Rock asphalt composite modified asphalt and preparation method thereof

Abstract

The invention belongs to the technical field of road engineering, and discloses rock asphalt composite modified asphalt and a preparation method thereof. The composite modified asphalt is prepared from the following raw materials: matrix asphalt, rock asphalt, SBS, rubber powder, low-density polyethylene, a main stabilizer, a rock asphalt surface modifier, hydrogen peroxide, a hydrogen peroxide catalyst, an auxiliary stabilizer, a compatilizer, an antioxidant, a rubber activator, a PE-LD grafting monomer, a PE-LD initiator and a rubber desulfurizer. The preparation process comprises the following two steps: preparation of modified PE-LD, preparation of modified rubber powder, pretreatment of raw materials for rock asphalt surface treatment, and preparation of the composite modified asphalt. Through the synergistic effect of the rock asphalt, the SBS, the rubber powder, the PE-LD and other components, the compatibility of all the components and matrix asphalt is remarkably improved, the problem of segregation when a large amount of rock asphalt is doped is solved, meanwhile, the high and low temperature performance, the rutting resistance and the mechanical stability of the composite modified asphalt are greatly optimized, the production cost is reduced, the process is reasonable, industrialization is easy, and the preparation method is suitable for industrial production. The method is suitable for road engineering.

Description

TECHNICAL FIELD

[0001] The present application relates to road engineering materials. BACKGROUND

[0002] In road engineering, asphalt as the core cementing material, its performance directly determines the service life and driving safety of the pavement. Buton rock asphalt is a kind of light brown fine-grained solid material formed by nature for billions of years, mainly composed of natural asphalt and limestone minerals, and has excellent anti-aging ability. The alkaline minerals in it can be used as a high-alkaline activator to significantly enhance the adhesion of asphalt and aggregate and the high-temperature rutting resistance of asphalt mixture, so it has important application potential in the field of asphalt modification.

[0003] However, there are two key problems in the use of Buton rock asphalt in the prior art: one is the segregation phenomenon. When a large amount of Buton rock asphalt is added to the base asphalt, due to the poor interfacial compatibility of rock asphalt and base asphalt, the components are prone to stratification, which seriously weakens the performance improvement effect of rock asphalt on base asphalt. The second is the single performance. The addition of rock asphalt alone cannot meet the comprehensive requirements of modern roads for high-performance asphalt (such as low-temperature crack resistance, fatigue life, long-term stability, etc.). Therefore, it is an urgent need in the field of road engineering to develop a preparation method of rock asphalt composite modified asphalt that can solve the segregation problem and balance the high-temperature rutting resistance, low-temperature crack resistance and mechanical stability. SUMMARY

[0004] One of the technical problems solved by the present application is to provide a rock asphalt composite modified asphalt. Through the synergistic effect of rock asphalt, SBS, rubber powder, PE-LD and other components, the compatibility of each component with base asphalt is significantly improved, the segregation problem when a large amount of rock asphalt is added is solved, and the high and low temperature performance, rutting resistance and mechanical stability of the composite modified asphalt are greatly optimized.

[0005] The present application is thus able to solve one of the above technical problems:

[0006] A rock asphalt composite modified asphalt is composed of the following raw materials by weight: base asphalt 50-70 parts, rock asphalt 5-20 parts, SBS 4-6 parts, rubber powder 8-12 parts, low-density polyethylene 5-8 parts, main stabilizer 1-3 parts, rock asphalt surface modifier 0.5-1.5 parts, hydrogen peroxide 8-12 parts, hydrogen peroxide catalyst 0.1-0.3 parts, auxiliary stabilizer 0.3-0.8 parts, compatibility agent 1-3 parts, antioxidant 0.2-0.5 parts, rubber activator 0.5-1 parts, PE-LD grafting monomer 1-2 parts, PE-LD initiator 0.1-0.3 parts, and rubber devulcanizing agent 0.3-0.6 parts.

[0007] Further, the base asphalt is 70# base asphalt.

[0008] Further, the ash content of the rock asphalt is not more than 75%.

[0009] Further, the SBS is linear SBS, and the molecular weight is 100-300 thousand.

[0010] Further, the rubber powder is waste tire rubber powder, and the particle size is 40-80 mesh.

[0011] Further, the mass fraction of the hydrogen peroxide is 1%-5%.

[0012] Further, the hydrogen peroxide catalyst is CuFeO2, FeSO4 or catalase.

[0013] Further, the main stabilizer is sulfur, the rock asphalt surface modifier is a silane coupling agent, the auxiliary stabilizer is calcium stearate, the compatibilizer is maleic anhydride grafted polyethylene (PE-g-MAH), the antioxidant is a hindered phenolic antioxidant, the rubber activator is a composite system of zinc oxide and stearic acid, and the mass ratio of the two is 1:1, the PE-LD grafting monomer is maleic anhydride (MAH), the PE-LD initiator is dicumyl peroxide (DCP), and the rubber devulcanizing agent is dibenzoyl disulfide (DBD).

[0014] The second technical problem to be solved by the present application is to provide a preparation method of rock asphalt composite modified asphalt, which significantly improves the compatibility of each component with base asphalt through the synergistic effect of rock asphalt, SBS, rubber powder, PE-LD and other components, raw material pretreatment (including modified PE-LD preparation, modified rubber powder preparation, rock asphalt surface treatment) and composite modified asphalt preparation steps, solves the segregation problem when a large amount of rock asphalt is added, significantly optimizes the high and low temperature performance, anti-rutting ability and mechanical stability of the composite modified asphalt, reduces the production cost, and the process is reasonable and easy to industrialize, and is suitable for the field of road engineering.

[0015] The present application solves the second technical problem as follows:

[0016] A preparation method of rock asphalt composite modified asphalt, comprising the following steps:

[0017] (1) Raw material pretreatment:

[0018] a. Preparation of modified PE-LD: Low-density polyethylene (PE-LD) is added to a twin-screw extruder and heated to 160-180℃ to melt it. Then, PE-LD grafting monomer and PE-LD initiator are added, wherein the mass ratio of PE-LD, PE-LD grafting monomer and PE-LD initiator is 100:(4~6):(0.6~1.1). The melt grafting reaction is carried out at a screw speed of 200-250 r / min for 8-10 minutes to obtain grafted modified PE-LD. The grafted modified PE-LD is then pulverized to a particle size of 2-3 mm for later use.

[0019] b. Preparation of modified rubber powder: First, place the rubber powder in 1%-5% hydrogen peroxide, wherein the catalyst of the hydrogen peroxide is CuFeO2, FeSO4 or catalase, and react at 30-40℃ for 2-3 hours to obtain oxidized rubber powder; mix the oxidized rubber powder with rubber activator and rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 100:4:2, and place it in a mixer, and mix at 150-160℃ and 60-80 r / min for 20-30 minutes, while simultaneously purging with nitrogen gas for protection, to complete the desulfurization and activation modification; then dry the modified rubber powder at 100-120℃ for 2-3 hours for later use;

[0020] c. Rock asphalt treatment: Crush the rock asphalt to a particle size of no more than 5 mm, add the rock asphalt surface modifier, stir for 10-15 minutes at a stirring speed of 200-300 r / min to complete the surface modification;

[0021] (2) Preparation of composite modified asphalt: Heat the base asphalt to 155-175℃, add the surface-modified rock asphalt, stir for 35-45 minutes to dissolve it, keep the temperature at 165-185℃, and stir at 2000-4000 r / min; then add SBS, main stabilizer and auxiliary stabilizer, continue stirring for 50-60 minutes, keep the temperature at 185-195℃, and stir at 4000-5000 r / min; add compatibilizer and modified PE-LD, stir for 15-20 minutes, keep the temperature unchanged; finally add modified rubber powder and antioxidant, stir for 30-40 minutes, keep the temperature at 185-205℃, and stir at 3500-4500 r / min to obtain composite modified asphalt.

[0022] The present invention has the following advantages:

[0023] This invention significantly improves the compatibility of each component with the base asphalt through the synergistic effect of rock asphalt, SBS, rubber powder, PE-LD and other components, solves the segregation problem when rock asphalt is added in large quantities, and greatly optimizes the high and low temperature performance, rutting resistance and mechanical stability of the composite modified asphalt, while reducing production costs. The process is reasonable and easy to industrialize, and it is suitable for the field of road engineering.

[0024] Furthermore, this invention optimizes raw material properties through a three-step pretreatment process, fundamentally improving compatibility:

[0025] 1. Preparation of modified PE-LD: PE-LD is a non-polar polymer with poor compatibility with asphalt. By introducing maleic anhydride (MAH) polar groups through melt grafting (160-180℃, 200-250r / min), PE-LD-g-MAH is formed. Its carboxyl groups can form hydrogen bonds with the polar components of asphalt (asphaltite, resin), which significantly improves compatibility.

[0026] 2. Preparation of modified rubber powder: First, carboxyl / hydroxyl groups are introduced on the surface of the rubber powder by oxidation with hydrogen peroxide (30-40℃, 2-3h) (polarization). Then, the rubber crosslinking bonds are broken by desulfurization activation (150-160℃, nitrogen protection). At the same time, the rubber activator stabilizes the molecular chain, so that the rubber powder is transformed from "rigid particles" into "dispersible elastomer" to avoid agglomeration.

[0027] 3. Rock asphalt surface treatment: Silane coupling agents form an "inorganic-organic bridge" on the surface of rock asphalt minerals through "hydrolysis and condensation" (silicon-oxygen bonds connect minerals, and organic functional groups bind asphalt), eliminating interfacial tension and solving the segregation problem.

Detailed Implementation Methods

[0028] This invention relates to a rock asphalt composite modified asphalt, which is composed of the following raw materials in parts by weight: 50-70 parts base asphalt, 5-20 parts rock asphalt, 4-6 parts SBS, 8-12 parts rubber powder, 5-8 parts low-density polyethylene, 1-3 parts main stabilizer, 0.5-1.5 parts rock asphalt surface modifier, 8-12 parts hydrogen peroxide, 0.1-0.3 parts hydrogen peroxide catalyst, 0.3-0.8 parts auxiliary stabilizer, 1-3 parts compatibilizer, 0.2-0.5 parts antioxidant, 0.5-1 part rubber activator, 1-2 parts PE-LD graft monomer, 0.1-0.3 parts PE-LD initiator, and 0.3-0.6 parts rubber desulfurizer.

[0029] Preferably, the base asphalt is 70# base asphalt.

[0030] Preferably, the ash content of the rock bitumen is not greater than 75%.

[0031] Preferably, the SBS is linear SBS with a molecular weight of 100,000 to 300,000.

[0032] Preferably, the rubber powder is waste tire rubber powder with a particle size of 40-80 mesh.

[0033] Preferably, the hydrogen peroxide has a mass fraction of 1%-5%.

[0034] Preferably, the hydrogen peroxide catalyst is CuFeO2, FeSO4, or catalase.

[0035] Preferably, the primary stabilizer is sulfur; the rock asphalt surface modifier is a silane coupling agent; the auxiliary stabilizer is calcium stearate; the compatibilizer is maleic anhydride-grafted polyethylene (PE-g-MAH); the antioxidant is a hindered phenolic antioxidant; the rubber activator is a composite system of zinc oxide and stearic acid, with a mass ratio of 1:1; the PE-LD graft monomer is maleic anhydride (MAH); the PE-LD initiator is dicumyl peroxide (DCP); and the rubber desulfurizer is benzoyl disulfide (DBD).

[0036] This invention also relates to a method for preparing the aforementioned rock asphalt composite modified asphalt, comprising the following steps:

[0037] (1) Raw material pretreatment:

[0038] a. Preparation of modified PE-LD: Low-density polyethylene (PE-LD) is added to a twin-screw extruder and heated to 160-180℃ to melt it. Then, PE-LD grafting monomer and PE-LD initiator are added, wherein the mass ratio of PE-LD, PE-LD grafting monomer and PE-LD initiator is 100:(4~6):(0.6~1.1). The melt grafting reaction is carried out at a screw speed of 200-250 r / min for 8-10 minutes to obtain grafted modified PE-LD. The grafted modified PE-LD is then pulverized to a particle size of 2-3 mm for later use.

[0039] b. Preparation of modified rubber powder: First, place the rubber powder in 1%-5% hydrogen peroxide, wherein the catalyst of the hydrogen peroxide is CuFeO2, FeSO4 or catalase, and react at 30-40℃ for 2-3 hours to obtain oxidized rubber powder; mix the oxidized rubber powder with rubber activator and rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 100:4:2, and place it in a mixer, and mix at 150-160℃ and 60-80 r / min for 20-30 minutes, while simultaneously purging with nitrogen gas for protection, to complete the desulfurization and activation modification; then dry the modified rubber powder at 100-120℃ for 2-3 hours for later use;

[0040] c. Rock asphalt treatment: Crush the rock asphalt to a particle size of no more than 5 mm, add the rock asphalt surface modifier, stir for 10-15 minutes at a stirring speed of 200-300 r / min to complete the surface modification;

[0041] (2) Preparation of composite modified asphalt: Heat the base asphalt to 155-175℃, add the surface-modified rock asphalt, stir for 35-45 minutes to dissolve it, keep the temperature at 165-185℃, and stir at 2000-4000 r / min; then add SBS, main stabilizer and auxiliary stabilizer, continue stirring for 50-60 minutes, keep the temperature at 185-195℃, and stir at 4000-5000 r / min; add compatibilizer and modified PE-LD, stir for 15-20 minutes, keep the temperature unchanged; finally add modified rubber powder and antioxidant, stir for 30-40 minutes, keep the temperature at 185-205℃, and stir at 3500-4500 r / min to obtain composite modified asphalt.

[0042] The chemical reaction principles involved in the raw material pretreatment process are as follows:

[0043] I. Chemical Reaction Principle for the Preparation of Modified PE-LD

[0044] Low-density polyethylene (PE-LD) is a non-polar polymer, exhibiting poor compatibility with highly polar base asphalt and rock asphalt. Introducing polar groups through a melt grafting reaction can improve its interfacial compatibility; the core reaction is as follows:

[0045] 1. Initiator decomposition and free radical formation: The PE-LD graft initiator dicumyl peroxide (DCP) undergoes thermal decomposition at 150-200℃ to generate cumyl phenyloxy free radical ((CH3)2C·-C6H5). This free radical has strong oxidizing properties and can abstract hydrogen atoms from the PE-LD molecular chain, causing the PE-LD molecular chain to form active free radical (PE·).

[0046] 2. Graft copolymerization: PE· undergoes an addition reaction with the carbon-carbon double bond of maleic anhydride (MAH, the graft monomer), causing the MAH molecule to covalently bind to the PE-LD chain, forming a PE-LD-g-MAH graft copolymer. The carboxyl group (-COOH) in the MAH molecule is a polar group, which can bind to polar components in the base asphalt (such as asphaltenes and resins) and the surface hydroxyl groups of minerals in rock asphalt through hydrogen bonding or polar interactions, significantly improving the compatibility of PE-LD with other components in the system.

[0047] II. Chemical Reaction Principles for the Preparation of Modified Adhesive Powder

[0048] Rubber powder (waste tire rubber) is mainly composed of natural rubber (polyisoprene) and styrene-butadiene rubber (styrene-butadiene copolymer). The presence of numerous cross-links (such as sulfur bridges) between its molecular chains makes it poorly soluble and dispersible in asphalt. The modification process synergistically improves its properties through oxidation and desulfurization activation. The reaction principle is as follows:

[0049] 1. Hydrogen peroxide oxidation modification: Under the catalysis of CuFeO2, FeSO4, or catalase, 1%-5% hydrogen peroxide (H2O2) undergoes a disproportionation reaction, generating hydroxyl radicals (·OH) and superoxide anions (·O2). - These reactive oxygen species can attack the unsaturated double bonds and side chains in the rubber molecular chain, causing oxidative breakage or introducing polar groups (such as carboxyl-COOH, hydroxyl-OH), which change the surface of the rubber powder from non-polar to polar, thereby enhancing its interfacial bonding with the asphalt matrix.

[0050] 2. Desulfurization activation reaction:

[0051] Desulfurization: The rubber desulfurizing agent benzoyl disulfide (DBD) decomposes at 140-180℃ to generate sulfur free radicals, which can break the sulfur bridge cross-links (-S) between rubber molecular chains. x -,x=1-8), reduce the cross-linking degree of the rubber powder, transforming it from rigid particles into an elastomer with a certain degree of fluidity, making it easier to disperse in asphalt.

[0052] Activation: The rubber activator (zinc oxide and stearic acid in a 1:1 ratio) reacts at high temperature to generate zinc stearate (zinc soap). Zinc soap can act as a vulcanization accelerator. On the one hand, it stabilizes the rubber molecular chain after desulfurization and prevents excessive degradation. On the other hand, it combines with the polar groups on the surface of rubber powder through coordination, further enhancing its compatibility with the polar components in asphalt.

[0053] Nitrogen protection: Prevents the rubber powder from being oxidized and degraded by oxygen in the air at high temperatures, thus maintaining the integrity of the rubber molecular chains.

[0054] III. Chemical Reaction Principles of Rock Asphalt Surface Modification

[0055] Rock bitumen contains a large amount of limestone minerals (such as CaCO3, MgCO3, etc.), and its surface has active sites such as hydroxyl groups (-OH), but its compatibility with non-polar matrix bitumen is poor. Treatment with silane coupling agents (such as KH550, KH560) can construct an "inorganic-organic" bridge. The reaction principle is as follows: Silane coupling agent molecules have a bifunctional structure: one end is a hydrolyzable siloxane alkyl group (such as -Si(OR)3), and the other end is an organic functional group (such as amino-NH2, epoxy-epoxy).

[0056] 1. Hydrolysis and Condensation of Siloxane Groups: During stirring, the silane coupling agent reacts with trace amounts of moisture on the surface of rock asphalt, resulting in the hydrolysis of siloxane groups to generate silanol groups (-Si(OH)3). Subsequently, these groups undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of minerals in the rock asphalt, forming Si-OM covalent bonds (where M is a metal ion in the mineral, such as Ca). 2+ Mg 2+ This allows the coupling agent to firmly bond to the surface of rock asphalt.

[0057] 2. Interfacial interaction of organic functional groups: The organic functional groups at the other end of the coupling agent can undergo physical adsorption or chemical interaction (such as hydrogen bonding between amino and carboxyl groups, and addition reaction between epoxy groups and rubber double bonds) with asphaltenes, gums (containing polar groups) or other organic modifiers (such as SBS, PE-LD-g-MAH) in the base asphalt, thereby eliminating the interfacial tension between rock asphalt and base asphalt, improving their compatibility, and reducing segregation.

[0058] The above chemical reactions improve the compatibility and dispersibility of each raw material with the matrix asphalt at the molecular level by introducing polar groups, breaking inert crosslinking bonds, and building interfacial bridges, laying the foundation for the subsequent preparation of high-performance composite modified asphalt.

[0059] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0060] Example 1:

[0061] S1: Take 6 parts of low-density polyethylene (PE-LD), add the PE-LD to a twin-screw extruder, heat to 170℃ to melt it, then add 2 parts of PE-LD graft monomer and 0.2 parts of PE-LD initiator, wherein the mass ratio of PE-LD, PE-LD graft monomer and PE-LD initiator is 100:4:0.7, and carry out the melt grafting reaction at a screw speed of 225 r / min for 9 minutes to obtain grafted modified PE-LD; crush the grafted modified PE-LD to a particle size of 3 mm for later use;

[0062] S2: Take 0.2 parts of hydrogen peroxide catalyst and add it to 8 parts of 3% peroxide solution. Add 8 parts of rubber powder to the above mixture. The catalyst for the hydrogen peroxide is CuFeO2. React at 40℃ for 2 hours to obtain oxidized rubber powder. Mix the oxidized rubber powder with 1 part of rubber activator and 0.4 parts of rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 100:4:2. Place it in a mixer and mix at 155℃ and 70 r / min for 25 minutes, while purging with nitrogen for protection to complete the desulfurization and activation modification. Then dry the modified rubber powder at 110℃ for 2-3 hours for later use to obtain modified rubber powder.

[0063] S3: Crush 10 parts of rock asphalt to a particle size of no more than 5 mm, add 0.5 parts of rock asphalt surface modifier, stir for 12 minutes at a stirring speed of 250 r / min to obtain surface-modified rock asphalt;

[0064] S4: Heat 70 parts of base asphalt to 165℃, add 10.5 parts of surface-modified rock asphalt, stir for 40 minutes to dissolve it, maintain the temperature at 175℃, and stir at a speed of 3000 r / min; then add 4 parts of SBS, 2 parts of main stabilizer and 0.5 parts of auxiliary stabilizer, continue stirring for 55 minutes, maintain the temperature at 190℃, and stir at a speed of 4500 r / min; add 2 parts of compatibilizer and modified PE-LD, stir for 17 minutes, and keep the temperature constant; finally add modified rubber powder and antioxidant, stir for 35 minutes, control the temperature at 195℃, and stir at a speed of 4000 r / min to obtain composite modified asphalt.

[0065] Example 2:

[0066] S1: Take 8 parts of low-density polyethylene (PE-LD), add the PE-LD to a twin-screw extruder, heat to 170℃ to melt it, then add 2 parts of PE-LD graft monomer and 0.2 parts of PE-LD initiator, wherein the mass ratio of PE-LD, PE-LD graft monomer and PE-LD initiator is 100:4:0.7, and carry out the melt grafting reaction at a screw speed of 225 r / min for 9 minutes to obtain grafted modified PE-LD; crush the grafted modified PE-LD to a particle size of 3 mm for later use;

[0067] S2: Take 0.2 parts of hydrogen peroxide catalyst and add it to 8 parts of 3% hydrogen peroxide. Add 10 parts of rubber powder to the above mixture. The catalyst for the above hydrogen peroxide is CuFeO2. React at 40℃ for 2 hours to obtain oxidized rubber powder. Mix the oxidized rubber powder with 1 part of rubber activator and 0.4 parts of rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 100:4:2. Put it into a mixer and mix at 155℃ and 70r / min for 25 minutes, while purging with nitrogen for protection to complete the desulfurization and activation modification. Then dry the modified rubber powder at 110℃ for 2-3 hours for later use to obtain modified rubber powder.

[0068] S3: Crush 15 parts of rock asphalt to a particle size of no more than 5 mm, add 0.75 parts of rock asphalt surface modifier, stir for 12 minutes at a stirring speed of 250 r / min to obtain surface-modified rock asphalt.

[0069] S4: Heat 60 parts of base asphalt to 165℃, add 15.75 parts of surface-modified rock asphalt, stir for 40 minutes to dissolve it, maintain the temperature at 175℃, and stir at a speed of 3000 r / min; then add 6 parts of SBS, 2 parts of main stabilizer and 0.5 parts of auxiliary stabilizer, continue stirring for 55 minutes, maintain the temperature at 190℃, and stir at a speed of 4500 r / min; add 2 parts of compatibilizer and modified PE-LD, stir for 17 minutes, and keep the temperature constant; finally add modified rubber powder and antioxidant, stir for 35 minutes, control the temperature at 195℃, and stir at a speed of 4000 r / min to obtain composite modified asphalt.

[0070] Example 3:

[0071] S1: Take 7 parts of low-density polyethylene (PE-LD), add the PE-LD to a twin-screw extruder, heat to 170℃ to melt it, then add 2 parts of PE-LD graft monomer and 0.2 parts of PE-LD initiator, wherein the mass ratio of PE-LD, PE-LD graft monomer and PE-LD initiator is 100:4:0.7, carry out melt grafting reaction at a screw speed of 225 r / min for 9 minutes to obtain grafted modified PE-LD; crush the grafted modified PE-LD to a particle size of 3 mm for later use;

[0072] S2: Take 0.2 parts of hydrogen peroxide catalyst and add it to 8 parts of 3% hydrogen peroxide. Add 12 parts of rubber powder to the above mixture. The catalyst for the above hydrogen peroxide is CuFeO2. React at 40℃ for 2 hours to obtain oxidized rubber powder. Mix the oxidized rubber powder with 1 part of rubber activator and 0.4 parts of rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 100:4:2. Put it into a mixer and mix at 155℃ and 70 r / min for 25 minutes, while purging with nitrogen for protection to complete the desulfurization and activation modification. Then dry the modified rubber powder at 110℃ for 2-3 hours for later use to obtain modified rubber powder.

[0073] S3: Crush 20 parts of rock asphalt to a particle size of no more than 5 mm, add 1 part of rock asphalt surface modifier, stir for 12 minutes at a stirring speed of 250 r / min to obtain surface-modified rock asphalt.

[0074] S4: Heat 50 parts of base asphalt to 165℃, add 21 parts of surface-modified rock asphalt, stir for 40 minutes to dissolve it, maintain the temperature at 175℃, and stir at a speed of 3000 r / min; then add 5 parts of SBS, 2 parts of main stabilizer and 0.5 parts of auxiliary stabilizer, continue stirring for 55 minutes, maintain the temperature at 190℃, and stir at a speed of 4500 r / min; add 2 parts of compatibilizer and modified PE-LD, stir for 17 minutes, and keep the temperature constant; finally add modified rubber powder and antioxidant, stir for 35 minutes, control the temperature at 195℃, and stir at a speed of 4000 r / min to obtain composite modified asphalt.

[0075] Comparative Example 1:

[0076] The raw material ratio of the modified low-density polyethylene was changed, while the remaining methods and steps were the same as in Example 1.

[0077] S1: Take 6 parts of low-density polyethylene (PE-LD), add the PE-LD to a twin-screw extruder, heat to 170℃ to melt it, then add 2 parts of PE-LD graft monomer and 0.2 parts of PE-LD initiator, wherein the mass ratio of PE-LD, PE-LD graft monomer and PE-LD initiator is 100:2:0.35, carry out melt grafting reaction at a screw speed of 225 r / min for 9 minutes to obtain grafted modified PE-LD; crush the grafted modified PE-LD to a particle size of 3 mm for later use;

[0078] S2: Take 0.2 parts of hydrogen peroxide catalyst and add it to 8 parts of 3% peroxide solution. Add 8 parts of rubber powder to the above mixture. The catalyst for the hydrogen peroxide is CuFeO2. React at 40℃ for 2 hours to obtain oxidized rubber powder. Mix the oxidized rubber powder with 1 part of rubber activator and 0.4 parts of rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 100:4:2. Place it in a mixer and mix at 155℃ and 70 r / min for 25 minutes, while purging with nitrogen for protection to complete the desulfurization and activation modification. Then dry the modified rubber powder at 110℃ for 2-3 hours for later use to obtain modified rubber powder.

[0079] S3: Crush 10 parts of rock asphalt to a particle size of no more than 5 mm, add 0.5 parts of rock asphalt surface modifier, stir for 12 minutes at a stirring speed of 250 r / min to obtain surface-modified rock asphalt;

[0080] S4: Heat 70 parts of base asphalt to 165℃, add 10.5 parts of surface-modified rock asphalt, stir for 40 minutes to dissolve it, maintain the temperature at 175℃, and stir at a speed of 3000 r / min; then add 4 parts of SBS, 2 parts of main stabilizer and 0.5 parts of auxiliary stabilizer, continue stirring for 55 minutes, maintain the temperature at 190℃, and stir at a speed of 4500 r / min; add 2 parts of compatibilizer and modified PE-LD, stir for 17 minutes, and keep the temperature constant; finally add modified rubber powder and antioxidant, stir for 35 minutes, control the temperature at 195℃, and stir at a speed of 4000 r / min to obtain composite modified asphalt.

[0081] Comparative Example 2:

[0082] The raw material ratio of the modified adhesive powder was changed, while the remaining methods and steps were the same as in Example 1.

[0083] S1: Take 6 parts of low-density polyethylene (PE-LD), add the PE-LD to a twin-screw extruder, heat to 170℃ to melt it, then add 2 parts of PE-LD graft monomer and 0.2 parts of PE-LD initiator, wherein the mass ratio of PE-LD, PE-LD graft monomer and PE-LD initiator is 100:4:0.7, and carry out the melt grafting reaction at a screw speed of 225 r / min for 9 minutes to obtain grafted modified PE-LD; crush the grafted modified PE-LD to a particle size of 3 mm for later use;

[0084] S2: Take 0.2 parts of hydrogen peroxide catalyst and add it to 8 parts of 3% peroxide solution. Add 8 parts of rubber powder to the above mixture. The catalyst for the hydrogen peroxide is CuFeO2. React at 40℃ for 2 hours to obtain oxidized rubber powder. Mix the oxidized rubber powder with 1 part of rubber activator and 0.4 parts of rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 100:2:1. Place it in a mixer and mix at 155℃ and 70 r / min for 25 minutes, while purging with nitrogen for protection to complete the desulfurization and activation modification. Then dry the modified rubber powder at 110℃ for 2-3 hours for later use to obtain modified rubber powder.

[0085] S3: Crush 10 parts of rock asphalt to a particle size of no more than 5 mm, add 0.5 parts of rock asphalt surface modifier, stir for 12 minutes at a stirring speed of 250 r / min to obtain surface-modified rock asphalt;

[0086] S4: Heat 70 parts of base asphalt to 165℃, add 10.5 parts of surface-modified rock asphalt, stir for 40 minutes to dissolve it, maintain the temperature at 175℃, and stir at a speed of 3000 r / min; then add 4 parts of SBS, 2 parts of main stabilizer and 0.5 parts of auxiliary stabilizer, continue stirring for 55 minutes, maintain the temperature at 190℃, and stir at a speed of 4500 r / min; add 2 parts of compatibilizer and modified PE-LD, stir for 17 minutes, and keep the temperature constant; finally add modified rubber powder and antioxidant, stir for 35 minutes, control the temperature at 195℃, and stir at a speed of 4000 r / min to obtain composite modified asphalt.

[0087] Comparative Example 3:

[0088] The raw material ratio of the modified adhesive powder was changed, while the remaining methods and steps were the same as in Example 1.

[0089] S1: Take 6 parts of low-density polyethylene (PE-LD), add the PE-LD to a twin-screw extruder, heat to 170℃ to melt it, then add 2 parts of PE-LD graft monomer and 0.2 parts of PE-LD initiator, wherein the mass ratio of PE-LD, PE-LD graft monomer and PE-LD initiator is 100:4:0.7, and carry out the melt grafting reaction at a screw speed of 225 r / min for 9 minutes to obtain grafted modified PE-LD; crush the grafted modified PE-LD to a particle size of 3 mm for later use;

[0090] S2: Take 0.2 parts of hydrogen peroxide catalyst and add it to 8 parts of 3% peroxide solution. Add 8 parts of rubber powder to the above mixture. The catalyst for the hydrogen peroxide is CuFeO2. React at 40℃ for 2 hours to obtain oxidized rubber powder. Mix the oxidized rubber powder with 1 part of rubber activator and 0.4 parts of rubber desulfurizer, wherein the mass ratio of oxidized rubber powder, rubber activator and rubber desulfurizer is 50:4:2. Place it in a mixer and mix at 155℃ and 70 r / min for 25 minutes, while purging with nitrogen for protection to complete the desulfurization and activation modification. Then dry the modified rubber powder at 110℃ for 2-3 hours for later use to obtain modified rubber powder.

[0091] S3: Crush 10 parts of rock asphalt to a particle size of no more than 5 mm, add 0.5 parts of rock asphalt surface modifier, stir for 12 minutes at a stirring speed of 250 r / min to obtain surface-modified rock asphalt;

[0092] S4: Heat 70 parts of base asphalt to 165℃, add 10.5 parts of surface-modified rock asphalt, stir for 40 minutes to dissolve it, maintain the temperature at 175℃, and stir at a speed of 3000 r / min; then add 4 parts of SBS, 2 parts of main stabilizer and 0.5 parts of auxiliary stabilizer, continue stirring for 55 minutes, maintain the temperature at 190℃, and stir at a speed of 4500 r / min; add 2 parts of compatibilizer and modified PE-LD, stir for 17 minutes, and keep the temperature constant; finally add modified rubber powder and antioxidant, stir for 35 minutes, control the temperature at 195℃, and stir at a speed of 4000 r / min to obtain composite modified asphalt.

[0093] Performance testing:

[0094] The rock asphalt modified asphalt prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following operations: (1) The modified asphalt sample was loaded into an aluminum tube and placed vertically in an oven at 163℃ for 48 hours. After cooling, it was cut into three sections: upper, middle and lower, and the softening point was measured respectively; (2) Aggregate, rock asphalt composite modified asphalt and mineral powder were mixed in a mass ratio of 100:(3-7):(3-5) to prepare asphalt mixture and tested; wherein, the mineral powder is limestone mineral powder; the aggregate is diabase, with 42% of the particles having a diameter of 10-20mm, 25% having a diameter of 5-10mm, 13% having a diameter of 3-5mm, and 20% having a diameter of 0-3mm; the specific performance parameters are shown in the table below:

[0095]

[0096] It is evident that Comparative Example 1, by altering the preparation method of modified low-density polyethylene, resulted in a decrease in overall performance due to changes in the raw material ratio. Comparative Examples 2 and 3, by altering the raw material ratio of the modified rubber powder, also showed performance inferior to the Examples. In other words, the comprehensive performance of Examples 1-3 was significantly better than that of the comparative examples, demonstrating that the raw material ratio (especially the ratio of rock asphalt, modified polyethylene, and modified rubber powder) and process parameters of the present invention play a crucial role. In summary, the reduced segregation softening point difference in the examples of the present invention reflects improved compatibility, the increased number of rutting cycles reflects enhanced high-temperature deformation resistance, and the improved Marshall stability reflects optimized mechanical bearing capacity.

[0097] Therefore, the rock asphalt prepared by this invention has good compatibility, good high-temperature deformation resistance, good mechanical properties, and good stability. It effectively solves the problems in the prior art where segregation occurs when a large amount of Buton rock asphalt is added to the base asphalt, weakening its performance-enhancing effect on the base asphalt, and the problem that adding rock asphalt alone cannot meet the requirements of high-performance asphalt.

[0098] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A rock asphalt complex modified asphalt, characterized by: The raw materials are composed of 50-70 parts of base pitch, 5-20 parts of rock pitch, 4-6 parts of SBS, 8-12 parts of rubber powder, 5-8 parts of low-density polyethylene (PE-LD), 1-3 parts of main stabilizer, 0.5-1.5 parts of rock pitch surface modifier, 8-12 parts of hydrogen peroxide, 0.1-0.3 parts of hydrogen peroxide catalyst, 0.3-0.8 parts of auxiliary stabilizer, 1-3 parts of compatibilizer, 0.2-0.5 parts of antioxidant, 0.5-1 part of rubber activator, 1-2 parts of PE-LD grafting monomer, 0.1-0.3 parts of PE-LD initiator, and 0.3-0.6 parts of rubber devulcanizing agent.

2. The rock asphalt complex modified asphalt of claim 1, characterized in that: The base pitch is 70# base pitch.

3. The rock asphalt composite modified asphalt of claim 1, wherein: The ash content of the rock pitch is not more than 75%.

4. The rock asphalt complex modified asphalt of claim 1, wherein: The SBS is linear SBS with a molecular weight of 100-300 thousand.

5. The rock asphalt complex modified asphalt of claim 1, wherein: The rubber powder is waste tire rubber powder with a particle size of 40-80 mesh.

6. The rock asphalt complex modified asphalt of claim 1, wherein: The mass fraction of the hydrogen peroxide is 1%-5%.

7. The rock asphalt complex modified asphalt of claim 1, wherein: The hydrogen peroxide catalyst is CuFeO2, FeSO4, or catalase.

8. The rock asphalt complex modified asphalt of claim 1, wherein: The main stabilizer is sulfur; the rock pitch surface modifier is silane coupling agent; the auxiliary stabilizer is calcium stearate; the compatibilizer is maleic anhydride grafted polyethylene (PE-g-MAH); the antioxidant is hindered phenolic antioxidant; the rubber activator is a composite system of zinc oxide and stearic acid with a mass ratio of 1:1; the PE-LD grafting monomer is maleic anhydride (MAH); the PE-LD initiator is dicumyl peroxide (DCP); and the rubber devulcanizing agent is dibenzoyl disulfide (DBD).

9. A method of producing rock pitch complex modified asphalt according to any one of claims 1 to 8, characterized by: The method comprises the following steps: (1) Raw material pretreatment: a. Modified PE-LD preparation: low-density polyethylene (PE-LD) is added to a twin-screw extruder, heated to 160-180°C to melt it, and then PE-LD grafting monomer and PE-LD initiator are added, with a mass ratio of PE-LD: PE-LD grafting monomer: PE-LD initiator being 100:(4-6):(0.6-1.1), and a screw rotation speed of 200-250 r / min for a melt grafting reaction for 8-10 minutes to obtain grafted modified PE-LD; the grafted modified PE-LD is crushed to a particle size of 2-3 mm for standby use; b. Modified rubber powder preparation: the rubber powder is first placed in 1%-5% hydrogen peroxide, with a catalyst of CuFeO2, FeSO4, or catalase, and reacted at 30-40°C for 2-3 hours to obtain oxidized rubber powder; the oxidized rubber powder is mixed with rubber activator and rubber devulcanizing agent, with a mass ratio of oxidized rubber powder: rubber activator: rubber devulcanizing agent being 100:4:2, and placed in an internal mixer at a temperature of 150-160°C and a rotation speed of 60-80 r / min for 20-30 minutes while nitrogen is introduced for protection to complete the devulcanization and activation modification; then the modified rubber powder is dried at 100-120°C for 2-3 hours for standby use; c. Rock pitch treatment: the rock pitch is crushed to a particle size of not more than 5 mm, and rock pitch surface modifier is added, stirred for 10-15 minutes at a stirring speed of 200-300 r / min to complete the surface modification. (2) Preparation of the composite modified asphalt: the base asphalt is heated to 155-175℃, the surface modified rock asphalt is added, stirred for 35-45 minutes to make it dissolved, the temperature is kept at 165-185℃, and the stirring speed is 2000-4000r / min; then the SBS, the main stabilizer and the auxiliary stabilizer are added, and the stirring is continued for 50-60 minutes, the temperature is kept at 185-195℃, and the stirring speed is 4000-5000r / min; the compatilizer and the modified PE-LD are added, and the stirring is continued for 15-20 minutes, the temperature is unchanged; finally the modified rubber powder and the antioxidant are added, the stirring is continued for 30-40 minutes, the temperature is controlled at 185-205℃, and the stirring speed is 3500-4500r / min, to obtain the composite modified asphalt.

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