Steel slag cold-mixed and cold-laid wearing layer material as well as design method and application thereof

Abstract

The invention provides a steel slag cold-mixed and cold-laid wearing layer material and a design method and application thereof.The steel slag cold-mixed and cold-laid wearing layer material comprises an asphalt mixture with the grading type being MS-3, the asphalt mixture comprises steel slag, aggregate, emulsified asphalt, filler and externally-doped water, in the asphalt mixture, the 9.5 mm screening passing rate is 100%, and the aggregate is a steel slag aggregate. The passing rate of 4.75 mm screening is 70%-90%, the passing rate of 2.36 mm screening is 45%-70%, the passing rate of 0.075 mm screening is 6%-12%, the dosage of the externally doped water is 3%-6% of the total mass of the steel slag and the aggregate, and the asphalt-aggregate ratio of the asphalt mixture is 6%-8%; the steel slag cold-mixed and cold-laid wearing layer with excellent performance is prepared by adopting the steel slag instead of natural aggregate, so that the problem of consumption of industrial solid waste steel slag is solved, and meanwhile, a large quantity of requirements on preventive maintenance of the asphalt pavement are met.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering, and in particular to a steel slag cold-mixed and cold-laid wearing layer material, a design method thereof, and an application thereof. Background Art

[0002] In recent years, my country has achieved historic success in highway construction and development, with its highway infrastructure network continuously improving. By the end of 2023, my country's total highway mileage reached 5.441 million kilometers, an increase of 1.211 million kilometers over the past decade. The mileage of expressways in operation reached 184,000 kilometers, firmly ranking first in the world. The vast majority of newly built highways are paved with asphalt. Its advantages, such as driving comfort and low noise, have earned it widespread recognition among road builders and users. However, under the combined effects of vehicle loads and the natural environment, asphalt pavements are susceptible to reduced skid resistance, even water damage such as loosening, spalling, and potholes, as well as surface cracks caused by horizontal shear forces. These cracks provide pathways for water to enter the pavement, accelerating the development of pavement damage. As highways continue to age, large-scale maintenance of asphalt pavements has become a top priority for the current highway industry. Consequently, the core of highway management has shifted from construction to maintenance. In 2015, the maintained mileage of highways in my country was 4.4656 million kilometers; by 2022, this figure had increased to 5.3501 million kilometers.

[0003] Among the many maintenance technologies, ultra-thin wear layers have been widely used due to their excellent economic performance. Not only that, they can also adapt to diverse environmental requirements and meet the current needs of highway construction and its use in my country. As a preventive maintenance measure, this technology can not only effectively repair and treat the surface of asphalt roads, but also significantly improve the service performance of roads by forming a wear-resistant and anti-skid surface layer. The ultra-thin wear layers currently used for road maintenance are mostly prepared from natural aggregates, which are non-renewable resources. Excessive mining can easily lead to depletion and ecological damage, and the mining and transportation costs are high. In terms of performance, their anti-skid and wear resistance, water stability, and resistance to rutting and cracking are all limited, and they are prone to diseases under heavy loads, rainy and low temperature environments. In addition, their grading adjustment flexibility is low, making it difficult to adapt to the needs of ultra-thin wear layers, resulting in short maintenance cycles and high long-term maintenance costs.

[0004] Therefore, there is an urgent need for a steel slag cold-mixed cold-laid wearing layer material and its design method and application to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a steel slag cold-mixed and cold-laid wearing layer material and its design method and application, so as to solve the technical problems of ultra-thin wearing layer materials prepared from existing natural aggregates, such as the destruction of ecology by natural aggregate mining and high cost, poor anti-skid and wear resistance and water stability, easy generation of rutting cracks, difficulty in grading adjustment to adapt to ultra-thin layer requirements, short maintenance cycle and high cost.

[0006] In order to solve the above technical problems, the present invention first provides a steel slag cold mix cold laying wearing course material, comprising an asphalt mixture of MS-3 gradation type, wherein the raw materials of the asphalt mixture include steel slag, aggregate, emulsified asphalt, filler and external water; Among them, in asphalt mixture: the 9.5mm screening pass rate is 100%, the 4.75mm screening pass rate is 70%~90%, the 2.36mm screening pass rate is 45%~70%, and the 0.075mm screening pass rate is 6%~12%; the amount of external water used is 3%~6% of the total mass of steel slag and aggregate; the oil-stone ratio of the asphalt mixture is 6%~8%.

[0007] Preferably, the synthetic gradation of the asphalt mixture is as follows: the 9.5mm screening pass rate is 100%, the 7.2mm screening pass rate is 94%, the 4.75mm screening pass rate is 84%, the 2.36mm screening pass rate is 47.5%, the 1.18mm screening pass rate is 39%, the 0.6mm screening pass rate is 26.5%, the 0.3mm screening pass rate is 18.5%, the 0.15mm screening pass rate is 12.5%, and the 0.075mm screening pass rate is 8%.

[0008] Preferably, the particle size of the steel slag is 2.36-9.5 mm.

[0009] Preferably, the asphalt mixture includes coarse material with a particle size of 2.36-9.5 mm, and the amount of steel slag accounts for 30%-90% of the volume ratio of the coarse material.

[0010] Preferably, the filler comprises mineral powder, and the particle size of the mineral powder is ≤0.075 mm.

[0011] Preferably, the aggregate comprises one or more of limestone, basalt, diabase and tuff.

[0012] Accordingly, the present invention further provides a design method for a cold-mixed and cold-laid steel slag wearing layer material as described above, the design method comprising: S10, select the type of raw materials for asphalt mixture according to project requirements and design the gradation type; S20, determining the amount of water added to the asphalt mixture based on the mixing test; S30, determine the asphalt-to-stone ratio of the asphalt mixture based on the wet wheel abrasion test and the load wheel sand adhesion test; S40: Prepare the steel slag cold mix and cold lay wearing layer material according to the raw material type, gradation type, external water content and oil-stone ratio and conduct performance index testing; S50, judging whether the performance indicators of the steel slag cold-mixed cold-laid wearing layer material meet the requirements. If a performance indicator does not meet the requirements, repeating steps S10 to S40 until the requirements are met, and finally completing the design of the steel slag cold-mixed cold-laid wearing layer material.

[0013] Preferably, in step S10: the gradation type of the asphalt mixture is MS-3, and the raw materials of the asphalt mixture include steel slag, aggregate, emulsified asphalt, filler and external water; in step S20: the amount of external water is 3% to 6% of the total mass of the steel slag and aggregate; in step S30: the oil-stone ratio of the asphalt mixture is 6% to 8%.

[0014] Preferably, in step S40: a rutting test is used to evaluate the high temperature performance of the cold-mixed and cold-laid steel slag wearing layer material, a 6-day immersion wet wheel abrasion test is used to evaluate the water damage resistance of the cold-mixed and cold-laid steel slag wearing layer material, a pendulum apparatus method is used to evaluate the anti-skid performance of the cold-mixed and cold-laid steel slag wearing layer material, and a slurry mixture rutting deformation test is used to evaluate the anti-rutting performance of the cold-mixed and cold-laid steel slag wearing layer material.

[0015] Accordingly, the present invention also provides an application of a cold-mixed cold-laid steel slag wearing layer material as described above and / or a design method of a cold-mixed cold-laid steel slag wearing layer material as described above in pavement maintenance.

[0016] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides a steel slag cold mix cold paving wearing layer material and its design method and application, wherein the steel slag cold mix cold paving wearing layer material comprises an asphalt mixture of MS-3 gradation type, the raw materials of the asphalt mixture comprise steel slag, aggregate, emulsified asphalt, filler and external water, wherein, in the asphalt mixture: the 9.5mm sieve pass rate is 100%, the 4.75mm sieve pass rate is 70%~90%, the 2.36mm sieve pass rate is 45%~70%, the 0.075mm sieve pass rate is 6%~ The amount of external water is 3% to 6% of the total mass of steel slag and aggregate, and the oil-stone ratio of the asphalt mixture is 6% to 8%. The present invention prepares a steel slag cold-mixed and cold-laid wearing layer with excellent performance by scientifically designing the raw material ratio, gradation type, external water dosage and oil-stone ratio, and using steel slag instead of natural aggregate, which solves the consumption problem of industrial solid waste steel slag while meeting the large demand for preventive maintenance of asphalt pavement. Moreover, compared with ordinary ultra-thin wearing layers, the addition of steel slag can effectively improve the high-temperature stability, water stability, anti-skid and anti-rutting capabilities of the ultra-thin wearing layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A flow chart of a design method for a cold-mixed and cold-laid steel slag wearing layer material according to an embodiment of the present invention; Figure 2 This is a graph showing the oil-stone ratio of the cold-mixed and cold-laid steel slag wearing layer material provided in Example 1; Figure 3 Schematic diagram comparing the dynamic stability of the cold-mixed and cold-laid steel slag wearing layer material provided in Example 1 and the ultra-thin wearing layer with 0% steel slag content; Figure 4 Schematic diagram comparing wet wheel wear values ​​of the cold-mixed and cold-laid steel slag wearing layer material provided in Example 1 and the ultra-thin wearing layer with 0% steel slag content; Figure 5 Schematic diagram showing the swing value comparison between the cold-mixed and cold-laid steel slag wearing layer material provided in Example 1 and the ultra-thin wearing layer with 0% steel slag content; Figure 6 Schematic diagram comparing the unit width deformation rate of the cold-mixed and cold-laid steel slag wearing layer material provided in Example 1 and the ultra-thin wearing layer with 0% steel slag content; Figure 7 Schematic diagram comparing the rutting depth rate per unit thickness of the cold-mixed and cold-laid steel slag wearing layer material provided in Example 1 and the ultra-thin wearing layer with 0% steel slag content. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] In response to the technical problems existing in ultra-thin wear layer materials prepared from existing natural aggregates, the present invention proposes a design method and application for preparing a cold-mixed, cold-laid ultra-thin wear layer using steel slag. In the context of green, low-carbon, and circular development, based on the good physical and chemical properties of steel slag materials and the ease of construction of the cold-mixed, cold-laid process, it is proposed to use steel slag instead of natural aggregate to prepare a high-performance steel slag cold-mixed, cold-laid wear layer, which solves the problem of industrial solid waste steel slag consumption and meets the large demand for preventive maintenance of asphalt pavements. In addition, compared with ordinary ultra-thin wear layers, the addition of steel slag can effectively improve the high-temperature stability, water stability, anti-skid and anti-rutting capabilities of the ultra-thin wear layer.

[0020] At present, according to statistics, the cumulative reserves of various types of steel slag in my country have exceeded 2 billion tons, and the current annual output exceeds 100 million tons. However, the utilization rate of steel slag in my country is less than 30%, which has resulted in steel slag occupying a large amount of land resources for storage and has caused a series of problems such as water pollution and air dust pollution. How to achieve the recycling of steel slag has also become a research hotspot. In this regard, the applicant has found through research that steel slag has many advantages when used as a material for ultra-thin wearing layers of roads: First, steel slag has excellent physical and mechanical properties, and has better crushing value and abrasion resistance than natural aggregates. When used in ultra-thin wearing layers, it can improve anti-skid and anti-rutting capabilities; second, steel slag has better adhesion to asphalt than natural aggregates, and when used in ultra-thin wearing layers, it can improve water stability; third, although steel slag has a greater risk of volume expansion, the thickness of the ultra-thin wearing layer itself is small, which can effectively reduce this adverse effect; fourth, it can solve the problem of natural aggregate shortage in the highway maintenance industry while meeting the needs of highway maintenance.

[0021] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, the present invention provides a steel slag cold mix cold paving wearing course material, comprising an MS-3 gradation type asphalt mixture, wherein the raw materials of the asphalt mixture include steel slag, aggregate, emulsified asphalt, filler and external water; Among them, in asphalt mixture: the 9.5mm screening pass rate is 100%, the 4.75mm screening pass rate is 70%~90%, the 2.36mm screening pass rate is 45%~70%, and the 0.075mm screening pass rate is 6%~12%; the amount of external water used is 3%~6% of the total mass of steel slag and aggregate; the oil-stone ratio of the asphalt mixture is 6%~8%.

[0022] Specifically, the steel slag cold-mix cold-laid wearing course material uses an MS-3 asphalt mixture gradation, and its raw material composition and proportion design are scientifically considered. The 9.5mm screening pass rate is set to 100%, ensuring that the mixture particle size is within a reasonable range, laying the foundation for a uniform and stable structure. The 4.75mm screening pass rate is controlled at 70% to 90%, and the 2.36mm screening pass rate is 45% to 70%. This gradation allows coarse and fine aggregates to interlock, building a dense skeleton structure with high internal friction resistance, improving the material's resistance to deformation, and enhancing high-temperature stability and anti-rutting performance. The 0.075mm screening pass rate is 6% to 12%, ensuring that an appropriate amount of fine aggregate fills the pores, optimizing the density and surface smoothness of the mixture, while avoiding the problem of insufficient strength caused by excessive fine material.

[0023] Specifically, the amount of external water used is 3% to 6% of the total mass of steel slag and aggregate, which can effectively promote uniform demulsification of emulsified asphalt, optimize the workability of the mixture, facilitate construction at room temperature, and at the same time improve the compaction density and aggregate-asphalt interface bonding strength, and enhance the durability of the material; this amount can also compensate for water absorption and meet the wetting requirements of fine aggregate, reduce the lower limit of construction temperature, achieve energy conservation and emission reduction, and avoid risks such as segregation and insufficient strength caused by improper water amount.

[0024] Specifically, the oil-stone ratio of the asphalt mixture is controlled at 6% to 8%, which can ensure that the emulsified asphalt fully wraps the steel slag and aggregate to form a strong bonding structure, effectively improving the wear resistance, skid resistance and fatigue resistance of the mixture, and ensuring the long-term use quality of the road surface; it can also avoid the looseness and peeling problems caused by too low asphalt dosage, and the oil spillage and rutting phenomena caused by too high dosage, while taking into account the construction workability and economy to achieve the best balance between material performance and cost.

[0025] In one embodiment, the synthetic gradation of the asphalt mixture is as follows: the 9.5mm screening pass rate is 100%, the 7.2mm screening pass rate is 94%, the 4.75mm screening pass rate is 84%, the 2.36mm screening pass rate is 47.5%, the 1.18mm screening pass rate is 39%, the 0.6mm screening pass rate is 26.5%, the 0.3mm screening pass rate is 18.5%, the 0.15mm screening pass rate is 12.5%, and the 0.075mm screening pass rate is 8%.

[0026] In this embodiment, the particle size of the steel slag is 2.36-9.5 mm; wherein the asphalt mixture includes coarse material with a particle size of 2.36-9.5 mm, and the amount of steel slag accounts for 30%-90% of the volume ratio of the coarse material.

[0027] Specifically, when the steel slag particle size is controlled between 2.36 and 9.5 mm and the slag content accounts for 30% to 90% of the volume of the coarse material, the high hardness of the steel slag (crushing value ≤ 20%) can be used to strengthen the skeleton structure of the asphalt mixture, improve the rutting resistance and wear resistance, and the content can be flexibly adjusted to adapt to different engineering requirements: a low content (30% to 50%) can optimize the workability of the mixture and reduce the risk of construction segregation caused by the rough surface of the steel slag; a high content (70% to 90%) maximizes the utilization rate of industrial solid waste, while using the pore structure of the steel slag to improve the interfacial adhesion. This particle size range matches the requirements of the MS-3 graded coarse material, and can take into account both anti-skid and drainage performance and structural density.

[0028] In this embodiment, the filler includes mineral powder, and the particle size of the mineral powder is ≤0.075mm; among them, the mineral powder with a particle size of ≤0.075mm is used as the filler, and its fine particles can effectively fill the voids in the asphalt mixture skeleton, improve the density, and at the same time increase the contact area between the asphalt and the aggregate, and enhance the interfacial adhesion; and the mineral powder forms a "micro-macro" composite skeleton with the steel slag and the aggregate, further optimizing the deformation resistance and durability of the wear layer.

[0029] In this embodiment, the aggregate includes one or more of limestone, basalt, diabase and tuff; it can optimize the performance of the mixture through the complementary advantages of different rock properties: limestone has a high calcium carbonate content and good adhesion to asphalt, which is suitable for humid areas to enhance the ability to resist water damage; basalt / diabase has high compressive strength and wear resistance, which can improve the road surface's resistance to rutting and skid; the porous and lightweight characteristics of tuff can reduce the density of the mixture and reduce the load on the structural layer.

[0030] See also Figure 2 The present invention also provides a design method for a cold-mixed and cold-laid steel slag wearing layer material, the design method comprising: S10, select the type of raw materials for asphalt mixture according to project requirements and design the gradation type; S20, determining the amount of water added to the asphalt mixture based on the mixing test; S30, determine the asphalt-to-stone ratio of the asphalt mixture based on the wet wheel abrasion test and the load wheel sand adhesion test; S40: Prepare the steel slag cold mix and cold lay wearing layer material according to the raw material type, gradation type, external water content and oil-stone ratio and conduct performance index testing; S50, judging whether the performance indicators of the steel slag cold-mixed cold-laid wearing layer material meet the requirements. If a performance indicator does not meet the requirements, repeating steps S10 to S40 until the requirements are met, and finally completing the design of the steel slag cold-mixed cold-laid wearing layer material.

[0031] The above design method first selects the type of asphalt mixture raw materials and designs the MS-3 gradation according to the project requirements. Then, through mixing tests, the external water content of 3% to 6% of the total mass of steel slag and aggregate is determined. Then, the wet wheel abrasion test and the load wheel sand adhesion test are used to optimize the oil-stone ratio to 6% to 8%. Subsequently, the materials are configured according to the raw material type, gradation, external water content and oil-stone ratio, and performance indicators such as wear resistance and skid resistance are tested. If any indicator does not meet the requirements, iterative optimization is started from raw material selection and gradation design until the performance meets the requirements, forming a systematic material design process.

[0032] In an embodiment of the present invention, in step S10: the gradation type of the asphalt mixture is MS-3, and the raw materials of the asphalt mixture include steel slag, aggregate, emulsified asphalt, filler and external water; in step S20: the amount of external water is 3%~6% of the total mass of the steel slag and aggregate; in step S30: the oil-stone ratio of the asphalt mixture is 6%~8%.

[0033] In an embodiment of the present invention, in step S40: a rutting test is used to evaluate the high temperature performance of the steel slag cold-mixed cold-laid wearing layer material, a 6-day immersion wet wheel abrasion test is used to evaluate the water damage resistance of the steel slag cold-mixed cold-laid wearing layer material, a pendulum instrument method is used to evaluate the anti-skid performance of the steel slag cold-mixed cold-laid wearing layer material, and a slurry mixture rutting deformation test is used to evaluate the anti-rutting performance of the steel slag cold-mixed cold-laid wearing layer material.

[0034] Correspondingly, the present invention also provides an application of the above steel slag cold mix cold laid wearing layer material and / or the design method of the above steel slag cold mix cold laid wearing layer material in pavement maintenance.

[0035] The technical solution of the present invention will now be further described with reference to specific embodiments.

[0036] Example 1: This embodiment 1 first provides a steel slag cold mix cold laying wearing course material, including an MS-3 graded asphalt mixture. The raw materials of the asphalt mixture include steel slag, diabase, emulsified asphalt, mineral powder, and external water. The amount of external water is 3% to 6% of the total mass of the steel slag and aggregate. The asphalt mixture has an oil-to-stone ratio of 6% to 8%. Among them, the synthetic gradation of asphalt mixture is as follows: 9.5mm screening pass rate is 100%, 7.2mm screening pass rate is 94%, 4.75mm screening pass rate is 84%, 2.36mm screening pass rate is 47.5%, 1.18mm screening pass rate is 39%, 0.6mm screening pass rate is 26.5%, 0.3mm screening pass rate is 18.5%, 0.15mm screening pass rate is 12.5%, and 0.075mm screening pass rate is 8%.

[0037] Specifically, the particle size of the steel slag is 2.36-9.5 mm; the asphalt mixture includes coarse materials with a particle size of 2.36-9.5 mm, and the amount of the steel slag accounts for 75% of the volume ratio of the coarse materials.

[0038] This embodiment 1 also provides a design method for a cold-mixed and cold-laid steel slag wearing layer material, comprising the following steps: Step (1), gradation design of steel slag ultra-thin wearing layer material: The Technical Specifications for Preventive Maintenance of Highway Asphalt Pavement indicate that the gradation of micro-surfacing mineral materials for pre-maintenance of asphalt pavement of expressways and first-class highways is mainly MS-3. In combination with the Technical Specifications for Micro-surfacing, a special explanation is given on the gradation of MS-3 micro-surfacing mineral materials: the proportion of mineral materials with a particle size of 4.75 to 9.5 mm in this gradation is usually small, generally about 20%, and the coarse particle size of this part should also be as close to 2.36 mm as possible rather than 9.5 mm in this particle size, so as to ensure the performance of the wearing layer; the requirement for the pass rate of the 7.2 mm sieve hole is added, so the specific gradation of the MS-3 type steel slag ultra-thin wearing layer in the present invention is determined as shown in Table 1 below: Table 1 Design gradation of MS-3 asphalt mixture

[0039] Step (2), design of steel slag blending particle size and blending ratio: Compared with natural aggregate, the dust content in steel slag fine material is high, and its f-CaO content is also relatively high, which makes the volume stability difficult to control. Therefore, in this embodiment 1, steel slag is used instead of natural aggregate to design the ultra-thin wearing layer. The coarse material in the asphalt mixture refers to the part with a particle size of ≥2.36mm, and the maximum allowable particle size of the MS-3 ultra-thin wearing layer is 9.5mm. The steel slag blending particle size is determined to be 2.36~9.5mm. Since the surface of steel slag is rough and has many pores, the pores distributed on the surface of steel slag will absorb asphalt, thereby increasing the optimal oil-stone ratio of the asphalt mixture, and further increasing the economic cost of the wearing layer. Therefore, in the present invention, 75% of the 2.36~9.5mm coarse material is steel slag, and the rest is diabase.

[0040] Step (3), design of the amount of water added to the steel slag ultra-thin wearing layer material: The optimal amount of water added to the steel slag ultra-thin wearing layer asphalt mixture is determined through mixing tests. The specific test steps refer to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The mixing test ingredients are prepared according to the designed mineral gradation. The main components are diabase, steel slag and mineral powder. The specific mass distribution is shown in Table 2: Table 2 Mass distribution of aggregates in mixing test

[0041] The initial water addition rate was 4%. Based on the actual test results of this group, three parallel control tests were set up, that is, a total of four mixing tests were conducted with water addition rates of 6%, 5%, 4%, and 3%. The results of the mixing tests are shown in Table 3: Table 3 Mixing test results

[0042] It can be seen from Table 3 that the ideal mixing state should be that the asphalt mixture can be evenly adsorbed on the aggregate surface, with neither emulsion exudation nor clumping of the asphalt mixture. Therefore, the optimal external water content of the asphalt mixture for the ultra-thin wearing layer of steel slag is 5%.

[0043] Step (4), design of the optimal oil-stone ratio of the asphalt mixture of the ultra-thin steel slag wearing layer: the optimal oil-stone ratio of the asphalt mixture of the ultra-thin steel slag wearing layer is determined by a 1h wet wheel abrasion test and a load wheel sand adhesion test, wherein the former determines the minimum oil-stone ratio of the asphalt mixture and the latter determines the maximum oil-stone ratio of the asphalt mixture.

[0044] Specifically, the mass distribution of each particle group in the wet wheel abrasion test and the load wheel sand adhesion test is shown in Table 4: Table 4 Test aggregate gradation

[0045] Among them, the mass of a single specimen in the wet wheel abrasion test is 800g, and the mass of the specimen in the load wheel sand adhesion test is 500g; the gradation range unit is mm, and the mass unit of steel slag and diabase is g.

[0046] The oil-stone ratio was initially set at 7%. On this basis, five groups of control tests were conducted with oil-stone ratios of 6%, 6.5%, 7%, 7.5%, and 8%. The test results are as follows: Figure 2 shown.

[0047] Depend on Figure 2 It can be seen that according to the requirements of the specification, the effective range of the best oil-stone ratio is 6%~8%. At the same time, in order to meet the performance of both tests as much as possible, Figure 2 The horizontal coordinate value corresponding to the intersection of the two curves determines that the optimal oil-to-stone ratio of the asphalt mixture of the ultra-thin steel slag wearing layer in this embodiment 1 is 7%.

[0048] Step (5), high temperature stability test of ultra-thin steel slag wearing layer: plate-shaped specimens are prepared by wheel rolling method for rutting test, and the high temperature performance of asphalt mixture is evaluated according to the dynamic stability DS of the rutting test results; wherein, the rutting test sets 0% steel slag content as the control group to compare the performance changes of the wearing layer after steel slag replaces diabase aggregate. The test results are as follows Figure 3 shown.

[0049] Specifically, by Figure 3The data show that the dynamic stability of the ultra-thin wearing layer material with a 75% steel slag content provided in Example 1 increased by 82.5% compared to the ultra-thin wearing layer with a 0% steel slag content. This is related to the abundant angular features of the steel slag, which help increase the number of contact points within the skeleton structure. The more spherical particle shape and rough surface texture increase the contact length within the skeleton structure. The coupling of these two effects significantly improves the contact quality within the thin layer cover and the overall skeleton quality, thereby enhancing the high-temperature stability of the ultra-thin steel slag wearing layer.

[0050] Step (6), test of the water damage resistance of the ultra-thin wear layer of steel slag: a 6-day immersion wet wheel abrasion test is used to test the water damage resistance of the mixture. The evaluation index is the abrasion value, which is calculated according to formula (1): (1); In formula (1): WTAT is the abrasion value of slurry mixture (g / m 2 );m a is the mass of the sample before abrasion (g); m b is the mass of the sample after wear (g); A is the wear area of ​​the wear head hose (m 2 ).

[0051] The results of the above 6-day wet wheel wear test are as follows: Figure 4 As shown by Figure 4 The data show that the wet wheel wear value of the ultra-thin wear layer with 75% steel slag content provided in Example 1 is 28.1% lower than that of the ultra-thin wear layer with 0% steel slag content. This is because the chemical adhesion provided by the alkalinity of the steel slag, the physical anchoring effect provided by the rough surface, and the optimization of the skeleton quality by the steel slag morphology are beneficial to the water damage resistance of the ultra-thin wear layer.

[0052] Step (7), anti-skid test of the ultra-thin wearing layer of steel slag: a plate-shaped specimen prepared by the wheel rolling method is used to test the anti-skid performance of the asphalt mixture by the pendulum instrument method, and the pendulum value (BPN) is used as its evaluation index.

[0053] The test results of the above anti-slip test are as follows Figure 5 As shown, the data show that the swing value of the ultra-thin wear layer with 75% steel slag content provided in Example 1 is increased by 12.5% ​​compared with the ultra-thin wear layer with 0% steel slag content. This is because the addition of steel slag increases the number of micro-convexities and the sharpness of the peaks on the surface of the sample. When the tire contacts the surface of the wear layer, more micro-convexities and peaks will form a micro-cutting effect similar to the metal plowing effect, effectively increasing the friction resistance on the contact surface, thereby enhancing the anti-slip performance of the sample surface.

[0054] Step (8), test of the rutting resistance of the ultra-thin steel slag wearing layer: the rutting resistance of the ultra-thin steel slag wearing layer is determined by the slurry mixture rutting deformation test. The width deformation rate and rutting depth rate of the sample are calculated according to formula (2) and formula (3), where the length unit is 0.1 mm: PLD=(L b -L a )*100 / L a (2); PVD=d b *100 / d a (3); In formula (2) and formula (3), PLD is the deformation rate per unit width of the micro-surfacing specimen (%); PVD is the rutting depth rate per unit thickness of the micro-surfacing specimen (%); L a is the width of the sample before the test; L b is the width of the sample after the test; d a is the thickness of the sample before the test; d b is the thickness of the sample after the test.

[0055] The above rutting resistance test results are as follows Figure 6 and Figure 7 As shown, the test results show that the anti-rutting ability of the ultra-thin wearing layer with 75% steel slag content provided in Example 1 is better than that of the ultra-thin wearing layer with 0% steel slag content, indicating that the steel slag asphalt mixture under the designed gradation can ensure that the road has good pavement smoothness and service life when acting on the ultra-thin wearing layer.

[0056] Compared with other existing methods, the beneficial effects of the present invention include: First of all, the present invention targets the dual technical needs of efficient disposal of industrial solid waste steel slag and preventive maintenance of asphalt pavement, integrates the physical and chemical properties of steel slag materials and the advantages of ultra-thin wearing layer pre-curing technology, and proposes a method of replacing part of the aggregate with steel slag to prepare a cold-mix cold-laid ultra-thin wearing layer. The invention is based on the unique physical and chemical characteristics of steel slag materials: high fine dust content and f-CaO content, and a porous and rough structure on the surface of the steel slag. Combined with the technical advantages of the cold-mix cold-laid curing process such as normal temperature construction and rapid traffic opening, the invention innovatively uses steel slag as the main coarse aggregate to replace 75% of natural coarse aggregate (diabase), and develops a new type of environmentally friendly ultra-thin wearing layer material.

[0057] Secondly, the ultra-thin steel slag wearing layer in this invention uses an MS-3 mineral gradation, an external water content of 5%, and an optimal oil-to-stone ratio of 7%. Performance test results show that compared to conventional ultra-thin wearing layers, the ultra-thin steel slag wearing layer has an 82.5% increase in dynamic stability, a 28.1% increase in water damage resistance, and a 12.5% ​​increase in anti-skid performance, achieving a synergistic improvement in road performance and environmental benefits. This technology not only provides a new approach for the large-scale resource utilization of steel slag, but also meets the urgent needs of modern road engineering for efficient maintenance technologies and low-carbon construction processes, with significant environmental benefits and engineering application value.

[0058] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0059] The above embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A steel slag cold mix cold laying wearing layer material, characterized in that: The asphalt mixture comprises an MS-3 gradation type, wherein the raw materials of the asphalt mixture include steel slag, aggregate, emulsified asphalt, filler and external water; Among them, in the asphalt mixture: the 9.5mm screening pass rate is 100%, the 4.75mm screening pass rate is 70%~90%, the 2.36mm screening pass rate is 45%~70%, and the 0.075mm screening pass rate is 6%~12%; the amount of the external water used is 3%~6% of the total mass of the steel slag and the aggregate; the oil-stone ratio of the asphalt mixture is 6%~8%.

2. The steel slag cold mix and cold laying wearing layer material according to claim 1, characterized in that: The synthetic gradation of the asphalt mixture is as follows: the 9.5mm screening pass rate is 100%, the 7.2mm screening pass rate is 94%, the 4.75mm screening pass rate is 84%, the 2.36mm screening pass rate is 47.5%, the 1.18mm screening pass rate is 39%, the 0.6mm screening pass rate is 26.5%, the 0.3mm screening pass rate is 18.5%, the 0.15mm screening pass rate is 12.5%, and the 0.075mm screening pass rate is 8%.

3. The steel slag cold mix and cold laying wearing layer material according to claim 1, characterized in that: The particle size of the steel slag is 2.36-9.5 mm.

4. The steel slag cold mix and cold laying wearing layer material according to claim 3, characterized in that: The asphalt mixture comprises coarse material with a particle size of 2.36-9.5 mm, and the amount of the steel slag accounts for 30%-90% of the volume ratio of the coarse material.

5. The steel slag cold mix and cold laying wearing layer material according to claim 1, characterized in that: The filler includes mineral powder, and the particle size of the mineral powder is ≤0.075mm.

6. The steel slag cold mix and cold laying wearing layer material according to claim 1, characterized in that: The aggregate includes one or more of limestone, basalt, diabase and tuff.

7. A design method for a cold-mixed and cold-laid steel slag wearing layer material according to any one of claims 1 to 6, characterized in that: The design method includes: S10, selecting the type of raw materials for the asphalt mixture and designing the gradation type according to project requirements; S20, determining the amount of water added to the asphalt mixture according to a mixing test; S30, determining the asphalt-to-stone ratio of the asphalt mixture according to a wet wheel abrasion test and a load wheel sand adhesion test; S40, preparing the steel slag cold mix cold lay wearing layer material according to the raw material type, the gradation type, the external water amount, and the oil-stone ratio, and performing performance index testing; S50, judging whether the performance indicators of the steel slag cold-mixed cold-laid wearing layer material meet the requirements; if a performance indicator does not meet the requirements, repeating steps S10 to S40 until the requirements are met, and finally completing the design of the steel slag cold-mixed cold-laid wearing layer material.

8. The design method of cold-mixed cold-laid steel slag wearing layer material according to claim 7, characterized in that: In step S10, the gradation type of the asphalt mixture is MS-3, and the raw materials of the asphalt mixture include steel slag, aggregate, emulsified asphalt, filler and external water; in step S20, the amount of the external water is 3% to 6% of the total mass of the steel slag and the aggregate; in step S30, the oil-stone ratio of the asphalt mixture is 6% to 8%.

9. The design method of cold-mixed cold-laid steel slag wearing layer material according to claim 7, characterized in that: In the step S40: a rutting test is used to evaluate the high temperature performance of the cold-mixed and cold-laid steel slag wearing layer material, a 6-day immersion wet wheel abrasion test is used to evaluate the water damage resistance of the cold-mixed and cold-laid steel slag wearing layer material, a pendulum apparatus method is used to evaluate the anti-skid performance of the cold-mixed and cold-laid steel slag wearing layer material, and a slurry mixture rutting deformation test is used to evaluate the anti-rutting performance of the cold-mixed and cold-laid steel slag wearing layer material.

10. Use of the steel slag cold mix cold laid wearing layer material according to any one of claims 1 to 6 and / or the design method of the steel slag cold mix cold laid wearing layer material according to any one of claims 7 to 9 in pavement maintenance.

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