A rap mixed regeneration mixture based on desulfurized rubber modified regenerant and a preparation method thereof

Abstract

The application relates to the field of road engineering materials, and particularly discloses a RAP-mixed regeneration mixture based on a devulcanized rubber modified regenerant and a preparation method thereof. The preparation method of the RAP-mixed regeneration mixture comprises the following steps: mixing new aggregate, new asphalt, premix and a chemical crosslinking agent at a temperature of 110-125 DEG C, wherein the premix is prepared from RAP and a devulcanized rubber modified regenerant; the devulcanized rubber modified regenerant is prepared from the following raw materials: 30-60 parts of devulcanized rubber, 30-60 parts of base regeneration waste biological oil, 5-20 parts of active compatibilizing resin, 0.5-5 parts of warm-mixing surfactant and 0.5-3 parts of crosslinking catalyst. The application can significantly reduce energy consumption, and through multiple means such as deep softening, elastic recovery and formation of a chemical crosslinking network, the high-temperature stability, fatigue resistance and low-temperature crack resistance of the RAP-mixed regeneration mixture are synergistically improved, and high-value resource utilization is realized.

Description

Technical Field

[0001] This application relates to the technical field of road engineering materials, and in particular to a regenerated compound based on desulfurized rubber modified regenerator and its preparation method. Background Technology

[0002] Semi-rigid base asphalt pavement is the most typical structural type for high-grade highways and urban roads. With the increase in highway mileage and the expansion of cities, asphalt pavement gradually ages, leading to a decline in performance. Maintenance and repair have become a major task in road engineering. A large amount of waste is generated during the maintenance and repair process. Recycling and reusing waste will reduce environmental pollution, reduce the amount of new materials used, and achieve the effect of saving resources and reducing costs.

[0003] Existing technologies for reusing recycled asphalt pavement (RAP) often involve adding a certain amount of modifiers and regenerators to the old material to physically or chemically modify it. For example, existing patents CN111499273A uses asbestos shreds, CN108911590A uses steel slag, and CN110981288A uses waste cooking oil, etc., all of which modify and regenerate the old material, restoring its road performance. Compared to these methods, adding RAP offers advantages such as lower cost, higher old material content, and better road performance. After adding RAP, the viscosity, penetration index, ductility, and other indicators of petroleum asphalt are improved, and the high-temperature stability, low-temperature crack resistance, durability, and fatigue resistance of the mixture are all enhanced. Simultaneously, the high elasticity of the old rubber in RAP significantly improves vehicle ride comfort; the carbon black in the old rubber keeps the pavement black for a long time, increasing the contrast between the pavement color and road markings, thus improving driving safety. Currently, the method of using RAP (such as existing patents CN110218461A and CN108117305A, which use rubber powder, rubber oil or directly use rubber asphalt) involves directly adding it to new aggregates and base asphalt for co-mixing to obtain rubber recycled asphalt mixture.

[0004] However, RAP has certain drawbacks in the recycling of asphalt mixtures. First, the old rubber is difficult to swell when mixed with asphalt. The rubber powder and asphalt are only physically bonded, and the rubber does not form a network structure but is dispersed in the asphalt as a filler, resulting in poor crack resistance of the mixture. Second, the old rubber has poor compatibility with asphalt and poor high-temperature stability. It is easy to generate harmful gases during construction, which endangers the health of construction workers. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a regenerated compound based on a desulfurized rubber modifier and its preparation method.

[0006] In a first aspect, this application provides a method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier, comprising the following steps: S1. Pretreatment: The RAP is crushed and screened, and the quality of the old asphalt in the RAP is tested and recorded as M1; S2. Activation: The sieved RAP obtained in S1 and the desulfurized rubber modified regenerator are mixed together and stirred at a temperature of 100-125℃ for 80-100s to obtain a premix, wherein the amount of desulfurized rubber modified regenerator is 10-25% of M1, denoted as M2. S3. Blending: The new aggregate, new asphalt, the premix obtained in S2, and the chemical crosslinking agent are mixed at a temperature of 110-125℃ for 80-100s to obtain a RAP-blended recycled mixture with an asphalt-aggregate ratio of 4.5-6.5%, wherein the weight ratio of the premix to the new aggregate is (5-7):(3-5), and the mass of the new aggregate accounts for 30-45wt% of the total mass of the new aggregate, asphalt, and premix, and the amount of chemical crosslinking agent added is 1.0-2.5% of M2.

[0007] Preferably, in S3, the amount of new asphalt added is denoted as M3, and is calculated according to the asphalt-aggregate ratio and M1.

[0008] By adopting the above technical solution, this application first crushes and screens the recycled asphalt pavement waste (RAP), preferably screening it to four grades: 0-3mm, 3-5mm, 5-10mm, and above 10mm (in actual operation, it can also be screened to three grades: 0-5mm, 5-10mm, and above 10mm, depending on different needs). Then, the asphalt content and gradation composition of each grade of RAP are determined by extraction or combustion methods. Based on the gradation type of the target mixture (such as AC, SMA, ATB, etc.), each grade of RAP is combined with new aggregate. Gradation design: RAP after screening in a certain proportion and desulfurized rubber modified regenerator are blended together. The amount of desulfurized rubber modified regenerator is controlled to be 10-25% of the mass of old asphalt in RAP. A premix with good compatibility with new asphalt and new aggregate is obtained. Then, the amount of new asphalt added is determined according to the asphalt-aggregate ratio and the amount of new aggregate. The new aggregate, new asphalt, the obtained premix and chemical crosslinking agent are mixed at a relatively low temperature of 110-125℃, which can effectively suppress the generation of harmful gases without affecting the mixing effect.

[0009] Overall, the preparation method of this application significantly reduces energy consumption and suppresses the generation of harmful gases. At the same time, it synergistically improves the high-temperature stability, fatigue resistance and low-temperature crack resistance of high RAP content recycled mixtures through the deep softening of aged asphalt by the recycling agent, the elastic recovery of desulfurized rubber particles and the formation of chemical cross-linking networks, thus realizing the high-value-added resource utilization of waste tires, waste oils and RAP.

[0010] Preferably, the chemical crosslinking agent in S3 includes any one of sulfur, organic peroxide, polyamine and acid anhydride curing agent, and also includes trans polyoctene rubber or trans polyisoprene rubber.

[0011] By adopting the above technical solution, this application uses any one of sulfur, organic peroxide, polyamine and acid anhydride curing agent and any one of trans polyoctene rubber or trans polyisoprene rubber in a weight ratio of 1:(15-30) as a chemical crosslinking agent, which can provide additional cohesive force and network support in the later stage of mixing, and synergistically strengthen the three-dimensional network with the crosslinking agent.

[0012] Preferably, in S2, the desulfurized rubber modified regenerator has a Burley viscosity of 5000-15000 mPa·s at 25°C.

[0013] Preferably, the desulfurized rubber modified regenerator is prepared from the following raw materials in parts by weight: 30-60 parts of desulfurized rubber; Basic recycled waste bio-oil is divided into 30-60 parts; 5-20 parts of active compatibilizing resin; Add 0.5-5 parts of surfactant to warm-stir. Crosslinking catalyst 0.5-3 parts; The desulfurized rubber is obtained by oxygen-free desulfurization and regeneration of waste tire rubber powder, with a sol content of 70-85% and Mooney viscosity <10ML.

[0014] Preferably, the basic recycled waste bio-oil includes one or more of epoxidized soybean oil, waste engine oil, and kitchen waste oil.

[0015] Preferably, the active compatibilizing resin includes one or more of C5 copolymer petroleum resin, C9 copolymer petroleum resin, terpene resin, or epoxidized rosin resin.

[0016] Preferably, the warm-stirring surfactant includes one or more of amine, alkanolamine, or polyether surfactants.

[0017] Preferably, the crosslinking catalyst is one or more of organozinc, organocobalt, or tertiary amine compounds.

[0018] By adopting the above technical solution, the desulfurized rubber of this application is obtained by oxygen-free desulfurization and regeneration of waste tire rubber powder, with a sol content of 70-85% and a Mooney viscosity of less than 10ML, exhibiting excellent flowability and reactivity. The desulfurized rubber modified regenerator is actually a blend of basic recycled waste bio-oil, desulfurized rubber, and various functional additives (active compatibilizing resin, warm-stirring surfactant, and crosslinking catalyst). The desulfurized rubber modified regenerator has a Burley viscosity of 5000-15000 mPa·s at 25℃, and this viscosity range allows it to still have good flowability and permeability at lower temperatures of 110-125℃.

[0019] By adopting the above technical solution Secondly, this application also provides a RAP-doped recycled compound prepared by the above-mentioned method for preparing RAP-doped recycled compound based on desulfurized rubber modified regenerator.

[0020] In summary, this application has the following beneficial technical effects: The preparation method of this application achieves high utilization of RAP (the amount of which reaches 100% or more of the amount of new aggregate) under the premise of significantly reducing the mixing temperature to 110-125℃, which has significant energy-saving and environmental protection benefits. The desulfurized rubber modified regenerator can effectively soften the old asphalt in RAP and can also become an elastic reinforcing component through subsequent cross-linking, which greatly improves the fatigue resistance and crack resistance of the mixture. The preparation method of this application is simple and has a reasonable operation process, thus providing a new way for the high-value-added resource utilization of waste tire rubber powder and RAP. Detailed Implementation

[0021] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0022] Preparation Example 1 The preparation method of desulfurized rubber modified regenerator includes the following steps: ① 10 kg of waste tire rubber powder (40 mesh) and 0.3 kg of activator (a mixture of zinc oxide and stearic acid) were stirred and reacted in an oxygen-free reactor at a temperature of 220°C under nitrogen protection for 2 hours. After cooling, desulfurized rubber with a sol content of 75% and a Mooney viscosity of 5 ml was obtained. ② Mix 3 kg of epoxidized soybean oil and 1.5 kg of refined kitchen waste oil and heat to 120°C. Then add 4.5 kg of the desulfurized rubber obtained in step ①. Shear and disperse the mixture in a high-speed shear machine at 3000 rpm for 30 min. Cool the mixture to 80°C, continue stirring, and add 0.8 kg of C9 copolymer petroleum resin, 0.15 kg of aliphatic polyetheramine, and 0.05 kg of zinc dimethyl dithiocarbamate. Stir until completely dissolved, forming a uniform, viscous black gel. Its Brookfield viscosity at 25°C is 10250 mPa·s, which is the desulfurized rubber modified regenerator.

[0023] Preparation Example 2 The preparation method of the desulfurized rubber modified regenerator differs from that of Preparation Example 1 in that the C9 copolymer petroleum resin in step ② is replaced with epoxidized rosin resin (provided by Shangrao Sinan Resin Co., Ltd., brand name SNS-138), while the rest is the same as that of Preparation Example 1.

[0024] Preparation Example 3 The preparation method of the desulfurized rubber modified regenerator differs from that of Preparation Example 1 in that the C9 copolymer petroleum resin in step ② is replaced with a polyether surfactant (provided by Jiangsu Haian Petrochemical Plant, brand name TPE-1000), while the rest is the same as that of Preparation Example 1.

[0025] Example 1 A method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier includes the following steps: S1. Pretreatment: RAP is crushed and sieved into four grades: 0-3mm, 3-5mm, 5-10mm, and over 10mm. Extraction and analysis are then performed to obtain: The asphalt content is 6.8 wt% for 0-3mm grade, 5.8 wt% for 3-5mm grade, 5.3 wt% for 5-10mm grade, and 4.5 wt% for grade over 10mm. First, the total RAP usage is determined to be 60kg. Based on the AC-16C type gradation as the design target, the composition of each RAP grade is as follows: The 0-3mm range accounts for 12kg, the 3-5mm range accounts for 15kg, the 5-10mm range accounts for 15kg, and the range above 10mm accounts for 18kg. At the same time, it was determined that the total amount of new aggregate to be added later would be 40 kg, with the following specific composition: Manufactured sand accounts for 12kg, 5-10mm grade accounts for 10kg, and 10-15mm grade accounts for 18kg; Based on the above asphalt content and gradation, the mass of old asphalt M1 is calculated to be M1 = 12kg × 6.8wt% + 15kg × 5.8wt% + 15kg × 5.3wt% + 18kg × 4.5wt% = 3.29kg; S2. Activation: Preheat each grade of RAP obtained in S1 to 120°C, then add them to the mixing pot according to their respective amounts, premix at 120°C for 60 seconds, then add the desulfurized rubber modified regenerator obtained in Preparation Example 1 with an amount of M2 (M2=M1×20%=0.658kg), and continue to mix at 120°C for 90 seconds to allow the desulfurized rubber modified regenerator to fully coat and penetrate the RAP, thus obtaining the premix. S3. Blending: The amount of new aggregate is determined to be 40kg, the amount of premix is ​​60kg, the amount of chemical crosslinking agent is 13.16g (M2×2%), the asphalt-aggregate ratio is set to 4.9%, and the total amount of asphalt is calculated to be 4.74kg. Therefore, the amount of new asphalt is M3=4.74kg-M1=1.45kg. 1.45 kg of new asphalt, 40 kg of new aggregate, and 60 kg of premix were added to a pot and mixed and heated to 130°C. At the same time, 13.16 g of chemical crosslinking agent (dicumyl peroxide and trans polyoctene rubber in a weight ratio of 1:20) was added and mixed at 120°C for 90 seconds to obtain a RAP-blended recycled mixture.

[0026] Example 2 A method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier differs from Example 1 in that: In S1, the total amount of RAP is adjusted to 70kg, and the total amount of new aggregate is 30kg. At this time, M1=3.84kg. In S2, adjust M2 = M1 × 22% = 0.845 kg; In S3, the amount of chemical crosslinking agent used is 18.59g, which includes sulfur and trans polyoctene rubber in a weight ratio of 1:18, and the mixing temperature is adjusted to 118℃. Everything else is the same as in Example 1.

[0027] Example 3 A method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier differs from Example 1 in that: in S2, the desulfurized rubber modifier obtained in Preparation Example 1 is replaced with the desulfurized rubber modifier obtained in Preparation Example 2, and the rest is the same as in Example 1.

[0028] Example 4 A method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier differs from Example 1 in that: in S2, the desulfurized rubber modifier obtained in Preparation Example 1 is replaced with the desulfurized rubber modifier obtained in Preparation Example 3, and the rest is the same as in Example 1.

[0029] Comparative Example 1 The difference from Example 1 is as follows: The desulfurized rubber modified regenerator obtained in Example 1 of S2 was replaced with an equal amount of conventional aromatic oil regenerator (purchased from Jiangsu Subote New Material Co., Ltd.). In S3, the chemical cross-linking agent is removed, and the mixing temperature is adjusted to 165℃. Everything else is the same as in Example 1.

[0030] Comparative Example 2 The difference from Comparative Example 1 is that in S3, 14.22g of ordinary organic wax warming agent was added, and the mixing temperature was adjusted to 135℃. Everything else was the same as Comparative Example 1.

[0031] Performance testing The RAP-doped recycled mixtures prepared in Examples 1-4 and Comparative Examples 1-2 were molded into rutted plates and beam bending specimens according to specifications, and Marshall tests, freeze-thaw splitting tests, high-temperature rutting tests, and low-temperature beam bending tests were conducted. The results are shown in Table 1. Table 1 Performance Test Table

[0032] Data Analysis: As shown in Table 1, the specimens obtained after molding from the RAP-infused recycled mixtures in Examples 1-4 of this application exhibited a stability of 10.5-12.5 kN, a flow value of 33-36 / 0.1 mm, a freeze-thaw strength splitting ratio of 85-90%, and a dynamic stability of 4159-5900 cycles / mm. -1 The failure strain is 3109.8-3520.1 με, which shows that the preparation method of this application can make the RAP-doped recycled mixture have good high-temperature stability and good toughness under low-temperature conditions. It has high deformation capacity, low possibility of brittle fracture, and good low-temperature crack resistance. At the same time, the raw material contains more than half of the recycled material (RAP), which significantly reduces the manufacturing cost and effectively realizes the recycling and reuse of waste materials.

[0033] In Example 3, the C9 copolymer petroleum resin in step ② was replaced with epoxidized rosin resin. In Example 4, the C9 copolymer petroleum resin in step ② was replaced with polyether surfactant. The results showed that the overall performance of Example 1 was higher than that of Examples 3-4. It can be seen that the C9 copolymer petroleum resin, aliphatic polyether amine and zinc dimethyl dithiocarbamate achieved a good synergistic effect.

[0034] Comparative Example 1 uses a conventional thermal regeneration method, whose dynamic stability is only 3200 cycles / mm. -1 The failure strain was only 2356.3 με, while the dynamic stability of the conventional warm-stirring regeneration method used in Comparative Example 2 was only 2840 cycles·mm. -1 The failure strain was only 2140.8 με. The dynamic stability and failure strain of Example 1 were increased by 45-63% and 42-56% respectively compared with Comparative Examples 1-2, which shows that the preparation method of this application fully utilizes the powerful role of the chemical cross-linking network. At the same time, the freeze-thaw splitting strength ratio of Comparative Examples 1-2 was only 75-78%, while the freeze-thaw splitting strength ratio of Example 1 was increased by 15-20% compared with Comparative Examples 1-2, showing excellent resistance to water damage. This is due to the improved adhesion and stability of the cross-linking network by the desulfurized rubber modifier and regenerator.

[0035] More importantly, the performance of Comparative Example 2 (conventional warm-mix recycling method) was slightly worse than that of Comparative Example 1 (conventional hot recycling method). This reflects the limitation of simply lowering the temperature but failing to improve the performance of the mixture. However, this application (Examples 1-4) achieved a comprehensive improvement in performance at a lower temperature, which fully demonstrates that the desulfurized rubber modified regenerator and asphalt can achieve chemical cross-linking under warm mixing, thereby synergistically improving the overall performance and effectively reducing the mixing temperature.

[0036] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier, characterized in that, Includes the following steps: S1. Pretreatment: The RAP is crushed and screened, and the quality of the old asphalt in the RAP is tested and recorded as M1; S2. Activation: The sieved RAP obtained in S1 and the desulfurized rubber modified regenerator are mixed together and stirred at a temperature of 100-125℃ for 80-100s to obtain a premix, wherein the amount of desulfurized rubber modified regenerator is 10-25% of M1, denoted as M2. S3. Blending: The new aggregate, new asphalt, the premix obtained in S2, and the chemical crosslinking agent are mixed at a temperature of 110-125℃ for 80-100s to obtain a RAP-blended recycled mixture with an asphalt-aggregate ratio of 4.5-6.5%, wherein the weight ratio of the premix to the new aggregate is (5-7):(3-5), and the mass of the new aggregate accounts for 30-45wt% of the total mass of the new aggregate, asphalt, and premix, and the amount of chemical crosslinking agent added is 1.0-2.5% of M2.

2. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 1, characterized in that, In S3, the amount of new asphalt added is denoted as M3, and is calculated according to the asphalt-aggregate ratio and M1.

3. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 1, characterized in that, The chemical crosslinking agent in S3 includes any one of sulfur, organic peroxide, polyamine, and acid anhydride curing agents, and also includes trans polyoctene rubber or trans polyisoprene rubber.

4. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 1, characterized in that, In S2, the desulfurized rubber modified regenerator has a Burley viscosity of 5000-15000 mPa·s at 25°C.

5. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 1, characterized in that, The desulfurized rubber modified regenerator is prepared from the following raw materials in parts by weight: 30-60 parts of desulfurized rubber; Basic recycled waste bio-oil is divided into 30-60 parts; 5-20 parts of active compatibilizing resin; Add 0.5-5 parts of surfactant to warm-stir. Crosslinking catalyst 0.5-3 parts; The desulfurized rubber is obtained by oxygen-free desulfurization and regeneration of waste tire rubber powder, with a sol content of 70-85% and Mooney viscosity <10ML.

6. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 5, characterized in that, The basic recycled waste bio-oil components include one or more of epoxidized soybean oil, waste engine oil, and kitchen waste oil.

7. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 5, characterized in that, The active compatibilizing resin includes one or more of C5 copolymer petroleum resin, C9 copolymer petroleum resin, terpene resin, or epoxidized rosin resin.

8. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 5, characterized in that, The warm-stirring surfactant includes one or more of amine, alkanolamine, or polyether surfactants.

9. The method for preparing a RAP-modified recycled compound based on a desulfurized rubber modifier according to claim 5, characterized in that, The crosslinking catalyst is one or more of organozinc, organocobalt, or tertiary amine compounds.

10. A RAP-doped recycled compound prepared by the method of any one of claims 1-9 based on a desulfurized rubber modifier.

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