Mixture of bio-based resin asphalt cooperating with waste asphalt and steel slag as well as preparation method and application of mixture

Abstract

The invention belongs to the technical field of road engineering materials, and relates to a mixture of bio-based resin asphalt, waste asphalt and steel slag as well as a preparation method and application of the mixture. The mixture comprises the following raw materials in parts by mass: 40-70 parts of steel slag aggregate, 40-70 parts of old asphalt, 4-8 parts of bio-based polyurethane resin, 2-4 parts of a composite regenerant and 10-20 parts of matrix asphalt, and the steel slag aggregate comprises one or more of converter steel slag, electric furnace steel slag and open-hearth steel slag; the bio-based polyurethane resin takes vegetable oil as a raw material, and the vegetable oil comprises one or more of tung oil, linseed oil, castor oil, soybean oil and palm oil. The method aims at solving the problems that a traditional asphalt source depends on non-renewable resources, and a large amount of old asphalt materials and steel slag are difficult to treat, meanwhile, the defects of a method for preparing the high-performance road mixture through cooperation of asphalt and steel slag in the prior art are overcome, effective recycling of resources is achieved, and the requirements of road engineering application are met.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering materials, and specifically to a mixture of bio-based resin asphalt, waste asphalt and steel slag, and a preparation method and application thereof, wherein a high-performance sustainable road mixture is prepared by combining bio-based resin asphalt with waste asphalt and steel slag. The present invention aims to provide a mixture material with both high performance and sustainability for road engineering through innovative material combination and preparation process. Background Art

[0002] In the process of road construction and maintenance, asphalt is widely used as the main pavement material. However, most traditional asphalt comes from non-renewable petroleum resources. With the continuous expansion of road construction and the increase in the service life of roads, the demand for asphalt continues to rise, which makes the consumption pressure of non-renewable resources increasingly greater. At the same time, a large amount of waste asphalt will be generated during the renovation and reconstruction of roads. If this waste asphalt is not effectively recycled, it will not only cause a serious waste of resources, but also may cause pollution to environmental elements such as soil and water due to random discarding or improper treatment.

[0003] The steel slag produced during the steel production process also faces the problem of treatment. As the main by-product of the steel industry, steel slag has a huge output. The stacking of a large amount of steel slag not only occupies a large amount of land resources, but also some harmful substances contained in the steel slag may seep out with the action of rainwater erosion, thereby polluting the surrounding soil and water. Therefore, the effective recycling of steel slag can not only solve the environmental problems it brings, but also turn waste into treasure, making it a usable resource in fields such as road engineering.

[0004] Currently, there is a lack of means to effectively process waste asphalt and steel slag generated during steel production; there is also a lack of high-performance sustainable road mixtures that can be used for paving roads. Summary of the invention

[0005] Based on the above-mentioned defects in the prior art, the purpose of the present invention is to provide a method for preparing a high-performance sustainable road mixture by using bio-based resin asphalt in conjunction with waste asphalt and steel slag to solve the above-mentioned problems.

[0006] As a new type of material, bio-based resin has many significant advantages in the field of road engineering materials. First of all, its raw materials mainly come from renewable biomass resources, such as vegetable oils (tung oil, linseed oil, castor oil, soybean oil, palm oil, etc.), which makes the production of bio-based resin independent of non-renewable petroleum resources and conforms to the concept of sustainable development. Secondly, bio-based resins usually have good biodegradability and can gradually decompose in the natural environment after their service life, reducing the risk of long-term pollution to the environment. In addition, bio-based resins also have certain chemical stability and physical properties, which can improve the adhesion, flexibility and other properties of road mixtures, and help improve the overall quality of road mixtures.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present application provides a mixture of bio-based resin asphalt, waste asphalt and steel slag, and the raw materials include, by weight:

[0009] 40-70 parts of steel slag aggregate, 40-70 parts of old asphalt materials, 4-8 parts of bio-based polyurethane resin, 10-20 parts of base asphalt, and 2-4 parts of composite regeneration agent.

[0010] Furthermore, the steel slag aggregate includes one or more of converter steel slag, electric furnace steel slag, and open-hearth steel slag.

[0011] Preferably, the steel slag aggregate is a mixture of converter steel slag and electric furnace steel slag; the mass ratio of converter steel slag to electric furnace steel slag in the mixture is 1:1 to 3.5.

[0012] Furthermore, the free calcium oxide content of the steel slag aggregate is not higher than 1.7%, and the polishing value is not lower than 45.

[0013] Steel slag is the main by-product of the steelmaking process, with a huge output. Applying it to the preparation of road mixtures realizes the effective reuse of this industrial waste, which not only reduces the occupation and potential pollution of steel slag to the environment, but also reduces the dependence of road projects on natural aggregates, which is in line with the concept of sustainable development.

[0014] Furthermore, the old asphalt material comes from waste asphalt mixture generated during road construction and maintenance.

[0015] Furthermore, the bio-based polyurethane resin is obtained by reacting vegetable oil with polyol and isocyanate. The specific operation steps are as follows: the bio-based polyurethane resin is obtained by reacting vegetable oil with polyol at a temperature of 150°C to 180°C to obtain a first intermediate product. The first intermediate product is directly subjected to an addition polymerization reaction with isocyanate at 40°C to 60°C to obtain a bio-based polyurethane resin.

[0016] Furthermore, the vegetable oil includes at least one of tung oil, linseed oil, castor oil, soybean oil, and palm oil; the polyol includes one or more of trimethylolethane, dipentaerythritol, polycarbonate polyol, and butanediol; the isocyanate includes one or more of p-phenylene diisocyanate (PPDI), adamantane diisocyanate (ADDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI).

[0017] Furthermore, the first intermediate product is a mixture of various components including a modified vegetable oil ester structure and incompletely reacted polyols, and its molecular structure has more active sites (mainly hydroxyl groups) that can be further reacted compared to the original vegetable oil, so as to facilitate subsequent addition polymerization reaction with isocyanate.

[0018] Furthermore, the mixing molar ratio of the vegetable oil to the polyol is 1:1-3; and the mixing molar ratio of the first intermediate product to the isocyanate is 1:0.8-1.5.

[0019] Furthermore, the base asphalt is 70A base asphalt.

[0020] Furthermore, the composite regeneration agent is prepared by mixing plant extracts, microbial fermentation products, functional additives and aromatic oil in proportion.

[0021] Furthermore, the plant extract is ginkgo leaf extract, the microbial fermentation product is a Bacillus fermentation product, which is a product obtained by fermenting Bacillus through a liquid fermentation method; and the functional additives are butylated hydroxyanisole, dibutylhydroxytoluene and N,N'-di-sec-butyl-p-phenylenediamine.

[0022] Preferably, the mixing mass ratio of the plant extract, microbial fermentation product, functional additive and aromatic oil is (2-3):(1-2):(4-5):(1-2).

[0023] The second technical solution of the present application provides a method for preparing a mixture of bio-based resin asphalt, waste asphalt and steel slag, the preparation method comprising the following steps:

[0024] S1. Prepare the raw materials according to the ratio described in the technical solution 1, pre-treat the steel slag aggregate and asphalt waste material; prepare the bio-based polyurethane resin; prepare the composite regeneration agent; and set aside;

[0025] S2. The composite regeneration agent is fully mixed with the pretreated asphalt waste material to obtain the regenerated asphalt waste material for standby use;

[0026] S3. The bio-based polyurethane resin is mixed with the base asphalt to obtain a bio-based polyurethane resin asphalt;

[0027] S4. Add the recycled asphalt obtained in S2, the bio-based polyurethane resin asphalt and steel slag obtained in S3 into a mixing device, and stir them evenly to obtain a mixture of bio-based resin asphalt, waste asphalt and steel slag.

[0028] Furthermore, the pretreatment process of the steel slag aggregate in step S1 is: by screening, removing oversized particles and impurities therein, to obtain qualified steel slag, the specific particle size of which ranges from 0 mm to 10 mm, and is not 0.

[0029] Furthermore, the pretreatment of the asphalt waste material in step S1 includes the following steps: collecting the asphalt waste material, removing impurities such as stones and soil therein through mechanical treatment means such as crushing and screening, and obtaining relatively pure asphalt waste material particles with a particle size range of 0mm to 15mm, and not 0.

[0030] Furthermore, the preparation of the bio-based polyurethane resin in step S1 includes the following steps: using vegetable oil as a starting material, subjecting the vegetable oil to an ester exchange reaction with a polyol at a temperature of 150°C to 180°C to obtain a first intermediate product; and subjecting the first intermediate product to an addition polymerization reaction with an isocyanate at a temperature of 40°C to 60°C to obtain a bio-based polyurethane resin.

[0031] Furthermore, before the preparation of the bio-based polyurethane resin asphalt in step S3, the base asphalt needs to be preheated to 120° C. to 130° C. The purpose of preheating is mainly to: improve fluidity, reduce the viscosity of the base asphalt, facilitate uniform dispersion during mixing, ensure full combination with the polyurethane resin; reduce bubbles, save energy consumption, improve operational safety, and prevent operational difficulties caused by cold asphalt.

[0032] Furthermore, the stirring speed in step S4 is in the range of 200 to 600 rpm, the specific temperature is 40 to 60° C., and the specific time is 1 to 3 hours.

[0033] The third technical solution of the present invention provides an application of a mixture of bio-based resin asphalt, waste asphalt and steel slag as described in the above technical solution, wherein the application refers to the application of the mixture in the field of road engineering material technology, and the mixture is used for paving sustainable roads. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0035] The raw materials used in the present invention are all purchased from the market, and there is no particular restriction on their sources. They can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0036] Embodiment 1:

[0037] Bio-based resin asphalt, waste asphalt and steel slag are used to prepare high-performance sustainable road mixtures:

[0038] S1. A mixture of converter slag and electric furnace slag in a mass ratio of 1:1.5 is selected as slag aggregate. The free calcium oxide content of the selected slag is 1.6% and the polishing value is 48. After screening, the oversized particles and impurities are removed to obtain qualified slag aggregate with a particle size ranging from 0mm to 10mm (not 0).

[0039] S2. Through mechanical processing methods such as crushing and screening, impurities such as stones and soil in the old asphalt are removed to obtain relatively pure old asphalt particles with a particle size range of 0mm to 15mm (not 0).

[0040] S3. Prepare bio-based polyurethane resin using tung oil as the starting material. Tung oil is mixed with polycarbonate polyol and dipentaerythritol in a molar ratio of 1:0.9:0.6, and an ester exchange reaction is carried out at 150°C and normal pressure for 2 hours to obtain a first intermediate product. The first intermediate product is a plant oil ester structure that contains the modified (ester exchange reaction). Its molecular structure is more complex than that of the original plant oil and has more active sites (mainly hydroxyl groups) that can be further reacted. Then, the first intermediate product is mixed with p-phenylene diisocyanate and isophorone diisocyanate (IPDI) in a molar ratio of 1:0.8:0.4, and an addition polymerization reaction is carried out at 60°C and normal pressure for 1.5 hours to obtain a bio-based polyurethane resin.

[0041] S4, plant extract, microbial fermentation product, functional additive and aromatic oil are mixed in a mass ratio of 2:2:4:2 to prepare a composite regeneration agent. The plant extract is ginkgo leaf extract, the microbial fermentation product is a bacillus fermentation product, and the functional additive is a mixture of butylated hydroxyanisole, dibutylhydroxytoluene and N, N'-di-sec-butyl-p-phenylenediamine. The bacillus fermentation product described in this embodiment has non-protein amino acids as the main component, and also includes sugars, inorganic salts, protein amino acids and other components. The product is purchased from Guangzhou Northern Lights Biotechnology Co., Ltd., and other commercially available products with similar ingredients and functions can be used as its replacement.

[0042] S5. Fully mix the composite regeneration agent and the treated old asphalt material in a mass ratio of 1:8 to obtain regenerated old asphalt material for standby use.

[0043] S6. Mix the bio-based polyurethane resin and the matrix asphalt in a mass ratio of 1:1.3 to obtain a bio-based polyurethane resin asphalt; add it into a mixing device together with recycled asphalt and steel slag to obtain a mixture; the specific rotation speed range is 200 to 600 rpm, the specific temperature is 60°C, and the specific time is 2 hours.

[0044] Among them, the mass ratio of bio-based polyurethane resin asphalt, recycled asphalt and steel slag is 13.8:41.2:45.

[0045] Embodiment 2:

[0046] Bio-based resin asphalt, waste asphalt and steel slag are used to prepare high-performance sustainable road mixtures:

[0047] S1. A mixture of converter slag and electric furnace slag in a mass ratio of 1:2 is selected as slag aggregate. The free calcium oxide content of the selected slag is 1.6% and the polishing value is 48. After screening, the oversized particles and impurities are removed to obtain qualified slag aggregate with a particle size ranging from 0mm to 10mm (not 0).

[0048] S2. Through mechanical processing methods such as crushing and screening, impurities such as stones and soil in the old asphalt are removed to obtain relatively pure old asphalt particles with a particle size range of 0mm to 15mm (not 0).

[0049] S3, using linseed oil and palm oil mixed in a ratio of 1:0.8 as starting materials to prepare bio-based polyurethane resin. The oil mixture is mixed with trimethylolethane and dipentaerythritol in a molar ratio of 1:0.9:0.7, and an ester exchange reaction is carried out at 150°C and normal pressure for 2 hours to obtain a first intermediate product. Then, the first intermediate product is mixed with adamantane diisocyanate and toluene diisocyanate in a molar ratio of 1:0.7:0.6, and an addition polymerization reaction is carried out at 60°C and normal pressure for 1.5 hours to obtain a bio-based polyurethane resin.

[0050] S4, the plant extract, the microbial fermentation product, the functional additive and the aromatic oil are mixed in a mass ratio of 2:2:4:2 to prepare a composite regeneration agent. The plant extract is ginkgo leaf extract, the microbial fermentation product is a Bacillus fermentation product, and the functional additive is butylated hydroxyanisole, dibutyl hydroxytoluene and N,N'-di-sec-butyl-p-phenylenediamine.

[0051] S5. Fully mix the composite regeneration agent and the treated old asphalt material in a mass ratio of 1:12 to obtain regenerated old asphalt material for standby use.

[0052] S6. Obtain a mixture according to the mixing steps of Example 1.

[0053] Among them, the mass ratio of bio-based polyurethane resin asphalt, recycled asphalt and steel slag is 16.1:43.6:40.3.

[0054] Embodiment 3:

[0055] Bio-based resin asphalt, waste asphalt and steel slag are used to prepare high-performance sustainable road mixtures:

[0056] S1. A mixture of converter slag and electric furnace slag in a mass ratio of 1:2.5 is selected as slag aggregate. The free calcium oxide content of the selected slag is 1.6% and the polishing value is 48. After screening, the oversized particles and impurities are removed to obtain qualified slag aggregate with a particle size ranging from 0mm to 10mm (not 0).

[0057] S2. Through mechanical processing methods such as crushing and screening, impurities such as stones and soil in the old asphalt are removed to obtain relatively pure old asphalt particles with a particle size range of 0mm to 15mm (not 0).

[0058] S3, using tung oil and castor oil mixed in a ratio of 1:0.6 as starting materials to prepare bio-based polyurethane resin. The oil mixture is mixed with trimethylolethane and polycarbonate polyol in a molar ratio of 1:0.6:0.9, and an ester exchange reaction is carried out at 150°C and normal pressure for 2 hours to obtain a first intermediate product. Then, the first intermediate product is mixed with adamantane diisocyanate and hexamethylene diisocyanate in a molar ratio of 1:0.9:0.4, and an addition polymerization reaction is carried out at 60°C and normal pressure for 1.5 hours to obtain a bio-based polyurethane resin.

[0059] S4, preparing a composite regeneration agent by mixing plant extract, microbial fermentation product, functional additive and aromatic oil in a ratio of 2:2:4:2. The plant extract is ginkgo leaf extract, the microbial fermentation product is bacillus fermentation product, and the functional additive is butylated hydroxyanisole, butylated hydroxytoluene and N,N'-di-sec-butyl-p-phenylenediamine.

[0060] S5. Fully mix the composite regeneration agent and the treated old asphalt material in a mass ratio of 1:15 to obtain regenerated old asphalt material for standby use.

[0061] S6. Obtain a mixture according to the mixing steps of Example 1.

[0062] Among them, the mass ratio of bio-based polyurethane resin asphalt, recycled asphalt and steel slag is 15:41:44.

[0063] Comparative Example 1:

[0064] Preparation of traditional asphalt waste material and steel slag mixture:

[0065] Traditional base asphalt is used in conjunction with waste asphalt and steel slag to prepare high-performance sustainable road mixtures:

[0066] S1. A mixture of converter slag and electric furnace slag in a mass ratio of 1:1.5 is selected as slag aggregate. The free calcium oxide content of the selected slag is 1.6% and the polishing value is 48. After screening, the oversized particles and impurities are removed to obtain qualified slag aggregate with a particle size ranging from 0mm to 10mm (not 0).

[0067] S2. Through mechanical processing methods such as crushing and screening, impurities such as stones and soil in the old asphalt are removed to obtain relatively pure old asphalt particles with a particle size range of 0mm to 15mm (not 0).

[0068] S3, the plant extract, microbial fermentation product, functional additive and aromatic oil are mixed in a ratio of 2:2:4:2 to prepare a composite regeneration agent. The plant extract is ginkgo leaf extract, the microbial fermentation product is obtained by fermenting waste crop straw with specific microorganisms, and the functional additive is a mixture of butylated hydroxyanisole, dibutylhydroxytoluene and N,N'-di-sec-butyl-p-phenylenediamine.

[0069] S4. Fully mix the composite regeneration agent with the treated old asphalt material in a mass ratio of 1:8 to obtain regenerated old asphalt material for standby use.

[0070] S5. Add the base asphalt, pretreated old asphalt and steel slag into a mixing device to obtain a mixture; the specific rotation speed range is 200 to 600 rpm, the specific temperature is 60° C., and the specific time is 2 hours.

[0071] Among them, the mass ratio of base asphalt, recycled asphalt and steel slag is 13.8:41.2:45.

[0072] Comparative Example 2:

[0073] Preparation of bio-based resin asphalt with waste asphalt and steel slag road mixture without using composite regeneration agent:

[0074] S1. A mixture of converter slag and electric furnace slag in a mass ratio of 1:2 is selected as slag aggregate. The free calcium oxide content of the selected slag is 1.6% and the polishing value is 48. After screening, the oversized particles and impurities are removed to obtain qualified slag aggregate with a particle size ranging from 0mm to 10mm (not 0).

[0075] S2. Through mechanical processing methods such as crushing and screening, impurities such as stones and soil in the old asphalt are removed to obtain relatively pure old asphalt particles with a particle size range of 0mm to 15mm (not 0).

[0076] S3. Prepare bio-based polyurethane resin by mixing linseed oil and palm oil in a ratio of 1:0.8 as starting materials. Mix the oil mixture with trimethylolethane and dipentaerythritol in a molar ratio of 1:0.9:0.7, and perform an ester exchange reaction at 150°C and normal pressure for 2 hours to obtain a first intermediate product. Then, directly mix the first intermediate product with adamantane diisocyanate and toluene diisocyanate in a molar ratio of 1:0.7:0.6, and perform an addition polymerization reaction at 60°C and normal pressure for 1.5 hours to obtain a bio-based polyurethane resin.

[0077] S4. Obtain a mixture according to the mixing steps of Example 1.

[0078] Among them, the mass ratio of bio-based polyurethane resin asphalt, waste asphalt and steel slag is 16.1:43.6:40.3.

[0079] Test example:

[0080] The asphalt mixtures prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were immediately molded after being discharged and subjected to performance tests. The test results are shown in Table 1.

[0081] Test methods involved in the table:

[0082] (1) Marshall stability

[0083] Marshall stability not only reflects the ability of asphalt mixture to resist shear and compression, but is also related to factors such as the structural compactness of the mixture, the adhesion of asphalt to aggregate, the void ratio of the mixture, etc. Therefore, it is an important parameter for the design and quality control of asphalt pavement structure.

[0084] Test method: The Marshall stability test of asphalt mixture is mainly carried out in accordance with the relevant provisions of the "Testing Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The prepared standard-sized asphalt mixture specimen is placed in a constant temperature water tank at (60±1)℃ for 30 to 40 minutes; the upper and lower pressure heads of the Marshall tester are placed in a water tank or oven to reach the same temperature; the loading device is started to make the specimen bear the load, and the loading rate is (50±5)mm / min; the computer automatically records the sensor pressure and the specimen deformation curve and automatically stores the data in the computer; when the test load reaches the maximum value and begins to decrease, the Marshall tester automatically stops, and the display window shows the Marshall stability value and flow value.

[0085] (2) Water immersion stability

[0086] Water stability is a measure of the ability of an asphalt mixture to maintain its structural stability under the action of water. In highway engineering, asphalt pavements need to be able to resist water penetration and maintain their mechanical properties, especially under wet conditions. Water stability tests are often used to evaluate the water damage resistance of asphalt mixtures. The level of water stability affects the durability and rutting resistance of asphalt pavements in wet conditions. If the water stability of an asphalt mixture is low, it means that it may significantly reduce its load-bearing capacity after contact with water, which may lead to early damage and performance degradation of the pavement. In order to ensure the long-term use of the pavement and reduce maintenance costs, special attention is paid to water stability when designing asphalt mixture formulas, and this performance is optimized by adjusting parameters such as asphalt content, aggregate type and grading. In actual engineering applications, asphalt mixtures with sufficient water stability are selected to meet the requirements of road design specifications.

[0087] The difference between the immersion stability test method and the standard Marshall test method is that the specimen is kept in a constant temperature water bath at (60±1)℃ for 48h, and the rest is the same as the standard Marshall test method.

[0088] (3) Freeze-thaw splitting strength ratio

[0089] The Freeze-Thaw Splitting Tensile Strength Ratio (FTSR) of asphalt is an important indicator for evaluating the freeze-thaw resistance of asphalt mixtures. It refers to the ratio of the splitting strength of the asphalt mixture after multiple freeze-thaw cycles to the splitting strength in the initial non-freeze-thaw state. This ratio can reflect the structural stability and strength loss of asphalt after freezing and melting in a low-temperature environment. Influencing factors: Asphalt type: Different types of asphalt have different adaptability to low-temperature performance, and some modified asphalts can provide better freeze-thaw resistance. Mixture design: Aggregate selection, grading and void ratio will affect the strength after freeze-thaw. Number of freeze-thaw cycles: As the number of freeze-thaw cycles increases, the FTSR of the asphalt mixture may decrease. Processing and construction conditions: Construction temperature and compaction quality will also affect the final performance of the asphalt mixture.

[0090] Test method: The prepared specimens are randomly divided into two groups, with no less than 4 specimens in each group. One group is used as the non-freeze-thaw group (referred to as Group A), and the other group is used as the freeze-thaw group (referred to as Group B); the specimens of Group B are placed in a vacuum dryer, connected to a vacuum pump, and the vacuum pump is started to vacuum saturate the specimens with water; the saturated specimens of Group B are placed in a constant temperature water bath with adjusted temperature for freeze-thaw cycle treatment; the specimens of Group A are kept at room temperature without other treatment; after the treatment, the pressure testing machine is started, and the loading device applies a vertical load to the specimen at the set loading rate until the specimen is split and damaged.

[0091] (4) Bending strain value

[0092] In road design, it is necessary to select the appropriate asphalt mixture type based on the bending strain value and other performance indicators of asphalt, and combine it with local climatic conditions to ensure the long-term durability of the road surface. The specific bending strain value needs to refer to the specific engineering specifications or test reports, because it varies depending on the asphalt type, additives and test conditions.

[0093] Test method: The plate-shaped specimen is formed by the wheel rolling method, and then cut into prismatic beam specimens of specified size, with a length of 250mm, a width of 30mm, a height of 35mm, and a span of 200mm. Under the condition of 15℃±0.5℃, the specimen is placed on the support of the universal material testing machine, and a concentrated load is applied at a certain loading rate at the mid-span position until the specimen is destroyed. During the test, the maximum displacement value at the mid-span position is recorded, and the bending strain value is calculated by the formula ε=3δmax / (ah).

[0094] Table 1. Performance comparison between the examples of the present invention and the comparative examples

[0095]

[0096] As can be seen from Table 1, Examples 1 to 3 have excellent overall performance in various performance indicators, which is due to the use of bio-based polyurethane resin asphalt and the reasonable ratio and mixing process of various raw materials. Although different raw material selection and ratio adjustment will cause certain fluctuations in various performance indicators, they can still be maintained at a good level and meet the requirements of high-performance sustainable road mixtures.

[0097] Since Comparative Example 1 does not use bio-based polyurethane resin asphalt, the various performance indicators are significantly lower than those of the embodiment, indicating that bio-based polyurethane resin asphalt plays a vital role in improving the performance of the mixture, and can significantly enhance the structural stability, water erosion resistance, freeze-thaw resistance, compressive strength, bending resistance, etc. of the mixture.

[0098] Comparative Example 2 does not use the composite regeneration agent, and its various performance indicators are also lower than those of the embodiment, indicating that the composite regeneration agent has an important influence on the performance recovery of old asphalt materials and the improvement of the overall performance of the mixture, and helps to maintain the good performance of the mixture under various working conditions.

[0099] In summary, the use of bio-based polyurethane resin asphalt in conjunction with waste asphalt and steel slag to prepare road mixtures, and the rational use of composite regeneration agents, can effectively improve the various properties of the mixture, making it more suitable for high-performance sustainable road engineering construction.

[0100] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the embodiments is to facilitate ordinary technicians in this technical field to understand and use the invention. It is obvious that those familiar with the technology in this field can easily make various modifications to these embodiments and apply the general principles described here to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A mixture of bio-based resin asphalt, waste asphalt and steel slag, characterized in that: The raw materials of the mixture include, by mass: 40-70 parts of steel slag aggregate, 40-70 parts of old asphalt, 4-8 parts of bio-based polyurethane resin, 2-4 parts of composite regeneration agent, 10-20 parts of base asphalt; The steel slag aggregate includes one or more of converter steel slag, electric furnace steel slag, and open-hearth steel slag; The asphalt waste material comes from the waste asphalt mixture generated during road construction and maintenance; The bio-based polyurethane resin is obtained by reacting vegetable oil with polyol and isocyanate; The composite regeneration agent includes plant extracts, microbial fermentation products, functional additives, and aromatic oil; The base asphalt is 70A base asphalt.

2. The mixture of bio-based resin asphalt, waste asphalt and steel slag according to claim 1, characterized in that: The free calcium oxide content of the steel slag aggregate is not higher than 1.7%, and the polishing value is not lower than 45.

3. The mixture of bio-based resin asphalt, waste asphalt and steel slag according to claim 1, characterized in that: The vegetable oil includes at least one of tung oil, linseed oil, castor oil, soybean oil, and palm oil; the polyol includes one or more of trimethylolethane, dipentaerythritol, polycarbonate polyol, and butanediol; the isocyanate includes one or more of p-phenylene diisocyanate, adamantane diisocyanate, isophorone diisocyanate, toluene diisocyanate, or hexamethylene diisocyanate.

4. The mixture of bio-based resin asphalt, waste asphalt and steel slag according to claim 1, characterized in that: The preparation of the bio-based polyurethane resin comprises the following steps: using vegetable oil as a starting material, subjecting the vegetable oil to an ester exchange reaction with a polyol at a temperature of 150° C. to 180° C. to obtain a first intermediate product; subjecting the first intermediate product to an addition polymerization reaction with an isocyanate at a temperature of 40° C. to 60° C. to obtain a bio-based polyurethane resin; The mixing molar ratio of the vegetable oil to the polyol is 1:1-3; the mixing molar ratio of the first intermediate product to the isocyanate is 1:0.8-1.

5.

5. The mixture of bio-based resin asphalt, waste asphalt and steel slag according to claim 1, characterized in that: The plant extract is ginkgo leaf extract; the microbial fermentation product is bacillus fermentation product; the functional additives are butylated hydroxyanisole, butylated hydroxytoluene and N,N'-di-sec-butyl-p-phenylenediamine; The mixing mass ratio of the plant extract, microbial fermentation product, functional additive and aromatic oil is (2-3):(1-2):(4-5):(1-2).

6. A method for preparing a mixture of bio-based resin asphalt, waste asphalt and steel slag, characterized in that: The preparation method comprises the following steps: S1. Pre-treat the steel slag aggregate and asphalt waste material according to the raw material ratio as described in any one of claims 1 to 5; prepare the bio-based polyurethane resin; prepare the composite regeneration agent; and set aside; S2. The composite regeneration agent is fully mixed with the pretreated asphalt waste material to obtain the regenerated asphalt waste material for standby use; S3. The bio-based polyurethane resin is mixed with the base asphalt to obtain a bio-based polyurethane resin asphalt; S4. Add the recycled asphalt obtained in S2, the bio-based polyurethane resin asphalt and steel slag obtained in S3 into a mixing device, and stir them evenly to obtain a mixture of bio-based resin asphalt, waste asphalt and steel slag.

7. The method for preparing a mixture of bio-based resin asphalt, waste asphalt and steel slag according to claim 6, characterized in that: The pretreatment process of the steel slag aggregate in step S1 is: by screening, removing oversized particles and impurities therein, to obtain qualified steel slag aggregate, the specific particle size of which ranges from 0 mm to 10 mm, and is not 0.

8. The method for preparing a mixture of bio-based resin asphalt, waste asphalt and steel slag according to claim 6, characterized in that: The pretreatment of the asphalt waste material in step S1 includes the following steps: collecting the asphalt waste material, removing impurities such as stones and soil therein through mechanical treatment means, and obtaining relatively pure asphalt waste material particles with a particle size range of 0mm to 15mm, and not 0; the mechanical treatment means at least includes any one of crushing and screening.

9. The method for preparing a mixture of bio-based resin asphalt, waste asphalt and steel slag according to claim 6, characterized in that: The stirring speed in step S4 is in the range of 200 to 600 rpm, the specific temperature is 40 to 60° C., and the specific time is 1 to 3 hours.

10. An application of bio-based resin asphalt in combination with a mixture of waste asphalt and steel slag, characterized in that: The application refers to the application of the mixture in the technical field of road engineering materials, and the mixture is used for paving sustainable roads.

Images