltage electrical porcelain were all above 0.57. The later skid resistance decay process was relatively stable, and it can be used in road sections with lower skid resistance requirements according to the actual skid resistance requirements of the road.

[0080] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A recycled aggregate based on waste refractory materials, characterized in that, The recycled aggregate is prepared from waste refractory materials. The recycled aggregate has a particle size ≤ 9.5 mm, angularity ≥ 3200 AIMS units, Form2D index ≥ 7.5, sphericity 0.6~0.7, and flatness to elongation ratio ≥ 2.

5.

2. The recycled aggregate based on waste refractory materials according to claim 1, characterized in that, The waste refractory materials include at least one of silica-mullite bricks, corundum-magnesium-aluminum spinel castables, and high-voltage electrical porcelain.

3. The recycled aggregate based on waste refractory materials according to claim 2, characterized in that, By mass percentage, the silicon-mullite brick contains more than 60% Al2O3 and more than 20% SiO2; the corundum-magnesium-aluminum spinel castable contains more than 70% Al2O3 and more than 8% MgO; and the high-voltage electrical porcelain contains more than 45% Al2O3 and more than 40% SiO2.

4. The recycled aggregate based on waste refractory materials according to claim 2, characterized in that, The phases of the silicon-mullite brick include corundum, mullite, and silicon carbide, wherein the corundum content is greater than 45%; the phases of the corundum-magnesium aluminum spinel castable include corundum and magnesium aluminum spinel, wherein the corundum content is greater than 60%; the phases of the high-voltage electrical porcelain include corundum, mullite, and silicon carbide, wherein the corundum content is greater than 60%.

5. A recycled aggregate based on waste refractory materials according to any one of claims 1-4, characterized in that, The recycled aggregate has a polished value PSV ≥ 55 BPN, a Los Angeles abrasion value ≤ 20%, and a crushing value ≤ 15%.

6. A method for preparing recycled aggregate based on waste refractory materials as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Select the waste refractory materials; S2. The waste refractory material is crushed using a jaw crusher, with the feed particle size ≤100mm and the discharge particle size ≤40mm. S3. The waste refractory material after S2 crushing is crushed using an impact crusher to control the discharge particle size to ≤20mm. S4. The waste refractory material after S3 crushing is crushed using a cone crusher to control the discharge particle size to ≤9.5mm; S5. Screening is performed to obtain the recycled aggregate with different particle size distributions.

7. The method for preparing recycled aggregates based on waste refractory materials according to claim 6, characterized in that, The jaw crusher has a discharge diameter of 65~75mm and a moving jaw frequency of 80~120 times / min.

8. A method for preparing recycled aggregates based on waste refractory materials according to claim 6, characterized in that, The impact crusher adopts a double-layer hammer spacing design. The first layer of hammers has a spacing of 30~40mm, and the second layer of hammers has a spacing of 20~30mm, which makes the needle and flaky content of the recycled aggregate ≤12% and the water absorption rate reduced to below 5%.

9. A method for preparing recycled aggregates based on waste refractory materials according to claim 6, characterized in that, The circular vibrating screen of the cone crusher has an inclination angle of 20~24° and an amplitude of 3~4.5mm.

10. A skid-resistant and wear-resistant pavement, comprising a base layer, wherein an adhesive layer and a wear layer are sequentially disposed on the base layer, characterized in that, The wear layer is composed of recycled aggregate based on waste refractory material as described in any one of claims 1-5 or recycled aggregate prepared by a method for preparing recycled aggregate based on waste refractory material as described in any one of claims 6-9.

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