Reactive high-modulus asphalt additive as well as preparation method and application thereof

Abstract

The invention relates to the technical field of asphalt pavement modifier materials, in particular to a reactive high-modulus asphalt additive as well as a preparation method and application thereof, and is technically characterized in that the reactive high-modulus asphalt additive comprises the following components in parts by weight: 20-40 parts of reactive polyolefin, 50-60 parts of polar SBS, 4-8 parts of a plasticizing aid and 10-20 parts of filler; the reactive polyolefin is prepared by self-crosslinking a grafted material A obtained by crosslinking vinyl trimethoxy silane and polyolefin and a catalytic material B containing polyolefin; wherein the catalytic material B comprises polyolefin, a catalyst and an antioxidant. Through the synergistic modification effect of the reactive polyolefin and polar SBS two-phase network on the matrix asphalt, the problems of insufficient instant solubility and poor compatibility of polyolefin and SBS in asphalt are solved, and the strength and toughness of the asphalt mixture are also improved.

Description

Technical Field

[0001] The invention relates to the technical field of asphalt pavement modifier materials, and in particular to a reactive high modulus asphalt additive, a preparation method and application thereof. Background Art

[0002] In recent years, asphalt pavement durability design and long-life pavement construction have become the main indicators for evaluating road construction and maintenance projects, and preventing pavement rutting caused by heavy loads and overloads is an important goal for achieving long-life asphalt pavements. High modulus asphalt concrete (HMAC) has a dynamic modulus of up to 14,000 MPa, showing excellent anti-rutting ability and durability, and has become one of the ways to achieve long-life asphalt pavement construction.

[0003] At present, my country's high modulus asphalt mixture is mainly achieved through low-grade asphalt, natural asphalt and adding high modulus asphalt additives to the mixture. Among them, the high modulus asphalt mixture prepared by low-grade asphalt and natural asphalt has poor high temperature performance and is difficult to meet the high temperature deformation resistance requirements of special sections such as road intersections. In order to further improve the application scope of high modulus asphalt mixtures, domestic and foreign researchers have put forward higher requirements for high modulus asphalt additives. At present, the components of high modulus asphalt additives are mainly polyolefins and thermoplastic elastomers SBS. However, polyolefins and thermoplastic elastomers still have certain problems in their use. For polyolefins, due to their high molecular weight, their solubility in asphalt is poor and they cannot be evenly dispersed in a short mixing process, which affects the modification effect of asphalt mixtures. In addition, polyolefins generally have a high degree of crystallinity, and irregular crystallization will occur during the cooling process of the mixture, which reduces the deformation capacity of the asphalt binder and leads to poor low-temperature performance and fatigue resistance of asphalt mixtures. In addition, the non-polar structural characteristics of polyolefins themselves make them less compatible with asphalt, and stress concentration is easily generated at the interface between the two phases after being stressed, which further weakens the low-temperature performance and fatigue resistance of asphalt mixtures. For SBS, the higher molecular weight also makes it less soluble in asphalt, and since the PS and PB segments in the SBS structure are both non-polar substances, this reduces the compatibility of SBS with asphalt, and the PB segment in SBS is composed of an unstable double bond structure, which is easy to age under thermal oxygen and ultraviolet conditions to break the double bonds and reduce the low-temperature performance and fatigue resistance of asphalt mixtures. Summary of the invention

[0004] The purpose of the present invention is to provide a reactive high modulus asphalt additive, which not only solves the problem of insufficient solubility and poor compatibility of polyolefins and SBS in asphalt through the synergistic modification of the matrix asphalt by the reactive polyolefin and polar SBS two-phase network, but also improves the strength and toughness of the asphalt mixture, so that the high modulus asphalt mixture meets the use requirements of high temperature deformation resistance, low temperature crack resistance, and medium temperature fatigue resistance.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] The present invention provides a reactive high modulus asphalt additive, which comprises the following components calculated by weight: 20 to 40 parts of reactive polyolefin, 50 to 60 parts of polar SBS, 4 to 8 parts of plasticizer and 10 to 20 parts of filler;

[0007] Reactive polyolefin, obtained by self-crosslinking a grafted material A obtained by crosslinking vinyltrimethoxysilane with polyolefin and a catalytic material B containing polyolefin;

[0008] The catalytic material B includes polyolefin, catalyst and antioxidant.

[0009] Furthermore, the molecular weight of the polyolefin is 10,000 to 20,000, and the molecular weight distribution index is 5.6 to 9.2.

[0010] Furthermore, for self-crosslinking, the water-producing agent used is a mixture of zinc acetate and zinc sulfate, with a mass ratio of 1:0.5 to 1.5.

[0011] Furthermore, the preparation method of the reactive polyolefin comprises the following steps:

[0012] The polyolefin, vinyl trimethoxysilane, initiator and antioxidant are mixed in proportion and then extruded and granulated to form grafted material A;

[0013] The polyolefin, catalyst and antioxidant are mixed in proportion and then extruded and granulated to form catalyst B material;

[0014] The grafted A material, the catalytic B material and the water-generating agent are uniformly mixed in proportion and self-crosslinked at room temperature to form a reactive polyolefin.

[0015] Furthermore, the polar SBS is prepared by a solution grafting method using SBS as a matrix, maleic anhydride as a main grafting monomer, and styrene as a co-grafting monomer. The molecular weight is 100,000 to 120,000, and the molecular weight distribution index is 1.01 to 1.05.

[0016] Furthermore, the preparation method of polar SBS comprises the following steps:

[0017] Add the solvent and SBS into a three-necked flask and stir until they are completely dissolved to obtain a solution;

[0018] The main monomer maleic anhydride, the co-monomer styrene and the initiator are added into the solution for mixed reaction to obtain polar SBS.

[0019] Furthermore, the plasticizer is a mixture of cyclohexane oil and polyethylene wax in a mass ratio of 1 to 1.5:1.

[0020] Furthermore, the filler is one or more of rock asphalt, lake asphalt, and coal liquefaction asphalt.

[0021] The second aspect of the present invention is to provide a method for preparing a reactive high modulus asphalt additive, comprising the following steps:

[0022] Premixing polar SBS and plasticizer according to proportion to obtain mixture 1;

[0023] The reactive polyolefin and the filler are uniformly mixed to obtain a mixture 2;

[0024] Mixture 1 and mixture 2 are uniformly mixed, melted, extruded and granulated to obtain a reactive high modulus asphalt additive.

[0025] The third aspect of the present invention is to provide an application of a reactive high modulus asphalt additive, comprising the following steps:

[0026] Add the reactive high modulus asphalt additive into the mixing tank and mix with the mineral material at 0.7% to 1.5% of the mineral material mass;

[0027] Add base asphalt binder at 4.0% to 4.8% of the mineral mass and mix evenly;

[0028] Add mineral powder according to the production mix ratio and mix evenly to form a high modulus asphalt mixture;

[0029] The evenly mixed high modulus asphalt mixture is placed in a material truck for transportation, paving and rolling.

[0030] Furthermore, an application of a reactive high modulus asphalt additive comprises the following steps:

[0031] Add reactive high modulus asphalt additive into the mixing cylinder of the asphalt mixing plant at a ratio of 0.7% to 1.5% of the mass ratio of the mineral material, and dry mix it with the hot mineral material preheated to 180-190°C for 15-20 seconds, so that the reactive high modulus asphalt additive is completely melted and spread on the surface of the hot mineral material;

[0032] Spray base asphalt preheated to 160-170℃ into the mixing cylinder of the asphalt mixing plant at 4.0%-4.8% of the mass ratio of the mineral material, and continue mixing for 30-40s;

[0033] Add mineral powder into the mixing cylinder of the asphalt mixing plant according to the production mix ratio, and continue stirring for 30 to 40 seconds until there is no white material and a high modulus asphalt mixture is formed;

[0034] The prepared high modulus asphalt mixture is placed in a material truck for transportation, paving and rolling.

[0035] In summary, the present invention has the following beneficial effects:

[0036] (1) The present invention utilizes a free radical-induced dehydrogenation reaction of polyolefins to achieve grafting, hydrolysis and crosslinking modification of silane on polyolefin molecular chains, thereby transforming the relatively linear molecular structure of polyolefins into a three-dimensional network structure, making chemical bonds the main form of intermolecular interaction. The hydroxyl active groups generated after silane hydrolysis can further enhance the compatibility of the reactive polyolefins with asphalt, making the reinforcing effect of the reactive polyolefins on asphalt more significant. In addition, the reactive polyolefins destroy their internal crystalline structure through step-by-step reactions, thereby reducing the crystallinity of the polyolefins, thereby solving the problems of high construction temperature and uneven dispersion of traditional polyolefin-modified asphalt.

[0037] (2) The present invention utilizes free radical polymerization to graft maleic anhydride onto the tertiary carbon and secondary carbon atoms of the PB segment of SBS. The introduction of the anhydride group can, on the one hand, produce chemical bonds with asphalt through diene addition reaction, thereby improving its compatibility with asphalt and also improving the property of SBS that double bonds are easily broken under thermal oxidation and ultraviolet aging conditions; on the other hand, through the chemical bonding between the anhydride group and the hydroxyl group, the compatibility between the polar SBS and the reactive polyolefin is improved, and the synergistic connection of the two-phase network is achieved. At the same time, the active group can produce functional group reactions with the filler and the matrix asphalt, which helps to improve the compatibility of the three, further improve its reinforcing effect on the matrix asphalt, and improve the low temperature performance and fatigue resistance of the high modulus asphalt mixture.

[0038] (3) The reactive high modulus asphalt additive provided by the present invention can change the reactivity of the high modulus asphalt additive by adjusting the grafting crosslinking degree of unsaturated silane and the grafting rate of maleic anhydride in polar SBS, and regulate the network density between the two-phase network of polar SBS and reactive polyolefin through the reaction activity, so as to achieve a balance between construction workability, low temperature performance and fatigue resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the synergistic connection between reactive polyolefin and polar SBS phases in asphalt.

[0040] Reference numerals

[0041] 1. Polar SBS network; 2. Reactive polyolefin network; 3. Reactive polyolefin self-crosslinking site; 4. Chemical bonding of the two-phase network; 5. Reactive polyolefin active site; 6. Polar SBS active site; 7. Asphalt component; 8. Asphalt-based filler; 9. Functional group reaction. DETAILED DESCRIPTION

[0042] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a reactive high modulus asphalt additive, a preparation method and an application thereof, as well as its specific implementation method, characteristics and effects are described in detail as follows.

[0043] Sources of raw materials used in the implementation methods and comparative examples:

[0044] Polyolefins: LD615, JL210, 2909 (melt index of 10-20 g / 10 min at 190°C and 2.16 kg load), Sinopec Group; LICOWAX PE 190, Shanghai Kaiyin Chemical Co., Ltd.

[0045] SBS: SBS JH7302 (molecular weight about 100000-120000), Ningbo Jinhai Chenguang Chemical Co., Ltd.

[0046] Grafting monomers: maleic anhydride, styrene, vinyltrimethoxysilane (A171), Shanghai Aladdin Biochemical Technology Co., Ltd.

[0047] Initiator: benzoyl peroxide, diisopropylbenzene peroxide, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0048] Catalyst: dibutyltin deoxysilicate, stannous octoate, Shanghai MacLean Biochemical Technology Co., Ltd.

[0049] Antioxidant: Tetrakis-[β-(3,5-di-tert-butyl)-4-hydroxyphenylether propionate] pentaerythritol (1010), Shanghai MacLean Biochemical Technology Co., Ltd.

[0050] Rubber oil: naphthenic oil, Shandong Taichang Petrochemical Technology Co., Ltd.

[0051] Asphalt-based fillers: rock asphalt, produced in Iran; lake asphalt, produced in Trinidad Island in Central America; coal liquefaction asphalt, State Energy Group.

[0052] Water-generating agent: zinc acetate, zinc sulfate, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0053] Solvent: xylene, anhydrous ethanol, Sinopharm Chemical Reagent Co., Ltd.

[0054] Asphalt: 70# base asphalt, Jiangsu Zhongyitong Road New Materials Co., Ltd.

[0055] This specific embodiment provides a reactive high modulus asphalt additive, which includes the following components calculated by weight: 20 to 40 parts of reactive polyolefin, 50 to 60 parts of polar SBS, 4 to 8 parts of plasticizer and 10 to 20 parts of filler;

[0056] Reactive polyolefin, obtained by self-crosslinking a grafted material A obtained by crosslinking vinyltrimethoxysilane with polyolefin and a catalytic material B containing polyolefin;

[0057] The catalytic material B includes polyolefin, catalyst and antioxidant.

[0058] In this specific embodiment, the reactive polyolefin is modified by melt extrusion silane self-crosslinking of polyolefin with vinyl trimethoxysilane, initiator and water-generating agent. After the crosslinking modification of polyolefin, its molecular structure changes from a relatively linear structure to a three-dimensional network structure, and the chemical bonds between molecules replace the van der Waals force, which reduces the crystallinity of polyolefin and improves the deformation resistance and low-temperature cracking resistance of polyolefin; thus, when modifying asphalt, it can well improve the high and low temperature performance of asphalt. In addition, the reactive polyolefin generates hydroxyl groups during the hydrolysis and condensation process, has a large reaction activity, can promote its compatibility with asphalt, and further improve the dispersion uniformity of polyolefin in asphalt.

[0059] In some preferred embodiments, the molecular weight of the polyolefin is 10,000 to 20,000, and the molecular weight distribution index is 5.6 to 9.2.

[0060] In some preferred embodiments, the polyolefin has a melt index of 10 to 20 g / 10 min at 190° C. and a load of 2.16 kg.

[0061] It can be understood that a molecular weight higher than 10,000 can ensure that polyolefins can enhance the modulus of asphalt, and a molecular weight less than 20,000 can ensure that the polyolefin-modified asphalt has a suitable viscosity within the mixing and compaction temperature range, and has better construction and workability, solving the problem of high construction temperature of high molecular weight polyolefin-modified asphalt; a wider molecular weight distribution can weaken the repulsion between polyolefins and asphaltene, and enhance the adsorption between polyolefins and saturated components, making it easier for polyolefins to be evenly dispersed in asphalt, and a higher melt index ensures the rapid solubility of polyolefins in asphalt, solving the problem of uneven dispersion of polyolefin-modified asphalt with a narrow molecular weight distribution.

[0062] In some preferred embodiments, the water-generating agent used for self-crosslinking is a mixture of zinc acetate and zinc sulfate, with a mass ratio of 1:0.5 to 1.5.

[0063] In some preferred embodiments, the method for preparing the reactive polyolefin comprises the following steps:

[0064] The polyolefin, vinyl trimethoxysilane, initiator and antioxidant are mixed in proportion and then extruded and granulated to form grafted material A;

[0065] The polyolefin, catalyst and antioxidant are mixed in proportion and then extruded and granulated to form catalyst B material;

[0066] The grafted A material, the catalytic B material and the water-generating agent are uniformly mixed in proportion and self-crosslinked at room temperature to form a reactive polyolefin.

[0067] More specifically, the method for preparing the reactive polyolefin comprises the following steps:

[0068] A1, 100 parts of polyolefin, 1-2 parts of vinyltrimethoxysilane, 0.1-0.3 parts of initiator, and 0.1 parts of antioxidant are mixed and melt-grafted at 170-200° C. through a twin-screw extruder to form grafted material A;

[0069] The initiator is diisopropylbenzene peroxide, which produces free radicals at a certain temperature to initiate the grafting reaction of silane and polyolefin; the antioxidant is tetrakis-[β-(3,5-di-tert-butyl)-4-hydroxyphenylether propionic acid] pentaerythritol (1010), which can effectively avoid the generation of cross-linking side reactions during the grafting process.

[0070] A2, 100 parts of polyolefin, 1 part of catalyst, and 0.8 parts of antioxidant are melt-granulated at 170-200° C. by a twin-screw extruder to form a catalyst B material;

[0071] The catalyst is a mixture of dibutyltin deceosilicate and stannous octoate, and the mass ratio between the two is 1:1; the antioxidant is the same as the antioxidant used in step A1.

[0072] A3. A catalyst B material and a water producing agent adding module are set at the middle end of the twin-screw extruder, and 90 parts of the grafted A material in A1, 10 parts of the catalyst B material prepared in step A2, and 1 to 3 parts of the water producing agent are melt-extruded at 170 to 200° C. through a twin-screw extruder. After granulation, the reaction-type polyolefin is obtained by placing it at room temperature for 3 to 5 days.

[0073] Among them, the water-generating agent is a mixture of zinc acetate and zinc sulfate, and the mass ratio between the two is 1:0.5-1.5; the complete dehydration temperature of the water-generating agent is about 110°C, and it can completely lose crystal water during the processing and molding process. The water-generating agent after dehydration can construct water molecule channels inside the polyolefin, accelerate the absorption and penetration of water molecules, and help accelerate the cross-linking of the system.

[0074] In some preferred embodiments, polar SBS is prepared by solution grafting method with SBS as the matrix, maleic anhydride as the main grafting monomer, styrene as the co-grafting monomer, and has a molecular weight of 100,000 to 120,000 and a molecular weight distribution index of 1.01 to 1.05.

[0075] It can be understood that the molecular weight of SBS is 100,000 to 120,000, and its molecular weight distribution index is 1.01 to 1.05. A molecular weight greater than 100,000 can ensure that SBS forms a three-dimensional network structure when modifying asphalt, which helps to improve the high and low temperature performance of asphalt; a molecular weight less than 120,000 can ensure that SBS is ground and dispersed more evenly during the shearing process, so that the viscosity of the modified asphalt is suitable and has better construction and workability; a narrow molecular weight distribution can improve the solubility of SBS in asphalt and enhance the compatibility of SBS in asphalt.

[0076] In some preferred implementations, the method for preparing polar SBS comprises the following steps:

[0077] Add the solvent and SBS into a three-necked flask and stir until they are completely dissolved to obtain a solution;

[0078] The main monomer maleic anhydride, the co-monomer styrene and the initiator are added into the solution for mixed reaction to obtain polar SBS.

[0079] More specifically, the preparation process of polar SBS is as follows:

[0080] B1. Add 10 g of SBS into a three-necked flask containing 100 mL of xylene and stir continuously until the SBS is completely dissolved.

[0081] B2. Add 1-2g maleic anhydride and 0.5-1g styrene to the three-necked flask in step B1. Heat the reaction mixture to 80°C, add the xylene solution containing the initiator through a dropping funnel under nitrogen protection, react for 5h, repeatedly rinse the cooled reactant with anhydrous ethanol, and then vacuum dry the precipitate at 40°C to obtain polar SBS.

[0082] The initiator is dibenzoyl peroxide; the amount of the initiator used is 3% relative to the total amount of SBS, maleic anhydride and styrene.

[0083] In some preferred embodiments, the plasticizer is a mixture of cyclohexane oil and polyethylene wax in a mass ratio of 1 to 1.5:1.

[0084] It can be understood that cyclohexane oil can pre-swell SBS, promote the processing efficiency of SBS, and improve the compatibility of SBS in asphalt; polyethylene wax can reduce the mixing temperature of asphalt mixture, has a significant warm mixing effect, and at the same time has a lubricating effect during the granulation process, thereby improving the processing efficiency of high modulus asphalt additives.

[0085] In some preferred embodiments, the filler is one or more of rock asphalt, lake asphalt, and coal liquefaction asphalt.

[0086] It can be understood that by adding fillers to the high modulus asphalt additive, the reactive polyolefin and polar SBS can be pre-dispersed in the asphalt-based filler, ensuring that the high modulus asphalt additive has good solubility, while also improving the uniformity and stability of the reactive polyolefin and polar SBS in the asphalt.

[0087] This specific embodiment also provides a method for preparing a reactive high modulus asphalt additive, comprising the following steps:

[0088] Premixing polar SBS and plasticizer according to proportion to obtain mixture 1;

[0089] The reactive polyolefin and the filler are uniformly mixed to obtain a mixture 2;

[0090] Mixture 1 and mixture 2 are uniformly mixed, melted, extruded and granulated to obtain a reactive high modulus asphalt additive.

[0091] More specifically, the preparation process of the high modulus asphalt additive is as follows:

[0092] S1. Mix 50-60 parts of polar SBS and 4-8 parts of plasticizer in proportion;

[0093] S2, 20-40 parts of reactive polyolefin and 10-20 parts of filler are mixed uniformly in a high-speed mixer;

[0094] S3, the materials in step S1 and step S2 are mixed evenly, and then melted, extruded and granulated to form a reactive high modulus asphalt additive, and the temperature of the melt extrusion section is 140-170°C.

[0095] Furthermore, the reactivity of the reactive high modulus asphalt additive is measured by a nuclear magnetic resonance instrument, wherein the reactive high modulus asphalt additive needs to be frozen and crushed into powder particles.

[0096] Furthermore, in order to reduce the mutual interference of active hydrogen on the active groups, the carboxyl and hydroxyl active groups of the reactive high modulus asphalt additive were respectively measured at room temperature using a nuclear magnetic resonance spectrometer. 1 H-NMR and 29For Si-NMR characterization, deuterated chloroform was used as solvent and tetramethylsilane as internal standard.

[0097] It can be understood that different active groups produce different chemical shifts and different absorption peak areas. Therefore, the purity of the analyte can be obtained by multiplying the integrated area of ​​a chemical shift of the analyte, the number of protons in the signal, the molar mass of the analyte and the ratio of the weighed mass of the analyte to the corresponding parameter of the standard by the purity of the standard. The sum of the purities of the carboxyl group and the hydroxyl group is used as the reaction activity of the reactive high modulus asphalt additive.

[0098] This specific embodiment also provides an application of a reactive high modulus asphalt additive, comprising the following steps:

[0099] Add the reactive high modulus asphalt additive into the mixing tank and mix with the mineral material at 0.7% to 1.5% of the mineral material mass;

[0100] Add base asphalt binder at 4.0% to 4.8% of the mineral mass and mix evenly;

[0101] Add mineral powder according to the production mix ratio and mix evenly to form a high modulus asphalt mixture;

[0102] The evenly mixed high modulus asphalt mixture is placed in a material truck for transportation, paving and rolling.

[0103] More specifically, the application of a reactive high modulus asphalt additive comprises the following steps:

[0104] P1. Add reactive high modulus asphalt additive into the mixing cylinder of the asphalt mixing plant at a ratio of 0.7% to 1.5% of the mass ratio of the mineral material, and dry mix it with the hot mineral material preheated to 180-190°C for 15-20s; so that the reactive high modulus asphalt additive is completely melted and spread on the surface of the hot mineral material.

[0105] P2. Spray base asphalt preheated to 160-170°C into the mixing cylinder of the asphalt mixing plant at a ratio of 4.0%-4.8% of the mass of the mineral material, and continue mixing for 30-40 seconds;

[0106] P3. Add mineral powder into the mixing cylinder of the asphalt mixing plant according to the production mix ratio, and continue stirring for 30 to 40 seconds until there is no white material and a high modulus asphalt mixture is formed;

[0107] P4. Place the prepared high modulus asphalt mixture in a material truck for transportation, paving and rolling.

[0108] The preparation method of high modulus asphalt in the embodiment and comparative example is:

[0109] Refer to Appendix A of "Asphalt Mixture Modification Additives Part 8: High Modulus Agents" (JT / T860.8-2023) to prepare high modulus asphalt. The shear temperature is 180°C, the shear speed is 4500r / min, and the shear time is 30min.

[0110] The preparation method of high modulus asphalt mixture (HFM-20) in the embodiment and comparative example is:

[0111] High modulus asphalt mixture (HFM-20) was prepared with reference to "Asphalt Mixture Modifier Additives Part 8: High Modulus Agents" (JT / T 860.8-2023). The typical mineral aggregate gradation composition is coarse aggregate (15.0-25.0 mm): coarse aggregate (10.0-15.0 mm): coarse aggregate (5.0-10.0 mm): coarse aggregate (3.0-5.0 mm): fine aggregate (0-3.0 mm): mineral powder = 11%: 28%: 17%: 15%: 26%: 3%.

[0112] Example 1

[0113] The reactive high modulus asphalt additive provided in this embodiment is calculated by weight and includes 20 parts of reactive polyolefin, 60 parts of polar SBS, 8 parts of plasticizer (mixed with cyclohexane oil and polyethylene wax in a mass ratio of 1.5:1), and 20 parts of rock asphalt.

[0114] Preparation of reactive polyolefins:

[0115] A1, 100 parts of polyolefin (LD 615), 1 part of vinyl trimethoxy silane, 0.1 part of initiator (dicumyl peroxide), and 0.1 part of antioxidant (1010) were mixed and melt-grafted through a twin-screw extruder at a mixing section temperature of 175° C. to form grafted material A;

[0116] A2, 100 parts of polyolefin (LD 615), 1 part of catalyst (dibutyltin december silicate and stannous octoate mixed in a ratio of 1:1), and 0.8 parts of antioxidant (1010) were melt-granulated by a twin-screw extruder at a mixing section temperature of 175° C. to form a catalyst B material;

[0117] A3. A catalyst B material and a water producing agent adding module are set at the middle end of the twin-screw extruder, and 90 parts of the grafted A material in A1, 10 parts of the catalyst B material in A2, and 3 parts of the water producing agent (zinc acetate and zinc sulfate are mixed at a ratio of 1:1.5) are melt-extruded through the twin-screw extruder. The temperature of the mixing section is 185°C. After granulation, the reaction polyolefin is left at room temperature for 3 days to obtain the reaction polyolefin. The gel content of the prepared reaction polyolefin is measured by reflux extraction method and is 80.1%.

[0118] Preparation of polar SBS:

[0119] B1. Add 10 g SBS (JH7302) into a three-necked flask containing 100 mL of xylene and stir continuously until the SBS is completely dissolved.

[0120] B2. Add 1 g of maleic anhydride and 0.5 g of styrene to the three-necked flask in B1, heat the reaction mixture to 80°C, add a xylene solution containing 3% of the initiator (dibenzoyl peroxide) relative to the total amount of SBS, maleic anhydride and styrene through a dropping funnel under nitrogen protection, react for 5 hours, repeatedly rinse the cooled reactants with anhydrous ethanol, and then dry the precipitate in vacuum at 40°C to obtain polar SBS. The grafting rate of the prepared polar SBS is 37.2% as measured by titration.

[0121] Preparation of high modulus asphalt additives:

[0122] S1. Mix 60 parts of polar SBS and 8 parts of plasticizer in proportion;

[0123] S2, 20 parts of reactive polyolefin and 20 parts of rock asphalt are mixed evenly in a high-speed mixer;

[0124] S3, the materials in step S1 and step S2 are mixed evenly, and then melted, extruded and granulated to form a reactive high modulus asphalt additive, and the temperature of the mixing section is 170°C.

[0125] The reactivity of the reactive high modulus asphalt additive was measured to be 48.3% by nuclear magnetic resonance technology.

[0126] The application of a reactive high modulus asphalt additive is as follows:

[0127] P1. Add reactive high modulus asphalt additive into the mixing cylinder of the asphalt mixing plant at a ratio of 1.1% of the mass of the mineral material, and dry mix it with the hot mineral material preheated to 185°C for 20 seconds; so that the reactive high modulus asphalt additive is completely melted and spread on the surface of the hot mineral material.

[0128] P2. Spray 70# base asphalt preheated to 165°C into the mixing cylinder of the asphalt mixing plant at a ratio of 4.4% of the mass of the mineral material, and continue mixing for 30 seconds;

[0129] P3. Add mineral powder into the mixing cylinder of the asphalt mixing plant according to the production mix ratio and continue mixing for 40 seconds until there is no white material and a high modulus asphalt mixture is formed;

[0130] P4. Place the high modulus asphalt mixture prepared in step P3 in a material truck for transportation, paving and rolling.

[0131] Embodiment 1 performance test:

[0132] Table 1. Test results of reactive high modulus asphalt additives in Example 1

[0133]

[0134] Example 2

[0135] The reactive high modulus asphalt additive provided in this embodiment includes, by weight, 40 parts of reactive polyolefin, 50 parts of polar SBS, 4 parts of plasticizer (mixture of cyclohexane oil and polyethylene wax at a ratio of 1.25:1), and 10 parts of lake asphalt.

[0136] Preparation of reactive polyolefins:

[0137] A1, 100 parts of polyolefin (JL 210), 1.5 parts of vinyltrimethoxysilane, 0.2 parts of initiator (dicumyl peroxide), and 0.1 parts of antioxidant (1010) were mixed and melt-grafted through a twin-screw extruder at a mixing section temperature of 175° C. to form grafted material A;

[0138] A2, 100 parts of polyolefin (JL 210), 1 part of catalyst (dibutyltin december silicate and stannous octoate mixed in a ratio of 1:1), and 0.8 parts of antioxidant (1010) were melt-granulated by a twin-screw extruder at a mixing section temperature of 175° C. to form a catalyst B material;

[0139] A3. A catalyst B material and a water-producing agent adding module are set at the middle end of a twin-screw extruder, and 90 parts of the grafted A material in step A1, 10 parts of the catalyst B material in A2, and 1 part of a water-producing agent (zinc acetate and zinc sulfate are mixed at a ratio of 1:0.5) are melt-extruded through a twin-screw extruder. The temperature of the mixing section is 185° C. After granulation, the pellet is placed at room temperature for 4 days to obtain a reactive polyolefin. The gel content of the prepared reactive polyolefin is measured by a reflux extraction method to be 68.3%.

[0140] Preparation of polar SBS:

[0141] B1. Add 10 g SBS (JH7302) into a three-necked flask containing 100 mL of xylene and stir continuously until the SBS is completely dissolved.

[0142] B2. Add 1.5 g of maleic anhydride and 0.75 g of styrene to the three-necked flask in step B1, heat the reaction mixture to 80° C., add a xylene solution containing 3% of the total amount of SBS, maleic anhydride and styrene through a dropping funnel under nitrogen protection, react for 5 h, repeatedly rinse the cooled reactant with anhydrous ethanol, and then dry the precipitate in vacuo at 40° C. to obtain polar SBS. The grafting rate of the prepared polar SBS is 39.7% as measured by titration.

[0143] Preparation of high modulus asphalt additives:

[0144] S1. Mix 50 parts of polar SBS and 4 parts of plasticizer in proportion;

[0145] S2, 40 parts of reactive polyolefin and 10 parts of lake asphalt are mixed evenly in a high-speed mixer;

[0146] S3. The materials in step S1 and step S2 are mixed evenly, and then melted, extruded and granulated to form a reactive high modulus asphalt additive. The temperature of the melt extrusion section is 170° C. The reaction activity of the reactive high modulus asphalt additive is measured by nuclear magnetic resonance technology to be 42.5%.

[0147] An application of a reactive high modulus asphalt additive is as follows:

[0148] P1. Add reactive high modulus asphalt additive into the mixing cylinder of the asphalt mixing plant at a ratio of 1.5% of the mass of the mineral material, and dry mix it with the hot mineral material preheated to 185°C for 20 seconds; so that the reactive high modulus asphalt additive is completely melted and spread on the surface of the hot mineral material.

[0149] P2. Spray 70# base asphalt preheated to 165°C into the mixing cylinder of the asphalt mixing plant at a ratio of 4.0% of the mass of the mineral material, and continue mixing for 30 seconds;

[0150] P3. Add mineral powder into the mixing cylinder of the asphalt mixing plant according to the production mix ratio and continue mixing for 40 seconds until there is no white material and a high modulus asphalt mixture is formed;

[0151] P4. Place the high modulus asphalt mixture prepared in step P3 in a material truck for transportation, paving and rolling.

[0152] Embodiment 2 performance test:

[0153] Table 2. Test results of reactive high modulus asphalt additives in Example 2

[0154]

[0155] Example 3

[0156] The reactive high modulus asphalt additive provided in this embodiment includes, calculated by weight, 30 parts of reactive polyolefin, 55 parts of polar SBS, 6 parts of plasticizer (cyclohexane oil and polyethylene wax mixed in a ratio of 1:1), and 15 parts of coal liquefaction asphalt.

[0157] Preparation of reactive polyolefins:

[0158] A1, 100 parts of polyolefin (2909), 2 parts of vinyltrimethoxysilane, 0.3 parts of initiator (dicumyl peroxide), and 0.1 parts of antioxidant (1010) were mixed and melt-grafted through a twin-screw extruder at a mixing section temperature of 175° C. to form grafted material A;

[0159] A2, 100 parts of polyolefin (2909), 1 part of catalyst (dibutyltin december silicate and stannous octoate mixed in a ratio of 1:1), and 0.8 parts of antioxidant (1010) were melt-granulated by a twin-screw extruder at a mixing section temperature of 175° C. to form a catalyst B material;

[0160] A3. A catalyst B material and a water-producing agent adding module are set at the middle end of a twin-screw extruder, and 90 parts of the grafted A material in step A1, 10 parts of the catalyst B material in A2, and 2 parts of a water-producing agent (zinc acetate and zinc sulfate mixed in a ratio of 1:1) are melt-extruded through a twin-screw extruder. The temperature of the mixing section is 185° C. After granulation, the pellet is placed at room temperature for 5 days to obtain a reactive polyolefin. The gel content of the prepared reactive polyolefin is measured by a reflux extraction method to be 75.7%.

[0161] Preparation of polar SBS:

[0162] B1. Add 10 g SBS (JH7302) into a three-necked flask containing 100 mL of xylene and stir continuously until the SBS is completely dissolved.

[0163] B2. Add 2 g of maleic anhydride and 1 g of styrene to the three-necked flask in step B1, heat the reaction mixture to 80° C., add a xylene solution containing 3% of the total amount of SBS, maleic anhydride and styrene through a dropping funnel under nitrogen protection, react for 5 h, repeatedly rinse the cooled reactants with anhydrous ethanol, and then dry the precipitate in vacuo at 40° C. to obtain polar SBS. The grafting rate of the prepared polar SBS is 34.5% as measured by titration.

[0164] Preparation of high modulus asphalt additives:

[0165] S1. Mix 55 parts of polar SBS and 6 parts of plasticizer in proportion;

[0166] S2, 30 parts of reactive polyolefin and 15 parts of coal liquefaction asphalt are mixed uniformly in a high-speed mixer;

[0167] S3. The materials in step S1 and step S2 are mixed evenly, and then melted, extruded and granulated to form a reactive high modulus asphalt additive. The temperature of the melt extrusion section is 170° C. The reaction activity of the reactive high modulus asphalt additive is measured by nuclear magnetic resonance technology to be 45.8%.

[0168] A method of using a reactive high modulus asphalt additive is as follows:

[0169] P1. Add reactive high modulus asphalt additive into the mixing cylinder of the asphalt mixing plant at a rate of 0.7% of the mass ratio of the mineral material, and dry mix it with the hot mineral material preheated to 185°C for 20 seconds, so that the reactive high modulus asphalt additive is completely melted and spread on the surface of the hot mineral material;

[0170] P2. Spray 70# base asphalt preheated to 165°C into the mixing cylinder of the asphalt mixing plant at a ratio of 4.8% of the mass of the mineral material, and continue mixing for 30 seconds;

[0171] P3. Add mineral powder into the mixing cylinder of the asphalt mixing plant according to the production mix ratio and continue mixing for 40 seconds until there is no white material and a high modulus asphalt mixture is formed;

[0172] P4. Place the high modulus asphalt mixture prepared in step P3 in a material truck for transportation, paving and rolling.

[0173] Embodiment 3 performance test:

[0174] Table 3. Test results of reactive high modulus asphalt additives in Example 3

[0175]

[0176] Comparative Example 1 (non-grafted cross-linked modified polyolefin)

[0177] The reactive high modulus asphalt additive provided in this comparative example includes, by weight, 20 parts of polyolefin (LD615), 60 parts of polar SBS, 8 parts of plasticizer (mixture of cyclohexane oil and polyethylene wax at a ratio of 1.5:1), and 20 parts of rock asphalt.

[0178] In this comparative example, a polyolefin that has not been silane-grafted, hydrolyzed and cross-linked is used to replace the reactive polyolefin (LD615). The rest of the preparation process of the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1.

[0179] The method of using the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1.

[0180] Performance test of comparative example 1:

[0181] Table 4. Test results of high modulus asphalt additives in Comparative Example 1

[0182]

[0183] Compared with Example 1, the melt index of the high modulus asphalt additive in Comparative Example 1 is significantly reduced, a small amount of particles are not completely melted when dry-mixed with aggregate at 180°C, and the reaction activity decays from 48.3 to 5.5; while the segregation of high modulus asphalt in Comparative Example 1 is increased to 17.2°C compared with 1.4 in Example 1; the minimum molding temperature corresponding to 3% void ratio of high modulus asphalt mixture is increased from 155°C to 170°C, the low temperature bending failure strain decays from 3054 to 1874, and the four-point bending fatigue life decays from >1 million times to 786,000 times. This shows that the polyolefin is modified by silane grafting hydrolysis and cross-linking to reduce the crystallinity and greatly improve the compatibility with polar SBS; under the synergistic enhancement of the two-phase network, the solubility and reaction activity of the high modulus asphalt additive are greatly improved, the compatibility with asphalt is improved, the construction and workability are increased, the storage stability of high modulus asphalt is improved, and the low temperature performance and fatigue resistance of high modulus asphalt mixture are improved.

[0184] Comparative Example 2 (Silane-grafted polyolefin without hydrolysis crosslinking)

[0185] The reactive high modulus asphalt additive provided in this comparative example is calculated by weight and includes 20 parts of silane-grafted polyolefin (LD615), 60 parts of polar SBS, 8 parts of plasticizer (cyclohexane oil and polyethylene wax mixed at a ratio of 1.5:1), and 20 parts of rock asphalt.

[0186] In this comparative example, silane-grafted polyolefin that has not been hydrolyzed and cross-linked is used to replace the reactive polyolefin (LD615). The rest of the preparation process of the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1.

[0187] The method of using the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1.

[0188] Performance test of comparative example 2:

[0189] Table 5. Test results of high modulus asphalt additives in Comparative Example 2

[0190]

[0191] Compared with Example 1, the melt index of the high modulus asphalt additive in Comparative Example 2 decayed from 28.5 to 11.5, and the reaction activity decayed from 48.3 to 14.8, indicating that the silane grafted polyolefin significantly reduced the crystallinity of the polyolefin after hydrolysis and crosslinking, and greatly increased the solubility and reaction activity of the high modulus asphalt additive; and the segregation of the high modulus asphalt in Comparative Example 1 was increased to 8.6°C compared with 1.4 in Example 1; the minimum molding temperature corresponding to 3% void ratio of the high modulus asphalt mixture was increased from 155°C to 165°C, the low temperature bending failure strain decayed from 3054 to 2113, and the four-point bending fatigue life decayed from >1 million times to 981,000 times. This shows that hydrolysis and crosslinking increase the compatibility between silane grafted polyolefin and polar SBS, enhance the synergistic enhancement between the two-phase network, and thus improve the compatibility between the high modulus asphalt additive and asphalt, improve the storage stability of high modulus asphalt, and improve the low temperature performance and fatigue resistance of high modulus asphalt mixture.

[0192] Comparative Example 3 (ungrafted modified SBS)

[0193] The reactive high modulus asphalt additive provided in this comparative example includes, by weight, 20 parts of reactive polyolefin, 60 parts of SBS, 8 parts of plasticizer (mixed with cyclohexane oil and polyethylene wax at a ratio of 1.5:1), and 20 parts of rock asphalt.

[0194] This comparative example uses SBS that has not been grafted and modified to replace the polar SBS. The rest of the preparation process of the reactive high modulus asphalt additive provided in this comparative example is the same as that of Example 1.

[0195] The method of using the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1.

[0196] Performance test of comparative example 3:

[0197] Table 6. Test results of high modulus asphalt additives in Comparative Example 3

[0198]

[0199] Compared with Example 1, the melt index of the high modulus asphalt additive in Comparative Example 3 decayed from 28.5 to 15.2, and the reactivity decayed from 48.3 to 6.9; the segregation of high modulus asphalt in Comparative Example 3 was increased to 16.4°C compared with 1.4 in Example 1; the low-temperature bending failure strain of the high modulus asphalt mixture decayed from 3054 to 1983, and the four-point bending fatigue life decayed from >1 million times to 814,000 times. This shows that polar SBS and reactive polyolefins have better two-phase synergistic reinforcement, further reduce the crystallinity of reactive polyolefins, improve the compatibility of high modulus asphalt additives and asphalt, improve the storage stability of high modulus asphalt, and thus improve the low-temperature performance and fatigue resistance of high modulus asphalt mixtures.

[0200] Comparative Example 4 (low reactivity)

[0201] The reactive high modulus asphalt additive provided in this comparative example is calculated by weight and includes 20 parts of reactive polyolefin (LD615), 60 parts of polar SBS, 8 parts of plasticizer (mixed with cyclohexane oil and polyethylene wax at a ratio of 1.5:1), and 20 parts of rock asphalt.

[0202] In this comparative example, the gel content of the reactive polyolefin is regulated by reducing the content of the catalyst B material and the water producing agent, and the grafting rate of the polar SBS is regulated by reducing the content of the main monomer and the co-monomer to prepare a high modulus asphalt additive with low reactivity. The remaining preparation process of the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1. The gel content of the reactive polyolefin prepared is measured to be 35.3% by the reflux extraction method, the grafting rate of the polar SBS prepared is measured to be 17.9% by the titration method, and the reaction activity of the reactive high modulus asphalt additive is measured to be 24.6% by the nuclear magnetic resonance technology.

[0203] The method of using the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1.

[0204] Performance test of comparative example 4:

[0205] Table 7. Test results of high modulus asphalt additives in Comparative Example 4

[0206]

[0207] Compared with Example 1, the reactivity of the high modulus asphalt additive in Comparative Example 4 decayed from 48.3 to 24.6; while the dynamic stability of the high modulus asphalt mixture decayed from 12653 to 9283, the low temperature bending failure strain decayed from 3054 to 2301, the dynamic modulus decayed from 15081 to 12374, and the four-point bending fatigue life decayed from >1 million times to 971,000 times. This shows that when the reactivity of the high modulus asphalt additive is low, the fewer active sites between the polar SBS and the reactive polyolefin lead to weaker chemical bonding, resulting in a lower network density between the two-phase network and insufficient stability, which makes the improvement of the high temperature deformation resistance, low temperature crack resistance and medium temperature fatigue resistance of the high modulus asphalt mixture relatively limited.

[0208] Comparative Example 5 (High Reactivity)

[0209] The reactive high modulus asphalt additive provided in this comparative example includes, by weight, 20 parts of reactive polyolefin, 60 parts of polar SBS, 8 parts of plasticizer (mixed with cyclohexane oil and polyethylene wax at a ratio of 1.5:1), and 20 parts of rock asphalt.

[0210] In this comparative example, a high-reactivity high-modulus asphalt additive is prepared by increasing the content of catalyst B material and water-producing agent to control the gel content of the reactive polyolefin and by increasing the content of the main monomer and the co-monomer to control the grafting rate of the polar SBS. The remaining preparation process of the reactive high-modulus asphalt additive provided in this comparative example is the same as that in Example 1. The gel content of the prepared reactive polyolefin is measured to be 90.3% by reflux extraction method, the grafting rate of the prepared polar SBS is measured to be 48.6% by titration method, and the reaction activity of the reactive high-modulus asphalt additive is measured to be 69.1% by nuclear magnetic resonance technology.

[0211] The method of using the reactive high modulus asphalt additive provided in this comparative example is the same as that in Example 1.

[0212] Performance test of comparative example 5:

[0213] Table 8. Test results of high modulus asphalt additives in Comparative Example 5

[0214]

[0215] Compared with Example 1, the reactivity of the high modulus asphalt additive in Comparative Example 5 is increased from 48.3 to 69.1; the apparent viscosity of the high modulus asphalt in Comparative Example 5 is increased from 2.1Pa·s to 3.5Pa·s; the low-temperature bending failure strain of the high modulus asphalt mixture decays from 3054 to 2544, and the four-point bending fatigue life decays from >1 million times to 989,000 times. This shows that when the reactivity of the high modulus asphalt additive is high, the more active sites between the polar SBS and the reactive polyolefin lead to a stronger chemical bonding effect, which makes the network density between the two-phase network too large, increases the viscosity of the high modulus asphalt, and reduces the construction and workability; and the increase in network density weakens the spreading and infiltration effect of the high modulus asphalt additive and the asphalt component on the aggregate surface, making it unevenly distributed on the aggregate surface, thereby reducing the low temperature performance and fatigue resistance of the high modulus asphalt mixture.

[0216] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been presented as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A reactive high modulus asphalt additive, characterized in that: Calculated by weight, it includes the following components: 20-40 parts of reactive polyolefin, 50-60 parts of polar SBS, 4-8 parts of plasticizer and 10-20 parts of filler; The reactive polyolefin is prepared by self-crosslinking a grafted material A obtained by crosslinking vinyltrimethoxysilane with polyolefin and a catalytic material B containing polyolefin; Wherein, the catalytic material B comprises polyolefin, catalyst and antioxidant.

2. A reactive high modulus asphalt additive according to claim 1, characterized in that: The molecular weight of the polyolefin is 10000-20000, and the molecular weight distribution index is 5.6-9.

2.

3. A reactive high modulus asphalt additive according to claim 1, characterized in that: The water-producing agent used in the self-crosslinking is a mixture of zinc acetate and zinc sulfate, with a mass ratio of 1:0.5-1.

5.

4. A reactive high modulus asphalt additive according to claim 3, characterized in that: The method for preparing the reactive polyolefin comprises the following steps: The polyolefin, vinyl trimethoxysilane, initiator and antioxidant are mixed in proportion and then extruded and granulated to form grafted material A; The polyolefin, catalyst and antioxidant are mixed in proportion and then extruded and granulated to form catalyst B material; The grafted A material, the catalytic B material and the water-generating agent are uniformly mixed in proportion and self-crosslinked at room temperature to form a reactive polyolefin.

5. A reactive high modulus asphalt additive according to claim 1, characterized in that: The polar SBS is prepared by solution grafting method with SBS as the matrix, maleic anhydride as the main grafting monomer and styrene as the co-grafting monomer, and has a molecular weight of 100000-120000 and a molecular weight distribution index of 1.01-1.

05.

6. A reactive high modulus asphalt additive according to claim 5, characterized in that: The preparation method of the polar SBS comprises the following steps: Add the solvent and SBS into a three-necked flask and stir until they are completely dissolved to obtain a solution; The main monomer maleic anhydride, the co-monomer styrene and the initiator are added into the solution for mixed reaction to obtain polar SBS.

7. A reactive high modulus asphalt additive according to claim 1, characterized in that: The plasticizer is a mixture of naphthenic oil and polyethylene wax, with a mass ratio of 1 to 1.5:

1.

8. A reactive high modulus asphalt additive according to claim 1, characterized in that: The filler is one or more of rock asphalt, lake asphalt, and coal liquefaction asphalt.

9. The method for preparing a reactive high modulus asphalt additive according to any one of claims 1 to 8, characterized in that: The steps include: Premixing polar SBS and plasticizer according to proportion to obtain mixture 1; The reactive polyolefin and the filler are uniformly mixed to obtain a mixture 2; Mixture 1 and mixture 2 are uniformly mixed, melted, extruded and granulated to obtain a reactive high modulus asphalt additive.

10. The use of a reactive high modulus asphalt additive according to any one of claims 1 to 8, characterized in that: The steps include: Add the reactive high modulus asphalt additive into the mixing tank and mix with the mineral material at 0.7% to 1.5% of the mineral material mass; Add base asphalt binder at 4.0% to 4.8% of the mineral mass and mix evenly; Add mineral powder according to the production mix ratio and mix evenly to form a high modulus asphalt mixture; The evenly mixed high modulus asphalt mixture is placed in a material truck for transportation, paving and rolling.

Images