Rapid deep repairing method for asphalt pavement cracks based on microwave heating technology

Abstract

The invention belongs to the technical field of pavement repair, and mainly relates to an asphalt pavement crack rapid deep repair method based on a microwave heating technology, which comprises the following steps: firstly, removing dust and moisture in cracks, then adding repair materials into the cracks, and after the repair materials are added, carrying out heating treatment on crack areas by adopting the microwave heating technology, and after heating is completed, the crack area is compacted immediately, and then repairing is completed. Energy can be quickly and efficiently transferred into the asphalt pavement through microwave heating, energy loss is reduced, accurate heating of different asphalt pavements can be achieved by adjusting the heating time and power, the repairing efficiency can be effectively improved through microwave heating, energy consumption is reduced, more accurate deep-layer crack repairing is achieved, and the service life of the asphalt pavement is prolonged. The construction cost for repairing the asphalt pavement cracks is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of pavement repair, and mainly relates to a method for quickly and deeply repairing cracks on an asphalt pavement based on a microwave heating technology. Background Art

[0002] In about 80% of the roads and highways in my country, the asphalt pavement has cracks of varying degrees, especially in urban roads and highways with dense traffic, where the crack phenomenon is more obvious. According to statistics from the China Highway Society, after three years of operation, about 65% to 75% of the road sections will have longitudinal or transverse cracks of varying degrees. Once cracks appear on the asphalt pavement, they are prone to crack expansion, water damage, fragmentation and other diseases, seriously endangering driving safety. Therefore, studying and solving the problem of asphalt pavement cracks has become an important task in my country's road construction and maintenance.

[0003] Traditional asphalt pavement crack repair methods such as grouting and taping have certain limitations. The grouting method requires heating the cracks and asphalt materials before construction, which is a cumbersome and time-consuming process. The taping method mainly isolates the cracks from the external environment by covering, which makes it difficult to effectively repair the deep cracks. Some new repair methods that have emerged subsequently, such as pressurized grouting, milling repair, and thermal regeneration, have complex processes, long construction cycles, and are prone to disrupting traffic. Therefore, it is particularly important to develop a method that can quickly and deeply repair cracks while reducing construction costs. Summary of the invention

[0004] The present invention provides a method for rapid deep repair of asphalt pavement cracks based on microwave heating technology, so as to solve the problem that the asphalt pavement crack repair method in the prior art cannot take into account both deep repair of cracks and reduction of construction costs.

[0005] To solve the above problems, the present invention adopts the following technical solutions: A method for rapid deep repair of asphalt pavement cracks based on microwave heating technology, comprising the following steps: first, dust and moisture in the cracks are removed, then repair materials are added to the cracks, and after the addition is completed, the crack area is heated using microwave heating technology, and after the heating is completed, the crack area should be compacted immediately to complete the repair.

[0006] It has the following beneficial effects: microwave heating can quickly and efficiently transfer energy to the interior of the asphalt pavement, reducing energy loss, and by adjusting the heating time and power, precise heating of different asphalt pavements can be achieved. Microwave heating can effectively improve repair efficiency, reduce energy consumption, and achieve more accurate deep-seated crack repair, reducing the construction cost of repairing asphalt pavement cracks; adding repair materials into the cracks can better repair asphalt pavement cracks.

[0007] Furthermore, the repair material is modified emulsified asphalt.

[0008] Furthermore, the modified emulsified asphalt consists of asphalt, water, an emulsifier and a modifier.

[0009] Furthermore, the asphalt pavement cracks are heated to 40°C-80°C.

[0010] It has the following beneficial effects: by heating the cracks in the asphalt pavement to 40℃-80℃, the self-healing properties of the asphalt mixture will be improved, which will facilitate the subsequent closure of the cracks and prevent damage to the pavement caused by excessive temperature.

[0011] Further, the asphalt pavement cracks are heated to 67°C.

[0012] Furthermore, the microwave heating time is 1-200s.

[0013] Furthermore, the microwave heating time is 20 s.

[0014] Furthermore, the microwave heating power is 1000W-6000W.

[0015] Furthermore, the microwave heating power is 4000W. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0017] Various non-limiting embodiments of the present invention are described in detail below. Any number of elements is used for illustration rather than limitation, and any naming is only used for distinction without any limiting meaning. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0018] In order to effectively remove moisture from cracks in asphalt pavement, microwave heating can be directly performed on the cracks in asphalt pavement by adjusting the microwave power and heating time. The principle of this method is that microwaves convert electromagnetic energy into thermal energy by causing water molecules to vibrate and rub at high speed, thereby heating water and inducing a phase transition from liquid water to water vapor. The following experiment verifies this process: First, 20g of water was poured into a polytetrafluoroethylene beaker and placed in a microwave oven, where it was heated for 20 seconds at 4000W. After heating, the mass of the remaining water in the beaker was measured to be 17.8g, and the temperature was 86.9℃. The experimental results show that the temperature of water molecules rises significantly under the action of microwaves, which in turn triggers a phase transition.

[0019] Secondly, a 617.3g asphalt mixture specimen was placed in a beaker filled with water and soaked for two hours, so that one end was partially wetted, and its mass was measured to be 618g. Subsequently, the asphalt mixture specimen was placed in a microwave oven and heated at a power of 4000W for 20 seconds. After heating, the mass of the asphalt mixture specimen was measured to be 617.3g, and the temperature of the soaked end was 65.2℃. This result shows that when asphalt mixture and water coexist, both can interact with microwaves, thereby increasing their own temperature.

[0020] In summary, microwave heating technology can effectively remove moisture from asphalt pavement cracks, and by adjusting the power and heating time, rapid drying of asphalt pavement cracks can be achieved.

[0021] Method for repairing cracks with a width less than 3 mm A method for rapid deep repair of cracks in asphalt pavement based on microwave heating technology, comprising the following steps: first, dust and debris in the cracks are removed, and then the crack area of ​​the asphalt pavement is heated by microwave heating. This process not only effectively removes moisture in the cracks, but also raises the temperature of the crack area to about 67°C, thereby improving the self-healing ability of the asphalt mixture, wherein the microwave heating time is 20 seconds and the microwave heating power is 4000 W. Afterwards, the crack area is quickly compacted to close the cracks and complete the repair.

[0022] Among them, microwave heating is a heating method that uses microwaves to generate heat inside the asphalt pavement. For asphalt mixtures containing water, water molecules are polar molecules. Under the action of microwaves, the water temperature rises rapidly and evaporates, while transferring heat to the asphalt mixture, effectively promoting the heating and temperature rise of the crack area.

[0023] Microwave energy acts directly on the inside of the asphalt pavement, causing the entire crack area of ​​the asphalt pavement to be heated at the same time. There is no need to gradually transfer heat from the outside to the inside through heat conduction, so the heating speed is much faster than traditional heating methods.

[0024] Microwave heating is the overall heating of the interior of the asphalt pavement. Unlike traditional heating methods, which are prone to overheating of the surface while not heating the interior thoroughly, this can make the cracked area of ​​the asphalt pavement heated more evenly.

[0025] Microwave heating is achieved by directly applying electromagnetic waves to the heated crack area, efficiently converting electromagnetic energy into thermal energy, reducing energy loss in the intermediate heat transfer link. Therefore, it has higher thermal efficiency and relatively good energy-saving effects.

[0026] The temperature and degree of heating can be precisely controlled by adjusting the microwave power and heating time to meet different heating needs.

[0027] In this embodiment, microwave heating is used to heat the cracks in the asphalt pavement to 67°C. The self-healing properties of the asphalt mixture will be improved, and the asphalt binder in the crack area will soften, thereby enhancing the adhesion and fluidity of the material, which is beneficial for subsequent compaction and promotes crack closure.

[0028] When tiny cracks or damage appear on the asphalt pavement, the asphalt will undergo viscous flow under the combined effects of temperature and applied force. The asphalt molecules will move toward the cracks or damage, filling the gaps and achieving a certain degree of healing.

[0029] Appropriate high temperature is conducive to the viscous flow of asphalt and promotes the self-healing process. At higher temperatures, the mobility of asphalt molecules is enhanced, and cracks can be filled more quickly. However, too high a temperature may cause asphalt aging and affect the mechanical properties of the asphalt pavement; too low a temperature will increase the viscosity of asphalt, which is not conducive to self-healing. Therefore, a suitable temperature is required.

[0030] There are intermolecular forces such as van der Waals forces between asphalt molecules. After damage occurs, the intermolecular forces will cause the asphalt molecules to rearrange and combine, causing the molecules on the crack surface to attract and connect with each other, which helps the cracks to close and heal.

[0031] In other embodiments, the asphalt pavement cracks may be heated to one of 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, and 80°C.

[0032] In other embodiments, the microwave heating time is one of 1s, 5s, 10s, 20s, 50s, 60s, 120s, and 200s.

[0033] In other embodiments, the microwave heating power is one of 1000W, 2000W, 3000W, 5000W, and 6000W.

[0034] Microwave heating can quickly and efficiently transfer energy to the interior of the asphalt pavement, reducing energy loss, and by adjusting the heating time and power, precise heating of different asphalt pavements can be achieved. Microwave heating can effectively improve repair efficiency, reduce energy consumption, and achieve more accurate deep crack repair, reducing the construction cost of repairing asphalt pavement cracks.

[0035] The self-healing property can automatically repair tiny cracks and damages, prevent the cracks from further expanding, thereby delaying the damage process of the asphalt pavement and extending the service life of the asphalt pavement. It also reduces the frequency and workload of asphalt pavement maintenance, reducing maintenance costs. For some minor damages, there is no need for immediate manual repair, saving maintenance materials and labor costs. At the same time, it can repair the damage of the asphalt pavement in time, maintain the flatness and integrity of the asphalt pavement, improve the safety and comfort of vehicle driving, and reduce traffic accidents caused by asphalt pavement diseases.

[0036] The following experiments verify this process: First, take an asphalt mixture specimen with a 2mm wide crack, clean the crack, and then place it in a microwave oven and heat it at 4000W for 20 seconds. After heating, squeeze the crack to close it, and place the asphalt mixture beam in a ventilated and dry environment. After three days of curing, the asphalt mixture beam did not crack again, proving that the crack has been successfully repaired.

[0037] Next, take another cracked asphalt mixture beam and heat it under the same microwave heating conditions. After heating, the surface temperature of the crack was measured to be 67.8°C. Subsequently, the asphalt mixture beam was completely destroyed along the crack, and the temperature of the damaged part inside the fracture surface was measured to be 59.8°C. The temperature difference between the two was 8.0°C, accounting for about 11.8% of the surface temperature. Although there is a certain temperature gradient, the internal temperature still reaches a high level, indicating that microwaves can penetrate the material and achieve deep heating of the crack area, providing a good thermal environment for the softening and self-healing of the asphalt binder.

[0038] Method for repairing cracks with a width greater than 3 mm A method for rapid deep repair of asphalt pavement cracks based on microwave heating technology, comprising the following steps: first, dust and moisture in the cracks are removed, then repair materials are added to the cracks, and after the addition is completed, the crack area is heated using microwave heating technology, and after the heating is completed, the crack area should be compacted immediately to complete the repair.

[0039] The experiment to verify the repair method is as follows: This experiment uses the healing rate as the basis for the effect of crack repair, and uses microwave heating technology to repair cracked asphalt mixture specimens to simulate the repair of asphalt pavement cracks. The ratio of the maximum bending-tensile strain during the secondary loading after healing to the maximum bending-tensile strain during the initial loading is used as the healing rate, as shown in the following formula: (Formula 1) —— healing rate; ——The maximum bending strain during initial loading; ——Maximum bending strain during secondary loading.

[0040] in , According to formula 2, we can get: (Formula 2) ——Bending and tensile strain of the specimen at failure ( ); h——the height of the test piece across the interruption (mm), which is 35mm in this embodiment; d——maximum deflection at mid-span when the specimen fails (mm); L——span of the specimen (mm), which is 200 mm in this embodiment.

[0041] (1) Obtain the maximum bending strain during initial loading Take three prismatic asphalt mixture beams with a length of 250mm±2.0mm, a width of 30mm±2.0mm, and a height of 35mm±2.0mm and place them in a freezer. Adjust the temperature of the freezer to -10℃ and keep it warm for 4 hours to keep the internal and external temperatures of the asphalt mixture beams consistent. Take the asphalt mixture beams out of the freezer and immediately place them symmetrically on the press base, with the up and down directions of the specimens consistent with the directions when the specimens were formed.

[0042] Set the press to a loading rate of 50 mm / min, then start the press to apply a concentrated load at the center of the span at a specified rate until the specimen is destroyed. The recorder also records the change in mid-span deflection, and takes the maximum mid-span deflection d when the specimen is destroyed. The experiment is conducted three times and two sets of data d are taken that are close to each other. 1 =24.357mm, d 2 =24.548mm, calculate its average value △d 3 =24.453mm, according to the experimental results, h=35mm, average value △d 3 =24.453mm, L=200mm are substituted into formula 2 to calculate the bending strain at failure. , that is, the maximum bending strain at the initial loading .

[0043] According to the above data and formula, the maximum bending strain at the initial loading is obtained: =0.1284 .

[0044] (2) Obtain the maximum bending strain during secondary loading The broken asphalt mixture beam in (1) was used as the experimental object. The asphalt mixture beam was first cleaned and dried. Four groups of experimental conditions were set up, and each group of experiments was repeated three times to simulate the influence of different conditions on the repair effect of asphalt pavement cracks.

[0045] 1) The first group of experiments simulated the effect of crack repair using modified emulsified asphalt under wet conditions. The cross section of the asphalt mixture beam was immersed in a beaker filled with water, ensuring that the water level just covered the cross section. After standing for 2 hours, it was taken out and 0.3g of modified emulsified asphalt was evenly applied. The cross sections were then spliced ​​and placed in a ventilated and dry environment for curing. The modified emulsified asphalt in this embodiment is composed of asphalt, water, emulsifier, and modifier.

[0046] 2) The second set of experiments simulated the effect of using modified emulsified asphalt to repair cracks in a dry environment. 0.5g of modified emulsified asphalt was evenly applied on the cross section of the specimen, and then the cross section was spliced ​​and placed in a ventilated and dry environment for curing.

[0047] 3) The third group of experiments simulated the effect of repairing cracks using microwave heating technology and modified emulsified asphalt. 0.5g of modified emulsified asphalt was evenly applied on the cross section of the specimen, and then the specimen was placed in a microwave oven with a power setting of 4000W and heated for 20 seconds to promote the evaporation of water in the emulsified asphalt and accelerate demulsification. After heating, the cross sections were spliced ​​and placed in a ventilated and dry environment for curing.

[0048] 4) The fourth group of experiments simulated the use of asphalt to repair cracks in asphalt pavement. 1.4g of modified asphalt was evenly applied directly on the cross section of the specimen, and the cross sections were spliced ​​together and placed in a ventilated and dry environment for maintenance.

[0049] After three days of curing, the healed specimens were loaded for the second time, and the loading conditions were the same as the initial loading. During the loading process, the maximum deflection d at the mid-span of each group of specimens at failure was recorded. Two similar experimental data were selected for each group of experiments, and their average value △d was calculated. 3 , the specific data are shown in Table 1.

[0050] Table 1 Maximum mid-span deflection of each group of specimens at failure

[0051] The bending and tensile strain at failure is calculated according to Formula 2, and the average value of the maximum deflection d at the mid-span is shown in Table 2: Table 2 Bending and tensile strains of each group of specimens at failure

[0052] (3) Calculate the healing rate of crack repair of specimens under different conditions Substitute the calculated maximum bending strain during secondary loading and the maximum bending strain during initial loading into formula 1. The calculated healing rate is shown in Table 3: Table 3 Healing rate of each group of specimens

[0053] Compared with the second group, the first group applied less emulsified asphalt to the cracks. The main reason is that when the cracks are wet, the water adheres to the crack surface and occupies part of the interface space, thus reducing the effective coating amount of the repair material. At the same time, the water will also interfere with the interfacial bonding between the emulsified asphalt and the asphalt mixture, weakening the repair effect. Therefore, in order to ensure the quality of crack repair, the water in the cracks must be thoroughly removed before construction.

[0054] Comparing the experimental results of the second and third groups, when both used modified emulsified asphalt as the repair material, the healing rate of the asphalt mixture beams heated by short-term microwaves was 7.79% higher than that of the unheated asphalt mixture beams. This shows that microwave heating can quickly and deeply repair asphalt pavement cracks.

[0055] Comparing the experimental results of the third and fourth groups, the healing rate of the asphalt mixture beams using modified emulsified asphalt combined with microwave heating technology is close to that of the asphalt mixture beams using modified asphalt. Since the amount of modified asphalt is much larger than that of emulsified asphalt and its cost is higher, when repairing cracks in asphalt pavement, the use of microwave heating technology combined with modified emulsified asphalt can not only achieve rapid and deep repair of cracks, but also significantly reduce construction costs.

Claims

1. A method for rapid deep repair of asphalt pavement cracks based on microwave heating technology, characterized in that: The following steps are involved: First, remove the dust and moisture in the cracks, then add repair materials into the cracks. After adding, use microwave heating technology to heat the crack area. After heating, the crack area should be compacted immediately to complete the repair.

2. According to claim 1, a method for rapid deep repair of asphalt pavement cracks based on microwave heating technology is characterized in that: The repair material is modified emulsified asphalt.

3. The method for rapid deep repair of asphalt pavement cracks based on microwave heating technology according to claim 2 is characterized in that: The modified emulsified asphalt consists of asphalt, water, emulsifier and modifier.

4. A method for rapid deep repair of asphalt pavement cracks based on microwave heating technology according to any one of claims 1-3, characterized in that: The asphalt pavement cracks are heated to 40°C-80°C.

5. The method for rapid deep repair of asphalt pavement cracks based on microwave heating technology according to claim 4 is characterized in that: The asphalt pavement cracks were heated to 67°C.

6. The method for rapid deep repair of asphalt pavement cracks based on microwave heating technology according to claim 5 is characterized in that: The microwave heating time is 1-200s.

7. The method for rapid deep repair of asphalt pavement cracks based on microwave heating technology according to claim 6 is characterized in that: The microwave heating time was 20 s.

8. The method for rapid deep repair of asphalt pavement cracks based on microwave heating technology according to claim 7 is characterized in that: The microwave heating power is 1000W-6000W.

9. The method for rapid deep repair of asphalt pavement cracks based on microwave heating technology according to claim 8 is characterized in that: The microwave heating power is 4000W.

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