Method and system for determining construction window of steel slag asphalt mixture based on thermal conductivity characteristics

Abstract

This invention discloses a method and system for determining the construction window of steel slag asphalt mixture based on its thermal conductivity, belonging to the field of road engineering technology. The method includes: determining the steel slag content and optimal asphalt content of the steel slag asphalt mixture; performing a temperature compaction test on the steel slag asphalt mixture to obtain the minimum allowable compaction temperature; determining the thermal conductivity and specific heat capacity of the steel slag asphalt mixture based on the mix proportion, and constructing a thermodynamic simulation model incorporating the thermal conductivity and specific heat capacity of the steel slag asphalt mixture; acquiring real-time environmental parameters and real-time temperature field data of the underlying layer, inputting them into the thermodynamic simulation model, and predicting the cooling curve; extracting the time point in the cooling curve where the temperature drops to the minimum allowable compaction temperature, and determining the effective construction time window based on the paving start time. This invention achieves scientific and dynamic prediction of the construction time window, significantly improving the compaction quality and durability of steel slag asphalt pavement.

Description

Technical Field

[0001] This invention relates to the field of road construction, and in particular to a method and system for determining the construction window of steel slag asphalt mixture based on its thermal conductivity. Background Technology

[0002] Steel slag is a slag discharged during the smelting process in converters, electric furnaces, and refining furnaces. It is formed from impurities in the metal raw materials, fluxes, and furnace linings, and is mainly composed of silicates, ferrates, and oxides. It possesses stable performance, controllable quality, good stability, uniform particle size, and high wear resistance, making it a high-quality road construction aggregate. Using steel slag in asphalt pavement can effectively reduce costs and achieve high-value utilization of industrial solid waste.

[0003] However, because the thermal conductivity of steel slag is much higher than that of conventional road stone (basalt, diabase, limestone, etc.), it has the characteristics of rapid heat absorption and rapid cooling, which makes temperature control more difficult during the construction of steel slag asphalt pavement.

[0004] However, current construction temperature control measures do not address the high thermal conductivity of steel slag materials, nor do they provide information on the construction time window for steel slag asphalt mixtures. This leads to a series of problems, such as excessively high or low temperatures in steel slag asphalt mixtures, which in turn affect the compaction quality of steel slag asphalt pavements and reduce their overall service life and performance.

[0005] In response to the aforementioned problems of imprecise temperature control and significant disconnect between the construction environment and the actual construction process during the construction of steel slag asphalt pavement, this paper addresses these issues. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for determining the construction window of steel slag asphalt mixture based on its thermal conductivity, so as to at least solve the problems of imprecise temperature control and large disconnect between the construction environment and the existing technology.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for determining the construction window of steel slag asphalt mixture based on its thermal conductivity, the method comprising: Based on the construction design objectives of the target physical project, determine the steel slag content and the optimal asphalt content of the steel slag asphalt mixture. Based on the optimal asphalt content, a temperature compaction test was conducted on the steel slag asphalt mixture to obtain the minimum allowable compaction temperature of the steel slag asphalt mixture. Extract the mix proportion of steel slag asphalt mixture, determine the thermal conductivity and specific heat capacity of steel slag asphalt mixture based on the mix proportion, and construct a thermodynamic simulation model that includes the thermal conductivity and specific heat capacity of steel slag asphalt mixture. The real-time environmental parameters and the real-time temperature field data of the underlying layer of the target project are obtained on the construction day. The real-time environmental parameters and the real-time temperature field data of the underlying layer are input into the thermodynamic simulation model to predict the cooling curve that characterizes the core temperature of the steel slag asphalt mixture layer over time. Extract the time point in the cooling curve where the temperature drops to the minimum allowable compaction temperature, and determine the effective construction time window based on the start time of paving.

[0008] Preferably, a thermodynamic simulation model is constructed that includes the thermal conductivity and specific heat capacity of steel slag asphalt mixture, comprising: Construct an initial thermodynamic simulation model that includes thermal conductivity and specific heat capacity; Obtain environmental parameters of the trial section, the initial temperature field of the underlying layer, and the measured cooling data after the mixture is laid; Based on the environmental parameters of the trial section, the initial temperature field of the underlying layer, and the measured cooling data after the mixture was laid, the initial thermodynamic simulation model was simulated to obtain the simulated cooling curve. Based on the measured cooling data, a measured cooling curve is generated, and the degree of agreement between the measured cooling curve and the simulated cooling curve is extracted. The initial thermodynamic simulation model is then adjusted based on the degree of agreement to obtain a prototype of the thermodynamic simulation model. Acquire case data, use the case data to simulate and verify the prototype of the thermodynamic simulation model, and obtain the final thermodynamic simulation model.

[0009] Preferably, a temperature compaction test is performed on the steel slag asphalt mixture, including: At the optimal bitumen content, specimens were molded at multiple preset temperature points, the porosity of the specimens was tested, and temperature-porosity relationship curves were generated. Based on the preset construction quality conditions, determine the horizontal line of the upper limit of porosity in the coordinate system of the temperature-porosity relationship curve; Extract the intersection of the temperature-voidity relationship curve and the horizontal line, and take the temperature value corresponding to the intersection as the minimum allowable compaction temperature of the steel slag asphalt mixture.

[0010] Preferably, determining the specific heat capacity of steel slag asphalt mixture includes: Obtain the mass fraction and specific heat capacity of each component material in the steel slag asphalt mixture; The specific heat capacity of steel slag asphalt mixture is generated by weighted summation of the mass fraction and specific heat capacity of each component material.

[0011] Preferably, determining the thermal conductivity of steel slag asphalt mixture includes: To obtain the volume fraction and thermal conductivity of each aggregate component in steel slag asphalt mixture; The thermal conductivity of the aggregate skeleton of steel slag asphalt mixture is determined based on the volume fraction and thermal conductivity of each aggregate component. The volume fraction and thermal conductivity of asphalt and air were obtained, and the thermal conductivity of the aggregate skeleton was combined to determine the thermal conductivity of the steel slag asphalt mixture.

[0012] Preferably, the thermodynamic simulation model includes a natural environment domain for simulating airflow and solar radiation, a steel slag asphalt mixture layer containing thermal conductivity and specific heat capacity, and a subgrade structural domain for simulating heat absorption by the subgrade.

[0013] Preferably, the method further includes: Within the effective construction time window, a quantitative construction process plan is generated, including temperature control for mixing and transportation, speed control for paving operations, and compaction process parameters. The compaction process parameters include at least the roller configuration, the start and end times of compaction at each stage, and the compaction speed and number of passes.

[0014] Secondly, the present invention also provides a system for determining the construction window of steel slag asphalt mixture based on thermal conductivity, for implementing the above-mentioned method for determining the construction window of steel slag asphalt mixture based on thermal conductivity, the system comprising: The dosage calculation module is used to determine the steel slag content and optimal asphalt content of steel slag asphalt mixture based on the construction design objectives of the target physical project. The temperature calculation module is used to perform temperature compaction tests on steel slag asphalt mixtures based on the optimal asphalt content, and to obtain the minimum allowable compaction temperature of the steel slag asphalt mixtures. The model building module is used to extract the mix proportion of steel slag asphalt mixture, determine the thermal conductivity and specific heat capacity of steel slag asphalt mixture based on the mix proportion, and build a thermodynamic simulation model containing the thermal conductivity and specific heat capacity of steel slag asphalt mixture. The temperature prediction module is used to obtain real-time environmental parameters and real-time temperature field data of the underlying layer of the target project on the construction day. The real-time environmental parameters and real-time temperature field data of the underlying layer are input into the thermodynamic simulation model to predict the cooling curve that characterizes the core temperature of the steel slag asphalt mixture layer over time. The window determination module is used to extract the time point in the cooling curve when the temperature drops to the minimum allowable compaction temperature, and determine the effective construction time window based on the start time of paving.

[0015] Thirdly, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method for determining the construction window of steel slag asphalt mixture based on thermal conductivity.

[0016] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method for determining the construction window of steel slag asphalt mixture based on thermal conductivity.

[0017] Compared with the prior art, the present invention has the following significant advantages: 1. Scientific nature and precision: Starting from the high thermal conductivity of steel slag material, this invention deeply integrates indoor material testing with thermodynamic process simulation (CFD cooling simulation) under field conditions, realizing quantitative analysis and accurate prediction of dynamic changes in the construction temperature field. It completely changes the extensive temperature control mode that relies on experience, clarifies the optimal construction window period for steel slag asphalt mixture paving, and provides construction guidance based on this window period to obtain a pavement that meets engineering standards.

[0018] 2. Direct Construction Guidance: The core output of this method is a clearly defined "construction time window," which is intuitive and operable. Based on this, the construction team can accurately calculate and arrange the quantity of compaction equipment, rolling speed, number of passes, and travel routes, optimizing construction organization and ensuring that all compaction processes are completed within the effective compaction temperature range of the mixture, thus guaranteeing compaction quality throughout the process.

[0019] 3. Ensure project quality and lifespan: By precisely controlling the compaction temperature and time, it can effectively avoid insufficient compaction of steel slag asphalt mixture due to excessively low temperature or asphalt aging caused by excessively high temperature, significantly improving the initial density, uniformity, impermeability and durability of the pavement, thereby extending the service life of the pavement. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method for determining the construction window of steel slag asphalt mixture based on thermal conductivity according to the present invention. Figure 2 This is a schematic diagram of the gradation design composition of the present invention; Figure 3 This is a schematic diagram of the Marshall test results of the present invention; Figure 4 This is a schematic diagram of the Marshall test results for the SMA-13 ​​of the present invention; Figure 5 This is a schematic diagram of the asphalt mixture performance test results of the present invention; Figure 6 This is a schematic diagram of the temperature compaction curve of the present invention; Figure 7 This is a schematic diagram of the geometric model of the present invention; Figure 8 This is a schematic diagram of the initial temperature field of the underlying layer of the present invention; Figure 9 This is a schematic diagram of the measured cooling curve of the present invention; Figure 10 This is a schematic diagram of the simulated cooling curve of the present invention; Figure 11 This is a schematic diagram showing the superposition and comparison of the simulated cooling curve and the measured cooling curve of the present invention; Figure 12 This is a schematic diagram of the predicted cooling curve of the present invention; Figure 13 This is a schematic diagram of the parameters in the corresponding CFD for the three construction nodes of the present invention; Figure 14 This is a block diagram of the system for determining the construction window of steel slag asphalt mixture based on thermal conductivity, as per the present invention. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0022] Example 1 like Figure 1 As shown in the figure, this embodiment provides a method for determining the construction window of steel slag asphalt mixture based on thermal conductivity, the method including steps S1 to S5.

[0023] Step S1: Determine the steel slag content and optimal asphalt content of the steel slag asphalt mixture based on the construction design objectives of the target physical project.

[0024] Specifically, the construction design objectives of the target physical project refer to the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40) and the local standard "Technical Specification for Application of Steel Slag Asphalt Pavement", etc., and carry out SMA-13 ​​gradation design.

[0025] When designing the aggregate gradation, it is necessary to fully consider the characteristic that the apparent density of steel slag is much greater than that of conventional aggregates. The volumetric method is used for gradation calculation and adjustment to ensure the formation of the skeleton structure. In this embodiment, steel slag in the 6-11mm range is used to partially replace natural crushed stone of the same range, while diabase is still used in the 11-18mm range. Limestone is used for fine aggregates, and limestone mineral powder filler is limestone mineral powder with 0.3% lignin fiber added externally.

[0026] Further Marshall tests determined the optimal asphalt-aggregate ratio (OAC) for this production mix to be 5.80%. The optimal OAC is used to characterize the optimal asphalt content. For relevant design gradation and Marshall test results, please refer to [link to relevant documentation]. Figures 2-5 All indicators meet the requirements of the standards.

[0027] Step S2: Perform a temperature compaction test on the steel slag asphalt mixture based on the optimal asphalt content to obtain the minimum allowable compaction temperature of the steel slag asphalt mixture.

[0028] In this embodiment, a temperature compaction test is performed on the steel slag asphalt mixture, including: molding specimens at multiple preset temperature points under the optimal asphalt content, testing the porosity of the specimens, and generating a temperature-porosity relationship curve; determining the upper limit of porosity on the coordinate system of the temperature-porosity relationship curve according to preset construction quality conditions; extracting the intersection of the temperature-porosity relationship curve and the horizontal line, and taking the temperature value corresponding to the intersection as the minimum allowable compaction temperature of the steel slag asphalt mixture.

[0029] Specifically, the experimental design involved precisely setting and controlling eight compaction temperature points at the determined optimal asphalt-aggregate ratio of 5.80%: 170℃, 165℃, 160℃, 155℃, 150℃, 145℃, 140℃, and 135℃. This temperature range covered and was slightly wider than the expected temperature range encountered during construction.

[0030] Specimen molding and testing: Following the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG3410-2025), the mixture was mixed at each temperature point, and Marshall specimens were formed by compacting both sides 75 times. After the specimens had completely cooled, their bulk density and theoretical maximum relative density were measured.

[0031] Data Analysis: Calculate the porosity (VV) of the molded specimen at each temperature point. Plot a scatter plot with compaction temperature (°C) on the x-axis and porosity (%) on the y-axis, and fit a smooth temperature-compaction curve, as shown below. Figure 6 As shown.

[0032] Determine the minimum allowable compaction temperature: According to the design documents and construction specifications of this project, the on-site compaction degree must not be less than 98% of the Marshall standard density (i.e., the aforementioned preset construction quality conditions). Corresponding to the mixture prepared in this embodiment, this translates to an upper limit of porosity of approximately 6.0%. Figure 6 On the temperature-compaction curve shown, draw a horizontal line parallel to the horizontal axis, corresponding to a porosity of 6.0%. The temperature value corresponding to the intersection of this horizontal line and the curve is the minimum allowable compaction temperature. In this example, the minimum allowable compaction temperature is approximately 140℃. This means that, to ensure compaction quality, the core temperature of the steel slag asphalt mixture during the compaction process should not be lower than 140℃.

[0033] Step S3: Extract the mix proportion of steel slag asphalt mixture, determine the thermal conductivity and specific heat capacity of steel slag asphalt mixture based on the mix proportion, and construct a thermodynamic simulation model (CFD) that includes the thermal conductivity and specific heat capacity of steel slag asphalt mixture.

[0034] Specifically, in step S1, the final production mix proportion of the steel slag asphalt mixture is determined. Based on the mix proportion, the mass fraction (w) and volume fraction (v) of each component material (steel slag, diabase, limestone, mineral powder, and asphalt) are obtained. Then, through material handbooks or laboratory tests, the specific heat capacity (c, unit: J / (kg·℃)) and thermal conductivity (λ, unit: W / (m·℃)) of each component within the relevant temperature range are obtained. Among these, the thermal conductivity of steel slag is significantly higher than that of other aggregates, which is the key to the calculation.

[0035] In this embodiment, determining the specific heat capacity of the steel slag asphalt mixture includes: obtaining the mass fraction and specific heat capacity of each component material of the steel slag asphalt mixture; and performing a weighted summation of the mass fraction and specific heat capacity of each component material to generate the specific heat capacity of the steel slag asphalt mixture.

[0036] Among them, the specific heat capacity of steel slag asphalt mixture is calculated ( The calculation is performed using formula (1), which is a weighted average based on mass fraction: (1) In equation (1), w 钢渣 w 粗 w 细 w 矿粉 w 沥青 The corresponding mass fractions (%) of steel slag, coarse aggregate, fine aggregate, mineral powder, and asphalt, respectively; c 钢渣 c 粗 c 细 c 矿粉 c 沥青 The specific heat capacities [J / (kg·℃)] of steel slag, coarse aggregate, fine aggregate, mineral powder, and asphalt, respectively.

[0037] In this embodiment, determining the thermal conductivity of the steel slag asphalt mixture includes: obtaining the volume fraction and thermal conductivity of each aggregate component of the steel slag asphalt mixture; determining the thermal conductivity of the aggregate skeleton of the steel slag asphalt mixture based on the volume fraction and thermal conductivity of each aggregate component; obtaining the volume fraction and thermal conductivity of asphalt and air, and combining them with the thermal conductivity of the aggregate skeleton to determine the thermal conductivity of the steel slag asphalt mixture.

[0038] Specifically, the thermal conductivity of the steel slag asphalt mixture in this embodiment is ( It will be done in two steps: First, based on the volume fraction of each aggregate (steel slag, diabase, limestone, and mineral powder), the thermal conductivity of the aggregate in the mixture is calculated using equation (2). : (2) In equation (2), λ 钢渣 , λ粗 , λ 细 , λ 矿粉 These correspond to the thermal conductivity of steel slag, coarse aggregate, fine aggregate, and mineral powder, respectively, in W / (m·℃); v 钢渣 v 粗 v 细 v 矿粉 The corresponding volume fractions (%) of steel slag, coarse aggregate, fine aggregate, and mineral powder are respectively.

[0039] Then, considering the effects of asphalt binder and voids (air), the final thermal conductivity of the entire steel slag asphalt mixture is calculated using equation (3) based on the volume fraction of asphalt and air and their thermal conductivity. : (3) In equation (3), λ 混合料 , λ 空气 , λ 沥青 These correspond to the thermal conductivity of the mixture, air, and asphalt, respectively, in W / (m·℃); v 混合料 v 骨料 v 空气 The corresponding volume fractions (%) of the mixture, aggregate, and air, respectively.

[0040] Through the above calculations, the key material parameters used for thermodynamic simulation (CFD) modeling can be obtained: the specific heat capacity of the mixture (…). ) and the thermal conductivity of the mixture ( ).

[0041] In this embodiment, the steps for constructing a thermodynamic simulation model including the thermal conductivity and specific heat capacity of steel slag asphalt mixture are as follows: Constructing an initial thermodynamic simulation model including thermal conductivity and specific heat capacity; acquiring environmental parameters of the test section, the initial temperature field of the underlying layer, and measured cooling data after the mixture is paved; simulating the initial thermodynamic simulation model based on the environmental parameters of the test section, the initial temperature field of the underlying layer, and the measured cooling data after the mixture is paved, to obtain a simulated cooling curve; generating a measured cooling curve based on the measured cooling data, extracting the degree of agreement between the measured cooling curve and the simulated cooling curve, adjusting the initial thermodynamic simulation model based on the degree of agreement, and obtaining a preliminary thermodynamic simulation model; acquiring case data, and using the case data to simulate and verify the preliminary thermodynamic simulation model, to obtain the final thermodynamic simulation model.

[0042] Therefore, the thermodynamic simulation model in this embodiment includes a natural environment domain for simulating airflow and solar radiation, a steel slag asphalt mixture layer containing thermal conductivity and specific heat capacity, and a subgrade structural domain for simulating heat absorption by the underlying layer. The natural environment domain integrates a solar radiation model to dynamically calculate solar radiation intensity based on the construction location, date, time, and cloud cover information.

[0043] Specifically, the initial thermodynamic simulation model in this embodiment is constructed and initially set up as follows: Software platform: CradleCFD2021, a commercial computational fluid dynamics software, was used for modeling and simulation; Geometric models (such as) Figure 7 As shown), create a 1:1 scale 3D model, containing the following three areas: 1. Upper layer (natural environment domain): Dimensions: 1000mm (length) × 500mm (width) × 500mm (height). Simulates airflow and solar radiation, with one side designated as the velocity inlet (defining wind speed and air temperature) and the other side as the pressure outlet.

[0044] 2. Intermediate Layer (Steel Slag Asphalt Mixture Layer): Dimensions 1000mm × 500mm × Hmm. H is the actual paving thickness, 40mm in this example. Assign it the material properties calculated above (density, specific heat capacity of the mixture, etc.). ) and the thermal conductivity of the mixture ( )).

[0045] 3. Lower layer (underlying heat absorption zone): Dimensions 1000mm × 500mm × 100mm. Divide it into 10 sub-layers, each 10mm thick, to more accurately simulate vertical heat conduction. Assign it the initial thermophysical properties of the existing pavement material (e.g., AC-16).

[0046] Mesh generation: A structured mesh is used to finely divide the asphalt mixture layer and the underlying layer. The mesh size is approximately 100mm×100mm×5mm to balance calculation accuracy and efficiency.

[0047] The boundary conditions and physical model parameters are set as follows: 1. Flow field: Set constant wind speed (e.g., 7.0 m / s) and air temperature (e.g., 15℃) at the entrance of the natural environment domain; 2. Radiation: Activate the solar radiation model, input the latitude and longitude of the construction site (measured temperature data of a steel slag asphalt pavement test section), date, specific time (e.g., 14:00 on August 15, 2025), and cloud cover (refer to local meteorological information), and the software will automatically calculate the solar radiation intensity; 3. Initial conditions: Set the initial uniform temperature of the steel slag asphalt mixture layer to the paving temperature (e.g., 180℃). Set the initial temperature of the underlying layer to a non-uniform field, and input it according to the depth gradient based on measured data (the temperature decreases by a certain number of degrees for every 30mm increase in depth).

[0048] After completing the construction and initial settings of the thermodynamic simulation model, it needs to be corrected, as follows: Measured temperature data of a steel slag asphalt pavement test section, construction date August 15, 2025, with comprehensive monitoring conducted simultaneously during construction: Subgrade temperature field: Before paving, drill holes to a depth of 150mm at the measuring points, and use a digital thermocouple thermometer to measure the temperature at a point every 30mm depth to establish a precise "subgrade initial temperature field," such as... Figure 8 As shown.

[0049] Cooling process of steel slag asphalt mixture: Monitoring begins immediately after paving, mainly monitoring the surface temperature and interlayer interface temperature; Surface temperature: Infrared thermal imagers were used to continuously photograph the road surface, acquiring image sequences of surface temperature changes over time across the entire area. The measured surface cooling curves at the measurement points were then extracted (e.g.,...). Figure 9 (Middle red / blue curve).

[0050] Among them, the interlayer interface temperature: Before paving, armored thermocouple temperature sensors are pre-embedded on the surface of the underlying layer at the measuring points. After paving, the temperature of the contact surface between the steel slag asphalt mixture and the underlying layer is continuously collected to obtain the measured cooling curve of the interface (e.g., Figure 9 (Middle black curve).

[0051] All environmental parameters collected during the trial paving day, the temperature field of the underlying layer, the initial temperature of the mixture, and the thermal conductivity and specific heat capacity of the steel slag asphalt mixture were input into the initial thermodynamic simulation model constructed above. The simulation was run, and the simulated surface cooling curves and simulated interface cooling curves at the same measuring points were output, such as... Figure 10 As shown.

[0052] The simulated cooling curve ( Figure 10 ) and measured cooling curve ( Figure 9 ) to perform superimposed comparison (e.g. Figure 11 As shown). Typically, due to the complexity of the underlying layer's composition, the actual thermophysical properties (specific heat capacity, thermal conductivity) of the underlying layer differ from the manual values, leading to discrepancies between the simulated and measured cooling curves. Therefore, the simulation can be rerun by adjusting the thermal conductivity and specific heat capacity of the underlying layer until the simulated and measured cooling curves show a high degree of agreement in their shapes and values ​​during the main cooling stages. After completing the initial fitting, the obtained data is combined with data from other construction sections (i.e., case data) to compare the simulated and measured cooling curves. Figure 11The model was then validated using field data. This resulted in a reliable "validated CFD model," which was used to obtain the final thermodynamic simulation model incorporating the thermal conductivity and specific heat capacity of the steel slag asphalt mixture.

[0053] Step S4: Obtain the real-time environmental parameters and the real-time temperature field data of the underlying layer of the target entity project on the construction day. Input the real-time environmental parameters and the real-time temperature field data of the underlying layer into the thermodynamic simulation model to predict the cooling curve used to characterize the core temperature of the steel slag asphalt mixture layer over time.

[0054] Specifically, real-time data is collected: the day before construction, boreholes are drilled in the planned construction section to measure the temperature field of the underlying layer, using the same method as in the trial paving stage. On the day of construction, accurate local weather forecasts are obtained to determine the predicted values ​​for temperature, wind speed, and cloud cover during the construction period.

[0055] Run the predictive simulation: Input all the above-mentioned real-time / forecasted environmental parameters, measured subgrade temperature field data, and the planned initial paving temperature of the steel slag asphalt mixture (e.g., 185℃) into the validated CFD model. Run the simulation, and the software will calculate the dynamic temperature field changes of the steel slag asphalt mixture layer from the start of paving under this specific comprehensive working condition.

[0056] Extracting the predicted cooling curve: From the simulation results, extract the curve of the average temperature (i.e., core temperature) of the steel slag asphalt mixture layer in the thickness direction as a function of time, as the predicted cooling curve, such as... Figure 12 As shown.

[0057] Step S5: Extract the time point in the cooling curve when the temperature drops to the minimum allowable compaction temperature, and determine the effective construction time window based on the start time of paving.

[0058] Specifically, in the obtained predicted cooling curve ( Figure 12 Draw a horizontal line parallel to the horizontal axis (time axis) on the time axis, corresponding to the minimum allowable compaction temperature ≈140℃.

[0059] The time coordinate corresponding to the intersection of this horizontal line and the predicted cooling curve is the moment when the core temperature drops to 140℃. Based on the time point read, in this example, this moment is approximately 12 minutes after the paving began.

[0060] Therefore, the effective construction time window is defined as the period from the start of paving (t=0) to the core temperature dropping to 140℃ (t=12min). The window length Δt = 12 minutes. This means that all critical compaction operations must be initiated and completed within this 12-minute period.

[0061] As a further optimization of this embodiment, the method further includes: generating a quantitative construction process scheme within an effective construction time window, including temperature control for mixing and transportation, speed control for paving operations, and compaction process parameters, wherein the compaction process parameters include at least the roller configuration, the start and end times of compaction at each stage, and the compaction speed and number of passes.

[0062] Specifically, based on the tight 12-minute construction window, the following highly targeted construction plan was developed and implemented to ensure effective compaction within the temperature window: Mixing and transportation temperature control: The outlet temperature of the steel slag SMA mixture is increased to 185-190℃ to compensate for rapid heat loss in winter. Transport vehicles are equipped with thickened insulation covers, and heated transport vehicles are used when necessary.

[0063] Paving operation control: Strictly control the paver's travel speed at 2.5m / min to ensure continuous and uniform paving operations, allowing time for subsequent compaction. Preheat the screed to above 120℃ 0.5-1 hour in advance.

[0064] Rolling process optimization: Equipment configuration: During the compaction stage, since it is a single-lane construction, two 13-ton double-drum vibratory rollers should be provided to ensure sufficient compaction capacity and coverage of the work surface.

[0065] Initial compaction (immediate follow-up): The first roller immediately follows the paver, at a distance of no more than 5 meters. A static-then-vibration method is used, meaning static compaction occurs during the first advance, followed by low-amplitude, high-frequency vibration during retreat. Objective: To complete initial compaction within 2-3 minutes after paving, thus initially stabilizing the mixture.

[0066] Secondary compaction (high efficiency): After the initial compaction, secondary compaction is immediately performed by the same roller or a second roller. Vibration mode is used, and the rolling speed is controlled at 4-6 km / h. Based on the window time calculation, 3-4 passes of secondary compaction need to be completed within the following 6-8 minutes to quickly increase the compaction degree to near the standard.

[0067] Final compaction (surface finishing): Before the temperature drops to the critical point, perform one pass of static compaction with a double-drum roller to eliminate wheel tracks and improve smoothness.

[0068] Total number of compaction passes: 1 initial compaction pass + 3-4 intermediate compaction passes + 1 final compaction pass, totaling 4-5 passes. The entire compaction process must be carefully organized, with close coordination between roller turns, to ensure that all final compaction work is completed before the 12th minute.

[0069] Implementation effect verification: After construction was carried out according to the above-mentioned process based on scientific prediction windows, the quality of the project was significantly improved: Appearance quality: The paved section has a uniform and dense surface, with no obvious segregation or compaction marks (such as...). Figure 11 (As shown).

[0070] Compaction degree test: Core samples were taken from boreholes on site, and the compaction degree of the core samples met the design requirement of ≥98%, proving that the compaction operation completed within the prediction window was sufficient and effective.

[0071] Permeability performance: Permeability tests were conducted at randomly selected points, and the results were 60 ml / min and 30 ml / min, respectively, which are far better than the standard requirements, indicating that the pavement has excellent water tightness and durability potential.

[0072] Conclusion: This embodiment fully verifies the scientific nature, accuracy, and engineering applicability of the method of the present invention. By combining material properties, environmental factors, and thermodynamic process simulation, the present invention successfully predicted the short construction window (12 minutes) of steel slag asphalt mixture under specific winter conditions, and based on this, formulated an efficient and precise compaction process, ultimately ensuring construction quality and solving the construction problems caused by the high thermal conductivity of steel slag.

[0073] It should be noted that, in this embodiment, the construction plans for August 4th, August 15th, and November 25th, such as... Figure 13 As shown, the gradation scheme of steel slag asphalt mixture adopts a consistent proportion to ensure the consistency of the thermal properties of the steel slag asphalt mixture. In other embodiments, the gradation scheme of steel slag asphalt mixture can also be modified according to the on-site construction requirements. The corresponding thermal properties of steel slag asphalt mixture can be obtained through calculation formulas and substituted into the CFD model.

[0074] Therefore, this embodiment starts from the high thermal conductivity of steel slag material and deeply integrates indoor material testing (temperature-porosity relationship) with thermodynamic process simulation (CFD cooling simulation) under field conditions. This enables quantitative analysis and accurate prediction of dynamic changes in the construction temperature field, completely changing the extensive temperature control mode that relies on experience. It clarifies the optimal construction window for steel slag asphalt mixture paving and provides construction guidance based on this window to obtain a pavement that meets engineering standards.

[0075] Secondly, this embodiment verifies and corrects the general CFD model using trial paving data, ensuring the model's reliability. This model can flexibly input specific environmental parameters (temperature, wind speed, radiation, underlying layer temperature, etc.) for any construction date, achieving "one prediction per construction condition," and exhibits strong adaptability to complex and variable climate and foundation conditions.

[0076] Furthermore, the core output of this embodiment is a clearly defined "construction time window," which is intuitive and operable. Based on this, the construction party can accurately calculate and arrange the number of compaction equipment, rolling speed, number of passes, and travel routes, optimize the construction organization, and ensure that all compaction processes are completed within the effective compaction temperature range of the mixture, thereby guaranteeing the compaction quality from the process perspective.

[0077] Finally, by precisely controlling the compaction temperature and time, this embodiment can effectively avoid insufficient compaction of steel slag asphalt mixture due to excessively low temperature or asphalt aging caused by excessively high temperature, significantly improving the initial density, uniformity, impermeability and durability of the pavement, thereby extending the service life of the pavement.

[0078] Example 2 like Figure 13 As shown, this embodiment provides a system for determining the construction window of steel slag asphalt mixture based on thermal conductivity, used to implement the method for determining the construction window of steel slag asphalt mixture based on thermal conductivity in Embodiment 1. The system includes: The dosage calculation module is used to determine the steel slag content and optimal asphalt content of steel slag asphalt mixture based on the construction design objectives of the target physical project. The temperature calculation module is used to perform temperature compaction tests on steel slag asphalt mixtures based on the optimal asphalt content, and to obtain the minimum allowable compaction temperature of the steel slag asphalt mixtures. The model building module is used to extract the mix proportion of steel slag asphalt mixture, determine the thermal conductivity and specific heat capacity of steel slag asphalt mixture based on the mix proportion, and build a thermodynamic simulation model containing the thermal conductivity and specific heat capacity of steel slag asphalt mixture. The temperature prediction module is used to obtain real-time environmental parameters and real-time temperature field data of the underlying layer of the target project on the construction day. The real-time environmental parameters and real-time temperature field data of the underlying layer are input into the thermodynamic simulation model to predict the cooling curve that characterizes the core temperature of the steel slag asphalt mixture layer over time. The window determination module is used to extract the time point in the cooling curve when the temperature drops to the minimum allowable compaction temperature, and determine the effective construction time window based on the start time of paving.

[0079] This embodiment also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for determining the construction window of steel slag asphalt mixture based on thermal conductivity in Embodiment 1.

[0080] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for determining the construction window of steel slag asphalt mixture based on thermal conductivity in Embodiment 1.

[0081] This embodiment starts from the high thermal conductivity of steel slag materials and deeply integrates indoor material testing with on-site thermodynamic process simulation (CFD cooling simulation). It achieves quantitative analysis and accurate prediction of dynamic changes in the construction temperature field, completely changing the experience-based, extensive temperature control model. It clearly defines the optimal construction window for steel slag asphalt mixture paving and provides construction guidance based on this window to obtain a pavement that meets engineering standards. The core output of this embodiment is a clearly defined "construction time window," an intuitive and operable indicator. The construction team can use this to accurately calculate and arrange the number of compaction equipment, rolling speed, number of passes, and travel routes, optimizing construction organization and ensuring that all compaction processes are completed within the effective compaction temperature range of the mixture, thus guaranteeing compaction quality throughout the process. By precisely controlling compaction temperature and time, this embodiment effectively avoids insufficient compaction due to excessively low temperatures or asphalt aging caused by excessively high temperatures in steel slag asphalt mixtures, significantly improving the initial density, uniformity, impermeability, and durability of the pavement, thereby extending its service life.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and all such changes, modifications, substitutions, and variations should be considered to fall within the protection scope of the present invention as defined by the appended claims.

Claims

1. A method for determining the construction window of steel slag asphalt mixture based on thermal conductivity, characterized in that, The method includes: Based on the construction design objectives of the target physical project, determine the steel slag content and the optimal asphalt content of the steel slag asphalt mixture. Based on the optimal asphalt content, a temperature compaction test was conducted on the steel slag asphalt mixture to obtain the minimum allowable compaction temperature of the steel slag asphalt mixture. Extract the mix proportion of steel slag asphalt mixture, determine the thermal conductivity and specific heat capacity of steel slag asphalt mixture based on the mix proportion, and construct a thermodynamic simulation model that includes the thermal conductivity and specific heat capacity of steel slag asphalt mixture. The real-time environmental parameters and the real-time temperature field data of the underlying layer of the target project are obtained on the construction day. The real-time environmental parameters and the real-time temperature field data of the underlying layer are input into the thermodynamic simulation model to predict the cooling curve that characterizes the core temperature of the steel slag asphalt mixture layer over time. Extract the time point in the cooling curve where the temperature drops to the minimum allowable compaction temperature, and determine the effective construction time window based on the start time of paving.

2. The method for determining the construction window of steel slag asphalt mixture based on thermal conductivity according to claim 1, characterized in that, A thermodynamic simulation model incorporating the thermal conductivity and specific heat capacity of steel slag asphalt mixture is constructed, including: Construct an initial thermodynamic simulation model that includes thermal conductivity and specific heat capacity; Obtain environmental parameters of the trial section, the initial temperature field of the underlying layer, and the measured cooling data after the mixture is laid; Based on the environmental parameters of the trial section, the initial temperature field of the underlying layer, and the measured cooling data after the mixture was laid, the initial thermodynamic simulation model was simulated to obtain the simulated cooling curve. Based on the measured cooling data, a measured cooling curve is generated, and the degree of agreement between the measured cooling curve and the simulated cooling curve is extracted. The initial thermodynamic simulation model is then adjusted based on the degree of agreement to obtain a prototype of the thermodynamic simulation model. Acquire case data, use the case data to simulate and verify the prototype of the thermodynamic simulation model, and obtain the final thermodynamic simulation model.

3. The method for determining the construction window of steel slag asphalt mixture based on thermal conductivity according to claim 1, characterized in that, Temperature compaction tests were performed on steel slag asphalt mixtures, including: At the optimal bitumen content, specimens were molded at multiple preset temperature points, the porosity of the specimens was tested, and temperature-porosity relationship curves were generated. Based on the preset construction quality conditions, determine the horizontal line of the upper limit of porosity in the coordinate system of the temperature-porosity relationship curve; Extract the intersection of the temperature-voidity relationship curve and the horizontal line, and take the temperature value corresponding to the intersection as the minimum allowable compaction temperature of the steel slag asphalt mixture.

4. The method for determining the construction window of steel slag asphalt mixture based on thermal conductivity according to claim 1, characterized in that, Determining the specific heat capacity of steel slag asphalt mixture includes: Obtain the mass fraction and specific heat capacity of each component material in the steel slag asphalt mixture; The specific heat capacity of steel slag asphalt mixture is generated by weighted summation of the mass fraction and specific heat capacity of each component material.

5. The method for determining the construction window of steel slag asphalt mixture based on thermal conductivity according to claim 1, characterized in that, Determining the thermal conductivity of steel slag asphalt mixtures includes: To obtain the volume fraction and thermal conductivity of each aggregate component in steel slag asphalt mixture; The thermal conductivity of the aggregate skeleton of steel slag asphalt mixture is determined based on the volume fraction and thermal conductivity of each aggregate component. The volume fraction and thermal conductivity of asphalt and air were obtained, and the thermal conductivity of the aggregate skeleton was combined to determine the thermal conductivity of the steel slag asphalt mixture.

6. The method for determining the construction window of steel slag asphalt mixture based on thermal conductivity according to claim 1, characterized in that, The thermodynamic simulation model includes a natural environment domain for simulating airflow and solar radiation, a steel slag asphalt mixture layer containing thermal conductivity and specific heat capacity, and a subgrade structural domain for simulating heat absorption by the subgrade.

7. The method for determining the construction window of steel slag asphalt mixture based on thermal conductivity according to claim 1, characterized in that, The method further includes: Within the effective construction time window, a quantitative construction process plan is generated, including temperature control for mixing and transportation, speed control for paving operations, and compaction process parameters. The compaction process parameters include at least the roller configuration, the start and end times of compaction at each stage, and the compaction speed and number of passes.

8. A system for determining the construction window of steel slag asphalt mixture based on thermal conductivity, used to implement the method for determining the construction window of steel slag asphalt mixture based on thermal conductivity as described in any one of claims 1-7, characterized in that, The system includes: The dosage calculation module is used to determine the steel slag content and optimal asphalt content of steel slag asphalt mixture based on the construction design objectives of the target physical project. The temperature calculation module is used to perform temperature compaction tests on steel slag asphalt mixtures based on the optimal asphalt content, and to obtain the minimum allowable compaction temperature of the steel slag asphalt mixtures. The model building module is used to extract the mix proportion of steel slag asphalt mixture, determine the thermal conductivity and specific heat capacity of steel slag asphalt mixture based on the mix proportion, and build a thermodynamic simulation model containing the thermal conductivity and specific heat capacity of steel slag asphalt mixture. The temperature prediction module is used to obtain real-time environmental parameters and real-time temperature field data of the underlying layer of the target project on the construction day. The real-time environmental parameters and real-time temperature field data of the underlying layer are input into the thermodynamic simulation model to predict the cooling curve that characterizes the core temperature of the steel slag asphalt mixture layer over time. The window determination module is used to extract the time point in the cooling curve when the temperature drops to the minimum allowable compaction temperature, and determine the effective construction time window based on the start time of paving.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method for determining the construction window of steel slag asphalt mixture based on thermal conductivity as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method for determining the construction window of steel slag asphalt mixture based on thermal conductivity as described in any one of claims 1-7.

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