Silicon oxide modified high-viscosity anti-rutting asphalt concrete and preparation method thereof

Abstract

The invention relates to the technical field of nano modification of asphalt-based composite materials, in particular to silicon oxide modified high-viscosity anti-rutting asphalt concrete and a preparation method thereof, and the silicon oxide modified high-viscosity anti-rutting asphalt concrete is composed of matrix asphalt, a core-shell structure silicon oxide modifier, a graphene-butadiene styrene rubber composite high-viscosity agent and the like; the core-shell structure silicon oxide modifier is prepared by special coating and in-situ polymerization of a composite high-viscosity agent; basalt-polyester hybrid fiber, multi-graded limestone aggregate and nano clay-mineral powder composite filler are also used; the preparation method comprises the following steps: preparing the modifier, preparing the composite high-viscosity agent and the like, wherein specific conditions and parameters are controlled in each step. By innovating the materials and the process, the properties such as rut resistance, low-temperature crack resistance, water stability and the like are improved, the compatibility and dispersity of the materials are improved, the durability is enhanced, the service life of the pavement is prolonged, and economic and social benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of nano - modification of asphalt - based composite materials, and particularly to a silica - modified high - viscosity rut - resistant asphalt concrete and its preparation method. Background Art

[0002] With the rapid development of China's transportation industry, the volume of highway transportation has been increasing day by day, the vehicle load has been continuously increasing, and higher requirements have been put forward for the performance of asphalt concrete pavements. Rutting is one of the common diseases of asphalt concrete pavements, which seriously affects the smoothness, driving comfort and safety of the pavement, shortens the service life of the pavement, and increases the maintenance cost. Therefore, the research and development of high - viscosity rut - resistant asphalt concrete has become the key to improving pavement performance.

[0003] Traditional rut - resistant asphalt concrete mainly improves its performance by adding ordinary rut - resistant agents or increasing the viscosity of asphalt. Ordinary rut - resistant agents such as plastic and rubber additives can improve the high - temperature stability of asphalt mixtures to a certain extent, but their compatibility with asphalt is poor, which easily leads to a decline in the durability of the mixture, and problems such as aging and spalling will occur after long - term use. Simply increasing the viscosity of asphalt will deteriorate the low - temperature performance of asphalt and increase the risk of low - temperature cracking of the pavement. In addition, there are many deficiencies in the material composition and preparation process of traditional rut - resistant asphalt concrete.

[0004] In terms of materials, existing asphalt modifiers are mostly single - component and cannot meet the performance requirements of asphalt concrete in multiple aspects such as high - temperature stability, low - temperature crack resistance, and water stability at the same time. For example, although the commonly used nano - silica modifier can enhance the hardness of asphalt, due to its high surface activity, it is easy to agglomerate and is unevenly dispersed in asphalt, making it difficult to fully exert the modification effect. At the same time, the gradation design of aggregates and the selection of fillers are also relatively single, and cannot effectively improve the interlocking structure and density of asphalt mixtures.

[0005] In terms of the preparation process, traditional mixing methods are difficult to achieve the full and uniform mixing of modifiers with asphalt and aggregates, resulting in large fluctuations in the performance of asphalt concrete. Moreover, the existing preparation processes are not precise enough in controlling parameters such as temperature and time, and cannot fully stimulate the performance potential of materials, making it difficult for the comprehensive performance of asphalt concrete to reach an ideal state.

[0006] With the development of the transportation industry towards the direction of green, environmental protection and high performance, traditional rut - resistant asphalt concrete has been difficult to meet the growing transportation needs. Therefore, it is urgent to develop a new type of silica - modified high - viscosity rut - resistant asphalt concrete and its preparation method. Through innovative material formulations and preparation processes, the rut - resistant performance, durability and comprehensive road - using performance of asphalt concrete can be improved, the incidence of pavement diseases can be reduced, the service life of the pavement can be extended, and the needs of modern transportation development can be met. Summary of the Invention

[0007] (1) Technical problems to be solved Aiming at the deficiencies of the prior art, the present invention provides a silica-modified high-viscosity rutting-resistant asphalt concrete and a preparation method thereof.

[0008] (2) Technical solutions A silica-modified high-viscosity rutting-resistant asphalt concrete is made from the following raw materials in parts by weight: 40-60 parts of matrix asphalt, 8-15 parts of core-shell structure silica modifier, 5-10 parts of graphene-styrene-butadiene rubber composite high-viscosity agent, 3-8 parts of basalt-polyester hybrid fiber, 120-160 parts of multi-graded limestone aggregate, and 8-15 parts of nano-clay-mineral powder composite filler; the core-shell structure silica modifier has nano-silica as the core, and is successively coated with a polydopamine layer and a polyacrylate layer grafted with an organosilane coupling agent KH-570 on the surface; the graphene-styrene-butadiene rubber composite high-viscosity agent is prepared by in-situ polymerization of graphene oxide, styrene-butadiene rubber emulsion and silane coupling agent Si-69.

[0009] Preferably, in the core-shell structure silica modifier, the thickness of the polydopamine layer is 5-20 nm, the thickness of the polyacrylate layer is 20-50 nm, and the grafting rate of KH-570 in the polyacrylate layer is 15-30%.

[0010] Preferably, in the graphene-styrene-butadiene rubber composite high-viscosity agent, the sheet size of the graphene oxide is 1-5 μm, the oxidation degree is 30-50%, and the mass ratio of the graphene oxide in the composite high-viscosity agent is 2-8%.

[0011] Preferably, the basalt-polyester hybrid fiber is composed of basalt fiber and polyester fiber mixed in a mass ratio of 3:1-1:1, wherein the length of the basalt fiber is 6-12 mm, the diameter is 10-20 μm, the length of the polyester fiber is 3-6 mm, and the diameter is 15-30 μm.

[0012] Preferably, the multi-graded limestone aggregate is composed of four particle sizes of 4.75-9.5 mm, 2.36-4.75 mm, 0.6-2.36 mm, and 0.075-0.6 mm in a mass ratio of 40:30:20:10, and the crushing value of each level of aggregate is ≤10%.

[0013] Preferably, the nano-clay-mineral powder composite filler is composed of nano-montmorillonite and limestone powder compounded in a mass ratio of 1:5-1:10, the layer spacing of the nano-montmorillonite is 1.5-3.0 nm, and the cation exchange capacity is 80-120 mmol / 100 g.

[0014] Preferably, a preparation method of the silica-modified high-viscosity rutting-resistant asphalt concrete according to any one of the above includes the following steps: S1: Preparation of core-shell structured silica modifier. Disperse nano-silica in Tris buffer solution, add dopamine hydrochloride, and react at pH 8.5 - 9.5 and 25 - 35 °C for 12 - 24 hours to form a polydopamine coating layer; then add methyl methacrylate, butyl acrylate, KH-570 and ammonium persulfate initiator, and react at 70 - 90 °C for 6 - 12 hours to form a polyacrylate coating layer. After the reaction is completed, filter, wash and dry. S2: Preparation of graphene-butadiene rubber composite high-viscosity agent. Disperse graphene oxide in deionized water, add butadiene rubber latex and Si-69, stir and react at 60 - 80 °C for 4 - 8 hours, and then spray dry. S3: Preparation of asphalt mixture. Heat the matrix asphalt to 160 - 180 °C, add the core-shell structured silica modifier, shear and stir at a rotation speed of 2000 - 4000 r / min for 40 - 80 minutes, then add the graphene-butadiene rubber composite high-viscosity agent, and continue to shear and stir for 60 - 120 minutes. S4: Heating of aggregates. Heat the multi-graded limestone aggregates to 180 - 200 °C according to different particle sizes and then mix them. S5: Mixing. First, stir and mix the heated multi-graded limestone aggregates and the modified asphalt at 170 - 190 °C for 120 - 180 seconds, then add basalt-polyester hybrid fibers and nano-clay-mineral powder composite filler, and continue to stir and mix for 90 - 150 seconds.

[0015] Preferably, in S1, the dispersion of nano-silica is carried out by high-speed shear dispersion, the shear speed is 5000 - 10000 r / min, and the dispersion time is 30 - 60 minutes.

[0016] Preferably, in S3, the shear stirring is carried out in two stages. The first stage is to shear at 2000 - 3000 r / min for 30 - 60 minutes, and the second stage is to shear at 3000 - 4000 r / min for 10 - 20 minutes.

[0017] Preferably, in S5, the stirring and mixing are carried out in a planetary mixer, the revolution speed of the stirring paddle is 30 - 60 r / min, and the rotation speed is 60 - 120 r / min.

[0018] (III) Beneficial technical effects Compared with the existing technology, the beneficial effects of the present invention are: 1. The core-shell structured silica modifier effectively improves the dispersibility of nano-silica and its compatibility with asphalt through a unique multi-layer coating design, enhances the viscosity and high-temperature stability of asphalt, and simultaneously strengthens the anti-fatigue performance of asphalt concrete. The graphene-styrene-butadiene rubber composite high-viscosity agent combines the high strength of graphene and the high elasticity of styrene-butadiene rubber, not only increasing the viscosity of asphalt but also significantly improving the low-temperature crack resistance and toughness of asphalt concrete. The reasonable combination of basalt-polyester hybrid fibers and multi-graded limestone aggregates forms a good interlock structure, improves the density and strength of asphalt mixtures, and enhances their rutting resistance. The addition of nano-clay-powder composite fillers further optimizes the microstructure of asphalt mixtures, improving their water stability and durability.

[0019] 2. Precise dispersion and mixing processes ensure the full and uniform mixing of modifiers with asphalt and aggregates, enabling the full play of material properties. By precisely controlling parameters such as temperature and time, the performance potential of the materials is effectively stimulated, improving the stability and consistency of asphalt concrete performance.

[0020] 3. Compared with traditional rutting-resistant asphalt concrete, the product of the present invention has improved rutting resistance, enhanced low-temperature crack resistance, improved water stability, significantly enhanced durability, and an extended pavement service life. At the same time, the technology of the present invention meets the requirements of green environmental protection, reduces pavement maintenance and repair costs, and has significant economic and social benefits, providing high-performance and long-life asphalt concrete materials and preparation technology support for road construction in China. Description of the Drawings

[0021] Figure 1 is a flow chart of a method for preparing silica-modified high-viscosity rutting-resistant asphalt concrete proposed by the present invention; Figure 2 is a comparison chart of the high-temperature performance of asphalt concrete in the example and the comparative example; Figure 3 is a columnar comparison chart of the residual stability and freeze-thaw splitting strength ratio of the example and the comparative example; Figure 4 is a radar comparison chart made after unifying the dimensions of the performance data of the example and the comparative example. Detailed Embodiments

[0022] Example 1 Raw Material Preparation Matrix asphalt: Select 70# A-grade road petroleum asphalt with a penetration (25°C, 100g, 5s) of 70 (0.1mm), a softening point of 48°C, and an elongation (15°C) of 120 cm, totaling 50 parts by weight.

[0023] Core-shell structured silica modifier: During preparation, first disperse 100 g of nano-silica with a particle size of 30 nm and a specific surface area of 200 m² / g in 1000 mL of Tris buffer solution with a pH of 8.5, add 10 g of dopamine hydrochloride, and stir and react at 25 °C for 24 hours to form a polydopamine coating layer; then add 150 g of methyl methacrylate, 100 g of butyl acrylate, 20 g of KH-570, and 5 g of ammonium persulfate, and react at 70 °C for 12 hours to form a polyacrylate coating layer. After the reaction is completed, filter, wash, and dry to obtain 10 parts by weight of the modifier. The thickness of the polydopamine layer is 10 nm, the thickness of the polyacrylate layer is 30 nm, and the grafting rate of KH-570 is 20%.

[0024] Graphene-butadiene-styrene rubber composite high-viscosity agent: Disperse 5 g of graphene oxide with a sheet size of 2 μm and an oxidation degree of 40% in 500 mL of deionized water, add 50 g of butadiene-styrene rubber emulsion and 3 g of Si-69, stir and react at 60 °C for 8 hours, and then spray dry to obtain 7 parts by weight of the composite high-viscosity agent. The mass ratio of graphene oxide is 7%.

[0025] Basalt-polyester hybrid fiber: Take basalt fiber with a length of 8 mm and a diameter of 15 μm and polyester fiber with a length of 4 mm and a diameter of 20 μm according to a mass ratio of 3:1, with a total of 5 parts by weight.

[0026] Multi-graded limestone aggregate: Four particle sizes of 4.75 - 9.5 mm, 2.36 - 4.75 mm, 0.6 - 2.36 mm, and 0.075 - 0.6 mm are mixed according to a mass ratio of 40:30:20:10. The crushing value of each level of aggregate is ≤10%, with a total of 140 parts by weight.

[0027] Nano-clay-powder composite filler: Compound nano-montmorillonite with an interlayer spacing of 2.0 nm and a cation exchange capacity of 100 mmol / 100 g and limestone powder according to a mass ratio of 1:8, with a total of 10 parts by weight.

[0028] Preparation process S1: Preparation of core-shell structured silica modifier: After nano-silica reacts with dopamine hydrochloride in Tris buffer solution, it reacts with substances such as methyl methacrylate to obtain the modifier.

[0029] S2: Preparation of graphene-butadiene-styrene rubber composite high-viscosity agent: Graphene oxide reacts with butadiene-styrene rubber emulsion and Si-69 at 60 °C for 8 hours and then spray dries.

[0030] S3: Preparation of asphalt mixture: Heat the matrix asphalt to 170 °C, add the core-shell structured silica modifier, shear and stir at a speed of 2500 r / min for 60 minutes, then add the graphene-butadiene-styrene rubber composite high-viscosity agent, and continue to stir for 90 minutes.

[0031] S4: Aggregate heating: Each particle size of the multi-graded limestone aggregate is heated to 185 °C and then mixed.

[0032] S5: Mixing: First, the heated aggregate and the modified asphalt are stirred at 180 °C for 150 seconds, then fibers and fillers are added, and stirring continues for 120 seconds.

[0033] Example 2 Raw material preparation The types of each raw material are the same as those in Example 1, and some parameters are adjusted: 45 parts by weight of matrix asphalt; 8 parts by weight of the core-shell structure silica modifier, with a polydopamine layer thickness of 8 nm, a polyacrylate layer thickness of 25 nm, and a KH-570 grafting rate of 18%; 6 parts by weight of the graphene-butadiene rubber composite high-viscosity agent, with a mass ratio of graphene oxide of 6%; 4 parts by weight of basalt-polyester hybrid fiber, with a mass ratio of 1:1; 130 parts by weight of multi-graded limestone aggregate; 9 parts by weight of the nano-clay-mineral powder composite filler, with a mass ratio of 1:7.

[0034] Preparation process The preparation steps are the same as those in Example 1, and some parameters are adjusted: the reaction temperature in S1 is 28 °C; the reaction temperature in S2 is 65 °C; in S3, the rotation speed of the first stage of shear stirring is 2200 r / min for 50 minutes, and the rotation speed of the second stage is 3200 r / min for 15 minutes; the aggregate heating temperature in S4 is 180 °C; the mixing temperature in S5 is 175 °C, and the stirring times are 130 seconds and 100 seconds respectively.

[0035] Example 3 Raw material preparation 55 parts by weight of matrix asphalt; 12 parts by weight of the core-shell structure silica modifier, with a polydopamine layer thickness of 12 nm, a polyacrylate layer thickness of 35 nm, and a KH-570 grafting rate of 22%; 8 parts by weight of the graphene-butadiene rubber composite high-viscosity agent, with a mass ratio of graphene oxide of 8%; 6 parts by weight of basalt-polyester hybrid fiber, with a mass ratio of 2:1; 150 parts by weight of multi-graded limestone aggregate; 12 parts by weight of the nano-clay-mineral powder composite filler, with a mass ratio of 1:9.

[0036] Preparation process The reaction temperature in S1 is 30 °C; the reaction temperature in S2 is 70 °C; in S3, the rotation speed of the first stage of shear stirring is 2800 r / min for 70 minutes, and the rotation speed of the second stage is 3800 r / min for 18 minutes; the aggregate heating temperature in S4 is 190 °C; the mixing temperature in S5 is 185 °C, and the stirring times are 170 seconds and 130 seconds respectively.

[0037] Comparative example Using traditional rutting-resistant asphalt concrete, the raw materials are 50 parts by weight of 70# A-grade road petroleum asphalt, 5 parts by weight of ordinary rutting-resistant agent (plastic type), 5 parts by weight of basalt fiber, 140 parts by weight of limestone aggregate, and 10 parts by weight of mineral powder. During preparation, the asphalt is heated to 160 °C, the rutting-resistant agent is added and stirred evenly, and then directly stirred and mixed with the aggregate, mineral powder, and fiber heated to 170 °C.

[0038] The comparison of the low-temperature and water stability performance of the asphalt concrete in the examples and comparative examples is as follows in the table: Table 1 Sample Example 1 Example 2 Example 3 Comparative Example Low-temperature flexural failure strain (με) 3800 3600 4000 2800 Residual stability (%) 92 90 93 80 Freeze-thaw splitting strength ratio (%) 88 86 90 75 Conclusion: It can be seen from the charts that Examples 1-3 are superior to the comparative examples in terms of low-temperature flexural failure strain, residual stability, and freeze-thaw splitting strength ratio. Example 3 performs best in the three indicators, indicating that the product of the present invention has strong low-temperature crack resistance and good water stability, and can adapt to different harsh environments.

[0039] The comparison of the high-temperature performance of the asphalt concrete in the examples and comparative examples is as follows in the table: Table 2 Sample Example 1 Example 2 Example 3 Comparative Example Rutting dynamic stability (times / mm) 8500 8200 9000 5500 Softening point (°C) 58 57 60 52 Conclusion: The chart shows that the rutting dynamic stability and softening point of the three examples are significantly higher than those of the comparative examples. The rutting dynamic stability of Example 3 is the highest, and the softening point is also leading, indicating that the silica-modified high-viscosity rutting-resistant asphalt concrete of the present invention has significant advantages in high-temperature stability and can effectively resist rutting diseases.

[0040] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A silica-modified high-viscosity rutting-resistant asphalt concrete, characterized in that, It is made from the following raw materials in parts by weight: 40 - 60 parts of matrix asphalt, 8 - 15 parts of core - shell structure silica modifier, 5 - 10 parts of graphene - styrene - butadiene rubber composite high - viscosity agent, 3 - 8 parts of basalt - polyester hybrid fiber, 120 - 160 parts of multi - graded limestone aggregate, and 8 - 15 parts of nano - clay - mineral powder composite filler; The core - shell structure silica modifier has nano - silica as the core, and is successively coated with a polydopamine layer and a polyacrylate layer grafted with an organosilane coupling agent KH - 570 on the surface; The graphene - styrene - butadiene rubber composite high - viscosity agent is prepared by in - situ polymerization of graphene oxide, styrene - butadiene rubber latex and silane coupling agent Si - 69.

2. The silica-modified high-viscosity rut-resistant asphalt concrete according to claim 1, wherein It also includes that in the core - shell structure silica modifier, the thickness of the polydopamine layer is 5 - 20 nm, the thickness of the polyacrylate layer is 20 - 50 nm, and the grafting rate of KH - 570 in the polyacrylate layer is 15 - 30%.

3. The silica-modified high-viscosity rutting-resistant asphalt concrete according to claim 1, wherein It also includes that in the graphene - styrene - butadiene rubber composite high - viscosity agent, the sheet size of graphene oxide is 1 - 5 μm, the oxidation degree is 30 - 50%, and the mass ratio of graphene oxide in the composite high - viscosity agent is 2 - 8%.

4. The silica-modified high-viscosity rutting-resistant asphalt concrete according to claim 1, characterized in that The basalt - polyester hybrid fiber is composed of basalt fiber and polyester fiber in a mass ratio of 3:1 - 1:

1. Among them, the length of basalt fiber is 6 - 12 mm, the diameter is 10 - 20 μm, the length of polyester fiber is 3 - 6 mm, and the diameter is 15 - 30 μm.

5. The silica-modified high-viscosity rut-resistant asphalt concrete according to claim 1, characterized in that The multi - graded limestone aggregate is composed of four particle sizes of 4.75 - 9.5 mm, 2.36 - 4.75 mm, 0.6 - 2.36 mm, and 0.075 - 0.6 mm in a mass ratio of 40:30:20:10, and the crushing value of each level of aggregate is ≤10%.

6. The silica-modified high-viscosity rutting-resistant asphalt concrete according to claim 1, wherein, The nano - clay - mineral powder composite filler is composed of nano - montmorillonite and limestone powder in a mass ratio of 1:5 - 1:

10. The layer spacing of nano - montmorillonite is 1.5 - 3.0 nm, and the cation exchange capacity is 80 - 120 mmol / 100 g.

7. A method for preparing silica-modified high-viscosity rutting-resistant asphalt concrete according to any one of claims 1-6, characterized in that, It includes the following steps: S1: Preparation of the core - shell structure silica modifier. Disperse nano - silica in Tris buffer solution, add dopamine hydrochloride, and react at pH 8.5 - 9.5 and 25 - 35 °C for 12 - 24 hours to form a polydopamine coating layer; Then add methyl methacrylate, butyl acrylate, KH - 570 and ammonium persulfate initiator, and react at 70 - 90 °C for 6 - 12 hours to form a polyacrylate coating layer. After the reaction is completed, filter, wash, and dry. S2: Preparation of the graphene - styrene - butadiene rubber composite high - viscosity agent. Disperse graphene oxide in deionized water, add styrene - butadiene rubber latex and Si - 69, stir and react at 60 - 80 °C for 4 - 8 hours, and then spray - dry. S3: Preparation of the asphalt mixture. Heat the matrix asphalt to 160 - 180 °C, add the core - shell structure silica modifier, shear and stir at a rotation speed of 2000 - 4000 r / min for 40 - 80 minutes, then add the graphene - styrene - butadiene rubber composite high - viscosity agent, and continue to shear and stir for 60 - 120 minutes. S4: Aggregate heating, heating multi-graded limestone aggregates to 180 - 200 °C in different particle sizes respectively and then mixing them; S5: Mixing, first stirring and mixing the heated multi-graded limestone aggregates and modified asphalt at 170 - 190 °C for 120 - 180 seconds, then adding basalt-polyester hybrid fibers and nano-clay-mineral powder composite fillers, and continuing to stir and mix for 90 - 150 seconds.

8. The preparation method of the silica-modified high-viscosity rutting-resistant asphalt concrete according to claim 7, characterized in that, In the above S1, high-speed shear dispersion is used for the dispersion of nano-silica, the shear speed is 5000 - 10000 r / min, and the dispersion time is 30 - 60 minutes.

9. The preparation method of the silica-modified high-viscosity rutting-resistant asphalt concrete according to claim 7, characterized in that, In the above S3, the shear stirring is carried out in two stages. The first stage is sheared at 2000 - 3000 r / min for 30 - 60 minutes, and the second stage is sheared at 3000 - 4000 r / min for 10 - 20 minutes.

10. The preparation method of the silica-modified high-viscosity rutting-resistant asphalt concrete according to claim 7, characterized in that, In the above S5, the stirring and mixing are carried out in a planetary mixer, the revolution speed of the stirring paddle is 30 - 60 r / min, and the rotation speed is 60 - 120 r / min.

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