Ultrathin overlay asphalt mixture as well as preparation method and application thereof

Abstract

The invention discloses an ultrathin overlay asphalt mixture as well as a preparation method and application thereof, and belongs to the field of pavement maintenance. The ultrathin overlay asphalt mixture comprises the following raw materials in parts by mass: 100 parts of aggregate, 7-10 parts of SBS modified asphalt, 6-9 parts of filler and 1-3 parts of modified styrene butadiene rubber, the modified styrene butadiene rubber is grafted with a polydimethylsiloxane-trithiocarbonate chain segment; the filler comprises fly ash. Open pores in the fly ash particles can be combined with macroscopic pores of the aggregate to form a graded permeable network, so that good drainage capacity is maintained while the compactness of the overlay is improved. A hydrophobic chain segment of polydimethylsiloxane of the modified styrene-butadiene rubber can form a waterproof barrier, erosion of moisture to the asphalt mixture is reduced, water stability is effectively improved, a trithiocarbonate bond can form a new chain segment when cracks are generated, self-repairing of microcracks is achieved, fatigue damage is delayed, and the asphalt mixture has good mechanical properties. The problem that the mechanical strength and the fatigue resistance are reduced due to the improvement of the drainage performance is solved.

Description

Technical Field

[0001] This invention relates to the field of road maintenance, and in particular to an ultra-thin overlay asphalt mixture, its preparation method, and its application. Background Technology

[0002] With the gradual improvement of highway networks and the rapid increase in traffic volume, asphalt pavements frequently experience varying degrees of damage in their early stages. Ultra-thin asphalt overlay technology is a new type of pavement construction method and a type of ultra-thin asphalt concrete wearing course technology. When ordinary asphalt pavements develop problems with smoothness, waterproofing, and skid resistance after a period of use, an additional layer of asphalt mixture needs to be laid on top to improve the pavement's quality. The resulting ultra-thin asphalt overlay can provide preventative maintenance and corrective maintenance for minor defects. It can quickly improve road performance, effectively maintain pavement service levels and normal driving functions, and help extend the pavement's service life.

[0003] Drainage asphalt pavement has good surface skid resistance and noise reduction effects. Through the high porosity of the mixture structure, rainwater can quickly infiltrate and drain laterally, significantly improving the safety of driving in rainy weather. For the maintenance of this type of pavement, ultra-thin overlay asphalt mixtures also need to have good drainage performance. However, good drainage will result in larger pores inside the overlay layer, which will greatly reduce the mechanical strength and fatigue performance of the ultra-thin asphalt overlay layer, making the pavement less resistant to rutting. Moreover, under long-term loads, the overlay layer has poor impact resistance and is prone to cracking, which is not conducive to pavement maintenance and service life improvement.

[0004] Furthermore, because this type of overlay allows pavement water to enter the road, it prolongs the time the overlay is exposed to rainwater erosion, which is detrimental to extending the service life of the overlay. Therefore, there is an urgent need to obtain an ultra-thin overlay asphalt mixture with good drainage, mechanical strength, and water stability. Summary of the Invention

[0005] This invention provides an ultra-thin overlay asphalt mixture, its preparation method, and its application, which can solve the problem of the difficulty in balancing drainage and mechanical strength in existing ultra-thin permeable asphalt overlays.

[0006] In a first aspect, the present invention provides an ultra-thin overlay asphalt mixture, comprising the following raw materials in parts by weight: Collect 100 portions of materials; 7-10 parts of SBS modified bitumen; 6-9 parts of filler; 1-3 parts of modified styrene-butadiene rubber; The modified styrene-butadiene rubber is grafted with polydimethylsiloxane-trithiocarbonate segments; the filler includes fly ash.

[0007] Preferably, the aggregate includes one or a combination of two of basalt and diabase.

[0008] Preferably, the gradation ranges of aggregates and fillers are as follows: .

[0010] By adopting the above technical solution, the filler in the ultra-thin overlay asphalt mixture of the present invention includes fly ash. The fly ash particles have a well-developed microporous structure, and the open pores inside can combine with the macroporous pores of the aggregate to form a graded permeable network. Therefore, by adjusting the aggregate gradation, the density of the asphalt mixture can be improved, reducing the decrease in mechanical strength caused by high porosity. Furthermore, the microporous structure of fly ash can reduce pore blockage, maintain long-term drainage capacity, and reduce water retention time. Replacing the filler in conventional asphalt mixtures with fly ash can improve the density of the overlay layer while maintaining good drainage capacity.

[0011] Furthermore, due to the large specific surface area of ​​fly ash particles, the interfacial adhesion between aggregates and asphalt is enhanced, thereby improving the material's resistance to deformation and stability. The alkaline oxides in fly ash can also react with the carboxyl groups contained in SBS modified asphalt, improving the adhesion between asphalt mixture components and filling stress-induced cracks, dispersing stress, thereby optimizing the stress transmission path and improving the rutting resistance and impact resistance of ultra-thin asphalt overlays.

[0012] The ultra-thin overlay asphalt mixture of this invention also contains modified styrene-butadiene rubber (SBR). The SBR molecular chains contain polystyrene and butadiene. Polystyrene can form a rigid skeleton in the asphalt mixture, improving its resistance to deformation. Linear butadiene segments provide high elasticity, absorbing energy through molecular chain extension under impact loads, thereby enhancing overall mechanical strength. Furthermore, the modified SBR can form an interlocking spatial network structure in the asphalt mixture, improving its overall continuity and facilitating stress transfer.

[0013] The modified styrene-butadiene rubber (SBR) is grafted with polydimethylsiloxane-trithiocarbonate segments. The hydrophobic segments of polydimethylsiloxane can form a waterproof barrier on the aggregate surface, thereby reducing the erosion of asphalt mixtures by moisture and effectively improving the water stability of ultra-thin overlay asphalt mixtures. Furthermore, the modification treatment improves the compatibility and dispersibility between SBR and SBS-modified asphalt, inhibiting phase separation between SBR and the matrix, which would otherwise lead to a decline in material properties.

[0014] Moreover, the trithiocarbonate bond in the polydimethylsiloxane-trithiocarbonate segment is a dynamic bond that can trigger molecular chain recombination under ultraviolet light. Therefore, when the ultrathin asphalt overlay is subjected to external loads and cracks occur, it can achieve self-repair of microcracks by forming new segments. The introduction of dynamic bonds can also delay fatigue damage by dispersing load stress, thereby compensating for the decrease in mechanical strength and fatigue resistance caused by the improvement of drainage performance.

[0015] Preferably, the filler comprises fly ash and micro silica fume in a mass ratio of 1:(0 to 0.2).

[0016] More preferably, the filler comprises fly ash and micro silica fume in a mass ratio of 1:(0.05 to 0.15).

[0017] By adopting the above technical solution, fly ash particles are selected to fill the gaps between aggregates, which can improve the density of the aggregate skeleton. At the same time, since there are a large number of micropores inside the fly ash, it can act as a permeable skeleton and form a graded permeable network with the macroscopic voids formed by the aggregates. This can maintain the drainage of the asphalt mixture and achieve a balance between density and permeability.

[0018] However, fly ash contains low levels of silica and aluminum oxide, resulting in low activity of alkaline oxides and poor bonding with SBS-modified asphalt. Therefore, microsilica can be added to the filler. Microsilica contains a large amount of active silica, which can improve the dispersibility and bonding force between the filler and SBS-modified asphalt. On the other hand, the highly active silica can also undergo a hydration reaction with the alkaline oxides in fly ash to produce calcium silicate, which can form a waterproof barrier. This effectively improves the water stability of the asphalt mixture and maintains good drainage and mechanical strength.

[0019] Preferably, the raw materials for the modified styrene-butadiene rubber include solution-polymerized styrene-butadiene rubber, acrylic acid, polydimethylsiloxane-trithiocarbonate, and an initiator in a mass ratio of 1:(0.15-0.2):(0.05-0.1):(0.03-0.05).

[0020] Preferably, the initiator includes one or more combinations of benzoyl peroxide, tert-butanol peroxide, azobisisobutyronitrile, ammonium persulfate, potassium persulfate, and sodium persulfate.

[0021] Preferably, the raw materials for polydimethylsiloxane-trithiocarbonate include hydroxyl-terminated polydimethylsiloxane, trithiocarbonate and chlorinating agent in a mass ratio of 1:(0.3-0.4):(0.6-0.8).

[0022] Preferably, the chlorinating agent includes one or more combinations of oxaloyl chloride and phosphorus oxychloride.

[0023] More preferably, the hydroxyl-terminated polydimethylsiloxane is a double-hydroxyl-terminated polydimethylsiloxane.

[0024] Preferably, polydimethylsiloxane-trithiocarbonate is prepared according to the following method: A chlorinating agent is added dropwise to trithiocarbonate, and the mixture is stirred and reacted under a nitrogen atmosphere for 3-4 hours. After rotary evaporation under reduced pressure, the mixture is added to a solvent and stirred to disperse. Then, hydroxyl-terminated polydimethylsiloxane is added, and the mixture is stirred and reacted at room temperature for 12-15 hours. Finally, polydimethylsiloxane-trithiocarbonate is obtained by rotary evaporation, precipitation, and washing.

[0025] Preferably, the solvent includes any one of dichloromethane, trichloromethane, and toluene.

[0026] Preferably, the modified styrene-butadiene rubber is prepared according to the following method: Solution-polymerized styrene-butadiene rubber was added to a mixed solvent and stirred to dissolve. Acrylic acid, polydimethylsiloxane-trithiocarbonate and an initiator were then added. Under a nitrogen atmosphere, the solution temperature was raised to 60-65°C and the reaction was stirred for 3-4 hours. Finally, modified styrene-butadiene rubber was obtained through precipitation, extraction and drying.

[0027] Preferably, the mixed solvent includes a combination of two or three of cyclohexane, n-hexane, and cyclopentane.

[0028] By adopting the above technical solution, trithiocarbonate is chlorinated and then reacted with hydroxyl-terminated polydimethylsiloxane to obtain polydimethylsiloxane-trithiocarbonate. Then, using acrylic acid as a bridge, acrylic acid first undergoes free radical polymerization with solution-polymerized styrene-butadiene rubber under the action of an initiator. Acrylic acid segments are first grafted onto the surface of styrene-butadiene rubber to introduce active carboxyl groups. Then, it reacts with polydimethylsiloxane-trithiocarbonate to esterify and obtain modified styrene-butadiene rubber.

[0029] The polystyrene hard segments and butadiene soft segments in styrene-butadiene rubber (SBR) form an interwoven network structure in asphalt mixtures, which can enhance the load-dispersing ability of ultra-thin asphalt overlays and improve the rutting resistance of the overlay layer. The elastomer properties of SBR also enhance the ductility and cohesion of asphalt, allowing the asphalt mixture to maintain good elastic deformation capacity at low temperatures. Furthermore, the addition of modified SBR can composite with SBS-modified asphalt, making the adhesion between it and the aggregate more compact, forming a dense, continuous interface, reducing water penetration, improving anti-stripping ability, and increasing the water stability of the system, thus improving the residual stability of the asphalt mixture after freeze-thaw splitting. Compared to other rubber elastomers, such as chloroprene rubber, it can better improve the ductility and abrasion resistance of asphalt, and has better resistance to moisture and acids / alkalis, which is beneficial for extending pavement life and improving the mechanical strength of asphalt mixtures.

[0030] Based on the introduction of styrene-butadiene rubber (SBR), the SBR is further modified by grafting polydimethylsiloxane-trithiocarbonate onto it. On the one hand, the modification can improve the dispersibility and compatibility of SBR in asphalt mixtures. The polydimethylsiloxane segments have low surface energy, which can reduce the aggregation of polymer segments and improve the dispersion uniformity.

[0031] On the other hand, after modification, polydimethylsiloxane segments can synergistically form a double-crosslinked network with styrene-butadiene rubber segments. This three-dimensional network strengthens the mechanical strength, and the introduction of trithiocarbonate dynamic bonds allows for preferential fracture under stress or load, absorbing energy and improving the impact resistance of the resulting ultra-thin asphalt overlay. Furthermore, it allows for sufficient molecular chain expansion, repairing fatigue microcracks and maintaining the stability of the asphalt mixture's performance. The addition of polydimethylsiloxane also forms a dense water-carrying layer, reducing water penetration while draining water, thus improving the material's water stability.

[0032] Secondly, the present invention provides a method for preparing ultra-thin overlay asphalt mixture, comprising the following process steps: S1. Weigh out the corresponding mass fractions of raw materials; S2. After preheating the aggregate, add the filler and mix evenly to obtain a premix; mix SBS modified asphalt and modified styrene-butadiene rubber and heat to 180-190℃, then mix with the premix, stir evenly, and finally roll and heat set to obtain an ultra-thin overlay asphalt mixture.

[0033] Thirdly, the present invention provides an application of an ultra-thin overlay asphalt mixture, wherein the thickness of the ultra-thin overlay layer formed by the ultra-thin overlay asphalt mixture during application is 20-25 mm.

[0034] The beneficial effects of this invention are: 1. In the ultra-thin overlay asphalt mixture of the present invention, fly ash is selected as the filler. Fly ash particles have a well-developed porous structure, and the open pores inside can combine with the macroscopic pores of the aggregate to form a graded permeable network, thereby maintaining the drainage of the asphalt mixture and achieving a balance between compactness and permeability. Furthermore, it can be combined with microsilica to improve the dispersibility of the filler in SBS modified asphalt, and can also form a waterproof barrier through hydration reaction, effectively improving the water stability of the asphalt mixture.

[0035] 2. The ultra-thin overlay asphalt mixture of this invention also contains modified styrene-butadiene rubber (SBR). The modified SBR forms an interlocking spatial network structure in the asphalt mixture, improving its impact resistance and overall continuity, and facilitating stress transfer. After modification, the SBR is grafted with polydimethylsiloxane-trithiocarbonate segments. The hydrophobic segments of polydimethylsiloxane form a waterproof barrier on the aggregate surface, reducing water erosion of the asphalt mixture and effectively improving the water stability of the ultra-thin overlay asphalt mixture. The trithiocarbonate bond is a dynamic bond; when the ultra-thin asphalt overlay layer cracks under external load, it can achieve self-repair of microcracks by forming new segments. The introduction of dynamic bonds can also delay fatigue damage by dispersing load stress, thereby compensating for the decrease in mechanical strength and fatigue resistance caused by improved drainage performance. Detailed Implementation

[0036] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0037] Preparation Example

[0038] Preparation Example 1: A modified styrene-butadiene rubber was prepared according to the following method: Preparation of polydimethylsiloxane-trithiocarbonate: 6g of oxalyl chloride was added dropwise to 3g of trithiocarbonate and stirred for 3h under nitrogen atmosphere. After rotary evaporation under reduced pressure, the mixture was added to 100mL of dichloromethane and stirred to disperse. Then, 10g of dihydroxyl-terminated polydimethylsiloxane was added and stirred for 12h at room temperature. Finally, polydimethylsiloxane-trithiocarbonate was obtained by rotary evaporation, precipitation and washing.

[0039] Preparation of modified styrene-butadiene rubber: 10g of solution-polymerized styrene-butadiene rubber (grade 2305) was added to 100mL of mixed solvent (a mixture of n-hexane and cyclohexane in a volume ratio of 1:4) and stirred to dissolve. Then, 2g of acrylic acid, 1g of the polydimethylsiloxane-trithiocarbonate prepared above, and 0.5g of benzoyl peroxide were added. Under a nitrogen atmosphere, the solution temperature was raised to 60℃ and the reaction was stirred for 3h. Finally, the modified styrene-butadiene rubber was obtained by precipitation, extraction, and drying.

[0040] Preparation Example 2, a modified styrene-butadiene rubber, differs from Preparation Example 1 only in that, in the preparation process of polydimethylsiloxane-trithiocarbonate, the amount of trithiocarbonate added is 4g and the amount of oxaloyl chloride added is 8g.

[0041] Preparation Example 3, a modified styrene-butadiene rubber, differs from Preparation Example 1 only in that, in the preparation process of the modified styrene-butadiene rubber, the amount of acrylic acid added is 1.5g, the amount of polydimethylsiloxane-trithiocarbonate added is 0.5g, and the amount of benzoyl peroxide added is 0.3g.

[0042] Preparation Example 4, a modified styrene-butadiene rubber, differs from Preparation Example 1 only in that the amount of polydimethylsiloxane-trithiocarbonate added during the preparation of the modified styrene-butadiene rubber is 0.1g.

[0043] Preparation Example 5, a modified styrene-butadiene rubber, differs from Preparation Example 1 only in that the amount of polydimethylsiloxane-trithiocarbonate added during the preparation of the modified styrene-butadiene rubber is 1.5g.

[0044] Preparation Example 6, a modified styrene-butadiene rubber, differs from Preparation Example 1 only in that, in the preparation process of the modified styrene-butadiene rubber, an equal amount of dihydroxyl-terminated polydimethylsiloxane is used to replace polydimethylsiloxane-trithiocarbonate.

[0045] Example

[0046] Example 1: An ultra-thin overlay asphalt mixture was prepared according to the following process steps: S1. Weigh 100 parts of aggregate, 8 parts of SBS modified asphalt (penetration of 100-120), 7 parts of filler and 2 parts of the modified styrene-butadiene rubber prepared in Preparation Example 1; The gradation of aggregates and fillers is shown in Table 1: Table 1. Aggregate and filler gradation table for Example 1

[0047] The aggregate is diabase, and the filler is fly ash; S2. After preheating the aggregate to 160℃, add the filler and mix evenly to obtain a premix; mix SBS modified asphalt and modified styrene-butadiene rubber and heat to 185℃, then mix with the premix, stir evenly, and finally roll and heat set to obtain an ultra-thin overlay asphalt mixture.

[0048] Example 2, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the amount of SBS modified asphalt added is 7 parts, the amount of filler added is 6 parts, and the amount of modified styrene-butadiene rubber added in Preparation Example 1 is 1 part.

[0049] Example 3, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the amount of SBS modified asphalt added is 10 parts, the amount of filler added is 9 parts, and the amount of modified styrene-butadiene rubber added in Preparation Example 1 is 3 parts.

[0050] Example 4, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the modified styrene-butadiene rubber prepared in Example 1 is replaced with an equal amount of the modified styrene-butadiene rubber prepared in Example 2.

[0051] Example 5, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the modified styrene-butadiene rubber prepared in Example 1 is replaced with an equal amount of the modified styrene-butadiene rubber prepared in Example 3.

[0052] Example 6, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the filler is a mixture of fly ash and micro silica fume in a mass ratio of 1:0.1.

[0053] Example 7, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the filler is a mixture of fly ash and micro silica fume in a mass ratio of 1:0.02.

[0054] Example 8, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the filler is a mixture of fly ash and micro silica fume in a mass ratio of 1:0.3.

[0055] Example 9, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the modified styrene-butadiene rubber prepared in Example 1 is replaced with an equal amount of the modified styrene-butadiene rubber prepared in Example 4.

[0056] Example 10, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the modified styrene-butadiene rubber prepared in Example 1 is replaced with an equal amount of the modified styrene-butadiene rubber prepared in Example 5.

[0057] Comparative Example

[0058] Comparative Example 1, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the amount of modified styrene-butadiene rubber added in Preparation Example 1 is 0.5 parts.

[0059] Comparative Example 2, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the amount of modified styrene-butadiene rubber added in Preparation Example 1 is 4 parts.

[0060] Comparative Example 3, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that the modified styrene-butadiene rubber prepared in Example 1 is replaced with an equal amount of the modified styrene-butadiene rubber prepared in Example 6.

[0061] Comparative Example 4, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that an equal amount of solution-polymerized styrene-butadiene rubber is used to replace the modified styrene-butadiene rubber prepared in Preparation Example 1.

[0062] Comparative Example 5, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that an equal amount of chloroprene rubber is used to replace the modified styrene-butadiene rubber prepared in Preparation Example 1.

[0063] Comparative Example 6, an ultra-thin overlay asphalt mixture, differs from Example 1 only in that an equal amount of limestone powder is used to replace fly ash.

[0064] Performance testing

[0065] 1. Water stability test: According to the relevant record of T0729-2000 "Freeze-thaw splitting test of asphalt mixture" in JTG E20-2011 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering", the freeze-thaw splitting strength ratio of the ultra-thin asphalt mixtures obtained in the examples and comparative examples was tested.

[0066] 2. Mechanical properties: According to the relevant records of T0715-2011 "Asphalt mixture bending test" in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the low-temperature bending performance of the ultra-thin asphalt mixtures obtained in the examples and comparative examples was tested.

[0067] The results of the above experiments are shown in Table 2: Table 2 Performance Test Results

[0068] According to Table 2, and considering Examples 1, 6, and Comparative Example 6, it can be seen that the freeze-thaw splitting strength ratio and flexural tensile strength of Example 6 are increased compared to Example 1, while those of Comparative Example 6 are decreased compared to Example 1. This indicates that the mechanical strength and water stability of Example 6 are increased compared to Example 1, and the mechanical strength and water stability of Comparative Example 6 are also increased compared to Example 1. The reason for this may be that the filler added in Example 6 is a mixture of fly ash and microsilica fume. The activity of microsilica fume can improve the dispersibility and binding force of the filler in the asphalt mixture, and also help form a waterproof barrier, thus improving the water stability of the asphalt mixture. In Comparative Example 6, conventional filler was used to replace fly ash, which resulted in a decrease in drainage, and water erosion of the asphalt mixture led to a decline in performance.

[0069] Based on Examples 1, 1, and 2, it can be seen that the performance of Comparative Examples 1 and 2 is lower than that of Example 1. This may be because the amount of modified styrene-butadiene rubber added in Comparative Example 1 was reduced, and the modification effect was reduced accordingly. In Comparative Example 2, the amount of modified styrene-butadiene rubber added was increased, which led to an increase in the content of rigid segments in the asphalt mixture and an increase in the three-dimensional crosslinking density, resulting in an increase in overall brittleness, a decrease in impact resistance, and a decrease in mechanical strength.

[0070] Combining Example 1 and Comparative Example 3, it can be seen that the various properties of Comparative Example 3 are lower than those of Example 1. The reason may be that the modified styrene-butadiene rubber in Comparative Example 3 does not introduce trithiocarbonate compared to Example 1. The lack of dynamic bond introduction will lead to a decrease in the impact resistance and self-healing ability of the asphalt mixture, resulting in a decrease in mechanical strength.

[0071] Based on Examples 1, 4, and 5, it can be seen that the performance of Comparative Examples 4 and 5 is lower than that of Example 1, and the performance of Comparative Example 5 is also lower than that of Comparative Example 4. This may be because the styrene-butadiene rubber added in Comparative Example 4 was not modified, lacking the hydrophobic segment effect of polydimethylsiloxane and the introduction of dynamic bonds, resulting in decreased water stability and mechanical strength. Comparative Example 5 used chloroprene rubber, which, compared to styrene-butadiene rubber, has lower impact resistance and mechanical strength in asphalt mixtures, and because it was not modified, its water stability is also reduced.

[0072] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An ultra-thin overlay asphalt mixture characterized by, The raw materials include the following mass fractions: Aggregate 100 parts; SBS modified asphalt 7-10 parts; Filler 6-9 parts; Modified butadiene styrene rubber 1-3 parts; The modified butadiene styrene rubber is grafted with polydimethylsiloxane-trithiocarbonate segments; The filler includes fly ash.

2. The ultra-thin overlay asphalt mixture of claim 1, wherein, The filler includes fly ash and microsilica in a mass ratio of 1:(0-0.2).

3. The ultra-thin overlay asphalt mixture of claim 1, wherein, The raw materials of the modified butadiene styrene rubber include solution butadiene styrene rubber, acrylic acid, polydimethylsiloxane-trithiocarbonate and initiator in a mass ratio of 1:(0.15-0.2):(0.05-0.1):(0.03-0.05).

4. The ultra-thin overlay asphalt mixture of claim 3, wherein, The raw materials of the polydimethylsiloxane-trithiocarbonate include hydroxyl-terminated polydimethylsiloxane, trithiocarbonate and chlorinating agent in a mass ratio of 1:(0.3-0.4):(0.6-0.8).

5. The ultra-thin overlay asphalt mixture of claim 4, wherein, The polydimethylsiloxane-trithiocarbonate is prepared by the following method: The chlorinating agent is added dropwise into the trithiocarbonate, and stirred and reacted for 3-4 hours under a nitrogen atmosphere. After rotary evaporation under reduced pressure, the product is added into a solvent and stirred and dispersed. Then the hydroxyl-terminated polydimethylsiloxane is added, and stirred and reacted for 12-15 hours at room temperature. Finally, the polydimethylsiloxane-trithiocarbonate is obtained through rotary evaporation, precipitation and washing.

6. The ultra-thin overlay asphalt mixture of claim 3, wherein, The modified butadiene styrene rubber is prepared by the following method: The solution butadiene styrene rubber is added into a mixed solvent and stirred and dissolved. The acrylic acid, polydimethylsiloxane-trithiocarbonate and initiator are added. The solution temperature is increased to 60-65°C under a nitrogen atmosphere, and stirred and reacted for 3-4 hours. Finally, the modified butadiene styrene rubber is obtained through precipitation, extraction and drying.

7. The ultra-thin overlay asphalt mixture of claim 1, wherein, The aggregate includes one or a combination of basalt and diabase.

8. The ultra-thin overlay asphalt mixture of claim 1, wherein, The gradation range of the aggregate and filler is as follows: 。 9. A method of producing an ultra-thin surfaced asphalt mixture according to any one of claims 1 to 8, characterized in that, The process includes the following steps: S1. The raw materials in corresponding mass fractions are weighed; S2. The aggregate is preheated, and then the filler is added and uniformly mixed to obtain a premix. The SBS modified asphalt and the modified butadiene styrene rubber are mixed, heated to 180-190°C, and then mixed with the premix, stirred and uniformly mixed, and finally rolled and heat set to obtain the ultra-thin overlay asphalt mixture.

10. Use of the ultra-thin overlay asphalt mixture according to any one of claims 1 to 8, characterized in that, The thickness of the ultra-thin overlay layer formed by the ultra-thin overlay asphalt mixture in application is 20-25 mm.

Images