High-strength and high-toughness hot in-place recycling asphalt mixture as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a high-strength and high-toughness hot in-place recycling asphalt mixture, which comprises the following steps: A, detecting an asphalt recycled material to obtain a detection result; b, according to the detection result, the gradation of the hot in-place recycling asphalt mixture and the gradation of the mineral aggregate, determining the use amounts of the high-viscosity and high-elasticity modified asphalt, the asphalt recycled material and the new mineral aggregate; c, respectively preheating the high-viscosity and high-elasticity modified asphalt, the asphalt reclaimed material and the new mineral aggregate; d, mixing the new mineral aggregate with a part of high-viscosity and high-elasticity modified asphalt to obtain an oil-rich large-particle-size asphalt mixture; and E, mixing the asphalt recycled material, sequentially adding the oil-rich large-particle-size asphalt mixture and the residual amount of high-viscosity and high-elasticity modified asphalt, and mixing to obtain the high-strength and high-toughness hot in-place recycling asphalt mixture. The preparation method of the high-strength and high-toughness hot in-place recycling asphalt mixture provided by the invention effectively solves the technical problems of poor pavement performance and durability of a recycled asphalt pavement prepared from the hot in-place recycling asphalt mixture in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering construction, and in particular to a high-strength and high-toughness in-situ hot-regenerated asphalt mixture and a preparation method thereof. Background Art

[0002] In the field of traditional road engineering, the recycling of asphalt waste is an important challenge that needs to be solved urgently. With the acceleration of industrialization and the advancement of urbanization, the demand for road construction and maintenance is increasing, and the amount of asphalt waste (i.e. recycled asphalt) is also increasing. If the above-mentioned recycled asphalt is not properly handled and effectively utilized, it will not only cause a huge waste of resources, but also may cause serious pollution to the environment.

[0003] In order to alleviate the above-mentioned problems of resource waste and environmental pollution, the traditional process usually mixes the recycled asphalt with new asphalt and new mineral materials at the construction site to obtain in-situ cold recycled asphalt mixture. Although in-situ cold recycled asphalt mixture is more in line with the green and low-carbon standards, it is limited by the selection of materials, slow construction speed, low application layer and imperfect test guidance specifications, which has limited the promotion and application of in-situ cold recycled asphalt mixture.

[0004] Compared with on-site cold recycled asphalt mixture, the relevant technology of on-site hot recycled asphalt mixture is more mature. The asphalt paved with on-site hot recycled asphalt mixture can not only be used as the surface layer of high-grade roads (such as expressways or first-class highways), but also can effectively repair road surface diseases and improve road service levels, realizing the high-value recovery and utilization of recycled asphalt materials, and making on-site hot recycled asphalt mixture more conducive to promotion and application.

[0005] However, the existing hot-regenerated asphalt mixture has the following defects: (1) The current hot-regenerated technology standard is low, the adopted asphalt technical indicators and design methods are backward, and there are generally problems such as poor durability and rapid attenuation of road performance, which makes it difficult to meet the use requirements of places with high requirements for road performance and durability of regenerated asphalt pavement; (2) In the preparation process of hot-regenerated asphalt mixture, all raw materials such as asphalt recycling material, new mineral material and new asphalt are usually mixed together, which makes it difficult for the new mineral material to be evenly coated by the new asphalt and partially exposed, thereby greatly affecting the toughness and strength of the hot-regenerated asphalt mixture obtained, and also affecting the road performance and durability of the regenerated asphalt pavement. That is, the strength and toughness of the hot-regenerated asphalt mixture in the prior art are both poor, resulting in poor road performance and durability of the regenerated asphalt pavement, which makes it difficult to meet the use requirements of places with high requirements for road performance and durability of the regenerated asphalt pavement. Summary of the invention

[0006] One of the purposes of the present invention is to propose a method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture. The preparation method is simple and easy to operate. On the premise of increasing the dosage of recycled asphalt materials and reducing production costs, its strength and toughness are ensured, and the technical problem of poor road performance and durability of existing regenerated asphalt pavements made using in-situ hot-regenerated asphalt mixtures is effectively solved.

[0007] The second purpose of the present invention is to provide a high-strength and high-toughness in-situ hot-regenerated asphalt mixture, which has high strength and toughness, and is conducive to ensuring the road performance and durability of the regenerated asphalt pavement.

[0008] The third object of the present invention is to provide an application of a high-strength and high-toughness in-situ hot-regenerated asphalt mixture, which is used in paving regenerated asphalt pavement to ensure the road performance and durability of the resulting regenerated asphalt pavement.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] A method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture comprises the following steps:

[0011] A. Detect the old asphalt content, old asphalt properties and old mineral material gradation in the asphalt recycling material to obtain the test results;

[0012] B. Determine the amount of high-viscosity and high-elastic modified asphalt, asphalt recycling material and new mineral material according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared;

[0013] Wherein, calculated by weight, the new mineral material comprises 50-60 parts of a first coarse aggregate of 10-15 mm, 25-35 parts of a second coarse aggregate of 5-10 mm and 6-8 parts of mineral powder; the 60°C composite shear modulus G* of the high-viscosity and high-elasticity modified asphalt is ≥10KPa, the 60°C dynamic viscosity is ≥400,000 Pa·s, and the 25°C elastic recovery is >95%;

[0014] C. Preheat the high-viscosity and high-elasticity modified asphalt, asphalt recycling material and new mineral material respectively;

[0015] D. Add the new mineral material and a part of the high-viscosity and high-elasticity modified asphalt into the preheated first mixing equipment according to the amount determined in step B, and mix them to obtain an oil-rich and large-particle asphalt mixture;

[0016] E. Add the asphalt recovery material into the preheated second mixing equipment according to the amount determined in step B, and then add the oil-rich large-particle asphalt mixture and the remaining amount of high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture;

[0017] The high-strength and high-toughness in-situ hot-regenerated asphalt mixture is a skeleton-dense asphalt mixture, and calculated by mass percentage, the amount of recycled asphalt in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is greater than 60%.

[0018] Furthermore, in step B, the grading of mineral materials in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is as follows: the pass rate of 16 mm sieve hole is 100%, the pass rate of 13.2 mm sieve hole is 90-100%, the pass rate of 9.5 mm sieve hole is 50-75%, the pass rate of 4.75 mm sieve hole is 20-34%, the pass rate of 2.36 mm sieve hole is 15-26%, the pass rate of 1.18 mm sieve hole is 14-24%, the pass rate of 0.6 mm sieve hole is 12-20%, the pass rate of 0.3 mm sieve hole is 10-16%, the pass rate of 0.15 mm sieve hole is 9-15% and the pass rate of 0.075 mm sieve hole is 8-12%.

[0019] Furthermore, in step B, the high-viscosity and high-elasticity modified asphalt includes an SBS modifier, and calculated by mass percentage, the added amount of the SBS modifier is ≥10%.

[0020] Furthermore, in step B, the first coarse aggregate and the second coarse aggregate are any one of diabase, basalt and diorite.

[0021] Furthermore, in step B, the mineral powder is limestone, and the apparent relative density of the mineral powder is greater than 2.50 g / cm 3 , the hydrophilic coefficient is less than 1, and the water content of the mineral powder is less than 1% calculated by mass percentage.

[0022] Further, steps B, C, D and E are specifically as follows:

[0023] B. Determine the amount of high-viscosity and high-elastic modified asphalt, asphalt recycling material, new mineral material and regeneration agent according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared, and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared;

[0024] C. Preheat the high-viscosity and high-elasticity modified asphalt, asphalt recycling material, new mineral material and regeneration agent respectively;

[0025] D. Add the new mineral material and a part of the high-viscosity and high-elasticity modified asphalt into the preheated first mixing equipment according to the amount determined in step B, and mix them to obtain an oil-rich and large-particle asphalt mixture;

[0026] E. Add the asphalt recovery material into the preheated second mixing equipment according to the amount determined in step B, and then add the regeneration agent, oil-rich large-particle asphalt mixture and the remaining amount of high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture.

[0027] Furthermore, in step B, calculated by mass percentage, the high-strength and high-toughness in-situ hot-regenerated asphalt mixture includes 1.0-5.0% of high-viscosity and high-elasticity modified asphalt, 65-80% of asphalt recycling material, 15-28% of new mineral material and 0.04-0.16% of regeneration agent.

[0028] Furthermore, in step D, calculated by mass ratio, the mixing ratio of the new mineral material to the high-viscosity and high-elasticity modified asphalt in the oil-rich large-particle asphalt mixture is (10-13):1.

[0029] A high-strength and high-toughness in-situ hot-regenerated asphalt mixture is prepared using the above-mentioned method for preparing the high-strength and high-toughness in-situ hot-regenerated asphalt mixture.

[0030] A high-strength and high-toughness hot-regenerated asphalt mixture is used in a regenerated asphalt pavement, using the high-strength and high-toughness hot-regenerated asphalt mixture mentioned above, and the paving thickness of the ultra-high-strength and high-toughness hot-regenerated asphalt mixture is 4 to 5 cm.

[0031] The technical solution provided by the present invention may include the following beneficial effects:

[0032] 1. In the present technical solution, the hot-regenerated asphalt mixture in situ is preferably a skeleton-dense asphalt mixture. The skeleton structure of the asphalt mixture is formed by coarse aggregate, and the gaps between the coarse aggregate are fully filled to form a higher density, so that it has high strength, high toughness and high stability, thereby ensuring the road performance and durability of the hot-regenerated asphalt mixture in situ.

[0033] 2. In order to make the hot-regenerated asphalt mixture in situ a skeleton-dense asphalt mixture, the aggregate combination in the new mineral material in this technical solution is specifically limited to a first coarse aggregate of 10 to 15 mm and a second coarse aggregate of 5 to 10 mm, which is conducive to making the hot-regenerated asphalt mixture in situ a skeleton-dense asphalt mixture, thereby ensuring the strength and toughness of the hot-regenerated asphalt mixture in situ, and ensuring road performance and durability.

[0034] 3. In the technical scheme, the new mineral powder and a part of the high-viscosity and high-elasticity modified asphalt (i.e., new asphalt) are first mixed to obtain an oil-rich large-particle asphalt mixture, and then the oil-rich large-particle asphalt mixture is mixed with recycled asphalt and the remaining amount of new asphalt, thereby avoiding the direct use of new mineral materials, recycled asphalt materials and new asphalt. The new mineral materials are not easily coated evenly and are partially exposed, which in turn affects the performance of the in-situ hot-regenerated asphalt mixture. This is beneficial to ensuring the performance of the in-situ hot-regenerated asphalt mixture.

[0035] 4. In this technical solution, high-viscosity and high-elasticity modified asphalt is used to wrap the recycled asphalt material and coarse aggregate, and the type of high-strength and high-toughness in-situ hot-regenerated asphalt mixture is limited to a skeleton-dense asphalt mixture. When the amount of recycled asphalt material is higher than 60%, the asphalt mixture can still have high strength and high toughness, thereby ensuring the road performance of the recycled asphalt pavement. DETAILED DESCRIPTION

[0036] The present technical solution provides a method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture, comprising the following steps:

[0037] A. Detect the old asphalt content, old asphalt properties and old mineral material gradation in the asphalt recycling material to obtain the test results;

[0038] B. Determine the amount of high-viscosity and high-elastic modified asphalt, asphalt recycling material and new mineral material according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared;

[0039] Wherein, calculated by weight, the new mineral material comprises 50-60 parts of a first coarse aggregate of 10-15 mm, 25-35 parts of a second coarse aggregate of 5-10 mm and 6-8 parts of mineral powder; the 60°C composite shear modulus G* of the high-viscosity and high-elasticity modified asphalt is ≥10KPa, the 60°C dynamic viscosity is ≥400,000 Pa·s, and the 25°C elastic recovery is >95%;

[0040] C. Preheat the high-viscosity and high-elasticity modified asphalt, asphalt recycling material and new mineral material respectively;

[0041] D. Add the new mineral material and a part of the high-viscosity and high-elasticity modified asphalt into the preheated first mixing equipment according to the amount determined in step B, and mix them to obtain an oil-rich and large-particle asphalt mixture;

[0042] E. Add the asphalt recovery material into the preheated second mixing equipment according to the amount determined in step B, and then add the oil-rich large-particle asphalt mixture and the remaining amount of high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture;

[0043] The high-strength and high-toughness in-situ hot-regenerated asphalt mixture is a skeleton-dense asphalt mixture, and calculated by mass percentage, the amount of recycled asphalt in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is greater than 60%.

[0044] In order to solve the technical problem in the prior art that the strength and toughness of the in-situ hot-regenerated asphalt mixture are poor, resulting in poor road performance and durability of the regenerated asphalt pavement, the present technical solution proposes a method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture, by designing the type, preparation method and raw materials of the in-situ hot-regenerated asphalt mixture, while increasing the dosage of recycled asphalt and reducing production costs, the in-situ hot-regenerated asphalt mixture has excellent strength and toughness, ensuring that the regenerated asphalt pavement paved therefrom has good road performance and durability such as resistance to rutting, cracking, water damage and fatigue, and meets actual use needs.

[0045] Specifically, in-situ hot-regenerated asphalt mixtures in the prior art mainly include suspended dense asphalt mixtures and skeleton void asphalt mixtures. Among them, the suspended dense asphalt mixture is a dense mixture composed of mineral materials (including old mineral materials in asphalt recycling materials and newly added new mineral materials) and asphalt that present a continuous gradation as a whole. In the above-mentioned asphalt mixture, since the amount of coarse aggregate is small and the amount of fine aggregate is large, the coarse aggregate is squeezed apart by the fine aggregate, so that the coarse aggregate exists in the fine aggregate in a suspended state, resulting in the suspended dense asphalt mixture being easy to soften at high temperature and the stability is reduced, and it is easy to harden at low temperature and the brittleness increases. That is, the strength and toughness of the suspended dense asphalt mixture are reduced, so that the road performance and durability of the regenerated asphalt pavement paved with it are poor.

[0046] In addition, the skeleton void type asphalt mixture is a mixture with voids composed of mineral aggregates (including old mineral aggregates in asphalt recycling materials and newly added new mineral aggregates) and asphalt that present a continuous open gradation as a whole. In the above asphalt mixture, there are more coarse aggregates, which are closely connected to each other to form a skeleton, while the amount of fine aggregates is small and insufficient to fully fill the voids, which also reduces the strength and toughness of the skeleton void type asphalt mixture, resulting in poor road performance and durability of the recycled asphalt pavement paved with it, which is difficult to meet the actual use requirements.

[0047] In order to make the hot-regenerated asphalt mixture in situ have higher strength and toughness, the hot-regenerated asphalt mixture in situ is specially selected as a skeleton-dense asphalt mixture in the present technical solution. The skeleton structure of the asphalt mixture is formed by coarse aggregate, and the gaps between the coarse aggregate are fully filled to form a higher density, so that it has high strength, high toughness and high stability, thereby ensuring the road performance and durability of the hot-regenerated asphalt mixture in situ.

[0048] More specifically, since recycled asphalt materials generally need to be obtained by milling regenerated asphalt pavement, the original coarse aggregate in the recycled asphalt materials is broken into fine aggregate during the milling process, making the old aggregate in the recycled asphalt materials mainly fine aggregate. If the newly added coarse aggregate in the on-site hot-regenerated asphalt mixture is insufficient, the obtained on-site hot-regenerated asphalt mixture will be a suspended dense asphalt mixture or a skeleton void asphalt mixture, which cannot meet the use requirements.

[0049] In order to make the hot-regenerated in-situ asphalt mixture a skeleton-dense asphalt mixture, the aggregate combination in the new mineral material is specifically limited to a first coarse aggregate of 10 to 15 mm and a second coarse aggregate of 5 to 10 mm in this technical solution, which is conducive to making the hot-regenerated in-situ asphalt mixture a skeleton-dense asphalt mixture, thereby ensuring the strength and toughness of the hot-regenerated in-situ asphalt mixture, and guaranteeing road performance and durability.

[0050] Secondly, in the prior art, in the preparation process of hot-recycled asphalt mixture in situ, all raw materials such as recycled asphalt, new mineral materials and new asphalt are usually mixed together, which makes it difficult for the new mineral materials to be evenly coated by the new asphalt and causes partial exposure, affecting the toughness and strength of the hot-recycled asphalt mixture in situ, and further affecting the road performance and durability of the recycled asphalt pavement.

[0051] In order to further improve the toughness and strength of the in-situ hot-recycled asphalt mixture, in this technical scheme, new mineral materials and a partial amount of high-viscosity and high-elasticity modified asphalt (i.e., new asphalt) are first mixed to obtain an oil-rich large-particle asphalt mixture, and then the oil-rich large-particle asphalt mixture is mixed with recycled asphalt and the remaining amount of new asphalt, thereby avoiding the direct use of new mineral materials, recycled asphalt and new asphalt. The new mineral materials are not easily evenly coated and partially exposed, which in turn affects the performance of the in-situ hot-recycled asphalt mixture. This is beneficial to ensuring the performance of the in-situ hot-recycled asphalt mixture.

[0052] Thirdly, since the new aggregate composed of the first coarse aggregate of 10-15 mm and the second coarse aggregate of 5-10 mm is coarse aggregate, the specific surface area is small, resulting in limited contact area with the new asphalt. When ordinary modified asphalt is used, it is easy to have insufficient adhesion to the new aggregate. In addition, since the asphalt recycling material is an aged asphalt mixture that has been used many times, the oil content in the asphalt recycling material is reduced, while the colloid and asphaltene content are increased, which reduces the viscosity of the asphalt recycling material, and the low-temperature crack resistance and toughness are both deteriorated. When ordinary modified asphalt is used, it is also easy to have insufficient adhesion to the asphalt recycling material. Therefore, this technical solution especially uses highly viscous and highly elastic modified asphalt to ensure the performance of the recycled asphalt mixture. The 60℃ dynamic viscosity is an important parameter reflecting the ability of road asphalt to resist permanent deformation at high temperature, the 25℃ elastic recovery is an important parameter reflecting the toughness of road asphalt, and the 60℃ composite shear modulus is an important parameter reflecting the resistance of road asphalt to rutting. This scheme selects high-viscosity and high-elastic modified asphalt with a 60℃ composite shear modulus G*≥10KPa, a 60℃ dynamic viscosity ≥400,000 Pa·s, and a 25℃ elastic recovery of>95% as raw material, which is beneficial to improving the adhesion of new asphalt to new aggregates and asphalt recycling materials, thereby giving the recycled mixture asphalt high-temperature stability, high strength and high toughness and other properties, thereby increasing the stability of the road surface.

[0053] Finally, in order to ensure the performance of the in-situ hot-recycled asphalt mixture, this technical solution uses high-viscosity and high-elasticity modified asphalt to wrap the recycled asphalt material and coarse aggregate, and limits the type of high-strength and high-toughness in-situ hot-recycled asphalt mixture to a skeleton-dense asphalt mixture, so that when the amount of recycled asphalt material is higher than 60%, the asphalt mixture can still have high strength and high toughness, thereby ensuring the road performance of the recycled asphalt pavement.

[0054] To further illustrate, in step B, the grading of mineral materials in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is as follows: the pass rate of 16 mm sieve hole is 100%, the pass rate of 13.2 mm sieve hole is 90-100%, the pass rate of 9.5 mm sieve hole is 50-75%, the pass rate of 4.75 mm sieve hole is 20-34%, the pass rate of 2.36 mm sieve hole is 15-26%, the pass rate of 1.18 mm sieve hole is 14-24%, the pass rate of 0.6 mm sieve hole is 12-20%, the pass rate of 0.3 mm sieve hole is 10-16%, the pass rate of 0.15 mm sieve hole is 9-15% and the pass rate of 0.075 mm sieve hole is 8-12%.

[0055] The overall grading range of the preferred mineral aggregate is conducive to constructing an asphalt mixture with a dense skeleton structure with a rich surface texture and a high friction coefficient, so as to enhance the road performance and road performance of the recycled asphalt mixture.

[0056] It should be noted that the mineral aggregate includes old mineral aggregate in asphalt recycling material and newly added new mineral aggregate.

[0057] Further description, in step B, the high-viscosity and high-elastic modified asphalt includes SBS modifier, and calculated by mass percentage, the added amount of the SBS modifier is ≥10%.

[0058] Furthermore, when the amount of SBS modifier added is ≥10%, it can effectively improve the strength and toughness of the recycled asphalt mixture, and give the recycled asphalt mixture better road performance such as anti-rutting, anti-cracking, anti-fatigue and water damage resistance. In addition, when the amount of SBS modifier added is ≥10%, it is helpful to provide sufficient viscosity for the high-viscosity and high-elasticity modified asphalt, making it more encapsulating and bonding to the asphalt recycled material, further improving the performance of the recycled asphalt mixture.

[0059] Further description, in step B, the first coarse aggregate and the second coarse aggregate are any one of diabase, basalt and diorite.

[0060] Diabase, basalt and diorite all have the characteristics of high compressive strength and hardness, good road performance, which is conducive to ensuring the performance of recycled asphalt mixture.

[0061] Further, in step B, the mineral powder is limestone, and the apparent relative density of the mineral powder is greater than 2.50 g / cm 3 , the hydrophilic coefficient is less than 1, and the water content of the mineral powder is less than 1% calculated by mass percentage.

[0062] Limestone as mineral powder can effectively improve the corrosion resistance of recycled asphalt mixture, thereby effectively improving and improving the problems of damage and short service life of recycled asphalt pavement. In addition, the technical solution optimizes the apparent relative density, hydrophilicity coefficient and water content of the mineral powder, which is conducive to improving the cohesion of the mortar formed by it and modified asphalt, thereby more effectively enhancing the strength of the recycled asphalt mixture.

[0063] To further illustrate, steps B, C, D and E are specifically:

[0064] B. Determine the amount of high-viscosity and high-elastic modified asphalt, asphalt recycling material, new mineral material and regeneration agent according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared, and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared;

[0065] C. Preheat the high-viscosity and high-elasticity modified asphalt, asphalt recycling material, new mineral material and regeneration agent respectively;

[0066] D. Add the new mineral material and a part of the high-viscosity and high-elasticity modified asphalt into the preheated first mixing equipment according to the amount determined in step B, and mix them to obtain an oil-rich and large-particle asphalt mixture;

[0067] E. Add the asphalt recovery material into the preheated second mixing equipment according to the amount determined in step B, and then add the regeneration agent, oil-rich large-particle asphalt mixture and the remaining amount of high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture.

[0068] The technical solution adds a preferred regeneration agent to the formula of the regenerated asphalt mixture, and uses the regeneration agent to activate the performance of the old asphalt in the asphalt recycling material, which is beneficial to improving the performance of the regenerated asphalt mixture.

[0069] It should be noted that the type of regeneration agent can be a petroleum-based regeneration agent or a regeneration agent that complies with the provisions of the "Technical Specifications for Regeneration of Highway Asphalt Pavement" (JTG / T 5521-2019), and its type is not limited here.

[0070] Preferably, in step C, the preheating temperature of the new mineral material is 180-190°C, the preheating temperature of the high-viscosity and high-elasticity modified asphalt is 175-180°C, the preheating temperature of the asphalt recycling material is 140-150°C, and the preheating temperature of the regeneration agent is 140-150°C;

[0071] In step D, the preheating temperature of the first mixing equipment is 180-190°C;

[0072] In step E, the preheating temperature of the second mixing equipment is 140-150°C.

[0073] By limiting the preheating temperature of each raw material and mixing equipment, it is helpful to reduce the heat loss caused by temperature differences in the subsequent mixing process, improve the mixing efficiency, and ensure that all raw materials are at a similar temperature during mixing, which is conducive to the full fusion of the raw materials, ensure the adhesion of modified asphalt to other raw materials, make the recycled asphalt mixture bonded to form a whole, and ensure the relevant performance of the recycled asphalt mixture.

[0074] Further explanation: in step B, calculated by mass percentage, the high-strength and high-toughness in-situ hot-regenerated asphalt mixture includes 1.0-5.0% of high-viscosity and high-elasticity modified asphalt, 65-80% of asphalt recycling material, 15-28% of new mineral material and 0.04-0.16% of regeneration agent.

[0075] In this technical solution, by optimizing the addition amount of each raw material in the recycled asphalt mixture, while ensuring the relevant performance of the recycled asphalt mixture, the addition amount of asphalt recycled materials in the recycled asphalt mixture is as high as 65-80%, which is conducive to further reducing production costs.

[0076] Further explanation: in step D, calculated by mass ratio, the mixing ratio of the new mineral material and the high-viscosity and high-elasticity modified asphalt in the oil-rich large-particle asphalt mixture is (10-13):1.

[0077] In the present technical scheme, by limiting the mass mixing ratio of new mineral material and high-viscosity and high-elasticity modified asphalt in the oil-rich and large-particle asphalt mixture, it is beneficial to ensure that the new mineral material is completely wrapped and adhered by the high-viscosity and high-elasticity modified asphalt, thereby ensuring the performance of the oil-rich and large-particle asphalt mixture, and then ensuring the performance of the recycled asphalt mixture.

[0078] A high-strength and high-toughness in-situ hot-regenerated asphalt mixture, characterized in that it is prepared using the above-mentioned method for preparing the high-strength and high-toughness in-situ hot-regenerated asphalt mixture.

[0079] The present invention also proposes a method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture. The high-strength and high-toughness in-situ hot-regenerated asphalt mixture prepared by the method has high strength and toughness, which is beneficial to ensuring the road performance of the regenerated asphalt pavement.

[0080] A high-strength and high-toughness hot-regenerated asphalt mixture is used in a regenerated asphalt pavement, using the high-strength and high-toughness hot-regenerated asphalt mixture mentioned above, and the paving thickness of the ultra-high-strength and high-toughness hot-regenerated asphalt mixture is 4 to 5 cm.

[0081] This technical solution helps to ensure the performance of the regenerated asphalt pavement paved therefrom by optimizing the paving thickness of the in-situ hot-regenerated asphalt mixture.

[0082] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0083] Example 1

[0084] In this embodiment, the high-strength and high-toughness in-situ hot-regenerated asphalt mixture includes 3.91% of high-viscosity and high-elasticity modified asphalt, 70% of asphalt recycling material, 26% of new mineral material and 0.09% of petroleum-based regeneration agent according to the mass percentage calculation; the gradation of the mineral material in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is as follows: the pass rate of 16mm sieve hole is 100%, the pass rate of 13.2mm sieve hole is 98%, the pass rate of 9.5mm sieve hole is 65%, the pass rate of 4.75mm sieve hole is 25%, the pass rate of 2.36mm sieve hole is 23%, the pass rate of 1.18mm sieve hole is 20%, the pass rate of 0.6mm sieve hole is 16%, and the pass rate of 0.3 The passing rate of the sieve hole of mm is 13%, the passing rate of the sieve hole of 0.15mm is 10% and the passing rate of the sieve hole of 0.075mm is 8%; the 60℃ composite shear modulus G* of the high-viscosity and high-elasticity modified asphalt is 12KPa, the 60℃ dynamic viscosity is 420,000 Pa·s, and the elastic recovery at 25℃ is 96%; the high-viscosity and high-elasticity modified asphalt includes SBS modifier, and the addition amount of SBS modifier is 10% calculated by mass percentage; calculated by mass percentage, the new mineral material includes 60 parts of 10-15mm diabase, 33 parts of 5-10mm diabase and 7 parts of limestone; the apparent relative density of the mineral powder is 2.80g / cm 3 The hydrophilic coefficient is 0.9, and the water content of the mineral powder is 0.8% calculated by mass percentage.

[0085] In this embodiment, a method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture comprises the following steps:

[0086] A. Detect the old asphalt content, old asphalt properties and old mineral material gradation in the asphalt recycling material to obtain the test results;

[0087] B. Determine the dosage of high-viscosity and high-elasticity modified asphalt, asphalt recycling material, new mineral material and regeneration agent according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared;

[0088] C. Preheat the high-viscosity and high-elastic modified asphalt to 175°C for use, preheat the asphalt recycling material to 150°C for use, preheat the new mineral material to 180°C for use, and preheat the petroleum-based regeneration agent to 140°C for use;

[0089] D. Add the new mineral material and 50% of the high-viscosity and high-elasticity modified asphalt according to the amount determined in step B into the first mixing equipment at a temperature of 180° C. to obtain an oil-rich large-particle asphalt mixture;

[0090] E. According to the amount determined in step B, add the asphalt recovery material into the second mixing equipment at a temperature of 150°C for mixing, and then add the regeneration agent, oil-rich large-particle asphalt mixture and 50% high-viscosity and high-elasticity modified asphalt in sequence for mixing to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture; wherein the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is a skeleton-dense asphalt mixture.

[0091] Example 2

[0092] In this embodiment, the high-strength and high-toughness in-situ hot-regenerated asphalt mixture includes 2.89% of high-viscosity and high-elasticity modified asphalt, 75% of asphalt recycling material, 22% of new mineral material and 0.11% of petroleum-based regeneration agent according to the mass percentage calculation; the gradation of the mineral material in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is as follows: the passing rate of 16mm sieve hole is 100%, the passing rate of 13.2mm sieve hole is 90%, the passing rate of 9.5mm sieve hole is 60%, the passing rate of 4.75mm sieve hole is 30%, the passing rate of 2.36mm sieve hole is 23%, the passing rate of 1.18mm sieve hole is 18%, the passing rate of 0.6mm sieve hole is 15%, and the passing rate of 0.3 The passing rate of the sieve hole of 0.075mm is 9%, the passing rate of the sieve hole of 0.15mm is 12%, and the passing rate of the sieve hole of 0.075mm is 9%; the composite shear modulus G* of the high-viscosity and high-elasticity modified asphalt at 60℃ is 12KPa, the dynamic viscosity at 60℃ is 450,000 Pa·s, and the elastic recovery at 25℃ is 96%; the high-viscosity and high-elasticity modified asphalt includes SBS modifier, and the addition amount of SBS modifier is 11% calculated by mass percentage; calculated by mass percentage, the new mineral material includes 60 parts of 10-15mm diabase, 30 parts of 5-10mm diabase and 7 parts of limestone; the apparent relative density of the mineral powder is 3.00g / cm 3 The hydrophilic coefficient is 0.9, and the water content of the mineral powder is 0.7% calculated by mass percentage.

[0093] In this embodiment, a method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture comprises the following steps:

[0094] A. Detect the old asphalt content, old asphalt properties and old mineral material gradation in the asphalt recycling material to obtain the test results;

[0095] B. Determine the dosage of high-viscosity and high-elasticity modified asphalt, asphalt recycling material, new mineral material and regeneration agent according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared;

[0096] C. Preheat the high-viscosity and high-elastic modified asphalt to 180°C for use, preheat the asphalt recycling material to 150°C for use, preheat the new mineral material to 190°C for use, and preheat the petroleum-based regeneration agent to 140°C for use;

[0097] D. According to the amount determined in step B, add the new mineral material and 35% of the high-viscosity and high-elasticity modified asphalt into the first mixing equipment at a temperature of 190° C. to obtain an oil-rich large-particle asphalt mixture;

[0098] E. According to the amount determined in step B, add the asphalt recovery material into the second mixing equipment at a temperature of 150°C for mixing, and then add the regeneration agent, oil-rich large-particle asphalt mixture and 65% high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture; wherein the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is a skeleton-dense asphalt mixture.

[0099] Example 3

[0100] In this embodiment, the high-strength and high-toughness in-situ hot-regenerated asphalt mixture includes 3.88% of high-viscosity and high-elasticity modified asphalt, 78% of asphalt recycling material, 18% of new mineral material and 0.12% of petroleum-based regeneration agent according to the mass percentage calculation; the gradation of the mineral material in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is as follows: the pass rate of 16mm sieve hole is 100%, the pass rate of 13.2mm sieve hole is 95%, the pass rate of 9.5mm sieve hole is 68%, the pass rate of 4.75mm sieve hole is 33%, the pass rate of 2.36mm sieve hole is 23%, the pass rate of 1.18mm sieve hole is 16%, the pass rate of 0.6mm sieve hole is 15%, and the pass rate of 0.3 The passing rate of the sieve hole of mm is 13%, the passing rate of the sieve hole of 0.15mm is 9% and the passing rate of the sieve hole of 0.075mm is 8%; the composite shear modulus G* of the high-viscosity and high-elasticity modified asphalt at 60℃ is 10KPa, the dynamic viscosity at 60℃ is 400,000 Pa·s, and the elastic recovery at 25℃ is 96%; the high-viscosity and high-elasticity modified asphalt includes SBS modifier, and the addition amount of SBS modifier is 12% calculated by mass percentage; calculated by mass percentage, the new mineral material includes 65 parts of 10-15mm diabase, 27 parts of 5-10mm diabase and 8 parts of limestone; the apparent relative density of the mineral powder is 2.70g / cm 3 The hydrophilic coefficient is 0.8, and the water content of the mineral powder is 0.8% calculated by mass percentage.

[0101] In this embodiment, a method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture comprises the following steps:

[0102] A. Detect the old asphalt content, old asphalt properties and old mineral material gradation in the asphalt recycling material to obtain the test results;

[0103] B. Determine the dosage of high-viscosity and high-elasticity modified asphalt, asphalt recycling material, new mineral material and regeneration agent according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared;

[0104] C. Preheat the high-viscosity and high-elastic modified asphalt to 178°C for use, preheat the asphalt recycling material to 145°C for use, preheat the new mineral material to 180°C for use, and preheat the petroleum-based regeneration agent to 150°C for use;

[0105] D. Add the new mineral material and 30% of the high-viscosity and high-elasticity modified asphalt according to the amount determined in step B into the first mixing equipment at a temperature of 180° C. to obtain an oil-rich large-particle asphalt mixture;

[0106] E. According to the amount determined in step B, add the asphalt recovery material into the second mixing equipment at a temperature of 150°C for mixing, and then add the regeneration agent, oil-rich large-particle asphalt mixture and 70% high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture; wherein the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is a skeleton-dense asphalt mixture.

[0107] Comparative Example 1

[0108] The preparation method and raw materials of Comparative Example 1 are the same as those of Example 2, except that the asphalt in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture formula in Comparative Example 1 is ordinary modified asphalt.

[0109] Comparative Example 2

[0110] The preparation method and raw materials of Comparative Example 2 are the same as those of Example 2, except that the high-strength and high-toughness in-situ hot-regenerated asphalt mixture in Comparative Example 2 is a suspended dense asphalt mixture, and the grading of the mineral material in the regenerated asphalt mixture is as follows: 16 mm sieve hole pass rate is 100%, 13.2 mm sieve hole pass rate is 95%, 9.5 mm sieve hole pass rate is 75%, 4.75 mm sieve hole pass rate is 45%, 2.36 mm sieve hole pass rate is 35%, 1.18 mm sieve hole pass rate is 25%, 0.6 mm sieve hole pass rate is 17%, 0.3 mm sieve hole pass rate is 14%, 0.15 mm sieve hole pass rate is 10% and 0.075 mm sieve hole pass rate is 8%.

[0111] Comparative Example 3

[0112] The preparation method and raw materials of Comparative Example 3 are the same as those of Example 2, except that the high-strength and high-toughness in-situ hot-regenerated asphalt mixture in Comparative Example 3 is a skeleton void type asphalt mixture, and the grading of the mineral material in the regenerated asphalt mixture is as follows: 16 mm sieve hole pass rate is 100%, 13.2 mm sieve hole pass rate is 95%, 9.5 mm sieve hole pass rate is 70%, 4.75 mm sieve hole pass rate is 20%, 2.36 mm sieve hole pass rate is 15%, 1.18 mm sieve hole pass rate is 10%, 0.6 mm sieve hole pass rate is 8%, 0.3 mm sieve hole pass rate is 6%, 0.15 mm sieve hole pass rate is 5% and 0.075 mm sieve hole pass rate is 3%.

[0113] Comparative Example 4

[0114] The preparation method and raw materials of Comparative Example 4 are the same as those of Example 2, except that in Comparative Example 4, the preheated high-viscosity and high-elasticity modified asphalt, asphalt recycling material, new mineral material and petroleum-based regeneration agent are directly mixed in a second mixing equipment at a temperature of 150°C to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture.

[0115] The hot-regenerated asphalt mixture obtained in the embodiment and the comparative example was used to lay the regenerated asphalt pavement, and the laying thickness is shown in Table 1 below. The regenerated asphalt pavement after laying was tested for relevant performance according to the standards specified in the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), and the results are shown in Table 1 below.

[0116] Table 1 Relevant performance test results of recycled asphalt pavement

[0117]

[0118] From the performance test results in Table 1, it can be seen that the relevant performance of the regenerated asphalt pavement obtained by this technical solution is much higher than the open standard of regenerated asphalt pavement specified in the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). On the premise of increasing the amount of recycled asphalt materials and greatly reducing production costs, the in-situ hot-regenerated asphalt mixture has excellent strength and toughness, ensuring that the regenerated asphalt pavement can meet the requirements of places with high road performance.

[0119] In Comparative Example 1, due to the use of ordinary modified asphalt, the performance of the recycled asphalt pavement paved therefrom was significantly reduced.

[0120] In Comparative Examples 2 and 3, since the recycled asphalt mixtures used suspended dense asphalt mixtures and skeleton void asphalt mixtures respectively, the performance of the recycled asphalt pavements paved therefrom significantly decreased.

[0121] In Comparative Example 4, since the preheated high-viscosity and high-elastic modified asphalt, asphalt recycling material, new mineral material and petroleum-based regeneration agent are directly mixed, the new mineral material is not easy to be evenly coated and is partially exposed, which in turn affects the performance of the in-situ hot-regenerated asphalt mixture, resulting in a significant decrease in the performance of the regenerated asphalt pavement.

[0122] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A method for preparing high-strength and high-toughness in-situ hot-regenerated asphalt mixture, characterized in that: The following steps are involved: A. Detect the old asphalt content, old asphalt properties and old mineral material gradation in the asphalt recycling material to obtain the test results; B. Determine the amount of high-viscosity and high-elastic modified asphalt, asphalt recycling material and new mineral material according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared; Wherein, calculated by weight, the new mineral material comprises 50-60 parts of a first coarse aggregate of 10-15 mm, 25-35 parts of a second coarse aggregate of 5-10 mm and 6-8 parts of mineral powder; the 60°C composite shear modulus G* of the high-viscosity and high-elasticity modified asphalt is ≥10KPa, the 60°C dynamic viscosity is ≥400,000 Pa·s, and the 25°C elastic recovery is >95%; C. Preheat the high-viscosity and high-elasticity modified asphalt, asphalt recycling material and new mineral material respectively; D. Add the new mineral material and a part of the high-viscosity and high-elasticity modified asphalt into the preheated first mixing equipment according to the amount determined in step B, and mix them to obtain an oil-rich and large-particle asphalt mixture; E. Add the asphalt recovery material into the preheated second mixing equipment according to the amount determined in step B, and then add the oil-rich large-particle asphalt mixture and the remaining amount of high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture; The high-strength and high-toughness in-situ hot-regenerated asphalt mixture is a skeleton-dense asphalt mixture, and calculated by mass percentage, the amount of recycled asphalt in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is greater than 60%.

2. The method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture according to claim 1, characterized in that: In step B, the grading of mineral materials in the high-strength and high-toughness in-situ hot-regenerated asphalt mixture is as follows: the pass rate of 16 mm sieve hole is 100%, the pass rate of 13.2 mm sieve hole is 90-100%, the pass rate of 9.5 mm sieve hole is 50-75%, the pass rate of 4.75 mm sieve hole is 20-34%, the pass rate of 2.36 mm sieve hole is 15-26%, the pass rate of 1.18 mm sieve hole is 14-24%, the pass rate of 0.6 mm sieve hole is 12-20%, the pass rate of 0.3 mm sieve hole is 10-16%, the pass rate of 0.15 mm sieve hole is 9-15% and the pass rate of 0.075 mm sieve hole is 8-12%.

3. The method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture according to claim 1, characterized in that: In step B, the high-viscosity and high-elastic modified asphalt includes an SBS modifier, and calculated by mass percentage, the added amount of the SBS modifier is ≥10%.

4. The method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture according to claim 1, characterized in that: In step B, the first coarse aggregate and the second coarse aggregate are any one of diabase, basalt and diorite.

5. The high-strength and high-toughness in-situ hot-regenerated asphalt mixture according to claim 1, characterized in that: In step B, the mineral powder is limestone, and the apparent relative density of the mineral powder is greater than 2.50 g / cm 3 , the hydrophilic coefficient is less than 1, and the water content of the mineral powder is less than 1% calculated by mass percentage.

6. The method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture according to claim 1, characterized in that: Steps B, C, D and E are specifically: B. Determine the amount of high-viscosity and high-elastic modified asphalt, asphalt recycling material, new mineral material and regeneration agent according to the test results, the gradation of the hot-regenerated asphalt mixture to be prepared, and the gradation of the mineral material in the hot-regenerated asphalt mixture to be prepared; C. Preheat the high-viscosity and high-elasticity modified asphalt, asphalt recycling material, new mineral material and regeneration agent respectively; D. Add the new mineral material and a part of the high-viscosity and high-elasticity modified asphalt into the preheated first mixing equipment according to the amount determined in step B, and mix them to obtain an oil-rich and large-particle asphalt mixture; E. Add the asphalt recovery material into the preheated second mixing equipment according to the amount determined in step B, and then add the regeneration agent, oil-rich large-particle asphalt mixture and the remaining amount of high-viscosity and high-elasticity modified asphalt in sequence to obtain a high-strength and high-toughness in-situ hot-regenerated asphalt mixture.

7. The method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture according to claim 6 is characterized in that: In step B, calculated by mass percentage, the high-strength and high-toughness in-situ hot-regenerated asphalt mixture includes 1.0-5.0% of high-viscosity and high-elasticity modified asphalt, 65-80% of asphalt recycling material, 15-28% of new mineral material and 0.04-0.16% of regeneration agent.

8. A method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture according to claim 1, characterized in that: In step D, calculated by mass ratio, the mixing ratio of the new mineral material and the high-viscosity and high-elasticity modified asphalt in the oil-rich large-particle asphalt mixture is (10-13):

1.

9. A high-strength and high-toughness in-situ hot-regenerated asphalt mixture, characterized in that: The asphalt mixture is prepared using the method for preparing a high-strength and high-toughness in-situ hot-regenerated asphalt mixture as described in any one of claims 1 to 8.

10. Application of high-strength and high-toughness in-situ hot-regenerated asphalt mixture in regenerated asphalt pavement, characterized in that: The high-strength and high-toughness in-situ hot-regenerated asphalt mixture as described in claim 9 is used, and the paving thickness of the ultra-high-strength and high-toughness in-situ hot-regenerated asphalt mixture is 4 to 5 cm.

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