Composite modified asphalt anti-skid surface layer and preparation method thereof

Abstract

The application discloses a composite modified asphalt anti-skid surface layer and a preparation method thereof. The composite modified asphalt anti-skid surface layer comprises asphalt, aggregate and mineral powder. The aggregate has the following grading: the cumulative passing rate of the 0.075mm sieve is 4% to 10%, the cumulative passing rate of the 2.36mm sieve is 25% to 38%, and the cumulative passing rate of the 4.75mm sieve is 30% to 45%. The asphalt is rubber powder / SBS composite modified asphalt, the 60 DEG C dynamic viscosity of the asphalt is greater than or equal to 50000 Pa.s, the 180 DEG C Brookfield viscosity is less than 2 Pa.s, and the 25 DEG C elastic recovery is greater than or equal to 85%. The application can improve the anti-skid ability and anti-rutting ability of the asphalt pavement under high-temperature and humid environment.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, and in particular to a composite modified asphalt antiskid surface layer and its preparation method. Background Technology

[0002] Southern my country's hot and humid regions generally face prolonged periods of high temperatures, frequent rainfall, and heavy traffic, making asphalt pavements highly susceptible to rutting and rapid deterioration of skid resistance. This results in shortened pavement life and significantly increased maintenance costs. Existing asphalt mixtures often use base asphalt combined with AC-graded or SMA-graded aggregates. While this improves rutting resistance at high temperatures, its skid resistance is easily compromised in hot and humid environments, posing a significant challenge under heavy, humid loads. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a composite modified asphalt anti-skid surface layer and its preparation method, which can improve the anti-skid ability and rutting resistance of asphalt pavement under high temperature and humid conditions.

[0004] To address the aforementioned problems, this invention discloses a composite modified asphalt anti-skid surface layer, comprising asphalt, aggregate, and mineral powder; the aggregate gradation is as follows: cumulative passing rate through a 0.075mm sieve is 4%~10%, cumulative passing rate through a 2.36mm sieve is 25%~38%, and cumulative passing rate through a 4.75mm sieve is 30%~45%; the asphalt is a rubber powder / SBS composite modified asphalt, and the asphalt has a dynamic viscosity at 60℃ ≥50000Pa·s, a Brookfield viscosity at 180℃ <2Pa·s, and an elastic recovery at 25℃ ≥85%.

[0005] As an improvement to the above technical solution, the aggregate gradation is as follows: the cumulative passing rate of 0.075mm sieve openings is 4%~10%, the cumulative passing rate of 0.15mm sieve openings is 7%~14%, the cumulative passing rate of 0.3mm sieve openings is 10%~18%, the cumulative passing rate of 0.6mm sieve openings is 12%~24%, the cumulative passing rate of 1.18mm sieve openings is 18%~30%, the cumulative passing rate of 2.36mm sieve openings is 25%~38%, the cumulative passing rate of 4.75mm sieve openings is 30%~45%, the cumulative passing rate of 9.5mm sieve openings is 90%~100%, and the cumulative passing rate of 13.2mm sieve openings is 100%.

[0006] As an improvement to the above technical solution, the aggregate includes a first aggregate with a particle size of 0-3mm, a second aggregate with a particle size of 3mm-5mm, and a third aggregate with a particle size of 5mm-10mm; The aggregate includes limestone and / or diabase; The apparent relative density of the aggregate is ≥2.6 g / cm³. 3Strength ≤ 6%.

[0007] As an improvement to the above technical solution, the porosity of the composite modified asphalt anti-skid surface layer is 3.5%~4.5%; the asphalt-aggregate ratio of the composite modified asphalt anti-skid surface layer is 5.2%~5.4%.

[0008] As an improvement to the above technical solution, the rubber powder / SBS composite modified asphalt comprises the following raw materials in parts by weight: 100 parts of base asphalt, 4-7 parts of SBS, 20-30 parts of rubber powder, 0.3-0.6 parts of anti-rutting agent, 3-5 parts of compatibilizer, and 0.1-0.3 parts of stabilizer.

[0009] As an improvement to the above technical solution, the particle size of the rubber powder is 40 mesh to 60 mesh; The SBS is a linear styrene-butadiene-styrene block copolymer with a molecular weight of 100,000 to 150,000 and a block ratio of 30:70.

[0010] As an improvement to the above technical solution, the preparation method of the rubber powder / SBS composite modified asphalt is as follows: The base bitumen is heated to 150℃~160℃, SBS is added, and high-speed shearing is performed for 50min~70min to obtain the first binder. The rubber powder is dried and then sheared for desulfurization. The first binder is heated to 170℃~190℃, and the rubber powder is added in batches. The mixture is stirred and swollen to obtain the second binder. Add anti-rutting agent, compatibilizer and stabilizer to the second binder in sequence, and stir at low speed for 8 min to 15 min to obtain the third binder; The third binder is heated to 175~180℃, subjected to high-speed shearing for 60min~80min, and developed at 175~180℃ for 2.5h~3.5h to obtain the rubber powder / SBS composite modified asphalt.

[0011] As an improvement to the above technical solution, the rotation speed of the high-speed shearing is 4000 r / min to 4500 r / min; the rotation speed of the low-speed stirring is 800 r / min to 1200 r / min; and the rotation speed during the development process is 1300 r / min to 1800 r / min.

[0012] Accordingly, the present invention also discloses a method for preparing the above-mentioned composite modified asphalt anti-skid surface layer, comprising the following steps: The aggregate gradation is determined as follows: the cumulative passing rate of the 0.075mm sieve is 4%~10%, the cumulative passing rate of the 2.36mm sieve is 25%~38%, and the cumulative passing rate of the 4.75mm sieve is 30%~45%. The optimal asphalt-aggregate ratio was determined experimentally based on the aggregate gradation and target void ratio. Aggregates, mineral powder, and asphalt are mixed according to the aggregate blending ratio and the asphalt-aggregate ratio to obtain the composite modified asphalt anti-skid surface layer; the asphalt is rubber powder / SBS composite modified asphalt.

[0013] As an improvement to the above technical solution, the step of mixing aggregates, mineral powder, and asphalt to obtain the composite modified asphalt anti-skid surface layer includes the following steps: The aggregates and mineral powder are dried to constant weight; the aggregates include a first aggregate, a second aggregate, and a third aggregate. The first aggregate, the second aggregate, and the third aggregate are mixed evenly and heated to the mixing temperature for later use; the mineral powder and the asphalt are heated to the mixing temperature for later use; the mixing temperature is 180℃~185℃; The first aggregate, the second aggregate, and the third aggregate are mixed for 80-100 seconds, the asphalt is added and mixed for 80-100 seconds, the mineral powder is added and mixed for 80-100 seconds, and the mixture is stirred evenly at the mixing temperature to obtain the composite modified asphalt anti-skid surface layer.

[0014] Implementing this invention has the following beneficial effects: The composite modified asphalt anti-skid surface layer provided by this invention optimizes aggregate gradation. A cumulative passing rate through a 4.75mm sieve ensures the formation of the main skeleton, with more than 30 skeleton contact points in the mixture, achieving superior high-temperature rutting resistance. A cumulative passing rate through a 2.36mm sieve avoids abrupt phase transformation problems in traditional designs, preventing localized stress concentration and agglomeration of aggregates during compaction, significantly reducing segregation sensitivity and improving workability. A cumulative passing rate through a 0.075mm sieve ensures asphalt-aggregate interface strength, reducing asphalt mixture agglomeration and ensuring effective asphalt adsorption. The asphalt used is a rubber powder / SBS composite modified asphalt with good thermal stability. Through the combination of asphalt and graded aggregates, it is not prone to delamination under high temperature and humidity. The composite modified asphalt anti-skid surface layer features outstanding anti-skid performance, high temperature resistance, and long service life, thereby effectively reducing maintenance and operating costs. Attached Figure Description

[0015] Figure 1 This is a surface view of a rutted slab obtained from the preparation of the composite modified asphalt antiskid surface layer provided by the present invention; Figure 2 This is a schematic diagram of the identification area of ​​the initial skeleton contact point of the composite modified asphalt anti-skid surface layer provided by the present invention; Figure 3 This is a cross-sectional schematic diagram of the identification area of ​​the initial skeleton contact point of the composite modified asphalt anti-skid surface layer provided by the present invention; Figure 4This is a schematic diagram of the identification area of ​​the initial skeleton contact point of the composite modified asphalt anti-skid surface layer provided by the present invention after binarization processing; Figure 5 This is a schematic diagram of the identification area of ​​the initial skeleton contact point of the composite modified asphalt antiskid surface layer provided by the present invention before corrosion and expansion. Figure 6 This is a schematic diagram of the identification area of ​​the initial skeleton contact point of the composite modified asphalt antiskid surface layer provided by the present invention after corrosion and expansion; Figure 7 This is a schematic diagram of the identification area of ​​the initial skeleton contact point of the composite modified asphalt anti-skid surface layer provided by the present invention after edge delineation; Figure 8 This is a schematic diagram of the identification area of ​​the initial skeleton contact point of the composite modified asphalt anti-skid surface layer provided by the present invention after particle marking; Figure 9 This is a schematic diagram illustrating the process of identifying the initial skeleton contact points of the composite modified asphalt anti-skid surface layer provided by the present invention; Figure 10 This is a schematic diagram illustrating the identification principle of the initial skeleton contact points of the composite modified asphalt anti-skid surface layer provided by the present invention; Figure 11 This is a schematic diagram illustrating the identification principle of the initial skeleton contact points of the composite modified asphalt anti-skid surface layer provided by the present invention; Figure 12 This is a schematic diagram illustrating the attenuation of the anti-skid performance of the composite modified asphalt anti-skid surface layer provided by the present invention; Figure 13 This is a schematic diagram illustrating the rutting depth development of the composite modified asphalt antiskid surface layer provided by the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0017] This invention provides a composite modified asphalt anti-skid surface layer, comprising asphalt, aggregate, and mineral powder; the aggregate gradation is as follows: the cumulative passing rate through a 0.075mm sieve is 4%~10%, the cumulative passing rate through a 2.36mm sieve is 25%~38%, and the cumulative passing rate through a 4.75mm sieve is 30%~45%; the asphalt is a rubber powder / SBS composite modified asphalt, and the asphalt has a dynamic viscosity at 60℃ ≥50000Pa·s, a Brookfield viscosity at 180℃ <2Pa·s, and an elastic recovery at 25℃ ≥85%.

[0018] The composite modified asphalt anti-skid surface layer provided by this invention optimizes the aggregate gradation. The cumulative passing rate through a 4.75mm sieve is 30%~45%, ensuring the formation of the main skeleton. The number of skeleton contact points in the mixture is greater than 30, achieving superior high-temperature rutting resistance. The cumulative passing rate through a 2.36mm sieve is 25%~38%, avoiding the abrupt phase transformation problem in traditional designs, preventing local stress concentration and agglomeration of aggregates during compaction, significantly reducing segregation sensitivity and improving workability. The cumulative passing rate through a 0.075mm sieve is 4%~10%, ensuring the asphalt-aggregate interface strength, reducing asphalt mixture agglomeration, and ensuring effective asphalt adsorption. The asphalt used is a rubber powder / SBS composite modified asphalt with good thermal stability. Through the combination of asphalt and graded aggregates, it is not prone to delamination under high temperature and humidity. The composite modified asphalt anti-skid surface layer has outstanding anti-skid performance, high temperature resistance, and long service life, thereby effectively reducing maintenance and operating costs.

[0019] After determining the cumulative passing rates of 0.075mm, 4.75mm, and 2.36mm sieve apertures, the aggregate gradation curve was further optimized based on the fractal dimension. The fractal dimension was determined using the fractal expression of the cumulative passing rate of the aggregate, as follows:

[0020] In the formula, x is the sieve aperture size, x max Where is the maximum sieve aperture size, and D is the fractal dimension.

[0021] Based on the cumulative passing rates of 0.075mm, 2.36mm, and 4.75mm sieve apertures determined according to this invention, a piecewise fractal expression for the cumulative passing rate of aggregates is obtained, as follows:

[0022] In the formula, d is the sieve aperture size, d max Let D1 be the maximum sieve aperture size, D2 be the fractal dimensions of different segments, and A and B be constants. A is 0.45 and B is 0.25.

[0023] The fractal dimensions are shown in Table 1.

[0024] Table 1. Selection of Fractal Dimension Parameters

[0025] Determine the target values ​​D1, D2, and D3, and design the corresponding gradation. The final preferred gradation of the coarse aggregate is as follows: cumulative passing rate of 4%~10% for 0.075mm sieve openings, 7%~14% for 0.15mm sieve openings, 10%~18% for 0.3mm sieve openings, 12%~24% for 0.6mm sieve openings, 18%~30% for 1.18mm sieve openings, 25%~38% for 2.36mm sieve openings, 30%~45% for 4.75mm sieve openings, 90%~100% for 9.5mm sieve openings, and 100% for 13.2mm sieve openings.

[0026] A sieve aperture of 9.5mm~13.2mm primarily controls the stability of the coarse skeleton while ensuring that 90% of the asphalt mixture does not segregate, retaining a small amount of buffer particles; 4.75mm serves as the dividing point between coarse and fine particles, and a pass rate of ≥30% ensures the formation of the main skeleton; a cumulative pass rate of 30%~45% guarantees that the number of skeleton contact points in the mixture is greater than 30, achieving superior high-temperature rutting resistance; a sieve aperture of 0.6mm~2.36mm is in the transition zone, with the upper limit of pass rate increasing from 24% to 38%, and the lower limit... The pass rate is increased from 12% to 25%, preventing excessive fine aggregates from causing an excessively large specific surface area. The 2.36mm sieve aperture serves as a secondary skeleton node, and the cumulative pass rate of 25%~38% solves the problem of abrupt phase transformation in gradation design, preventing local stress concentration and agglomeration of aggregates during compaction, significantly reducing segregation sensitivity and improving workability. The cumulative pass rate of the 0.075mm sieve aperture is 4%~10%, ensuring the asphalt-aggregate interface strength, reducing asphalt mixture agglomeration, and ensuring effective asphalt adsorption. Comparative analysis shows that the fatigue life of asphalt mixtures prepared using the gradation provided by this invention is more than 10% higher than that of conventional gradations.

[0027] Understandably, the skid resistance and rutting resistance of asphalt anti-skid surfaces both depend on a stable aggregate skeleton and sufficient bond strength. However, there is a certain contradiction between skid resistance and rutting resistance. To improve skid resistance, the porosity of the asphalt mixture is usually increased, or a single large-diameter aggregate is used to provide sufficient texture to improve friction between the tire and the road surface. However, correspondingly, a single large-diameter aggregate and excessive porosity will result in a loose skeleton, which is not conducive to improving rutting resistance.

[0028] In a preferred embodiment, the aggregate comprises a first aggregate with a particle size of 0-3 mm, a second aggregate with a particle size of 3 mm-5 mm, and a third aggregate with a particle size of 5 mm-10 mm. Specifically, by mass percentage, the aggregate comprises 28%-35% of the first aggregate with a particle size of 0-3 mm, 5%-12% of the second aggregate with a particle size of 3 mm-5 mm, and 56%-62% of the third aggregate with a particle size of 5 mm-10 mm. Compared to aggregates with a single particle size, using the first aggregate with a particle size of 0-3 mm as fine aggregate, and the second aggregate with a particle size of 3 mm-5 mm and the third aggregate with a particle size of 5 mm-10 mm as coarse aggregate, improves the skeleton stability. Combined with continuous gradation, it achieves synergistic optimization of rutting resistance and skid resistance.

[0029] Optionally, the aggregate may include limestone and / or diabase, without specific limitation. The apparent relative density of the aggregate is ≥2.6 g / cm³. 3 Strength ≤ 6%.

[0030] To further improve the rutting and skid resistance of the composite modified asphalt anti-skid surface layer, the porosity of the surface layer is controlled at 3.5% to 4.5%. If the porosity is less than 3.5%, there is too much free asphalt, which overfills the aggregate skeleton, significantly reducing the mechanical engagement points between the tire and the road surface, resulting in poor skid resistance. If the porosity is greater than 4.5%, the skeleton is loose, and under repeated vehicle loads at high temperatures, the aggregate is prone to relative slippage, leading to overall flow deformation of the composite modified asphalt anti-skid surface layer and low rutting resistance. Specifically, in one embodiment, the asphalt-aggregate ratio of the composite modified asphalt anti-skid surface layer is 5.2% to 5.4%.

[0031] It is understandable that conventional asphalt, when combined with the graded aggregates provided by this invention, can initially meet the requirements for skid resistance and rutting resistance. However, in high-temperature and humid environments, the fluidity of conventional asphalt increases, and under long-term loads with high traffic volume, its skid resistance and rutting resistance deteriorate significantly. Therefore, conventional asphalt is modified to improve its high-temperature stability. In one embodiment, the rubber powder / SBS composite modified asphalt comprises the following raw materials in parts by weight: 100 parts base asphalt, 4-7 parts SBS, 20-30 parts rubber powder, 0.3-0.6 parts anti-rutting agent, 3-5 parts compatibilizer, and 0.1-0.3 parts stabilizer.

[0032] In one embodiment, the rubber powder has a particle size of 40-60 mesh. Preferably, the rubber powder is obtained through the recycling and processing of waste tires.

[0033] In one embodiment, the SBS is a linear styrene-butadiene-styrene block copolymer with a molecular weight of 100,000 to 150,000 and a block ratio of 30:70.

[0034] Rubber powder and SBS work synergistically to form a structurally stable cross-linked system with certain elastic properties. By limiting the particle size of the rubber powder, the molecular weight of the SBS, and the block ratio, the high-temperature stability, low-temperature crack resistance, and aging resistance of asphalt can be effectively improved.

[0035] Furthermore, the compatibilizer is used to improve the compatibility of the base asphalt with non-polar polymers such as SBS and rubber powder. Optionally, the compatibilizer is an aromatic oil.

[0036] The stabilizer is used to improve the stability of the modified asphalt during storage. Optionally, the stabilizer is epoxy resin and sulfur powder, preferably, the mass ratio of epoxy resin to sulfur powder is 3:2.

[0037] The base asphalt is 70# base asphalt.

[0038] The composite modification of rubber powder and SBS still suffers from problems such as insufficient interphase compatibility. Therefore, in a preferred embodiment, the rubber powder is pretreated by alkaline washing, in which the rubber powder is stirred and soaked in Na2CO3 solution to improve the compatibility between the rubber powder and the base asphalt.

[0039] More preferably, the alkali-washed pretreated rubber powder is modified to obtain modified rubber powder. Specifically, the modified rubber powder comprises the following raw materials in the indicated mass percentages: 88%~92% alkali-washed pretreated rubber powder, 4%~7% wollastonite fiber, 3%~6% polyacrylamide, and 0.5%~2% carboxymethyl starch. Wollastonite fiber provides dispersibility and acts as a reinforcing agent to provide certain high-temperature rutting resistance; polyacrylamide can be grafted onto the surface of the rubber powder to improve the interfacial compatibility between the rubber powder and SBS and asphalt; carboxymethyl starch can prevent the agglomeration of the rubber powder and enhance the bonding strength between the matrix asphalt and the rubber powder. The three components synergistically form a three-dimensional network structure, which can improve the compatibility of the rubber powder with SBS and asphalt and reduce the probability of agglomeration of the rubber powder at high temperatures.

[0040] In one embodiment, the asphalt is prepared as follows: S11. Heat the base asphalt to 150℃~160℃, add SBS, and shear at high speed for 50min~70min to obtain the first binder.

[0041] The rotational speed of the high-speed shearing is 4000 r / min to 4500 r / min.

[0042] S12. Dry the rubber powder and perform shear desulfurization.

[0043] Specifically, in one embodiment, the shear desulfurization includes the following steps: S121. Grind the rubber powder, separate and sieve it, and dry it in an oven at 80℃~100℃ for 2h~4h.

[0044] In a preferred embodiment, the separated and sieved rubber powder is pretreated, the pretreatment comprising: soaking the separated and sieved rubber powder in a 1mol / L~5mol / L Na2CO3 solution at 40℃~50℃ for 1h~2h with stirring, and washing with deionized water until neutral.

[0045] More preferably, the pretreated rubber powder is modified to obtain modified rubber powder. Specifically, the modification includes the following steps: mixing the pretreated rubber powder, wollastonite fiber and polyacrylamide, stirring at 90℃~100℃ for 30min~45min at a speed of 1200r / min~1500r / min; adding a 5%~8% carboxymethyl starch aqueous solution, continuing to stir for 20min~30min, and drying to obtain the modified rubber powder.

[0046] S122. Shear desulfurization is carried out by co-rotating twin-screw extrusion process, with a rotation speed of 500 r / min to 800 r / min and a temperature of 200℃ to 260℃.

[0047] S13. Heat the first binder to 170℃~190℃, add the rubber powder in batches, stir and swell to obtain the second binder.

[0048] Specifically, the rubber powder is added in three batches, each batch consisting of 8-10 parts by weight. This allows sufficient time and space for the rubber powder to disperse and swell, resulting in a uniform and stable second binder. The stirring speed during the process is 800-1200 rpm.

[0049] S14. Add anti-rutting agent, compatibilizer and stabilizer to the second binder in sequence, and stir at low speed for 8 min to 15 min to obtain the third binder.

[0050] The speed of the low-speed stirring is 800 r / min to 1200 r / min.

[0051] S15. The third binder is heated to 175~180℃, subjected to high-speed shearing for 60min~80min, and developed at 175~180℃ for 2.5h~3.5h to obtain the asphalt.

[0052] The high-speed shearing rotation speed is 4000 r / min to 4500 r / min. The rotation speed during the development process is 1300 r / min to 1800 r / min.

[0053] Accordingly, the present invention also discloses a method for preparing the above-mentioned composite modified asphalt anti-skid surface layer, comprising the following steps: S21. Determine the coarse aggregate gradation. The coarse aggregate gradation is as follows: the cumulative passing rate of the 0.075mm sieve is 4%~10%, the cumulative passing rate of the 2.36mm sieve is 25%~38%, and the cumulative passing rate of the 4.75mm sieve is 30%~45%.

[0054] S22. The aggregate and asphalt are mixed to obtain the composite modified asphalt anti-skid surface layer. The aggregate includes coarse aggregate, and the asphalt is rubber powder / SBS composite modified asphalt.

[0055] In one implementation, S22 includes the following steps: S221. Dry the aggregate to constant weight; the aggregate includes coarse aggregate, fine aggregate and mineral powder.

[0056] S222. Mix the coarse aggregate and fine aggregate evenly and heat to the mixing temperature for later use; heat the mineral powder and the asphalt separately to the mixing temperature for later use; the mixing temperature is 170℃~180℃.

[0057] S223. Stir the coarse aggregate and fine aggregate for 80s~100s, add the asphalt and mix for 80s~100s, add the mineral powder and mix for 80s~100s, and mix evenly at the mixing temperature to obtain the composite modified asphalt anti-skid surface layer.

[0058] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides a composite modified asphalt anti-skid surface layer, comprising asphalt, aggregate, and mineral powder. The asphalt is a rubber powder / SBS composite modified asphalt, comprising the following raw materials in parts by weight: 100 parts base asphalt, 5 parts SBS, 24 parts rubber powder, 0.4 parts anti-rutting agent, 4 parts compatibilizer, and 0.2 parts stabilizer.

[0059] The preparation method of rubber powder / SBS composite modified asphalt includes the following steps: S11. Heat the base asphalt to 150℃, add SBS, and shear at 4200r / min for 60min to obtain the first binder.

[0060] S12. Dry the rubber powder and perform shear desulfurization. Specifically, this includes the following steps: S121. Grind the rubber powder, separate and sieve it, and dry it in an oven at 90℃ for 3 hours.

[0061] S122. Shear desulfurization is carried out by co-rotating twin-screw extrusion process at a speed of 700 r / min and a temperature of 240℃.

[0062] S13. Heat the first binder to 180℃, add rubber powder in three batches, each batch consisting of 8 parts, and stir at 1000r / min for 30min to obtain the second binder.

[0063] S14. Add anti-rutting agent, compatibilizer and stabilizer to the second binder in sequence, stir at 1000 r / min for 10 min to obtain the third binder.

[0064] S15. The third binder is heated to 180℃, sheared at 4000r / min for 60min, and developed at 175℃ at 1500r / min for 3h to obtain rubber powder / SBS composite modified asphalt.

[0065] The aggregate gradation is shown in Table 2.

[0066] Table 2 Grading Parameters

[0067] The aggregates include limestone with a particle size of 0-3 mm, diabase with a particle size of 3-5 mm, and diabase with a particle size of 5-10 mm. The performance indicators are shown in Tables 3-5.

[0068] Table 3 Performance Indicators of Diabase (3mm~5mm)

[0069] Table 4 Performance Indicators of Diabase (5mm~10mm)

[0070] Table 5 Performance Indicators of Limestone (0~3mm)

[0071] Example 2 This embodiment provides a composite modified asphalt anti-skid surface layer, which differs from Embodiment 1 in that the rubber powder is modified rubber powder, comprising the following raw materials by mass percentage: 90% alkali-washed pretreated rubber powder, 5% wollastonite fiber, 4% polyacrylamide, and 1% carboxymethyl starch. The preparation steps are as follows: the separated and sieved rubber powder is stirred and soaked in a 1 mol / L Na2CO3 solution at 40°C for 1.5 h, then washed with deionized water until neutral to obtain alkali-washed pretreated rubber powder; the alkali-washed pretreated rubber powder, wollastonite fiber, and polyacrylamide are mixed and stirred at 90°C for 30 min at a speed of 1500 r / min; a 5% carboxymethyl starch aqueous solution is added, and stirring continues for 30 min; after drying, the modified rubber powder is obtained.

[0072] Everything else is the same as in Example 1.

[0073] Comparative Example 1 This comparative example provides a common anti-skid surface layer, which differs from Example 1 in that the aggregate uses AC gradation, as shown in Table 6.

[0074] Table 6 Grading Parameters

[0075] Everything else is the same as in Example 1.

[0076] Comparative Example 2 This comparative example provides a common anti-skid surface layer, which differs from Example 1 in that the aggregate uses SMA gradation, as shown in Table 7.

[0077] Table 7 Grading Parameters

[0078] Everything else is the same as in Example 1.

[0079] Comparative Example 3 This comparative example provides a common anti-skid surface layer, which differs from Example 1 in that the asphalt is rubber asphalt. The rubber asphalt comprises the following raw materials in parts by weight: 100 parts base asphalt, 30 parts rubber powder, 0.2 parts sulfur, and 8 parts activator.

[0080] Everything else is the same as in Example 1.

[0081] Comparative Example 4 This comparative example provides a common anti-skid surface layer, which differs from Example 1 in that the asphalt is SBS modified asphalt. The SBS modified asphalt comprises the following raw materials in parts by weight: 100 parts base asphalt, 12 parts dimethylformamide, 7 parts SBS, 0.3 parts sulfur, 2 parts triethanolamine, and 4 parts extracted oil.

[0082] Everything else is the same as in Example 1.

[0083] Performance testing: (1) Asphalt properties: The properties of the asphalt prepared in Example 1, Comparative Example 3 and Comparative Example 4 were measured, and the specific results are shown in Table 8.

[0084] Table 8 Asphalt Properties

[0085] (2) Performance of anti-skid asphalt surface layer: The performance of the anti-skid asphalt surface layer prepared in Example 1, Example 2, and Comparative Examples 1 to 4 was measured, and the specific results are shown in Table 9.

[0086] Table 9. Antiskid Surface Layer Properties of Asphalt

[0087] (3) Initial performance of asphalt anti-skid surface layer: Rutting slabs were prepared from the asphalt anti-skid surface layer. The initial performance of the asphalt anti-skid surface layer was evaluated based on the initial skeleton contact points, initial friction coefficient, and piling area of ​​the unloaded asphalt anti-skid surface layer. A 400mm×300mm×50mm rutting slab was selected. The surface of the rutting slab was as follows: Figure 1 As shown, the rut plate is cut along the width centerline (i.e., I-I), and the cross-section of the middle 200mm section is used to identify the initial skeleton contact points. The identification method is as follows: grayscale processing → Gaussian denoising → binarization → erosion and dilation → edge depiction → particle marking → contact point identification. The schematic diagram of the identification area is shown below. Figure 2 As shown, the cross-sectional view of the identified area is as follows: Figure 3 As shown, the identification method is as follows Figures 4-8 As shown. After particle labeling is completed, as... Figures 9-11 As shown, taking particles A and B as examples, point O on particle A and point M on particle B are selected, and their connection is recorded. Then, the entire particle B is traversed, and its length is recorded for each connection. Next, the next point O' on particle A and point M' on particle B are selected, and their connection is recorded. This process is repeated, traversing all points on particle B and recording their lengths. Finally, the minimum length L is obtained using an algorithm. The minimum distance between particles A and B is set to L. min When L <L min If particles A and B are in contact, this is recorded as an initial skeleton contact point. Scores are calculated for the initial skeleton contact point, initial friction coefficient, and agglomeration area of ​​the unloaded asphalt anti-skid surface layer. The scores are then summed. The scoring criteria and the correspondence between the scores and the rating of the asphalt anti-skid surface layer are shown in Tables 10 and 11, respectively.

[0088] Table 10 Scoring Criteria

[0089] Table 11 Correspondence between scores and ratings of anti-slip surface

[0090] The initial performance of the asphalt antiskid surface layers obtained in Examples 1, 2, and Comparative Examples 1 to 4 was evaluated, and the specific results are shown in Table 12.

[0091] Table 12 Initial properties of anti-slip surface layer

[0092] (4) Performance of the asphalt anti-skid surface layer after loading: Rutting slabs were prepared by using the asphalt anti-skid surface layer. The performance of the asphalt anti-skid surface layer after loading was evaluated based on the friction coefficient and rutting depth. The evaluation criteria are shown in Table 13. After a specified number of loading cycles, if the friction coefficient is ≥60 and the rutting depth is 0~2mm, it is rated as excellent, and so on.

[0093] Table 13 Evaluation Criteria

[0094] The performance of the asphalt antiskid surface layers obtained in Examples 1, 2, and Comparative Examples 1 to 4 was evaluated after loading. The specific results are shown in Table 14. Figure 12 and Figure 13 As shown.

[0095] Table 14 Post-load performance of asphalt anti-skid surface layer

[0096] (5) Comprehensive Performance of Asphalt Anti-skid Surface Layer: The comprehensive performance of the asphalt anti-skid surface layer is evaluated based on its initial performance and its performance after loading. For the initial performance, good, qualified, and unqualified are scored as 2, 1, and 0 respectively. For the performance after 200,000 loading cycles, excellent, medium, and poor are scored as 2, 1, and 0 respectively. The scores obtained from the initial performance and the performance after loading are added together to comprehensively evaluate the performance of the asphalt anti-skid surface layer. The correspondence between the scores and the comprehensive performance rating of the asphalt anti-skid surface layer is shown in Table 15.

[0097] Table 15 Correspondence between scores and the comprehensive performance rating of asphalt anti-skid surface layer

[0098] The comprehensive performance of the asphalt antiskid surface layers obtained in Examples 1, 2, and Comparative Examples 1 to 4 was evaluated, and the specific results are shown in Table 16.

[0099] Table 16 Comprehensive Performance of Asphalt Anti-skid Surface Layer

[0100] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A composite modified asphalt anti-skid surface layer, characterized in that, It includes asphalt, aggregates, and mineral powder; the aggregates have the following gradation: a cumulative passing rate of 4%~10% through a 0.075mm sieve, a cumulative passing rate of 25%~38% through a 2.36mm sieve, and a cumulative passing rate of 30%~45% through a 4.75mm sieve; the asphalt is a rubber powder / SBS composite modified asphalt, with a dynamic viscosity at 60℃ ≥50000Pa·s, a Brookfield viscosity at 180℃ <2Pa·s, and an elastic recovery at 25℃ ≥85%.

2. The composite modified asphalt anti-skid surface layer as described in claim 1, characterized in that, The aggregate gradation is as follows: cumulative passing rate of 4%~10% for 0.075mm sieve, 7%~14% for 0.15mm sieve, 10%~18% for 0.3mm sieve, 12%~24% for 0.6mm sieve, 18%~30% for 1.18mm sieve, 25%~38% for 2.36mm sieve, 30%~45% for 4.75mm sieve, 90%~100% for 9.5mm sieve, and 100% for 13.2mm sieve.

3. The composite modified asphalt anti-skid surface layer as described in claim 1, characterized in that, The aggregate includes a first aggregate with a particle size of 0-3 mm, a second aggregate with a particle size of 3 mm-5 mm, and a third aggregate with a particle size of 5 mm-10 mm; The aggregate includes limestone and / or diabase; The apparent relative density of the aggregate is ≥2.6 g / cm³. 3 Strength ≤ 6%.

4. The composite modified asphalt anti-skid surface layer as described in claim 1, characterized in that, The porosity of the composite modified asphalt antiskid surface layer is 3.5%~4.5%; the asphalt-aggregate ratio of the composite modified asphalt antiskid surface layer is 5.2%~5.4%.

5. The composite modified asphalt anti-skid surface layer as described in claim 1, characterized in that, The rubber powder / SBS composite modified asphalt comprises the following raw materials in parts by weight: 100 parts base asphalt, 4-7 parts SBS, 20-30 parts rubber powder, 0.3-0.6 parts anti-rutting agent, 3-5 parts compatibilizer, and 0.1-0.3 parts stabilizer.

6. The composite modified asphalt anti-skid surface layer as described in claim 5, characterized in that, The particle size of the rubber powder is 40 mesh to 60 mesh; The SBS is a linear styrene-butadiene-styrene block copolymer with a molecular weight of 100,000 to 150,000 and a block ratio of 30:

70.

7. The composite modified asphalt anti-skid surface layer as described in claim 5, characterized in that, The preparation method of the rubber powder / SBS composite modified asphalt is as follows: The base bitumen is heated to 150℃~160℃, SBS is added, and high-speed shearing is performed for 50min~70min to obtain the first binder. The rubber powder is dried and then sheared for desulfurization. The first binder is heated to 170℃~190℃, and the rubber powder is added in batches. The mixture is stirred and swollen to obtain the second binder. Add anti-rutting agent, compatibilizer and stabilizer to the second binder in sequence, and stir at low speed for 8 min to 15 min to obtain the third binder; The third binder is heated to 175~180℃, subjected to high-speed shearing for 60min~80min, and developed at 175~180℃ for 2.5h~3.5h to obtain the rubber powder / SBS composite modified asphalt.

8. The composite modified asphalt anti-skid surface layer as described in claim 7, characterized in that, The high-speed shearing speed is 4000 r / min to 4500 r / min; the low-speed stirring speed is 800 r / min to 1200 r / min; and the stirring speed during the development process is 1300 r / min to 1800 r / min.

9. A method for preparing a composite modified asphalt anti-skid surface layer as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The aggregate gradation is determined as follows: the cumulative passing rate of the 0.075mm sieve is 4%~10%, the cumulative passing rate of the 2.36mm sieve is 25%~38%, and the cumulative passing rate of the 4.75mm sieve is 30%~45%. The optimal asphalt-aggregate ratio was determined experimentally based on the aggregate gradation and target void ratio. Aggregates, mineral powder, and asphalt are mixed according to the aggregate blending ratio and the asphalt-aggregate ratio to obtain the composite modified asphalt anti-skid surface layer; the asphalt is rubber powder / SBS composite modified asphalt.

10. The method for preparing the composite modified asphalt anti-skid surface layer as described in claim 9, characterized in that, The process of mixing aggregates, mineral powder, and asphalt to obtain the composite modified asphalt anti-skid surface layer includes the following steps: The aggregates and mineral powder are dried to constant weight; the aggregates include a first aggregate, a second aggregate, and a third aggregate. The first aggregate, the second aggregate, and the third aggregate are mixed evenly and heated to the mixing temperature for later use; the mineral powder and the asphalt are heated to the mixing temperature for later use; the mixing temperature is 180℃~185℃; The first aggregate, the second aggregate, and the third aggregate are mixed for 80-100 seconds, the asphalt is added and mixed for 80-100 seconds, the mineral powder is added and mixed for 80-100 seconds, and the mixture is stirred evenly at the mixing temperature to obtain the composite modified asphalt anti-skid surface layer.

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