Fly ash quality rapid detection method based on net paste fluidity

Abstract

The present application relates to the technical field of material quality detection, and in particular to a fly ash quality rapid detection method based on net paste fluidity, which comprises: gradient temperature and humidity pretreatment of fly ash samples combined with composite modifier regulation to eliminate the influence of storage environment difference and particle agglomeration; net paste is prepared by using a dynamic water-binder ratio adaptation mechanism, and the ratio is fine-tuned in combination with the fly ash fineness preliminary screening result; the initial fluidity and decay characteristics under horizontal and micro-inclined states are synchronously detected in a temperature-controlled sealed environment through a double-station fluidity determination device; a random forest fusion determination model is constructed based on the fluidity characteristics and particle morphology parameters, and the fly ash activity index, loss on ignition and other core indexes and quality grades are rapidly output. The present application has the advantages of short detection time, high accuracy, no need for large and precise equipment, adaptation to fly ash detection of different storage conditions and types, strong environmental adaptability, full detection dimension, and high-precision and efficient results.

Description

Technical Field

[0001] This invention relates to the field of material quality testing technology, specifically a rapid method for testing the quality of fly ash based on the fluidity of slurry. Background Technology

[0002] Fly ash, a major industrial byproduct of coal-fired power plants, has become a core component of concrete admixtures due to its pozzolanic activity and micro-aggregate filling effect, playing an irreplaceable role in reducing concrete hydration heat, improving durability, and conserving cement resources. With the deepening of green building concepts, the resource utilization rate of fly ash continues to improve. However, its quality stability is greatly affected by multiple factors such as production processes, storage environment, transportation conditions, and particle characteristics. If the quality is substandard, it will directly lead to a decline in concrete workability, insufficient mechanical strength, and even potential structural safety hazards. Therefore, establishing accurate and efficient fly ash quality testing methods suitable for actual application scenarios is crucial to ensuring project quality and the rational utilization of resources.

[0003] Currently, fly ash quality testing mainly relies on the GB / T 1596-2017 standard, with core indicators including activity index, loss on ignition, water requirement ratio, and fineness. However, existing testing methods and related improvement technologies still have many limitations. Firstly, sample processing has shortcomings: most methods only employ a single temperature and humidity balancing process, ignoring the different dry and wet storage environments fly ash may face on-site, leading to significant deviations between sample conditions and actual application conditions. Furthermore, the lack of targeted modification and control results in fly ash particles easily agglomerating and unstable surface humidity, interfering with the accuracy of subsequent testing. Secondly, the preparation ratio of the slurry is rigid, often using a fixed water-cement ratio, failing to consider the impact of fly ash fineness differences on water requirement, and the mixing process struggles to balance mixing uniformity and particle dispersion, resulting in insufficient representativeness of flowability data.

[0004] Furthermore, current flowability testing methods are limited to a single dimension, only measuring flowability in horizontal conditions. This fails to simulate the slight slopes encountered during on-site pouring, and the lack of humidity control and aeration in the testing environment leads to abnormal moisture evaporation and data distortion. Additionally, the quality assessment logic is incomplete, relying heavily on single flowability data and linear model correlations without integrating core physical parameters such as particle morphology. This makes it difficult to accurately capture nonlinear correlation patterns and differentiate between different grades of fly ash with similar quality. Existing improvement technologies primarily focus on optimizing single aspects, failing to achieve a synergistic breakthrough across the entire process. This results in a trade-off between testing efficiency, accuracy, and environmental adaptability, necessitating the development of a rapid testing method that optimizes the entire process and integrates multiple parameters. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing fly ash quality testing methods, such as long cycle, poor environmental adaptability, single testing dimensions, incomplete judgment parameters, and insufficient accuracy. By optimizing the entire process through gradient temperature and humidity pretreatment and composite modification, dynamic water-binder ratio adaptation, dual-station temperature and air permeability testing, and multi-feature fusion judgment, this invention provides a fast, accurate, and engineering-adaptable fly ash quality testing method that meets the needs of efficient on-site and laboratory management.

[0006] The technical solution adopted by this invention to solve its technical problem is: a rapid detection method for fly ash quality based on the fluidity of slurry, comprising the following steps: (1) Gradient pretreatment and modification control of fly ash samples: Take 500g of sample and pass it through a 0.08mm sieve. If the mass fraction of the residue on the sieve is ≤0.5%, it is retained; otherwise, it is taken again. Divide the sample into two equal parts and place them in an environment of 25±1℃ and 45±3%RH and 25±1℃ and 55±3%RH respectively for 1.5h to balance. After mixing, stir gently at a rate of ≤50r / min for 30s, and then place them in an environment of 25±1℃ and 50±2%RH for 0.5h to balance. Add a composite modifier to the balanced sample. The composite modifier is composed of polycarboxylic acid dispersant (molecular weight 2000-5000Da, solid content ≥40%) and food-grade trehalose in a mass ratio of 2:1. The amount added is 0.05-0.1% of the mass of the fly ash sample. After stirring evenly, let it stand for 10min. (2) Preparation of dynamically adapted neat cement paste: The negative pressure sieve method was used to determine the residue on the 45μm sieve. The detection time was ≤5min and the error of a single detection was ≤1%. If the residue on the 45μm sieve was ≤15%, the water-cement ratio was set to 0.44; if the residue was 15%-25%, the water-cement ratio was set to 0.46; if the residue was >25%, the water-cement ratio was set to 0.48. The pretreated modified fly ash and P·O42.5 cement were mixed at a mass ratio of 1:1 to form a cementitious material. Tap water that meets the JGJ 63-2006 standard (the temperature difference between the water and the ambient temperature is ≤2℃) was added. The mixture was stirred at a planetary mixer at a low speed of 280±20r / min for 2min, a medium speed of 450±20r / min for 2min (the pot wall was scraped once when the mixture reached 1min, and the scraping time was ≤10s), and a high speed of 620±20r / min for 1min to prepare a uniform neat cement paste. (3) Dual-station flowability test: A dual-station flowability measuring device is used. One side is a horizontal optical quartz glass plate (roughness Ra≤0.02μm), and the other side is an optical quartz glass plate with an inclination angle of 3° (inclination angle error≤0.2°). The test molds are all 60mm high and 50mm inner diameter. The paste is poured into the test mold, leveled and lifted. After 30s, the characteristic diameter of the diffusion circle (horizontal) or ellipse (inclination) of the two stations is measured, and the average value is taken as the initial flowability. The sealed cover with reserved air holes (air permeability rate 5-8mL / min) is placed in the environment of 25±1℃ and left to stand for 30min and 60min. The attenuation flowability is repeatedly tested. Each station is tested 3 times at each time period. The error of a single test is ≤2mm. The ambient temperature and humidity are recorded simultaneously. (4) Feature fusion quality judgment: The roundness and angularity parameters of fly ash particles are extracted by a high-definition industrial camera (pixel ≥ 5 million, shooting distance 10cm), and the recognition time is ≤ 2min; the flowability data, particle morphology parameters and environmental temperature and humidity data of each time period of the dual station are integrated and input into the fusion judgment model constructed based on the random forest algorithm; the model is calibrated by more than 500 sets of standard samples (covering grades I-III and unqualified products), and the fitting degree R is ≥ 100%. 2 ≥0.92, output the predicted values ​​of activity index, loss on ignition, and water requirement ratio, and determine the quality grade according to GB / T 1596-2017. When the critical value is reached, supplement the correction result of the 7-day compressive strength ratio of the paste.

[0007] Specifically, in step (1), the composite modifier can effectively disperse fly ash particles, lock in moisture on the sample surface, and maintain particle dispersibility and humidity stability.

[0008] Specifically, in step (3), the sealing cover can prevent changes in ambient humidity from affecting the evaporation of moisture in the paste, while simulating the actual air-permeable environment of the project.

[0009] Specifically, in step (4), the random forest model is calibrated with multiple sets of standard samples, which can accurately capture the nonlinear correlation between mobility, particle morphology and quality indicators.

[0010] Specifically, in step (2), the three-stage variable speed stirring combined with the scraping of the pot wall can ensure that the cementitious material is mixed evenly, the particles are fully dispersed, and there is no clumping.

[0011] Specifically, the method is applicable to dry-discharged, wet-discharged, and finely ground fly ash stored for 1-90 days, and no additional drying or wetting treatment is required before testing.

[0012] Specifically, in step (3), the average value of the two diameters of the diffusion circle that are perpendicular to each other is taken for the horizontal station, and the average value of the major axis and minor axis of the ellipse is taken for the inclined station as the final flowability data.

[0013] Specifically, gentle stirring in step (1) can prevent fly ash particles from breaking and ensure that the original properties of the sample are not damaged.

[0014] Specifically, in step (2), the tap water must meet the requirements of the concrete water standard (JGJ 63-2006) to avoid water quality interfering with the fluidity of the paste.

[0015] Specifically, in step (4), the particle morphology parameter extraction requires shooting three random locations of the sample to ensure the representativeness of the parameters.

[0016] The beneficial effects of this invention are: High sample processing adaptability: Gradient temperature and humidity pretreatment simulates the actual storage environment, and composite modifier regulates particle and humidity characteristics. The dual effect eliminates the differences in initial state and agglomeration interference, making the sample state closer to the actual engineering situation and adaptable to different storage conditions and types of fly ash.

[0017] The data representativeness of the paste is excellent: the dynamic water-cement ratio adapts to the fineness difference, and the three-stage mixing combined with the scraping of the pot wall ensures that the paste is evenly dispersed and avoids excessive or insufficient fluidity, providing a reliable data basis for subsequent testing.

[0018] Comprehensive and accurate detection dimensions: Dual-station simultaneous capture of flow characteristics in horizontal and inclined states, temperature control and ventilation of the sealing cover to simulate the construction environment, dynamic detection of initial and decay flow, and multi-dimensional data that better matches actual application scenarios.

[0019] The assessment is efficient, accurate, and low-cost: detection is completed within 90 minutes, without the need for a 28-day intensity waiting period; the random forest model integrates mobility and particle parameters, resulting in high fitting and accuracy, and it does not require large-scale precision equipment, making it easy to operate. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0021] The present invention discloses a rapid method for detecting fly ash quality based on the fluidity of slurry, comprising the following steps: S1. Gradient Pretreatment and Modification Control of Fly Ash Samples: Take 500g of fly ash sample and sieve it using a 0.08mm standard negative pressure sieve. Weigh the mass of the residue. If the mass fraction of the residue exceeds 0.5%, re-sampling is required to ensure sample representativeness. Divide the qualified sample into two equal portions (250g each) and place them in constant temperature and humidity chambers. Place the first portion in an environment of 25±1℃ and 45±3%RH for 1.5h (simulating dry storage), and the second portion in an environment of 25±1℃ and 55±3%RH for 1.5h (simulating humid storage). After equilibration, pour them into the same mixing bowl and gently stir at a rate of ≤50r / min for 30s (to avoid particle breakage). Then place them in an environment of 25±1℃ and 50±2%RH for 0.5h to eliminate differences in storage environment. Subsequently, a composite modifier is added. This modifier is a mixture of polycarboxylic acid dispersant (molecular weight 2000-5000 Da, solid content ≥40%) and food-grade trehalose at a mass ratio of 2:1. The amount added is 0.05-0.1% of the sample mass. After stirring evenly, the mixture is allowed to stand for 10 minutes. The dispersant breaks up agglomerates, and the trehalose locks in moisture, thus achieving dual regulation of particle dispersibility and humidity stability.

[0022] S2. Dynamically Adapted Cement Pulp Preparation: A 45μm standard negative pressure sieve is used for rapid sample fineness detection. The detection time is ≤5min, and the single-test error is ≤1%. The water-cement ratio is dynamically adjusted according to the fineness: 0.44 for 45μm sieve residue ≤15% (mainly fine particles), 0.46 for 15%-25% (balanced coarse and fine particles), and 0.48 for >25% (mainly coarse particles), adapting to the water requirements of different particle sizes. Pretreated and modified fly ash is mixed with P·O42.5 cement at a 1:1 ratio to obtain 400g of cementitious material, which is then poured into a planetary mixer. Tap water conforming to JGJ 63-2006 standard is added, controlling the water temperature difference with the ambient temperature to ≤2℃, and the water volume is added according to the set water-cement ratio. Start the mixer and use a three-stage variable speed mixing method: low speed 280±20r / min for 2min (initial mixing), medium speed 450±20r / min for 2min (scrape the pot wall once after 1min of mixing, ≤10s, to break up agglomerates), and high speed 620±20r / min for 1min (fully disperse), finally obtaining a uniform, fine, and lump-free paste.

[0023] S3. Dual-station flowability testing: A customized dual-station flowability measuring device is used. Both stations use optical quartz glass plates (roughness Ra≤0.02μm), one side is horizontal, and the other side is tilted at a 3° angle (error≤0.2°). The mold is a cylinder with a height of 60mm and an inner diameter of 50mm. The paste is divided into two portions and poured into the molds at the two stations respectively. After smoothing and removing air bubbles, the molds are lifted vertically at a rate of 5cm / s. The flowability is measured after 30s: for the horizontal station, the average of the two perpendicular diameters is taken; for the tilted station, the average of the major and minor axes of the ellipse is taken as the initial flowability. The glass plates at both stations are placed in a sealed cover (with pre-reserved vents, venting rate 5-8mL / min) and placed in an environment of 25±1℃ for static testing. The decay flowability is repeatedly tested after 30min and 60min. Each station is tested 3 times at each time point, with a single error ≤2mm. The ambient temperature and humidity are recorded simultaneously as auxiliary parameters.

[0024] S4. Feature Fusion Quality Assessment: Using a high-definition industrial camera with a resolution of 5 megapixels or higher, three random points on the pre-processed sample are photographed at a distance of 10cm. Particle roundness and angularity parameters are extracted using image recognition software, with an identification time ≤2min. Initial and 30min and 60min decay flowability data from the dual-station setup are integrated with particle morphology parameters and environmental temperature and humidity data, and input into a fusion assessment model based on a random forest algorithm. This model is calibrated using over 500 sets of standard samples covering grades I-III and substandard fly ash (standard indicators are accurately measured according to GB / T 1596-2017), with a goodness of fit R0. 2 A value ≥0.92 allows for rapid output of predicted values ​​for activity index, loss on ignition, and water requirement ratio. The quality grade is determined by comparing the predicted value with GB / T 1596-2017. If the predicted value is at the critical value, the 7-day compressive strength ratio of the paste is tested to correct the judgment result and improve accuracy.

[0025] Example 1: Quality testing of dry-stored fly ash. This example focuses on the testing of dry-stored fly ash samples stored in a dry environment (42-46%RH, 30 days). The steps are as follows: S1. Pretreatment and Modification: Take 500g of sample and pass it through a 0.08mm sieve. The residue on the sieve is 1.2g (0.24%), which is qualified. Divide into two portions of 250g each and equilibrate at 25℃ and 44%RH and 25℃ and 54%RH respectively for 1.5h. After gently stirring at 45r / min for 30s, equilibrate at 25℃ and 50%RH for 0.5h respectively. Add a composite modifier (3000Da polycarboxylate dispersant + trehalose = 2:1, solid content 45%) at an addition amount of 0.08%, stir and let stand for 10min. The sample is uniformly dispersed and the moisture content is stable.

[0026] S2. Preparation of Neat Cement Paste: 12.3% residue on a 45μm sieve, water-cement ratio 0.44. Mix 200g fly ash and 200g cement, then add 176g tap water (water temperature 24.8℃, temperature difference 0.2℃). Three-stage mixing: mix at 280r / min for 2min, mix at 450r / min for 2min (scraping for 8s at 1min), and mix at 620r / min for 1min. The resulting neat cement paste is fine and free of lumps.

[0027] S3. Dual-station testing: Horizontal glass plate Ra=0.016μm, inclined station inclination angle 3.0° (error 0.1°). Initial flowability: horizontal 229mm (228 / 230mm), inclined 227.5mm (245 / 210mm). Air permeability of the sealing cover 6mL / min, after standing at 25℃: 30min horizontal 215mm, inclined 213mm; 60min horizontal 202mm, inclined 200mm. Single-pass error ≤1.8mm, stable temperature and humidity.

[0028] S4. Quality Assessment: Parameters were extracted from images captured by an industrial camera: roundness 0.78, angle coefficient 0.22. Data was input into the model, predicting the following values: activity index 89%, loss on ignition 3.1%, water requirement ratio 94%. Comparing with GB / T 1596-2017, the grade was determined to be Class I. Standard method verification showed an actual value deviation of ≤0.4%, requiring no additional strength testing, and it can be used for high-performance concrete.

[0029] Example 2: Quality Testing of Wet-Discharged Fly Ash Stored in Humid Environments. This example focuses on the testing of wet-discharged fly ash samples stored in a humid environment (53-57%RH, 45 days). The steps are as follows: S1. Pretreatment and Modification: 500g of sample was passed through a 0.08mm sieve, with 1.8g (0.36%) of residue, which was acceptable. The sample was divided into two 250g portions and equilibrated at 26℃ and 46%RH and 26℃ and 56%RH for 1.5h respectively. After stirring at 48r / min for 30s, the samples were equilibrated at 26℃ and 51%RH for 0.5h. A composite modifier (4000Da polycarboxylate dispersant + trehalose = 2:1, solid content 42%) was added at a rate of 0.09%. After standing, the sample showed no localized moisture absorption or clumping.

[0030] S2. Preparation of Neat Cement Paste: 18.5% residue on a 45μm sieve, water-cement ratio 0.46. Mix 200g fly ash and 200g cement, then add 184g tap water (water temperature 25.9℃, temperature difference 0.1℃). Three-stage mixing: mix at 290r / min for 2min, mix at 460r / min for 2min (scraping for 9s at 1min), and mix at 630r / min for 1min until the neat cement paste has uniform fluidity.

[0031] S3. Dual-station testing: Horizontal glass plate Ra=0.017μm, inclined station angle 2.9° (error 0.1°). Initial flowability: horizontal 219mm (218 / 220mm), inclined 218.5mm (232 / 205mm). Air permeability of the sealing cover 7mL / min, after standing at 26℃: 30min horizontal 206mm, inclined 205mm; 60min horizontal 193mm, inclined 192mm. Single-pass error ≤1.6mm, humidity stable with no fluctuations.

[0032] S4. Quality Assessment: Extracted particle parameters: roundness 0.72, angularity coefficient 0.27. Model output predicted values: activity index 76%, loss on ignition 4.7%, water requirement ratio 97%. Compared with the standard, it is classified as Grade II. The water requirement ratio is close to the critical value. A supplementary 7-day compressive strength ratio of 77% confirms Grade II, suitable for ordinary concrete. The standard verification deviation is extremely small, and the results are reliable.

[0033] Example 3: Quality testing of finely ground fly ash after long-term storage. This example focuses on the testing of finely ground fly ash samples after long-term storage (80 days, 48-52%RH). The steps are as follows: S1. Pretreatment and Modification: 500g of sample was passed through a 0.08mm sieve, with a residue of 0.9g (0.18%), which was acceptable. The sample was divided into two 250g portions and equilibrated at 24℃ and 43%RH and 24℃ and 53%RH for 1.5h respectively, with gentle stirring at 42r / min for 30s (to protect fine particles), followed by equilibration at 24℃ and 49%RH for 0.5h. A composite modifier (2500Da polycarboxylate dispersant + trehalose = 2:1, solid content 48%) was added at a rate of 0.07%. After standing, the particles showed no agglomeration and the moisture content was uniform.

[0034] S2. Preparation of Neat Cement Paste: 8.6% residue on a 45μm sieve, water-cement ratio 0.44. Mix 200g fly ash and 200g cement, then add 176g tap water (water temperature 23.8℃, temperature difference 0.2℃). Three-stage mixing: mix at 270r / min for 2min, mix at 440r / min for 2min (scraping for 7s at 1min), and mix at 610r / min for 1min. The neat cement paste exhibits excellent fluidity and no particle accumulation.

[0035] S3. Dual-station testing: Horizontal glass plate Ra=0.015μm, inclined station angle 3.1° (error 0.1°). Initial flowability: horizontal 239mm (238 / 240mm), inclined 236.5mm (255 / 218mm). Air permeability rate of the sealing hood 5.5mL / min, after standing at 24℃: 30min horizontal 224mm, inclined 222mm; 60min horizontal 211mm, inclined 209mm. Single-pass error ≤1.2mm, flowability decay is gradual.

[0036] S4. Quality Assessment: Extracted particle parameters: roundness 0.83, angularity coefficient 0.18 (edges ground after fine grinding). Model output predicted values: activity index 93%, loss on ignition 2.4%, water requirement ratio 91%. The standard assessment classifies it as Grade I, with a supplementary 7-day compressive strength ratio of 83%, confirming excellent quality suitable for high-performance concrete. Standard verification deviation ≤0.2%, indicating extremely high agreement.

[0037] Compared to Example 1, the detection method without composite modifier: The sample from Example 1 was used, but only gradient pretreatment was performed without composite modifier; all other steps were the same. The detection showed an accelerated rate of flow decay in the dual-station process. The model predicted values: activity index 84%, loss on ignition 3.7%, and water demand ratio 97%, which deviated significantly from the standard values ​​(activity index deviation 4.6%), making accurate determination of Grade I impossible. This demonstrates that composite modifiers are crucial for maintaining particle dispersibility and stabilizing flow data.

[0038] Comparative Example 2, the fixed water-cement ratio test method: Using the sample from Example 2, a fixed water-cement ratio of 0.45 was used instead of dynamic adaptation, with all other steps remaining the same. The paste fluidity was insufficient. The model predicted values: activity index 71%, loss on ignition 5.3%, and water requirement ratio 101%, which deviated significantly from the standard values ​​and were determined to be critical values. This indicates that a fixed water-cement ratio cannot adapt to fineness characteristics, leading to data distortion; dynamic adaptation can improve representativeness.

[0039] Compared to Example 3, the single-station detection method: using the sample from Example 3, only the horizontal station was tested, with all other steps remaining the same. Modeling based solely on horizontal flow data resulted in a large deviation between the predicted and standard values, with a model fit of only 0.85. This demonstrates that dual-station detection can capture inclined flow characteristics, supplement key data, and improve judgment accuracy.

[0040] Compared to Example 4, the method for determining the absence of particle morphology parameters: using the sample from Example 1, modeling was performed only with dual-station flowability data, without particle parameters, and all other steps were the same. The model prediction accuracy decreased, deviating from the standard value by 3.6% (activity index). Although it could determine Level I, the accuracy was insufficient. This indicates that incorporating particle morphology parameters can enhance the capture of nonlinear correlations and improve the reliability of the model.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rapid method for detecting fly ash quality based on the fluidity of slurry, characterized in that, Includes the following steps: (1) Gradient pretreatment and modification control of fly ash samples: Take 500g of sample and pass it through a 0.08mm sieve. If the mass fraction of the residue on the sieve is ≤0.5%, it is retained; otherwise, it is taken again. Divide the sample into two equal parts and place them in an environment of 25±1℃ and 45±3%RH and 25±1℃ and 55±3%RH respectively for 1.5h to balance. After mixing, stir gently at a rate of ≤50r / min for 30s, and then place them in an environment of 25±1℃ and 50±2%RH for 0.5h to balance. Add a composite modifier to the balanced sample. The composite modifier is composed of polycarboxylic acid dispersant and food-grade trehalose in a mass ratio of 2:

1. The amount added is 0.05-0.1% of the mass of the fly ash sample. After stirring evenly, let it stand for 10min. (2) Dynamically adaptable paste preparation: The residue on the 45μm sieve was determined by the negative pressure sieve method. The detection time was ≤5min and the error of a single detection was ≤1%. If the residue on the 45μm sieve was ≤15%, the water-cement ratio was set to 0.

44. When the sieve residue is 15%-25%, the water-cement ratio is set to 0.46; when the sieve residue is >25%, the water-cement ratio is set to 0.

48. The pretreated modified fly ash and P·O42.5 cement are mixed at a mass ratio of 1:1 to form a cementitious material. Standard tap water is added, and the mixture is stirred at a planetary mixer at low speed (280±20 r / min) for 2 min, medium speed (450±20 r / min) for 2 min, and high speed (620±20 r / min) for 1 min to prepare a uniform paste. (3) Dual-station flowability test: A dual-station flowability measuring device is used. One side is a horizontal optical quartz glass plate with a roughness Ra≤0.02μm, and the other side is an optical quartz glass plate with an inclination angle of 3° and an inclination angle error ≤0.2°. The test molds are all 60mm high and 50mm inner diameter. The slurry is poured into the test mold, leveled and lifted. After 30s, the characteristic diameter of the diffusion circle or ellipse of the two stations is measured and the average value is taken as the initial flowability. The sealed cover with reserved air holes is placed in the mold with an air permeability rate of 5-8mL / min. After standing in an environment of 25±1℃ for 30min and 60min, the decay flowability is repeatedly tested. Each station is tested 3 times at each time period. The error of a single test is ≤2mm. The ambient temperature and humidity are recorded simultaneously. (4) Feature fusion quality judgment: The roundness and angularity parameters of fly ash particles are extracted by high-definition industrial camera, and the recognition time is ≤2min; The flowability data, particle morphology parameters, and ambient temperature and humidity data of the dual-station system at different time periods were integrated and input into a fusion judgment model constructed based on the random forest algorithm. The model was calibrated with more than 500 sets of standard samples covering grades I-III and non-conforming products, and the goodness of fit R was achieved. 2 ≥0.92, output the predicted values ​​of activity index, loss on ignition, and water requirement ratio, and determine the quality grade according to GB / T 1596-2017. When the critical value is reached, supplement the correction result of the 7-day compressive strength ratio of the paste.

2. The rapid fly ash quality detection method based on the fluidity of the slurry according to claim 1, characterized in that: In step (1), the composite modifier can effectively disperse fly ash particles, lock in moisture on the sample surface, and maintain particle dispersibility and humidity stability.

3. The rapid fly ash quality detection method based on the fluidity of the slurry according to claim 1, characterized in that: In step (3), the sealing cover can prevent changes in ambient humidity from affecting the evaporation of moisture in the paste, while simulating the actual air-permeable environment of the project.

4. The rapid fly ash quality detection method based on the fluidity of the slurry according to claim 1, characterized in that: In step (4), the random forest model is calibrated with multiple sets of standard samples, which can accurately capture the nonlinear correlation between mobility, particle morphology and quality indicators.

5. The rapid method for detecting fly ash quality based on the fluidity of slurry according to claim 1, characterized in that: In step (2), the three-stage variable speed stirring combined with the scraping of the pot wall can ensure that the cementitious material is mixed evenly, the particles are fully dispersed, and there is no clumping.

6. The rapid method for detecting fly ash quality based on the fluidity of slurry according to claim 1, characterized in that: The method is applicable to dry-discharged, wet-discharged, and finely ground fly ash stored for 1-90 days, and no additional drying or wetting treatment is required before testing.

7. The rapid method for detecting fly ash quality based on the fluidity of slurry according to claim 1, characterized in that: In step (3), the average value of the two diameters of the diffusion circle that are perpendicular to each other is taken for the horizontal station, and the average value of the major axis and minor axis of the ellipse is taken for the inclined station as the final flowability data.

8. The rapid method for detecting fly ash quality based on the fluidity of slurry according to claim 1, characterized in that: In step (1), gentle stirring can prevent fly ash particles from breaking and ensure that the original properties of the sample are not damaged.

9. The rapid method for detecting fly ash quality based on the fluidity of slurry according to claim 1, characterized in that: In step (2), the tap water must meet the requirements of the concrete water standard to avoid water quality interfering with the fluidity of the cement paste.

10. The rapid method for detecting fly ash quality based on the fluidity of slurry according to claim 1, characterized in that: In step (4), the particle morphology parameters need to be extracted by taking pictures of three random locations on the sample to ensure the representativeness of the parameters.