A method of pavement seal coating
By mixing hot asphalt and emulsified asphalt to form a foamed asphalt layer, the problems of low construction efficiency of emulsified asphalt and difficulty in controlling the amount of hot asphalt sprayed are solved, realizing an efficient and economical road sealing method, and improving road quality and durability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN ZHONGLI ASPHALT CO LTD
- Filing Date
- 2026-03-24
- Publication Date
- 2026-05-29
Smart Images
Figure CN122105928A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of highway construction and maintenance technology, and in particular to a method for road surface sealing. Background Technology
[0002] Synchronous chip seal technology involves using a synchronous seal vehicle to spread aggregate while simultaneously applying asphalt tack coat. The aggregate falls onto the asphalt tack coat, quickly forming a road surface layer. It is often used as a lower or upper seal coat for road surfaces.
[0003] Hot asphalt or emulsified asphalt is generally used as the tack coat. Emulsified asphalt can be applied at room temperature, but it needs to undergo demulsification and dehydration before forming a stable and strong asphalt layer. The demulsification and dehydration process for emulsified asphalt is time-consuming and significantly affected by weather conditions; strong winds, temperature drops, and rain can all prolong the curing period. Therefore, using emulsified asphalt for road sealing is time-consuming, and emulsifying some high-viscosity, low-penetration hot asphalt is difficult. Using emulsified asphalt for asphalt layer preparation has certain drawbacks in terms of both construction efficiency and raw material preparation.
[0004] Hot asphalt has strong adhesive properties and does not require a curing period, but the application rate must be strictly controlled. Excessive application of hot asphalt can lead to bleeding, while insufficient application will result in poor adhesion of the aggregate. Furthermore, petroleum asphalt, such as 70# and 90# petroleum asphalt, typically has a softening point of 46℃-47℃. In the high temperatures of summer, the ground temperature exceeds this softening point, causing the petroleum asphalt to melt and lose its adhesive properties. Therefore, to improve the adhesion and high-temperature stability of petroleum asphalt, it is usually necessary to modify it to increase its softening point and adhesive properties. However, this also results in modified asphalt with higher viscosity, making it more difficult to control the uniformity of application.
[0005] Therefore, there is a need for an economical and efficient method for synchronous chip seal to obtain a road seal of superior quality. Summary of the Invention
[0006] This application provides a method for road sealing that can obtain a road sealing layer with better asphalt layer pull-out strength and better coating effect between crushed stone and asphalt layer at a lower cost.
[0007] The technical solution of this application embodiment is implemented as follows: This application provides a method for road sealing, the method comprising: S1, spraying foamed asphalt onto the road surface to form a foamed asphalt tack coat, wherein the foamed asphalt includes hot asphalt and emulsified asphalt; S2, spreading crushed stone onto the foamed asphalt tack coat to complete the road sealing.
[0008] In some implementations, the mass of the emulsified asphalt in the foamed asphalt is 5%-15% of the mass of the hot asphalt.
[0009] In some embodiments, foamed asphalt is prepared by the following steps: spraying emulsified asphalt to obtain an emulsified asphalt fog curtain; spraying hot asphalt to obtain a hot asphalt fog curtain; mixing the emulsified asphalt fog curtain and the hot asphalt fog curtain to foam, thereby obtaining foamed asphalt; wherein the temperature of the hot asphalt is 140-190°C; and / or the temperature of the emulsified asphalt is 20-60°C.
[0010] In some implementations, the method further includes repeating steps S1 and S2 at least once.
[0011] In some implementations, step S2 includes: after the foamed asphalt has expanded to its maximum volume, spreading gravel onto the foamed asphalt tack coat to complete the road seal.
[0012] In some embodiments, the hot asphalt comprises a first petroleum asphalt or a modified petroleum asphalt, wherein the modified petroleum asphalt comprises a modifier and the first petroleum asphalt, wherein the modifier is selected from one or more of anti-rutting masterbatch, styrene-butadiene-styrene block copolymer, rubber powder, natural asphalt, coal liquefaction asphalt and resin; and / or the first petroleum asphalt is selected from one or more of 20# petroleum asphalt, 70# petroleum asphalt, 90# petroleum asphalt and 110# petroleum asphalt.
[0013] In some embodiments, the emulsified asphalt comprises, by mass fraction: 30%-50% second petroleum asphalt, 70%-50% water, and 0.5%-2% surfactant; wherein the second petroleum asphalt comprises: 50# petroleum asphalt, 70# petroleum asphalt, 90# petroleum asphalt, or 110# petroleum asphalt.
[0014] In some embodiments, the surfactant includes cationic surfactants, nonionic surfactants, or amphiphilic surfactants.
[0015] In some implementations, the application rate of foamed asphalt is 1.2-2.5 kg / m³. 2 The preferred value is 1.5-2.2 kg / m³. 2 .
[0016] In some embodiments, the particle size range of the crushed stone is selected from any of the following: 3-5 mm, 5-8 mm, 7-11 mm and 10-15 mm; and / or the coverage of the crushed stone is 95%-100%.
[0017] In some implementations, the volume expansion rate of the foamed asphalt is greater than or equal to 3 times, preferably 4-8 times.
[0018] In some implementations, the half-life of the foamed asphalt is greater than or equal to 6 seconds, preferably greater than or equal to 8 seconds.
[0019] This application provides a road sealing device, which includes: a work vehicle, an asphalt spraying system, and a gravel spreading system, wherein the asphalt spraying system and the gravel spreading system are mounted on the work vehicle; wherein the asphalt spraying system is used to spray foamed asphalt to form a foamed asphalt tack coat, and the gravel spreading system is used to spread gravel on the foamed asphalt tack coat.
[0020] In some embodiments, the asphalt spraying system includes a hot asphalt storage tank and a hot asphalt spraying device connected to the hot asphalt storage tank, an emulsified asphalt storage tank and an emulsified asphalt spraying device connected to the emulsified asphalt storage tank; the hot asphalt spraying device is used to spray hot asphalt, the emulsified asphalt spraying device is used to spray emulsified asphalt, and the sprayed hot asphalt and the sprayed emulsified asphalt come into contact before falling to the ground.
[0021] In some embodiments, the emulsified asphalt spraying device is located in front of the hot asphalt along the vehicle's direction of travel, and the spraying direction of the hot asphalt spraying device and the spraying direction of the emulsified asphalt spraying device are directed towards the rear along the vehicle's direction of travel.
[0022] In some embodiments, the road seal device further includes a temperature control system for maintaining the temperature of the asphalt spraying system.
[0023] The embodiments of this application have the following beneficial effects: This application utilizes emulsified asphalt and hot asphalt as raw materials to prepare foamed asphalt, which simplifies the foaming process and makes it easier to control. Furthermore, using foamed asphalt for asphalt layer preparation allows for easier control of the application rate, resulting in a foamed asphalt layer with high volume expansion and a long half-life. This allows for increased coating area between the foamed asphalt and aggregate during subsequent simultaneous application of crushed stone, extending the workable time and facilitating on-site control. The road seal obtained using this method exhibits superior asphalt layer pull-out strength, better aggregate-asphalt coating, and reduced material loss, thus enhancing the road seal's durability and further reducing the cost of road seal application. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the road seal device in this application. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0026] In this document, the term "expansion rate" refers to the ratio of the maximum volume of asphalt reached at the moment of foaming to the original volume of the unfoamed asphalt. The expansion rate can be tested using methods known in the art. An exemplary test method includes placing a marked measuring rod in a test barrel, measuring the original asphalt height and the height of the foamed asphalt at its maximum expansion, and calculating the expansion rate by using the ratio.
[0027] In this document, the term "half-life" refers to the time (in seconds) it takes for foamed asphalt to decay from its maximum volume to half of its maximum volume. The half-life can be tested using methods known in the art. An exemplary testing method includes: starting a timer when the volume of the foamed asphalt expands to its maximum, continuing observation until the volume of the foamed asphalt decreases to half of its maximum volume, and then stopping the timer; the time obtained is the half-life, measured in seconds (s).
[0028] Simultaneous chip seal refers to the process of immediately spreading crushed stone on the asphalt layer after the asphalt layer has been applied, so that the crushed stone is covered on the asphalt layer, forming a waterproof and non-slip road seal.
[0029] The relevant technology uses hot asphalt or emulsified asphalt as the tack coat, and an asphalt layer can be obtained through road construction. However, from the perspective of construction efficiency or road quality, there are certain drawbacks in using hot asphalt or emulsified asphalt for asphalt layer preparation.
[0030] Hot asphalt, due to its strong binding force, is difficult to control in terms of application rate when spreading asphalt layers, and the resulting road surface has poor uniformity. While emulsified asphalt has suitable viscosity, it requires a long curing period after application, which is further prolonged by adverse weather conditions, making it difficult to control construction costs.
[0031] Foamed asphalt technology is a process that involves injecting a small amount of water into hot asphalt. The water rapidly vaporizes and generates steam impact, causing the asphalt to expand instantly and its viscosity to decrease. This technology effectively reduces the construction viscosity of asphalt and achieves uniform coating of aggregates through the instantaneous volume expansion of the foamed asphalt.
[0032] Using foamed asphalt for asphalt tack coat application avoids the long curing period required for demulsification and dehydration associated with emulsified asphalt application, and also avoids the difficulty in precisely controlling the application rate when using hot asphalt due to its higher viscosity. Foaming of the asphalt can be performed in a foaming device before spraying, or water and hot asphalt can be sprayed separately and then foamed upon contact in the air.
[0033] Among these methods, foaming asphalt using a foaming device can currently be achieved using a synchronized chip seal pavement truck equipped with a mechanical foaming unit. The core of this mechanical foaming unit is its foaming chamber. Hot asphalt and water are injected into the foaming chamber under precisely set pressure and flow rates to complete the foaming process. The foamed asphalt is then sprayed out of the foaming chamber and applied to the road surface to form an asphalt layer. Therefore, this foaming method places high demands on the control system of the foaming device, resulting in higher construction costs. Furthermore, the preparation of foamed asphalt using a mechanical foaming device is an intermittent operation; only a certain amount of foamed asphalt can be prepared at a time, requiring re-preparation after use, making continuous operation impossible.
[0034] Alternatively, a simple foaming device can be used to foam the asphalt, which involves spraying water onto the hot asphalt to achieve foaming. To ensure sufficient contact between the sprayed water and the hot asphalt, allowing the water to fully vaporize, the water spray pipe is usually positioned below the hot asphalt spray pipe. This can easily cause the water to fall onto the road surface before the asphalt, wetting the surface and resulting in poor adhesion between the subsequently applied foamed asphalt and the road surface, significantly affecting the pull-out strength of the formed asphalt layer.
[0035] Therefore, there is a need for a method that is simple to operate, low in cost, and can produce a road seal with superior pull-out strength.
[0036] In view of the above, the first aspect of this application provides a method for road sealing, the method comprising: S1, spraying foamed asphalt onto the road surface to form a foamed asphalt tack coat, wherein the foamed asphalt includes hot asphalt and emulsified asphalt; S2, spreading crushed stone onto the foamed asphalt tack coat to complete the road sealing.
[0037] In this application, foamed asphalt possesses a rich and stable foam structure. By foaming hot asphalt and emulsified asphalt to form foamed asphalt, the viscosity of the hot asphalt can be reduced, thus simplifying construction. Furthermore, foamed asphalt typically has a large volume expansion rate, not less than three times, enabling a unit volume of foamed asphalt to cover a larger ground area, thereby reducing the amount of asphalt spread and lowering paving costs. Simultaneously, the spread aggregate falls into the larger volume-expanding foamed asphalt, achieving a tighter coating and significantly improving the bond strength between the foamed asphalt tack coat and the aggregate. Moreover, the foamed asphalt in this application maintains stable air bubbles for a certain period, effectively extending its half-life. This allows sufficient time for the foamed asphalt to coat the aggregate, resulting in a longer operable time for aggregate spreading during construction, facilitating on-site control, and enabling better coating of the aggregate with the foamed asphalt tack coat. The resulting aggregate seal is less prone to material loss and has greater durability. Therefore, the road sealing method of this application is simple to operate, more economical, and conducive to large-scale road sealing construction.
[0038] The preparation method of foamed asphalt typically involves reacting liquid asphalt with water at high temperature. The rapid vaporization of water generates expansion force, causing the asphalt to form a large number of uniform bubble structures. This application uses emulsified asphalt and hot asphalt as raw materials to prepare foamed asphalt. Emulsified asphalt refers to viscous asphalt that, in the presence of a surfactant, is mechanically dispersed in water in a droplet state to form an oil-in-water (O / W) asphalt emulsion. In emulsified asphalt, the surfactant, water, and petroleum asphalt have already formed a stable, uniform, and continuous system, eliminating the need for further emulsification using high-shear milling equipment. Furthermore, emulsified asphalt is relatively inexpensive and readily available, thereby reducing equipment and material costs and increasing operational convenience. This application uses emulsified asphalt as a foaming precursor. During the foaming process, the water in the emulsified asphalt vaporizes upon contact with the high-temperature raw material asphalt, forming bubble cavities. Meanwhile, the petroleum asphalt in the emulsified asphalt is squeezed to the gas-liquid interface, aggregating and fusing with the raw material asphalt to form a stable asphalt film. Ultimately, the raw material asphalt foams and expands, forming a foam-like structure. Meanwhile, because the surfactant has formed a stable arrangement in the emulsified asphalt, it acts as a foam stabilizer during the foaming process, ensuring uniform foaming of the raw asphalt and resulting in a foamed asphalt composition with a greater expansion rate and a longer half-life. Furthermore, emulsified asphalt is often used as a tack coat and exhibits good adhesion to road surfaces. When emulsified asphalt is sprayed simultaneously with the high-temperature raw asphalt for foaming, even if it drips onto the ground, it will not form a water film that reduces the adhesion strength between the foamed asphalt composition and the ground. The good adhesion of the emulsified asphalt itself also reduces the problem of non-stickiness caused by wet or dusty surfaces, thus preventing the asphalt pavement from easily detaching.
[0039] In some embodiments, foamed asphalt is prepared by the following steps: spraying emulsified asphalt to obtain an emulsified asphalt fog curtain; spraying hot asphalt to obtain a hot asphalt fog curtain; mixing the emulsified asphalt fog curtain and the hot asphalt fog curtain to foam, thereby obtaining foamed asphalt. The above-mentioned emulsified asphalt and hard asphalt are mixed at a certain temperature to complete foaming and obtain foamed asphalt, wherein the temperature of the hot asphalt is 140-190°C and the temperature of the emulsified asphalt is 20-60°C.
[0040] When hot asphalt and emulsified asphalt at a certain temperature are mixed and foamed, the hot asphalt and emulsified asphalt in a fog-like state have a larger contact area. The water in the emulsified asphalt is vaporized more completely by the temperature of the hot asphalt, making it easier to generate bubbles, thus making the foaming effect of the hot asphalt better.
[0041] High temperatures weaken the intermolecular forces of hot asphalt, softening it and reducing its viscosity, thus increasing its rheological properties. Conversely, if the temperature of the hot asphalt is too low, the water in the emulsified asphalt cannot completely vaporize during foaming, leading to foaming difficulties and rapid cooling, resulting in increased viscosity and construction difficulty. Excessively high temperatures, on the other hand, easily cause the hot asphalt to age. Heating the hot asphalt to 140℃-190℃ provides a suitable viscosity for subsequent processing while avoiding excessively high temperatures that cause thermo-oxidative aging and difficulty in molding. Different types of hot asphalt require different softening temperatures, and those skilled in the art can select an appropriate temperature based on the type of hot asphalt used and the required viscosity (typically based on requirements that do not affect flow and spraying into a mist, such as a Bush rotation viscosity of less than 3 Pa·s). For example, the temperature of the hot asphalt can be 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or any value within a range therein. Heating emulsified asphalt improves its fluidity and reduces its viscosity, thus facilitating the dispersion of the asphalt into finer spray droplets. This allows for more complete foaming during the subsequent foaming process and enhances the stability of the foam structure within the foamed asphalt. Furthermore, a temperature difference is necessary between the hot asphalt and the emulsified asphalt used for foaming to ensure the water in the emulsified asphalt can vaporize. For the same type of hot asphalt, at the same temperature, a lower emulsified asphalt temperature and a larger temperature difference result in more vigorous foaming, potentially leading to explosive foaming. The volume expansion rate of the hot asphalt increases instantaneously, but its half-life is poor. Conversely, a higher emulsified asphalt temperature and a smaller temperature difference result in a gentler foaming process, with a slightly lower volume expansion rate of the hot asphalt, but a longer half-life. It is important to note that if the temperature of the emulsified asphalt exceeds 80°C, the surfactant will become ineffective, leading to demulsification. For example, the temperature of the emulsified asphalt can be any value within the range of 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, and the range thereof. In some alternative embodiments, the temperature of the emulsified asphalt is 20°C-40°C.
[0042] In some embodiments, the mass of emulsified asphalt in the foamed asphalt is 5%-15% of the mass of hot asphalt. The amount of emulsified asphalt is adjusted appropriately to achieve the desired foaming effect. If the viscosity of the hot asphalt used is high, the mass percentage of emulsified asphalt will be increased to prevent the bubbles from becoming too hard and causing breakage. If the formed bubbles are too large, the amount of emulsified asphalt can be reduced. Furthermore, the foaming effect is also affected by factors such as air temperature, hot asphalt temperature, solid content of the emulsified asphalt, and construction speed. The amount of emulsified asphalt can be controlled according to actual construction needs. The foaming conditions of this application are simple and easier to control in real time to meet construction requirements. For example, the amount of emulsified asphalt can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value within the range thereof.
[0043] In some embodiments, the hot asphalt includes a first petroleum asphalt, which is selected from one or more of 20# petroleum asphalt, 70# petroleum asphalt, 90# petroleum asphalt, and 110# petroleum asphalt. Among these, 20# petroleum asphalt, with a penetration of less than 30 dmm, is a relatively ideal non-stick asphalt material. Heating it and mixing it with emulsified asphalt to foam it yields foamed asphalt with superior foaming effect. Subsequent construction results in a smoother asphalt layer with better pull-out strength, without the need for a costly emulsification process. 70#, 90#, and 110# petroleum asphalts have lower viscosity and lower softening points, making them suitable for different types of road conditions. However, petroleum asphalts with lower viscosity and lower softening points, such as 70# and 90# petroleum asphalts, may experience delamination in asphalt layers constructed under the high temperatures of summer in my country, leading to problems such as road surface shoving, rubbing, and material shedding. Therefore, these petroleum asphalts can be modified to improve their high-temperature stability, enabling them to bond tightly to the road surface without peeling at high temperatures, and to have a lower penetration and be harder, making them less susceptible to being carried away by vehicle wheels. When subsequently spreading crushed stone, it exhibits superior adhesion to asphalt, resulting in a road seal layer that is less prone to material loss. Traffic can be opened immediately after construction without a curing period. In some embodiments, the hot asphalt includes modified asphalt, which comprises a modifier and a first petroleum asphalt. The modifier is selected from one or more of anti-rutting masterbatches, styrene-butadiene-styrene block copolymers, rubber powder, natural asphalt, coal liquefaction asphalt, and resins.
[0044] Anti-rutting masterbatch is a type of hard asphalt particle with near-zero penetration after oxidation treatment of petroleum asphalt. Anti-rutting masterbatch is typically used to improve the high-temperature stability of asphalt, reduce penetration, and obtain a non-stick asphalt bond layer. In some embodiments, anti-rutting masterbatch includes that from Luoyang Petrochemical. This product has low impurity content and good quality.
[0045] Styrene-butadiene-styrene block copolymer (SBS) is a thermoplastic elastomer formed by block copolymerization of styrene and butadiene. It is a commonly used polymer modifier in road engineering, and its core function is to balance the high-temperature stability and low-temperature crack resistance of asphalt.
[0046] Rubber powder can absorb the oil in asphalt, increase the viscosity of hot asphalt, and enable the asphalt to form a continuous elastic network structure, thereby improving the high-temperature stability and low-temperature crack resistance of asphalt. In some embodiments, the rubber powder is selected from one or more of waste tire rubber powder, styrene-butadiene rubber powder, natural rubber powder, nitrile rubber powder, and chloroprene rubber powder.
[0047] Natural asphalt is a mineral formed by the permeation of crude oil into the ground, its long-term evaporation, oxidation by oxygen in the air under sunlight, and subsequent polymerization. In some embodiments, the natural asphalt is selected from one or more of the following: Indonesian Buton rock asphalt, Trinidad Lake asphalt, Iranian rock asphalt, Albanian natural asphalt, and Sichuan Guangyuan rock asphalt. Using the aforementioned natural asphalt can increase the softening point of petroleum asphalt and its adhesion to aggregates, resulting in a foamed asphalt tack coat with superior tensile strength.
[0048] Resin is a class of thermoplastic high-molecular-weight organic compounds that, after melting upon heating, can be dispersed in asphalt, absorbing light oil components and improving the high-temperature deformation resistance of asphalt pavements. Using the aforementioned resin can increase the viscosity of petroleum asphalt, resulting in foamed asphalt with superior volume expansion rate and half-life, and achieving a more uniform asphalt layer with better pull-out strength. In some embodiments, the resin is selected from one or more of polyethylene resin, C9 resin, or C5 resin. These resins exhibit better compatibility with asphalt, which is beneficial for improving the softening point and adhesion of modified asphalt.
[0049] Coal liquefaction pitch is a byproduct of the coal liquefaction process. It has a high softening point, high hardness, and virtually zero penetration.
[0050] In some embodiments, emulsified asphalt, by mass fraction, comprises: 30%-50% second petroleum asphalt, 48%-70% water, and 0.5%-2% surfactant. Increasing the petroleum asphalt content in emulsified asphalt increases the difficulty of the emulsification process, thereby increasing production costs. Conversely, emulsified asphalt with a solids content below 50% has lower production costs; for example, commercially available conventional emulsified asphalt typically has a solids content of 50% (i.e., 50% asphalt content). Therefore, emulsified asphalt with a second petroleum asphalt content of around 50% is economically readily available and can reduce the production cost of foamed asphalt. Furthermore, the petroleum asphalt in emulsified asphalt provides it with a certain degree of viscosity, reducing surface wetness and the resulting lack of adhesion between the asphalt and the ground when dropped. Conversely, when the petroleum asphalt content is too low (e.g., below 30%), on the one hand, the viscosity of the emulsified asphalt decreases, and on the other hand, manufacturers may not mass-produce such low-solids-content emulsified asphalt due to economic reasons, leading to increased production costs. Therefore, by maintaining a petroleum asphalt content of 30%-50% in emulsified asphalt, it is beneficial to form stable emulsified asphalt and reduce usage costs. Furthermore, with a lower petroleum asphalt content, the water content in the emulsified asphalt increases accordingly. An appropriate water content facilitates the contact between the emulsified asphalt and hot asphalt at high temperatures, generating bubbles and resulting in foamed asphalt with a high expansion rate and long half-life. For example, the mass fraction of the third petroleum asphalt can be 30%, 35%, 40%, 45%, 50%, or any two of these values. For example, the mass fraction of water can be 48%, 50%, 55%, 60%, 65%, 70%, or any two of these values. Surfactants can improve the stability of asphalt bubbles formed by water vaporization by adjusting the surface tension, thereby increasing the half-life and expansion rate of the foamed asphalt. Reducing the amount of surfactant used can further reduce costs. Those skilled in the art can adjust the dosage according to the type of emulsifier and asphalt from different manufacturers to obtain stable emulsified asphalt. For example, the mass fraction of the surfactant can be 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, or a range of any two of these values.
[0051] In some embodiments, the second petroleum asphalt includes: 50# petroleum asphalt, 70# petroleum asphalt, 90# petroleum asphalt, or 110# petroleum asphalt. These asphalts have lower viscosity, are easier to emulsify, forming more dispersed and finer asphalt particles, and are more stable. When sprayed, they have a larger contact area with the hot asphalt, thus improving the foaming effect.
[0052] In some embodiments, the surfactant includes cationic surfactants, nonionic surfactants, or amphiphilic surfactants. These emulsifying surfactants possess an amphiphilic structure (hydrophilic and lipophilic), which reduces the interfacial tension of petroleum asphalt, allowing for uniform mixing of the petroleum asphalt and water to form a stable emulsion. Because the emulsified asphalt contains surface activity, the asphalt foam formed after the water in the emulsified asphalt expands upon contact with hot asphalt is more stable, improving the foaming effect of the resulting foamed asphalt. Furthermore, using emulsified asphalt for foaming is less costly and more economical.
[0053] In some embodiments, the volume expansion rate of the foamed asphalt is greater than or equal to 3 times. In some embodiments, the volume expansion rate of the foamed asphalt is 4-8 times. Here, the expansion rate refers to the ratio of the maximum volume of the asphalt at the moment of foaming to the volume of the original unfoamed asphalt. Using hot asphalt and emulsified asphalt, the foamed asphalt obtained by the construction method of this application has a better foaming effect, and can obtain foamed asphalt with a volume expansion rate in the above range. During construction and application, it can be more evenly spread on the road surface, and can also more firmly fix the crushed stone during subsequent application.
[0054] In some embodiments, the half-life of the foamed asphalt is greater than or equal to 6 seconds. In some embodiments, the half-life of the foamed asphalt is greater than or equal to 8 seconds. In some embodiments, the half-life of the foamed asphalt is 10-20 seconds. Here, half-life refers to the time (in seconds) it takes for the foamed asphalt to decay from its maximum volume to half its original volume. A longer half-life is advantageous for achieving a better aggregate seal when spreading aggregate.
[0055] In some implementations, the method further includes repeating steps S1 and S2 at least once. The pavement structure combination of foamed asphalt tack coat and chip seal can be repeatedly laid, often referred to as the "layer paving method." This means that the pavement is laid with only one layer of foamed asphalt tack coat and one layer of chip seal, or, based on one layer of foamed asphalt tack coat and one layer of chip seal, at least one additional layer of "foamed asphalt tack coat and one layer of chip seal" is laid. Whether to repeat the paving or the number of repetitions can be chosen according to actual application needs. For example, if it is necessary to increase the pavement thickness, laying one or more layers of the "foamed asphalt tack coat and chip seal" pavement structure can extend the service life of the pavement. However, additional paving will increase construction costs, and the decision to repeat the paving should be based on project requirements and costs. It is important to emphasize that when using the "layer paving method" for pavement construction, in order to achieve interlocking between the chips and obtain a smooth pavement layer, the particle size of the chips in the previous layer is usually smaller than that of the chips in the layer below it.
[0056] In some embodiments, step S2 includes: spreading crushed stone onto the foamed asphalt tack coat after the foamed asphalt has expanded to its maximum volume, thus completing the road seal. To achieve a tighter coating of the crushed stone, it is possible to spread the crushed stone after the foamed asphalt has expanded to its maximum volume. Furthermore, since the foamed asphalt obtained through this application has a long half-life, spreading it after it has expanded to its maximum volume will not cause a shortage of construction time for spreading the crushed stone.
[0057] In some implementations, the application rate of foamed asphalt per layer is 1.2-2.5 kg / m³. 2 Optionally, the application rate of foamed asphalt per layer is 1.5-2.2 kg / m³. 2 When applying foamed asphalt, the application rate needs to be adjusted according to the type of aggregate, the viscosity of the foamed asphalt, the construction conditions, and the actual road surface. More asphalt is not necessarily better; excessive application can lead to oil seepage, shoving, and decreased skid resistance, while insufficient application can cause loosening and peeling.
[0058] In some implementations, the aggregate particle size range is selected from any of the following: 3-5 mm, 5-8 mm, 7-11 mm, and 10-15 mm. Different aggregate sizes can be selected for sealing depending on the road application requirements. Aggregates with a particle size range of 3-5 mm are suitable for ultra-thin, fine road sealing, primarily for waterproofing and preventative maintenance. Aggregates with a particle size range of 5-8 mm are used for general-purpose sealing, resulting in a seal with balanced waterproofing, skid resistance, and smoothness. Aggregates with a particle size range of 7-11 mm are mainly used to prepare skid-resistant aggregate seals, focusing on improving the road surface's skid resistance and repairing surface wear. Aggregates with a particle size range of 10-15 mm are suitable for thick, heavy-duty road sealing, resulting in structural reinforcement, base layer sealing, or heavy-duty roads.
[0059] If the aggregate size is too large, there will be problems such as insufficient asphalt coating, uneven seal layer thickness, and poor flatness; if the aggregate size is too small, the specific surface area will be large, making it prone to oil seepage and slipping; the pores will be small, making it difficult for water vapor to escape, which will easily lead to road surface bulges; and if there is more fine material, the wear resistance and crack resistance will be poor.
[0060] In some implementations, the coverage rate of the crushed stone is 95%-100%. This coverage rate refers to the percentage of the asphalt layer area covered by crushed stone. Maintaining an appropriate coverage rate results in a road seal with superior smoothness, strong stability, and good anti-skid properties and smoothness. If the coverage rate is too low, the asphalt layer will be exposed, leaving less protection and resulting in an uneven, potholed road surface. If the coverage rate is too high, there will be more loose stones not fixed by the asphalt, which will affect driving safety and road surface smoothness.
[0061] A second aspect of this application provides a road sealing device, such as Figure 1 As shown, the road sealing device includes: a work vehicle, an asphalt spraying system, and a gravel spreading system, with the asphalt spraying system and the gravel spreading system mounted on the work vehicle; wherein, the asphalt spraying system is used to spray foamed asphalt to form a foamed asphalt tack coat, and the gravel spreading system is used to spread gravel on the foamed asphalt tack coat.
[0062] In some embodiments, the asphalt spraying system includes a hot asphalt storage tank and a hot asphalt spraying device connected to the hot asphalt storage tank, an emulsified asphalt storage tank and an emulsified asphalt spraying device connected to the emulsified asphalt storage tank; the hot asphalt spraying device is used to spray hot asphalt, the emulsified asphalt spraying device is used to spray emulsified asphalt, and the sprayed hot asphalt and the sprayed emulsified asphalt come into contact before falling to the ground.
[0063] In some embodiments, the emulsified asphalt spraying device is located in front of the hot asphalt along the vehicle's direction of travel, and the spraying directions of both the hot asphalt spraying device and the emulsified asphalt spraying device are directed towards the rear along the vehicle's direction of travel. Along the vehicle's direction of travel, the hot asphalt spraying device and the emulsified asphalt spraying device spray hot asphalt and emulsified asphalt respectively backwards, and the hot asphalt and emulsified asphalt come into contact before falling to the ground to achieve foaming, thereby obtaining foamed asphalt that falls to the ground. By positioning the emulsified asphalt spraying device in front of the hot asphalt along the vehicle's direction of travel, the emulsified asphalt is sprayed out before the hot asphalt, allowing the resulting emulsified asphalt mist to fully contact the hot asphalt mist, thus achieving sufficient foaming and improving the stability of the foamed asphalt. Furthermore, this positioning also prevents the hot asphalt from clogging the emulsified asphalt atomizing nozzles, and the emulsified asphalt falling to the ground before the hot asphalt prevents the road surface from becoming wet, thus affecting the adhesion between the foamed asphalt and the road surface.
[0064] In some embodiments, the hot asphalt spraying device has a hot asphalt spraying bar laterally arranged behind the vehicle's direction of travel, and the hot asphalt spraying bar has at least one spaced nozzle, which is an atomizing nozzle; the emulsified asphalt spraying device has an emulsified asphalt spraying bar laterally arranged behind the vehicle's direction of travel, and the emulsified asphalt spraying bar has at least one spaced nozzle, which is an atomizing nozzle. The number of atomizing nozzles on the hot asphalt spraying device and the emulsified asphalt spraying device can be increased or decreased according to actual conditions to improve the asphalt layer spraying efficiency. In some embodiments, the nozzle spacing is 120-150mm, and the nozzle orifice diameter is selected from 2mm, 3mm, 4mm, and 5mm.
[0065] In some implementations, the hot asphalt spraying boom and the emulsified asphalt spraying boom are arranged parallel to each other. The spraying direction and spraying pressure of the nozzles on the hot asphalt spraying boom and the emulsified asphalt spraying boom can be adjusted according to construction requirements, so that the hot asphalt spray and the emulsified asphalt spray can cross-contact in the air before contacting the road surface, fully mix, and foam. For example, the spraying directions of the nozzles on the hot asphalt spraying boom and the emulsified asphalt spraying boom are at an angle, so that the sprayed emulsified asphalt mist can merge with the sprayed hot asphalt mist, and the emulsified asphalt can be completely coated by the hot asphalt, which rapidly evaporates the large amount of water in the emulsified asphalt, resulting in foamed asphalt with better foaming effect.
[0066] In some implementations, the gravel spreading system is located behind the hot asphalt spraying device and the emulsified asphalt spraying device along the direction of vehicle travel.
[0067] In some embodiments, the aggregate spreading system includes an aggregate storage device, a belt conveyor, a spiral spreader, spreading rollers, a material gate, and a control system. The aggregate is conveyed from the aggregate storage device to the spiral spreader via the belt conveyor, where it is spread laterally. The spreading rollers then spread the aggregate through the material gate. During this process, the control system automatically adjusts the speed of the spreading rollers and the opening of the material gate according to changes in vehicle speed to ensure precise and uniform spreading of the aggregate across the entire width of the asphalt tack coat.
[0068] In some embodiments, the road seal device further includes a temperature control system for maintaining the temperature of the asphalt spraying system. The preparation of foamed asphalt requires both the hot asphalt and emulsified asphalt to have a certain temperature. During construction, to stabilize the foaming effect, the aforementioned temperature control system is needed to stabilize the asphalt temperature, thereby further stabilizing the foaming state of the foamed asphalt.
[0069] In some embodiments, the road seal device further includes a high-pressure pump and a flow meter, each independently installed between each material storage tank and the corresponding material spraying chamber, for monitoring and regulating the amount of material sprayed, facilitating adjustments during construction.
[0070] Example In this application, the CK-60 cationic fast-cracking emulsifier is from Luohe Tianlong Chemical Co., Ltd., the 20# petroleum asphalt is from Jiangsu Tiannuo Road Materials Technology Co., Ltd., the desulfurized rubber powder is from Hubei Hairui Rubber Co., Ltd., the natural asphalt NNB20 is from Xi'an Zhongli Asphalt Co., Ltd., the foaming agent is from Longfu Tailu, the Jingbo 70# petroleum asphalt is from Shandong Jingbo Petrochemical Co., Ltd., the Qilu 70# petroleum asphalt is from Qilu Branch of China Petroleum & Chemical Corporation, the anti-rutting masterbatch is from Luoyang Branch of China Petroleum & Chemical Corporation, and the fast-cracking SBS modified emulsified asphalt is from Xi'an Guolin Industrial Co., Ltd. The medium-cracking emulsifier PION S331 is from Shandong Paini Road & Bridge Materials Co., Ltd., and the foaming asphalt half-life delay additive is from Beijing Tailu Technology.
[0071] This application embodiment utilizes a mobile asphalt foaming device for applying foamed asphalt non-stick tack coat. The mobile asphalt foaming device includes a work vehicle, an asphalt spraying system, and a gravel spreading system, both mounted on the work vehicle.
[0072] The asphalt spraying system includes a hot asphalt storage tank and a hot asphalt spraying device connected to the hot asphalt storage tank, an emulsified asphalt storage tank and an emulsified asphalt spraying device connected to the emulsified asphalt storage tank. The emulsified asphalt spraying device is located ahead of the hot asphalt spraying device in the direction of vehicle travel, that is, the emulsified asphalt spraying device is located further forward in the direction of vehicle travel than the hot asphalt spraying device.
[0073] The hot asphalt spraying device has a horizontally mounted hot asphalt spraying bar at its rear, away from the direction of travel of the working vehicle. The hot asphalt spraying bar has spaced-atomizing nozzles. Similarly, the emulsified asphalt spraying device has a horizontally mounted emulsified asphalt spraying bar at its rear, also away from the direction of travel of the working vehicle. The emulsified asphalt and hard asphalt are arranged parallel to each other. The nozzles on the hot asphalt and emulsified asphalt spraying bars are angled relative to the horizontal road surface, allowing the sprayed emulsified asphalt and hard asphalt to come into contact at a certain angle, fully mixing and foaming. The foamed asphalt then settles evenly onto the road surface.
[0074] The gravel spreading system is located behind the hot asphalt spraying device and the emulsified asphalt spraying device along the direction of vehicle travel.
[0075] The aggregate spreading system includes an aggregate storage device, a belt conveyor, a spiral distributor, spreading rollers, a material gate, and a control system. The aggregate is conveyed from the storage device to the spiral distributor via the belt conveyor, where it is spread laterally. The spreading rollers then distribute the aggregate through the material gate. During this process, the control system automatically adjusts the speed of the spreading rollers and the opening of the material gate according to changes in vehicle speed to ensure precise and uniform spreading of the aggregate across the entire width of the asphalt tack coat.
[0076] The components and property parameters of the hot asphalt used in the embodiments and comparative examples of this application are shown in Table 1. The hot asphalt can be prepared by methods known in the art or obtained commercially. The penetration is tested according to the penetration test method T0604-2011 of the Ministry of Transport industry standard "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" JTG 3410-2025. The softening point is tested according to the softening point test method T0606-2011 of the Ministry of Transport industry standard "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" JTG 3410-2025.
[0077] Example 1 The method for applying the road seal layer in this embodiment is as follows: The hot asphalt used in this embodiment is micronized natural asphalt NNB20 with a penetration of 17 dmm and a softening point of 72℃. The emulsified asphalt used in this embodiment (at a temperature of 25℃) is PC-3 emulsified asphalt with a solid content of 30% (the base asphalt is Qilu 70# petroleum asphalt, and the emulsifier is CK-60 cationic fast-cracking emulsifier from Luohe Tianlong Chemical Co., Ltd., with an emulsifier dosage of 0.5%).
[0078] Using the aforementioned portable asphalt foaming device, hot asphalt and emulsified asphalt are placed in their respective storage tanks using 4mm diameter atomizing nozzles. They are then sprayed from their respective nozzles via spray bars, allowing the hot and emulsified asphalt to contact each other in the air and complete the foaming process. The spraying temperature of the hot asphalt is 180℃, and the spraying temperature of the emulsified asphalt is room temperature (25℃). The resulting foamed asphalt falls to the ground, forming a foamed asphalt tack coat. The mass ratio of hot asphalt to emulsified asphalt is 100:10. When the foamed asphalt reaches its maximum volume (denoted as 0s, i.e., after the foamed asphalt reaches its maximum volume in 0s), crushed stone is simultaneously spread to obtain a crushed stone seal coat. The particle size range of the spread crushed stone is 7-11mm, and the crushed stone coverage rate is 95%.
[0079] Example 2 The only difference between this embodiment and Embodiment 1 is the timing of the gravel spreading; all other conditions are the same. Specifically, the gravel spreading time is 10 seconds, meaning that the gravel is spread 10 seconds after the foamed asphalt has expanded to its maximum volume, in order to obtain a gravel seal layer.
[0080] Example 3 The only difference between this embodiment and Embodiment 1 is the timing of the aggregate spreading; all other conditions are the same. Specifically, the aggregate spreading time is 20 seconds, meaning that the aggregate is spread 20 seconds after the foamed asphalt has expanded to its maximum volume, in order to obtain the aggregate seal layer.
[0081] Example 4 The only difference between this embodiment and Embodiment 1 is the timing of the aggregate spreading; all other conditions are the same. Specifically, the aggregate spreading time is 30 seconds, meaning that the aggregate is spread 30 seconds after the foamed asphalt has expanded to its maximum volume, in order to obtain the aggregate seal layer.
[0082] Example 5 On the gravel seal layer obtained in Example 1, a second layer of foamed asphalt tack coat was applied using the same materials and methods (as shown in Table 2), except that the particle size range of the gravel and the application rate of the second layer of hot asphalt were changed. The particle size range of the gravel was 5-8 mm, and the application rate of the second layer of hot asphalt was 1.5 kg / m³. 2 The resulting second gravel seal layer had a gravel coverage of 100%.
[0083] Example 6 Prepared using a method similar to that in Example 1, except that the type of hot asphalt, the mass ratio of hot asphalt to emulsified asphalt, the temperature of the hot asphalt, and the amount of hot asphalt spread were adjusted according to the parameters shown in Table 2.
[0084] Example 7 Prepared using a method similar to that of Example 6, except that the application rate of hot asphalt in this example is 2 kg / m³. 2 .
[0085] Example 8 The asphalt was prepared using a method similar to that of Example 6, except that the application rate of the hot asphalt in this example was 2.5 kg / m³. 2 .
[0086] Example 9 The process was similar to that in Example 1, except that the type of hot asphalt, the type of emulsified asphalt, the mass ratio of hot asphalt to emulsified asphalt, the temperature of the hot asphalt, and the application rate of the hot asphalt were adjusted according to the parameters shown in Table 2. The hot asphalt was 20# petroleum asphalt. The emulsified asphalt used in this example consisted of 50% 70# petroleum asphalt, 2% cationic medium-cracking emulsifier PION S331, and 48% water. The mass ratio of hot asphalt to emulsified asphalt was 100:15, and the application rate of the hot asphalt on the road surface was 1.5 kg / m². 2 .
[0087] Example 10 The process was similar to that in Example 1, except that the types of hot asphalt, emulsified asphalt, the mass ratio of hot asphalt to emulsified asphalt, the temperature of the hot asphalt, and the application rate of the hot asphalt were adjusted according to the parameters shown in Table 2. In this example, the hot asphalt used included 80 wt% Qilu 70# petroleum asphalt and 20% desulfurized rubber powder. The emulsified asphalt used in this example (at a temperature of 40°C) was PC-3 emulsified asphalt with a solid content of 40% (the base asphalt was Qilu 70#), and the emulsifier was 2% cationic medium-cracked PION S331. The mass percentage of hot asphalt to emulsified asphalt was 100:10, and the application rate of the hot asphalt in this example was 2.0 kg / m³. 2 .
[0088] Comparative Example 1 This comparative example uses NNB20 and water for foaming, with a mass ratio of NNB20 to water of 100:5.
[0089] The construction method for this comparative example is as follows: The water stored in the water tank of the aforementioned portable asphalt foaming device is atomized under high pressure by a high-pressure pump and sprayed out through at least one atomizing nozzle of the water spray pipe to form a water fan-shaped fog curtain.
[0090] Then, the hot asphalt stored in the hot asphalt storage tank of the aforementioned portable asphalt foaming device is atomized under high pressure by a high-pressure pump and sprayed out through at least one atomizing nozzle of the hot asphalt spraying pipe to form a hot asphalt fan-shaped fog curtain.
[0091] A water-sprayed fan-shaped mist is first sprayed out, and then fully blends and foams with the hot asphalt fan-shaped mist that forms subsequently, resulting in foamed asphalt.
[0092] The resulting foamed asphalt falls to the ground, forming a foamed asphalt tack coat. Once the foamed asphalt has expanded to its maximum volume (recorded as 0 seconds after the aggregate spreading time), 7-11mm aggregate is simultaneously spread to obtain a aggregate seal coat. The application rate of hot asphalt is 2 kg / m². 2 The coverage rate of gravel is 95%.
[0093] Comparative Example 2 This comparative example utilizes NNB20 containing a foaming agent and water for foaming, with a mass ratio of NNB20 containing the foaming agent to water of 100:5. The NNB20 containing the foaming agent comprises NNB20 and a foaming asphalt half-life delaying agent (foaming agent), with a mass ratio of NNB20 to the foaming asphalt half-life delaying agent of 1000:5.
[0094] The construction method for this comparative example is as follows: The water stored in the water tank of the aforementioned portable asphalt foaming device is atomized under high pressure by a high-pressure pump and sprayed out through at least one atomizing nozzle of the water spray pipe to form a water fan-shaped fog curtain.
[0095] Then, the hot asphalt (including foaming agent NNB20) stored in the hot asphalt storage tank of the aforementioned mobile asphalt foaming device is atomized under high pressure by a high-pressure pump and sprayed out through at least one atomizing nozzle of the hot asphalt spraying pipe to form a hot asphalt fan-shaped fog curtain.
[0096] A water-sprayed fan-shaped mist is first sprayed out, and then fully blends and foams with the hot asphalt fan-shaped mist that forms subsequently, resulting in foamed asphalt.
[0097] The resulting foamed asphalt falls to the ground, forming a foamed asphalt tack coat. When the foamed asphalt expands to its maximum volume (denoted as 0 seconds after the aggregate is spread), aggregate is simultaneously spread to obtain a aggregate seal coat. The application rate of hot asphalt is 2 kg / m². 2 The coverage rate of gravel is 95%.
[0098] Comparative Example 3 This comparative example directly utilizes the hot asphalt from Example 1, without emulsified asphalt, to spray the asphalt layer, forming an asphalt tack coat. Subsequently, crushed stone is simultaneously sprayed to obtain a crushed stone seal coat. Specifically, in this comparative example, the emulsified asphalt nozzle in the portable asphalt foaming device is turned off during asphalt spraying. All other steps, methods, and parameters are the same as in Example 1.
[0099] Comparative Example 4 This comparative example uses only the rubber-modified asphalt from Example 10 as the hot asphalt, without emulsified asphalt, to spray the asphalt layer, forming an asphalt tack coat. Subsequently, crushed stone is simultaneously sprayed to obtain a crushed stone seal coat. Specifically, in this comparative example, the emulsified asphalt nozzle in the portable asphalt foaming device is turned off during asphalt spraying. All other steps, methods, and parameters are the same as in Example 5.
[0100] Comparative Example 5 This comparative example uses only hot asphalt for the application of the asphalt layer, without emulsified asphalt, to form an asphalt tack coat. The hot asphalt used is Jingbo 70# petroleum asphalt. Subsequently, crushed stone is simultaneously applied to obtain a crushed stone seal. Specifically, in this comparative example, the emulsified asphalt nozzle in the portable asphalt foaming device is turned off during asphalt application. All other steps, methods, and parameters are the same as in Example 1.
[0101] Comparative Example 6 This comparative example uses only emulsified asphalt for the asphalt layer application, without hot asphalt to form an asphalt tack coat. The emulsified asphalt used is a fast-setting SBS modified emulsified asphalt. Subsequently, 7-11mm crushed stone is simultaneously applied to obtain a crushed stone seal. Specifically, in this comparative example, the hot asphalt nozzles in the portable asphalt foaming device are turned off during asphalt application. The emulsified asphalt temperature during application is 60℃, and the application rate is 1.2 kg / m³. 2 .
[0102] The penetration and softening point data of the hot asphalt in each embodiment are shown in Table 1.
[0103] The specific data for the type and dosage of hot asphalt, the composition and dosage of emulsified asphalt, the mass ratio of hot asphalt to emulsified asphalt, and the application methods for road seal (hot asphalt application temperature, hot asphalt application amount, and aggregate application time) in each embodiment are shown in Table 2.
[0104] Table 1 Physicochemical properties of hot asphalt
[0105] Table 2. Parameter data for road seal layer application
[0106] Testing experiment: To test the foaming effect, a portion of foamed asphalt was collected and stored in a container to test the expansion rate and half-life of the foamed asphalt in Examples 1-4, 6, 9-10 and Comparative Examples 1-2. The specific test results are shown in Table 3.
[0107] 1. Expansion rate test: Place a marked measuring rod in the test bucket, measure the original asphalt height and the height of the foamed asphalt when it expands to its highest point, and calculate the expansion rate by using the ratio.
[0108] 2. Half-life detection: The time required from the expansion of foamed asphalt to its maximum volume until it is reduced to half its original volume, measured in seconds.
[0109] The relevant effect parameters of the sealing layers formed in Examples 1-10 and Comparative Examples 1-6 were tested. The specific test results are shown in Table 3, and the test methods are as follows.
[0110] 3. Testing the uniformity of spraying: After the foamed asphalt is sprayed onto the ground, observe the uniformity of spraying, that is, whether it can continuously cover the ground.
[0111] 4. Testing the adhesion effect: After the foamed asphalt has been sprayed and the adhesive layer has been formed for five minutes, drive the construction vehicle back onto the road and visually observe whether the adhesive layer will be adhered to and carried away by the wheels.
[0112] 5. Pull-out strength test: Place the rutted plate specimen on the spraying equipment's travel path, and after the asphalt tack coat is formed, use a pull-out adhesion tester (BJZJ-FZL-W / Tianjin Tianchen Weiye Technology) to press a clean pull-out head onto the formed asphalt tack coat and measure the pull-out force at 25℃.
[0113] The rutted surface specimen is a 300*300*50mm AC-20 mixture rutted surface specimen formed by wheel rolling. A 1-2 cm layer is cut off to obtain a smooth surface layer, which serves as the substrate for the pull-out test, reducing the influence of different substrate friction coefficients and interface materials on the pull-out test. The rutted surface is placed on the path of the foamed asphalt spraying equipment, allowing the foamed asphalt (or the hot asphalt / emulsified asphalt in Comparative Examples 3-6) to fall onto the rutted surface.
[0114] For asphalt tack coats formed solely by spraying emulsified asphalt, the test plate with the asphalt tack coat needs to be placed in an oven to break the emulsion of the asphalt tack coat, allow the solidified moisture to evaporate, and then use a pull-off adhesion tester (BJZJ-FZL-W / Tianjin Tianchen Weiye Technology) for subsequent testing.
[0115] 6. Test of aggregate loss rate of chip seal: Refer to the test of aggregate retention rate of chip seal in T0771-2025 of JTG 3410-2025 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering".
[0116] Using a square hot-rolled steel plate with sides of 200mm and a thickness of 6mm, asphalt (foamed asphalt or hot asphalt / emulsified asphalt as in Comparative Examples 3-6) is sprayed onto the plate. After an asphalt layer forms on the plate, the mass of the asphalt layer is measured (mass of the plate after spraying M_adhesive - mass of the plate before spraying M_plate). After spreading the crushed stone, the plate is left to stand for 30 minutes until the plate temperature drops to room temperature. Then, the plate is inverted on a support so that the crushed stone sealing layer is facing down. Any loose crushed stone will fall off naturally. The mass of the plate is measured again, M1, and the mass of the bonded crushed stone, M2, is calculated (M1 - M_adhesive). Subsequently, following the method in T0771, a steel ball is dropped vertically and freely, impacting the center of the test plate within ±15mm. Any loose crushed stone will detach from the adhesive layer and fall off. After three consecutive impacts within 10 seconds, the plate mass M3 is weighed again, and the mass of the detached crushed stone (M3-M1) and the crushed stone loss rate (M3-M1) / M2 are calculated. This test result can indicate the degree of adhesion of the crushed stone to the asphalt layer.
[0117] In addition, for the asphalt layer in Comparative Example 6 containing only emulsified asphalt, the chip loss rate of the chip seal layer needs to be tested by first placing the test plate in an oven at 60°C for 24 hours to break the emulsified asphalt tack coat, allowing the solidified water to evaporate, and then weighing it and recording it as M tack coat, before proceeding with the subsequent tests and calculations.
[0118] Table 3. Indicators for Foamed Asphalt Tack Coat and Synchronous Chip Seal
[0119] In the table, " / " indicates that the data was not detected.
[0120] As can be seen from Examples 1-4, when the foamed asphalt was spread with crushed stone at 0 seconds, 10 seconds, 20 seconds, and 30 seconds after it expanded to its maximum volume, the later the spreading time, the smaller the volume of the foamed asphalt, and therefore the smaller the area of the crushed stone that could be coated by the foamed asphalt. Furthermore, the mass loss rate of the crushed stone gradually increased as the spreading time was delayed, indicating that completing the spreading of crushed stone within the half-life of the foamed asphalt yielded the best results.
[0121] Example 5 shows that because a two-layer road seal was applied, the second layer of crushed stone on the surface can be more tightly bonded to the next layer of crushed stone, resulting in a lower crushed stone mass loss rate.
[0122] In Examples 6-8, only the application rate of hot asphalt differed, and it can be seen that the aggregate mass loss rate decreased with increasing hot asphalt application rate. When the hot asphalt application rate reached 2.5 kg / m³... 2 At this point, the mass loss rate of crushed stone is even 0. It can be seen that due to the increase in the amount of hot asphalt, the volume of foamed asphalt that can be formed is larger, which in turn greatly increases the area that can be coated on the crushed stone, improving the tightness between the crushed stone and the foamed asphalt. This indicates that when the amount of hot asphalt used for foaming reaches a certain value, the mass loss rate of crushed stone can be greatly reduced.
[0123] Furthermore, Examples 9-10, which utilized different types of hot asphalt, were able to foam with emulsified asphalt to obtain an asphalt layer with superior tensile strength, and also showed good coating effect with crushed stone, resulting in a low loss rate of crushed stone quality.
[0124] The pull-out strength of Comparative Examples 1 and 2 was lower than that of Examples 1 and 3, mainly because water falling to the ground affected the interlayer bonding effect. In addition, their foaming effect was poor, the coating effect on the crushed stone was poor, and the loss rate of crushed stone quality was high.
[0125] Comparative Examples 3 and 4 both used only hot asphalt for road sealing. Due to its high viscosity, it was difficult to spread evenly. Although Comparative Examples 3 and 4 had good pull-out strength, their coating effect on crushed stone was poor. Comparative Example 5, which used unmodified hot asphalt, had poor pull-out strength and poor adhesion to crushed stone.
[0126] Comparative Example 6 uses only emulsified asphalt to prepare the asphalt layer. Since no road maintenance period was reserved for demulsification and dehydration, the chip seal layer was directly applied. The coating effect on the chip was poor, and the pull-out effect between the asphalt layer and the ground was also average.
[0127] The comparative examples above, which utilize only hot asphalt or emulsified asphalt for synchronous chip seal, demonstrate that using only hot asphalt or emulsified asphalt for the asphalt layer cannot meet the construction requirements for synchronous chip seal. Furthermore, this application shows that it can meet the construction requirements for efficient synchronous chip seal with relatively simple construction operations. This not only saves construction time and reduces construction costs, but also yields a pavement seal that is less prone to material loss and has superior pull-out strength.
[0128] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, and improvements made within the spirit and scope of this application are included within the scope of protection of this application.
Claims
1. A method for road surface sealing, characterized in that, The method includes: S1, Spray foamed asphalt onto the road surface to form a foamed asphalt tack coat, wherein the foamed asphalt includes hot asphalt and emulsified asphalt; S2, Spread crushed stone onto the foamed asphalt tack coat to complete the road seal.
2. The method according to claim 1, characterized in that, In the foamed asphalt, the mass of the emulsified asphalt is 5%-15% of the mass of the hot asphalt.
3. The method according to claim 1 or 2, characterized in that, The foamed asphalt is prepared through the following steps: The emulsified asphalt is sprayed to obtain an emulsified asphalt mist. The hot asphalt is sprayed to obtain a hot asphalt fog curtain; The emulsified asphalt fog curtain is mixed with the hot asphalt fog curtain to foam it, thereby obtaining the foamed asphalt. Wherein, the temperature of the hot asphalt is 140-190℃; and / or The temperature of the emulsified asphalt is 20-60℃.
4. The method according to any one of claims 1-3, characterized in that, The method further includes repeating step S1 and step S2 at least once.
5. The method according to any one of claims 1-4, characterized in that, Step S2 includes: after the foamed asphalt expands to its maximum volume, spreading crushed stone onto the foamed asphalt tack coat to complete the road seal.
6. The method according to any one of claims 1-5, characterized in that, The hot asphalt comprises either a first petroleum asphalt or a modified petroleum asphalt, wherein the modified petroleum asphalt comprises a modifier and the first petroleum asphalt, wherein... The modifier is selected from one or more of the following: anti-rutting masterbatch, styrene-butadiene-styrene block copolymer, rubber powder, natural asphalt, coal liquefaction pitch, and resin; and / or The first petroleum asphalt is selected from one or more of 20# petroleum asphalt, 70# petroleum asphalt, 90# petroleum asphalt and 110# petroleum asphalt.
7. The method according to any one of claims 1-6, characterized in that, By mass fraction, the emulsified asphalt comprises: 30%-50% second petroleum asphalt, 48%-70% water, and 0.5%-2% surfactant; wherein, The second type of petroleum asphalt includes: 50# petroleum asphalt, 70# petroleum asphalt, 90# petroleum asphalt or 110# petroleum asphalt.
8. The method according to claim 7, characterized in that, The surfactants include: cationic surfactants, nonionic surfactants, or amphiphilic surfactants.
9. The method according to any one of claims 1-8, characterized in that, The application rate of the foamed asphalt is 1.2-2.5 kg / m³. 2 The preferred value is 1.5-2.2 kg / m³. 2 .
10. The method according to any one of claims 1-9, characterized in that, The particle size range of the crushed stone is selected from any of the following: 3-5mm, 5-8mm, 7-11mm and 10-15mm; and / or The coverage of the crushed stone is 95%-100%.
11. The method according to any one of claims 1-10, characterized in that, The volume expansion rate of the foamed asphalt is greater than or equal to 3 times, preferably greater than or equal to 6 times.
12. The method according to any one of claims 1-11, characterized in that, The half-life of the foamed asphalt is greater than or equal to 6 seconds, preferably greater than or equal to 8 seconds.
13. A road sealing device, characterized in that, The road sealing device includes: a work vehicle, an asphalt spraying system, and a gravel spreading system, wherein the asphalt spraying system and the gravel spreading system are mounted on the work vehicle; wherein, the asphalt spraying system is used to spray foamed asphalt to form a foamed asphalt tack coat, and the gravel spreading system is used to spread gravel on the foamed asphalt tack coat.
14. The apparatus according to claim 13, characterized in that, The asphalt spraying system includes a hot asphalt storage tank and a hot asphalt spraying device connected to the hot asphalt storage tank, an emulsified asphalt storage tank and an emulsified asphalt spraying device connected to the emulsified asphalt storage tank; The hot asphalt spraying device is used to spray hot asphalt, and the emulsified asphalt spraying device is used to spray emulsified asphalt, wherein the sprayed hot asphalt and the sprayed emulsified asphalt come into contact before falling to the ground.
15. The apparatus according to claim 14, characterized in that, The emulsified asphalt spraying device is located in front of the hot asphalt along the direction of travel of the vehicle, and the spraying direction of the hot asphalt spraying device and the spraying direction of the emulsified asphalt spraying device are directed towards the rear along the direction of travel of the working vehicle.
16. The apparatus according to any one of claims 13-15, characterized in that, The road sealing device also includes a temperature control system for maintaining the temperature of the asphalt spraying system.