Modified asphalt performance detection method based on volatile component release characteristics

Abstract

The invention relates to the technical field of asphalt performance detection, and discloses a volatile component release characteristic-based modified asphalt performance detection method which comprises the following steps: preparing a thin-layer sample and putting the thin-layer sample into a closed detection chamber; linear temperature rise and flow rate switching are carried out to construct a dynamic mass transfer environment; detecting gas concentration to generate a response curve containing fluctuation characteristics; analyzing the curve to construct flow velocity sensitive and insensitive characteristic components; and determining the swelling or dispersing performance of the rubber powder based on the characteristic component. The method comprises the following steps: by superposing a periodically changing carrier gas flow velocity in a continuous heating process, separating a mixed gas concentration signal value into a flow velocity sensitive component and a flow velocity insensitive component by utilizing a dynamic difference that a surface free component is controlled by external convective mass transfer and an internal swelling component is controlled by internal diffusion; no physical separation or chemical extraction is needed, and free oil components which do not participate in the reaction and swelling oil components which are absorbed by rubber powder in the asphalt can be quantitatively distinguished.

Description

Technical Field

[0001] This invention relates to the field of asphalt performance testing technology, specifically to a method for testing the performance of modified asphalt based on the release characteristics of volatile components. Background Technology

[0002] Modified asphalt from waste tire rubber powder is a key material for achieving resource recycling in road engineering. Its performance depends on the interaction between the rubber powder particles and the base asphalt. Under ideal conditions, the rubber powder particles absorb lightweight components such as aromatics and saturates from the base asphalt, causing them to swell and expand in volume to form a viscoelastic interfacial gel layer. This, in turn, constructs a stable three-dimensional network structure, giving the pavement excellent crack resistance and fatigue resistance.

[0003] Current quality evaluation systems primarily rely on macroscopic physical indicators and microscopic auxiliary observations. In engineering applications, indicators such as penetration, softening point, ductility, and viscosity are commonly used to accept products. For microscopic analysis, fluorescence microscopy is used to observe the dispersion state of rubber powder in the asphalt phase and the characteristics of particle edges. For component composition analysis, existing techniques often employ Soxhlet extraction and column chromatography using organic solvents for component separation, or use thermogravimetric analysis to determine the thermal weight loss behavior of materials during heating.

[0004] However, existing modified asphalt performance testing technologies rely on macroscopic physical indicators that are averaged descriptions of the overall rheological properties of the material. These technologies are slow to respond to changes in phase structure and struggle to effectively identify the state of insufficiently swollen rubber powder. Fluorescence microscopy observations primarily depend on two-dimensional images, and the determination of the degree of swelling relies on human experience, making it difficult to quantify the actual adsorption amount of light components within the rubber powder. Chemical separation methods, due to the introduction of organic solvents, easily disrupt the original adsorption equilibrium between the rubber powder and asphalt, reverse-extracting swollen components that have already entered the rubber powder, thus destroying the original state of the sample. Furthermore, conventional thermogravimetric analysis can only record the total mass loss; during the heating process, the volatilization of free light components on the surface and the diffusion and release of components bound by the rubber powder highly overlap in time. Therefore, this invention provides a modified asphalt performance testing method based on the release characteristics of volatile components to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for testing the performance of modified asphalt based on the release characteristics of volatile components. This method solves the problem that existing testing techniques are unable to decouple and quantitatively distinguish between free and swollen components in modified asphalt in situ without disrupting the original adsorption equilibrium of the sample, thus making it difficult to accurately evaluate the degree of swelling and dispersion uniformity of the asphalt powder.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for testing the performance of modified asphalt based on the release characteristics of volatile components, comprising the following steps: S1. The modified asphalt sample to be tested is coated on the surface of an inert carrier to form a thin layer sample, and the inert carrier carrying the thin layer sample is placed into a sealed testing chamber with temperature control and gas flow control functions. S2. Control the temperature of the sealed detection chamber to rise linearly from the starting temperature to the ending temperature at a preset heating rate, and control the carrier gas flow rate entering the sealed detection chamber to alternate between the first flow rate value and the second flow rate value according to a preset modulation period to construct a dynamic mass transfer environment. S3. Continuously detect the gas concentration at the outlet of the sealed detection chamber using a gas detection device, and generate a gas concentration response curve that exhibits fluctuating characteristics synchronously with the switching of carrier gas flow rate. S4. Analyze the gas concentration response curve, extract the fluctuation amplitude of the flow rate switching in each modulation cycle to construct the flow rate sensitive component, and extract the concentration reference value in each modulation cycle to construct the flow rate insensitive component. The flow rate sensitive component represents the free volatile components on the sample surface, and the flow rate insensitive component represents the diffused release components inside the sample. S5. Calculate the swelling evaluation index using the numerical relationship between the flow rate insensitive component and the flow rate sensitive component in a specific temperature range to determine the degree of swelling of the adhesive powder, or use the degree of difference between the flow rate sensitive components generated at different sampling points to determine the uniformity of adhesive powder dispersion.

[0007] Preferably, in step S2, constructing the dynamic mass transfer environment includes: For thermal field control, the initial temperature is set to 60 degrees Celsius to 80 degrees Celsius, the final temperature is set to 180 degrees Celsius to 200 degrees Celsius, and the heating rate is set to 5 degrees Celsius to 20 degrees Celsius per minute; For flow field control, the modulation period of the carrier gas flow rate is set to 10 seconds to 60 seconds, the first flow rate value is set to 100 ml / min to 500 ml / min, and the second flow rate value is set to 0 ml / min to 50 ml / min.

[0008] Preferably, in step S4, the step of constructing the flow rate sensitive component further includes: Within each modulation cycle, the signal value corresponding to the end of the high flow rate phase of the first flow rate value and the signal value corresponding to the end of the low flow rate phase of the second flow rate value are identified. Calculate the absolute value of the difference between the signal value at the end of the low flow rate phase and the signal value at the end of the high flow rate phase after high-low flow rate ratio correction, and use the absolute value as the flow rate sensitive component value corresponding to the current modulation period.

[0009] Preferably, in step S4, the step of constructing the flow velocity insensitivity component further includes: Based on the signal values ​​at the end of the low flow rate phase and the end of the high flow rate phase, the arithmetic mean of the signal value at the end of the low flow rate phase and the signal value at the end of the high flow rate phase after high-low flow rate ratio correction is calculated, and the arithmetic mean is used as the flow rate insensitivity component value corresponding to the current modulation period.

[0010] Preferably, in step S5, the step of determining the degree of swelling of the adhesive powder further includes: Select a preset simulated construction temperature range, calculate the percentage of the integral area of ​​the insensitive flow velocity component within the construction temperature range to the sum of the integral areas of the insensitive flow velocity component and the integral areas of the sensitive flow velocity component, and obtain the swelling efficiency index. The swelling efficiency index is compared with a preset swelling threshold. When the swelling efficiency index is greater than the preset swelling threshold, the rubber powder swelling development of the modified asphalt sample is deemed qualified.

[0011] Preferably, in step S5, the step of determining the uniformity of the adhesive powder dispersion further includes: Multiple samples were taken from the same batch of modified asphalt products and steps S1 to S4 were performed respectively to obtain the flow rate sensitive component curves of each of the multiple parallel samples. Extract the characteristic peaks from the flow rate sensitive component curve and calculate the coefficient of variation of the characteristic peaks; The coefficient of variation is compared with a preset uniformity threshold. When the coefficient of variation is less than the uniformity threshold, the rubber powder of the modified asphalt sample is determined to be uniformly dispersed.

[0012] Preferably, S5 further includes an evaluation of the aging state of the modified asphalt, further comprising: On the continuous curve generated corresponding to the insensitive component of the flow velocity, the slope variation characteristics in the high temperature range above 180 degrees Celsius were observed. When the generated continuous curve shows a sudden change point with a sharp increase in slope or a second rising peak in the high temperature range, and the corresponding flow rate sensitive component remains at a low level, it is determined that the modified asphalt sample has a risk of aging failure.

[0013] Preferably, in step S1, the coating thickness of the thin-layer sample is between 0.5 mm and 1 mm to eliminate the thermal conductivity gradient inside the sample, and the sealed detection chamber is made of an inert material that does not adsorb organic volatiles, and the internal free space volume is between 10 ml and 50 ml.

[0014] Preferably, in step S3, the gas detection device is a photoionization detector or a metal oxide semiconductor sensor array, and the data sampling frequency of the gas concentration response curve is set to 1 Hz to 10 Hz to fully record the transient waveform generated by the flow rate switching.

[0015] Preferably, S1 further includes: Inert gas at a constant flow rate is introduced into the sealed detection chamber and maintained for 1 to 3 minutes; The inert gas is used to replace the ambient air in the sealed detection chamber to provide an oxygen-free baseline.

[0016] This invention provides a method for testing the performance of modified asphalt based on the release characteristics of volatile components. It has the following beneficial effects: 1. This invention, by superimposing periodically varying carrier gas flow rates during continuous heating, utilizes the kinetic difference between surface free components controlled by external convection and internal swollen components controlled by internal diffusion to separate the mixed gas concentration signal into flow rate-sensitive and flow rate-insensitive components. Without the need for physical separation or chemical extraction, it can quantitatively distinguish between unreacted free oil and swollen oil absorbed by rubber powder in asphalt, thereby accurately evaluating the degree of swelling development of rubber powder.

[0017] 2. This invention employs thin-layer sampling combined with programmed temperature rise technology, which can simulate the component release behavior of modified asphalt at actual construction and storage temperatures. Compared with fluorescence microscopy observation or solvent extraction methods, it avoids the errors introduced by complex chemical pretreatment steps, and a single test can cover a wide temperature range. The response curve obtained through flow rate modulation technology can truly reflect the interaction state between rubber powder and base asphalt under thermal action, providing a test basis that conforms to actual working conditions for the formulation screening and process optimization of modified asphalt.

[0018] 3. This invention constructs a multi-dimensional quality evaluation system that includes swelling, uniformity, and thermal stability. It not only uses the flow rate insensitivity component to characterize the degree of swelling, but also uses the coefficient of variation of the flow rate sensitive component from multi-point sampling to determine the dispersion uniformity of the rubber powder in the matrix. Furthermore, it identifies the risk of thermal decomposition and aging of the rubber powder by monitoring the abnormal abrupt changes in the flow rate insensitivity component in the high-temperature zone. This analytical method based on the kinetics of volatile component release compensates for the insufficiency of conventional physical indicators such as softening point and penetration in responding to changes in the microstructure of materials, and can more sensitively detect potential quality defects in modified asphalt. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method steps of the present invention; Figure 2 This is a diagram of the performance testing system architecture of the present invention; Figure 3This is a flowchart of the performance evaluation process of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See attached document Figure 1 , Figure 1 This is a flowchart of a method according to an embodiment of the present invention. The present invention provides a method for testing the performance of modified asphalt based on the release characteristics of volatile components, comprising the following steps: S1. Perform the sample preparation and loading steps. Obtain the high-content rubber-modified asphalt sample to be tested. Coat a quantitative amount of the sample onto the surface of an inert carrier to form a thin layer sample of uniform thickness. Place the inert carrier carrying the thin layer sample into a sealed testing chamber with temperature control and gas flow control functions.

[0022] S2. Perform the thermal and flow field coupling excitation step. Following a preset heating rate, control the temperature of the sealed detection chamber to linearly increase from the initial temperature to the final temperature. During the heating process, control the carrier gas flow rate entering the sealed detection chamber to alternate between a first flow rate value and a second flow rate value according to a preset modulation period. The first flow rate value is greater than the second flow rate value, thereby creating a periodically changing convective mass transfer environment within the sealed detection chamber.

[0023] S3. Execute the response signal acquisition step. Simultaneously with the thermal field and flow field coupling excitation step, the gas concentration at the outlet of the sealed detection chamber is continuously detected using a gas detection device. The value of the gas concentration changing over time is recorded, generating a gas concentration response curve. The gas concentration response curve exhibits a characteristic of fluctuating with the switching of the carrier gas flow rate.

[0024] S4. Perform signal decoupling processing. Numerical analysis is performed on the gas concentration response curve. The fluctuation amplitude of gas concentration with flow rate switching within each modulation cycle is extracted to construct flow rate sensitive component data. A baseline value of gas concentration within each modulation cycle is extracted to construct flow rate insensitive component data. The flow rate sensitive component data characterizes the free volatile components on the surface of the thin-layer sample, and the flow rate insensitive component data characterizes the diffused release components inside the thin-layer sample.

[0025] S5. Perform performance evaluation steps. Select a specific temperature range and calculate the ratio of the flow velocity insensitive component data to the flow velocity sensitive component data to obtain a swelling evaluation index. Compare the swelling evaluation index with a preset standard threshold, and determine the degree of rubber powder swelling of the modified asphalt sample based on the comparison result. Alternatively, calculate the degree of variation of the flow velocity sensitive component data between different sampling points to determine the uniformity of rubber powder dispersion of the modified asphalt sample.

[0026] See attached document Figure 2 For step S1, in this embodiment, a detection system including gas path control, temperature control, and signal acquisition functions is constructed. This detection system consists of an inert gas source, a flow control unit, a thermal desorption chamber, a temperature control unit, and a gas detection unit connected sequentially. The thermal desorption chamber, serving as the sample carrier and reaction space, is preferably made of quartz glass or deactivated stainless steel to avoid adsorption of volatile components on the inner wall of the chamber. The thermal desorption chamber is designed with a low dead volume structure, with the internal free space volume generally controlled between 10 ml and 50 ml, ensuring rapid gas replacement during carrier gas flow rate changes, thereby improving the system's dynamic response to flow field changes. The flow control unit is located between the inert gas source and the inlet of the thermal desorption chamber, and can specifically be a digital mass flow controller (MFC). This digital mass flow controller can receive external commands and adjust the instantaneous flow rate of the carrier gas entering the thermal desorption chamber within milliseconds. The temperature control unit is thermally coupled to the pyrolysis chamber to heat the chamber. Specifically, it can employ a resistance heating mantle, infrared heating lamp, or semiconductor cooling heating module, and work with a temperature sensor to achieve closed-loop PID control, ensuring the chamber temperature changes precisely according to a preset heating program. The gas detection unit is located downstream of the pyrolysis chamber's outlet to monitor the composition and concentration of the outflowing gas in real time. This unit can be a photoionization detector, which uses a high-energy ultraviolet lamp to ionize organic gas molecules, generating a current signal proportional to the gas concentration; or a metal-oxide-semiconductor (MOS) sensor array, which uses different gas-sensitive materials to detect changes in the resistance of a specific gas. For scenarios requiring high precision, a flame ionization detector (FID) can also be used.

[0027] After completing the hardware construction of the detection system, standardized sample preparation and loading are carried out to eliminate the influence of differences in the physical morphology of the samples to be tested on the test results, and to ensure that the volatilization process is mainly controlled by the mass transfer characteristics of the material itself. The high-content rubber powder modified asphalt sample to be tested is obtained and placed on a constant temperature heating platform and heated to a fluid state. The heating temperature is usually set at 150 degrees Celsius to 170 degrees Celsius to make the asphalt have sufficient fluidity for sampling, while avoiding excessive temperature that would cause the light components to volatilize prematurely.

[0028] An inert carrier with fixed geometric dimensions is selected, such as a fixed quantity of quartz wool, glass fiber filter paper, or a quartz boat with a fixed bottom area. A quantitative amount of the heated, flowing modified asphalt sample is transferred onto the surface of the inert carrier. Using a scraper or relying on natural leveling at high temperature, the sample is uniformly coated onto the inert carrier, forming a thin-layer sample with uniform thickness. The thickness of the thin-layer sample is controlled to be less than 1 mm, preferably around 0.5 mm. This thin-layer preparation method minimizes the thermal conductivity gradient within the asphalt layer, allowing the sample temperature to closely follow changes in ambient temperature. Simultaneously, the thin-layer structure shortens the diffusion path of volatile molecules from deep within the liquid phase to the gas-liquid interface, enabling the detection signal to more sensitively reflect the exchange process at the gas-liquid interface, rather than being limited by the mass transfer resistance within the liquid phase. The sample thickness can be determined through calculation, based on the sample mass. Asphalt density and the coating area of ​​the inert carrier According to the formula Estimate and control the coating thickness.

[0029] After sample preparation, the inert carrier containing the thin-layer sample is quickly placed into the sample position of the thermal desorption chamber, and the chamber is immediately sealed. The flow control unit is activated to control the inert carrier gas (such as high-purity nitrogen or helium) to be introduced into the thermal desorption chamber at a constant low flow rate for pre-purging of the chamber. The pre-purging process typically lasts for 1 to 3 minutes. This pre-purging process is used to replace the ambient air in the chamber, remove oxygen and interference from volatile organic compounds in the background, and create an oxygen-free inert detection atmosphere to prevent unexpected oxidation of the asphalt during subsequent heating. After purging, the system is in standby mode, ready to execute the subsequent thermal-fluid coupling excitation procedure. The airtightness checks of the various components of the detection system and the insulation and heat tracing of the connecting pipelines are standard procedures in this field and will not be described in detail here.

[0030] In step S2, after the detection system is in a ready state, the non-equilibrium thermal-fluid coupling excitation procedure is started to simultaneously apply a temperature field that changes linearly with time and a flow field that changes periodically with time to the thin-layer sample in the detection chamber, thereby constructing a dynamic mass transfer perturbation environment.

[0031] The controller sends a command to the temperature control unit to execute a linear programmed temperature increase operation, controlling the temperature of the detection chamber from the initial temperature. At a constant heating rate Continue to rise until the termination temperature Starting temperature The temperature is typically set between 60 and 80 degrees Celsius. This temperature range is higher than ambient room temperature and effectively removes adsorbed water interference from the sample surface, while not triggering the volatilization of light components in the base asphalt. (Termination temperature) The temperature is typically set between 180 and 200 degrees Celsius. This temperature range covers the actual production and application temperature range of modified asphalt, ensuring that the release characteristics of the material in high-temperature application environments are fully activated, and the heating rate is optimal. Setting the temperature to 5 to 20 degrees Celsius per minute, this non-equilibrium continuous heating method can provide a continuously increasing thermal driving force, forcing volatile components with different binding energies to overcome energy barriers and escape from the asphalt matrix in sequence.

[0032] Throughout the entire temperature rise process, the controller synchronously sends commands to the flow control unit to perform periodic modulation of the carrier gas flow rate. The carrier gas flow rate entering the detection chamber is controlled according to a preset waveform at the first flow rate value. Second flow rate value The alternating switching between these states creates pulsed or square-wave flow field disturbances. First flow velocity value. Set to a high-flow-rate purging state, such as 100 ml / min to 500 ml / min. At this flow rate, the gas replacement rate in the chamber is fast, and the hydrodynamic boundary layer thickness at the gas-liquid interface is reduced. (Second flow rate value) Set to a low-flow-rate enrichment state, such as 0 mL / min (flow stopped) to 50 mL / min. At this flow rate, the airflow in the chamber is gentle, the boundary layer thickness at the gas-liquid interface increases, and the volatilized gas molecules tend to accumulate in the headspace of the chamber, defining a complete modulation cycle. The duration is 10 to 60 seconds, and the ratio of high flow rate to low flow rate is fixed within each cycle, for example, 50% each.

[0033] This thermo-fluid coupling excitation is used to screen different mass transfer control processes by utilizing changes in the fluid dynamics state. For light components free on the asphalt surface, the evaporation rate is mainly controlled by the convective mass transfer coefficient at the gas-liquid interface, i.e., affected by the boundary layer thickness; when the flow velocity changes from... Switch to As the boundary layer thins and the mass transfer coefficient increases, the volatility of the surface free components rises sharply, exhibiting flow rate sensitivity. Conversely, for swollen components that have penetrated into the rubber powder, the release process is mainly limited by the diffusion rate of molecules within the rubber crosslinking network and the asphalt paste. This internal diffusion process is slow and is not directly affected by the external gas phase flow rate; therefore, even if the external flow rate changes drastically, its release flux remains relatively stable, exhibiting flow rate insensitivity.

[0034] For step S3, while the non-equilibrium thermal-fluid coupling excitation procedure is being executed, the gas detection unit enters a real-time monitoring state and continuously samples and analyzes the carrier gas flowing out of the thermal desorption chamber. The core sensor in the gas detection unit, such as the photoionization detector (PID), scans the gas passing through its detection chamber at a fixed high sampling frequency. The sampling frequency is usually set to 1 Hz to 10 Hz, that is, 1 to 10 data points are collected per second. The selection of this sampling frequency is used to ensure that the transient change characteristics of gas concentration during the rapid switching of carrier gas flow rate can be fully captured, and to prevent waveform distortion or peak loss due to undersampling.

[0035] The data acquisition module synchronously records four key parameters: sampling time, real-time temperature of the detection chamber, current carrier gas flow rate (marked as high or low flow rate), and the response signal intensity of the gas sensor. The response signal intensity is usually characterized in the form of voltage (volts) or concentration (parts per million, ppm), and its value reflects the instantaneous concentration of total volatile organic compounds in the mixed gas at the current moment. For systems equipped with sensor arrays, the data acquisition module will simultaneously record signals from multiple channels, corresponding to the concentrations of components with different chemical properties (such as aliphatic hydrocarbons, aromatic hydrocarbons, or oxygen-containing derivatives).

[0036] As the heating process progresses and the carrier gas flow rate is periodically modulated, the acquired raw signal exhibits characteristic dynamic waveforms. From a macroscopic perspective, as the chamber temperature increases from the initial stage to the end, the total release of volatile components from the modified asphalt gradually increases, resulting in a signal baseline that first rises and then falls, forming an overall envelope shape that reflects the material's heat release profile. From a microscopic perspective, superimposed on this overall envelope is a pulse waveform that oscillates synchronously with the flow rate modulation period. When the carrier gas flow rate is in a low-flow-rate enrichment state, due to the reduced dilution effect and the accumulation of volatiles in the chamber headspace, the sensor typically records relatively high concentration peaks. When the carrier gas flow rate switches to a high-flow-rate purging state, due to the strong carrier gas dilution effect, the concentration values ​​recorded by the sensor rapidly decrease, containing dynamic response information of volatile components to flow field disturbances, providing the raw data basis for subsequent signal decoupling.

[0037] After obtaining the original dynamic gas concentration response curve, the signal processing unit executes a decoupling algorithm to separate the mixed signal into a velocity-sensitive component and a velocity-insensitive component. This is based on key physical assumptions: the free light components existing on the surface of modified asphalt have a volatilization rate mainly controlled by the convective mass transfer at the gas-liquid interface, thus exhibiting high sensitivity to changes in the carrier gas flow rate; while the swollen components existing inside the rubber powder particles have a release rate controlled by diffusion within the solid-liquid phase, exhibiting insensitivity to changes in the external carrier gas flow rate.

[0038] The signal processing unit first processes the acquired raw signal. Periodic segmentation is performed, dividing the continuous time series data into several independent processing units based on the modulation frequency of the carrier gas velocity. Each processing unit corresponds to a complete modulation period. In each modulation cycle Within the range, the response signal intervals corresponding to the high-velocity purging stage and the low-velocity enrichment stage were identified. The quasi-steady-state signal value at the end of the high-velocity stage was extracted and denoted as... Extract the quasi-steady-state signal value at the end of the low-velocity stage, and denote it as... Simultaneously record the average detection temperature corresponding to this cycle. .

[0039] Based on the extracted feature values, the flow velocity sensitive component is calculated. The velocity-sensitive component is defined as the signal fluctuation amplitude after velocity normalization within the modulation period. This velocity-sensitive component quantifies the degree of change in the intensity of volatile component release when external flow field conditions change. The specific calculation logic is as follows: ; in, Indicates the first Each modulation period corresponds to an average temperature of The calculation results at that time The average temperature over a period of time. For correction factors, The first flow velocity value, This is the second flow velocity value. For flow ratio correction factor; numerical value The magnitude of this flux depends primarily on the diffusion flux within the material and has little correlation with the surface flow field state; numerical values... The larger the value, the more likely the volatiles at that temperature are mainly derived from the swollen oil or pyrolysis products inside the rubber powder, which are bound components.

[0040] Perform the curve reconstruction step, using temperature The x-axis represents the calculated values. and Using the vertical axis as the ordinate, spline interpolation or polynomial fitting methods are employed to connect discrete data points into continuous "flow velocity sensitivity characteristic curves" and "flow velocity insensitivity characteristic curves." These two curves constitute the fingerprint spectrum of the modified asphalt sample, intuitively demonstrating the release patterns of free and swollen components with temperature changes. This allows for the mathematical separation of the component states in complex mixtures without the need for physical extraction or separation operations.

[0041] Obtain the reconstructed flow velocity sensitivity characteristic curve and flow velocity insensitivity characteristic curve Subsequently, the data analysis module is used to calculate quantitative performance evaluation indicators to comprehensively judge the swelling degree, dispersion uniformity and aging state of modified asphalt, which is used to transform the complex fingerprint spectrum into intuitive quality grade conclusions.

[0042] See attached document Figure 3 To evaluate the degree of swelling development of rubber powder in modified asphalt, a swelling efficiency index was constructed, and a simulated construction temperature range for modified asphalt was selected. As a feature evaluation window, for example, setting It is 160 degrees Celsius. The temperature range is 180 degrees Celsius. Within this temperature range, ideal modified asphalt should have low surface free oil content and stable internal release flux. The ratio of the cumulative velocity insensitivity component to the total cumulative volatile matter is calculated using the following formula: ; in, For the intensity of the flow velocity sensitive component, The intensity of the insensitive component of the flow velocity. Indicates temperature. This represents the swelling efficiency index. Calculated... The value reflects the degree to which volatile components are bound by the adhesive particles at the construction temperature. The calculated value... Value and preset swelling threshold Perform a comparison. If... (For example, 80%) indicates that the modified asphalt sample has good swelling development and the rubber powder is tightly bonded to the base asphalt; if The sample was determined to have insufficient swelling and a large amount of unabsorbed free light components, which may lead to oil seepage or decreased adhesion on the road surface.

[0043] To evaluate the uniformity of rubber powder dispersion in modified asphalt, a multi-point sampling variation analysis method was used. Samples were collected from different locations or at different times for the same batch of modified asphalt products. One (e.g.) Parallel samples were subjected to the aforementioned detection and decoupling steps to obtain... Group flow velocity sensitivity characteristic curves. Extract the characteristic peak values ​​from each group of curves. (in ), and calculate the coefficient of variation of this set of peaks. : ; in, for The arithmetic mean of the characteristic peaks of each sample. This represents the number of parallel samples collected. Characteristic peak value Sample number index, coefficient of variation This directly reflects the consistency of the distribution of rubber powder in the asphalt matrix. With the preset uniformity threshold Perform a comparison; if The modified asphalt in this batch was determined to be uniformly dispersed with no obvious segregation. The product batch was determined to have issues with adhesive powder agglomeration or sedimentation segregation.

[0044] For the aging state and pyrolysis risk assessment of modified asphalt, the main basis is the morphological characteristics of the flow velocity insensitivity characteristic curve in the high-temperature range. The slope change of the flow velocity insensitivity characteristic curve in the range above normal construction temperature (e.g., above 180 degrees Celsius) is observed. If the curve shows a monotonically stable or decreasing trend in this high-temperature range, it indicates good thermal stability of the material. If the curve shows a double upward peak or a sudden change point with a sharp increase in slope in the region above 180 degrees Celsius, and the flow velocity sensitive component corresponding to this change remains low, then the intensity of this change is defined as the aging factor. This phenomenon indicates that thermal decomposition of polymer segments occurred within the rubber powder particles, generating new small molecular fragments which were slowly released in a diffusion-controlled manner. This suggests that the modified asphalt has undergone excessive thermal history, leading to irreversible degradation of the rubber powder modifier. During the assessment, if aging factors are detected... If the preset safety threshold is exceeded, the modified asphalt is deemed to have a risk of aging and failure and should not be used further.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for testing the performance of modified asphalt based on the release characteristics of volatile components, characterized in that, Includes the following steps: S1. The modified asphalt sample to be tested is coated on the surface of an inert carrier to form a thin layer sample, and the inert carrier carrying the thin layer sample is placed into a sealed testing chamber with temperature control and gas flow control functions. S2. Control the temperature of the sealed detection chamber to rise linearly from the starting temperature to the ending temperature at a preset heating rate, and control the carrier gas flow rate entering the sealed detection chamber to alternate between the first flow rate value and the second flow rate value according to a preset modulation period to construct a dynamic mass transfer environment. S3. Continuously detect the gas concentration at the outlet of the sealed detection chamber using a gas detection device, and generate a gas concentration response curve that exhibits fluctuating characteristics synchronously with the switching of carrier gas flow rate. S4. Analyze the gas concentration response curve, extract the fluctuation amplitude of the flow rate switching in each modulation cycle to construct the flow rate sensitive component, and extract the concentration reference value in each modulation cycle to construct the flow rate insensitive component. The flow rate sensitive component represents the free volatile components on the sample surface, and the flow rate insensitive component represents the diffused release components inside the sample. S5. Calculate the swelling evaluation index using the numerical relationship between the flow rate insensitive component and the flow rate sensitive component in a specific temperature range to determine the degree of swelling of the adhesive powder, or use the degree of difference between the flow rate sensitive components generated at different sampling points to determine the uniformity of adhesive powder dispersion.

2. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, In step S2, constructing the dynamic mass transfer environment includes: For thermal field control, the initial temperature is set to 60 degrees Celsius to 80 degrees Celsius, the final temperature is set to 180 degrees Celsius to 200 degrees Celsius, and the heating rate is set to 5 degrees Celsius to 20 degrees Celsius per minute; For flow field control, the modulation period of the carrier gas flow rate is set to 10 seconds to 60 seconds, the first flow rate value is set to 100 ml / min to 500 ml / min, and the second flow rate value is set to 0 ml / min to 50 ml / min.

3. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, In step S4, the step of constructing the flow rate sensitive component further includes: Within each modulation cycle, the signal value corresponding to the end of the high flow rate phase of the first flow rate value and the signal value corresponding to the end of the low flow rate phase of the second flow rate value are identified. Calculate the absolute value of the difference between the signal value at the end of the low flow rate phase and the signal value at the end of the high flow rate phase after high-low flow rate ratio correction, and use the absolute value as the flow rate sensitive component value corresponding to the current modulation period.

4. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, In step S4, the step of constructing the flow velocity insensitivity component further includes: Based on the signal values ​​at the end of the low flow rate phase and the end of the high flow rate phase, the arithmetic mean of the signal value at the end of the low flow rate phase and the signal value at the end of the high flow rate phase after correction by the high-low flow rate ratio is calculated, and the arithmetic mean is used as the flow rate insensitivity component value corresponding to the current modulation period.

5. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, In step S5, the step of determining the degree of swelling of the adhesive powder further includes: Select a preset simulated construction temperature range, calculate the percentage of the integral area of ​​the insensitive flow velocity component within the construction temperature range to the sum of the integral areas of the insensitive flow velocity component and the integral areas of the sensitive flow velocity component, and obtain the swelling efficiency index. The swelling efficiency index is compared with a preset swelling threshold. When the swelling efficiency index is greater than the preset swelling threshold, the rubber powder swelling development of the modified asphalt sample is deemed qualified.

6. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, In step S5, the step of determining the uniformity of the adhesive powder dispersion further includes: Multiple samples were taken from the same batch of modified asphalt products and steps S1 to S4 were performed respectively to obtain the flow rate sensitive component curves of each of the multiple parallel samples. Extract the characteristic peaks from the flow rate sensitive component curve and calculate the coefficient of variation of the characteristic peaks; The coefficient of variation is compared with a preset uniformity threshold. When the coefficient of variation is less than the uniformity threshold, the rubber powder of the modified asphalt sample is determined to be uniformly dispersed.

7. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, The S5 also includes an evaluation of the aging state of modified asphalt, further including: On the continuous curve generated corresponding to the insensitive component of the flow velocity, the slope variation characteristics in the high temperature range above 180 degrees Celsius were observed. When the generated continuous curve shows a sudden change point with a sharp increase in slope or a second rising peak in the high temperature range, and the corresponding flow rate sensitive component remains at a low level, it is determined that the modified asphalt sample has a risk of aging failure.

8. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, In step S1, the coating thickness of the thin-layer sample is between 0.5 mm and 1 mm to eliminate the thermal conductivity gradient inside the sample. The sealed detection chamber is made of an inert material that does not adsorb organic volatiles, and the internal free space volume is between 10 ml and 50 ml.

9. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, In step S3, the gas detection device is a photoionization detector or a metal oxide semiconductor sensor array, and the data sampling frequency of the gas concentration response curve is set to 1 Hz to 10 Hz to fully record the transient waveform generated by the flow rate switching.

10. The method for testing the performance of modified asphalt based on the release characteristics of volatile components according to claim 1, characterized in that, S1 further includes: Inert gas at a constant flow rate is introduced into the sealed detection chamber and maintained for 1 to 3 minutes; The inert gas is used to replace the ambient air in the sealed detection chamber to provide an oxygen-free baseline.

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