Design method for realizing concrete fluidity optimization through viscosity regulation and control

Abstract

The invention relates to the technical field of concrete fluidity regulation and control, in particular to a design method for realizing concrete fluidity optimization through viscosity regulation and control, which comprises the following steps: S1, determining the proportion range of each component of the required concrete according to the strength grade; s2, inputting the environment and process parameters into a pre-constructed required viscosity prediction model to obtain the required viscosity of the concrete corresponding to the environment and process parameters; s3, inputting the proportion of the cement, the coarse aggregate, the fine aggregate, the fly ash, the mineral powder, the silica fume, the water and the water reducing agent into a pre-constructed concrete viscosity prediction model to obtain concrete predicted viscosity; s4, comparing the required viscosity with the concrete predicted viscosity; the viscosity of the concrete in different proportions and the required viscosity under the condition that the environment and process parameters are determined can be predicted, and the common problems of overhigh pump pressure, pumping difficulty and pump blockage in elevation concrete pumping engineering are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete fluidity regulation, and in particular to a design method for optimizing concrete fluidity through viscosity regulation. Background Art

[0002] The superstructure of continuous rigid frame bridges in highway projects generally uses C55 concrete, and the bridge height is generally high, so long-distance pumping technology must be used in concrete pouring construction. This requires us to avoid poor performance of pumped concrete, severe segregation, water seepage and sand overflow caused by unreasonable mix design or changes in machine-made sand when designing the C55 concrete mix ratio. At the same time, the concrete should have a certain fluidity to prevent the concrete from getting stuck in the pipe during the pumping process, which affects the quality of concrete pouring and long-term durability.

[0003] At present, there is a lack of systematic design methods for high-altitude pumping concrete projects. The main reason is that the high viscosity of concrete leads to excessive pump pressure, difficulty in pumping, and easy pump blockage during pumping construction, affecting safety and construction period; the contradiction between the high fluidity of concrete and the homogeneous stability and workability of the mixture. When the concrete mixture is in a state of high fluidity, the slurry is prone to float up and the aggregate sinks, resulting in stratification and segregation, which is not conducive to pumping construction;

[0004] Different heights have different requirements for concrete fluidity and stability. Changes in pumping height will also affect the working performance of concrete. It is necessary to study the specific impact of height changes on concrete performance, design appropriate concrete mix ratios for different height intervals, and adjust the construction plan. How to optimize concrete fluidity and achieve a balance between concrete fluidity and stability based on different heights is an urgent problem to be solved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a design method for optimizing concrete fluidity through viscosity control, which can predict the viscosity of concrete under different mix ratios and the required viscosity under certain environmental and process parameters, and effectively solve the common problems of excessive pumping pressure, pumping difficulties and pump blockage in elevation pumping concrete projects. This not only improves construction efficiency and safety, but also ensures construction quality, adapts to pumping requirements at different heights, and provides strong technical support for achieving efficient, safe and high-quality construction.

[0006] A design method for optimizing concrete fluidity by viscosity control of the present invention comprises the following steps:

[0007] S1. Determine the required strength grade of concrete according to industry standards, and determine the proportion range of each component of the required concrete according to the strength grade, the components include cement, coarse aggregate, fine aggregate, fly ash, mineral powder, silica fume, water and water reducing agent;

[0008] Industry standards can adopt GB / T 50164 "Concrete Quality Control Standard" or ASTM C94 "Standard Specification for Concrete" to determine the concrete strength grade required for the project;

[0009] The present invention is aimed at the bridge design of Guizhou Huajiang Gorge Bridge. The project requires the delivery of C55 strength concrete with a pumping height range of 0 to 260m. In order to meet the needs of the bridge, high-strength concrete can provide sufficient bearing capacity and can withstand greater loads and stresses, including its own weight, traffic loads, and the influence of natural factors such as wind. At the same time, concrete with a strength grade of C55 has better density and lower permeability, which means that it has stronger resistance to environmental factors and ensures the safety of the bridge.

[0010] Different pumping heights have different requirements for the fluidity and stability of concrete. Changes in pumping height will also affect the working performance of concrete. By determining the required proportion range of each component of concrete in advance, it can be ensured that when adjusted within these ranges, the strength of the concrete still meets the predetermined indicators. For example, by adjusting the proportion of cement, coarse aggregate, fine aggregate, etc., the fluidity of concrete can be optimized while ensuring strength.

[0011] As a preferred embodiment of the present invention, the cement used is low hydration heat, low alkali content silicate cement or ordinary silicate cement produced by a large rotary kiln or a new dry kiln, the cement strength grade is not less than 52.5 or 42.5; the cement alkali content does not exceed 0.6% of the cement mass, and the cement specific surface area is between 300 and 350 m 2 / kg;

[0012] The present invention adopts silicate cement and complies with the requirements of "Technical Specifications for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and "Silica Cement, Ordinary Silicon Cement" (GB175); the strength grade of cement used in C55 concrete should be not less than 52.5 or 42.5; cement is preferably silicate cement or ordinary silicate cement produced by a rotary kiln with a strength grade of not less than 42.5. The reason why the fineness is particularly required is that the finer the cement is ground, the larger the specific surface area, the more complete the hydration reaction, and the higher the early strength. However, it should be noted that the fineness should not be too high, otherwise it will cause excessive hydration heat, resulting in cracks in the concrete, which will reduce the later strength and durability of the concrete.

[0013] Too high alkali content in cement will trigger alkali-aggregate reaction, causing concrete expansion and cracking, affecting the durability of the structure. Limiting the alkali content to no more than 0.6% of the cement mass can effectively reduce this risk. Although cement with too large a specific surface area can improve early strength, it will increase costs. Cement with too small a specific surface area may affect the performance of concrete. Choose 300-350m 2 / kg specific surface area can balance performance and economy.

[0014] The fly ash used is of Class F II and above as specified in the current national standard GB / T1596 "Fly ash used in cement and concrete". The workability of concrete is improved after adding fly ash. Adding an appropriate amount of fly ash can improve the fluidity, cohesion and water retention of concrete mixtures, making the concrete mixtures easier to pump and cast, and can reduce the loss of concrete over time.

[0015] The use of mineral powder can reduce the amount of cement, improve the workability of concrete, reduce the hydration heat, increase the later strength of concrete, improve the internal structure of concrete, and improve the anti-seepage and anti-corrosion capabilities. The addition of mineral powder to concrete can delay the hydration rate of cementitious materials and extend the setting time of concrete. This property is beneficial to the transportation and construction of concrete in high temperature seasons. The present invention uses ground blast furnace slag powder with a Blaine specific surface area of ​​not less than 350m 2 / kg, not exceeding 450m 2 / kg, loss on ignition is not more than 3%;

[0016] Silica fume has a significant effect on improving the chemical corrosion resistance of concrete, but due to its high activity, it is not conducive to reducing temperature deformation and will also increase concrete shrinkage. Therefore, silica fume should be used in combination with other mineral admixtures. The silica content in silica fume is ≥85%, and the Blaine specific surface area is ≥18000m 2 / kg, densification silica fume is preferred, the amount of silica fume should not exceed 8% of the total amount of cementitious materials, and it should be used in combination with other mineral admixtures. When used in large-volume concrete, the amount should be reduced;

[0017] The present invention utilizes the water-reducing effect of admixtures such as fly ash, and appropriately lowers the water-binder ratio of concrete with a large amount of mineral admixtures (the water-binder ratio refers to the mass ratio of water to cementitious materials in concrete), so as to prepare concrete with strength that meets engineering requirements and better pumpability. In particular, for pumping concrete with a high pumping height, it is recommended to use a larger amount of fly ash or a composite method of fly ash with granulated blast furnace slag powder and silica fume to ensure the pumpability of the concrete.

[0018] S2. Obtaining environmental and process parameters, which include pipeline parameters, environmental parameters, pumping height, pumping speed of the concrete delivery pump, and pumping length, and inputting the environmental and process parameters into a pre-built required viscosity prediction model to obtain the required viscosity of the concrete corresponding to the environmental and process parameters;

[0019] It is necessary to select and consider pipeline parameters, environmental parameters, pumping height, pumping speed of concrete pumps and pumping length, because these parameters jointly determine the required viscosity of concrete. Comprehensive consideration of these parameters can ensure the stability and smoothness of concrete during pumping, avoid pumping difficulties and pump blockage problems, improve construction efficiency and safety, and ensure the final construction quality;

[0020] S3, inputting the proportions of cement, coarse aggregate, fine aggregate, fly ash, mineral powder, silica fume, water and water reducing agent into a pre-constructed concrete viscosity prediction model to obtain a predicted concrete viscosity;

[0021] S4. Compare the required viscosity with the predicted viscosity of the concrete; if the predicted viscosity of the concrete is less than the required viscosity, the concrete of this component can be pumped; if the predicted viscosity of the concrete is greater than the required viscosity, the concrete of this component cannot be pumped, and the concrete component is adjusted.

[0022] As a preferred embodiment of the present invention, the method for adjusting the concrete components comprises:

[0023] S41, performing correlation analysis on the predicted viscosity of concrete to quantify the viscosity contribution value of each concrete component;

[0024] S42, using the viscosity contribution value as a queue node to construct a concrete component optimization priority queue;

[0025] S43, selecting the queue node at the top of the concrete component optimization priority queue for adjustment;

[0026] S44, calculating concrete viscosity according to the adjusted queue node, comparing the concrete viscosity with the required viscosity, and outputting the adjusted concrete component if the concrete viscosity is less than the required viscosity;

[0027] S45. If the concrete viscosity is greater than or equal to the required viscosity, the concrete component optimization priority queue is updated, and the adjustment of the concrete components is repeated until the concrete viscosity is less than the required viscosity.

[0028] The traditional trial and error method requires multiple experiments to find the appropriate component ratio. Correlation analysis is based on a large amount of experimental data and statistical methods, which can scientifically determine the degree of influence of each component on the viscosity of concrete. By quantifying the influence of each component on the viscosity, the component ratio can be accurately adjusted to ensure that the viscosity of the concrete reaches the required value.

[0029] As a preferred embodiment of the present invention, the fine aggregate is river sand or machine-made sand, and the coarse aggregate is crushed stone or pebbles;

[0030] The particle size and gradation of fine and coarse aggregates have a great influence on the pumping performance of concrete and must be strictly controlled;

[0031] The quality of fine aggregate has a greater impact on the workability of C55 concrete than coarse aggregate. Sand with good grading and low mud content should be selected first. The selected sand should comply with the provisions of JGJ / T10-2011 "Technical Specification for Concrete Pumping Construction". Fine aggregate should be medium sand with a fineness modulus of 2.8 to 3.1. The proportion of fine aggregate with a particle size of less than 0.315 mm should be no less than 15% according to the standard requirements, the stone powder content should be ≤12%, and the methylene blue content should be <1.0. Fine aggregate should be graded sand in Zone II, and the sand should be strictly controlled. It is forbidden to use fine aggregates with alkali activity; the fineness modulus is within the above range to ensure that the concrete has good workability and density; the proportion of fine aggregates with a particle size of less than 0.315mm is not less than 15% according to the standard requirements, which can ensure the fluidity of the concrete and reduce the phenomenon of stratification and segregation; too high a content of stone powder will affect the workability and strength of the concrete; the methylene blue value reflects the content of clay and organic matter in the fine aggregate. A low methylene blue value indicates that the fine aggregate is highly clean, which is beneficial to the performance of the concrete;

[0032] Coarse aggregate plays a major role as a skeleton in the structure of concrete. The compressive strength, surface characteristics, maximum particle size, impurity content and other properties of coarse aggregate have an important influence on the strength of C55 concrete.

[0033] The particle size distribution of the coarse aggregate selected in the present invention is shown in Table 1;

[0034] Table 1

[0035]

[0036] The correlation between the maximum particle size of coarse aggregate in pumped concrete and the minimum inner diameter of the concrete delivery pipe is shown in Table 2;

[0037] Table 2

[0038]

[0039] The technical performance test method of coarse aggregate complies with the relevant provisions of the current national standard "Pebble and Crushed Stone for Construction" GB / T14685 and "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete" JGJ52.

[0040] As a preferred solution of the present invention, when the concrete delivery pipe is arranged vertically upward, the converted length of the ground horizontal pipe is greater than or equal to 1 / 5 of the length of the vertical pipe, and greater than or equal to 15m;

[0041] When the length of the horizontal pipe is 1 / 5 of the length of the vertical pipe, the pumping resistance can be effectively reduced, ensuring that the concrete has good fluidity and uniformity before entering the vertical pipe. At the same time, a gentler pressure gradient can be formed, reducing the sudden pressure change during the pumping process and reducing the load on the pumping system.

[0042] When pumping is carried out at an angle or vertically downward, and the height difference is greater than 20m, a bend or horizontal pipe is set at the lower end of the inclined or vertical pipe. The converted length of the bend and horizontal pipe is greater than or equal to 1.5 times the height difference. The horizontal pipe and the bend can reduce the pumping resistance and improve the pumping efficiency. The horizontal pipe and the bend can reduce the occurrence of air plugging and improve the stability of pumping. The horizontal pipe and the bend can disperse the pumping pressure and reduce the pressure concentration in the vertical pipe section. According to the practical experience of fluid mechanics and concrete pumping, the converted length of the horizontal pipe and the bend should be at least 1.5 times the height difference to ensure the stability and efficiency of the pumping process. When the length of the horizontal pipe and the bend is 1.5 times the height difference, the pumping resistance can be effectively reduced to ensure that the concrete has good fluidity and uniformity before entering the vertical pipe. It can also form a smoother pressure gradient, reduce the pressure mutation during the pumping process, and reduce the load on the pumping system.

[0043] As a preferred solution of the present invention, the pipeline parameters include: pipeline diameter, pipeline length, pipeline material, pipeline bending times and angles;

[0044] Environmental parameters include ambient temperature and humidity;

[0045] The pipe diameter directly affects the flow resistance and pumping pressure of concrete. A larger pipe diameter can reduce the flow resistance and improve the fluidity of concrete. A smaller pipe diameter will increase the flow resistance and require a higher pumping pressure. Choose the appropriate pipe diameter based on the pumping height and distance. Commonly used diameters are 100mm, 125mm, and 150mm.

[0046] The length of the pipeline affects the flow resistance and pumping pressure of concrete. Longer pipelines increase the flow resistance and require higher pumping pressure. Longer pipelines cause the temperature of concrete in the pipeline to change, affecting the performance of concrete.

[0047] Different pumping heights require different pipe lengths and different concrete mix ratios. The designed mix ratio must meet the strength and durability requirements specified in the design, and must also ensure that the concrete has good pumpability. The pumped concrete mixture has good workability, less water seepage, less friction resistance, no segregation, and no pipe clogging.

[0048] In order to ensure the optimal performance of high-altitude pumped concrete at different heights, the present invention divides the concrete mix ratio into four stages of design; different mix ratios are selected in each stage according to different pumping heights to adapt to the construction requirements of different heights; the details are as follows:

[0049] Stage 1 (0-60m): Pure cement mix ratio is used, and the concrete has good early strength and workability, which is suitable for pumping at low heights;

[0050] The second stage (60-150m): adopt a single fly ash mix ratio, and improve the workability and durability of concrete by adding fly ash, which is suitable for pumping at medium heights;

[0051] The third stage (150-200m): the use of double fly ash, mineral powder or fly ash, silica fume mix ratio, by adding two admixtures to further improve the strength and durability of concrete, suitable for higher height section pumping;

[0052] The fourth stage (above 200m): adopt the three-mixed fly ash, mineral powder and silica fume mix ratio, and maximize the comprehensive performance of concrete by adding three admixtures to ensure the pumping effect of the ultra-high height section;

[0053] By designing the mix ratio of concrete in stages, we can effectively cope with the construction challenges of different height sections, ensure the optimal performance of concrete during the pumping process, and achieve efficient, safe and high-quality construction; pipes of different materials have different friction coefficients on concrete, which affects the pumping efficiency. Smooth pipes (such as steel pipes) can reduce friction and improve pumping efficiency. Different pipe materials have different durability. Commonly used pipe materials include steel pipes and plastic pipes. Choose the appropriate material according to the project requirements;

[0054] The number and angle of pipe bends will affect the fluidity and pumping pressure of concrete. Excessive bends will increase flow resistance and require higher pumping pressure. Air plugs are easily generated at bends, affecting pumping stability.

[0055] Ambient temperature affects the hydration rate and fluidity of concrete. High temperature will accelerate the hydration reaction, which may cause the concrete to solidify prematurely and affect pumping. Low temperature will delay the hydration reaction and may affect the early strength of concrete.

[0056] Ambient humidity affects the evaporation rate and workability of concrete. High humidity can slow down the evaporation of water and maintain the fluidity of concrete, while low humidity will accelerate the evaporation of water and affect the workability of concrete.

[0057] As a preferred embodiment of the present invention, the components in step S1 further include an admixture, and the admixture is one or more of gypsum, phosphogypsum, desulfurized gypsum, red mud, metakaolin, nano-silicon dioxide and nano-calcium carbonate;

[0058] Gypsum, phosphogypsum and desulfurized gypsum can delay the setting time of cement, so that the concrete maintains good fluidity during pumping;

[0059] Red mud, metakaolin, nano-silica and nano-calcium carbonate can improve the workability of concrete, making it easier to mix and pump, increase the early and late strength of concrete, improve the durability of concrete, and reduce the risk of cracking and corrosion;

[0060] As a preferred embodiment of the present invention, a method for constructing a desired viscosity prediction model is as follows:

[0061] S21. Collect historical data, including pumping height, total pumping length, pumping speed, pipeline parameters, environmental parameters, and concrete viscosity corresponding to the above parameters;

[0062] S22, clean the data and deal with missing values ​​and outliers;

[0063] S23, performing feature processing on the historical data to obtain historical feature data, and dividing the historical feature data into a training set and a test set;

[0064] As a preferred solution of the present invention, feature processing is performed on historical data, including:

[0065] S231, dividing the historical data into continuous data and discrete data;

[0066] S232, normalizing the continuous data to obtain a continuous variable, and encoding the discrete data to obtain a discrete variable;

[0067] S233. Merge the continuous variables and the discrete variables to obtain historical characteristic data.

[0068] S24. Select a suitable machine learning model, train the machine learning model using training set data, and adjust the machine learning model parameters to obtain optimal performance;

[0069] S25. Use the test set data to verify the predictive performance of the model.

[0070] By collecting and cleaning historical data, standardizing or normalizing the data, and using appropriate machine learning models for training and verification, an accurate concrete viscosity prediction model can be constructed. This model can accurately predict the viscosity of concrete based on inputs such as pumping height, total pumping length, pumping speed, pipeline parameters, and environmental parameters, thereby significantly improving pumping efficiency and stability, reducing failure rates and downtime during pumping, optimizing the fluidity and workability of concrete, reducing material waste, adapting to different construction conditions, ensuring construction quality and safety, and ultimately achieving efficient, safe, and high-quality construction. It has important scientific and economic value and provides strong technical support for modern engineering construction.

[0071] As a preferred embodiment of the present invention, a method for constructing a concrete viscosity prediction model comprises:

[0072] S31, collecting historical concrete viscosity and component ratio data under the concrete viscosity;

[0073] S32, cleaning the data, removing outliers and missing values, and dividing the data into a training set and a test set;

[0074] S33, select input feature: proportion of various components of concrete; select output feature: viscosity of concrete;

[0075] S34. Select a suitable machine learning model, use the training set data to train the machine learning model, and adjust the machine learning model parameters to obtain the best performance;

[0076] S35. Use the test set data to verify the predictive performance of the model.

[0077] By collecting and cleaning historical concrete viscosity and its corresponding component ratio data, removing outliers and missing values, and dividing the data into training sets and test sets, the various component ratios of concrete are selected as input features, and concrete viscosity is selected as output features. A suitable machine learning model is used for training and parameter adjustment, and finally the prediction performance of the model is verified through the test set data. This method can accurately predict the viscosity of concrete, significantly improve pumping efficiency and stability, reduce failure rate and downtime during pumping, optimize the fluidity and workability of concrete, reduce material waste, adapt to different construction conditions, ensure construction quality and safety, and ultimately achieve efficient, safe, and high-quality construction. It has important scientific and economic value and provides strong technical support for modern engineering construction.

[0078] As a preferred solution of the present invention, after the concrete pump is started, an appropriate amount of clean water is first pumped to wet the part directly in contact with the concrete, and after the pumping is completed, the water accumulated in the pump is cleared;

[0079] After checking with clean water and confirming that there are no foreign objects in the concrete pump and delivery pipe, use cement paste or 1:2 cement mortar or concrete mortar with the same mix ratio as other components in concrete except coarse aggregate to lubricate the concrete pump and the inner wall of the delivery pipe;

[0080] This method can effectively ensure the cleanliness and lubrication of the pumping system, reduce resistance and wear during the pumping process, improve pumping efficiency and stability, prevent stratification and pipe blockage of concrete during pumping, ensure construction quality and safety, thereby achieving efficient, safe and high-quality construction, reducing failures and downtime during construction, and improving construction efficiency and economic benefits.

[0081] Compared with the prior art, the present invention has the following beneficial effects:

[0082] Through the required viscosity prediction model, multiple factors such as pipeline parameters, environmental parameters, pumping height, pumping speed and pumping length are comprehensively considered, and the required concrete viscosity under specific construction conditions can be accurately predicted. By predicting the required viscosity in advance, the construction party can formulate a construction plan more scientifically, select appropriate pumping equipment and construction parameters, and avoid pumping problems caused by excessively high or low viscosity; through the prediction of the concrete viscosity prediction model, the required viscosity can be quickly adapted by adjusting the concrete component ratio, which is fast and efficient; the present invention can predict the viscosity of concrete under different ratios and the required viscosity under the condition of determined environmental and process parameters, and effectively solve the common problems of excessive pump pressure, pumping difficulties and pump blockage in elevation pumping concrete engineering, which not only improves construction efficiency and safety, but also ensures construction quality, adapts to pumping needs at different heights, and provides strong technical support for achieving efficient, safe and high-quality construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0084] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0085] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0086] Secondly, the term "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0087] Reference Figure 1 This embodiment provides a design method for optimizing concrete fluidity by viscosity regulation, comprising the following steps:

[0088] S1. Determine the required strength grade of concrete according to industry standards, and determine the proportion range of each component of the required concrete according to the strength grade, the components include cement, coarse aggregate, fine aggregate, fly ash, mineral powder, silica fume, water and water reducing agent;

[0089] Specifically, industry standards can adopt GB / T 50164 "Concrete Quality Control Standard" or ASTM C94 "Standard Specification for Concrete" to determine the concrete strength grade required for the project;

[0090] By determining the required proportion range of each component of concrete in advance, it can be ensured that when adjusted within these ranges, the strength of the concrete still meets the predetermined indicators. For example, by adjusting the proportion of cement, coarse aggregate, fine aggregate, etc., other properties (such as fluidity and workability) can be optimized while ensuring strength.

[0091] Cement is the main cementing material of concrete. It forms a solid gel through hydration reaction, giving concrete strength and durability.

[0092] The cement used is low hydration heat, low alkali content silicate cement or ordinary silicate cement produced by large-scale rotary kiln or new dry kiln. The cement strength grade is not less than 52.5 or 42.5; the cement alkali content does not exceed 0.6% of the cement mass, and the cement specific surface area is between 300 and 350 m 2 / kg;

[0093] Too high alkali content in cement will trigger alkali-aggregate reaction, causing concrete expansion and cracking, affecting the durability of the structure. Limiting the alkali content to no more than 0.6% of the cement mass can effectively reduce this risk. Although cement with too large a specific surface area can improve early strength, it will increase costs. Cement with too small a specific surface area may affect the performance of concrete. Choose 300-350m 2 The specific surface area of ​​​​ / kg can balance performance and economy;

[0094] Different pumping heights require different pipe lengths and different concrete mix ratios. The designed mix ratio must meet the strength and durability requirements specified in the design, and must also ensure that the concrete has good pumpability. The pumped concrete mixture has good workability, less water seepage, less friction resistance, no segregation, and no pipe clogging.

[0095] In order to ensure the optimal performance of high-altitude pumped concrete at different heights, the present invention divides the concrete mix ratio into four stages of design; different mix ratios are selected in each stage according to different pumping heights to adapt to the construction requirements of different heights; the details are as follows:

[0096] Stage 1 (0-60m): Pure cement mix ratio is used, and the concrete has good early strength and workability, which is suitable for pumping at low heights;

[0097] The second stage (60-150m): adopt a single fly ash mix ratio, and improve the workability and durability of concrete by adding fly ash, which is suitable for pumping at medium heights;

[0098] The third stage (150-200m): the use of double fly ash, mineral powder or fly ash, silica fume mix ratio, by adding two admixtures to further improve the strength and durability of concrete, suitable for higher height section pumping;

[0099] The fourth stage (above 200m): adopt the three-mixed fly ash, mineral powder and silica fume mix ratio, and maximize the comprehensive performance of concrete by adding three admixtures to ensure the pumping effect of the ultra-high height section;

[0100] By designing the concrete mix ratio in stages, we can effectively cope with the construction challenges at different heights, ensure the best performance of concrete during pumping, and achieve efficient, safe and high-quality construction.

[0101] S2. Obtaining environmental and process parameters, which include pipeline parameters, environmental parameters, pumping height, pumping speed of the concrete delivery pump, and pumping length, and inputting the environmental and process parameters into a pre-built required viscosity prediction model to obtain the required viscosity of the concrete corresponding to the environmental and process parameters;

[0102] Specifically, it is necessary to select and consider pipeline parameters, environmental parameters, pumping height, pumping speed of concrete pumps, and pumping length, because these parameters jointly determine the required viscosity of concrete. Comprehensive consideration of these parameters can ensure the stability and smoothness of concrete during the pumping process, avoid pumping difficulties and pump blockage problems, improve construction efficiency and safety, and ensure the final construction quality;

[0103] Pipeline parameters include: pipe diameter, pipe length, pipe material, pipe bending times and angles;

[0104] Environmental parameters include ambient temperature and humidity;

[0105] The pipe diameter directly affects the flow resistance and pumping pressure of concrete. A larger pipe diameter can reduce the flow resistance and improve the fluidity of concrete. A smaller pipe diameter will increase the flow resistance and require a higher pumping pressure. Choose the appropriate pipe diameter based on the pumping height and distance. Commonly used diameters are 100mm, 125mm, and 150mm.

[0106] The length of the pipeline affects the flow resistance and pumping pressure of concrete. Longer pipelines increase the flow resistance and require higher pumping pressure. Longer pipelines cause the temperature of concrete in the pipeline to change, affecting the performance of concrete.

[0107] Pipes made of different materials have different friction coefficients on concrete, which affects pumping efficiency. Smooth pipes (such as steel pipes) can reduce friction and improve pumping efficiency. Different pipe materials have different durability. Commonly used pipe materials include steel pipes and plastic pipes. Choose the appropriate material according to project requirements.

[0108] The number and angle of pipe bends will affect the fluidity and pumping pressure of concrete. Excessive bends will increase flow resistance and require higher pumping pressure. Air plugs are easily generated at bends, affecting pumping stability.

[0109] Ambient temperature affects the hydration rate and fluidity of concrete. High temperature will accelerate the hydration reaction, which may cause the concrete to solidify prematurely and affect pumping. Low temperature will delay the hydration reaction and may affect the early strength of concrete.

[0110] Ambient humidity affects the evaporation rate and workability of concrete. High humidity can slow down the evaporation of water and maintain the fluidity of concrete, while low humidity will accelerate the evaporation of water and affect the workability of concrete.

[0111] When calculating the pumping length, the pipeline layout rules are as follows: when the concrete delivery pipe is piped vertically upward, the converted length of the ground horizontal pipe is greater than or equal to 1 / 5 of the vertical pipe length, and greater than or equal to 15m; when the length of the horizontal pipe is 1 / 5 of the vertical pipe length, it can effectively reduce the pumping resistance and ensure that the concrete has good fluidity and uniformity before entering the vertical pipe. At the same time, it can form a gentler pressure gradient, reduce the sudden pressure change during the pumping process, and reduce the load of the pumping system; when the inclined or vertical downward pumping construction is carried out, and the height difference is greater than 20m, a bend or horizontal pipe is set at the lower end of the inclined or vertical pipe, and the converted length of the bend and horizontal pipe is greater than or equal to 1.5 times the height difference, and the horizontal pipe is Pipes and elbows can reduce pumping resistance and improve pumping efficiency. Horizontal pipes and elbows can reduce the occurrence of air plugging and improve pumping stability. Horizontal pipes and elbows can disperse pumping pressure and reduce pressure concentration in vertical pipe sections. According to the practical experience of fluid mechanics and concrete pumping, the converted length of horizontal pipes and elbows should be at least 1.5 times the height difference to ensure the stability and efficiency of the pumping process. When the length of horizontal pipes and elbows is 1.5 times the height difference, it can effectively reduce pumping resistance and ensure that the concrete has good fluidity and uniformity before entering the vertical pipe. It can also form a gentler pressure gradient, reduce sudden pressure changes during pumping, and reduce the load on the pumping system.

[0112] Method for constructing a model to predict the required viscosity,

[0113] S21. Collect historical data, including pumping height, total pumping length, pumping speed, pipeline parameters, environmental parameters, and concrete viscosity corresponding to the above parameters;

[0114] S22, clean the data and deal with missing values ​​and outliers;

[0115] S23, performing feature processing on the historical data to obtain historical feature data, and dividing the historical feature data into a training set and a test set;

[0116] As a preferred solution of the present invention, feature processing is performed on historical data, including:

[0117] S231, dividing historical data into continuous data and discrete data;

[0118] S232, normalizing the continuous data to obtain a continuous variable, and encoding the discrete data to obtain a discrete variable;

[0119] S233. Merge the continuous variables and the discrete variables to obtain historical characteristic data.

[0120] Specifically, in order to normalize different types of features, it is possible to clarify whether the collected historical data is continuous data or discrete data. The numerical range of continuous data is continuous, such as pumping height, pumping speed, etc., while discrete data has finite categories or integers, such as pipeline material, weather type, etc.; normalizing continuous data can scale the value range of continuous data to [0,1] or other ranges to ensure that the numerical scales of different features are consistent; encoding discrete data can convert each category into a binary feature; in order to make the data have a consistent numerical format, all variables are represented in a way that the machine learning model can understand. The normalized continuous variables and the encoded discrete variables can be merged by column to keep the data structure consistent. The processed data will contain unified numerical features for subsequent modeling or analysis.

[0121] S24. Select a suitable machine learning model, train the machine learning model using training set data, and adjust the machine learning model parameters to obtain optimal performance;

[0122] S25. Use the test set data to verify the predictive performance of the model.

[0123] By collecting and cleaning historical data, standardizing or normalizing the data, and using appropriate machine learning models for training and verification, an accurate concrete viscosity prediction model can be constructed. This model can accurately predict the viscosity of concrete based on inputs such as pumping height, total pumping length, pumping speed, pipeline parameters, and environmental parameters, thereby significantly improving pumping efficiency and stability, reducing failure rates and downtime during pumping, optimizing the fluidity and workability of concrete, reducing material waste, adapting to different construction conditions, ensuring construction quality and safety, and ultimately achieving efficient, safe, and high-quality construction. It has important scientific and economic value and provides strong technical support for modern engineering construction;

[0124] S3, inputting the proportions of cement, coarse aggregate, fine aggregate, fly ash, mineral powder, silica fume, water and water reducing agent into a pre-constructed concrete viscosity prediction model to obtain a predicted concrete viscosity;

[0125] Specifically, the method for constructing the concrete viscosity prediction model includes:

[0126] S31, collecting historical concrete viscosity and component ratio data under the concrete viscosity;

[0127] S32, cleaning the data, removing outliers and missing values, and dividing the data into a training set and a test set;

[0128] S33, select input feature: proportion of various components of concrete; select output feature: viscosity of concrete;

[0129] S34. Select a suitable machine learning model, use the training set data to train the machine learning model, and adjust the machine learning model parameters to obtain the best performance;

[0130] S35. Use the test set data to verify the predictive performance of the model.

[0131] By collecting and cleaning historical concrete viscosity and its corresponding component ratio data, removing outliers and missing values, and dividing the data into training sets and test sets, the various component ratios of concrete are selected as input features, and concrete viscosity is selected as output features. A suitable machine learning model is used for training and parameter adjustment, and finally the prediction performance of the model is verified through the test set data. This method can accurately predict the viscosity of concrete, significantly improve pumping efficiency and stability, reduce failure rate and downtime during pumping, optimize the fluidity and workability of concrete, reduce material waste, adapt to different construction conditions, ensure construction quality and safety, and ultimately achieve efficient, safe, and high-quality construction. It has important scientific and economic value and provides strong technical support for modern engineering construction;

[0132] S4, comparing the required viscosity with the predicted viscosity of the concrete; if the predicted viscosity of the concrete is less than the required viscosity, the concrete of this component can be pumped;

[0133] Before pumping concrete in large quantities, the following operations should be performed: After starting the concrete pump, first pump an appropriate amount of clean water to wet the parts that are in direct contact with the concrete. After pumping, remove the water in the pump; after checking with clean water and confirming that there are no foreign objects in the concrete pump and delivery pipe, use cement paste or 1:2 cement mortar or concrete mortar with the same mix ratio as other components in the concrete except coarse aggregate to lubricate the concrete pump and the inner wall of the delivery pipe;

[0134] This method can effectively ensure the cleanliness and lubrication of the pumping system, reduce resistance and wear during the pumping process, improve pumping efficiency and stability, prevent concrete from stratification and pipe blockage during the pumping process, ensure construction quality and safety, thereby achieving efficient, safe and high-quality construction, reducing failures and downtime during construction, and improving construction efficiency and economic benefits.

[0135] If the predicted viscosity of the concrete is greater than the required viscosity, the concrete under this component cannot be pumped, and the concrete components should be adjusted;

[0136] Methods for adjusting concrete components include:

[0137] S41, performing correlation analysis on the predicted viscosity of concrete to quantify the viscosity contribution of each concrete component;

[0138] S42, using the viscosity contribution value as a queue node to construct a concrete component optimization priority queue;

[0139] S43, selecting the top queue node of the concrete component optimization priority queue for adjustment;

[0140] S44, calculating the concrete viscosity according to the adjusted queue node, comparing the concrete viscosity with the required viscosity, and outputting the adjusted concrete component if the concrete viscosity is less than the required viscosity;

[0141] S45. If the concrete viscosity is greater than or equal to the required viscosity, the concrete component optimization priority queue is updated, and the adjustment of the concrete components is repeated until the concrete viscosity is less than the required viscosity.

[0142] As a preferred embodiment of this embodiment, in order to find out the component that has the greatest impact on the viscosity of concrete and make a priority adjustment, the contribution of each component to the viscosity can be quantified through correlation analysis, such as linear correlation coefficient, partial correlation analysis, etc. The viscosity contribution values ​​of all components are used as the priority basis to build a component optimization priority queue. The higher the priority of the component, the more significant the impact on the viscosity. The optimally adjusted component is at the top of the queue and is adjusted first. According to the component optimization priority queue, its proportion can be optimized starting from the optimally adjusted component, gradually approaching the target viscosity, recalculating the viscosity contribution value after each adjustment, and dynamically updating the priority model until the viscosity meets the design requirements. This embodiment introduces a priority queue to improve the adjustment efficiency, avoid disorderly adjustment of components, and reduce the cost of trial and error. At the same time, a queue dynamic update mechanism is introduced to recalculate the priority queue after each round of adjustment to ensure that the optimization direction is always based on the latest viscosity state, adapt to complex component interactions, and make the optimization results closer to the target.

[0143] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A design method for optimizing concrete fluidity by viscosity control, characterized in that: The following steps are involved: S1. Determine the required strength grade of concrete according to industry standards, and determine the proportion range of each component of the required concrete according to the strength grade, the components include cement, coarse aggregate, fine aggregate, fly ash, mineral powder, silica fume, water and water reducing agent; S2. Obtaining environmental and process parameters, which include pipeline parameters, environmental parameters, pumping height, pumping speed of the concrete delivery pump, and pumping length, and inputting the environmental and process parameters into a pre-built required viscosity prediction model to obtain the required viscosity of the concrete corresponding to the environmental and process parameters; S3, inputting the proportions of cement, coarse aggregate, fine aggregate, fly ash, mineral powder, silica fume, water and water reducing agent into a pre-constructed concrete viscosity prediction model to obtain a predicted concrete viscosity; S4. Compare the required viscosity with the predicted viscosity of the concrete; if the predicted viscosity of the concrete is less than the required viscosity, the concrete of this component can be pumped; if the predicted viscosity of the concrete is greater than the required viscosity, the concrete of this component cannot be pumped, and the concrete component is adjusted.

2. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: The cement used is low hydration heat, low alkali content silicate cement or ordinary silicate cement produced by large-scale rotary kiln or new dry kiln, the cement strength grade is not less than 52.5 or 42.5; the cement alkali content does not exceed 0.6% of the cement mass, and the cement specific surface area is between 300 and 350 m 2 / kg.

3. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: The method for adjusting the concrete components comprises: S41, performing correlation analysis on the predicted viscosity of concrete to quantify the viscosity contribution value of each concrete component; S42, using the viscosity contribution value as a queue node to construct a concrete component optimization priority queue; S43, selecting the queue node at the top of the concrete component optimization priority queue for adjustment; S44, calculating concrete viscosity according to the adjusted queue node, comparing the concrete viscosity with the required viscosity, and outputting the adjusted concrete component if the concrete viscosity is less than the required viscosity; S45. If the concrete viscosity is greater than or equal to the required viscosity, the concrete component optimization priority queue is updated, and the adjustment of the concrete components is repeated until the concrete viscosity is less than the required viscosity.

4. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: The fine aggregate is river sand or machine-made sand, and the coarse aggregate is crushed stone or pebbles.

5. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: When the concrete delivery pipe is installed vertically upward, the converted length of the ground horizontal pipe shall be greater than or equal to 1 / 5 of the length of the vertical pipe and greater than or equal to 15m; When pumping is carried out at an angle or vertically downwards, and the height difference is greater than 20m, a bend or horizontal pipe shall be installed at the lower end of the inclined or vertical pipe, and the converted length of the bend and horizontal pipe shall be greater than or equal to 1.5 times the height difference.

6. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: The pipeline parameters include: pipeline diameter, pipeline length, pipeline material, pipeline bending times and angles; The environmental parameters include ambient temperature and humidity.

7. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: The components in step S1 also include an admixture, and the admixture is one or more of gypsum, phosphogypsum, desulfurized gypsum, red mud, metakaolin, nano-silicon dioxide and nano-calcium carbonate.

8. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: The method for constructing the required viscosity prediction model, S21. Collect historical data, where the historical data includes pumping height, total pumping length, pumping speed, pipeline parameters, environmental parameters, and concrete viscosity corresponding to the above parameters; S22, clean the data and deal with missing values ​​and outliers; S23, performing feature processing on the historical data to obtain historical feature data, and dividing the historical feature data into a training set and a test set; S24. Select a suitable machine learning model, train the machine learning model using training set data, and adjust the machine learning model parameters to obtain optimal performance; S25. Use the test set data to verify the predictive performance of the model.

9. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 8, characterized in that: The feature processing of the historical data includes: S231, dividing the historical data into continuous data and discrete data; S232, normalizing the continuous data to obtain a continuous variable, and encoding the discrete data to obtain a discrete variable; S233. Merge the continuous variables and the discrete variables to obtain historical characteristic data.

10. The design method for optimizing concrete fluidity by viscosity control as claimed in claim 1, characterized in that: After starting the concrete pump, first pump an appropriate amount of clean water to wet the parts that are in direct contact with the concrete. After pumping is completed, clear the water in the pump. After checking with clean water and confirming that there are no foreign objects in the concrete pump and delivery pipe, use cement paste or 1:2 cement mortar or concrete mortar with the same mix ratio as other components in concrete except coarse aggregate to lubricate the concrete pump and the inner wall of the delivery pipe.

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