Andesite asphalt mixture and preparation method thereof

Abstract

The invention relates to the technical field of road building materials, in particular to an andesite asphalt mixture and a preparation method thereof.The preparation method comprises the steps that heated andesite coarse aggregate, limestone machine-made sand and mineral filler are put into a stirring machine to be subjected to dry mixing; adding the heated asphalt and the heated surface modifier for wet mixing; in the wet mixing process, it is judged that the andesite asphalt mixture is in a critical wrapping state according to the wrapping uniformity characterization value, and the preset mixing speed of the mixer is increased to respond to the critical wrapping state; after the preset stirring speed is increased, when the contour sharpness characterization value of the andesite asphalt mixture is larger than or equal to the preset contour sharpness characterization value, the preset stirring speed is corrected; and determining a preparation adjustment strategy of the andesite asphalt mixture according to the temperature drop rate of the andesite asphalt mixture when judging that the andesite asphalt mixture is in a non-uniform coating state according to the uniform coating characterization value. The preparation efficiency of the andesite asphalt mixture is improved.

Description

Technical Field

[0001] This invention relates to the field of road construction materials technology, and in particular to an andesite asphalt mixture and its preparation method. Background Technology

[0002] Asphalt mixtures are the primary paving material in modern road engineering, and their performance and cost directly affect the construction quality, service life, and economic benefits of roads. In engineering construction, especially in mountainous and hilly areas with numerous tunnels, projects often have abundant andesite and other neutral rock resources along their routes, or generate large amounts of tunnel debris. If these resources can be sourced locally and processed into asphalt mixture aggregates, the cost of long-distance transportation of raw materials can be significantly reduced, achieving intensive resource utilization and aligning with the principles of green and sustainable development.

[0003] However, andesite, as a typical neutral silica-alumina rock, has an acidic surface chemical property, resulting in generally poor adhesion to commonly used asphalt. Under water erosion, such mixtures are highly susceptible to asphalt film peeling, leading to early road surface defects such as water damage and loosening, severely restricting their safe application in asphalt pavements, especially high-grade highway pavement structures. To improve adhesion, the industry typically uses the addition of anti-stripping agents (such as various amines and lime), but the stability of their effectiveness and the precise control of their dosage remain challenges in practical engineering. On the other hand, the production quality of asphalt mixtures is highly dependent on the stability of the mixing process; the inability to achieve real-time diagnosis and dynamic adjustment of the production process may lead to unstable batch quality or the generation of substandard materials.

[0004] Chinese Patent Application Publication No. CN117142785A discloses a method for preparing andesite recycled aggregate concrete, comprising: 1) crushing waste concrete with a jaw crusher and removing impurities; 2) passing the crushed waste concrete obtained in step 1) through a magnetic separator to remove the scrap iron contained in the original waste concrete; 3) screening the waste concrete obtained in step 2) through a screening machine, and repeating step 1) to crush the waste concrete with larger particle size; 4) pouring the screened waste concrete into water and stirring, cleaning the impurities floating on the water surface, and then taking out the waste concrete and drying it; 5) modifying the waste concrete obtained in step 4); 6) grinding the modified waste concrete in step 5) to obtain the finished recycled aggregate.

[0005] It can be seen that the above technical solutions do not take into account the differentiated heating temperature control of andesite coarse aggregate and asphalt, do not adopt step-by-step mixing, and do not consider the asphalt coating state during the mixing process. As a result, it is difficult for andesite and asphalt to form a uniform coating, and the performance of the mixture fluctuates, thus leading to the problem of poor preparation efficiency of andesite asphalt mixture. Summary of the Invention

[0006] Therefore, the present invention provides an andesite asphalt mixture and its preparation method to overcome the problems in the prior art that do not consider the differentiated heating temperature control of andesite coarse aggregate and asphalt, do not adopt step-by-step mixing, and do not consider the asphalt coating state during the mixing process, which makes it difficult for andesite and asphalt to form a uniform coating, resulting in fluctuations in the performance of the mixture and thus poor preparation efficiency of andesite asphalt mixture.

[0007] To achieve the above objectives, in one aspect, the present invention provides a method for preparing andesite asphalt mixture, comprising: The heated andesite coarse aggregate, limestone manufactured sand and mineral filler are put into a mixer for dry mixing; heated asphalt and surface modifier are added for wet mixing at a preset mixing time and preset mixing speed. The andesite asphalt mixture is determined to be in a critical coating state based on the coating uniformity characterization value. The preset mixing speed of the mixer is increased according to the difference between the coating uniformity characterization value and the first preset coating uniformity characterization value in response to the critical coating state. After increasing the preset mixing speed of the mixer, when the profile sharpness characterization value of the andesite asphalt mixture is greater than or equal to the preset profile sharpness characterization value, the preset mixing speed is corrected. When the andesite asphalt mixture is determined to be in an uneven coating state based on the coating uniformity characterization value, the preparation adjustment strategy of the andesite asphalt mixture is determined based on the temperature drop rate of the andesite asphalt mixture. The preparation adjustment strategy is to spray a preset dose of atomized water into the mixer or to suspend wet mixing and trigger an asphalt replenishment alarm. Discharge the andesite asphalt mixture that meets the preset standards.

[0008] Further, the andesite coarse aggregate is heated to 180℃-190℃ to obtain heated andesite coarse aggregate; the limestone manufactured sand is heated to 170℃-185℃ to obtain heated limestone manufactured sand; and the asphalt is heated to 150℃-170℃ to obtain heated asphalt.

[0009] Furthermore, when the andesite asphalt mixture is determined to be in a critical coating state based on the comparison result that the coating uniformity characterization value is greater than or equal to the first preset coating uniformity characterization value and less than the second preset coating uniformity characterization value, the preset mixing speed of the mixer is increased according to the difference between the coating uniformity characterization value and the first preset coating uniformity characterization value, wherein the first preset coating uniformity characterization value is less than the second preset coating uniformity characterization value.

[0010] Furthermore, the process of obtaining the coating uniformity characterization value of the andesite asphalt mixture includes: The acquired surface image is converted to grayscale to obtain a grayscale image of the andesite asphalt mixture; Calculate the standard deviation of the grayscale values ​​of all pixels in the grayscale image; The standard deviation is used as the characterization value of the coating uniformity of the andesite asphalt mixture.

[0011] Furthermore, when the andesite asphalt mixture is determined to be in an uneven coating state based on the comparison result that the coating uniformity characterization value of the andesite asphalt mixture is greater than or equal to the second preset coating uniformity characterization value, the preparation adjustment strategy of the andesite asphalt mixture is determined based on the temperature drop rate of the andesite asphalt mixture.

[0012] Furthermore, after increasing the preset stirring rate, the process of determining whether the preparation of the andesite asphalt mixture meets the preset standard based on the contour sharpness characterization value of the andesite asphalt mixture includes: If the contour sharpness characterization value is less than the preset contour sharpness characterization value, then the preparation of the andesite asphalt mixture is determined to meet the preset standard; If the profile sharpness characterization value is greater than or equal to the preset profile sharpness characterization value, it is determined that the preparation of the andesite asphalt mixture does not meet the preset standard, and the preset mixing rate is corrected according to the difference between the profile sharpness characterization value and the preset profile sharpness characterization value. The sharpness characteristic value of the andesite asphalt mixture is determined by the interior angles of the outlines of several particles of the andesite asphalt mixture in the grayscale image.

[0013] Furthermore, several rate correction methods are provided for correcting the preset stirring rate, and each rate correction method has a different correction range for the preset stirring rate.

[0014] Furthermore, the process of determining the preparation adjustment strategy of the andesite asphalt mixture based on the temperature drop rate of the andesite asphalt mixture includes: If the temperature drop rate is less than the preset temperature drop rate, then a preset dose of atomized water is sprayed into the mixer. If the temperature drop rate is greater than or equal to the preset temperature drop rate, wet mixing is paused and an asphalt replenishment alarm is triggered.

[0015] Furthermore, the process of obtaining the temperature drop rate of the andesite asphalt mixture includes: The temperature of the andesite asphalt mixture at the start of wet mixing is recorded as the first temperature; The temperature of the andesite asphalt mixture after the preset wet mixing time is recorded as the second temperature. Calculate the difference between the first temperature and the second temperature, and record it as the temperature difference. The ratio of the temperature difference to the preset mixing time is denoted as the temperature drop rate of the andesite asphalt mixture.

[0016] On the other hand, the present invention provides an andesite asphalt mixture prepared by the above-described preparation method, wherein the andesite asphalt mixture is composed of the following components by mass percentage: 56%~77% andesite coarse aggregate, 11%~27% limestone manufactured sand, 2%~4% mineral filler, 4.5%~4.6% asphalt, and 0.4% surface modifier by mass of asphalt; each component is adjusted within the range to ensure that the total is 100%; wherein, the andesite coarse aggregate includes hot-filled crushed stone with particle sizes of 16-22mm, 11-16mm, 6-11mm, and 3-6mm, and the mass percentage of each particle size is 18%-30%, 16%-23%, 12%-20%, and 6%-8%; the limestone manufactured sand includes hot-filled crushed sand with a particle size of 0-3mm; the mineral filler is composed of mineral powder and cement in a mass ratio of 1:1.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: By introducing monitoring indicators such as coating uniformity characterization value, contour sharpness characterization value, and temperature drop rate, this invention constructs an intelligent closed loop of state recognition, precise control, and effect feedback. By acquiring images of the mixture surface in real time and quantitatively analyzing the coating state, it dynamically adjusts the stirring rate and stirring time, and adopts differentiated strategies such as atomized water spraying or asphalt replenishment, avoiding batch quality fluctuations and the generation of unqualified materials. At the same time, the differentiated heating temperature design and grading rate correction mechanism take into account both preparation efficiency and equipment safety, ensuring that the mixture achieves a high degree of uniformity in coating, structural density, and road performance. It fully utilizes the skeletal support potential of andesite, combined with the gap filling effect of limestone manufactured sand, the performance optimization effect of mineral fillers, and the adhesion strengthening function of surface modifiers, avoiding early defects such as water damage and loosening that are prone to occur in traditional mixtures, thereby improving the preparation efficiency of andesite asphalt mixtures.

[0018] Furthermore, this invention quantitatively evaluates the asphalt coating state by acquiring images of the mixture surface and calculating coating uniformity characterization values. It automatically and accurately identifies critical coating and uneven coating conditions, triggering corresponding dynamic adjustments, thus forming an intelligent judgment system that senses, judges, and executes. This not only ensures consistent coating uniformity for each batch of products but also reduces quality fluctuations caused by human factors.

[0019] Furthermore, this invention quantifies the determination of uneven coating and uses the temperature drop rate as the basis for adjustment strategies, thereby achieving state determination, cause analysis, and strategy matching. The temperature drop rate is directly related to the heat loss of the mixture and the fluidity of the asphalt, thus improving the level of intelligence in the determination.

[0020] Furthermore, the present invention sets a contour sharpness characterization value based on the inner angle of the particle contour in the grayscale image, which reflects the degree of wrapping of the edges and corners of the andesite aggregate, and has strong adaptability to the sharp edges and corners of andesite; at the same time, the stirring rate is corrected according to the contour sharpness characterization value to avoid mis-control, thereby improving the accuracy of process adjustment.

[0021] Furthermore, this invention utilizes andesite coarse aggregates of 56%-77% in four different particle size ranges to form a robust and tightly interlocked skeleton structure; 11%-27% limestone manufactured sand effectively fills the gaps between the coarse aggregates; 2%-4% mineral fillers further optimize the voids and asphalt film thickness; and 4.5%-4.6% asphalt content and 0.4% surface modifier by mass ensure sufficient bonding and coating while guaranteeing that the final product not only successfully utilizes inexpensive tunnel slag andesite, significantly reducing raw material costs, but also meets the stringent requirements of high-grade highways in terms of road performance, thereby ensuring the product quality stability of the andesite asphalt mixture. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation method of andesite asphalt mixture according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating how the coating state of the andesite asphalt mixture is determined based on the coating uniformity characterization value of the andesite asphalt mixture according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating how the preparation of andesite asphalt mixtures meets preset standards based on the contour sharpness characterization value of the andesite asphalt mixture in an embodiment of the present invention. Figure 4 This is a flowchart illustrating the process of determining the preparation adjustment strategy of the andesite asphalt mixture based on the temperature drop rate of the andesite asphalt mixture according to an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0024] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0025] It should be noted that the data in this embodiment are all derived from a comprehensive analysis and evaluation of historical test data and corresponding historical test results from the three months prior to this test. Those skilled in the art will understand that the method described in this invention can determine the above-mentioned parameters in the following ways: selecting the value with the highest proportion based on the data distribution as the preset standard parameter; using weighted summation to obtain the value as the preset standard parameter; substituting each historical data point into a specific formula and using the value obtained by that formula as the preset standard parameter; or other selection methods, as long as the method described in this invention can clearly define different specific situations in the single-item judgment process through the obtained values.

[0026] Please see Figure 1 , Figure 2 , Figure 3 as well as Figure 4 The following are flowcharts respectively: a flowchart of the preparation method of andesite asphalt mixture according to an embodiment of the present invention; a flowchart of determining the coating state of andesite asphalt mixture based on the coating uniformity characterization value of the andesite asphalt mixture according to an embodiment of the present invention; a flowchart of determining whether the preparation of andesite asphalt mixture meets the preset standard based on the contour sharpness characterization value of the andesite asphalt mixture according to an embodiment of the present invention; and a flowchart of determining the preparation adjustment strategy of andesite asphalt mixture based on the temperature drop rate of the andesite asphalt mixture according to an embodiment of the present invention.

[0027] The method for preparing andesite asphalt mixture according to embodiments of the present invention includes: Step S1: The heated andesite coarse aggregate, limestone manufactured sand and mineral filler are put into the mixer and dry-mixed at 60 r / min for 30 s; the heated asphalt and surface modifier are added and wet-mixed at a preset mixing time of 40 s and a preset mixing speed of 45 r / min. Step S2: During the wet mixing process, an industrial camera (resolution 1920×1080, lens protection level IP67, capable of withstanding high temperature environment) located outside the observation window of the mixer acquires surface images of the andesite asphalt mixture at a frequency of 2 frames per second, and obtains the uniformity characterization value of the coating of the andesite asphalt mixture. Step S3: Based on the coating uniformity characterization value, determine that the andesite asphalt mixture is in a critical coating state, and increase the preset mixing speed of the mixer in response to the critical coating state by increasing the preset mixing speed of the mixer based on the difference between the coating uniformity characterization value and the first preset coating uniformity characterization value. Step S4: After increasing the preset mixing speed of the mixer, when the profile sharpness characterization value of the andesite asphalt mixture is greater than or equal to the preset profile sharpness characterization value, the preset mixing speed is corrected. Step S5: When the andesite asphalt mixture is in an uneven coating state according to the coating uniformity characterization value, the preparation adjustment strategy of the andesite asphalt mixture is determined according to the temperature drop rate of the andesite asphalt mixture. The preparation adjustment strategy is to increase the preset mixing time or suspend wet mixing and trigger an asphalt replenishment alarm. Step S6: Discharge the andesite asphalt mixture that meets the preset standards.

[0028] In this embodiment, the andesite coarse aggregate is derived from the tunnel slag processed at the entrance of the Hulutouzi Tunnel of the project. After being crushed and screened by a jaw crusher, it is graded with particle sizes of 16-22mm, 11-16mm, 6-11mm, and 3-6mm, respectively.

[0029] In this embodiment, the limestone manufactured sand is limestone manufactured sand with a particle size of 0-3mm produced by Tieling Zhongxing Mining Group Dadi Mining Co., Ltd.

[0030] In this embodiment, the mineral filler is a mixture of mineral powder produced by Benxi Yongxing New Building Materials Co., Ltd. and P.042.5 cement produced by Liaoning Shanshui Gongyuan Cement Co., Ltd. in a mass ratio of 1:1.

[0031] In this embodiment, the asphalt used is 90# Grade A asphalt produced by Liaoning Petrochemical Branch of China National Petroleum Corporation, with a relative density (25℃) of 1.009-1.012 g / cm³. 3 The penetration (25℃, 5s, 100g) is 52-59 (0.1mm), the softening point is 71.5-76.5℃, the ductility at 5℃ is 41-46cm, the flash point is ≥243℃, the residual penetration ratio after TFOT is 65.4%-65.8%, the residual ductility is 27-28cm, the bonding performance is excellent, and it is resistant to high temperature aging.

[0032] In this embodiment, the surface modifier is an anti-stripping surface modifier produced by Shandong Silicon Science New Materials Co., Ltd., and the addition amount is 0.4% of the asphalt mass. It can improve the adhesion between the weakly acidic surface of andesite and asphalt, and avoid spalling caused by water damage. The surface modifier can be any kind of additive commonly used in the art to improve the adhesion between asphalt and aggregates, such as including but not limited to amines, alkanolamines and other anti-stripping agents.

[0033] Specifically, the andesite coarse aggregate is heated to 180℃-190℃ to obtain heated andesite coarse aggregate; the limestone manufactured sand is heated to 170℃-185℃ to obtain heated limestone manufactured sand; and the asphalt is heated to 150℃-170℃ to obtain heated asphalt.

[0034] In this embodiment, andesite coarse aggregate is heated to 185°C in a heating chamber, limestone manufactured sand is heated to 180°C, asphalt is heated to 160°C, and mineral filler is kept at room temperature (moisture content ≤0.5%).

[0035] Specifically, the coating state of the andesite asphalt mixture is determined based on the coating uniformity characterization value of the andesite asphalt mixture. If the coating uniformity characterization value is less than the first preset coating uniformity characterization value of 15, the andesite asphalt mixture is determined to be in a uniform coating state. If the coating uniformity characterization value is greater than or equal to the first preset coating uniformity characterization value and less than the second preset coating uniformity characterization value 30, then the andesite asphalt mixture is determined to be in a critical coating state, and the preset mixing speed of the mixer is increased according to the difference between the coating uniformity characterization value and the first preset coating uniformity characterization value. If the coating uniformity characterization value is greater than or equal to the second preset coating uniformity characterization value, the andesite asphalt mixture is determined to be in a state of uneven coating, and the preparation adjustment strategy of the andesite asphalt mixture is determined according to the temperature drop rate of the andesite asphalt mixture. Among them, the first preset uniform coating characterization value is less than the second preset uniform coating characterization value.

[0036] Specifically, the increase in the preset stirring rate is positively correlated with the coating uniformity deviation value. The positive correlation can be linear or nonlinear. The slope of the linear positive correlation is not specifically limited. It can be understood that the larger the coating uniformity deviation value, the greater the increase in the preset stirring rate. The coating uniformity deviation value is the difference between the coating uniformity value and the first preset coating uniformity value.

[0037] In this embodiment of the invention, the first preset uniform coating characterization value ranges from [10, 20], and the second preset uniform coating characterization value ranges from [25, 35]. Preferably, the first preset uniform coating characterization value is 15, and the second preset uniform coating characterization value is 30.

[0038] Specifically, the smaller the uniformity of coating value, the more uniform the surface grayness, meaning the more continuous and complete the distribution of the asphalt film; the larger the uniformity of coating value, the stronger the contrast between light and dark on the surface, the more uneven the asphalt distribution, and the more exposed aggregate points.

[0039] Specifically, when the uniform coating value is less than the first preset uniform coating value, it indicates that the asphalt film on the aggregate surface is continuous and intact with no obvious exposure, and the uniform coating is good. When the uniform coating value is greater than or equal to the first preset uniform coating value but less than the second preset uniform coating value, it indicates that there is slight to moderate uneven coating on the aggregate surface, with local aggregate exposure, but the internal asphalt penetration and mixing effect cannot be determined solely by the surface condition, and there is a potential risk of substandard performance. When the uniform coating value is greater than or equal to the second preset uniform coating value, it indicates severe defects in the asphalt coating on the aggregate surface, with a large amount of aggregate not being coated by asphalt or the asphalt film being broken, and the bonding performance and water stability of the mixture can hardly meet the design requirements.

[0040] Specifically, the process of obtaining the uniformity characterization value of the andesite asphalt mixture includes: The acquired color images were transmitted to an industrial computer equipped with OpenCV software. The images were then converted into 8-bit grayscale images using a weighted average method (using the formula: grayscale = 0.299 × R + 0.587 × G + 0.114 × B, where R represents the brightness value of the red channel; G represents the brightness value of the green channel; and B represents the brightness value of the blue channel). The grayscale values ​​ranged from 0 to 255, thus obtaining the grayscale image of the andesite asphalt mixture. The standard deviation of the grayscale values ​​of all pixels in the grayscale image is calculated by traversing all pixels in the grayscale image using OpenCV software. The standard deviation is used as the characterization value of the coating uniformity of the andesite asphalt mixture.

[0041] Specifically, the process of determining whether the preparation of the andesite asphalt mixture meets the preset standard based on the contour sharpness characterization value of the andesite asphalt mixture after increasing the preset stirring rate includes: If the contour sharpness characterization value is less than 6 preset contour sharpness characterization values, then the preparation of the andesite asphalt mixture is determined to meet the preset standard; If the profile sharpness characterization value is greater than or equal to the preset profile sharpness characterization value, it is determined that the preparation of the andesite asphalt mixture does not meet the preset standard, and the preset mixing rate is corrected according to the difference between the profile sharpness characterization value and the preset profile sharpness characterization value.

[0042] Specifically, when increasing the mixing rate is decided upon due to uneven coating, the aim is to enhance shear force to promote the coating of asphalt onto the edges of andesite asphalt particles. However, the improvement in coating morphology after speed increase needs to be verified through image analysis. The profile sharpness characterization value reflects the sharpness of the surface profile of andesite asphalt particles: if the profile sharpness characterization value is below a preset threshold after speed increase, it indicates that the speed increase strategy is effective, the asphalt is effectively coating the edges, and the mixture is developing towards a uniform state; if the profile sharpness characterization value is greater than or equal to the preset threshold, it indicates that the current speed increase operation has failed to effectively improve the coating morphology, possibly due to insufficient asphalt quantity, improper temperature, or aggregate surface characteristics. In this case, maintaining high-speed mixing will not only fail to improve quality but may also lead to asphalt aging or abnormal equipment wear due to ineffective shearing. Therefore, the mixing rate must be adjusted promptly according to the degree to which the profile sharpness characterization value exceeds the limit to ensure the applicability of process control.

[0043] Specifically, the preset contour sharpness characterization value can be in the range of [3, 10], with the interval unit being a number. Preferably, the preset contour sharpness characterization value is 6.

[0044] Specifically, the process of obtaining the profile sharpness characterization value of the andesite asphalt mixture includes: The grayscale image of the andesite asphalt mixture is binarized. A grayscale threshold is used to distinguish the particles of the andesite asphalt mixture from the background (asphalt and voids) to obtain a binary image. The grayscale threshold is determined by the Otsu binarization algorithm based on the overall grayscale distribution of the image. In this embodiment, the grayscale threshold is set to 120. The findContours function in OpenCV software is used to extract the contour data of all particles from the binary image. The contour of each andesite asphalt mixture particle is composed of a sequence of pixel coordinates, and tiny contours with an area of ​​less than 50 pixels are removed. The pixel coordinate sequence of the contour is resampled using spline interpolation to make the contour points evenly distributed; An outline polygon approximation algorithm (such as the Douglas-Peucker algorithm) is used to simplify the outline pixel sequence into a polygon composed of key vertices, where the key vertices are the corners or inflection points of the outline. The number of interior angles in each contour that are less than a preset angle threshold of 130 degrees is counted and recorded as the contour sharpness value. The arithmetic mean of the contour sharpness values ​​of all contours in the binary image is recorded as the contour sharpness characterization value of the andesite asphalt mixture.

[0045] Specifically, the profile sharpness characterization value is used to evaluate the smoothness of the profile of the particles of andesite asphalt mixture after they are wrapped in asphalt: the higher the profile sharpness characterization value, the sharper the overall profile and the less the edges are wrapped; the lower the profile sharpness characterization value, the smoother the overall profile and the better the asphalt coating.

[0046] Specifically, several rate correction methods are set for the correction of the preset stirring rate. If the deviation value of the outline sharpness is less than 3 of the first preset outline sharpness deviation value, then the preset stirring rate is corrected to the corresponding value using the first adjustment coefficient of 0.97. If the deviation value of the outline sharpness characterization is greater than or equal to the first preset outline sharpness characterization deviation value and less than the second preset outline sharpness characterization deviation value by 5, then the preset stirring rate is corrected to the corresponding value using the second adjustment coefficient of 0.94. If the deviation value of the outline sharpness characterization is greater than or equal to the second preset outline sharpness characterization deviation value, then the preset stirring rate is corrected to the corresponding value using the third adjustment coefficient of 0.91. The contour sharpness deviation value is the difference between the contour sharpness value and the preset contour sharpness value.

[0047] Specifically, the process of determining the preparation adjustment strategy of the andesite asphalt mixture based on the temperature drop rate of the andesite asphalt mixture includes: If the temperature drop rate is less than the preset temperature drop rate of 0.3℃ / s, then a preset dose of atomized water is sprayed into the mixer. If the temperature drop rate is greater than or equal to the preset temperature drop rate, wet mixing is paused and an asphalt replenishment alarm is triggered.

[0048] Specifically, the preset dosage of the atomized water is 0.1%-0.15% of the total mass of the andesite asphalt mixture. In this embodiment, the preset dosage is 0.1% of the total mass of the andesite asphalt mixture. At the same time, the atomized particle size of the atomized water is ≤50μm. When it is determined that the andesite asphalt mixture is in an uneven coating state and the real-time temperature drop rate is less than the preset temperature drop rate, the high-temperature resistant atomizing nozzle set on the upper part of the mixer shell starts spraying water for 3 seconds. Water vapor is briefly formed in the gaps between the particles of the andesite asphalt mixture, which can instantly reduce the frictional resistance between the particles, improve the overall workability of the mixture, and enable the slightly viscous asphalt to regain its ability to flow and distribute under shear force.

[0049] In this embodiment, if the temperature drop rate is greater than or equal to the preset temperature drop rate, wet mixing is paused, and an asphalt replenishment alarm is sent to the touch panel of the mixing machine control system. The alarm is triggered by an audible and visual prompt (a flashing red light and a buzzer sound), and a pop-up window on the panel displays: preheated asphalt needs to be added, and the recommended amount is 8%-12% of the original total asphalt volume, with an asphalt preheating temperature of 150℃-170℃. After the operator completes the asphalt replenishment according to the alarm prompt, the wet mixing program is restarted and the mixing time is extended by 30 seconds.

[0050] Specifically, the process of obtaining the temperature drop rate of andesite asphalt mixture includes: The temperature of the andesite asphalt mixture at the start of wet mixing is obtained by installing a high-temperature resistant K-type armored thermocouple on the inner side wall of the mixer, and is recorded as the first temperature; The temperature of the andesite asphalt mixture after the preset wet mixing time is recorded as the second temperature. Calculate the difference between the first temperature and the second temperature, and record it as the temperature difference. The ratio of the temperature difference to the preset mixing time is denoted as the temperature drop rate of the andesite asphalt mixture.

[0051] On the other hand, the andesite asphalt mixture prepared by the above preparation method in the embodiments of the present invention is composed of the following components by mass percentage: 56%-77% andesite coarse aggregate, 11%-27% limestone manufactured sand, 2%-4% mineral filler, 4.5%-4.6% asphalt, and 0.4% surface modifier by mass of asphalt; wherein, the andesite coarse aggregate includes hot-filled crushed stone with particle sizes of 16-22mm, 11-16mm, 6-11mm, and 3-6mm, and the mass percentage of each particle size is 18%-30%, 16%-23%, 12%-20%, and 6%-8%; the limestone manufactured sand includes hot-filled manufactured sand with a particle size of 0-3mm; the mineral filler is composed of mineral powder and cement in a mass ratio of 1:1.

[0052] Comparative experimental group 1: Example 1: The main raw materials were andesite coarse aggregate with particle sizes of 16-22mm, 11-16mm, 6-11mm, and 3-6mm, obtained from the self-processed tunnel slag at the entrance of the Hulutouzi Tunnel of the Benhuan Expressway Project, crushed and screened by a jaw crusher; limestone manufactured sand with a particle size of 0-3mm produced by Tieling Zhongxing Mining Group Dadi Mining Co., Ltd.; and mineral filler made by compounding mineral powder produced by Benxi Yongxing New Building Materials Co., Ltd. and P.042.5 cement produced by Liaoning Shanshui Gongyuan Cement Co., Ltd. in a mass ratio of 1:1. The main raw materials were 90# A grade asphalt produced by Liaoning Petrochemical Branch of China National Petroleum Corporation and anti-stripping surface modifier produced by Shandong Siker New Materials Co., Ltd. at an addition amount of 0.4% of the asphalt mass. The composition of the andesite asphalt mixture by mass percentage is as follows: 65.79% andesite coarse aggregate (each particle size range is proportioned according to the LAC-20 intermediate surface layer production mix ratio), 25.93% limestone manufactured sand, 3.84% mineral filler, 4.42% asphalt, and 0.018% surface modifier (0.4% of asphalt mass). In this embodiment, the total mass of the mixture is 100 kg.

[0053] In the preparation process, the andesite coarse aggregate was first heated to 185℃, the limestone manufactured sand to 180℃, and the asphalt to 160℃, while the mineral filler was kept at room temperature (moisture content ≤0.5%). Next, the heated andesite coarse aggregate, limestone manufactured sand, and mineral filler were added to a mixer and dry-mixed at 60 r / min for 30 seconds. Then, the heated asphalt and surface modifier were added, and wet-mixed at a preset mixing rate of 45 r / min. During the wet-mixing process, an industrial camera positioned outside the mixer's observation window captured images of the mixture surface at a frequency of 2 frames per second. After image processing, the uniform coating value was calculated to be 12, which was less than the first preset uniform coating value of 15. This indicated that the asphalt coating uniformity was good, and no process adjustment was triggered, resulting in the obtained andesite asphalt mixture.

[0054] Comparative Example 1: This comparative example uses the exact same raw materials and proportions as Example 1, but without any performance monitoring or adjustment measures, and is mixed according to fixed process parameters. Heated andesite coarse aggregate, limestone manufactured sand, and mineral filler are added to a mixer and dry-mixed at 60 r / min for 30 s; then heated asphalt and surface modifier are added, and wet-mixed at 45 r / min for 40 s; throughout the entire mixing process, no online monitoring or feedback control of images, current, or temperature is performed.

[0055] Comparative Example 2: The same process and intelligent control method as in Example 1 were used, but all aggregates were limestone and andesite was not used.

[0056] Table 1. Comparison of the properties of asphalt mixtures obtained by different preparation methods

[0057] As can be seen from the comparison in Table 1, the andesite asphalt mixture prepared using the intelligent control method of the present invention in Example 1 outperforms the traditional fixing process (Comparative Example 1) using the same materials in terms of Marshall stability, high-temperature rutting resistance (dynamic stability), and water stability (water-immersed Marshall residual stability). Furthermore, the performance of the andesite asphalt mixture prepared using the intelligent control method of the present invention in Example 1 reaches a level comparable to or even better than that of the mixture using only limestone (Comparative Example 2), demonstrating the effectiveness and superiority of the method of the present invention in preparing high-performance asphalt mixtures using low-adhesion andesite.

[0058] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing andesite asphalt mixture, characterized in that, include: The heated andesite coarse aggregate, limestone manufactured sand and mineral filler are put into a mixer and dry mixed. Add heated asphalt and surface modifier to perform wet mixing at a preset mixing time and preset mixing speed; During the wet mixing process, surface images of the andesite asphalt mixture are acquired, and the uniformity of coating of the andesite asphalt mixture is determined. The andesite asphalt mixture is determined to be in a critical coating state based on the coating uniformity characterization value. The preset mixing speed of the mixer is increased according to the difference between the coating uniformity characterization value and the first preset coating uniformity characterization value in response to the critical coating state. After increasing the preset mixing speed of the mixer, when the profile sharpness characterization value of the andesite asphalt mixture is greater than or equal to the preset profile sharpness characterization value, the preset mixing speed is corrected. When the andesite asphalt mixture is determined to be in an uneven coating state based on the coating uniformity characterization value, the preparation adjustment strategy of the andesite asphalt mixture is determined based on the temperature drop rate of the andesite asphalt mixture. The preparation adjustment strategy is to spray a preset dose of atomized water into the mixer or to suspend wet mixing and trigger an asphalt replenishment alarm. Discharge the andesite asphalt mixture that meets the preset standards.

2. The method for preparing andesite asphalt mixture according to claim 1, characterized in that, The andesite coarse aggregate is heated to 180℃-190℃ to obtain heated andesite coarse aggregate; the limestone manufactured sand is heated to 170℃-185℃ to obtain heated limestone manufactured sand; the asphalt is heated to 150℃-170℃ to obtain heated asphalt.

3. The method for preparing andesite asphalt mixture according to claim 1, characterized in that, When the andesite asphalt mixture is determined to be in a critical coating state based on the comparison result that the coating uniformity characterization value is greater than or equal to the first preset coating uniformity characterization value and less than the second preset coating uniformity characterization value, the preset mixing speed of the mixer is increased according to the difference between the coating uniformity characterization value and the first preset coating uniformity characterization value, wherein the first preset coating uniformity characterization value is less than the second preset coating uniformity characterization value.

4. The method for preparing andesite asphalt mixture according to claim 3, characterized in that, The process of obtaining the uniformity characterization value of the andesite asphalt mixture includes: The acquired surface image is converted to grayscale to obtain a grayscale image of the andesite asphalt mixture; Calculate the standard deviation of the grayscale values ​​of all pixels in the grayscale image; The standard deviation is used as the characterization value of the coating uniformity of the andesite asphalt mixture.

5. The method for preparing andesite asphalt mixture according to claim 4, characterized in that, When the andesite asphalt mixture is determined to be in an uneven coating state based on the comparison result that the coating uniformity characterization value of the andesite asphalt mixture is greater than or equal to the second preset coating uniformity characterization value, the preparation adjustment strategy of the andesite asphalt mixture is determined based on the temperature drop rate of the andesite asphalt mixture.

6. The method for preparing andesite asphalt mixture according to claim 4, characterized in that, The process of determining whether the preparation of the andesite asphalt mixture meets the preset standard based on the contour sharpness characterization value of the andesite asphalt mixture after increasing the preset stirring rate includes: If the contour sharpness characterization value is less than the preset contour sharpness characterization value, then the preparation of the andesite asphalt mixture is determined to meet the preset standard; If the profile sharpness characterization value is greater than or equal to the preset profile sharpness characterization value, it is determined that the preparation of the andesite asphalt mixture does not meet the preset standard, and the preset mixing rate is corrected according to the difference between the profile sharpness characterization value and the preset profile sharpness characterization value. The sharpness characteristic value of the andesite asphalt mixture is determined by the interior angles of the outlines of several particles of the andesite asphalt mixture in the grayscale image.

7. The method for preparing andesite asphalt mixture according to claim 6, characterized in that, Several rate correction methods are provided for correcting the preset stirring rate, and each rate correction method has a different correction range for the preset stirring rate.

8. The method for preparing andesite asphalt mixture according to claim 5, characterized in that, The process of determining the preparation adjustment strategy of the andesite asphalt mixture based on the temperature drop rate of the andesite asphalt mixture includes: If the temperature drop rate is less than the preset temperature drop rate, then a preset dose of atomized water is sprayed into the mixer. If the temperature drop rate is greater than or equal to the preset temperature drop rate, wet mixing is paused and an asphalt replenishment alarm is triggered.

9. The method for preparing andesite asphalt mixture according to claim 8, characterized in that, The process of obtaining the temperature drop rate of andesite asphalt mixture includes: The temperature of the andesite asphalt mixture at the start of wet mixing is recorded as the first temperature; The temperature of the andesite asphalt mixture after the preset wet mixing time is recorded as the second temperature. Calculate the difference between the first temperature and the second temperature, and record it as the temperature difference. The ratio of the temperature difference to the preset mixing time is denoted as the temperature drop rate of the andesite asphalt mixture.

10. The andesite asphalt mixture prepared by the preparation method according to any one of claims 1-9, characterized in that, The andesite asphalt mixture is composed of the following components by mass percentage: 56%~77% andesite coarse aggregate, 11%~27% limestone manufactured sand, 2%~4% mineral filler, 4.5%~4.6% asphalt, and 0.4% surface modifier by mass of asphalt; each component is adjusted within the range to ensure that the total is 100%; wherein, the andesite coarse aggregate includes hot-filled crushed stone with particle sizes of 16-22mm, 11-16mm, 6-11mm, and 3-6mm, with each particle size accounting for 18%-30%, 16%-23%, 12%-20%, and 6%-8% by mass; the limestone manufactured sand includes hot-filled manufactured sand with a particle size of 0-3mm; the mineral filler is composed of mineral powder and cement in a mass ratio of 1:1.

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