In-place warm recycled asphalt mixture and method of making same

Abstract

The present application relates to road engineering solid waste resource utilization, and in particular to a warm-in-place recycling asphalt mixture and a preparation method thereof.The warm-in-place recycling asphalt mixture uses a composite additive including a petroleum-based recycling agent and a surfactant warm-mixing agent.The warm-in-place recycling asphalt mixture includes the composite additive, waste asphalt mixture and new asphalt.The present application compounding the warm-mixing agent and the recycling agent to obtain a composite additive, which is directly mixed into the recycling agent in proportion during use, and then mixed with the old asphalt mixture to obtain the warm-in-place recycling asphalt mixture, which can reduce the construction temperature by more than 20 DEG C, reduce the construction energy consumption, reduce the environmental pollution and harmful gas emission, realize the performance improvement of the warm-in-place recycling asphalt mixture, promote the development of the warm-in-place recycling technology, and realize the recycling and utilization of the old asphalt pavement in the original level and in situ with high performance, high value and high efficiency.

Description

Technical Field

[0001] This invention relates to the resource utilization of solid waste from road engineering, specifically to on-site recycling technology for asphalt pavement and warm-mix asphalt mixture technology. Background Technology

[0002] In the current and foreseeable future period, the continued development of the economy and society will place new and greater demands on highway infrastructure construction, and highway transportation will remain in a long-term phase of large-scale construction and development. Simultaneously, with the further extension of the highway network, the periodic overhaul and maintenance tasks of operational highways are rapidly increasing, and the scale of major and medium-sized highway repairs will continue to operate at a high level. Major and medium-sized highway repairs generate a large amount of waste pavement materials; the amount of asphalt pavement waste generated annually on trunk highways alone exceeds 200 million tons, posing a significant challenge to sustainable development.

[0003] In-situ thermal recycling technology is a continuous on-site thermal recycling operation method with the characteristics of economy, efficiency, speed, environmental protection and saving. In-situ thermal recycling technology can make the most of the original road surface materials and is a very valuable road recycling technology. It can quickly repair the original road surface defects and has significant economic and environmental benefits. At the same time, the construction process does not require closing traffic and does not increase the pressure on highway traffic. However, the traditional in-situ thermal recycling technology has a high heating temperature of the original road surface during the construction process, which consumes a lot of energy, causes serious smoke pollution, and causes serious aging of asphalt mixture. The large-scale application is greatly limited, which seriously restricts the efficient recycling of asphalt pavement. The main technical bottlenecks are as follows: (1) The traditional in-situ thermal recycling road surface heating temperature is higher than 200℃. The asphalt on the surface of the old material is easy to carbonize and lose its bonding effect. The asphalt recycling activation rate is low, and improving the performance of recycled materials has become a key problem; (2) The traditional in-situ thermal recycling consumes a lot of energy and emits strong carcinogens such as asphalt smoke and benzo[a]pyrene. Reducing environmental pollution has become a key problem.

[0004] Warm mix asphalt technology is a green paving technology that reduces energy consumption and emissions of greenhouse gases and harmful substances by lowering the construction temperature. It also improves on-site compaction and is gaining increasing attention, with its application already reaching a considerable scale. Applying warm mix technology to in-situ thermal recycling can significantly reduce the surface heating temperature, prevent surface asphalt carbonization, and achieve efficient and clean in-situ recycling of asphalt pavements. However, existing warm mix asphalt technologies are developed for factory production. When used for in-situ recycling, the lack of storage devices for warm mix additives in in-situ thermal recycling equipment makes it difficult to simultaneously add warm mix additives and recycling agents. Summary of the Invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems.

[0006] The application provides a warm-in-place recycled asphalt mixture and a preparation method thereof.

[0007] The application first provides a composite additive for the warm-in-place recycled asphalt mixture, which comprises a petroleum-based recycling agent and a surfactant warm-mixing agent.

[0008] According to the embodiment of the application, the main component of the petroleum-based recycling agent is polycyclic aromatic hydrocarbon extraction oil.

[0009] According to the embodiment of the application, the surfactant warm-mixing agent is an organic modified siloxane-based warm-mixing agent.

[0010] According to the embodiment of the application, the mass ratio of the petroleum-based recycling agent to the surfactant warm-mixing agent in the composite additive for the warm-in-place recycled asphalt mixture is (25-90):1, for example, 46.5:1.

[0011] According to the embodiment of the application, the composite additive for the warm-in-place recycled asphalt mixture is composed of the petroleum-based recycling agent and the surfactant warm-mixing agent.

[0012] The application adopts the compounding of the petroleum-based recycling agent (the main component is polycyclic aromatic hydrocarbon extraction oil) and the surfactant warm-mixing agent (the organic modified siloxane-based warm-mixing agent) to obtain a new type of additive with the functions of warm-mixing and recycling, and to improve the water resistance of the mixture, so as to reduce the construction temperature of the warm-in-place recycled asphalt mixture.

[0013] The application also provides the application of the composite additive in the warm-in-place recycled asphalt mixture.

[0014] The application also provides a warm-in-place recycled asphalt mixture comprising the composite additive.

[0015] According to the embodiment of the application, the warm-in-place recycled asphalt mixture further comprises waste asphalt mixture (RAP).

[0016] According to an embodiment of the present invention, the asphalt content in the waste asphalt mixture (RAP) is 3.5-5.5%, for example, 4%.

[0017] According to an embodiment of the present invention, the in-situ temperature recycled asphalt mixture further includes new asphalt mixture.

[0018] According to an embodiment of the present invention, in the in-situ temperature recycled asphalt mixture, the mass ratio of waste asphalt mixture (RAP) to new asphalt mixture is (8-10):1, and optionally 9:1.

[0019] According to an embodiment of the present invention, by controlling the amount of petroleum-based regenerator added, the penetration (25°C) / 0.1mm of the recycled asphalt in the in-situ recycled asphalt mixture is made to be 40-70, for example 49.9.

[0020] According to an embodiment of the present invention, in the in-situ recycled asphalt mixture, the content of the petroleum-based recycler is 3-12% of the asphalt content in the waste asphalt mixture (RAP), for example, 6%.

[0021] According to an embodiment of the present invention, the in-situ temperature-recycled asphalt mixture includes the above-mentioned composite additive, waste asphalt mixture (RAP), and new asphalt mixture; wherein, the mass ratio of waste asphalt mixture (RAP) to new asphalt mixture is 9:1; the content of the petroleum-based recycler is 6% of the asphalt content in the waste asphalt mixture (RAP); and the mass ratio of petroleum-based recycler to surfactant-type warm mix agent is 46.5:1.

[0022] The present invention also provides a method for preparing the above-mentioned in-situ temperature recycled asphalt mixture, comprising: mixing the above-mentioned composite additive, waste asphalt mixture (RAP) and new asphalt mixture according to the proportion.

[0023] Major and medium-scale road maintenance and repairs generate a large amount of waste asphalt pavement materials, posing a significant challenge to sustainable development. In-situ thermal recycling technology for asphalt pavement can maximize the use of existing pavement materials, effectively addressing the environmental problems associated with waste. However, traditional in-situ thermal recycling technologies involve heating the original pavement at high temperatures during construction, resulting in high energy consumption, severe flue gas pollution, and significant aging of the asphalt mixture. Warm-mix asphalt technology can effectively reduce the construction temperature of asphalt mixtures. This invention combines a warm-mix agent with a recycling agent to obtain a composite additive. During use, this additive is directly mixed into the recycling agent according to a specified ratio, and then mixed with the old asphalt mixture to obtain in-situ warm-mix recycled asphalt mixture. This can reduce the construction temperature by more than 20°C, lower construction energy consumption, reduce environmental pollution and harmful gas emissions, improve the road performance of in-situ recycled asphalt mixtures, promote the development of in-situ thermal recycling technology, and achieve "high-performance, high-value, and high-efficiency" in-situ recycling of old asphalt pavements. Attached Figure Description

[0024] Figure 1 Fluorescence microscope image of the petroleum-based rejuvenator (RA-5).

[0025] Figure 2 Fluorescence microscope image of the petroleum-based rejuvenator (RA-5) mixed with the surfactant warm-mixing agent (Sinochem TEGO XP32157).

[0026] Figure 3 Fluorescence microscope image of the amine surfactant warm-mixing agent compounded with the petroleum-based rejuvenator (RA-5). DETAILED DESCRIPTION

[0027] The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application.

[0028] The following petroleum-based rejuvenator is a rejuvenator that meets the technical requirements of RA-5 in the Technical Specification for Highway Asphalt Pavement Recycling (JTG / T 5521-2019). The following surfactant warm-mixing agent is Sinochem TEGO XP32157.

[0029] First, the amount of the rejuvenator is determined according to the penetration of the recovered asphalt in the waste asphalt mixture (RAP); second, the warm-mixing agent is mixed into the rejuvenator according to the recommended amount of the warm-mixing agent, and simple stirring is performed to form a new additive; finally, the new additive is added to the waste asphalt mixture for in-place hot recycling mixing to generate in-place warm-recycled asphalt mixture, thereby reducing the construction temperature of the in-place hot-recycled asphalt mixture, improving the road performance of the in-place hot-recycled asphalt mixture, reducing construction energy consumption, and reducing environmental pollution and harmful gas emissions.

[0030] In order to solve the production problem of the in-place warm-mixing recycled asphalt mixture, the present application provides a preparation method of a new additive suitable for in-place hot recycling, which comprises the following steps:

[0031] 1. The waste asphalt mixture (RAP) is extracted and sieved, and the recovered asphalt is tested for penetration, softening point, and ductility.

[0032] 2. According to the test value of the recovered asphalt penetration, the recommended amount of the petroleum-based rejuvenator is selected, the recovered asphalt penetration is restored to the specification requirement, and the optimal amount of the rejuvenator is determined.

[0033] 3. The mixture ratio design of the recycled asphalt mixture is performed according to the specification, and the asphalt amount of the recycled asphalt mixture is determined.

[0034] 4. According to the asphalt amount of the recycled asphalt mixture, the amount of the warm-mixing agent is calculated, and the amount of the warm-mixing agent is 0.1% (mass ratio) of the asphalt amount.

[0035] 5. When mixing the warm-in-place recycled asphalt mixture, the amount of the recycling agent is determined according to the amount of the recycled asphalt, the calculated amount of the warm-mixing agent is added to the recycling agent, and stirring is performed for 30 min, so that the new composite additive having the functions of warm mixing and recycling is prepared.

[0036] 6. When mixing the subsequent warm-in-place recycled asphalt mixture, the composite additive is added according to the adding procedure of the recycling agent.

[0037] Example 1

[0038] 1. 100 kg of waste asphalt mixture (RAP) is extracted and sieved, and the recycled asphalt is tested for penetration, softening point and ductility. The test values are shown in Table 1.

[0039] 2. According to the test value of the penetration of the recycled asphalt, the recommended amount of the petroleum-based recycling agent is selected, the amount of the recycling agent added to the recycled asphalt is determined by trial, the test results are shown in Table 1, the penetration of the recycled asphalt is reduced to the required value in the specification, and the optimal amount of the recycling agent is determined to be 6%.

[0040] Table 1 Test results of the recycled asphalt in RAP and the recycling agent

[0041]

[0042] 3. According to the extraction and sieving results of RAP, the asphalt content in RAP is 4.0%, the AC-13 gradation is selected, the mixture ratio design of the recycled asphalt mixture is performed according to the specification, the molding temperature of the mixture is 145°C, the air void content is 4.1%, and the asphalt content of the recycled asphalt mixture is determined to be 4.67%.

[0043] 4. According to the asphalt content of the recycled asphalt mixture, the amount of the warm-mixing agent is calculated, and the amount of the warm-mixing agent is 0.1% (mass ratio) of the asphalt content.

[0044] 5. 6000 g of the warm-in-place recycled asphalt mixture is mixed, in which the mass of RAP is 5400 g, and the mass of the new asphalt mixture is 600 g. The asphalt content in RAP is 4.0%, and the mass of the recycled asphalt is 216 g. The amount of the recycling agent is 6% of the recycled asphalt according to the second step, i.e. 12.96 g.

[0045] 6. According to the results of the third step, the asphalt content of the recycled asphalt mixture is 4.67%, and the mass is 280.2 g. The mass of the warm-mixing agent is calculated to be 0.28 g.

[0046] 7. 0.28 g of the warm-mixing agent is added to 12.96 g of the recycling agent, and stirring is performed for 30 min, so that the composite additive is prepared.

[0047] 8. When mixing the subsequent warm-in-place recycled asphalt mixture, the composite additive is added according to the adding procedure of the recycling agent.

[0048] 9. After determining the optimum asphalt-aggregate ratio of hot in-place recycled asphalt mixture, the molding temperature of warm mix asphalt mixture is determined by the "equal air void method" of hot mix asphalt mixture. The mixing temperature of warm in-place recycled asphalt mixture is selected as 135℃, 130℃ and 125℃ according to experience, and finally determined as 130℃.

[0049] 10. The warm in-place recycled asphalt mixture is prepared and its road performance indexes are tested, as shown in Table 2.

[0050] Table 2 Test results of road performance of two kinds of asphalt mixtures

[0051]

[0052] As can be seen from the test results in Table 2, the warm in-place recycled asphalt mixture prepared by the application has the same performance as the hot in-place recycled asphalt mixture, the freeze-thaw splitting strength ratio is obviously improved, and both meet the specification requirements, while the mixing temperature is reduced by 15℃ in the laboratory. Since the compaction work of field compaction equipment is much larger than the compaction work in the laboratory, according to field construction experience, the construction temperature can be reduced by more than 20℃ in the field. The construction energy consumption can be effectively reduced, and the environmental pollution and harmful gas emissions can be reduced.

[0053] The application proposes a compounding technology of petroleum-based recycling agent (main component is polycyclic aromatic hydrocarbon extraction oil) and surfactant-based warm mix agent (warm mix agent based on organic modified siloxane), the compounding material and operation method are simple, no additional materials are needed, the warm mix agent based on organic modified siloxane has good compatibility with the petroleum-based recycling agent, and the compound additive with warm mix and recycling functions can be prepared by simple stirring.

[0054] After the application is adopted, the mixing temperature of hot in-place recycled asphalt mixture can be reduced by more than 20℃, the aging of asphalt in the mixing process is reduced, the road performance of hot in-place recycled asphalt mixture is improved, the construction energy consumption is reduced, the environmental pollution and harmful gas emissions are reduced, and the development of hot in-place recycling technology is promoted.

[0055] Experimental example

[0056] The petroleum-based recycling agent (RA-5) used in Example 1 is observed by a fluorescence microscope, as shown in Figure 1 . After the petroleum-based recycling agent (RA-5) is uniformly mixed with the surfactant-based warm mix agent (Sinochem TEGO XP32157), the mixture is observed by a fluorescence microscope, as shown in Figure 2 . It can be seen that there is no obvious impurity after mixing, and there is no difference from the original petroleum-based recycling agent (RA-5).

[0057] During the research, the inventors tried to mix another amine surfactant warm-mixing agent with the petroleum-based rejuvenator (RA-5). The two liquids were mixed in a container in equal proportions and stirred for 30 minutes. After standing for ten minutes, it was found that the amine warm-mixing agent floated on the surface of the rejuvenator. Subsequent observation using a fluorescence microscope showed that Figure 3 there was a clear boundary between the warm-mixing agent and the rejuvenator. If the rejuvenator and the warm-mixing agent cannot be uniformly mixed, the warm-mixing agent, which is generally lighter in quality, will float on the surface of the rejuvenator, and when used, will not be sprayed uniformly and will not be able to fully play its warm-mixing role.

[0058] Although the present application has been described in detail with general description and specific embodiments above, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of the present application claimed.

Claims

1. A composite additive for warm in-place recycled asphalt mixture, characterized by, The compound additive for in-situ warm recycling asphalt mixture comprises: a petroleum-based recycling agent, and a surfactant warm mixing agent, wherein the petroleum-based recycling agent is mainly composed of polycyclic aromatic hydrocarbon extract oil; the surfactant warm mixing agent is TEGO XP32157 from Evonik; in the compound additive for in-situ warm recycling asphalt mixture, the mass ratio of the petroleum-based recycling agent to the surfactant warm mixing agent is (25-90):

1.

2. The composite additive for warm in-place recycling of asphalt mixtures according to claim 1, characterized in that, the petroleum-based recycling agent is selected from recycling agents satisfying the technical requirements of RA-1, RA-5 and RA-25 in the Technical Specification for Recycling of Highway Asphalt Pavement (JTG / T 5521-2019).

3. The composite additive for warm in-place recycling of asphalt mixtures according to claim 1, characterized in that, in the compound additive for in-situ warm recycling asphalt mixture, the mass ratio of the petroleum-based recycling agent to the surfactant warm mixing agent is 46.5:

1.

4. The compound additive according to any one of claims 1-3 is used in in-situ warm recycling asphalt mixture.

5. A hot-in-place recycled asphalt mixture characterized in that, The compound additive according to any one of claims 1-3 is included.

6. The warm in-place recycled asphalt mixture of claim 5, wherein, The in-situ warm recycling asphalt mixture further comprises waste asphalt mixture.

7. The warm in-place recycled asphalt mixture of claim 6, wherein, The asphalt content in the waste asphalt mixture is 3.5-5.5%.

8. The warm in-place recycled asphalt mixture of claim 6, wherein, The asphalt content in the waste asphalt mixture is 4%.

9. The warm in-place recycled asphalt mixture of claim 8, wherein, The in-situ warm recycling asphalt mixture further comprises new asphalt mixture.

10. The warm in-place recycled asphalt mixture of claim 9, wherein, In the in-situ warm recycling asphalt mixture, the mass ratio of the waste asphalt mixture (RAP) to the new asphalt mixture is (8-10):

1.

11. The warm in-place recycled asphalt mixture of claim 10, wherein, In the in-situ warm recycling asphalt mixture, the mass ratio of the waste asphalt mixture (RAP) to the new asphalt mixture is 9:

1.

12. The warm in-place recycled asphalt mixture of claim 11, wherein, The penetration of the recycled asphalt in the in-situ warm recycling asphalt mixture is 40-70 at 25℃ / 0.1mm by controlling the addition amount of the petroleum-based recycling agent. Alternatively, the content of the petroleum-based recycling agent in the in-situ warm recycling asphalt mixture is 3-12% of the asphalt content in the waste asphalt mixture.

13. The warm in-place recycled asphalt mixture of claim 12, wherein, The penetration of the recycled asphalt in the in-situ warm recycling asphalt mixture is 49.9 at 25℃ / 0.1mm by controlling the addition amount of the petroleum-based recycling agent. Alternatively, the content of the petroleum-based recycling agent in the in-situ warm recycling asphalt mixture is 6% of the asphalt content in the waste asphalt mixture.

14. The warm in-place recycled asphalt mixture of claim 13, wherein, The in-situ warm recycling asphalt mixture comprises the compound additive, the waste asphalt mixture and the new asphalt mixture; the mass ratio of the waste asphalt mixture to the new asphalt mixture is 9:1; the content of the petroleum-based recycling agent is 6% of the asphalt content in the waste asphalt mixture; and the mass ratio of the petroleum-based recycling agent to the surfactant warm mixing agent is 46.5:

1.

15. The method of producing a warm in-place recycled asphalt mixture according to any one of claims 5 to 14, characterized in that, The compound additive for in-situ warm recycling asphalt mixture comprises: The compound additive, the waste asphalt mixture and the new asphalt mixture are mixed according to the mixing ratio.

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