A recycling process based on recycled asphalt pavement materials

Abstract

The present invention discloses a recycling and regeneration process based on old asphalt pavement materials, belonging to the technical field of asphalt pavement regeneration, and comprising the following steps: S1. Heat and stir epoxy resin and petroleum asphalt evenly, then add active diluent and accelerator and stir evenly to obtain an epoxy component; S2. Stir and heat isocyanate trimer to a constant temperature, and slowly drop cardanol into it. After the dropping of cardanol is completed, keep warm for reaction. After the isocyanate trimer and cardanol completely react, a blocked isocyanate trimer is obtained; S3. Mix the blocked isocyanate trimer with the epoxy component to obtain a cementitious material; S4. Stir and heat the graded asphalt old material, then heat the cementitious material, continue to stir evenly, and spread the mixture on the road surface. After leveling, compaction and curing, a recycled asphalt pavement is formed; The present invention can improve the utilization rate of old asphalt pavement resources and improve the mechanical strength of the recycled asphalt pavement.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt pavement recycling, and particularly relates to a recycling process based on recycled asphalt pavement materials. Background Art

[0002] The laying of asphalt pavement requires a large amount of non-renewable resources such as petroleum asphalt and sand and stone materials. Recycling recycled asphalt pavement materials can reduce the demand for new asphalt materials, which is of great significance for protecting limited natural resources and promoting sustainable development.

[0003] At present, the recycling of asphalt pavement is mainly divided into two methods. One is to heat and mill the asphalt pavement on-site, then add new asphalt, recycling agent and new stone materials, etc., and then mix and pave on-site by a combined recycling equipment to form a recycled asphalt pavement; the other is to transport the recycled asphalt pavement materials back to the asphalt mixing plant, reheat and mix them, add new asphalt and new stone materials to form a new hot mix asphalt mixture, and then use the conventional asphalt concrete construction method for paving and rolling to form a recycled asphalt pavement; however, a relatively large amount of new asphalt, new stone materials and other materials usually need to be added to the recycled asphalt pavement, and the utilization rate of recycled asphalt pavement materials is still relatively low.

[0004] Based on the above situation, Chinese patent document with publication number CN101845227A discloses a common asphalt recycling agent and its preparation and application. The common asphalt recycling agent is mainly prepared by heating, mixing and stirring matrix asphalt, recycling oil, plasticizer and high-temperature stabilizer; the specific preparation method is: first heat the matrix asphalt at 115°C - 135°C, then heat and stir evenly the recycling oil, plasticizer and high-temperature stabilizer at 115°C - 135°C to obtain a mixture, and finally stir the matrix asphalt and the mixture at 115°C - 135°C and cool to obtain the common asphalt recycling agent; when applying, first heat the aged asphalt at 110°C - 135°C, then add the common asphalt recycling agent to it, and the addition amount is more than 30% of the aged asphalt amount, and then stir at 100°C - 110°C to obtain recycled asphalt.

[0005] The above patent document discloses a method for making recycled asphalt from aged asphalt. This method is to make a common asphalt recycling agent from matrix asphalt, recycling oil, plasticizer and high-temperature stabilizer and then mix it with aged asphalt to form recycled asphalt. After the recycled asphalt undergoes conventional asphalt pavement laying operations, a new asphalt pavement can be formed. However, the addition amount of the common asphalt recycling agent needs to be more than 30% of the aged asphalt amount. A relatively large amount of new materials are consumed during the recycling process of asphalt pavement, and the utilization rate of recycled asphalt pavement materials is not high. Therefore, there is still room for improvement in this method of making recycled asphalt. Summary of the Invention

[0006] In view of the technical deficiencies in the background art, the present invention proposes a recycling process based on waste asphalt pavement materials, which solves the above technical problems and meets the actual needs. The specific technical solutions are as follows:

[0007] A recycling process based on waste asphalt pavement materials, comprising the following steps:

[0008] S1. Put epoxy resin and petroleum asphalt into a stirring kettle, heat and stir evenly at the same time, then add an active diluent and a promoter and stir evenly, and then cool down to room temperature to obtain an epoxy component;

[0009] S2. Add isocyanate trimer into a reaction kettle and heat and stir. After the isocyanate trimer is heated to a constant temperature, slowly drip cardanol into the reaction kettle through a dropping funnel. After the cardanol is added dropwise, keep the temperature for reaction. After the isocyanate trimer and cardanol in the reaction kettle react completely, a blocked isocyanate trimer is obtained;

[0010] S3. After the blocked isocyanate trimer is cooled down to room temperature, mix it with the epoxy component to obtain a cementitious material;

[0011] S4. Crush and screen the waste asphalt pavement materials to obtain graded waste asphalt materials. Stir and heat the graded waste asphalt materials, then heat the cementitious material. After continuing to stir evenly, spread the mixture on the road surface and form a recycled asphalt pavement after leveling, compaction and curing.

[0012] As a further technical solution of the present invention, the epoxy component comprises the following components by mass percentage: 70% - 85% of epoxy resin, 5% - 15% of petroleum asphalt, 5% - 15% of active diluent, and 0.5% - 1% of promoter.

[0013] As a further technical solution of the present invention, during the process of keeping the temperature for reaction of the isocyanate trimer and cardanol in the reaction kettle, detect the content of isocyanate groups in the product in the reaction kettle at regular intervals. When the mass percentage of isocyanate groups is less than 0.05%, it is determined that the isocyanate trimer and cardanol in the reaction kettle have reacted completely.

[0014] As a further technical solution of the present invention, in step S2, the temperature for heating the isocyanate trimer in the reaction kettle is 70 - 80°C, and the temperature for keeping the temperature for reaction of the isocyanate trimer and cardanol in the reaction kettle is 70 - 90°C, and the holding time is 1 - 4 h.

[0015] As a further technical solution of the present invention, the isocyanate trimer is selected from one or a mixture of two of hexamethylene diisocyanate trimer and isophorone diisocyanate trimer.

[0016] As a further technical solution of the present invention, in step S2, the mass ratio of the hexamethylene diisocyanate trimer to the cashew phenol is 1:(0.6 - 0.7).

[0017] As a further technical solution of the present invention, in step S2, the mass ratio of the isophorone diisocyanate trimer to the cashew phenol is 1:(0.5 - 0.6).

[0018] As a further technical solution of the present invention, in step S3, the mass ratio of the blocked isocyanate trimer to the epoxy component is 1:(1.5 - 2).

[0019] As a further technical solution of the present invention, in step S4, the heating temperature of the old asphalt material is 120 - 140 °C;

[0020] The recycled asphalt pavement includes the following components by mass percentage: 93% - 98% of old asphalt material, 2% - 7% of cementitious material.

[0021] As a further technical solution of the present invention, the epoxy resin is selected from one or more of E20 epoxy resin, E44 epoxy resin, and E51 epoxy resin;

[0022] The petroleum asphalt is selected from one or a mixture of two of 70# petroleum asphalt and 90# petroleum asphalt;

[0023] The active diluent is selected from one or more of C12 - 14 alkyl glycidyl ether, butyl glycidyl ether, and benzyl glycidyl ether;

[0024] The accelerator is selected as γ - glycidyl ether oxypropyl trimethoxysilane.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention makes recycled asphalt from cementitious material and old asphalt material. The blocked isocyanate trimer is used as a cross - linker in the cementitious material, so that the cementitious material needs a relatively high temperature to cross - link and cure. This improves the convenience of the cementitious material during daily storage and transportation, and can also improve the bonding strength and toughness after curing of the cementitious material, which is beneficial to improving the mechanical strength of the recycled asphalt pavement. In addition, the present invention does not require component analysis of the old asphalt material and has a high utilization rate of the old asphalt material, simplifies the rebirth operation of the old asphalt material, and efficiently recycles the old asphalt pavement resources. Specific Embodiments

[0027] The embodiments of the present invention will be described below in conjunction with relevant embodiments. The embodiments of the present invention are not limited to the following embodiments, and the present invention relates to relevant necessary components in the technical field, which should be regarded as well-known technologies in the technical field and can be known and mastered by those skilled in the technical field.

[0028] A recycling and regeneration process based on old asphalt pavement materials includes the following steps:

[0029] S1. Put epoxy resin and petroleum asphalt into a stirring kettle, heat and stir evenly at the same time, then put in an active diluent and a promoter and stir evenly, and then cool down to room temperature to obtain an epoxy component;

[0030] S2. Add isocyanate trimer into a reaction kettle and heat and stir. After the isocyanate trimer is heated to a constant temperature, slowly drip cardanol into the reaction kettle through a dropping funnel. After the cardanol is added dropwise, keep the temperature for reaction. After the isocyanate trimer and cardanol in the reaction kettle react completely, a blocked isocyanate trimer is obtained;

[0031] S3. After the blocked isocyanate trimer is cooled down to room temperature, mix it with the epoxy component to obtain a cementing material;

[0032] S4. Crush and screen the old asphalt pavement materials to obtain graded asphalt old materials. Stir and heat the graded asphalt old materials, then add the cementing material. After continuing to stir evenly, spread the mixture on the road surface, and then form a recycled asphalt pavement after leveling, compaction and curing.

[0033] The old asphalt pavement materials of the present invention are obtained by milling old asphalt pavements. After the old asphalt pavement materials are crushed and screened, asphalt old materials of different sizes are formed. These asphalt old materials can be divided into four grades according to size: greater than 10 mm, 10 - 5 mm, 5 - 1 mm, and less than 1 mm. After these four grades of asphalt old materials are mixed in an appropriate proportion, graded asphalt old materials are obtained. In the graded asphalt old materials, the mass percentages of the asphalt old materials with sizes greater than 10 mm, 10 - 5 mm, 5 - 1 mm, and less than 1 mm are 35% - 45%, 25% - 35%, 15% - 25%, and 5% - 15% respectively. By reasonably grading and mixing asphalt old materials of different sizes to obtain graded asphalt old materials, small particle asphalt old materials can better fill the gaps between large particle asphalt old materials, which is beneficial to improving the compactness inside the recycled asphalt pavement and mechanical strengths such as compressive strength and tensile strength, and can also improve the uniformity of the mixture of the graded asphalt old materials and the cementing material.

[0034] The cementitious material of the present invention is obtained by mixing a blocked isocyanate trimer as a crosslinking agent with an epoxy component. The isocyanate groups in the blocked isocyanate trimer are blocked by cardanol, so that it can remain stable under certain conditions and does not react with epoxy resin, which can improve the convenience of the cementitious material during daily storage and transportation. When the reaction is required, the blocked isocyanate trimer restores its reaction activity by deblocking. The deblocking temperature of the blocked isocyanate trimer is 120 °C. When the temperature rises above 120 °C, the isocyanate groups in the blocked isocyanate trimer will restore their reaction activity and promote the curing of epoxy resin through crosslinking reaction. The cementitious component formed by the curing reaction of the blocked isocyanate trimer and epoxy resin has excellent bonding strength and toughness, which is beneficial to improving the mechanical strength of the recycled asphalt pavement. And due to the presence of a large number of polar hydroxyl groups in cardanol, it has a good wetting degree for graded asphalt old materials, which is conducive to the uniform wrapping of the graded asphalt old materials by the cementitious material. The granular graded asphalt old materials are adhered to each other through the cementitious material to form recycled asphalt. After the recycled asphalt is evenly spread on the surface of the road base and then leveled and compacted, a prototype of the recycled asphalt pavement is formed. The curing of the blocked isocyanate trimer and the epoxy component makes the recycled asphalt form a solid whole, thus obtaining a solid recycled asphalt pavement.

[0035] It should be further noted that the graded asphalt old materials in the recycled asphalt are mainly formed by being wrapped by the cementitious material and then cured by heating and crosslinking. Therefore, there is no need to consider operations such as the content analysis of oil, gum, asphaltine, etc. during the regeneration of traditional asphalt old materials. Only the asphalt old materials need to be crushed, screened, and graded, which has a positive significance for the promotion and application of the efficient utilization of old recycled asphalt pavement resources.

[0036] As one of the preferred embodiments of the present invention, the epoxy component includes the following components by mass percentage: 70% - 85% of epoxy resin, 5% - 15% of petroleum asphalt, 5% - 15% of active diluent, and 0.5% - 1% of accelerator; the epoxy resin is selected from one or more of E20 epoxy resin, E44 epoxy resin, and E51 epoxy resin; the petroleum asphalt is selected from one or a mixture of two of 70# petroleum asphalt and 90# petroleum asphalt; the active diluent is selected from one or more of C12 - 14 alkyl glycidyl ether, butyl glycidyl ether, and benzyl glycidyl ether; the accelerator is selected as γ - glycidyl ether oxypropyltrimethoxysilane.

[0037] In the epoxy component of the present invention, the epoxy resin has excellent mechanical properties, chemical properties, and thermal stability, which can significantly improve the shear resistance, cementitious property, adhesion property, and elastic modulus of the recycled asphalt pavement, thus making the recycled asphalt pavement more stable and durable. During the curing process of the recycled asphalt, the epoxy resin can undergo a crosslinking curing reaction with isocyanate to form a stable network structure and serve as the basis for ensuring the strength of the recycled asphalt pavement.

[0038] Furthermore, petroleum asphalt is the main film-forming substance of recycled asphalt. After forming a film, it will cover the surface of the graded asphalt old material, playing a role of isolation and protection. Petroleum asphalt itself has excellent waterproof performance, which can effectively prevent the penetration of moisture and improve the waterproof performance of the recycled asphalt pavement. Petroleum asphalt can resist the erosion of chemical substances, enabling the recycled asphalt pavement to have a certain resistance to corrosive substances such as acids, alkalis, and salts.

[0039] Furthermore, the reactive diluent can reduce the viscosity of epoxy resin, improve the workability and reduce the construction difficulty, making the recycled asphalt easier to process and handle. The reactive diluent not only plays a diluting role but also participates in the crosslinking and curing reaction of epoxy resin and isocyanate, becoming a part of the cured product network structure, improving the mechanical properties, adhesion, and flexibility of the recycled asphalt pavement.

[0040] Furthermore, the accelerator can accelerate the crosslinking and curing reaction between epoxy resin and isocyanate, shorten the curing time and improve the processing efficiency. By adding an appropriate amount of accelerator, the process and degree of the crosslinking and curing reaction can be regulated, so as to obtain a recycled asphalt pavement with higher performance.

[0041] As one of the preferred embodiments of the present invention, during the reaction of isocyanate trimer and cardanol in the reaction kettle under heat preservation, the content of isocyanate groups in the product in the reaction kettle is detected every once in a while. When the mass percentage of isocyanate groups is less than 0.05%, it is determined that the isocyanate trimer and cardanol in the reaction kettle have completely reacted; in order to judge whether the isocyanate trimer and cardanol in the reaction kettle have completely reacted, usually after 1 h of reaction under heat preservation, the content of isocyanate groups in the substances in the reaction kettle is detected every 10 min or 15 min or 20 min or 30 min. The detection method can usually adopt chemical titration or chromatography. When the detected content of isocyanate groups is lower than 0.05%, it means that most of the isocyanate trimer in the reaction kettle has completed the blocking reaction, and only a very small amount of isocyanate trimer has not completed the blocking reaction. This part of the isocyanate trimer will not cause the recycled asphalt to cure at room temperature. Therefore, it can be regarded that the isocyanate trimer and cardanol in the reaction kettle have completely reacted, and the reaction kettle can be cooled to end the reaction, and a highly pure blocked isocyanate trimer can be obtained from the reaction kettle.

[0042] As one of the preferred embodiments of the present invention, in step S2, the temperature at which the isocyanate trimer is heated in the reactor is 70-80°C, and the temperature at which the isocyanate trimer and cardanol are kept warm in the reactor for reaction is 70-90°C, and the insulation time is 1-4h; during the blocking reaction of the isocyanate trimer and cardanol in the reactor, heating the isocyanate trimer can promote its activation and ensure the normal progress of the blocking reaction, and slowly adding cardanol can control the rate of the blocking reaction to avoid excessively violent reaction, which may lead to a decrease in product quality or the generation of by-products. Subsequently, the unreacted isocyanate trimer and cardanol continue to react by keeping warm to ensure that the two react fully, thereby improving the purity and quality of the product.

[0043] As one of the preferred embodiments of the present invention, the isocyanate trimer is selected from hexamethylene diisocyanate trimer, isophorone diisocyanate trimer, or a mixture of the two; hexamethylene diisocyanate trimer has good weather resistance and is not easily affected by environmental factors such as light and temperature to cause yellowing or degradation. The coating or material formed after the hexamethylene diisocyanate trimer is cured usually has high hardness and adhesion, and exhibits good wear resistance and chemical resistance. These excellent physical properties enable the hexamethylene diisocyanate trimer to provide excellent strength and durability in recycled asphalt; isophorone diisocyanate trimer has excellent thermal stability, can maintain stable performance under high temperature conditions, is not prone to degradation or failure, and exhibits good reactivity and cross-linking properties during the cross-linking and curing reaction between isophorone diisocyanate trimer and isocyanate, which helps to form a tight and solid structure in the recycled asphalt and improve the overall strength and stability.

[0044] As one of the preferred embodiments of the present invention, in step S2, the mass ratio of hexamethylene diisocyanate trimer to cardanol is 1:(0.6~0.7); the mass ratio of isophorone diisocyanate trimer to cardanol is 1:(0.5~0.6); in the process of preparing the blocked isocyanate trimer, the addition amount of isocyanate trimer and cardanol needs to adopt a suitable addition ratio to ensure that the isocyanate trimer can react completely after the blocking reaction, avoid the blocked isocyanate trimer containing more unblocked isocyanate groups, thereby avoiding the curing phenomenon of the bonding material during storage or transportation at room temperature.

[0045] As one of the preferred embodiments of the present invention, in step S3, the mass ratio of the blocked isocyanate trimer to the epoxy component is 1:(1.5~2); the mixing ratio of the blocked isocyanate trimer and the epoxy component needs to be controlled within a reasonable range to ensure that the blocked isocyanate trimer can completely undergo cross-linking and curing reaction with the epoxy resin, thereby improving the utilization rate of the raw materials.

[0046] As one of the preferred embodiments of the present invention, in step S4, the heating temperature of the old asphalt material is 120 - 140 °C. Heating the old asphalt material can soften the asphaltene inside it, increase its fluidity, making it easier to be evenly mixed with the cementing material. Heating can also promote the regeneration of asphaltene in the old asphalt material, enabling it to restore or partially restore its original adhesion, flexibility and other properties. The recycled asphalt pavement includes the following components by mass percentage: 93% - 98% of old asphalt material, 2% - 7% of cementing material. A large amount of old asphalt material is added to the recycled asphalt pavement, improving the utilization rate of the old asphalt material and facilitating the recycling of resources.

[0047] In summary, the present invention uses a cementing material and old asphalt material as raw materials to produce recycled asphalt. The blocked isocyanate trimer is used as a cross-linking agent in the cementing material, enabling the cementing material to cross-link and cure at a relatively high temperature, thereby improving the convenience of the cementing material during daily storage and transportation. Moreover, it can enhance the bonding strength of the cementing material and the toughness after curing, which is beneficial to improving the mechanical strength of the recycled asphalt pavement. Additionally, the present invention does not require component analysis of the old asphalt material and has a high utilization rate of the old asphalt material, simplifying the regeneration operation of the old asphalt material and efficiently recycling the old asphalt pavement resources.

[0048] The present invention is further illustrated below through examples and comparative examples.

[0049] Example 1

[0050] S1. Put E20 epoxy resin and 70# petroleum asphalt into a stirring kettle, heat to 50 °C and stir evenly at the same time, then add C12 - 14 alkyl glycidyl ether and γ - glycidyl ether oxypropyltrimethoxysilane and stir evenly, and then cool to room temperature to obtain an epoxy component;

[0051] The epoxy component includes the following components by mass percentage: 80% of E20 epoxy resin, 105% of 70# petroleum asphalt, 9% of C12 - 14 alkyl glycidyl ether, 1% of γ - glycidyl ether oxypropyltrimethoxysilane;

[0052] S2. Add hexamethylene diisocyanate trimer into a reaction kettle, stir and heat to 75 °C. After the hexamethylene diisocyanate trimer is heated to a constant temperature, slowly drip cardanol into the reaction kettle through a dropping funnel. After the cardanol is added dropwise within 40 min, keep the temperature at 80 °C for reaction. After the heat preservation reaction for 1 h, detect the content of isocyanate groups in the product in the reaction kettle at regular intervals. When the mass percentage of isocyanate groups is less than 0.05%, it is determined that the hexamethylene diisocyanate trimer and cardanol in the reaction kettle have completely reacted. After the complete reaction of the hexamethylene diisocyanate trimer and cardanol in the reaction kettle, a blocked hexamethylene diisocyanate trimer is obtained;

[0053] In the reactor, the mass ratio of hexamethylene diisocyanate trimer to cashew phenol is 1:0.65;

[0054] S3. After the blocked hexamethylene diisocyanate trimer is cooled to room temperature, it is mixed with the epoxy component at a mass ratio of 1:1.75 to obtain a cementitious material;

[0055] S4. The old asphalt pavement materials are crushed and screened to obtain graded old asphalt materials. The graded old asphalt materials are stirred and heated to 135 °C, then the cementitious material is added. After continuous stirring and mixing evenly, the mixture is paved on the road surface and then leveled, compacted, and cured to form a recycled asphalt pavement;

[0056] The recycled asphalt pavement includes the following components by mass percentage: 98% of old asphalt materials and 2% of cementitious material.

[0057] Example 2

[0058] The difference between this example and Example 1 above is that in step S4, the recycled asphalt pavement includes the following components by mass percentage: 95.5% of old asphalt materials and 4.5% of cementitious material, and the rest of the operations and raw material components are the same.

[0059] Example 3

[0060] The difference between this example and Example 1 above is that in step S4, the recycled asphalt pavement includes the following components by mass percentage: 93% of old asphalt materials and 7% of cementitious material, and the rest of the operations and raw material components are the same.

[0061] Example 4

[0062] S1. Put E20 epoxy resin and 70# petroleum asphalt into a stirring kettle, heat to 50 °C and stir evenly at the same time, then put C12-14 alkyl glycidyl ether and γ-glycidoxypropyltrimethoxysilane and stir evenly, and then cool to room temperature to obtain an epoxy component;

[0063] The epoxy component includes the following components by mass percentage: 80% of E20 epoxy resin, 105% of 70# petroleum asphalt, 9% of C12-14 alkyl glycidyl ether, and 1% of γ-glycidoxypropyltrimethoxysilane;

[0064] S2. Add hexamethylene diisocyanate trimer into the reaction kettle, stir and heat it to 75°C. After the hexamethylene diisocyanate trimer is heated to a constant temperature, slowly drip cardanol into the reaction kettle through a dropping funnel. After the cardanol is added dropwise within 40 min, keep the temperature at 80°C for reaction. After the heat preservation reaction for 1 h, detect the content of isocyanate groups in the product in the reaction kettle at regular intervals. When the mass percentage of isocyanate groups is less than 0.05%, it is determined that the hexamethylene diisocyanate trimer and cardanol in the reaction kettle have completely reacted. After the complete reaction of the hexamethylene diisocyanate trimer and cardanol in the reaction kettle, a blocked hexamethylene diisocyanate trimer is obtained;

[0065] In the reaction kettle, the mass ratio of hexamethylene diisocyanate trimer to cardanol is 1:0.65;

[0066] S3. After the blocked hexamethylene diisocyanate trimer is cooled to room temperature, it is mixed with the epoxy component at a mass ratio of 1:1.75 to obtain a cementitious material;

[0067] S4. Heat the paraffin to melting, add iron powder and a special paraffin emulsifier, stir evenly, then add sodium chloride solution, inorganic salt stabilizer, and alcohol co-emulsifier, and emulsify them into an emulsion with sodium chloride solution wrapped by paraffin through common emulsification operations. While stirring the emulsion, gradually cool the emulsion, and the paraffin will gradually solidify to form granular oxygen-absorbing particles. The shell of the oxygen-absorbing particles is composed of paraffin and iron powder, and its interior is wrapped with sodium chloride solution;

[0068] Among them, the addition amounts of the special paraffin emulsifier, inorganic salt stabilizer, and alcohol co-emulsifier are added appropriately based on the current common paraffin emulsification process. The number of carbon atoms in the paraffin is 30. In the oxygen-absorbing particles, the mass ratio of paraffin, iron powder, and sodium chloride solution is 1:0.5:1.5, and the concentration of the sodium chloride solution is 2%;

[0069] S5. After the old asphalt pavement materials are crushed and screened, graded asphalt old materials are obtained. After the graded asphalt old materials are stirred and heated to 135°C, the cementitious material and oxygen-absorbing particles are added. After continuing to stir evenly, the mixture is paved on the road surface and then leveled, compacted, and cured to form a recycled asphalt pavement;

[0070] The recycled asphalt pavement includes the following components by mass percentage: asphalt old materials 94.5%, cementitious material 4.5%, and oxygen-absorbing particles 1%.

[0071] Comparative Example 1

[0072] Based on Example 6 in the specification of the general asphalt rejuvenator, its preparation and application (Publication No.: CN101845227A), a rejuvenated asphalt with a blending ratio of 30.6% of the rejuvenator was prepared. After paving this rejuvenated asphalt on the road surface and through leveling, compaction, and curing, a rejuvenated asphalt pavement was formed.

[0073] It should be noted that for the same gradation asphalt old materials in all the above examples and comparative examples, the mass percentages of asphalt old materials with sizes greater than 10 mm, 10 - 5 mm, 5 - 1 mm, and less than 1 mm added in the gradation asphalt old materials are 38%, 30%, 20%, and 12% respectively.

[0074] Based on the standard document "Reclaimed Asphalt Concrete" (GB / T 25033 - 2010), the void ratio, stability, flow value, dynamic stability, residual stability of the immersion Marshall test, residual strength ratio of the freeze - thaw splitting test, and failure strain index of the low - temperature bending test of the rejuvenated asphalt in all the above examples and comparative examples were detected. The test results are shown in Table 1 below.

[0075]

[0076] Table 1

[0077] From the data in Table 1, it can be seen that the performance indicators of Examples 1, 2, and 3 based on the technical solution of the present invention all meet the technical requirements of the rejuvenated asphalt. The performance indicators of Comparative Example 1 also meet the technical requirements of the rejuvenated asphalt. Some performance indicators in Comparative Example 1 are close to those in Example 1 or Example 2 or Example 3. It can be seen that the technical solutions of the present invention and Comparative Example 1 can both well recycle asphalt old materials and apply them to the rejuvenated asphalt pavement. However, it should be noted that 30.6% of the rejuvenator was added in Comparative Example 1, and its utilization rate of asphalt old materials is relatively low. Comparative Example 1 needs to consume more new raw materials to obtain a technical effect close to that of the technical solution of the present invention. The technical solution of the present invention can improve the utilization rate of asphalt old materials and reduce the production cost of the rejuvenated asphalt pavement.

[0078] Furthermore, in Example 4, oxygen-absorbing particles were added on the basis of Example 1. During the paving and gradual curing process of the recycled asphalt pavement, the high temperature would melt the paraffin shell of the oxygen-absorbing particles, enabling the iron powder to come into contact with the sodium chloride solution. The electrolyte environment provided by sodium chloride caused the iron powder, water, and oxygen to react in the high-temperature environment and generate iron hydroxide. This reaction occurred inside the recycled asphalt pavement, consuming the oxygen in the internal voids of the recycled asphalt pavement, creating a negative pressure inside the voids, enabling the recycled asphalt pavement to be better compacted and reducing the internal void ratio. Moreover, the deeper the voids in the recycled asphalt pavement, the lower the possibility of connection with the outside world, and the better the effect of forming a negative pressure in these voids. Therefore, the oxygen-absorbing particles can more efficiently reduce the void ratio deep in the recycled asphalt pavement. After the internal void ratio of the recycled asphalt pavement decreases, its technical indicators and mechanical properties will be better.

[0079] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A recycling process based on old asphalt pavement materials, characterized in that: The following steps are involved: S1. Adding epoxy resin and petroleum asphalt into a stirring kettle, heating and stirring evenly, then adding active diluent and accelerator, stirring evenly and cooling to room temperature to obtain epoxy component; S2, adding isocyanate trimer into a reactor and heating and stirring, after the isocyanate trimer is heated to a constant temperature, slowly dripping cardanol into the reactor through a dropping funnel, and after the dropwise addition of cardanol is completed, keeping the temperature to react, and the isocyanate trimer in the reactor completely reacts with cardanol to obtain a blocked isocyanate trimer; S3, after the blocked isocyanate trimer is cooled to room temperature, it is mixed with the epoxy component to obtain a bonding material; S4, heating the paraffin until it is melted, adding iron powder and a paraffin-specific emulsifier, and stirring evenly, then adding a sodium chloride solution, an inorganic salt stabilizer, and an alcohol emulsifier, and then emulsifying the sodium chloride solution wrapped in paraffin through a common emulsification operation, stirring the emulsion while gradually cooling the emulsion, the paraffin will gradually solidify to form granular oxygen-absorbing particles, the shell of the oxygen-absorbing particles is composed of paraffin and iron powder, and the interior is wrapped with a sodium chloride solution; S5. After crushing and screening the old asphalt pavement materials, the graded asphalt old materials are obtained. The graded asphalt old materials are stirred and heated to 135° C., and then a binder and oxygen-absorbing particles are added. After further stirring, the mixture is spread on the pavement, and then leveled, compacted, and solidified to form a regenerated asphalt pavement. Among them, the recycled asphalt pavement includes the following components by mass percentage: 94.5% old asphalt material, 4.5% binder, and 1% oxygen-absorbing particles.

2. The recycling process based on asphalt pavement waste materials according to claim 1 is characterized in that: The epoxy component includes the following components by mass percentage: 70% to 85% epoxy resin, 5% to 15% petroleum asphalt, 5% to 15% active diluent, and 0.5% to 1% accelerator.

3. The recycling process based on asphalt pavement waste materials according to claim 1 is characterized in that: During the process of the isocyanate trimer and cardanol reacting in the reactor while being kept warm, the content of isocyanate groups in the product in the reactor is detected at regular intervals. When the mass percentage of the isocyanate group is less than 0.05%, it is determined that the isocyanate trimer and cardanol in the reactor have completely reacted.

4. The recycling process based on asphalt pavement waste materials according to claim 1 is characterized in that: In step S2, the temperature at which the isocyanate trimer is heated in the reactor is 70-80° C., and the temperature at which the isocyanate trimer and cardanol are kept warm in the reactor for reaction is 70-90° C. for 1-4 hours.

5. The recycling process based on asphalt pavement waste materials according to claim 1 is characterized in that: The isocyanate trimer is selected from hexamethylene diisocyanate trimer and isophorone diisocyanate trimer, or a mixture of the two.

6. The recycling process based on asphalt pavement waste materials according to claim 5 is characterized in that: In step S2, the mass ratio of the hexamethylene diisocyanate trimer to cardanol is 1:(0.6-0.7).

7. The recycling process based on asphalt pavement waste materials according to claim 5 is characterized in that: In step S2, the mass ratio of the isophorone diisocyanate trimer to cardanol is 1:(0.5-0.6).

8. The recycling process based on asphalt pavement waste materials according to claim 1 is characterized in that: In step S3, the mass ratio of the blocked isocyanate trimer to the epoxy component is 1:(1.5-2).

9. The recycling process based on asphalt pavement waste materials according to claim 1 is characterized in that: In step S4, the heating temperature of the old asphalt material is 120-140°C.

10. The recycling process based on asphalt pavement waste materials according to claim 1 is characterized in that: The epoxy resin is selected from one or more of E20 epoxy resin, E44 epoxy resin, and E51 epoxy resin; The petroleum asphalt is selected from 70# petroleum asphalt, 90# petroleum asphalt, or a mixture of the two; The active diluent is selected from one or more of C12-14 alkyl glycidyl ether, butyl glycidyl ether, and benzyl glycidyl ether; The accelerator is γ-glycidyloxypropyltrimethoxysilane.

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