Modified asphalt concrete and preparation method and application thereof

Abstract

The application discloses modified asphalt concrete and a preparation method and application thereof, and belongs to the technical field of asphalt concrete, and is used for solving the technical problem that asphalt concrete cannot have good repairing function and durability in the prior art; wherein the preparation method of the modified asphalt concrete comprises the following steps: pouring preheated base asphalt into a stainless steel container, performing low-speed shearing, reducing temperature, slowly adding polyurethane prepolymer, reacting, adding modified basalt fiber and DBTDL, continuously reacting, and obtaining modified asphalt after the reaction is completed; heating the modified asphalt, adding preheated aggregate, stirring, adding filler, continuously stirring, and obtaining modified asphalt concrete; the prepared modified asphalt concrete has excellent self-repairing performance and durability, can effectively alleviate the situation that existing asphalt concrete is prone to cracks and has a short service life, and simultaneously reduces maintenance cost.

Description

Technical Field

[0001] This invention relates to the field of asphalt concrete technology, specifically to a modified asphalt concrete, its preparation method, and its application. Background Technology

[0002] Asphalt pavement is the mainstream structural form for highways, urban arterial roads, and bridge decks in my country. Asphalt concrete pavement is widely used in various road engineering projects due to its advantages such as high smoothness, driving comfort, low noise, and fast construction speed. However, with the continuous growth of traffic volume, the increasing proportion of heavy-duty vehicles, and the frequent occurrence of extreme weather conditions, traditional asphalt concrete pavement is prone to problems such as rutting, cracking, and spalling during use, seriously affecting the service life of the pavement and driving safety. It is known that fibers can effectively improve the mechanical and road performance of asphalt concrete, as well as its water stability, fatigue resistance, and resistance to plastic deformation. Basalt fiber and lignin fiber are commonly used due to their lower cost. Basalt fiber has high strength and thermal stability, while lignin fiber, derived from plants, has good ecological and economic benefits. Under the long-term coupled effects of heavy traffic, temperature cycling, rainwater erosion, and ultraviolet aging, asphalt mortar is prone to hardening and embrittlement. Microcracks gradually form within the mixture and continue to expand, eventually leading to defects such as network cracking, fissures, loosening, and potholes. This significantly reduces the service life of the pavement and greatly increases maintenance costs. If road cracks are not repaired in a timely and effective manner to prevent their extension, traffic pressure will further exacerbate the cracking. In addition, rainwater seeps into the subgrade through the cracks, severely reducing the strength and stability of the base layer and posing a direct threat to traffic safety.

[0003] Chinese patent CN112408862B discloses an asphalt concrete, which, by mass percentage, comprises 10-15% fly ash acid-process aluminum extraction residue, 4-6% asphalt, 50-54% crushed stone, 21-23% sand, 10-12% stone chips, and 0-3% mineral powder. However, the asphalt concrete prepared by this invention does not have a repair function during road use and cannot delay the cracking problem. Chinese patent CN106186834A discloses a recycled asphalt concrete, which includes an old asphalt mixture, a recycling agent, coarse aggregate, fine aggregate, filler, asphalt binder, and lignocellulose in a mass ratio of (25-28):(11-16):(21-25):(18-22):(8-12):(16-20):(0.2-0.4). The filler used in this invention is specifically dry ground limestone powder, which has poor interfacial compatibility with asphalt and is difficult to effectively improve the bonding strength and deformation resistance of the asphalt mortar. This makes the asphalt concrete prone to fatigue cracking under long-term load, affecting its service life. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a modified asphalt concrete, its preparation method, and its application, solving the technical problem that existing asphalt concrete cannot simultaneously possess good repair function and durability. The modified asphalt concrete prepared by this invention meets the requirements for application in road engineering, delays damage time, extends service life, and reduces maintenance costs.

[0005] To achieve the above objectives, the present invention provides a method for preparing modified asphalt concrete, comprising the following steps:

[0006] Step (1) Pour the preheated base asphalt into a stainless steel container, shear at low speed, cool down, slowly add polyurethane prepolymer, react, add modified basalt fiber and DBTDL, continue the reaction, and when the reaction is complete, obtain modified asphalt.

[0007] Step (2) Heat the modified asphalt, add the preheated aggregate, stir, add filler, and continue stirring to obtain modified asphalt concrete;

[0008] The preparation of modified basalt fibers includes the following steps:

[0009] S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are mixed evenly and reacted. After the reaction is completed, the mixture is filtered, washed, and dried to obtain epoxy-modified basalt fiber.

[0010] S2: Add epoxy-modified basalt fiber and diethanolamine to anhydrous ethanol, stir, add hydrochloric acid aqueous solution, heat to react, filter, wash, and dry to obtain modified basalt fiber.

[0011] Preferably, in step (1), the mass ratio of matrix bitumen, polyurethane prepolymer, modified basalt fiber and DBTDL is 100:(3-7):(2-4):(0.01-0.05).

[0012] Preferably, in step (1), the preparation of the polyurethane prepolymer includes the following steps:

[0013] Under a vacuum environment of -0.08MPa, HTPB after dehydration and MDI are mixed evenly at a mass ratio of 1:(0.3-0.5), heated to 75-85℃, and stirred at a constant temperature for 2-3 hours to obtain polyurethane prepolymer.

[0014] Preferably, in step (1), the preheating temperature of the base asphalt is 150-160℃ and the cooling temperature is 120-140℃.

[0015] Preferably, in step (1), the base asphalt is 70# road asphalt.

[0016] Preferably, in step (2), the aggregate includes coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder; wherein the mass ratio of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder is (30-40):(40-50):(6-10):(8-12):(1.8-2.2).

[0017] Preferably, in step (2), the mass ratio of aggregate, modified asphalt and filler is (92-96):(4.2-5.8):(0.8-1.2).

[0018] Preferably, in step (2), coarse aggregate 1 is basalt with an average diameter of 11-17 mm; coarse aggregate 2 is basalt with an average diameter of 6-11 mm; fine aggregate 1 is basalt with an average diameter of 3-6 mm; fine aggregate 2 is basalt with an average diameter of 0-3 mm; and mineral powder is basalt that has been finely ground with an average diameter of less than 0.075 mm.

[0019] Preferably, in step (2), the filler is nano-silica.

[0020] Preferably, in S1, the mass ratio of anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane is (1400-3000):(60-80):(55-95).

[0021] Preferably, in step S1, the reaction temperature is 65-85℃ and the reaction time is 4-6 hours.

[0022] Preferably, in step S2, the reaction temperature is 55-75℃ and the reaction time is 5-9h.

[0023] Preferably, in S2, the concentration of the hydrochloric acid aqueous solution is 0.01 mol / L.

[0024] Preferably, in S2, the mass ratio of epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and hydrochloric acid aqueous solution is (20-40):(100-180):(2000-4000):(10-18).

[0025] Preferably, the modified asphalt concrete is prepared using the aforementioned method.

[0026] Preferably, this describes the application of the modified asphalt concrete in the surface layer of highways and urban arterial roads.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. In this invention, basalt fibers are treated with γ-(2,3-epoxypropoxy)propyltrimethoxysilane to obtain epoxy-modified basalt fibers. These modified basalt fibers then undergo a ring-opening reaction with the imino groups in diethanolamine to obtain modified basalt fibers. The modified basalt fibers not only introduce hydroxyl-active functional groups onto their surface but also retain the high strength, high modulus, and high / low temperature resistance of basalt fibers. This invention uses a prepolymer method to prepare modified asphalt. The modified basalt fibers contain three hydroxyl groups, which can be used as chain extenders, embedding into the molecular chains of the modified asphalt and achieving better compatibility through chemical bonding. The polyurethane molecular chains in the modified asphalt contain urethane bonds and dynamic hydrogen bonds, exhibiting dynamic reversibility, enabling dynamic bond breaking and recombination. Simultaneously, the flexible soft segments undergo viscous flow, spontaneously repairing microcracks in the asphalt mastic. The microphase structure reconstruction of the polyurethane crosslinking network restores the mastic's viscosity and toughness, achieving multiple reversible self-repairs. Nano-silica can act as a physical anchor point, adsorbing and fixing the reconstructed polyurethane molecular chains after repair, ensuring that the structural stability and bonding strength of the repair mortar do not decrease. Simultaneously, the UV shielding effect of nano-silica and the resistance of the polyurethane cross-linked network in the modified asphalt to thermo-oxidative aging significantly slow down the aging process, improving durability and extending service life.

[0029] 2. In this invention, the bridging structure formed by modified basalt fibers in modified asphalt concrete effectively supports the aggregate-intercalated skeleton, preventing the collapse and blockage of permeable channels under traffic loads, thus ensuring long-term and stable drainage performance from a structural perspective. The high-viscosity cross-linked mortar formed by polyurethane only coats the aggregate surface and does not fill the skeleton voids. Simultaneously, the microscopic reinforcement and anti-sagging effect of nano-silica on the mortar jointly prevents the mortar from blocking macroscopic permeable channels. The hydrophobic groups of polyurethane form a hydrophobic film at the interface; the modified basalt fibers are embedded in the polyurethane chains, eliminating interfacial gaps; and nano-silica can fill microscopic gaps, eliminating microscopic channels for water intrusion. The synergistic effect of these three factors ensures the water stability of the modified asphalt concrete. The cross-linked network formed by polyurethane in modified asphalt significantly improves the high-temperature stiffness of asphalt mortar; the rigid skeleton composed of modified basalt fiber effectively restricts the relative slippage between aggregate and mortar at high temperatures, which is beneficial to deformation resistance; nano-silica produces a nano-reinforcing effect in mortar, which improves the high-temperature modulus of mortar. All these factors combined make modified asphalt concrete more resistant to high temperatures, more resistant to deformation, and more stable in structure.

[0030] 3. The modified asphalt concrete material prepared by this invention balances the common problem of drainage and strength contradiction in existing permeable asphalt concrete, and possesses excellent water stability, high-temperature performance, and self-healing properties. It significantly reduces the probability of fatigue cracking in asphalt concrete under long-term loads, significantly enhances the water stability of the modified asphalt concrete, effectively inhibits loosening and spalling caused by rainwater erosion, and extends the service life of the pavement. Furthermore, the preparation method of this invention has high raw material utilization, reduces energy consumption and costs in the production process, and the prepared modified asphalt concrete exhibits excellent performance, meeting the diverse needs of road engineering projects, delaying pavement damage, reducing the frequency and cost of subsequent maintenance, and possessing significant economic and application value. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment provides a method for preparing modified asphalt concrete, including the following steps:

[0034] Step (1) Pour the preheated base asphalt to 150°C into a stainless steel container, shear at 900 r / min for 10 min, cool down to 120°C, slowly and uniformly add polyurethane prepolymer, react at 120°C for 30 min, add modified basalt fiber and DBTDL, continue to keep warm for 12 h, the reaction ends, and the modified asphalt is obtained.

[0035] The mass ratio of the matrix bitumen, polyurethane prepolymer, modified basalt fiber and DBTDL is 100:3:2:0.01.

[0036] Step (2) Heat the modified asphalt to 150°C, add the aggregate preheated to 160°C, stir at 30 r / min for 90 s, add nano silica, continue stirring at 30 r / min for 60 s, stir until the mixture is evenly coated, and obtain modified asphalt concrete.

[0037] The mass ratio of aggregate, modified asphalt, and nano-silica is 92:4.2:0.8.

[0038] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 30:40:6:8:1.8.

[0039] The preparation of modified basalt fibers includes the following steps:

[0040] S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed evenly in a mass ratio of 1400:60:55 and reacted at 65℃ for 6 hours. After the reaction was completed, the mixture was filtered, washed three times with anhydrous ethanol, and dried at 80℃ for 10 hours to obtain epoxy-modified basalt fiber.

[0041] S2: Epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and 0.01 mol / L hydrochloric acid aqueous solution are mixed in a mass ratio of 20:100:2000:10 and reacted at 55℃ for 9 h. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried at 85℃ for 14 h to obtain modified basalt fiber.

[0042] Example 2

[0043] This embodiment provides a method for preparing modified asphalt concrete, including the following steps:

[0044] Step (1) Pour the preheated base asphalt to 153℃ into a stainless steel container, shear at 800r / min for 9min, cool down to 125℃, slowly and uniformly add polyurethane prepolymer, react at 125℃ for 28min, add modified basalt fiber and DBTDL, continue to keep warm for 11.5h, the reaction ends, and modified asphalt is obtained.

[0045] The mass ratio of the matrix asphalt, polyurethane prepolymer, modified basalt fiber, and DBTDL is 100:4:2.5:0.02.

[0046] Step (2) Heat the modified asphalt to 153°C, add the aggregate preheated to 165°C, stir at 35 r / min for 82 s, add nano silica, and continue stirring at 45 r / min for 52 s until the mixture is evenly coated to obtain modified asphalt concrete.

[0047] The mass ratio of aggregate, modified asphalt, and nano-silica is 93:4.6:0.9.

[0048] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 32:42:7:9:1.9.

[0049] The preparation of modified basalt fibers includes the following steps:

[0050] S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed evenly at a mass ratio of 1800:65:65 and reacted at 70℃ for 5.5 h. After the reaction was completed, the mixture was filtered, washed three times with anhydrous ethanol, and dried at 85℃ for 9.5 h to obtain epoxy-modified basalt fiber.

[0051] S2: Epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and 0.01 mol / L hydrochloric acid aqueous solution are mixed in a mass ratio of 25:120:2500:12 and reacted at 60℃ for 8 hours. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried at 87℃ for 13.5 hours to obtain modified basalt fiber.

[0052] Example 3

[0053] This embodiment provides a method for preparing modified asphalt concrete, including the following steps:

[0054] Step (1) Pour the preheated base asphalt to 155℃ into a stainless steel container, shear at 700r / min for 7min, cool down to 130℃, slowly and uniformly add polyurethane prepolymer, react at 130℃ for 25min, add modified basalt fiber and DBTDL, continue to keep warm for 11h, the reaction ends, and modified asphalt is obtained.

[0055] The mass ratio of the matrix asphalt, polyurethane prepolymer, modified basalt fiber and DBTDL is 100:5:3:0.03.

[0056] Step (2) Heat the modified asphalt to 155°C, add the aggregate preheated to 170°C, stir at 40 r / min for 75 s, add nano silica, continue stirring at 40 r / min for 45 s, stir until the mixture is evenly coated, and obtain modified asphalt concrete.

[0057] The mass ratio of aggregate, modified asphalt, and nano-silica is 94:5:1.

[0058] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 35:45:8:10:2.

[0059] The preparation of modified basalt fibers includes the following steps:

[0060] S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed evenly in a mass ratio of 2200:70:75 and reacted at 75℃ for 5 hours. After the reaction was completed, the mixture was filtered, washed three times with anhydrous ethanol, and dried at 90℃ for 9 hours to obtain epoxy-modified basalt fiber.

[0061] S2: Epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and 0.01 mol / L hydrochloric acid aqueous solution are mixed in a mass ratio of 30:140:3000:14 and reacted at 65℃ for 7 h. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried at 90℃ for 13 h to obtain modified basalt fiber.

[0062] Example 4

[0063] This embodiment provides a method for preparing modified asphalt concrete, including the following steps:

[0064] Step (1) Pour the preheated base asphalt to 157°C into a stainless steel container, shear at 600 r / min for 6 min, cool down to 135°C, slowly and uniformly add polyurethane prepolymer, react at 135°C for 22 min, add modified basalt fiber and DBTDL, continue to keep warm for 10.5 h, the reaction ends, and modified asphalt is obtained.

[0065] The mass ratio of the matrix asphalt, polyurethane prepolymer, modified basalt fiber, and DBTDL is 100:6:3.5:0.04.

[0066] Step (2) Heat the modified asphalt to 157°C, add the aggregate preheated to 175°C, stir at 45 r / min for 68 s, add nano silica, and continue stirring at 35 r / min for 37 s until the mixture is evenly coated to obtain modified asphalt concrete.

[0067] The mass ratio of aggregate, modified asphalt, and nano-silica is 95:5.4:1.1.

[0068] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 37:47:9:11:2.1.

[0069] The preparation of modified basalt fibers includes the following steps:

[0070] S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed evenly in a mass ratio of 2600:75:85 and reacted at 80℃ for 4.5 h. After the reaction was completed, the mixture was filtered, washed three times with anhydrous ethanol, and dried at 95℃ for 8.5 h to obtain epoxy-modified basalt fiber.

[0071] S2: Epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and 0.01 mol / L hydrochloric acid aqueous solution are mixed in a mass ratio of 35:160:3500:16 and reacted at 70℃ for 6 h. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried at 92℃ for 12.5 h to obtain modified basalt fiber.

[0072] Example 5

[0073] This embodiment provides a method for preparing modified asphalt concrete, including the following steps:

[0074] Step (1) Pour the preheated base asphalt to 160℃ into a stainless steel container, shear at 500r / min for 5min, cool down to 140℃, slowly and uniformly add polyurethane prepolymer, react at 140℃ for 20min, add modified basalt fiber and DBTDL, continue to keep warm for 10h, the reaction ends, and the modified asphalt is obtained.

[0075] The mass ratio of the matrix bitumen, polyurethane prepolymer, modified basalt fiber and DBTDL is 100:7:4:0.05.

[0076] Step (2) Heat the modified asphalt to 160°C, add the aggregate preheated to 180°C, stir at 50 r / min for 60 s, add nano silica, and continue stirring at 30 r / min for 30 s until the mixture is evenly coated to obtain modified asphalt concrete.

[0077] The mass ratio of aggregate, modified asphalt, and nano-silica is 96:5.8:1.2.

[0078] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 40:50:10:12:2.2.

[0079] The preparation of modified basalt fibers includes the following steps:

[0080] S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed evenly in a mass ratio of 3000:80:95 and reacted at 85℃ for 4 hours. After the reaction was completed, the mixture was filtered, washed three times with anhydrous ethanol, and dried at 100℃ for 8 hours to obtain epoxy-modified basalt fiber.

[0081] S2: Epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and 0.01 mol / L hydrochloric acid aqueous solution are mixed in a mass ratio of 40:180:4000:18 and reacted at 75℃ for 5 h. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried at 95℃ for 12 h to obtain modified basalt fiber.

[0082] Example 6

[0083] This embodiment provides a method for preparing a polyurethane prepolymer, including the following steps:

[0084] Under a vacuum environment of -0.08 MPa, HTPB (hydroxyl-terminated polybutadiene) after water removal and MDI (diphenylmethane diisocyanate) were mixed evenly at a mass ratio of 1:0.5, and the mixture was heated to 75°C and reacted at a constant temperature for 3 hours to obtain a polyurethane prepolymer.

[0085] Comparative Example 1

[0086] This comparative example provides a method for preparing modified asphalt concrete, including the following steps:

[0087] Step (1) Pour the preheated base asphalt to 150°C into a stainless steel container, shear at 900 r / min for 10 min, cool down to 120°C, slowly and uniformly add polyurethane prepolymer, react at 120°C for 30 min, add modified basalt fiber and DBTDL, continue to keep warm for 12 h, the reaction ends, and the modified asphalt is obtained.

[0088] The mass ratio of the matrix bitumen, polyurethane prepolymer, modified basalt fiber and DBTDL is 100:3:2:0.01.

[0089] Step (2) Heat the modified asphalt to 150°C, add the aggregate preheated to 160°C, and stir at a speed of 30 r / min for 90 s until the mixture is evenly coated to obtain modified asphalt concrete.

[0090] The mass ratio of aggregate to modified asphalt is 92.8:4.2.

[0091] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 30:40:6:8:1.8.

[0092] The preparation of modified basalt fibers includes the following steps:

[0093] S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed evenly in a mass ratio of 1400:60:55 and reacted at 65℃ for 6 hours. After the reaction was completed, the mixture was filtered, washed three times with anhydrous ethanol, and dried at 80℃ for 10 hours to obtain epoxy-modified basalt fiber.

[0094] S2: Epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and 0.01 mol / L hydrochloric acid aqueous solution are mixed in a mass ratio of 20:100:2000:10 and reacted at 55℃ for 9 h. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried at 85℃ for 14 h to obtain modified basalt fiber.

[0095] Comparative Example 2

[0096] This comparative example provides a method for preparing modified asphalt concrete, including the following steps:

[0097] Step (1) Pour the preheated base asphalt to 150°C into a stainless steel container, shear it at 900 r / min for 10 min, cool it down to 120°C, slowly and uniformly add polyurethane prepolymer, keep it at 120°C for 30 min, add diethanolamine and DBTDL, continue to keep it at the temperature for 12 h, the reaction ends, and the modified asphalt is obtained.

[0098] The mass ratio of the base bitumen, polyurethane prepolymer, diethanolamine, and DBTDL is 100:3:2:0.01.

[0099] Step (2) Heat the modified asphalt to 150°C, add the aggregate preheated to 160°C, stir at 30 r / min for 90 s, add basalt fiber, continue stirring at 30 r / min for 60 s, stir until the mixture is evenly coated, and obtain modified asphalt concrete.

[0100] The mass ratio of aggregate, modified asphalt, and basalt fiber is 92:4.2:0.8.

[0101] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 30:40:6:8:1.8.

[0102] Comparative Example 3

[0103] This comparative example provides a method for preparing modified asphalt concrete, including the following steps:

[0104] SBS modified asphalt is heated to 150°C, and aggregate preheated to 160°C is added. The mixture is stirred at 30 r / min for 90 seconds, basalt fiber is added, and the mixture is stirred at 30 r / min for 60 seconds until the mixture is evenly coated, thus obtaining modified asphalt concrete.

[0105] The mass ratio of aggregate, SBS modified asphalt, and basalt fiber is 92:4.2:0.8.

[0106] The aggregate consists of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder in a mass ratio of 30:40:6:8:1.8.

[0107] The polyurethane prepolymers used in Examples 1-5 and Comparative Examples 1-2 of the present invention are all polyurethane prepolymers prepared in Example 6.

[0108] In the embodiments and comparative examples of the present invention, coarse aggregate 1 is basalt with an average diameter of 11-17 mm, coarse aggregate 2 is basalt with an average diameter of 6-11 mm, fine aggregate 1 is basalt with an average diameter of 3-6 mm, fine aggregate 2 is basalt with an average diameter of 0-3 mm, mineral powder is basalt that has been finely ground with an average diameter of less than 0.075 mm, and basalt fiber is basalt fiber particles with a nanoscale particle size of 10-100 nm.

[0109] In this invention, the base asphalt is 70# road asphalt from Hengshui Zehao Rubber & Chemical Co., Ltd.; HTPB is hydroxyl-terminated polybutadiene from Shenzhen Hongyuan Chemical New Material Technology Co., Ltd.; MDI is diphenylmethane diisocyanate from Wanhua Chemical Group Co., Ltd.; nano silica is from Shanghai Aladdin Biochemical Technology Co., Ltd., with a particle size of 30nm and product number: S490064; diethanolamine is from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS number: 111-42-2; basalt fiber is from Jiangxi Shuobang New Material Technology Co., Ltd., with a particle size of 12nm; and all others are commercially available products.

[0110] Performance testing:

[0111] (1) The modified asphalt concrete prepared in Examples 1-5 and Comparative Examples 1-3 were tested according to the test methods specified in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering"; the void ratio of the modified asphalt concrete was determined according to T 0709-2011; rutting tests were conducted according to T 0719-2011, with a test temperature of 60℃ and a wheel pressure of 0.7MPa, and the specimens used were rutting slab specimens with dimensions of 300mm x 300mm x 50mm; Marshall stability tests were conducted according to T 0709-2011, with the stability measured after 0.5h of heat treatment in a water bath at 60℃, and the stability of the water-immersed Marshall specimens was measured after 48h of heat treatment in a constant temperature water bath, and the residual stability after immersion was calculated. The tests were repeated 3 times and the average value was recorded; T The freeze-thaw splitting test disclosed in 0729-2000 was used to test the water stability of modified asphalt concrete, and the freeze-thaw splitting tensile strength ratio was used as an index to evaluate its resistance to water damage. The modified asphalt concrete prepared in Examples 1-5 and Comparative Examples 1-3 was used to prepare rutted slabs, and small beam specimens with dimensions of 250mm×40mm×40mm were cut and subjected to bending and tensile fatigue tests to determine the number of loads corresponding to failure. The specific test results are shown in Table 1.

[0112] Table 1

[0113] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Porosity (%) 21.3 20.9 20.6 20.7 20.8 21.8 22 23.8 Dynamic stability of wheel rutting test (cycles / mm) 6532 6584 6638 6601 6569 6325 6214 5536 Stability after immersion in water for 48 hours (kN) 6.72 6.83 6.91 6.88 6.85 6.57 6.38 5.43 Water immersion residual stability (%) 91.6 92.4 93.2 92.8 92.6 91 90.5 86 Freeze-thaw splitting tensile strength ratio (%) 96.8 97.5 98.3 98.1 97.8 92.4 88.1 80 <![CDATA[Number of load actions (10 6 times)]]> 1.12 1.24 1.39 1.36 1.31 1.01 0.98 0.6

[0114] As can be seen from the test results in Table 1, the modified asphalt concrete in Examples 1-5 better balanced drainage and water stability, and exhibited superior high-temperature stability and low-temperature crack resistance. Specifically, the stability after 48 hours of immersion in water in Examples 1-5 was all above 6.57 kN, and the residual stability after immersion remained at 90.5% or higher, indicating that it could maintain high structural strength even under long-term water exposure. The dynamic splitting tensile strength ratio of the modified asphalt concrete in Examples 1-5 all exceeded 92.4%, with Example 3 reaching 98.3%, far higher than the comparative example, demonstrating excellent synergistic improvement in low-temperature crack resistance and water stability. The number of load applications in Examples 1-5 were all above 10. 6 The fact that it can withstand repeated loads multiple times indicates that it has a stronger ability to resist repeated loads and better durability. Nano-silica not only fills voids but also significantly increases the high-temperature viscosity and elastic modulus of asphalt mortar, making the asphalt more difficult to flow at high temperatures. This directly enhances the modified asphalt concrete's resistance to permanent deformation. If it is lacking, the performance decreases; therefore, the dynamic stability value of Comparative Example 1 is lower than that of Example 1. Basalt fiber plays a role in three-dimensional reinforcement and crack bridging in the mixture, effectively dispersing and transferring load stress and constraining the displacement of aggregates, thereby significantly improving high-temperature rutting resistance. If it is lacking, the reinforcement effect disappears, and the dynamic stability decreases; therefore, the dynamic stability value of Comparative Example 2 is lower than that of Comparative Example 1. Meanwhile, the modified asphalt in Comparative Example 2 contains polyurethane segments, which have better high-temperature resistance than SBS. Furthermore, the dynamic stability of Comparative Example 3 is lower than that of Comparative Example 2.

[0115] (2) Pull-out tests were conducted on the modified asphalt in Example 1 and Comparative Examples 1-2, and the SBS modified asphalt in Comparative Example 3. Granite with dimensions of 100 mm x 100 mm x 10 mm was selected as the substrate, sanded until the surface was rough, wiped clean with anhydrous ethanol and dried. The modified asphalt in Example 1 and Comparative Examples 1-2 and the SBS modified asphalt in Comparative Example 3 were heated to a fluid state and uniformly coated on the substrate with a thickness of 1 mm. After cooling to room temperature, the substrate was demolded to obtain standard asphalt film specimens, which were recorded as samples 1-4 and their initial strength was measured. Samples 1-4 were repeatedly pulled out at the same temperature until they were completely destroyed, so that the asphalt film was separated from the substrate. The destroyed specimens were placed in a constant temperature chamber at 50°C for 48 h to allow the asphalt film to self-heal, and the tensile strength after repair was measured. The repair rate was calculated. Each group was repeated 3 times and the average value was recorded. The pull-out rate was 1 mm / min. The specific test results are shown in Table 2.

[0116] Table 2

[0117] Test Project Sample 1 Sample 2 Sample 3 Sample 4 Repair rate (%) 90.2 86.4 80.6 32.1

[0118] As shown in Table 2, the modified asphalt prepared by this invention exhibits good repair performance. The dynamically reversible chemical bonds contained in the polyurethane segments of the modified asphalt can break and recombine under temperature, and this dynamic behavior endows the modified asphalt with excellent self-healing ability; the repair effect is better at higher temperatures. Comparative Example 1 lacks the basalt fiber insertion into the polyurethane segments compared to Example 1, resulting in weaker reinforcement and crack bridging effects and reduced repair ability. Compared to Comparative Example 1, Comparative Example 2 uses unmodified basalt fibers, leading to weaker interfacial bonding with the polyurethane segments, resulting in decreased reinforcement and crack bridging capabilities, and affecting the efficiency of breaking and recombination of the dynamically reversible chemical bonds in the polyurethane segments, thus making the self-healing performance of Comparative Example 2 lower than that of Comparative Example 1. The SBS modified asphalt used in Comparative Example 3 does not contain dynamically reversible chemical bond structures; therefore, the repair ability of the SBS modified asphalt in Comparative Example 3 is lower than that of the modified asphalt in Comparative Example 2.

[0119] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0120] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0121] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing modified asphalt concrete, characterized in that, Includes the following steps: Step (1) Pour the preheated base asphalt into a stainless steel container, shear at low speed, cool down, slowly add polyurethane prepolymer, react, add modified basalt fiber and DBTDL, continue the reaction, and when the reaction is complete, obtain modified asphalt. In step (1), the preparation of the polyurethane prepolymer includes the following steps: Under a vacuum environment of -0.08MPa, HTPB after dehydration and MDI are mixed evenly at a mass ratio of 1:(0.3-0.5), heated to 75-85℃, and stirred at a constant temperature for 2-3 hours to obtain polyurethane prepolymer. Step (2) Heat the modified asphalt, add the preheated aggregate, stir, add filler, and continue stirring to obtain modified asphalt concrete; In step (2), the filler is nano-silica; The preparation of modified basalt fibers includes the following steps: S1: Anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are mixed evenly and reacted. After the reaction is completed, the mixture is filtered, washed, and dried to obtain epoxy-modified basalt fiber. S2: Add epoxy-modified basalt fiber and diethanolamine to anhydrous ethanol, stir, add hydrochloric acid aqueous solution, heat to react, filter, wash, and dry to obtain modified basalt fiber.

2. The method for preparing modified asphalt concrete according to claim 1, characterized in that, In step (1), the mass ratio of matrix asphalt, polyurethane prepolymer, modified basalt fiber and DBTDL is 100:(3-7):(2-4):(0.01-0.05).

3. The method for preparing modified asphalt concrete according to claim 1, characterized in that, In step (1), the preheating temperature of the base asphalt is 150-160℃; the cooling temperature is 120-140℃.

4. The method for preparing modified asphalt concrete according to claim 1, characterized in that, In step (2), the aggregate includes coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder; wherein the mass ratio of coarse aggregate 1, coarse aggregate 2, fine aggregate 1, fine aggregate 2 and mineral powder is (30-40):(40-50):(6-10):(8-12):(1.8-2.2).

5. The method for preparing modified asphalt concrete according to claim 1, characterized in that, In step (2), the mass ratio of aggregate, modified asphalt and filler is (92-96):(4.2-5.8):(0.8-1.2).

6. The method for preparing modified asphalt concrete according to claim 1, characterized in that, In S1, the mass ratio of anhydrous ethanol, basalt fiber, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane is (1400-3000):(60-80):(55-95).

7. The method for preparing modified asphalt concrete according to claim 1, characterized in that, In S2, the mass ratio of epoxy-modified basalt fiber, diethanolamine, anhydrous ethanol and hydrochloric acid aqueous solution is (20-40):(100-180):(2000-4000):(10-18).

8. A modified asphalt concrete prepared by the method for preparing modified asphalt concrete according to any one of claims 1-7.

9. An application of the modified asphalt concrete according to claim 8 in the surface layer of highways and urban main roads.