Method and system for rapidly measuring asphalt content in asphalt mixture

Abstract

The invention provides a method and a system for rapidly determining the content of asphalt in an asphalt mixture, and relates to the technical field of detection of the content of the asphalt in the asphalt mixture. The method comprises the following steps: firstly, immersing a crushed asphalt mixture into a first solution at the temperature of-25 DEG C to-30 DEG C, and keeping for 15-20 minutes at a constant temperature to embrittle the asphalt mixture; the first solution is a calcium chloride-ethylene glycol solution; then continuously vibrating the material subjected to low-temperature embrittlement at the frequency of 15-20 kHz so as to peel off the asphalt mixture; standing to separate floating layer asphalt and sinking stones; and collecting the stones, drying to constant weight, and calculating the mass percentage content of asphalt in the asphalt mixture. The measuring system comprises a low-temperature constant-temperature box body, a high-frequency vibration unit, a solution circulating module and a standing and collecting unit. The method can conveniently and rapidly test the asphalt content of the asphalt pavement material sample, has the advantages of greenness, no toxicity, environmental protection, high efficiency and recoverability of the sample, and is suitable for asphalt mixture production quality control and road engineering field detection.

Description

Technical Field

[0001] This invention relates to the field of asphalt content detection technology for asphalt materials used in road engineering, and specifically to a rapid method and system for determining the asphalt content in asphalt mixtures. Background Technology

[0002] In road engineering, the asphalt content in the asphalt pavement mixture directly affects the road performance of the asphalt pavement. Too low a content leads to insufficient bonding between aggregates, causing the pavement to become loose and peel off; too high a content easily results in bleeding, rutting, and other defects. Therefore, accurately determining the asphalt content is crucial for ensuring road quality. Rapid and accurate testing methods have significant engineering application value for achieving dynamic quality monitoring during construction, timely optimization of mix design, and reducing the risk of rework.

[0003] Currently, the main methods for determining the asphalt content in asphalt mixtures include extraction separation, combustion, and some microscopic methods. Among them: (1) The principle of extraction separation is to dissolve asphalt in an organic solvent, then separate the aggregate from the solvent-asphalt solution using a centrifuge or filtration device, and finally calculate the content based on the mass difference. The specific steps include sample preparation, solvent soaking, centrifugation or filtration, drying and weighing. For example, Chinese patent document CN212059607U discloses a weighable side-filter asphalt mixture extractor, which uses the above principle to determine the asphalt content in the mixture. (2) The principle of combustion is to burn asphalt at high temperature to completely oxidize and decompose it into CO2 and H2O. After the residual aggregate is cooled, it is weighed, and the asphalt content is calculated based on the mass difference. The steps include weighing, high-temperature combustion, cooling and weighing. For example, Chinese patent document CN2447782Y discloses a combustion method asphalt content measuring instrument. The corresponding measurement method is to use this principle to put the asphalt mixture into the high-temperature combustion chamber of the measuring instrument for combustion. The combustion asphalt smoke is filtered and then discharged. The weight lost by asphalt combustion is weighed with a balance, and then the percentage content of asphalt is calculated. (3) Microscopic methods mainly include infrared spectroscopy and nuclear magnetic resonance, which analyze asphalt content through spectral characteristics and nuclear magnetic signals.

[0004] However, the main problems with the above methods for determining the asphalt content in mixtures are as follows:

[0005] (1) Extraction and separation method: This method requires the use of organic solvents (such as trichloroethylene), which are highly toxic and volatile, endangering the health of operators. In addition, the toxic solvents need to be recycled and disposed of, increasing environmental protection costs. At the same time, the processes of dissolving, centrifuging, and drying take several hours to a day, which cannot meet the needs of rapid feedback at the construction site. Furthermore, if the solvent does not completely dissolve the asphalt or if there is residual solvent on the surface of the aggregate, it can easily lead to errors in quality measurement. The problem of incomplete separation is even more prominent when processing high-viscosity modified asphalt or recycled mixtures with fine pores.

[0006] (2) Combustion method: The high-temperature treatment process of this method may change the physical or chemical properties of the mineral materials. For example, carbonate mineral materials (such as limestone) will decompose and release carbon dioxide at a high temperature of 500~600℃, resulting in the mineral material mass after combustion being lower than the true value, which in turn makes the calculated asphalt content too high. Lightweight porous aggregates (such as basalt) may break at high temperatures due to the escape of internal moisture or gas, further affecting the measurement accuracy.

[0007] (3) Microscopic methods: For example, infrared spectroscopy and nuclear magnetic resonance methods in microscopic methods require precise optical components and standard sample libraries for calibration. In addition, both methods have extremely high requirements for sample homogeneity. If the aggregate particle size distribution in the asphalt mixture is uneven or there are impurities (such as moisture and dust), it may cause signal interference or characteristic peak shift. Especially for aged asphalt or mixtures containing complex additives (such as modifiers and regenerators), the difficulty of spectral analysis increases significantly. It is necessary to combine complex algorithms or manual experience for correction, and the detection time is long (usually tens of minutes to several hours), which makes it difficult to meet the needs of rapid and large-scale detection at the construction site, further limiting its engineering applicability.

[0008] Therefore, there is an urgent need to develop a method and system that can quickly and accurately determine the asphalt content in asphalt mixtures. Summary of the Invention

[0009] The technical problem to be solved by this invention is to provide a rapid method and system for determining the asphalt content in asphalt mixtures. Its purpose is to address the shortcomings of existing technologies by achieving rapid, green, and high-precision determination of the asphalt content in asphalt mixtures without using toxic solvents or high-temperature combustion, and to overcome the drawbacks of traditional methods such as long processing time, complex operation, and damage to samples.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for rapid determination of asphalt content in asphalt mixtures, comprising the following steps:

[0012] S1. Pretreatment: After crushing the asphalt mixture, weigh it by mass M0.

[0013] S2, Low-temperature embrittlement: The asphalt mixture after S1 is crushed is immersed in the first solution at -25℃ to -30℃ and kept at a constant temperature for 15 to 20 minutes to embrittle it; the first solution is a calcium chloride (CaCl2)-ethylene glycol solution, and the mass ratio of its components is CaCl2: ethylene glycol: water = 3:2:5;

[0014] S3. Vibration separation: The material after S2 low-temperature embrittlement is continuously vibrated at a frequency of 15~20kHz for 10~30 minutes to peel off the asphalt mixture.

[0015] S4. Layered collection: Static separation of floating asphalt and settled aggregate;

[0016] S5. Weighing calculation: Collect the stone and dry it to constant weight M1. The mass percentage of asphalt in the asphalt mixture is w = ((M0-M1) / M0) × 100%.

[0017] Furthermore, the method also includes: S6, numerical correction: the mineral powder content is determined by a blank aggregate test of the same batch, and a correction coefficient K is obtained. The mass percentage of asphalt in the corrected asphalt mixture is w'=w±correction coefficient K, and the correction range is -0.05%~-0.1%.

[0018] Furthermore, M0 and M1 in S5 are accurate to 0.01g.

[0019] Furthermore, the density of the first solution in S2 is 1.32 ± 0.02 g / cm³. 3 Its freezing point is -45℃.

[0020] Secondly, the present invention provides a rapid asphalt content determination system in asphalt mixtures capable of implementing the above-mentioned method. The system includes a low-temperature constant-temperature chamber, a high-frequency vibration unit, a solution circulation module, and a static collection unit, wherein:

[0021] The low-temperature constant temperature chamber includes a chamber body, which is a double-layer vacuum insulated chamber consisting of an inner liner and an outer shell. The first cavity formed between the inner liner and the outer shell is filled with polyurethane foam. The second cavity formed by the inner liner is used to place the first low-temperature embrittlement solution and the crushed asphalt mixture immersed in the first solution. The low-temperature constant temperature chamber is equipped with a temperature control system to control the temperature of the chamber within a preset temperature range.

[0022] The high-frequency vibration unit is installed at the bottom of the low-temperature constant temperature chamber and is used to vibrate and peel off the asphalt mixture that has become brittle at low temperature inside the low-temperature constant temperature chamber.

[0023] The solution circulation module is used to input the first solution into the constant temperature chamber and discharge the upper layer of solution after vibration separation and static stratification.

[0024] The static collection unit includes a liftable filter screen and a liquid level detection sensor. The liquid level detection sensor has the following functions: (1) accurately identifying the layered interface after static settling, because the liquid level of the slurry after the mineral powder settles is difficult to distinguish with the naked eye; (2) avoiding the filter screen from moving and disturbing the newly separated asphalt flakes; (3) realizing full-process automation, reducing human error, and improving the accuracy of detection.

[0025] Furthermore, the low-temperature constant temperature chamber is equipped with a top cover, which is connected to the open end of the chamber body through a rubber sealing ring to achieve vacuum insulation.

[0026] Furthermore, a material collection tray is also provided at the bottom of the low-temperature constant temperature chamber.

[0027] Furthermore, a control panel is provided on the outer shell of the low-temperature constant temperature chamber.

[0028] Furthermore, the inner liner is made of stainless steel, and the outer shell is made of carbon steel.

[0029] Furthermore, the temperature control system includes a semiconductor refrigeration module, a temperature sensor, and a PID closed-loop controller. The semiconductor refrigeration module is electrically connected to the PID temperature control system and isolates internal and external heat exchange through a double-layer vacuum insulation cavity. It is used to control the temperature cooling range to a preset temperature with a temperature control accuracy of ±0.5℃.

[0030] The temperature sensor and semiconductor refrigeration module are housed inside the low-temperature constant temperature chamber.

[0031] Furthermore, the high-frequency vibration unit includes a vibration source and a frequency converter, which are electrically connected. The vibration source and the frequency converter are integrated into a vibration table, which is connected to the bottom of the low-temperature constant temperature chamber via support legs. The vibration table is used to control the vibration frequency to a preset frequency and the amplitude to be 1~5mm. The vibration source is a piezoelectric ceramic vibrator.

[0032] Furthermore, a pressure sensor is installed at the bottom of the low-temperature constant temperature chamber to monitor the frequency of the vibration source.

[0033] Preferably, the vibration source is a piezoelectric ceramic vibrator. This is because piezoelectric ceramics have irreplaceable advantages in high-frequency, low-amplitude operations, and can accurately match the peeling frequency of the mineral powder-asphalt interface, avoiding the pulverization of minerals caused by low-frequency, high-amplitude vibrations in traditional vibrators.

[0034] Furthermore, the solution circulation module includes a storage tank for loading the first solution and a circulation system. The low-temperature constant temperature chamber is provided with a bidirectional fluid interface. The storage tank is connected to the bidirectional fluid interface through a liquid delivery pipe. The circulation system includes a circulation pump. The storage tank is provided with a valve. The circulation pump and the valve are linked to control the inflow and outflow of liquid into the storage tank, thereby enabling the replenishment of the first solution into the inner liner of the low-temperature constant temperature chamber and the input of the recovered first solution into the storage tank.

[0035] Furthermore, the liftable filter assembly includes an electric push rod and a filter assembly. The electric push rod is used to drive the filter assembly to rise and fall vertically, controlling the rising and falling speed to be 0.5~2 mm / s. The liquid level detection sensor is signal-connected to the electric push rod and can synchronously match the real-time feedback signal of the liquid level detection sensor.

[0036] Furthermore, the filter mesh size of the filter assembly is 0.075 mm.

[0037] The present invention has the following beneficial effects:

[0038] This invention provides a rapid method and system for determining the asphalt content in asphalt mixtures. It employs a low-temperature catalytic and vibration separation process to peel off the asphalt mixture, and then separates it into asphalt and aggregate through static stratification. By calculating the weight difference between the aggregate and the asphalt mixture, the asphalt content can be determined. This invention achieves rapid, green, and high-precision determination of asphalt content in asphalt mixtures without using toxic solvents or high-temperature combustion, overcoming the drawbacks of traditional methods such as long processing time, complex operation, and sample damage. Compared to traditional extraction and combustion methods, which suffer from drawbacks such as complex operation, toxic solvents, and high-temperature ablation, this invention achieves equivalent peeling through mechanical and physical separation, avoiding health hazards to operators and damage to the sample structure, thus possessing high safety and repeatability.

[0039] This invention achieves rapid, non-destructive separation of asphalt and aggregates by constructing a low-temperature, closed reaction environment (-30℃ to -25℃ ± 0.5℃) and applying high-frequency vibration (15Hz-20Hz). Compared to traditional extraction and combustion methods, this invention eliminates the need for organic solvents and high-temperature treatment, reducing the total test time from 1.5-4 hours to approximately 35 minutes. Furthermore, the chemical composition of the sample remains unchanged, facilitating subsequent analysis and recovery. The method involves a five-step process: pretreatment, deep freezing, vibration-based peeling, stratified collection, and difference calculation. No chemical reactions are required throughout, preserving the intact structure of the aggregates. This method achieves rapid and effective peeling because the glass transition of asphalt at low temperatures significantly increases its brittleness (brittleness index increases from BI=220). Combined with high-frequency vibration above 15kHz, this overcomes interfacial adhesion, enabling rapid peeling. Simultaneously, automatic stratification via density-controlled solution eliminates manual separation, greatly improving efficiency and accuracy.

[0040] A further technical solution and principle of the present invention is to utilize the low-temperature embrittlement effect of asphalt. Specifically, when asphalt is below -20℃, its glass transition temperature (Tg) is triggered, the molecular chain segments freeze, and the brittleness index (BI) increases from 2~3 at room temperature to 15~20 (ASTM D746 test data). The impact strength decreases by 90%, and it can be completely broken by high-frequency vibration (15~20kHz). Experimental verification shows that in an environment of -25℃, the asphalt-aggregate interface bonding force decays to <0.1MPa (measured by an adhesion tester), which can meet the mechanical peeling threshold.

[0041] To realize the rapid determination method for asphalt content in asphalt mixtures provided by this invention, the accompanying rapid determination system for asphalt content in asphalt mixtures is also simple in structure and easy to implement.

[0042] In summary, the rapid determination method (system) for asphalt content in asphalt mixtures proposed in this invention achieves rapid and accurate determination of asphalt content through "low-temperature embrittlement-high-frequency vibration-density stratification," without chemical reactions and under environmentally friendly and safe conditions. Multiple comparative experiments demonstrate that this invention significantly outperforms existing mainstream testing methods in terms of stripping efficiency, time cost, and ease of operation, exhibiting promising engineering application prospects and industrialization value. This invention can be widely applied to quality monitoring at road construction sites, quality inspection at the production line end, and asphalt material performance analysis experiments in universities / research institutions, providing a safe, environmentally friendly, and scalable solution for rapid quality assessment of asphalt mixtures. Attached Figure Description

[0043] Figure 1 This is a flowchart illustrating the rapid determination method for asphalt content in asphalt mixtures provided by the present invention.

[0044] Figure 2 This is a cross-sectional view of the overall structure of the rapid asphalt content determination system in asphalt mixtures provided by the present invention.

[0045] Figure 3 A three-dimensional structural diagram of the low-temperature constant temperature chamber of the rapid asphalt content determination system in asphalt mixtures provided by the present invention.

[0046] Figure 4 This is a schematic diagram of the overall appearance of the rapid asphalt content determination system in asphalt mixtures provided by the present invention.

[0047] Figure 5 This is a flowchart illustrating the numerical correction calculation process in an embodiment of the present invention.

[0048] Explanation of reference numerals in the attached diagram: 1 Outer shell, 2 Inner liner, 3 Top cover, 4 Rubber sealing ring, 5 Vibration table, 6 Electric push rod, 7 Liquid level sensor, 8 Support foot, 9 Bidirectional fluid interface, 10 Infusion pipe, 11 Valve, 12 Storage tank, 13 Semiconductor refrigeration module, 14 Collection tray, 15 Humidity sensor, 16 Pressure sensor, 17 Temperature sensor, 18 Filter screen assembly, 19 Negative pressure extraction port, 20 Control panel. Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be further explained below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0050] like Figure 1 As shown, the present invention provides a method for rapidly determining the asphalt content in asphalt mixtures, comprising the following steps:

[0051] S1. Pretreatment: Crush the asphalt mixture to a particle size ≤10mm and weigh it to a mass M0; M0 is accurate to 0.01g.

[0052] S2. Low-temperature embrittlement: Immerse the crushed asphalt mixture from S1 into a first solution at -25℃ to -30℃ and maintain the temperature for 15 to 20 minutes to embrittle it. The first solution is a calcium chloride-ethylene glycol solution with a mass ratio of CaCl2:ethylene glycol:water = 3:2:5; the density of the first solution is 1.32 ± 0.02 g / cm³, and the freezing point is -45℃.

[0053] S3, Vibration Separation: The material after S2 low-temperature embrittlement is continuously vibrated at a frequency of 15~20kHz for 10~30 minutes to peel off the asphalt mixture.

[0054] S4. Layered collection: The floating asphalt layer and the bottom stone are separated by static settling, which can generally be achieved in 5 to 10 minutes.

[0055] S5. Weighing calculation: Collect the stone and dry it to a constant weight M1, M1 accurate to 0.01g; the mass percentage of asphalt in the asphalt mixture w=((M0-M1) / M0)×100%.

[0056] S6. Numerical correction: The mineral powder content is determined by testing blank aggregates of the same batch, and the correction coefficient K is obtained. The mass percentage of asphalt in the corrected asphalt mixture is w' = w ± correction coefficient K, and the correction range is -0.05% to -0.1%.

[0057] In the same batch of blank stone material test, the following points need to be noted: (1) Material aspect: The blank stone material must be of the same origin and quality as the aggregate of the tested mixture. If the original sample is limestone crushed stone, the blank sample must also be material from the same quarry and production line. The particle size distribution must be completely consistent, which requires screening and remixing according to the specifications. (2) Process aspect: The mechanical damage of the real working conditions must be simulated during processing (e.g., using a Los Angeles abrasion mill at 500 revolutions), but skip the asphalt wrapping step. The vibration parameters must be exactly the same as the test sample, including solution temperature, amplitude frequency, action time, etc. (3) Data processing aspect: It is more reasonable to use the initial mass (rather than the mass after testing) in the denominator of the K value calculation formula, so as to avoid the error of mineral powder adhering to the filter screen. The number of parallel tests is 5, because the mineral powder loss has obvious dispersion, and more accurate data can be obtained. Since the traditional extraction method does not correct for mineral powder loss, the results are too high; the correction logic of this method is similar to the blank deduction method of the base material in the determination of air content of cement concrete, and the data after correction is more accurate.

[0058] Example 1

[0059] like Figures 2-4 As shown, to achieve the method for rapidly determining the asphalt content in asphalt mixtures according to the present invention, this embodiment provides a rapid asphalt content determination system for asphalt mixtures. The system includes a low-temperature constant-temperature chamber, a high-frequency vibration unit, a solution circulation module, and a static collection unit. In a specific embodiment, firstly, an appropriate amount of the asphalt pavement material sample to be tested is placed in a low-temperature constant-temperature chamber containing a low-temperature solution and kept for 15-20 minutes. Then, the high-frequency vibration unit causes the asphalt on the surface of the aggregate to become brittle and fall off. Subsequently, the stratification effect caused by the density difference between the asphalt, aggregate, and solution is used to separate the detached asphalt and aggregate. The static collection unit collects the sample. Finally, after the surface solution has dried, the asphalt and aggregate are weighed separately to calculate the asphalt content.

[0060] In a preferred embodiment, the low-temperature constant-temperature chamber includes a chamber body, which is a double-layered vacuum insulated cavity consisting of an inner liner layer 2 and an outer shell 1. The first cavity formed between the inner liner layer 2 and the outer shell 1 is filled with polyurethane foam. The second cavity formed by the inner liner layer 2 is used to hold the first low-temperature embrittlement solution and the crushed asphalt mixture immersed in the first solution. The low-temperature constant-temperature chamber is equipped with a temperature control system to control the chamber's temperature cooling range to a preset temperature. In a preferred embodiment, the temperature control system includes a semiconductor cooling module 13, a temperature sensor 17, and a PID closed-loop controller (temperature controller). The temperature sensor 17 and the semiconductor cooling module 13 are located within the chamber body of the low-temperature constant-temperature chamber. The temperature cooling range is controlled to be -30℃ to 0℃, with a temperature control accuracy of ±0.5℃. To achieve better peeling results, during specific measurements, the temperature of the first solution within the low-temperature constant-temperature chamber is controlled at -30℃ to -25℃, which is the optimal low-temperature embrittlement temperature.

[0061] The high-frequency vibration unit is installed at the bottom of the low-temperature constant-temperature chamber and includes a vibration source and a frequency converter. The vibration source and the frequency converter are electrically connected. The vibration source (not shown in the figure) and the frequency converter (not shown in the figure) are integrated into a vibration table 5. The vibration table 5 is connected to the bottom of the low-temperature constant-temperature chamber via support legs 8 and is used for vibration stripping the asphalt mixture that has become brittle at low temperatures inside the low-temperature constant-temperature chamber. A pressure sensor 16 is also provided at the bottom of the low-temperature constant-temperature chamber to monitor the frequency of the vibration source and control the vibration frequency to be 10~20kHz and the amplitude to be 1~5mm. To achieve better stripping effect, the vibration separation frequency is controlled at 15~20kHz during specific measurements, which is considered the optimal vibration separation frequency.

[0062] The solution circulation module is used to input a first solution into a cryogenic chamber and, after vibration separation and settling, discharge the upper layer of solution. As an exemplary preferred embodiment, the solution circulation module includes a storage tank 12 for loading the first solution and a circulation system. The cryogenic chamber is equipped with a bidirectional fluid interface 9. The storage tank 12 is connected to the bidirectional fluid interface 9 via a delivery pipe 10. The circulation system includes a circulation pump (not shown in the figure), and the storage tank 12 is equipped with a valve 11. The circulation pump and valve 11 are linked to control the inflow and outflow of liquid into the storage tank 12, thereby replenishing the cryogenic chamber with the first solution and inputting the recovered first solution into the storage tank 12. In specific implementations, the discharged upper layer solution typically requires purification treatment to achieve recycling.

[0063] The static collection unit includes a liftable filter assembly and a liquid level sensor 7. The liquid level sensor 7 has the following functions: (1) accurately identifying the layered interface after static settling, because the slurry level after mineral powder sedimentation is difficult to distinguish with the naked eye; (2) avoiding the filter moving and disturbing the newly separated asphalt flakes; (3) realizing full-process automation, reducing human error, and improving detection accuracy. In this embodiment, the liquid level sensor 7 is an ultrasonic level gauge. As a preferred embodiment, the liftable filter assembly includes an electric push rod 6 and a filter assembly 18. The electric push rod 6 is used to drive the filter assembly 18 to rise and fall vertically, controlling the rising and falling speed to be 0.5~2 mm / s; the liquid level sensor 7 is signal-connected to the electric push rod 6 and can synchronously match the real-time feedback signal of the liquid level sensor 7. The filter mesh diameter of the filter assembly 18 is 0.075 mm.

[0064] In a preferred embodiment, the low-temperature constant-temperature chamber in this embodiment is equipped with a top cover 3, which is connected to the open end of the chamber body via a rubber sealing ring 4 to achieve vacuum insulation. The bottom of the low-temperature constant-temperature chamber is also equipped with a collection tray 14 for collecting the separated sediment.

[0065] In a preferred embodiment, the inner liner 2 is made of stainless steel, and the outer shell 1 is made of carbon steel. Specifically, in this embodiment, the enclosure uses a double-layer vacuum insulation cavity: the inner liner 2 is made of SUS304 stainless steel (2mm thick), the outer shell 1 is made of Q235 carbon steel (3mm thick), and the cavity is filled with 50mm of polyurethane foam (thermal conductivity ≤0.022 W / m·K). The temperature control system uses a semiconductor refrigeration module (model TEC1-12706×6 sets), equipped with a PT100 temperature sensor (±0.1℃) and a PID closed-loop controller (STM32F407); the STM32F407 microcontroller is equipped with a PID algorithm and uses the PT100 temperature sensor (accuracy ±0.1℃) for real-time closed-loop adjustment.

[0066] The cooling verification was performed using an infrared thermal imager (FLIR E6) to monitor the surface temperature uniformity of the sample within ±0.5℃, and the sample was cooled to -30℃ within 15 minutes.

[0067] In this embodiment, the vibration source of the high-frequency vibration unit is a piezoelectric ceramic stack (PSt 150 / 5×5×20, PI, Germany), with an amplitude of 1-5 mm and a frequency of 10-20 kHz. The verification method is to measure the maximum vibration acceleration of the sample groove (5.2 g at 5 mm amplitude) by an ICP accelerometer, with frequency fluctuation ≤ ±0.3 kHz. The interface peeling effect was tested on the SBS modified bitumen-basalt interface (initial bond strength 0.8 MPa). Vibration at -25℃ for 10 minutes at 15 kHz resulted in a peeling strength of 0.08 MPa (measured by ASTM D4541).

[0068] The drive voltage is adjustable from 0-200V, and the transmission mechanism uses a stainless steel elastic connecting rod (8mm in diameter) and a shock-absorbing rubber pad (50 Shore A hardness) to ensure efficient energy transfer to the sample. The upper limit of vibration acceleration is set to 5g (monitored by an ICP accelerometer), and the machine will automatically stop if the limit is exceeded.

[0069] In this embodiment, the first solution is selected as a calcium chloride-ethylene glycol solution (CaCl2:ethylene glycol:H2O=3:2:5, density 1.32±0.02g / cm³, freezing point -45℃), with a circulation flow rate of 3L / min, driven by a magnetic pump (ITT MD-10); the viscosity is controlled at 42mPa·s at -30℃ (measured by a rotational viscometer, ISO 3219 standard) to ensure the suspension and flow of asphalt debris.

[0070] In this embodiment, the static collection unit is implemented as follows: After the vibration static settling period, the upper layer of asphalt debris and aggregate naturally separate into layers in the solution due to density differences. The filter assembly 18 is then activated, followed by the rising mode. An electric push rod 6 drives the filter assembly 18 to rise vertically, filtering and removing the upper layer of asphalt debris. Automatic liquid extraction is then activated, and the solution enters the storage tank 12 through the bidirectional fluid interface 9. After drainage is complete, air is extracted through the negative pressure extraction port 19, creating a negative pressure state inside the low-temperature constant temperature chamber. The drying mode is then activated, and the aggregate drying progress is monitored on the control panel 20 of the outer casing 1 via the humidity sensor 15, enabling automatic drying. Finally, a weighing measurement is performed.

[0071] Specifically, after vibration, the solution is allowed to stand for 10 minutes, during which time it will naturally separate into layers. The upper layer consists of suspended asphalt debris (particle size 0.1-2mm), and the lower layer consists of fully settled aggregate (settling velocity > 5cm / min, calculated according to Stokes' law). Then, a siphon is used to drain the solution, and a vacuum pump is started to draw the upper layer solution into a recovery tank at a flow rate of 3L / min, while simultaneously monitoring the liquid level. When the liquid level drops to 10mm from the bottom of the container (as indicated by an ultrasonic level gauge), drainage is stopped to prevent aggregate loss. A pneumatic valve is opened, and the settled aggregate falls into a collection tray after being filtered through a screen, which blocks >99% of the asphalt debris. Simultaneously, auxiliary vibration is applied along the outer wall of the discharge port at a 50Hz micro-vibration (amplitude 0.2mm) to prevent aggregate jamming.

[0072] Example 2

[0073] This embodiment provides a method for rapidly determining the asphalt content in asphalt mixtures, implemented using the apparatus provided in Embodiment 1 above, and specifically includes the following steps:

[0074] S1. Pretreatment: Crush the AC-13 asphalt mixture sample to a particle size ≤10mm (conforming to the gradation curve of JTJ 058-2000) and weigh it to a mass M0=500.00g (accuracy 0.01g).

[0075] Crushing verification: The D50 of the crushed sample was measured to be 4.2 mm using a laser particle size analyzer (Malvern Mastersizer 3000).

[0076] S2, Low-temperature embrittlement: The asphalt mixture after S1 was immersed in the first solution at -25℃ and kept at a constant temperature for 16 minutes (actual solution temperature -25.3℃±0.4℃), triggering the glass transition of the asphalt (DSC test Tg=-23.5℃). The performance of the constant temperature system is shown in Table 1.

[0077]

[0078] To verify the effect of different initial solutions on the low-temperature catalytic effect, the following density difference chromatography separation experiment was conducted:

[0079] A density gradient solution (1.1~1.5 g / cm³) was selected. 3 ), ensuring that the asphalt debris (ρ≈1.03g / cm) 3 The stone (ρ>2.6g / cm³) floats to the surface. 3 (It will sink.) See Table 2 for solution selection criteria.

[0080]

[0081] Based on the standards in Table 2, four solutions were selected: CaCl2-ethylene glycol aqueous solution (the mass ratio of CaCl2:ethylene glycol:H2O is 3:2:5), PFPE, saturated NaCl aqueous solution, and glycerol-water (50%). The physical properties of these four solutions were compared and analyzed, and the results are shown in Table 3 below.

[0082]

[0083] As shown in Table 3, both the calcium chloride-ethylene glycol aqueous solution and the perfluoropolyether oil (PFPE) exhibit high stripping rates. However, considering the higher cost of PFPE, the calcium chloride-ethylene glycol aqueous solution is selected as the first solution for low-temperature catalysis in S2 in this embodiment and subsequent specific embodiments. The selected calcium chloride-ethylene glycol solution has a CaCl2:ethylene glycol:water mass ratio of 3:2:5 and a density of 1.32 ± 0.02 g / cm³. 3 Its freezing point is -45℃.

[0084] S3. Vibration stripping: High-frequency vibration (frequency 15kHz, amplitude 3mm) was started and continued for 10 minutes. The particle size of asphalt debris in the mixture after stripping was measured to be 0.1~1.2mm by laser diffraction analysis. The analysis results are shown in Table 4.

[0085]

[0086] S4. Layered collection: After standing and layering, collect the asphalt debris from the upper layer (filter retention rate ≥99.8%), and dry the ore to constant weight M1=456.23g.

[0087] S5. Weighing calculation: Asphalt content w = ((500.00-456.23) / 500.00) × 100% = 8.75%.

[0088] S6. Numerical Correction: Mineral Loss Correction: Based on a blank test of the same batch of basalt, the mineral powder loss Δ = -0.08% (three-fold average), and a correction coefficient K = -0.08% is set. The calculation process is as follows: Figure 5 As shown.

[0089] The corrected asphalt mixture contains the following mass percentage of asphalt:

[0090] w'=w±correction coefficient K=8.75%±0.12%, with an error of <1% compared to the extraction method (8.6%).

[0091] The closed-loop quality verification system establishes a calibration curve through blank tests (pure stone pretreatment), and introduces a compensation coefficient K (range ±0.2%) into the calculation formula to eliminate the influence of solution residue on stone weighing.

[0092] To verify the criticality of low temperature in the asphalt embrittlement stripping effect, this invention also included a comparative test of stripping efficiency at different temperatures. The catalytic temperature in step S2 of Example 2 was adjusted to -30℃, -20℃, -10℃, and room temperature 25℃, while other parameters remained consistent (vibration frequency 15kHz, amplitude 3mm, vibration time 10min, and samples were AC-13 mixtures from the same batch). The stripping rate was defined as the proportion of recyclable asphalt debris to the theoretical content after the test, and the results are shown in Table 5 below.

[0093]

[0094] The data in Table 5 indicate that below the glass transition temperature of the asphalt (approximately -23°C) is the critical condition for effective stripping. The preferred embrittlement temperature in this scheme is -25°C to 30°C.

[0095] To verify the effect of vibration at different frequencies on peeling efficiency, this invention also included a comparative test of peeling efficiency under different vibration frequencies. Under a constant temperature embrittlement environment of -25℃, the vibration frequency in S3 of Example 2 was adjusted to 5kHz, 10kHz, and 20kHz for the test. All other parameters remained unchanged. The peeling rate results are shown in Table 6 below:

[0096]

[0097] The results show that the asphalt stripping effect is significantly enhanced when the frequency is ≥15kHz, and there is no significant gain when the frequency is further increased to 20kHz, indicating that separation can be completed when the vibration energy reaches the critical point. Therefore, the preferred frequency for vibration separation after embrittlement stripping in this scheme is 15~20kHz.

[0098] In summary, the solution provided by this invention achieves rapid and non-destructive separation of asphalt and aggregates by constructing a low-temperature, closed reaction environment (-30℃ to -25℃) and applying high-frequency vibration (15~20kHz). Compared to traditional extraction and combustion methods, this invention eliminates the need for organic solvents and high-temperature treatment, reducing the total test time from 1.5~4 hours to approximately 35 minutes, while preserving the intact sample structure for subsequent analysis and recovery. The method of this invention completes the detection through "pretreatment - deep freezing - vibration peeling - stratified collection - difference calculation," requiring no chemical reaction throughout and preserving the complete structure of the aggregates. The reason this method can achieve rapid and effective peeling is that at low temperatures, the glass transition effect of asphalt significantly increases its brittleness (brittleness index increases from BI=220), and combined with high-frequency vibration above 15kHz, it can overcome interfacial adhesion to achieve rapid peeling. Simultaneously, automatic stratification is achieved through density-controlled solution, eliminating the need for manual separation and greatly improving the efficiency and accuracy of the measurement.

[0099] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A rapid method for determining the asphalt content in asphalt mixtures, characterized in that, Includes the following steps: S1. Pretreatment: After crushing the asphalt mixture, weigh it by mass M0. S2. Low-temperature embrittlement: The asphalt mixture after S1 is crushed is immersed in the first solution at -25℃ to -30℃ and kept at a constant temperature for 15 to 20 minutes to make it embrittled; the first solution is a calcium chloride-ethylene glycol solution, and the mass ratio of its components is CaCl2: ethylene glycol: water = 3: 2:

5. S3. Vibration separation: The material after S2 low-temperature embrittlement is continuously vibrated at a frequency of 15~20kHz for 10~30 minutes to peel off the asphalt mixture. S4. Layered collection: Static separation of floating asphalt and settled aggregate; S5. Weighing calculation: Collect the stone and dry it to constant weight M1. The mass percentage of asphalt in the asphalt mixture is w = ((M0-M1) / M0) × 100%.

2. The method for rapid determination of asphalt content in asphalt mixtures according to claim 1, characterized in that, The method further includes: S6. Numerical correction: The mineral powder content is determined by testing blank aggregates of the same batch, and the correction coefficient K is obtained. The mass percentage of asphalt in the corrected asphalt mixture is w' = w ± correction coefficient K, and the correction range is -0.05% to -0.1%.

3. The rapid determination method for asphalt content in asphalt mixtures according to claim 1, characterized in that, In S5, M0 and M1 are accurate to 0.01g.

4. The rapid determination method for asphalt content in asphalt mixtures according to claim 1, characterized in that, The density of the first solution in S2 is 1.32 ± 0.02 g / cm³. 3 Its freezing point is -45℃.

5. A rapid asphalt content determination system for asphalt mixtures capable of implementing the method described in any one of claims 1 to 4, characterized in that, The system includes a low-temperature constant-temperature chamber, a high-frequency vibration unit, a solution circulation module, and a static collection unit, wherein: The low-temperature constant temperature chamber includes a chamber body, which is a double-layer vacuum insulated chamber consisting of an inner liner and an outer shell. The first cavity formed between the inner liner and the outer shell is filled with polyurethane foam. The second cavity formed by the inner liner is used to place the first low-temperature embrittlement solution and the crushed asphalt mixture immersed in the first solution. The low-temperature constant temperature chamber is equipped with a temperature control system to control the temperature of the chamber within a preset temperature range. The high-frequency vibration unit is installed at the bottom of the low-temperature constant temperature chamber and is used to vibrate and peel off the asphalt mixture that has become brittle at low temperature inside the low-temperature constant temperature chamber. The solution circulation module is used to input the first solution into the constant temperature chamber and discharge the upper layer of solution after vibration separation and static stratification. The static collection unit includes a liftable filter assembly and a liquid level detection sensor.

6. The rapid determination system for asphalt content in asphalt mixtures according to claim 5, characterized in that, The low-temperature constant temperature chamber is equipped with a top cover, which is connected to the open end of the chamber body through a rubber sealing ring to achieve vacuum insulation. The bottom of the low-temperature constant temperature chamber is also equipped with a material collection tray; The low-temperature constant temperature chamber is equipped with a control panel on its outer shell; The inner liner is made of stainless steel, and the outer shell is made of carbon steel.

7. The rapid determination system for asphalt content in asphalt mixtures according to claim 5, characterized in that, The temperature control system includes a semiconductor refrigeration module, a temperature sensor, and a PID closed-loop controller. The semiconductor refrigeration module is electrically connected to the PID temperature control system and isolates internal and external heat exchange through a double-layer vacuum insulation cavity. It is used to control the temperature cooling range to a preset temperature with a temperature control accuracy of ±0.5℃. The temperature sensor and semiconductor refrigeration module are housed inside the low-temperature constant temperature chamber.

8. The rapid determination system for asphalt content in asphalt mixtures according to claim 5, characterized in that, The high-frequency vibration unit includes a vibration source and a frequency converter, which are electrically connected. The vibration source and the frequency converter are integrated into a vibration table, which is connected to the bottom of the low-temperature constant temperature chamber via support legs. The vibration table is used to control the vibration frequency to a preset frequency and the amplitude to be 1~5mm. The vibration source is a piezoelectric ceramic vibrator. A pressure sensor is also provided at the bottom of the low-temperature constant temperature chamber to monitor the frequency of the vibration source.

9. The rapid determination system for asphalt content in asphalt mixtures according to claim 5, characterized in that, The solution circulation module includes a storage tank for loading the first solution and a circulation system. The low-temperature constant temperature chamber is provided with a bidirectional fluid interface. The storage tank is connected to the bidirectional fluid interface through a liquid delivery pipe. The circulation system includes a circulation pump. The storage tank is provided with a valve. The circulation pump and the valve are linked to control the inflow and outflow of liquid into the storage tank, so as to replenish the first solution into the inner liner of the low-temperature constant temperature chamber and input the recovered first solution into the storage tank.

10. The rapid determination system for asphalt content in asphalt mixtures according to claim 5, characterized in that, The liftable filter assembly includes an electric push rod and a filter assembly. The electric push rod is used to drive the filter assembly to lift vertically, and the lifting speed is controlled to be 0.5~2 mm / s. The liquid level detection sensor is connected to the electric push rod and can synchronously match the real-time feedback signal of the liquid level detection sensor. The filter mesh diameter of the filter assembly is 0.075mm.

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