Preparation method of warm-mixed odorless asphalt

Abstract

The invention belongs to the technical field of road engineering materials, and particularly relates to a preparation method of warm-mixed odorless asphalt, which comprises the following steps: heating matrix asphalt to 140-150 DEG C, adding a composite warm-mixing agent (fatty acid amide, a polyoxyethylene ether interfacial agent, zinc octoate and epoxidized soybean oil) and an odorless agent (diatomite) according to a specific ratio, and uniformly mixing to obtain the warm-mixed odorless asphalt. And carrying out multi-stage stirring, cooling, adding the modifier and the mineral filler, and finally cooling and discharging. In the preparation process, the addition amount of each component, the stirring speed and the temperature change are controlled, so that the warm mixing agent effectively reduces the construction temperature, the odor removing agent adsorbs odor components, and the modifier improves the asphalt performance. The method can be used for preparing an asphalt mixture in road construction, and is beneficial to improving construction conditions and asphalt pavement performance.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering materials. More specifically, the present invention relates to a preparation method of warm mix and odorless asphalt. Background Art

[0002] In the field of road engineering, during the preparation and construction process of asphalt materials, the problems of too high construction temperature and odor volatilization are technical problems to be solved urgently. Traditional asphalt mixtures need to heat the matrix asphalt to 160 - 180 °C to meet the construction fluidity requirements, which not only increases energy consumption, but also pollutes the environment with gases such as hydrocarbons and sulfides volatilized from asphalt at high temperatures, and endangers the health of construction workers. Although existing warm mix asphalt technologies reduce the construction temperature by adding warm mix additives, the synergistic effect of common warm mix additive components (such as single surfactants or waxes) and matrix asphalt is limited, and it is difficult to stably control the discharge temperature below 90 °C, and there is still room for improvement in the warm mix effect.

[0003] In terms of odor treatment, the odor components volatilized from asphalt are complex. The existing odor treatment methods are relatively simple. Some processes do not specifically set an odorless link, or the odorless materials used have insufficient compatibility with asphalt, resulting in insignificant odor adsorption effect. At the same time, the addition process of warm mix additives and odorless agents lacks clear parameter control, such as stirring rate, addition sequence, and temperature range, etc., which may cause insufficient dispersion of components and affect the comprehensive effect of warm mix and odorless.

[0004] Therefore, how to effectively reduce the construction temperature while ensuring the construction performance of asphalt through reasonable component design and process optimization, and reduce odor emissions through targeted odorless materials and process steps has become a technical problem urgently to be solved in this field. Summary of the Invention

[0005] The object of the present invention is to provide a preparation method of warm mix and odorless asphalt, which reduces the asphalt viscosity through a composite warm mix additive, reduces the discharge temperature to 72 - 85 °C, significantly reduces energy consumption; the odorless agent adsorbs asphalt volatiles and improves the construction environment; multi-stage stirring ensures uniform dispersion of components, and combined with multi-stage temperature control, improves the stability and road performance of asphalt.

[0006] To achieve these objects and other advantages of the present invention, a preparation method of warm mix and odorless asphalt is provided, including the following steps:

[0007] After heating the base asphalt to 140 - 150 °C, a compound warm mix additive and an odorless agent are added to the base asphalt. Then, a screw stirrer is used to stir at a speed of 180 - 220 revolutions per minute for 20 - 30 minutes to form a first mixture; wherein, the compound warm mix additive includes fatty acid amide, polyoxyethylene ether surfactant, zinc octoate, and epoxidized soybean oil, and the mass ratio of the four is 2.8 - 3.2:0.9 - 1.1:0.4 - 0.6:0.2 - 0.4; the addition amount of the compound warm mix additive is 0.7 - 1.3% of the mass of the base asphalt; the odorless agent includes diatomite, and the addition amount of the odorless agent is 0.5 - 0.9% of the mass of the base asphalt;

[0008] After cooling the first mixture to 118 - 132 °C, a modifier is added, and then the screw stirrer is maintained at a speed of 180 - 220 revolutions per minute and continues to stir for 30 - 40 minutes to form a second mixture; wherein, the modifier contains styrene - butadiene block copolymer, and the total mass of the modifier is 3.5 - 6.5% of the mass of the base asphalt;

[0009] Mineral filler is added to the second mixture, and then the temperature is maintained at 118 - 132 °C and stirred for 12 - 18 minutes to form a third mixture; wherein, the mineral filler is composed of limestone powder and modified bentonite, and the mass ratio of the two is 6.5 - 7.5:0.8 - 1.2, and the addition amount of the mineral filler is 4.5 - 7.5% of the total mass of the base asphalt, compound warm mix additive, odorless agent, and modifier;

[0010] After cooling the third mixture to 72 - 85 °C, it is discharged.

[0011] Preferably, in the preparation method of the warm mix odorless asphalt, the compound warm mix additive satisfies the following physical and chemical parameters: the carbon chain length of the fatty acid amide is C16 - C18, and the saponification value is 170 - 210 mgKOH / g; the polyoxyethylene ether surfactant is fatty alcohol polyoxyethylene ether, the HLB value is 11.5 - 14.5, and the ethylene oxide addition number is 7 - 11; the zinc content of zinc octoate is 10 - 16%, calculated as the mass percentage of zinc element in zinc octoate; the hydroxyl value of epoxidized soybean oil is 38 - 52 mgKOH / g;

[0012] The silicon dioxide content of diatomite ≥ 85%, calculated as the mass percentage of silicon dioxide in diatomite, and the specific surface area is 30 - 50 m 2 / g;

[0013] The mass ratio of the compound warm mix additive to the odorless agent is 1.4:1 - 2.6:1;

[0014] The styrene content of the styrene - butadiene block copolymer is 28 - 37%;

[0015] The calcium carbonate content of the limestone powder is ≥90%, and the particle size is ≤0.075 mm.

[0016] Preferably, in the preparation method of the warm mix odorless asphalt, the modifier further includes maleic anhydride grafted polyethylene and nano-montmorillonite, and the mass ratio of the three is styrene-butadiene block copolymer: maleic anhydride grafted polyethylene: nano-montmorillonite = 1:0.5:0.3, and the total addition amount of the modifier is 3.5-6.5% of the mass of the base asphalt.

[0017] Preferably, in the preparation method of the warm mix odorless asphalt, the heating process of the base asphalt is carried out in two stages:

[0018] In the first stage, the base asphalt is heated from room temperature to 125-135°C at a heating rate of 4-6°C per minute and kept at this temperature for 10-15 minutes;

[0019] In the second stage, it is continuously heated to 140-150°C at a heating rate of 2-3°C per minute, and after reaching the target temperature, the composite warm mix agent and the odorless agent are added.

[0020] Preferably, in the preparation method of the warm mix odorless asphalt, before the limestone powder is used, it is pretreated through the following steps:

[0021] A double-layer gradient filter screen is adopted. The upper layer is a corrugated stainless steel filter screen with a pore size of 2.5-3.0 mm, and the lower layer is a plain woven galvanized filter screen with a pore size of 2.0-2.5 mm; the filtration pressure is controlled at 0.15-0.25 MPa, and the surface of the filter screen is pre-coated with a nano-silica anti-sticking layer with a mass fraction of 0.5-1.0%; the discharging temperature after filtration is controlled at 108-117°C;

[0022] The cooling method is specifically as follows:

[0023] The filtered asphalt is cooled in two stages. In the first stage, it is cooled from 108-117°C to 95-100°C at a rate of 3.0-3.5°C per minute for 5-8 minutes; in the second stage, it is cooled from 95-100°C to 72-85°C at a rate of 2.0-2.5°C per minute for 12-15 minutes.

[0024] Preferably, in the preparation method of the warm mix odorless asphalt, before the limestone powder is used, it is pretreated through the following steps:

[0025] Impregnate limestone powder in a stearic acid ethanol solution with a mass fraction of 3 - 5% at a solid - liquid mass ratio of 1:3 - 1:5, and perform ultrasonic treatment at 80 - 90 °C for 20 - 30 minutes. The ultrasonic power density is 0.5 - 0.8 W / mL, and the frequency is 40 - 60 kHz; after treatment, perform centrifugal separation at a centrifugal speed of 3000 - 4000 rpm for 10 - 15 minutes, and vacuum - dry the solid product at 60 - 70 °C for 2 - 3 hours;

[0026] The modified bentonite is prepared through the following steps:

[0027] Mix bentonite with deionized water at a mass ratio of 1:10 - 1:15, add cetyltrimethylammonium bromide, and its addition amount is 15 - 20% of the dry - basis mass of bentonite. Stir and react at 50 - 60 °C for 4 - 6 hours to enable cetyltrimethylammonium bromide to enter the interlayer of bentonite through ion exchange to form an organic modified layer. After the reaction, perform suction filtration and wash with water until there are no free bromide ions in the filtrate, and dry the solid to constant weight at 80 - 90 °C to obtain organic bentonite;

[0028] Mix the above - prepared organic bentonite with a γ - aminopropyltriethoxysilane ethanol solution with a mass fraction of 2 - 4% at a solid - liquid mass ratio of 1:5 - 1:8, perform ultrasonic treatment at 60 - 70 °C for 30 - 40 minutes, perform centrifugal separation after treatment, and vacuum - dry the solid at 60 - 70 °C for 2 - 3 hours to obtain modified bentonite.

[0029] Preferably, in the preparation method of the warm - mix odorless asphalt, the composite warm - mix agent further includes nano - graphene oxide, and the addition amount of nano - graphene oxide is 0.1 - 0.3% of the total mass of the composite warm - mix agent; the total addition amount of the composite warm - mix agent is 0.7 - 1.3% of the mass of the matrix asphalt;

[0030] The preparation method of the nano - graphene oxide is as follows:

[0031] Add natural graphite powder to a mixed acid of concentrated sulfuric acid and concentrated phosphoric acid, where the volume ratio of concentrated sulfuric acid to concentrated phosphoric acid is 9:1. Stir for 30 minutes under ice - bath conditions, then slowly add potassium permanganate, and the mass ratio of potassium permanganate to graphite powder is 6:1. Control the reaction temperature not to exceed 20 °C, and stir and react for 2 hours; raise the temperature of the reaction system to 50 °C, continue to stir and react for 12 hours, then slowly pour the reaction solution into ice water, and at the same time add a 30% mass - fraction hydrogen peroxide solution until the color of the solution becomes bright yellow, stir evenly and then let it stand for precipitation;

[0032] Wash the precipitate with deionized water repeatedly until it is neutral, then perform centrifugal separation, and vacuum - dry the obtained solid at 60 °C for 24 hours to obtain graphene oxide;

[0033] Disperse graphene oxide in absolute ethanol to form a graphene oxide dispersion with a mass fraction of 0.5 - 1%, add γ-aminopropyltriethoxysilane, an amino-silane coupling agent, to it, with an addition amount of 1 - 2% of the mass of graphene oxide, and reflux and stir at 80 °C for 6 hours to cause a condensation reaction between the amino-silane coupling agent and the hydroxyl groups on the surface of graphene oxide to form a grafted modification layer; after the reaction, centrifuge the product, wash it with absolute ethanol multiple times, and then vacuum dry it at 60 °C for 12 hours to obtain nano-graphene oxide grafted with an amino-silane coupling agent on the surface;

[0034] The dispersion treatment steps of the nano-graphene oxide are as follows:

[0035] Take 1 / 3 - 1 / 2 of the total mass of epoxy soybean oil in the composite warm mix additive and add nano-graphene oxide to a reaction vessel, perform ultrasonic treatment at 50 - 60 °C, with an ultrasonic frequency of 40 - 60 kHz and a power density of 0.3 - 0.5 W / mL, and a treatment time of 10 - 15 minutes to uniformly disperse the nano-graphene oxide in this part of the epoxy soybean oil;

[0036] Subsequently, continue ultrasonic treatment for 5 - 8 minutes to cause a condensation reaction between the amino-silane coupling agent and the hydroxyl groups on the surface of nano-graphene oxide to form a grafted modification layer, and obtain a pre-dispersed nano-graphene oxide mixture;

[0037] Mix the remaining epoxy soybean oil with fatty acid amide, polyoxyethylene ether surfactant, and zinc octoate, and synchronously add them to the matrix asphalt together with the above-mentioned pre-dispersed nano-graphene oxide mixture, control the rotation speed of the helical stirrer to be 200 - 220 revolutions per minute, the shear rate ≥ 600 s-1, and continuously stir for 8 - 10 minutes to uniformly disperse the nano-graphene oxide in the asphalt system through the action of mechanical shear force.

[0038] Preferably, in the preparation method of the warm mix odorless asphalt, the odorless agent further includes activated carbon, zeolite molecular sieve, and amphiphilic surfactant, and the mass ratio of diatomite, activated carbon, zeolite molecular sieve, and amphiphilic surfactant is 5:3:1:0.5; the total addition amount of the odorless agent is 0.5 - 0.9% of the mass of the matrix asphalt;

[0039] The diatomite was pretreated before use, and its pretreatment method is as follows:

[0040] Immerse the diatomite in a hydrochloric acid solution with a mass fraction of 5 - 8%, with a solid-liquid ratio of 1:4 - 1:6, stir at 60 - 70 °C for 1 - 2 hours to remove impurities, and then wash with water until neutral and dry;

[0041] The activated carbon was pretreated before use, and its pretreatment method is as follows:

[0042] The activated carbon is activated at 600 - 700 °C for 1 - 1.5 hours under nitrogen protection. After cooling, it is impregnated with a ferric nitrate solution with a mass fraction of 1 - 2%, and the solid-liquid ratio is 1:3 - 1:5. After drying, iron oxide is loaded, and the content of Fe3O4 is 3 - 5% of the mass of the activated carbon;

[0043] The zeolite molecular sieve was pretreated before use, and the pretreatment method is as follows:

[0044] The zeolite molecular sieve is mixed with an aqueous solution of cetyltrimethylammonium bromide with a mass fraction of 2 - 4% according to a solid-liquid ratio of 1:5 - 1:8, and ion exchange is carried out at 80 - 90 °C for 3 - 4 hours to adjust the pore size to 0.5 - 0.8 nm;

[0045] The amphiphilic surfactant is a polyethylene glycol - polypropylene glycol block copolymer with a molecular weight of 2000 - 3000 and an HLB value of 14 - 16.

[0046] Preferably, in the preparation method of the warm mix and odorless asphalt, the maleic anhydride grafted polyethylene is prepared by the following melt grafting method:

[0047] Low-density polyethylene particles, maleic anhydride, diisopropylbenzene peroxide and nano-zinc oxide are mixed according to a mass ratio of 100:1.5 - 2.5:0.3 - 0.6:0.5 - 1.0. Among them, the nano-zinc oxide is pre-treated with a 5% mass fraction of stearic acid ethanol solution, and the treatment conditions are a solid-liquid ratio of 1:10, and ultrasonic dispersion is carried out at 60 °C for 30 minutes; the mixed material is added to a twin-screw extruder, and the temperatures of each section of the extruder are controlled as follows: the feeding section is 160 - 170 °C, the melting section is 180 - 190 °C, the reaction section is 200 - 210 °C, the extrusion section is 190 - 200 °C, the screw speed is 200 - 250 rpm, and the reaction time is 3 - 5 minutes; after the extrudate is cooled and granulated by water, it is dried in a vacuum drying oven at 50 °C for 8 - 10 hours to obtain maleic anhydride grafted polyethylene;

[0048] The nano-montmorillonite is prepared by the following steps:

[0049] The original nano-montmorillonite soil is mixed with deionized water according to a mass ratio of 1:8 - 1:12, and the stirring rate is 300 - 500 rpm for dispersion for 20 - 30 minutes. Then, γ-aminopropyltriethoxysilane with a mass fraction of 1 - 3% is added, and stirring reaction is carried out at 50 - 60 °C for 2 - 3 hours to graft the silane coupling agent onto the surface of the montmorillonite through chemical bonding; after the reaction, suction filtration is carried out, and it is washed with deionized water until the filtrate is clear, and the solid is dried to constant weight at 80 - 90 °C to obtain nano-montmorillonite.

[0050] The present invention has at least the following beneficial effects:

[0051] Through the synergistic effect of components such as fatty acid amide, polyoxyethylene ether surfactant, zinc octoate, and epoxidized soybean oil in the composite warm mix additive, the viscosity of asphalt is effectively reduced, and the discharge temperature is stably controlled at 72 - 85 °C, which is 30 - 40 °C lower than the traditional process, significantly reducing the heating energy consumption and construction cost.

[0052] The present invention uses diatomite as the core odor remover. Its porous structure can adsorb odor components such as hydrocarbons and sulfur volatilized from asphalt. When used in combination with activated carbon, zeolite molecular sieve, and amphiphilic surfactant, it can synergistically adsorb odor substances with different molecular sizes. Moreover, through processes such as hydrochloric acid pretreatment of diatomite, loading of iron oxide on activated carbon, and pore size regulation of zeolite molecular sieve, the capture efficiency for complex odor components is further improved, improving the construction environment and protecting the health of workers.

[0053] The present invention adds styrene - butadiene block copolymer, maleic anhydride - grafted polyethylene, and nano - montmorillonite to the modifier, combined with limestone powder modified by stearic acid and modified bentonite treated by organic modification and silane coupling, significantly improving the high - temperature stability, low - temperature crack resistance, anti - aging performance, and adhesion of asphalt. The addition of nano - graphene oxide can also improve the microscopic structure of asphalt, enhancing its strength, toughness, and ability to adapt to complex environments.

[0054] The present invention uses two - stage heating for the matrix asphalt and combines it with multi - stage stirring to ensure the uniform dispersion of each component in the asphalt. Through double - layer gradient filter screens to filter impurities and two - stage gradient cooling to control the asphalt curing process, it avoids quality problems caused by local overheating, uneven component dispersion, and sudden temperature changes, ensuring the stability of the product.

[0055] The low - temperature construction of the present invention reduces the emission of asphalt fumes, the odor remover adsorbs odors, and environmentally friendly materials such as epoxidized soybean oil and natural diatomite are selected, which conforms to the concept of green construction. At the same time, it has reduced energy consumption, improved construction efficiency, and reduced road maintenance costs, with significant comprehensive economic benefits.

[0056] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Detailed Description of the Invention

[0057] The following further elaborates on the present invention in conjunction with examples, so that those skilled in the art can implement it with reference to the text of the specification.

[0058] It should be noted that the experimental methods described in the following implementation examples are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0059] The present invention provides a preparation method for warm - mix odor - free asphalt, including the following steps:

[0060] After heating the base asphalt to 140 - 150 °C, a composite warm mix additive and an odorless agent are added to the base asphalt, and then a spiral stirrer is used to stir at a speed of 180 - 220 revolutions per minute for 20 - 30 minutes to form a first mixture; wherein, the composite warm mix additive includes fatty acid amide, polyoxyethylene ether surfactant, zinc octoate, and epoxidized soybean oil, and the mass ratio of the four is 2.8 - 3.2:0.9 - 1.1:0.4 - 0.6:0.2 - 0.4; the addition amount of the composite warm mix additive is 0.7 - 1.3% of the mass of the base asphalt; the odorless agent includes diatomite, and the addition amount of the odorless agent is 0.5 - 0.9% of the mass of the base asphalt;

[0061] After cooling the first mixture to 118 - 132 °C, a modifier is added, and then the spiral stirrer is maintained at a speed of 180 - 220 revolutions per minute and continues to stir for 30 - 40 minutes to form a second mixture; wherein, the modifier contains styrene - butadiene block copolymer, and the total mass of the modifier is 3.5 - 6.5% of the mass of the base asphalt; after cooling the first mixture to 118 - 132 °C, adding the modifier is to prevent the modifier from decomposing at high temperature and improve compatibility.

[0062] Mineral filler is added to the second mixture, and then the temperature is maintained at 118 - 132 °C and stirred for 12 - 18 minutes to form a third mixture; wherein, the mineral filler is composed of limestone powder and modified bentonite, and the mass ratio of the two is 6.5 - 7.5:0.8 - 1.2, and the addition amount of the mineral filler is 4.5 - 7.5% of the total mass of the base asphalt, composite warm mix additive, odorless agent, and modifier;

[0063] After cooling the third mixture to 72 - 85 °C, it is discharged.

[0064] When preparing warm mix odorless asphalt, first heat the base asphalt. Common petroleum base asphalt can be selected and put into a heating device. The heating device can choose an industrial heating furnace that can accurately control the temperature, and heat the base asphalt from room temperature to 140 - 150 °C, for example, set to heat to 145 °C. This heating process requires precise control of the temperature, which is achieved by adjusting the power of the heating furnace.

[0065] After heating to the specified temperature, add the composite warm mix agent and deodorizer to the base asphalt. The composite warm mix agent is composed of fatty acid amide, polyoxyethylene ether surfactant, zinc octanoate and epoxy soybean oil. Their mass ratio is between 2.8-3.2:0.9-1.1:0.4-0.6:0.2-0.4. The ratio of 3:1:0.5:0.3 can be selected. The amount added is 0.7-1.3% of the mass of the base asphalt, for example, the amount added is 1%. The deodorizer uses diatomaceous earth, and the amount of the deodorizer added is 0.5-0.9% of the mass of the base asphalt, assuming 0.7%. These materials can be purchased from the chemical raw material market. After adding, use a spiral stirrer to stir. The spiral stirrer can be selected from the market. The equipment that can reach a speed of 180-220 rpm is stirred at a speed of 200 rpm for 20-30 minutes, such as stirring for 25 minutes, to form a first mixture, so that the components are initially mixed evenly.

[0066] Next, the first mixture is cooled to 118-132°C, for example, to 125°C, and a modifier is added. The modifier contains styrene-butadiene block copolymer, and the addition amount is 3.5-6.5% of the mass of the base asphalt, and the addition amount can be selected to be 5%. The spiral stirrer is continued to be stirred at a speed of 180-220 rpm for 30-40 minutes, such as stirring for 35 minutes, to form a second mixture.

[0067] Then, a mineral filler is added to the second mixture, the mineral filler is composed of limestone powder and modified bentonite, the mass ratio is 6.5-7.5:0.8-1.2, for example 7:1, and the addition amount is 4.5-7.5% of the total mass of the base asphalt, the composite warm mix agent, the deodorant and the modifier, for example, the addition amount is 6%. The temperature is maintained at 118-132° C. and stirred for 12-18 minutes, for example, 15 minutes, to form a third mixture.

[0068] Finally, the third mixture is cooled to 72-85°C, for example, cooled to 80°C before being discharged.

[0069] Among them, fatty acid amide and polyoxyethylene ether surfactants as surfactants can reduce the asphalt-air interface tension, reduce the friction resistance in the asphalt mortar, and reduce the melt viscosity; zinc octanoate as a catalyst can adjust the chemical reaction activity of the polar components in the asphalt and promote the cross-linking compatibility between the warm mix agent and the asphalt molecules; Epoxidized soybean oil as a plasticizer can improve the low-temperature toughness of asphalt and enhance the mutual solubility between the components; the four can maintain good fluidity of asphalt at low temperatures through the synergistic effect of "interface activation-catalytic cross-linking-plasticization compatibility", and the discharge temperature can be reduced to 72-85℃;

[0070] Diatomite has a porous aluminosilicate structure (silicon dioxide content ≥ 85%, specific surface area 30-50m 2 / g), capture odor molecules such as hydrocarbons and sulfur volatilized from asphalt through physical adsorption. The hydroxyl groups on its surface form hydrogen bonds with the polar components of asphalt, enhancing the adsorption stability and reducing odor emissions during construction;

[0071] SBS forms an elastic network structure in asphalt, improving the high-temperature rutting resistance and low-temperature crack resistance;

[0072] The mineral filler composed of limestone powder and modified bentonite. The former provides a rigid skeleton, and the latter enhances the adhesion at the asphalt-filler interface through the interlayer swelling effect. The two work together to fill the voids in the asphalt mortar, improving the aggregate wrapping and overall strength.

[0073] The above preparation method can effectively reduce the construction temperature of asphalt, showing an obvious temperature reduction effect compared with the traditional process. At the same time, the odor remover can adsorb the odors volatilized from asphalt, improving the construction environment. Moreover, through multi-stage stirring and temperature control, the components are evenly dispersed, enhancing the stability and road performance of asphalt, and better meeting the requirements of road construction.

[0074] In another scheme, in the preparation method of the warm mix and odorless asphalt, the composite warm mix agent meets the following physical and chemical parameters: the carbon chain length of the fatty acid amide is C16 - C18, and the saponification value is 170 - 210 mgKOH / g; the polyoxyethylene ether surfactant is fatty alcohol polyoxyethylene ether, with an HLB value of 11.5 - 14.5 and an ethylene oxide addition number of 7 - 11; the zinc content of zinc octoate is 10 - 16%, calculated as the mass percentage of zinc element in zinc octoate; the hydroxyl value of epoxy soybean oil is 38 - 52 mgKOH / g;

[0075] The silicon dioxide content of diatomite is ≥85%, calculated as the mass percentage of silicon dioxide in diatomite, and the specific surface area is 30 - 50 m 2 / g;

[0076] The mass ratio of the composite warm mix agent to the odor remover is 1.4:1 - 2.6:1;

[0077] The styrene content of the styrene-butadiene block copolymer is 28 - 37%;

[0078] The calcium carbonate content of the limestone powder is ≥90%, and the particle size is ≤0.075 mm.

[0079] Each component of the composite warm mix additive has specific physical and chemical parameter requirements. The carbon chain length of the fatty acid amide is C16 - C18, for example, C17 can be selected; the saponification value is 170 - 210 mgKOH / g, such as 190 mgKOH / g. The polyoxyethylene ether surfactant is fatty alcohol polyoxyethylene ether, with an HLB value of 11.5 - 14.5, 13 can be selected; the ethylene oxide addition number is 7 - 11, for example, 9 is selected. The zinc content of zinc octoate is 10 - 16% by mass percentage of zinc element in zinc octoate, such as 13% is selected. The hydroxyl value of epoxidized soybean oil is 38 - 52 mgKOH / g, for example, 45 mgKOH / g is selected. Products meeting the corresponding parameters of these materials can be purchased in the chemical market.

[0080] The silicon dioxide content of diatomaceous earth ≥ 85%, and the specific surface area is 30 - 50 m 2 / g. Commercially available diatomaceous earth products meeting this condition can be selected. The mass ratio of the composite warm mix additive to the odor remover is 1.4:1 - 2.6:1, for example, 2:1. The styrene content of the styrene-butadiene block copolymer is 28 - 37%, and products with corresponding contents on the market can be selected. The calcium carbonate content of limestone powder ≥ 90%, and the particle size ≤ 0.075 mm. Existing limestone powder products meeting this standard can be selected.

[0081] Strictly controlling these parameters and material selections further optimizes the performance of warm mix odorless asphalt. The composite warm mix additive can more effectively reduce the viscosity of asphalt and enhance the warm mix effect. At the same time, the synergistic effect between components is better, improving the stability of asphalt, enabling it to maintain good performance under different environmental conditions and meeting the higher quality requirements for asphalt materials in road construction.

[0082] Among them, the fatty acid amide (C16 - C18 carbon chain, saponification value 170 - 210 mgKOH / g) and polyoxyethylene ether (HLB value 11.5 - 14.5, ethylene oxide addition number 7 - 11) form a gradient interfacial activity combination. The former enhances the affinity of polar groups in asphalt, and the latter adjusts the micelle structure through hydrophilic-hydrophobic segments to optimize the emulsification efficiency; zinc octoate (zinc content 10 - 16%) and epoxidized soybean oil (hydroxyl value 38 - 52 mgKOH / g) stabilize the dispersion state of the warm mix additive in asphalt through metal ion coordination and hydroxyl esterification reactions, avoiding delamination failure; the porous structure of diatomaceous earth provides a dispersion carrier for the warm mix additive. The acidic sites on its surface form chemical adsorption with the polar groups of the warm mix additive, preventing the warm mix additive from volatilizing and losing at high temperatures. At the same time, the warm mix additive reduces the viscosity of asphalt, making it easier for diatomaceous earth to embed into the asphalt colloid and improving the odor adsorption efficiency.

[0083] In another solution, in the preparation method of the warm mix and odorless asphalt, the modifier further includes maleic anhydride grafted polyethylene and nano-montmorillonite, and the mass ratio of the three is styrene-butadiene block copolymer: maleic anhydride grafted polyethylene: nano-montmorillonite = 1:0.5:0.3, and the total addition amount of the modifier is 3.5-6.5% of the mass of the base asphalt.

[0084] When the modifier further includes maleic anhydride grafted polyethylene and nano-montmorillonite, their mass ratio to the styrene-butadiene block copolymer is 1:0.5:0.3. The styrene-butadiene block copolymer, maleic anhydride grafted polyethylene and nano-montmorillonite can all choose products on the market that meet the mass ratio requirements. The total addition amount of the modifier is 3.5-6.5% of the mass of the base asphalt. During actual operation, it is necessary to accurately calculate the addition amount of each component according to the amount of the base asphalt.

[0085] Adding maleic anhydride grafted polyethylene and nano-montmorillonite and strictly controlling their ratio to the styrene-butadiene block copolymer significantly improves the performance of the asphalt. It enhances the flexibility and strength of the asphalt and improves its ability to resist external force deformation. At the same time, it also improves the anti-aging performance of the asphalt, extends the service life of the asphalt in road use, and enables the warm mix and odorless asphalt to better play its role in road construction.

[0086] In another solution, in the preparation method of the warm mix and odorless asphalt, the heating process of the base asphalt is carried out in two stages:

[0087] In the first stage, the base asphalt is heated from room temperature to 125-135°C at a heating rate of 4-6°C per minute and kept at this temperature for 10-15 minutes;

[0088] In the second stage, it is continuously heated to 140-150°C at a heating rate of 2-3°C per minute, and after reaching the target temperature, the composite warm mix agent and the odorless agent are added.

[0089] The heating process of the base asphalt is carried out in two stages. In the first stage, using an industrial heating furnace with a temperature control device, the base asphalt is heated from room temperature at a heating rate of 4-6°C per minute. For example, the heating rate is set to 5°C per minute and heated to 125-135°C, such as heated to 130°C, and kept at this temperature for 10-15 minutes, and the constant temperature time is selected as 12 minutes. The heating rate and the constant temperature time are controlled by adjusting the power of the heating furnace. This stage can make the base asphalt initially heated evenly and avoid the adverse effects of rapid heating on its performance.

[0090] In the second stage, continue to heat at a heating rate of 2-3 °C per minute, for example, the heating rate is 2.5 °C per minute, until the target temperature of 140-150 °C is reached. After reaching the target temperature, add the compound warm mix additive and the odorless agent. This two-stage heating method can make the matrix asphalt heat more evenly and create better conditions for the subsequent mixing with other components.

[0091] Two-stage heating (heating from 4-6 °C / min to 125-135 °C and keeping it constant for 10-15 min; heating from 2-3 °C / min to 140-150 °C): In the first stage, quickly heat to the asphalt softening point (about 120-130 °C) to preliminarily melt and homogenize the asphalt; in the constant temperature stage, eliminate the internal temperature gradient to avoid the volatilization of light components caused by local overheating; in the second stage, slowly heat to the reaction temperature to reduce the oxidation and degradation of the asphalt, provide a stable medium for the uniform dispersion of the subsequent warm mix additive and odorless agent, and prevent the overall compatibility from being affected by the performance fluctuations of the matrix asphalt.

[0092] This two-stage heating method improves the quality of the matrix asphalt, making it more fully blend with components such as the compound warm mix additive and the odorless agent in the subsequent process. It ensures the uniform dispersion of each component in the asphalt, thereby improving the overall performance of the warm mix odorless asphalt, reducing quality problems caused by temperature changes, and improving the stability of the product.

[0093] In another solution, in the preparation method of the warm mix odorless asphalt, before the third mixture is cooled, it needs to be filtered. The filtration treatment specifically includes the following steps:

[0094] Adopt a double-layer gradient filter screen. The upper layer is a corrugated stainless steel filter screen with a pore size of 2.5-3.0 mm, and the lower layer is a plain woven galvanized filter screen with a pore size of 2.0-2.5 mm; control the filtration pressure to be 0.15-0.25 MPa, and pre-coat the surface of the filter screen with a nano-silica anti-sticking layer with a mass fraction of 0.5-1.0%; control the discharge temperature after filtration to be 108-117 °C;

[0095] The cooling method is specifically as follows:

[0096] Cool the filtered asphalt in two stages. In the first stage, cool from 108-117 °C to 95-100 °C at a rate of 3.0-3.5 °C per minute for 5-8 minutes; in the second stage, cool from 95-100 °C to 72-85 °C at a rate of 2.0-2.5 °C per minute for 12-15 minutes.

[0097] Before the third mixture is cooled, it needs to be filtered. During filtration, a double-layer gradient filter screen is used. The upper layer can be a corrugated stainless steel filter screen with a pore size of 2.5 - 3.0 mm, and the lower layer can be a plain-woven galvanized filter screen with a pore size of 2.0 - 2.5 mm. These filter screens can be purchased on the market. The filtration pressure is controlled at 0.15 - 0.25 MPa, for example, controlled at 0.2 MPa. A nano-silica anti-sticking layer with a mass fraction of 0.5 - 1.0% is pre-coated on the surface of the filter screen. Nano-silica products meeting the requirements on the market can be selected. The discharge temperature is controlled at 108 - 117 °C, for example, controlled at 112 °C. The filter screen is installed at the front end of the discharge port and is used to filter impurities in the mixture.

[0098] The cooling method is divided into two stages. In the first stage, it is cooled from 108 - 117 °C to 95 - 100 °C at a rate of 3.0 - 3.5 °C per minute, for example, cooled from 112 °C to 98 °C, and lasts for 5 - 8 minutes, such as lasting for 6 minutes; in the second stage, it is cooled from 95 - 100 °C to 72 - 85 °C at a rate of 2.0 - 2.5 °C per minute, for example, cooled from 98 °C to 82 °C, and lasts for 12 - 15 minutes, such as lasting for 13 minutes.

[0099] Double-layer gradient filter screen (upper layer 2.5 - 3.0 mm corrugated stainless steel, lower layer 2.0 - 2.5 mm plain-woven galvanized) and nano-silica anti-sticking layer: The upper filter screen removes large particle impurities, the lower filter screen intercepts fine particles, and pre-coated nano-silica reduces asphalt adhesion, ensuring pure discharge; Gradient cooling (first stage 3.0 - 3.5 °C / min to 95 - 100 °C, second stage 2.0 - 2.5 °C / min to 72 - 85 °C) avoids the destruction of the asphalt colloid structure caused by sudden temperature changes. The first stage quickly solidifies to form a preliminary skeleton, and the second stage slowly cools to promote the full cross-linking of the modifier and asphalt molecules, improving the overall stability.

[0100] Through filtration treatment, impurities in the mixture can be removed, ensuring the purity of asphalt. A reasonable cooling method can enable asphalt to maintain good performance during the cooling process, avoiding affecting the quality of asphalt due to too fast or too slow cooling. The quality of warm mix odorless asphalt is improved, making it more in line with the usage standards for road construction.

[0101] The interception efficiency of the double-layer filter screen reaches 99.5% (for particles > 1 mm), and the nano anti-sticking layer extends the filter screen cleaning cycle to more than 50 batches. Staged cooling avoids the generation of micro-cracks due to rapid shrinkage of asphalt. The final product has no visible particles, and the ductility at 25 °C ≥ 100 cm.

[0102] In another solution, in the preparation method of the warm mix odorless asphalt, before the limestone powder is used, it is pretreated through the following steps:

[0103] Impregnate limestone powder in a stearic acid ethanol solution with a mass fraction of 3 - 5% at a solid-liquid mass ratio of 1:3 - 1:5, ultrasonically treat it at 80 - 90 °C for 20 - 30 minutes, with an ultrasonic power density of 0.5 - 0.8 W / mL and a frequency of 40 - 60 kHz; after treatment, centrifuge and separate, with a centrifuge speed of 3000 - 4000 rpm and a time of 10 - 15 minutes, and vacuum-dry the solid product at 60 - 70 °C for 2 - 3 hours;

[0104] The modified bentonite is prepared through the following steps:

[0105] Mix bentonite with deionized water at a mass ratio of 1:10 - 1:15, add cetyltrimethylammonium bromide, with an addition amount of 15 - 20% of the dry basis mass of bentonite, stir and react at 50 - 60 °C for 4 - 6 hours, so that cetyltrimethylammonium bromide enters the interlayer of bentonite through ion exchange to form an organic modified layer, after the reaction, filter by suction and wash with water until there are no free bromide ions in the filtrate, and dry the solid to constant weight at 80 - 90 °C to obtain organic bentonite;

[0106] Mix the above-prepared organic bentonite with a γ-aminopropyltriethoxysilane ethanol solution with a mass fraction of 2 - 4% at a solid-liquid mass ratio of 1:5 - 1:8, ultrasonically treat it at 60 - 70 °C for 30 - 40 minutes, after treatment, centrifuge and separate, and vacuum-dry the solid at 60 - 70 °C for 2 - 3 hours to obtain modified bentonite.

[0107] Limestone powder needs to be pretreated before use. Impregnate limestone powder in a stearic acid ethanol solution with a mass fraction of 3 - 5% at a solid-liquid mass ratio of 1:3 - 1:5, for example 1:4. The solution can be prepared with stearic acid and ethanol available on the market. Ultrasonically treat it at 80 - 90 °C for 20 - 30 minutes, with an ultrasonic power density of 0.5 - 0.8 W / mL and a frequency of 40 - 60 kHz. Use an ultrasonic device that can meet this ultrasonic condition, and place the probe of the ultrasonic device into the container containing limestone powder and the solution for treatment. After treatment, centrifuge and separate, with a centrifuge speed of 3000 - 4000 rpm and a time of 10 - 15 minutes. Use a suitable centrifuge, and vacuum-dry the solid product at 60 - 70 °C for 2 - 3 hours. Use a vacuum drying oven for drying.

[0108] When preparing modified bentonite, first mix bentonite with deionized water at a mass ratio of 1:10 - 1:15, add cetyltrimethylammonium bromide, and its addition amount is 15 - 20% of the dry basis mass of bentonite. Stir and react at 50 - 60 °C for 4 - 6 hours. After the reaction, filter by suction and wash with water until there are no free bromide ions in the filtrate. Dry the solid at 80 - 90 °C to constant weight to obtain organic bentonite. Then mix the organic bentonite with a 2 - 4% mass fraction of γ-aminopropyltriethoxysilane ethanol solution at a solid-liquid mass ratio of 1:5 - 1:8, perform ultrasonic treatment at 60 - 70 °C for 30 - 40 minutes, centrifuge and separate after treatment, and vacuum dry the solid at 60 - 70 °C for 2 - 3 hours to obtain modified bentonite. These materials can all be selected from existing products on the market.

[0109] Modification of limestone powder with stearic acid: Stearic acid (C18 fatty acid) coats the surface of limestone powder (CaCO3) through an esterification reaction, with the hydrophobic group facing the asphalt, enhancing the compatibility with the asphalt, reducing water adsorption, and improving the filler-asphalt interfacial adhesion.

[0110] Preparation of modified bentonite (organic modification with cetyltrimethylammonium bromide + silane coupling): Cetyltrimethylammonium bromide enters the interlayer of bentonite through ion exchange, expanding the layer spacing (from 1.2 nm to more than 2.5 nm) to form an oleophilic modified layer; after grafting with γ-aminopropyltriethoxysilane, the alkoxy groups of the silane coupling agent condense with the hydroxyl groups on the surface of bentonite, and the amino groups react with the polar groups of the asphalt, causing the bentonite to be exfoliated and dispersed in the asphalt, having the dual functions of adsorbing odors and enhancing mechanical properties.

[0111] Pretreating and modifying limestone powder and bentonite can improve their compatibility with asphalt, make the mineral filler disperse more evenly in the asphalt, enhance the adhesiveness and stability of the asphalt, improve the use effect of warm mix and odorless asphalt in road construction, enable it to work better with other components, and improve the quality of the road.

[0112] Coating with stearic acid increases the contact angle of limestone powder from 30° to 110°, improving its compatibility with asphalt; the interlayer spacing of organic bentonite expands from 1.2 nm to 2.8 nm, and the dispersion uniformity of the modified mineral filler in the asphalt increases by 40%.

[0113] In another scheme, in the preparation method of the warm mix and odorless asphalt, the composite warm mix agent further includes nano-graphene oxide, and the addition amount of nano-graphene oxide is 0.1 - 0.3% of the total mass of the composite warm mix agent; the total addition amount of the composite warm mix agent is 0.7 - 1.3% of the mass of the matrix asphalt.

[0114] The preparation method of the nano-graphene oxide is as follows:

[0115] Add natural graphite powder to the mixed acid of concentrated sulfuric acid and concentrated phosphoric acid, where the volume ratio of concentrated sulfuric acid to concentrated phosphoric acid is 9:1. Stir for 30 minutes under ice bath conditions, and then slowly add potassium permanganate. The mass ratio of potassium permanganate to graphite powder is 6:1. Control the reaction temperature not to exceed 20 °C and stir for 2 hours; heat the reaction system to 50 °C and continue stirring for 12 hours. Then slowly pour the reaction solution into ice water, and at the same time add 30% hydrogen peroxide solution by mass until the solution color turns bright yellow. Stir evenly and let it stand for precipitation;

[0116] Wash the precipitate with deionized water repeatedly until it is neutral, then carry out centrifugal separation. Vacuum dry the obtained solid at 60 °C for 24 hours to obtain graphene oxide;

[0117] Disperse graphene oxide in absolute ethanol to form a graphene oxide dispersion with a mass fraction of 0.5-1%. Add the amino silane coupling agent γ-aminopropyltriethoxysilane to it, and its addition amount is 1-2% of the mass of graphene oxide. Carry out reflux stirring reaction at 80 °C for 6 hours to cause the amino silane coupling agent to undergo a condensation reaction with the hydroxyl groups on the surface of graphene oxide to form a grafted modification layer; after the reaction is completed, carry out centrifugal separation on the product, wash it with absolute ethanol for many times, and then vacuum dry it at 60 °C for 12 hours to obtain nano-graphene oxide grafted with amino silane coupling agent;

[0118] The dispersion treatment steps of the nano-graphene oxide are as follows:

[0119] Take 1 / 3-1 / 2 of the total mass of epoxidized soybean oil in the composite warm mix additive and nano-graphene oxide and add them to the reaction vessel. Carry out ultrasonic treatment at 50-60 °C, with an ultrasonic frequency of 40-60 kHz and a power density of 0.3-0.5 W / mL, and a treatment time of 10-15 minutes to uniformly disperse the nano-graphene oxide in this part of epoxidized soybean oil;

[0120] Subsequently, continue ultrasonic treatment for 5-8 minutes to cause the amino silane coupling agent to undergo a condensation reaction with the hydroxyl groups on the surface of the nano-graphene oxide to form a grafted modification layer, and obtain a pre-dispersed nano-graphene oxide mixture;

[0121] Mix the remaining epoxidized soybean oil with fatty acid amide, polyoxyethylene ether surfactant, and zinc octoate, and add them to the matrix asphalt synchronously with the above-mentioned pre-dispersed nano-graphene oxide mixture. Control the rotation speed of the spiral stirrer to be 200-220 revolutions per minute and the shear rate ≥600 s-1, and continuously stir for 8-10 minutes to make the nano-graphene oxide uniformly disperse in the asphalt system through the action of mechanical shear force.

[0122] The composite warm mix additive can also be added with nano-graphene oxide, and the addition amount is 0.1-0.3% of the total mass of the composite warm mix additive, for example, 0.2% is added. When preparing nano-graphene oxide, first add natural graphite powder into the mixed acid of concentrated sulfuric acid and concentrated phosphoric acid. The volume ratio of concentrated sulfuric acid to concentrated phosphoric acid is 9:1. Stir for 30 minutes under ice bath conditions, and then slowly add potassium permanganate. The mass ratio of potassium permanganate to graphite powder is 6:1. Control the reaction temperature not to exceed 20°C and stir for 2 hours; raise the temperature to 50°C and continue to stir for 12 hours. Pour into ice water and add hydrogen peroxide solution with a mass fraction of 30% until the color becomes bright yellow. Let it stand for precipitation, wash, centrifuge, and dry to obtain graphene oxide. Then disperse the graphene oxide in anhydrous ethanol to form a dispersion with a mass fraction of 0.5-1%, and add the amino silane coupling agent γ-aminopropyltriethoxysilane. The addition amount is 1-2% of the mass of graphene oxide. Reflux and stir at 80°C for 6 hours, and then obtain nano-graphene oxide grafted with amino silane coupling agent on the surface through centrifugation, washing, and drying. All these materials can be bought in the chemical raw material market.

[0123] When dispersing and treating nano-graphene oxide, take 1 / 3-1 / 2 of the total mass of epoxidized soybean oil in the composite warm mix additive, for example, 1 / 2, and add it to the reaction vessel together with nano-graphene oxide. Perform ultrasonic treatment at 50-60°C, with an ultrasonic frequency of 40-60 kHz and a power density of 0.3-0.5 W / mL. Treat for 10-15 minutes, then continue ultrasonic treatment for 5-8 minutes. Then mix the remaining epoxidized soybean oil with other components of the composite warm mix additive and synchronously add them to the matrix asphalt. Control the rotation speed of the screw stirrer at 220-250 revolutions per minute and the shear rate ≥600 s-1, and stir for 8-10 minutes. Equipment used in these operations, such as ultrasonic equipment and screw stirrers, can all select existing products on the market.

[0124] Adding nano-graphene oxide and dispersing it reasonably can further improve the performance of the composite warm mix additive. It enhances the strength and toughness of the asphalt, improves the microstructure of the asphalt, makes it perform better in resisting vehicle loads and environmental factors, improves the road performance of warm mix odorless asphalt, and extends the service life of the road. After the nano-graphene oxide is modified with amino silane, amino groups are grafted on the surface, forming hydrogen bonds with the hydroxyl groups of epoxidized soybean oil, and are uniformly dispersed in the asphalt through the "ultrasonic dispersion-mechanical shear" process; its two-dimensional sheet structure (specific surface area ≥500m 2 / g) adsorbs asphalt molecules to form a "nano-enhanced network". While synergistically reducing the viscosity of the warm mix additive, it improves the tensile strength and fatigue resistance of the asphalt. A trace addition of 0.1-0.3% can significantly improve the microstructure.

[0125] In another solution, in the preparation method of the warm mix odorless asphalt, the odorless agent further includes activated carbon, zeolite molecular sieve, and amphiphilic surfactant. The mass ratio of diatomite, activated carbon, zeolite molecular sieve, and amphiphilic surfactant is 5:3:1:0.5; the total addition amount of the odorless agent is 0.5-0.9% of the mass of the matrix asphalt;

[0126] The diatomite was pretreated before use, and its pretreatment method is as follows:

[0127] The diatomite was impregnated in a hydrochloric acid solution with a mass fraction of 5-8%, the solid-liquid ratio was 1:4-1:6, and it was stirred at 60-70 °C for 1-2 hours to remove impurities, and then washed with water to neutrality and dried;

[0128] The activated carbon was pretreated before use, and its pretreatment method is as follows:

[0129] The activated carbon was activated at 600-700 °C for 1-1.5 hours under nitrogen protection, cooled and impregnated with a ferric nitrate solution with a mass fraction of 1-2%, the solid-liquid ratio was 1:3-1:5, and after drying, iron oxide was loaded, and the content of Fe3O4 was 3-5% of the mass of the activated carbon;

[0130] The zeolite molecular sieve was pretreated before use, and its pretreatment method is as follows:

[0131] The zeolite molecular sieve was mixed with an aqueous solution of cetyltrimethylammonium bromide with a mass fraction of 2-4% according to a solid-liquid ratio of 1:5-1:8, and reacted at 80-90 °C for 3-4 hours for ion exchange to adjust the pore size to 0.5-0.8 nm;

[0132] The amphiphilic surfactant uses a polyethylene glycol-polypropylene glycol block copolymer, its molecular weight is 2000-3000, and the HLB value is 14-16.

[0133] The four components (diatomite: activated carbon: zeolite molecular sieve: amphiphilic surfactant = 5:3:1:0.5) need to be uniformly mixed in advance according to the mass ratio to form a composite odorless agent system.

[0134] In addition to diatomite, the odorless agent also includes activated carbon, zeolite molecular sieve, and amphiphilic surfactant, and their mass ratio is 5:3:1:0.5. Before using the diatomite, it was impregnated in a hydrochloric acid solution with a mass fraction of 5-8%, the solid-liquid ratio was 1:4-1:6. For example, a hydrochloric acid solution with a mass fraction of 6% was selected, the solid-liquid ratio was 1:5, and it was stirred at 60-70 °C for 1-2 hours, such as stirring for 1.5 hours to remove impurities, and then washed with water to neutrality and dried. The diatomite can select products on the market with a silica content ≥ 85% and a specific surface area of 30-50 m 2 / g.

[0135] Before use, the activated carbon needs to be activated at 600 - 700 °C for 1 - 1.5 hours under nitrogen protection, for example, activated at 650 °C for 1.2 hours. After cooling, it is impregnated with a ferric nitrate solution with a mass fraction of 1 - 2%, and the solid-liquid ratio is 1:3 - 1:5, such as 1:4. After drying, iron oxide is loaded, and the content of Fe3O4 is 3 - 5% of the mass of the activated carbon. The activated carbon can be selected from common products on the market with good adsorption properties. Before use, the zeolite molecular sieve is mixed with an aqueous solution of cetyltrimethylammonium bromide with a mass fraction of 2 - 4% according to a solid-liquid ratio of 1:5 - 1:8. For example, a solution with a mass fraction of 3% is selected, and the solid-liquid ratio is 1:6. It reacts at 80 - 90 °C for 3 - 4 hours for ion exchange to adjust the pore size to 0.5 - 0.8 nm. The amphiphilic surfactant uses a polyethylene glycol - polypropylene glycol block copolymer with a molecular weight of 2000 - 3000 and an HLB value of 14 - 16. Products meeting these parameters on the market can be selected.

[0136] Among them, diatomaceous earth (porous silica) adsorbs medium and large molecular odors (such as polycyclic aromatic hydrocarbons); activated carbon (microporous structure, loaded with Fe3O4) captures polar small molecules (such as mercaptans) through chemical adsorption; zeolite molecular sieve (pore size 0.5 - 0.8 nm) sieves and adsorbs ultra-small molecules (such as ammonia); the polyethylene glycol - polypropylene glycol block copolymer acts as an amphiphilic agent, its hydrophilic end connects to the polar adsorbent, and its hydrophobic end integrates into the asphalt, enhancing the compatibility of each odor-removing agent with the asphalt, forming a synergistic odor-removing mechanism of "pore size hierarchical adsorption - interfacial compatibility and stability".

[0137] Through the compounding of various odor-removing materials and their pretreatment, the odor components volatilized from the asphalt can be adsorbed more comprehensively. Different odor-removing materials play roles for different odor substances. Activated carbon mainly adsorbs large molecular odor substances, zeolite molecular sieve has a good adsorption effect on small molecular odor substances, diatomaceous earth adsorbs various odor components by virtue of its large specific surface area, and the amphiphilic surfactant enhances the compatibility of each odor-removing material with the asphalt. Finally, the odor generated during the construction and use of the asphalt is effectively reduced, and the construction environment and use experience are improved.

[0138] In another scheme, in the preparation method of the warm mix odor-removing asphalt, the maleic anhydride grafted polyethylene is prepared by the following melt grafting method:

[0139] Mix low-density polyethylene particles, maleic anhydride, diisopropylbenzene peroxide, and nano-zinc oxide in a mass ratio of 100:1.5 - 2.5:0.3 - 0.6:0.5 - 1.0. Among them, the nano-zinc oxide is pre-treated with a 5% stearic acid ethanol solution, and the treatment conditions are a solid-liquid ratio of 1:10, and ultrasonic dispersion at 60 °C for 30 minutes. Add the mixed material into a twin-screw extruder, and control the temperatures of each section of the extruder as follows: the feeding section is 160 - 170 °C, the melting section is 180 - 190 °C, the reaction section is 200 - 210 °C, the extrusion section is 190 - 200 °C, the screw speed is 200 - 250 rpm, and the reaction time is 3 - 5 minutes. After the extrudate is granulated by water cooling, it is dried in a vacuum drying oven at 50 °C for 8 - 10 hours to obtain maleic anhydride-grafted polyethylene.

[0140] The nano-montmorillonite is prepared through the following steps:

[0141] Mix the original nano-montmorillonite soil and deionized water in a mass ratio of 1:8 - 1:12, disperse at a stirring rate of 300 - 500 rpm for 20 - 30 minutes, add γ-aminopropyltriethoxysilane with a mass fraction of 1 - 3%, and stir and react at 50 - 60 °C for 2 - 3 hours to graft the silane coupling agent onto the surface of montmorillonite through chemical bonding. After the reaction, filter by suction, wash with deionized water until the filtrate is clear, and dry the solid at 80 - 90 °C to constant weight to obtain nano-montmorillonite.

[0142] Maleic anhydride-grafted polyethylene is prepared by the melt grafting method. Mix low-density polyethylene particles, maleic anhydride, diisopropylbenzene peroxide, and nano-zinc oxide in a mass ratio of 100:1.5 - 2.5:0.3 - 0.6:0.5 - 1.0. For example, a ratio of 100:2:0.5:0.8 can be selected. Among them, the nano-zinc oxide is pre-treated with a 5% stearic acid ethanol solution, and the treatment conditions are a solid-liquid ratio of 1:10, and ultrasonic dispersion at 60 °C for 30 minutes. These materials can all be purchased from the chemical raw material market. Add the mixed material into a twin-screw extruder, and the twin-screw extruder can select equipment on the market that can meet the processing requirements. Control the temperatures of each section of the extruder as follows: the feeding section is 160 - 170 °C, such as 165 °C; the melting section is 180 - 190 °C, such as 185 °C; the reaction section is 200 - 210 °C, for example 205 °C; the extrusion section is 190 - 200 °C, like 195 °C, the screw speed is 200 - 250 rpm, for example 220 rpm, the reaction time is 3 - 5 minutes, such as 4 minutes. After the extrudate is granulated by water cooling, it is dried in a vacuum drying oven at 50 °C for 8 - 10 hours, for example, dried for 9 hours, to obtain maleic anhydride-grafted polyethylene.

[0143] The nano-montmorillonite is prepared through the following steps: The original nano-montmorillonite soil is mixed with deionized water at a mass ratio of 1:8 - 1:12, such as 1:10, and dispersed for 20 - 30 minutes at a stirring rate of 300 - 500 rpm, for example, dispersed for 25 minutes at 400 rpm. Then, γ-aminopropyltriethoxysilane with a mass fraction of 1 - 3% is added, such as 2%. Stirring reaction is carried out at 50 - 60 °C for 2 - 3 hours, such as reacting for 2.5 hours, so that the silane coupling agent is grafted onto the surface of montmorillonite through chemical bonding. After the reaction, filtration is carried out, and it is washed with deionized water until the filtrate is clear. The solid is dried at 80 - 90 °C to constant weight, for example, dried at 85 °C, to obtain the nano-montmorillonite.

[0144] For the preparation of maleic anhydride grafted polyethylene, low-density polyethylene provides a flexible backbone. After maleic anhydride grafting, polar groups are introduced, forming ester bonds with asphalt carboxylic acids. Nano-zinc oxide (treated with stearic acid) is used as a crosslinking agent to promote the grafting reaction initiated by dicumyl peroxide, improve the grafting rate (≥1.5%), and enhance the chemical binding force between the polymer and asphalt.

[0145] For the preparation of nano-montmorillonite, γ-aminopropyltriethoxysilane is grafted onto the surface of montmorillonite. The amino group forms physical entanglement with the styrene segment of SBS, and the silane oxy group condenses with the montmorillonite hydroxyl group, enabling montmorillonite to be dispersed in a exfoliated state in asphalt, hindering the movement of asphalt molecular chains, and synergistically enhancing the high-temperature viscosity and anti-aging performance of asphalt with LLDPE-g-MAH.

[0146] Among them, the SBS elastic segment (polybutadiene) absorbs load stress, and the rigid segment (polystyrene) forms physical crosslinking points. Maleic anhydride grafted polyethylene forms ester bonds with asphalt carboxylic acids through anhydride groups, enhancing the compatibility between the polymer and asphalt. After the nano-montmorillonite is modified with silane, the layer spacing expands, and nano-sheets are formed by exfoliation in asphalt, hindering the movement of molecular chains and improving the high-temperature stability. The three achieve the "elastic toughening - interface bonding - nano-enhancement" synergistic effect, endowing asphalt with both high elasticity and anti-aging performance.

[0147] Example 1

[0148] The preparation method of warm mix odorless asphalt includes the following steps:

[0149] After heating the base asphalt to 145 °C, a composite warm mix agent and an odorless agent are added to the base asphalt, and then a spiral stirrer is used to stir at a speed of 210 revolutions per minute for 25 minutes to form a first mixture.

[0150] The composite warm mix agent includes fatty acid amide, polyoxyethylene ether surfactant, zinc octoate, and epoxidized soybean oil, and the mass ratio of the four is 3.0:1.0:0.5:0.3.

[0151] The addition amount of the composite warm mix agent is 1.0% of the mass of the base asphalt.

[0152] The odor-removing agent includes diatomite, and the addition amount of the odor-removing agent is 0.7% of the mass of the matrix asphalt;

[0153] After cooling the first mixture to 125°C, a modifier is added, and then the rotation speed of the screw agitator is maintained at 210 revolutions per minute and stirring continues for 35 minutes to form a second mixture;

[0154] The modifier contains a styrene-butadiene block copolymer, and its addition amount is 5.0% of the mass of the matrix asphalt;

[0155] Mineral filler is added to the second mixture, and then stirring is carried out at a temperature of 125°C for 15 minutes to form a third mixture;

[0156] The mineral filler is composed of limestone powder and modified bentonite, and the mass ratio of the two is 7.0:1.0;

[0157] The addition amount of the mineral filler is 6.0% of the total mass of the matrix asphalt, the composite warm mix agent, the odor-removing agent, and the modifier;

[0158] The third mixture is cooled and then discharged.

[0159] Example 2

[0160] On the basis of Example 1, the following content is added:

[0161] The composite warm mix agent meets the following physical and chemical parameters: the carbon chain length of the fatty acid amide is C17, and the saponification value is 190 mgKOH / g; the polyoxyethylene ether surfactant is fatty alcohol polyoxyethylene ether, the HLB value is 13.0, and the ethylene oxide addition number is 9; the zinc content of zinc octoate is 13%, calculated as the mass percentage of zinc element in zinc octoate; the hydroxyl value of epoxidized soybean oil is 45 mgKOH / g;

[0162] The silicon dioxide content of the diatomite ≥ 85%, calculated as the mass percentage of silicon dioxide in the diatomite, and the specific surface area is 40m 2 / g;

[0163] The styrene content of the styrene-butadiene block copolymer is 32.5%;

[0164] The calcium carbonate content of the limestone powder ≥ 90%, and the particle size ≤ 0.075 mm;

[0165] In the modifier, the mass ratio of the styrene-butadiene block copolymer: maleic anhydride grafted polyethylene: nano-montmorillonite is 1:0.5:0.3, and the total addition amount of the modifier is 5.0% of the mass of the matrix asphalt;

[0166] The heating process of the base asphalt is carried out in two stages:

[0167] In the first stage, the base asphalt is heated from room temperature to 130°C at a heating rate of 5°C per minute and kept at this temperature for 12.5 minutes;

[0168] In the second stage, it is continuously heated to 145°C at a heating rate of 2.5°C per minute, and after reaching the target temperature, a composite warm mix additive and a deodorant are added;

[0169] Before the third mixture is cooled, it needs to be filtered. The filtration process specifically includes the following steps:

[0170] A double-layer gradient filter screen is used. The upper layer is a corrugated stainless steel filter screen with a pore size of 2.7 mm, and the lower layer is a plain woven galvanized filter screen with a pore size of 2.2 mm; the filtration pressure is controlled at 0.20 MPa, and a nano-silica anti-sticking layer with a mass fraction of 0.75% is pre-coated on the surface of the filter screen; the discharging temperature after filtration is controlled at 112.5°C;

[0171] The cooling method is specifically as follows:

[0172] In the first stage, it is cooled from 112.5°C to 97.5°C at a rate of 3.25°C per minute for 6.5 minutes;

[0173] In the second stage, it is cooled from 97.5°C to 80°C at a rate of 2.25°C per minute for 13.5 minutes;

[0174] The maleic anhydride grafted polyethylene is prepared by the following melt grafting method:

[0175] Low-density polyethylene particles, maleic anhydride, diisopropylbenzene peroxide and nano-zinc oxide are mixed at a mass ratio of 100:2.0:0.45:0.75. Among them, the nano-zinc oxide is pre-treated with a 5% mass fraction of stearic acid ethanol solution under the condition of a solid-liquid ratio of 1:10 and ultrasonically dispersed at 60°C for 30 minutes; the mixed material is added to a twin-screw extruder, and the temperatures of each section of the extruder are controlled as follows: the feeding section is 165°C, the melting section is 185°C, the reaction section is 205°C, the extrusion section is 195°C, the screw speed is 225 rpm, and the reaction time is 4 minutes; after the extrudate is water-cooled and pelletized, it is dried in a vacuum drying oven at 50°C for 9 hours to obtain maleic anhydride grafted polyethylene;

[0176] The nano-montmorillonite is prepared by the following steps:

[0177] The nano-montmorillonite raw soil and deionized water are mixed at a mass ratio of 1:10, and dispersed at a stirring rate of 400 rpm for 25 minutes; 2% mass fraction of γ-aminopropyltriethoxysilane is added, and stirred and reacted at 55°C for 2.5 hours; after the reaction, it is filtered by suction, washed with deionized water until the filtrate is clear, and the solid is dried to constant weight at 85°C to obtain nano-montmorillonite.

[0178] Example 3

[0179] Based on Example 2, the following content is added:

[0180] Before use, the limestone powder is pretreated through the following steps:

[0181] The limestone powder is impregnated in a 4% stearic acid ethanol solution according to a solid-liquid mass ratio of 1:4, ultrasonically treated at 85 °C for 25 minutes, with an ultrasonic power density of 0.65 W / mL and a frequency of 50 kHz; after treatment, centrifugal separation is carried out at a centrifugal speed of 3500 rpm for 12.5 minutes, and the solid product is vacuum dried at 65 °C for 2.5 hours;

[0182] The modified bentonite is prepared through the following steps:

[0183] The bentonite and deionized water are mixed according to a mass ratio of 1:12.5, and cetyltrimethylammonium bromide is added, with an addition amount of 17.5% of the dry basis mass of the bentonite. Stirring reaction is carried out at 55 °C for 5 hours to enable cetyltrimethylammonium bromide to enter the interlayer of the bentonite through ion exchange to form an organic modified layer. After the reaction, suction filtration is carried out and washed with water until there are no free bromide ions in the filtrate, and the solid is dried to constant weight at 85 °C to obtain organic bentonite;

[0184] The above-prepared organic bentonite and a 3% γ-aminopropyltriethoxysilane ethanol solution are mixed according to a solid-liquid mass ratio of 1:6.5, ultrasonically treated at 65 °C for 35 minutes, and after treatment, centrifugal separation is carried out, and the solid is vacuum dried at 65 °C for 2.5 hours to obtain modified bentonite.

[0185] Example 4

[0186] Based on Example 3, the following content is added:

[0187] The composite warm mix additive further includes nano-graphene oxide, and the addition amount of nano-graphene oxide is 0.2% of the total mass of the composite warm mix additive; the total addition amount of the composite warm mix additive is 1% of the mass of the matrix asphalt;

[0188] The preparation method of the nano-graphene oxide is as follows:

[0189] Add natural graphite powder to the mixed acid of concentrated sulfuric acid and concentrated phosphoric acid, where the volume ratio of concentrated sulfuric acid to concentrated phosphoric acid is 9:1. Stir for 30 minutes under ice bath conditions, then slowly add potassium permanganate. The mass ratio of potassium permanganate to graphite powder is 6:1. Control the reaction temperature not to exceed 20 °C and stir for 2 hours; heat the reaction system to 50 °C and continue stirring for 12 hours. Then slowly pour the reaction solution into ice water and add 30% hydrogen peroxide solution by mass until the solution color turns bright yellow. Stir evenly and let it stand for precipitation;

[0190] Wash the precipitate with deionized water repeatedly until it is neutral, then perform centrifugal separation. Dry the obtained solid under vacuum at 60 °C for 24 hours to obtain graphene oxide;

[0191] Disperse graphene oxide in absolute ethanol to form a 0.75% graphene oxide dispersion by mass. Add the amino-silane coupling agent γ-aminopropyltriethoxysilane to it, and its addition amount is 1.5% of the mass of graphene oxide. Reflux and stir at 80 °C for 6 hours to cause a condensation reaction between the amino-silane coupling agent and the hydroxyl groups on the surface of graphene oxide to form a grafted modification layer; after the reaction, centrifuge the product, wash it with absolute ethanol multiple times, and then dry it under vacuum at 60 °C for 12 hours to obtain nano-graphene oxide grafted with amino-silane coupling agent;

[0192] The dispersion treatment steps of the nano-graphene oxide are as follows:

[0193] Take 1 / 2 of the total mass of epoxidized soybean oil in the composite warm mix additive and add nano-graphene oxide to the reaction vessel. Perform ultrasonic treatment at 55 °C, with an ultrasonic frequency of 50 kHz, a power density of 0.4 W / mL, and a treatment time of 12.5 minutes to uniformly disperse nano-graphene oxide in this part of epoxidized soybean oil;

[0194] Subsequently, continue ultrasonic treatment for 6.5 minutes to cause a condensation reaction between the amino-silane coupling agent and the hydroxyl groups on the surface of nano-graphene oxide to form a grafted modification layer, obtaining a pre-dispersed nano-graphene oxide mixture;

[0195] Mix the remaining epoxidized soybean oil with fatty acid amide, polyoxyethylene ether surfactant, and zinc octoate. And synchronously add it to the matrix asphalt with the above pre-dispersed nano-graphene oxide mixture. Control the rotation speed of the helical stirrer to be 210 revolutions per minute, and the shear rate ≥ 600 s-1. Continuously stir for 9 minutes to uniformly disperse nano-graphene oxide in the asphalt system through the action of mechanical shear force.

[0196] Example 5

[0197] On the basis of Example 4, add the following content:

[0198] The odor remover also includes activated carbon, zeolite molecular sieve, and amphiphilic surfactant. The mass ratio of diatomite, activated carbon, zeolite molecular sieve, and amphiphilic surfactant is 5:3:1:0.5. The total addition amount of the odor remover is 0.7% of the mass of the matrix asphalt.

[0199] The diatomite was pretreated before use, and the pretreatment method is as follows:

[0200] The diatomite was impregnated in a hydrochloric acid solution with a mass fraction of 6.5%, the solid-liquid ratio was 1:5, and it was stirred at 65 °C for 1.5 hours to remove impurities, and then washed with water until neutral and dried.

[0201] The activated carbon was pretreated before use, and the pretreatment method is as follows:

[0202] The activated carbon was activated at 650 °C for 1.25 hours under nitrogen protection, cooled, impregnated with a ferric nitrate solution with a mass fraction of 1.5%, the solid-liquid ratio was 1:4, and after drying, iron oxide was loaded, and the content of Fe3O4 was 4% of the mass of the activated carbon.

[0203] The zeolite molecular sieve was pretreated before use, and the pretreatment method is as follows:

[0204] The zeolite molecular sieve was mixed with an aqueous solution of cetyltrimethylammonium bromide with a mass fraction of 3% at a solid-liquid ratio of 1:6.5, and reacted at 85 °C for 3.5 hours for ion exchange to adjust the pore size to 0.65 nm. The amphiphilic surfactant is a polyethylene glycol-polypropylene glycol block copolymer with a molecular weight of 2500 and an HLB value of 15.

[0205] Comparative Example 1

[0206] Fischer-Tropsch wax was used as the warm mix additive. Other steps were the same as in Example 1.

[0207] Performance test experiment of warm mix odorless asphalt

[0208] I. Experimental scheme

[0209] 1. Sample preparation

[0210] Warm mix odorless asphalt samples were prepared according to the methods of Examples 1-5 and Comparative Example 1. The specific differences are as follows:

[0211] Comparative Example 1: Fischer-Tropsch wax (single warm mix additive) was used, and the remaining steps were the same as in Example 1. The composite warm mix additive was replaced with an equal mass of Fischer-Tropsch wax.

[0212] Example 1: Basic formulation, containing a composite warm mix additive (fatty acid amide, polyoxyethylene ether surfactant, zinc octoate, epoxy soybean oil) and a diatomite odor remover.

[0213] Example 2: Add the control of physical and chemical parameters of the composite warm mix agent, modifiers (SBS + maleic anhydride grafted polyethylene + nano-montmorillonite), and two-stage heating process.

[0214] Example 3: Further pre-treat the mineral fillers (limestone powder, modified bentonite).

[0215] Example 4: Further add nano-graphene oxide to the composite warm mix agent.

[0216] Example 5: Compound odorless agents (diatomite + activated carbon + zeolite molecular sieve + amphiphilic surfactant) and optimize the pre-treatment process.

[0217] 2. Key control parameters

[0218]

[0219]

[0220] II. Test methods

[0221] 1. Conventional performance tests of asphalt

[0222] Penetration (25°C, 0.1 mm)

[0223] Evaluate the hardness of asphalt according to GB / T 4509-2010 "Determination of Penetration of Bitumen", measure the depth of the test needle vertically penetrating into the asphalt sample, and reflect the hardness of the asphalt.

[0224] Softening point (°C)

[0225] Determine according to GB / T 4507-2014 "Determination of Softening Point of Bitumen (Ring-and-Ball Method)", and characterize the high-temperature stability of asphalt by the temperature when the steel ball sinks to a specified distance.

[0226] Ductility (25°C, cm)

[0227] Test according to GB / T 4508-2010 "Determination of Ductility of Bitumen", and measure the low-temperature crack resistance by the length when the asphalt sample is stretched to break with a standard mold.

[0228] Dynamic viscosity (60°C, Pa·s)

[0229] Evaluate the construction fluidity according to JT / T 270-2020 "Determination of Viscosity of Bitumen" (domestic) or ASTM D4402-23 "Determination of Dynamic Viscosity of Bitumen (Rotational Viscometer Method)", and measure the flow resistance of asphalt at 60°C using a rotational viscometer.

[0230] Elastic recovery rate (25°C, %)

[0231] Determined according to ASTM D6084-18 "Test Method for Elastic Recovery of Modified Asphalt", applicable to modified asphalt, and the elastic recovery ratio is calculated through a tension-retraction test.

[0232] 2. Warm Mix Effect Test

[0233] Discharge Temperature (°C)

[0234] The actual discharge temperature after cooling of the third mixture is measured using a calibrated thermocouple (compliant with GB / T 19022-2016 "Requirements for Measurement Management System").

[0235] Construction Temperature (°C)

[0236] According to the requirements of JTG / T 3650-2020 "Technical Specification for Construction of Warm Mix Asphalt Pavement", the suitable paving temperature of asphalt mixture is ≤130 °C, and it is monitored on-site using an infrared thermometer.

[0237] 3. Odorless Performance Test

[0238] VOC Emission (60 min, mg / m 3 )

[0239] Determined according to JT / T 1375-2020 "Test Method for Emission of Volatile Organic Compounds (VOCs) from Asphalt Mixtures":

[0240] Heat the asphalt sample to the construction temperature (140-150 °C) and place it in a closed environmental chamber;

[0241] Collect and analyze the total amount of volatile organic compounds within 60 minutes through a headspace-gas chromatography-mass spectrometry (GC-MS) instrument, with the unit of mg / m 3 .

[0242] Benzo[a]pyrene Adsorption Rate (%)

[0243] Determined according to HJ 647-2013 "Determination of Polycyclic Aromatic Hydrocarbons in Ambient Air and Exhaust Gas - High Performance Liquid Chromatography Method":

[0244] Heat the asphalt at 140-150 °C and capture the released gas through a flue gas collection device;

[0245] Use a quartz fiber filter membrane to intercept benzo[a]pyrene particles, and after solvent extraction, analyze the concentration with a high performance liquid chromatography (HPLC) instrument to calculate the removal rate.

[0246] Hydrogen Sulfide Removal Rate (%)

[0247] Determined according to HJ 533-2009 "Determination of Hydrogen Sulfide in Ambient Air and Exhaust Gas - Methylene Blue Spectrophotometry" (domestic) or ASTM D5504-12 "Determination of Hydrogen Sulfide, Mercaptans, and Other Sulfides" (international):

[0248] Heat the asphalt to 140 - 150 °C in a closed system and collect the released gas;

[0249] Use the methylene blue colorimetric method (HJ 533 - 2009) or gas chromatography (ASTM D5504 - 12) to measure the hydrogen sulfide concentration, and calculate the removal rate by the difference in concentration before and after treatment.

[0250] III. Experimental Data

[0251]

[0252] IV. Data Analysis (Analyze separately for examples and comparative examples) 1. Comparative Example 1 (Single Fischer - Tropsch wax warm mix additive)

[0253] Formulation and process: Only use Fischer - Tropsch wax as the warm mix additive, without pretreatment of modifiers and odor - reducing agents, and the matrix asphalt heating and mixing process is simple.

[0254] Performance:

[0255] Conventional performance: Softening point 52 °C (the lowest), penetration 75 (0.1 mm), ductility 80 cm, elastic recovery rate 70%. Due to the single warm mix additive only providing physical lubrication without chemical cross - linking or molecular enhancement, it is prone to softening at high temperatures and cracking at low temperatures.

[0256] Warm mix effect: Discharge temperature 95 °C, construction temperature 140 °C (the highest), dynamic viscosity 1200 Pa·s (the largest), requiring high - temperature construction and high energy consumption.

[0257] Odor - reducing performance: VOC emission 200 mg / m 3 (the highest), benzo[a]pyrene adsorption rate 60%, hydrogen sulfide removal rate 50%, relying only on the single physical adsorption of diatomite, with weak ability to capture complex odors.

[0258] Defect summary: The single component results in limited warm mix effect, insufficient modification, and weak odor - reducing ability, unable to meet the high - performance and environmental protection requirements.

[0259] 2. Example 1 (Basic composite warm mix additive + diatomite)

[0260] Key improvement: Introduce a four - component composite warm mix additive (fatty acid amide + polyoxyethylene ether + zinc octoate + epoxy soybean oil), and the odor - reducing agent is single diatomite.

[0261] Performance analysis:

[0262] Conventional properties: softening point 58°C (11.5% higher than Comparative Example 1), penetration 70 (0.1 mm) (6.7% lower), ductility 95 cm (18.8% higher), elastic recovery rate 80% (14.3% higher). The composite warm mix agent reduces the interfacial tension through surfactants and catalyzes cross-linking with zinc octoate, initially improving high-temperature stability and low-temperature elasticity.

[0263] Warm mix effect: discharge temperature 80°C (15.8% lower), construction temperature 125°C, dynamic viscosity 900 Pa·s (25% lower), achieving preliminary warm mixing, and the construction temperature is 15°C lower than that of Comparative Example 1.

[0264] Odorless performance: VOC emission 150 mg / m 3 (25% lower), benzo[a]pyrene adsorption rate 75%, hydrogen sulfide removal rate 65%. The porous structure of diatomite adsorbs medium and large molecular odors, and the odorless effect is initially manifested.

[0265] Conclusion: The composite warm mix agent lays the foundation for warm mixing, and diatomite initiates the odorless function, but there is still room for improvement in modification and odorlessness.

[0266] 3. Example 2 (Modifier compounding: SBS + maleic anhydride grafted polyethylene + nano-montmorillonite)

[0267] Key improvement: Based on Example 1, modifiers are added, and the mass ratio of the three is 1:0.5:0.3.

[0268] Performance analysis:

[0269] Conventional properties: softening point 60°C (3.4% higher than Example 1), penetration 68 (0.1 mm) (2.9% lower), elastic recovery rate 85% (6.2% higher). SBS forms an elastic network, and the layered structure of nano-montmorillonite hinders the movement of molecular chains, significantly improving high-temperature stability and elasticity.

[0270] Warm mix effect: discharge temperature 78°C (2.5% lower than Example 1), construction temperature 120°C, dynamic viscosity 850 Pa·s (5.6% lower), and the warm mix effect is gradually optimized.

[0271] Odorless performance: VOC emission 120 mg / m 3 (20% lower), benzo[a]pyrene adsorption rate 80%. The modifiers do not directly affect odorlessness, but the asphalt colloid structure becomes denser, reducing odor volatilization.

[0272] Conclusion: Modifier compounding is the key to improving high-temperature stability and elasticity. The warm mix effect is continuously optimized, and the odorless performance depends on the improvement of the compatibility between the filler and the asphalt.

[0273] 4. Example 3 (Mineral filler pretreatment: stearic acid modified limestone powder + silane coupling bentonite)

[0274] Key improvement: Surface modification pretreatment of limestone powder and bentonite.

[0275] Performance analysis:

[0276] Conventional performance: Ductility 105 cm (5.0% higher than Example 2), elastic recovery rate 88% (3.5% higher), penetration 67 (0.1 mm) (1.5% lower). Stearic acid modification improves the hydrophobicity of limestone powder, and silane coupling expands the interlayer spacing of bentonite to 2.8 nm, enhancing the interfacial adhesion force and significantly improving the low-temperature toughness.

[0277] Warm mixing effect: Discharge temperature 76 °C (2.6% lower), construction temperature 115 °C, dynamic viscosity 800 Pa·s (5.9% lower). Pretreatment of fillers indirectly reduces the viscosity of asphalt, further enhancing the warm mixing effect.

[0278] Odorless performance: VOC emission 100 mg / m 3 (16.7% lower). Surface modification of fillers reduces water adsorption and indirectly inhibits the release of odor components.

[0279] Conclusion: Pretreatment of fillers is the key to breakthrough in low-temperature performance. At the same time, the odorless effect is improved by enhancing the colloidal density, and the warm mixing effect is linearly optimized.

[0280] 5. Example 4 (Addition of nano-graphene oxide: 0.2% of the total mass of the composite warm mix additive)

[0281] Key improvement: Addition of nano-graphene oxide to the composite warm mix additive, modified by amino-silane coupling agent.

[0282] Performance analysis:

[0283] Conventional performance: Softening point 64 °C (4.9% higher than Example 3), penetration 63 (0.1 mm) (5.9% lower), ductility 110 cm (4.8% higher). Nano-graphene oxide forms a "nano-reinforcement network", and the two-dimensional sheets adsorb asphalt molecules, significantly restricting the movement of molecular chains, and achieving a leapfrog improvement in high-temperature stability and low-temperature toughness.

[0284] Warm mixing effect: Discharge temperature 74 °C (2.6% lower), construction temperature 110 °C, dynamic viscosity 750 Pa·s (6.3% lower). Nano-materials improve the thermal conductivity of asphalt, reduce the activation energy, and significantly enhance the warm mixing effect due to the intervention of nano-materials.

[0285] Odorless performance: VOC emission 80 mg / m 3 (20% lower), benzo[a]pyrene adsorption rate 88%. The nano-sheets hinder the diffusion of odor molecules, and the odorless performance is further improved with the optimization of the microstructure.

[0286] Conclusion: Nano-graphene oxide is the core of warm mix and conventional performance breakthrough. Its two-dimensional structure endows asphalt with multiple advantages of "reinforcement - viscosity reduction - diffusion resistance".

[0287] 6. Example 5 (compound odor remover + process optimization: diatomite + activated carbon + zeolite molecular sieve + amphiphilic surfactant)

[0288] Key improvement: Four-component compounding of odor remover (mass ratio 5:3:1:0.5), and optimization of pretreatment process.

[0289] Performance analysis:

[0290] Conventional performance: Softening point 66 °C (3.1% ↑ compared with Example 4), ductility 115 cm (4.5% ↑), elastic recovery rate 92% (2.2% ↑). The synergistic effect of multi-scale reinforcing materials (SBS + nano-montmorillonite + graphene) reaches the performance peak.

[0291] Warm mix effect: Discharge temperature 72 °C (2.7% ↓), construction temperature 105 °C, dynamic viscosity 700 Pa·s (6.7% ↓), achieving the best state of "low temperature and high fluidity", and the discharge temperature is 24.2% lower than that of Comparative Example 1.

[0292] Odor removal performance: VOC release amount 60 mg / m 3 (25% ↓ vs Example 4), benzo[a]pyrene adsorption rate 92%, hydrogen sulfide removal rate 85%. Diatomite captures macromolecules, activated carbon chemically adsorbs polar molecules, zeolite molecular sieve sieves small molecules, and amphiphilic surfactant enhances compatibility, forming a synergistic effect of "pore size graded adsorption", and the odor removal rate reaches the highest.

[0293] Conclusion: The compound odor remover is the key to environmental protection performance breakthrough. Combined with the optimization of the whole system, Example 5 reaches the best in terms of warm mix, modification and odor removal, meeting the dual requirements of heavy traffic roads and green construction.

[0294] V. Comprehensive conclusion

[0295] Comparative Example 1 verifies the limitations of single component in warm mix, modification and odor removal, highlighting the necessity of composite system.

[0296] Examples 1 - 4 are gradually improved through "compound warm mix agent → modifier → filler pretreatment → nano-material", gradually improving the high temperature stability (softening point 26.9% ↑), low temperature toughness (ductility 43.75% ↑), and warm mix effect (construction temperature 35 °C ↓).

[0297] Example 5, relying on the compound odor remover and process optimization, realizes a 70% ↓ in VOC release amount and a 70% ↑ in characteristic pollutant removal rate, becoming the only group that meets the strict environmental protection standards.

[0298] Core mechanism: The synergy of multiple components (such as SBS elastic network + nano-montmorillonite layered barrier + graphene reinforcement) and process control (two-stage heating + gradient cooling) are the keys to the performance leap, proving that the systematic innovation of "component design + process optimization" is significantly superior to single improvement.

[0299] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A preparation method of warm mix and odorless asphalt, characterized in that It includes the following steps: After heating the base asphalt to 140 - 150 °C, a composite warm mix additive and an odorless agent are added to the base asphalt, and then a spiral stirrer is used to stir at a speed of 180 - 220 revolutions per minute for 20 - 30 minutes to form a first mixture; wherein, the composite warm mix additive includes fatty acid amide, polyoxyethylene ether surfactant, zinc octoate, and epoxidized soybean oil, and the mass ratio of the four is 2.8 - 3.2:0.9 - 1.1:0.4 - 0.6:0.2 - 0.4; the addition amount of the composite warm mix additive is 0.7 - 1.3% of the mass of the base asphalt; the odorless agent includes diatomite, and the addition amount of the odorless agent is 0.5 - 0.9% of the mass of the base asphalt; After cooling the first mixture to 118 - 132 °C, a modifier is added, and then the spiral stirrer speed is maintained at 180 - 220 revolutions per minute and stirring continues for 30 - 40 minutes to form a second mixture; wherein, the modifier contains styrene - butadiene block copolymer, and the addition amount of the modifier is 3.5 - 6.5% of the mass of the base asphalt; Mineral filler is added to the second mixture, and then stirring is maintained at a temperature of 118 - 132 °C for 12 - 18 minutes to form a third mixture; wherein, the mineral filler is composed of limestone powder and modified bentonite, and the mass ratio of the two is 6.5 - 7.5:0.8 - 1.2, and the addition amount of the mineral filler is 4.5 - 7.5% of the total mass of the base asphalt, composite warm mix additive, odorless agent, and modifier; The third mixture is cooled to 72 - 85 °C and then discharged.

2. The preparation method of the warm mix and odorless asphalt according to claim 1, wherein, The composite warm mix additive meets the following physical and chemical parameters: the carbon chain length of the fatty acid amide is C16 - C18, and the saponification value is 170 - 210 mgKOH / g; the polyoxyethylene ether surfactant is fatty alcohol polyoxyethylene ether, the HLB value is 11.5 - 14.5, and the ethylene oxide addition number is 7 - 11; the zinc content of zinc octoate is 10 - 16% calculated by the mass percentage of zinc element in zinc octoate; the hydroxyl value of epoxidized soybean oil is 38 - 52 mgKOH / g; The silica content of the diatomaceous earth is ≥ 85%, calculated as the mass percentage of silica in the diatomaceous earth, and the specific surface area is 30 - 50 m 2 / g; The mass ratio of the composite warm mix additive to the odorless agent is 1.4:1 - 2.6:1; The styrene content of the styrene - butadiene block copolymer is 28 - 37%; The calcium carbonate content of the limestone powder is ≥90%, and the particle size is ≤0.075 mm.

3. The preparation method of the warm mix and odorless asphalt according to claim 2, characterized in that The modifier also includes maleic anhydride grafted polyethylene and nano - montmorillonite, and the mass ratio of the three is styrene - butadiene block copolymer: maleic anhydride grafted polyethylene: nano - montmorillonite = 1:0.5:0.3, and the total addition amount of the modifier is 3.5 - 6.5% of the mass of the base asphalt.

4. The preparation method of the warm mix and odorless asphalt according to claim 1, characterized in that, The heating process of the base asphalt is carried out in two stages: In the first stage, the base asphalt is heated from room temperature at a heating rate of 4 - 6 °C per minute to 125 - 135 °C and kept at this temperature for 10 - 15 minutes; In the second stage, it continues to be heated at a heating rate of 2 - 3 °C per minute to 140 - 150 °C, and after reaching the target temperature, the composite warm mix additive and the odorless agent are added.

5. The preparation method of the warm mix and odorless asphalt according to claim 1, characterized in that, Before the third mixture is cooled, it needs to be filtered. The filtration process specifically includes the following steps: A double-layer gradient filter screen is used. The upper layer is a corrugated stainless steel filter screen with a pore size of 2.5 - 3.0 mm, and the lower layer is a plain woven galvanized filter screen with a pore size of 2.0 - 2.5 mm; the filtration pressure is controlled at 0.15 - 0.25 MPa, and a nano-silica anti-sticking layer with a mass fraction of 0.5 - 1.0% is pre-coated on the surface of the filter screen; the temperature of the discharged material after filtration is controlled at 108 - 117 °C; The cooling method is specifically as follows: The filtered asphalt is cooled in two stages. In the first stage, it is cooled from 108 - 117 °C to 95 - 100 °C at a rate of 3.0 - 3.5 °C per minute for 5 - 8 minutes; in the second stage, it is cooled from 95 - 100 °C to 72 - 85 °C at a rate of 2.0 - 2.5 °C per minute for 12 - 15 minutes.

6. The preparation method of the warm mix and odorless asphalt according to claim 1, characterized in that, Before the limestone powder is used, it is pretreated through the following steps: The limestone powder is impregnated in a stearic acid ethanol solution with a mass fraction of 3 - 5% according to a solid-liquid mass ratio of 1:3 - 1:5, and ultrasonic treatment is carried out at 80 - 90 °C for 20 - 30 minutes. The ultrasonic power density is 0.5 - 0.8 W / mL, and the frequency is 40 - 60 kHz; after treatment, centrifugal separation is carried out. The centrifugal rotation speed is 3000 - 4000 rpm, and the time is 10 - 15 minutes. The solid product is vacuum dried at 60 - 70 °C for 2 - 3 hours; The modified bentonite is prepared through the following steps: Bentonite and deionized water are mixed according to a mass ratio of 1:10 - 1:15, and cetyltrimethylammonium bromide is added. Its addition amount is 15 - 20% of the dry basis mass of bentonite. Stirring reaction is carried out at 50 - 60 °C for 4 - 6 hours to enable cetyltrimethylammonium bromide to enter the interlayer of bentonite through ion exchange to form an organic modified layer. After the reaction, suction filtration is carried out and washed with water until there are no free bromide ions in the filtrate. The solid is dried at 80 - 90 °C to constant weight to obtain organic bentonite; The organic bentonite prepared above is mixed with a γ-aminopropyltriethoxysilane ethanol solution with a mass fraction of 2 - 4% according to a solid-liquid mass ratio of 1:5 - 1:8, and ultrasonic treatment is carried out at 60 - 70 °C for 30 - 40 minutes. After treatment, centrifugal separation is carried out, and the solid is vacuum dried at 60 - 70 °C for 2 - 3 hours to obtain modified bentonite.

7. The preparation method of the warm mix and odorless asphalt according to claim 1, characterized in that, The composite warm mix additive also includes nano-graphene oxide, and the addition amount of nano-graphene oxide is 0.1 - 0.3% of the total mass of the composite warm mix additive; the total addition amount of the composite warm mix additive is 0.7 - 1.3% of the mass of the matrix asphalt; The preparation method of the nano-graphene oxide is as follows: Natural graphite powder is added to a mixed acid of concentrated sulfuric acid and concentrated phosphoric acid. Among them, the volume ratio of concentrated sulfuric acid to concentrated phosphoric acid is 9:

1. Stirring is carried out for 30 minutes under ice bath conditions, and then potassium permanganate is slowly added. The mass ratio of potassium permanganate to graphite powder is 6:

1. The reaction temperature is controlled not to exceed 20 °C, and stirring reaction is carried out for 2 hours; the reaction system is heated to 50 °C, and stirring reaction is continued for 12 hours. Then the reaction solution is slowly poured into ice water, and at the same time, a hydrogen peroxide solution with a mass fraction of 30% is added until the color of the solution becomes bright yellow. After stirring evenly, it is left to stand and precipitate; The precipitate was repeatedly washed with deionized water until neutral, then centrifuged, and the obtained solid was vacuum-dried at 60 °C for 24 hours to obtain graphene oxide; The graphene oxide was dispersed in absolute ethanol to form a graphene oxide dispersion with a mass fraction of 0.5-1%. γ-Aminopropyltriethoxysilane, an amino-silane coupling agent, was added thereto, and its addition amount was 1-2% of the mass of graphene oxide. The mixture was refluxed and stirred at 80 °C for 6 hours to cause a condensation reaction between the amino-silane coupling agent and the hydroxyl groups on the surface of graphene oxide, forming a grafted modification layer; after the reaction, the product was centrifuged, washed repeatedly with absolute ethanol, and then vacuum-dried at 60 °C for 12 hours to obtain nano-graphene oxide with an amino-silane coupling agent grafted on its surface; The dispersion treatment step of the nano-graphene oxide is as follows: Take 1 / 3-1 / 2 of the total mass of epoxidized soybean oil in the composite warm mix additive and add nano-graphene oxide to a reaction vessel, and perform ultrasonic treatment at 50-60 °C. The ultrasonic frequency is 40-60 kHz, the power density is 0.3-0.5 W / mL, and the treatment time is 10-15 minutes to uniformly disperse the nano-graphene oxide in this part of epoxidized soybean oil; Subsequently, continue ultrasonic treatment for 5-8 minutes to cause a condensation reaction between the amino-silane coupling agent and the hydroxyl groups on the surface of nano-graphene oxide, forming a grafted modification layer to obtain a pre-dispersed nano-graphene oxide mixture; Mix the remaining epoxidized soybean oil with fatty acid amide, polyoxyethylene ether surfactant, and zinc octoate, and synchronously add them to the matrix asphalt with the above-mentioned pre-dispersed nano-graphene oxide mixture. Control the rotation speed of the spiral stirrer to be 200-220 revolutions per minute, the shear rate ≥ 600 s-1, and continuously stir for 8-10 minutes to uniformly disperse the nano-graphene oxide in the asphalt system through the action of mechanical shear force.

8. The preparation method of the warm mix and odorless asphalt according to claim 1, characterized in that, The odor remover also includes activated carbon, zeolite molecular sieve, and amphiphilic surfactant. The mass ratio of diatomite, activated carbon, zeolite molecular sieve, and amphiphilic surfactant is 5:3:1:0.5; the total addition amount of the odor remover is 0.5-0.9% of the mass of the matrix asphalt; The diatomite was pretreated before use, and its pretreatment method is as follows: The diatomite was impregnated in a hydrochloric acid solution with a mass fraction of 5-8%, and the solid-liquid ratio was 1:4-1:

6. It was stirred at 60-70 °C for 1-2 hours to remove impurities, and then washed with water until neutral and dried; The activated carbon was pretreated before use, and its pretreatment method is as follows: The activated carbon was activated at 600-700 °C for 1-1.5 hours under nitrogen protection, cooled, impregnated with a ferric nitrate solution with a mass fraction of 1-2%, and the solid-liquid ratio was 1:3-1:

5. After drying, iron oxide was loaded, and the content of Fe3O4 was 3-5% of the mass of the activated carbon; The zeolite molecular sieve was pretreated before use, and its pretreatment method is as follows: The zeolite molecular sieve was mixed with an aqueous solution of cetyltrimethylammonium bromide with a mass fraction of 2-4% according to a solid-liquid ratio of 1:5-1:8, and reacted at 80-90 °C for 3-4 hours for ion exchange to adjust the pore size to 0.5-0.8 nm; The amphiphilic surfactant is a polyethylene glycol - polypropylene glycol block copolymer with a molecular weight of 2000 - 3000 and an HLB value of 14 - 16.

9. The preparation method of the warm mix and odorless asphalt according to claim 3, characterized in that, The maleic anhydride grafted polyethylene is prepared by the following melt grafting method: Mix low - density polyethylene particles, maleic anhydride, diisopropylbenzene peroxide and nano - zinc oxide in a mass ratio of 100:1.5 - 2.5:0.3 - 0.6:0.5 - 1.

0. Among them, the nano - zinc oxide is pre - treated with a 5% stearic acid ethanol solution under the condition of a solid - liquid ratio of 1:10 and ultrasonically dispersed at 60 °C for 30 minutes; add the mixed materials into a twin - screw extruder, and control the temperature of each section of the extruder as follows: the feeding section is 160 - 170 °C, the melting section is 180 - 190 °C, the reaction section is 200 - 210 °C, the extrusion section is 190 - 200 °C, the screw speed is 200 - 250 rpm, and the reaction time is 3 - 5 minutes; after the extrudate is cooled and pelletized by water, it is dried in a vacuum drying oven at 50 °C for 8 - 10 hours to obtain maleic anhydride grafted polyethylene; The nano - montmorillonite is prepared by the following steps: Mix the original nano - montmorillonite soil and deionized water in a mass ratio of 1:8 - 1:12, disperse at a stirring rate of 300 - 500 rpm for 20 - 30 minutes, add γ - aminopropyltriethoxysilane with a mass fraction of 1 - 3%, and stir and react at 50 - 60 °C for 2 - 3 hours to graft the silane coupling agent onto the surface of montmorillonite through chemical bonding; after the reaction, filter by suction, wash with deionized water until the filtrate is clear, and dry the solid at 80 - 90 °C to constant weight to obtain nano - montmorillonite.

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