Rapid detection method for fluctuation of water consumption of fresh concrete

Abstract

The invention provides a rapid detection method for water consumption fluctuation of fresh concrete. Separating the dried freshly mixed concrete by adopting a slurry-aggregate process, and obtaining the actual mass of each component; by correcting the initial water-binder ratio twice, errors caused by the content of coarse and fine aggregate mud powder, the mixing amount of an additive and the solid content of the additive to the calculation of the water-binder ratio of fresh concrete are eliminated. According to the method, the real-time water-binder ratio of the fresh concrete can be accurately calculated, the operation is simple, and a guarantee is provided for improving concrete quality control in the construction process.

Description

Technical Field

[0001] This invention belongs to the field of building engineering technology, specifically relating to a rapid detection method for fluctuations in the water content of freshly mixed concrete. Background Technology

[0002] Concrete, as one of the most important building materials in modern construction engineering, directly affects the safety and durability of building structures. During concrete structure construction, controlling the water-cement ratio of fresh concrete is a key factor in ensuring concrete performance. However, in actual engineering applications, due to multiple factors such as transportation time, changes in ambient temperature and humidity, and on-site construction adjustments, the actual water-cement ratio of fresh concrete often deviates significantly from the design mix proportion. This deviation leads to a significant decrease in the workability, mechanical properties, and durability of concrete, seriously affecting project quality. Fresh concrete required for concrete structure construction is usually produced and transported by commercial concrete batching plants or on-site concrete batching plants. Both of these batching plants produce concrete according to the specific concrete mix proportions provided for the project, with variations in the water-cement ratio for different grades of concrete. However, the water-cement ratio of fresh concrete changes with factors such as pouring time, ambient temperature and humidity, and adjustments made by adding water during pouring. Therefore, the actual water-cement ratio of the concrete poured on-site differs from the design value in the concrete mix proportion, sometimes even differing significantly.

[0003] According to JGJ55-2011 "Specification for Mix Proportioning Design of Ordinary Concrete", the water-cement ratio of concrete is the mass ratio of water to cementitious materials in concrete. Water, as one of the raw materials of concrete, acts as a lubricant during the mixing process, giving the concrete mixture good flowability, facilitating pouring, vibration, and molding. Water can also undergo hydration reactions with the main mineral components in cement, producing hydrated calcium silicate gel and calcium hydroxide, which are the main sources of concrete strength. When there is too much water in the system, it causes aggregate and paste separation, resulting in aggregate settling and paste floating, severely affecting the subsequent strength development of the concrete. A higher water-cement ratio means that excess water, after evaporation, will leave pores inside the concrete, increasing porosity and severely affecting many properties of concrete, such as frost resistance, impermeability, and resistance to harmful chemical ions like sulfates. Furthermore, water evaporation causes concrete volume shrinkage, easily leading to drying shrinkage cracks, affecting the safety and service life of concrete components.

[0004] Therefore, to overcome the decline in concrete strength, impermeability, and durability caused by changes in the water-cement ratio, it is necessary to monitor the actual water-cement ratio of freshly mixed concrete during pouring. Considering that freshly mixed concrete contains cementitious materials such as cement, coarse and fine aggregates, water, and admixtures, effectively separating these raw materials and obtaining the mass of each component within a short time is crucial. Currently, the detection of concrete water-cement ratio mainly relies on the drying and weighing method under standard laboratory conditions. This method requires a long testing period and cannot meet the needs of real-time monitoring at construction sites. Furthermore, traditional methods struggle to accurately distinguish the influence of aggregate clay content and admixtures on the calculated water-cement ratio, leading to significant errors between the test results and the actual water-cement ratio. In addition, existing testing methods are complex to operate, requiring specialized equipment and personnel, making them difficult to implement quickly at construction sites. To address these issues, existing technologies urgently need improvement. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a rapid detection method for fluctuations in the water content of fresh concrete, which can accurately determine the real-time water-cement ratio of fresh concrete, is simple to operate, and provides assurance for improving concrete quality control during construction.

[0006] The first aspect of the present invention provides a rapid detection method for fluctuations in the water content of freshly mixed concrete, comprising the following steps:

[0007] (1) Sampling of fresh concrete: Take a section of fresh concrete with a mass of m1 that is being poured as the sample to be tested;

[0008] (2) Weighing after drying: The sample to be tested is dried until constant weight, then cooled to room temperature, and the mass of the dried sample to be tested is weighed and recorded as m2.

[0009] (3) Slurry-aggregate separation: Square hole sieves with diameters of 9.50 mm, 4.75 mm and 0.075 mm are used to separate slurry and aggregate in sequence: The sample to be tested with a mass of m2 is poured into the three nested sieves and rinsed with water. After rinsing, the aggregate filtered from each sieve is collected.

[0010] (4) Drying aggregates: Dry the collected aggregates again to constant weight, and after cooling to room temperature, weigh the coarse aggregates in the 9.50 mm square hole sieve and the 4.75 mm square hole sieve, and record the mass as M; weigh the fine aggregates in the 0.075 mm square hole sieve, and record the mass as m; record the total mass of coarse and fine aggregates as m3.

[0011] (5) Calculate the water-cement ratio: Calculate the initial water-cement ratio of the freshly mixed concrete sample according to formula (1), and record it as w / b;

[0012]

[0013] (6) First correction of water-cement ratio: Two parameters, coarse aggregate mud powder content α and fine aggregate mud powder content β, are introduced to make the first correction of the initial water-cement ratio. The water-cement ratio of the fresh concrete sample after the first correction is calculated according to formula (2) and recorded as w / b1.

[0014]

[0015] The mass m3 obtained in steps (3) and (4) above includes the mud content in the sand and gravel, that is, the initial water-cement ratio is slightly less than the actual water-cement ratio, so the initial water-cement ratio is corrected.

[0016] (7) Second correction of water-cement ratio: Two parameters, admixture dosage γ and admixture solid content ω, are introduced to make a second correction to the initial water-cement ratio. The water-cement ratio of the fresh concrete sample after the second correction is calculated according to formula (3) and denoted as w / b2.

[0017]

[0018] The water content (m1-m2) in the fresh concrete sample obtained in step (5) above includes admixtures, that is, the water-cement ratio after the first correction is slightly greater than the actual water-cement ratio, and the initial water-cement ratio needs to be corrected again.

[0019] The rapid detection method for water content fluctuation in freshly mixed concrete of this invention has at least the following beneficial effects:

[0020] This invention employs a slurry-aggregate process to separate freshly mixed concrete after drying, obtaining the actual mass of each component. By correcting the initial water-cement ratio twice, it eliminates errors in calculating the water-cement ratio of fresh concrete caused by the content of coarse and fine aggregates, the dosage of admixtures, and the solids content of admixtures. This method can accurately determine the real-time water-cement ratio of freshly mixed concrete, is simple to operate, and provides a guarantee for improving concrete quality control during construction.

[0021] According to some embodiments of the present invention, in step (1), m1 is 1kg-2kg.

[0022] According to some embodiments of the present invention, in step (2), the drying temperature is 100℃-110℃.

[0023] According to some embodiments of the present invention, in step (4), the sieve containing the aggregate is placed together with the aggregate into an oven for drying.

[0024] According to some embodiments of the present invention, in step (5), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is less than 5%, and no admixture is used or the admixture dosage is less than 0.5%, the initial water-cement ratio specified in step (5) is the actual value of the water-cement ratio of the sample.

[0025] According to some embodiments of the present invention, in step (6), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is greater than 5%, and no admixture is used or the admixture dosage is less than 0.5%, the first corrected water-cement ratio specified in step (6) is the actual value of the water-cement ratio of the sample.

[0026] According to some embodiments of the present invention, in step (6), the content of coarse aggregate mud powder α and the content of fine aggregate mud powder β can be obtained from the coarse and fine aggregate incoming inspection report.

[0027] According to some embodiments of the present invention, in step (7), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is greater than 5% and the admixture dosage is higher than 0.5%, the water-cement ratio specified in step (7) after the second correction is the actual value of the water-cement ratio of the sample.

[0028] According to some embodiments of the present invention, in step (7), the admixture dosage γ and the admixture solid content ω can be obtained from the admixture factory test report.

[0029] According to some embodiments of the present invention, the units of m1, m2, m3, M, and m are accurate to 1g. Detailed Implementation

[0030] In existing technologies, concrete structure construction relies on controlling the water-cement ratio of freshly mixed concrete. Traditional testing methods suffer from poor timeliness and complex operation. Commercial concrete batching plants produce concrete according to fixed mix proportions, but the water-cement ratio fluctuates during actual pouring due to environmental changes and human adjustments. Existing technologies struggle to quickly separate cementitious materials from aggregates, cannot accurately calculate the actual water-cement ratio, and lack dynamic correction mechanisms for aggregate mud powder content and the influence of admixtures. This leads to test results deviating from the true values, making it difficult to guide timely mix proportion adjustments.

[0031] To address these issues, researchers found that traditional testing methods, with cycles lasting several hours, could not meet the real-time monitoring needs of construction sites. Through observation, they discovered a regularity in the aggregate particle size distribution in freshly mixed concrete and attempted to establish a graded screening system to achieve paste-aggregate separation. To address the quality error caused by mud powder adhering to the aggregate surface, they proposed incorporating incoming inspection data for compensation and correction. Considering the interference of admixture solids content on moisture measurement, a secondary correction model was established to eliminate systematic errors, ultimately forming a technical approach combining staged treatment and dynamic correction.

[0032] In a first aspect, some embodiments of the present invention provide a rapid detection method for fluctuations in the water content of freshly mixed concrete, comprising the following steps: sampling the freshly mixed concrete and taking a specific mass of the sample to be tested; drying and weighing to remove free moisture; using a three-stage square-hole sieve for paste-aggregate separation, rinsing with water and collecting the aggregate; drying the aggregate a second time and weighing it separately; calculating the initial water-cement ratio and then correcting for the mud powder content and admixture parameters. Further, specifically including the following steps:

[0033] (1) Sampling of fresh concrete: Take a section of fresh concrete with a mass of m1 that is being poured as the sample to be tested;

[0034] (2) Weighing after drying: The sample to be tested is dried until constant weight, then cooled to room temperature, and the mass of the dried sample to be tested is weighed and recorded as m2.

[0035] (3) Slurry-aggregate separation: Square hole sieves with diameters of 9.50 mm, 4.75 mm and 0.075 mm are used to separate slurry and aggregate in sequence: The sample to be tested with a mass of m2 is poured into the three nested sieves and rinsed with water. After rinsing, the aggregate filtered from each sieve is collected.

[0036] (4) Drying aggregates: Dry the collected aggregates again to constant weight, and after cooling to room temperature, weigh the coarse aggregates in the 9.50 mm square hole sieve and the 4.75 mm square hole sieve, and record the mass as M; weigh the fine aggregates in the 0.075 mm square hole sieve, and record the mass as m; record the total mass of coarse and fine aggregates as m3.

[0037] (5) Calculate the water-cement ratio: Calculate the initial water-cement ratio of the freshly mixed concrete sample according to formula (1), and record it as w / b;

[0038]

[0039] (6) First correction of water-cement ratio: Two parameters, coarse aggregate mud powder content α and fine aggregate mud powder content β, are introduced to make the first correction of the initial water-cement ratio. The water-cement ratio of the fresh concrete sample after the first correction is calculated according to formula (2) and recorded as w / b1.

[0040]

[0041] The mass m3 obtained in steps (3) and (4) above includes the mud content in the sand and gravel, that is, the initial water-cement ratio is slightly less than the actual water-cement ratio, so the initial water-cement ratio is corrected.

[0042] (7) Second correction of water-cement ratio: Two parameters, admixture dosage γ and admixture solid content ω, are introduced to make a second correction to the initial water-cement ratio. The water-cement ratio of the fresh concrete sample after the second correction is calculated according to formula (3) and denoted as w / b2.

[0043]

[0044] The water content (m1-m2) in the fresh concrete sample obtained in step (5) above includes admixtures, that is, the water-cement ratio after the first correction is slightly greater than the actual water-cement ratio, and the initial water-cement ratio needs to be corrected again.

[0045] It should be noted that this invention employs a slurry-aggregate process to separate the freshly mixed concrete after drying, obtaining the actual mass of each component. By correcting the initial water-cement ratio twice, errors caused by the content of coarse and fine aggregates, admixture dosage, and solids content in the admixtures are eliminated in the calculation of the water-cement ratio of the freshly mixed concrete. This method can accurately determine the real-time water-cement ratio of the freshly mixed concrete, is simple to operate, and provides a guarantee for improving concrete quality control during construction.

[0046] In conjunction with the first aspect, in some embodiments of the present invention, in step (1), sampling of fresh concrete refers to taking a representative sample during the pouring process. The mass m1 can be in the range of 1kg-2kg. By controlling the sample quantity, the balance between detection efficiency and accuracy is ensured.

[0047] The sampling amount of 1kg-2kg refers to the range of concrete sample mass controlled quantitatively. This can be achieved using an electronic balance to ensure the sample mass falls within this range. This mass range is set based on a balance between the need for uniform aggregate distribution during actual testing and ease of operation. It avoids calculation errors caused by uneven aggregate distribution due to excessively small samples, while also preventing the increased time required for separation and drying steps due to excessively large samples.

[0048] Specifically, when the sample size is controlled between 1kg and 2kg, the ratio of aggregate to paste can reflect the overall mix proportions of the concrete. Simultaneously, the aggregate distribution density on the screen during sieving is moderate, facilitating washing and separation. For example, in a 1kg sample, the total mass ratio of coarse to fine aggregate is close to the actual concrete mix proportions, reducing weighing deviations caused by localized aggregate enrichment. Furthermore, this mass range allows for controllable drying time; for instance, at 100℃-110℃, the sample can reach constant weight within a reasonable time, avoiding decreased drying efficiency due to excessively large samples.

[0049] Compared to existing technologies, traditional testing methods typically do not explicitly define the sampling size. This can lead to situations where excessively large samples are selected in pursuit of accuracy, increasing the time required for steps such as sieving and drying. Alternatively, excessively small samples may be selected to shorten the testing cycle, but this can easily affect the accuracy of water-cement ratio calculations due to uneven aggregate distribution or amplified weighing errors. This invention resolves the contradiction between testing efficiency and accuracy by limiting the sampling range to 1kg-2kg.

[0050] Through the above technical solution, this invention significantly shortens the testing cycle while ensuring the accuracy of the water-cement ratio calculation. For example, in a 1kg sample, the aggregate washing and separation time can be controlled within 10 minutes, while the drying time for a 2kg sample is reduced by approximately 30% compared to a larger sample volume. This solution also reduces systematic errors caused by sample quality fluctuations; for example, the impact of weighing errors on the fine aggregate mass m is limited to an acceptable range, thereby ensuring the reliability of the water-cement ratio correction formula.

[0051] In conjunction with the first aspect, in some embodiments of the present invention, in step (2), the drying temperature is 100℃-110℃. This allows for rapid evaporation of free water without damaging the structure of the cementitious material.

[0052] Drying treatment refers to removing moisture from freshly mixed concrete samples through heating. Specifically, a drying oven can be used for constant-temperature heating, with precise temperature regulation achieved through temperature sensors and controllers. The lower limit of this temperature range is set at 100℃ to ensure the minimum thermodynamic conditions required for sufficient moisture evaporation; the upper limit is set at 110℃ to prevent dehydration and decomposition of cementitious materials or damage to the physical properties of aggregates due to high temperatures.

[0053] Specifically, by controlling the drying temperature within the range of 100℃ to 110℃, the evaporation requirements of both free and bound water are met, while preventing chemical structural changes in the hydration products within the cementitious material due to excessively high temperatures. For example, temperatures below 100℃ may result in residual moisture, affecting subsequent aggregate quality measurements; while temperatures above 110℃ may cause irreversible decomposition of cement hydration products, leading to cementitious material degradation. This temperature range strikes a balance between evaporation efficiency and material stability, ensuring accurate and reliable quality data for the dried samples and providing a basis for calculating the water-cement ratio.

[0054] Compared to existing technologies, traditional methods may use drying temperatures in a range that is either too high or too low. For example, using temperatures above 120°C to accelerate drying can lead to dehydration and carbonization of the cementitious material, while using temperatures below 80°C can result in incomplete moisture evaporation. This solution overcomes the problems of material deformation or measurement errors caused by improper temperature control in existing technologies by limiting the temperature range, thus maintaining the original state of the material while ensuring drying efficiency.

[0055] Through the above technical solution, the present invention achieves complete removal of moisture from fresh concrete samples, avoids chemical changes in cementitious materials due to high temperature, and ensures the integrity of the physical structure of aggregates, thereby improving the accuracy of water-cement ratio detection.

[0056] In conjunction with the first aspect, in some embodiments of the present invention, in step (3), the slurry-aggregate separation employs a nested system of 9.50mm, 4.75mm, and 0.075mm three-stage screens to achieve efficient separation of coarse aggregate, auxiliary sorting, and fine aggregate through step-by-step interception. Low-pressure water flow is used for water flushing, which can both wash away the adhering slurry and prevent aggregate breakage. The mud powder content parameter in the secondary correction is derived from the incoming inspection report, ensuring the authority of the correction data.

[0057] A screen refers to a multi-layer filtration device used in the pulp-aggregate separation process. For example, it may consist of a square-hole screen with apertures of 9.50 mm, 4.75 mm, and 0.075 mm, and its function is to classify aggregate particle size. By retaining the screen as an aggregate carrier, there is no need to transfer the aggregate to other containers, thus avoiding material loss during the transfer process.

[0058] The drying oven refers to equipment used for drying processes, with a temperature control range of, for example, 100℃-110℃, to remove moisture adsorbed on the surface of the aggregate through constant-temperature heating. The method of placing the screen and aggregate together in the drying oven eliminates the problem of aggregate residue that may occur in traditional transfer steps.

[0059] Specifically, after the pulp and aggregate separation is completed, the washed aggregate adheres to the screen surface. At this point, the screen and aggregate are directly transferred together to the drying oven for drying. During this process, the aggregate does not need to be poured from the screen into other containers, avoiding particle scattering or residue on the container walls caused by multiple transfers. For example, when drying coarse aggregate, the aggregate in the 9.50mm and 4.75mm screens enters the drying oven along with the screens, while the fine aggregate remains on the 0.075mm screen for simultaneous drying. After drying, the aggregate still adheres to the screen surface, and its mass can be concentrated in the weighing area by vibrating the screen for measurement.

[0060] Compared to existing technologies, traditional methods typically require transferring the separated aggregate to trays or dedicated containers for drying. This process can lead to aggregate particles scattering or adhering to the container's inner walls. For example, when coarse aggregate is transferred from a screen to a tray, some particles may remain in the screen gaps due to electrostatic adsorption or mechanical vibration, resulting in lower weighing results. This solution, however, eliminates the transfer step entirely by retaining the screen as the drying carrier, thus avoiding the risk of material loss at its source.

[0061] Through the above technical solution, the present invention effectively solves the measurement error problem caused by residue or scattering of aggregates during the transfer process, ensuring the accuracy of the total aggregate mass data. For example, when fine aggregates tend to adhere to the screen surface after rinsing, direct drying avoids the risk of fine particles falling off during transfer, thus making the subsequently calculated water-cement ratio correction value closer to the actual working conditions and improving the reliability of the test results.

[0062] In conjunction with the first aspect, in some embodiments of the present invention, in step (4), the sieve containing the aggregate is placed together with the aggregate into an oven for drying.

[0063] In conjunction with the first aspect, in some embodiments of the present invention, in step (5), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is less than 5%, and no admixture is used or the admixture dosage is less than 0.5%, the initial water-cement ratio specified in step (5) is the actual value of the water-cement ratio of the sample.

[0064] In this scheme, a mud and powder content below a certain threshold means that the mass percentage of impurities such as clay and dust in the aggregate is below a negligible range. This can be obtained from the mud and powder content test data in the aggregate arrival inspection report. In this approach, a low mud and powder content means that it has minimal interference with aggregate quality calculations, and no correction is needed to eliminate the error.

[0065] Among these, an admixture dosage below another threshold means that the admixture dosage does not reach a level that significantly affects the total amount of cementitious materials. This can be specifically obtained through the admixture dosage parameters in the concrete mix design document. In this scheme, the impact of admixtures on the amount of cementitious materials under low dosage conditions is negligible, therefore there is no need to compensate for its solids content by correction.

[0066] Specifically, when the aggregate mud powder content is below a certain threshold (e.g., 5%) and the admixture dosage is below another threshold (e.g., 0.5% of the total cementitious material), the moisture error introduced by aggregate impurities and the impact of admixture solids content on the total cementitious material are both within acceptable ranges. At this point, the initial water-cement ratio calculated based on the relationship between the dried aggregate mass and the total mass has sufficient accuracy and can be directly used as the actual value. By presetting the above conditions, subsequent correction steps are omitted in low-interference scenarios, reducing the computational complexity in the testing process and avoiding the risk of error accumulation due to redundant corrections.

[0067] Compared to existing technologies, traditional methods typically require multiple forced corrections to the water-cement ratio, regardless of whether the aggregate powder content or admixture dosage is at a low level. For example, some testing procedures require a complete correction process for all samples, including powder content compensation and admixture solids adjustment. This solution, however, sets thresholds for powder content and admixture dosage, triggering corrections only when these thresholds are exceeded. Under low-interference conditions, the initial calculation results are directly used, effectively reducing unnecessary operational steps.

[0068] Through the above technical solution, this invention solves the problem of redundancy in the water-cement ratio detection process under conditions of low mud powder content and low admixture dosage, thereby improving detection efficiency. Specifically, when the influence of aggregate impurities and admixtures is small, two correction calculations are directly omitted, reducing the detection steps from seven to five. At the same time, it avoids operational errors that may occur during the acquisition and calculation of correction parameters, shortening the detection time while ensuring the reliability of the results.

[0069] In conjunction with the first aspect, in some embodiments of the present invention, in step (6), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is greater than 5%, and no admixture is used or the admixture dosage is less than 0.5%, the first corrected water-cement ratio specified in step (6) is the actual value of the water-cement ratio of the sample.

[0070] The clay and dust content of coarse and fine aggregates refers to the percentage of clay or dust adhering to the aggregate surface to the total aggregate mass. This can be calculated using the drying and weighing method or data from the incoming inspection report. This parameter directly affects the effective mass of the aggregate and the actual proportion of cementitious materials, and its influence on the water-cement ratio calculation needs to be corrected.

[0071] The admixture dosage refers to the percentage of the admixture added relative to the total mass of the cementitious material, which can be obtained from the mix proportion data or the factory test report. When the dosage is below the critical value, its effect on adjusting the water-cement ratio is negligible, and no secondary correction is required.

[0072] Specifically, when the mud powder content in coarse and fine aggregates exceeds a set threshold, the mud powder coating the aggregate surface absorbs some of the mixing water, causing the initial water-cement ratio calculation to deviate from the true value. When admixtures are not used or their dosage is too low, their water-retaining and thickening effects cannot effectively regulate the fluidity of the slurry. In this case, adding a secondary correction may introduce calculation bias. By establishing a correlation judgment rule between mud powder content and admixture dosage, when mud powder interference is significant but the admixture effect does not meet the correction requirements, the initial water-cement ratio corrected for aggregate quality is directly adopted. This avoids the accumulation of errors caused by over-correction and simplifies the testing steps.

[0073] Compared to existing technologies, traditional water-cement ratio testing methods typically ignore the interaction of material parameters and apply independent corrections for mud powder content and admixture dosage, which can easily lead to overcorrection errors under low admixture conditions. This proposed solution establishes a selective correction mechanism by setting correlation thresholds for material parameters, effectively balancing the trade-off between testing accuracy and operational complexity.

[0074] Through the above technical solution, this invention can accurately identify testing scenarios that do not require secondary correction under conditions where high mud powder content and low admixture dosage coexist, avoiding error propagation caused by invalid calculation steps. Simultaneously, by simplifying the correction process, it shortens the testing time, ensuring that reliable water-cement ratio test results are obtained quickly before the initial setting of concrete.

[0075] In conjunction with the first aspect, in some embodiments of the present invention, in step (6), the content of coarse aggregate mud powder α and the content of fine aggregate mud powder β can be obtained from the coarse and fine aggregate incoming inspection report.

[0076] The coarse aggregate mud content α refers to the mass percentage of mud powder adhering to or embedded in the surface of particles larger than 4.75mm in the aggregate. This can be calculated from the mud content test data conducted upon arrival of the coarse and fine aggregates according to specifications. This parameter reflects the amount of impurities introduced into the aggregate during transportation and storage. The fine aggregate mud content β refers to the mass percentage of particles smaller than 0.075mm in sand with a particle size smaller than 4.75mm. This can be directly obtained from the mud content test results conducted upon arrival according to standards. This parameter quantifies the cleanliness of the fine aggregate. Using on-site test data ensures that the parameter sources meet the requirements of the engineering quality management system and avoids deviations caused by uneven on-site sampling or differences in testing conditions.

[0077] Specifically, the incoming inspection reports for coarse and fine aggregates serve as original quality certificates jointly confirmed by the material supplier and the construction party. The data is obtained by a qualified testing institution according to national standard test methods. For example, upon arrival, coarse aggregates are tested for mud content according to GB / T 14685, and the α value is determined using the water washing sieve method; fine aggregates are tested for mud content according to GB / T 14684, and the β value is determined using the standard sieve analysis method. Directly incorporating the aforementioned archived test data into the water-cement ratio correction formula eliminates operational errors caused by repeated on-site testing and avoids measurement distortions caused by secondary contamination during aggregate storage. Since the incoming inspection data has legal validity and has been confirmed by multiple parties, its use as a source of correction parameters effectively ensures the traceability of the water-cement ratio calculation.

[0078] Compared to existing technologies, traditional methods often require secondary sampling and testing of aggregates at the construction site. This not only necessitates specialized testing equipment but can also lead to measurement errors due to sampling location deviations or inconsistent operating techniques. For example, when using rapid sieving to determine mud powder content on-site, the test results for the same batch of aggregates may fluctuate by ±0.5% due to factors such as environmental humidity and equipment accuracy. This solution, however, directly utilizes completed incoming inspection data, eliminating the need for repeated testing and ensuring the standardization and consistency of the data source.

[0079] Through the above technical solution, the present invention solves the problem of accuracy and reliability in obtaining water-cement ratio correction parameters, avoids human error by standardizing data sources, and shortens the correction process time by about 30%, so that the water-cement ratio detection process can match the pouring rhythm of the construction site, and realizes the coordinated optimization of quality control and project progress.

[0080] In conjunction with the first aspect, in some embodiments of the present invention, in step (7), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is greater than 5% and the admixture dosage is higher than 0.5%, the second corrected water-cement ratio specified in step (7) is the actual value of the water-cement ratio of the sample.

[0081] The present invention further proposes that when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is greater than a set threshold, and the admixture dosage is higher than a set threshold, the water-cement ratio after the second correction is the actual value of the water-cement ratio of the sample.

[0082] The coarse and fine aggregate mud powder content refers to the percentage of fine particulate matter adhering to or mixed with the aggregate surface to the total mass of the aggregate. Specifically, it can be obtained using the measured data provided in the aggregate arrival inspection report as an input parameter. In the calculation process, it is used to quantify the interference error of impurities on the total amount of cementitious materials. The admixture dosage refers to the percentage of admixture to the total mass of cementitious materials. Specifically, it can be obtained using the dosage ratio indicated in the admixture factory inspection report. This parameter is used to measure the supplementary effect of the solid components of the admixture on the total amount of cementitious materials. The solids content refers to the mass percentage of solid matter in the admixture solution. Specifically, it can be obtained through a drying method test. This parameter is used to correct for the influence of additional solid matter introduced by the admixture on the water-cement ratio calculation.

[0083] Specifically, when the aggregate mud powder content exceeds a set threshold and the admixture dosage is in a high range, it indicates that the moisture adsorbed by aggregate impurities and the solid components of the admixture both contribute significantly to the total amount of cementitious material. In this case, a step-by-step correction method is used. First, the initial water-cement ratio is corrected based on the mud powder content parameter to eliminate the quality error of the cementitious material caused by impurities. Then, the admixture dosage and solids content parameters are introduced for a second correction, incorporating the effective solid components of the admixture into the total amount of cementitious material. This step-by-step approach avoids the formula coupling problem caused by simultaneous correction of multiple parameters, and eliminates error interference from different sources through two independent corrections.

[0084] Compared with existing technologies, traditional methods only address the single factor of mud powder content or admixtures through a single correction, failing to solve the complex error problem when high mud powder and high admixture levels coexist. This solution establishes a graded correction model, which, while maintaining the simplicity of the calculation process, achieves independent quantification of the influence of aggregate impurities and admixture parameters on the water-cement ratio, overcoming the measurement inaccuracies caused by the superposition of errors in existing technologies.

[0085] Through the above technical solution, the present invention can accurately eliminate the calculation deviation of the total amount of cementitious materials caused by high mud powder content, and simultaneously correct the supplementary effect of admixture solid content on the total amount of cementitious materials, so that the corrected water-cement ratio truly reflects the mass ratio of actual water and effective cementitious materials in concrete, providing reliable test data for complex working conditions with excessive aggregate impurities and high admixture dosage.

[0086] In conjunction with the first aspect, in some embodiments of the present invention, in step (7), the admixture dosage γ and the admixture solid content ω can be obtained from the admixture factory inspection report.

[0087] The admixture dosage γ refers to the proportion of admixture added to concrete, which can be determined by the mass percentage of admixture to cementitious materials in the mix design produced by the mixing plant. This proportion has been determined through standardized testing during factory inspection. The solids content ω refers to the mass percentage of solid components in the admixture solution, which can be determined by testing the ratio of the total mass of the admixture solution to the mass of solid residue using the drying method. The test data is provided by the admixture manufacturer in the factory inspection report. By directly referencing the parameters in the factory inspection report, parameter deviations caused by human error or insufficient instrument precision during on-site operation can be avoided.

[0088] Specifically, the batches of admixtures used in concrete production at the batching plant are consistent with the batches corresponding to the factory inspection reports. The data in the factory inspection reports have undergone standardized laboratory testing, ensuring traceability and authority. In the second correction calculation, the admixture dosage γ is used to adjust the calculated effective content of cementitious materials, and the solids content ω is used to correct the impact of ineffective water introduced by the admixtures on the total water consumption. Since the storage conditions of admixtures may cause changes in the solution state, directly using the factory inspection data can eliminate interference from transportation or storage processes on the stability of admixture parameters.

[0089] In some specific implementations, the admixture factory test report may contain dosage and solids content data for multiple batches. For example, when the same type of admixture is supplied in batches, each batch corresponds to an independent test report number. During the production process, the parameter values ​​of the corresponding batch are retrieved based on the admixture usage records to ensure that the input data during correction calculations completely matches the actual batches used.

[0090] Compared to existing technologies, traditional methods typically rely on on-site sampling to test admixture parameters. However, changes in ambient temperature and humidity can affect the accuracy of test results. For example, testing the solid content of a solution requires precise control of drying temperature and time, which is quite challenging. Using factory test report data reduces on-site testing procedures and avoids the risk of data distortion due to improper operation or equipment errors.

[0091] Through the above technical solution, the present invention can ensure the reliability of the source of admixture parameters and the consistency of data in the second correction calculation of water-cement ratio, avoid the correction result from deviating from the true value due to inaccurate parameter acquisition, thereby improving the overall accuracy and engineering applicability of water-cement ratio test results.

[0092] Specifically, after the test samples underwent two drying treatments to eliminate moisture interference, aggregates of different particle sizes were precisely separated using a three-stage sieve. The mass of coarse and fine aggregates was measured separately, and the initial water-cement ratio was calculated based on the total amount of cementitious materials. An initial correction compensated for mass errors caused by surface deposits on the aggregates using the mud powder content parameter. A second correction adjusted the water content calculation based on the actual composition of the admixtures, ultimately yielding a water-cement ratio value that reflects the actual working conditions. A reverse washing method was used during the aggregate separation stage, and fine aggregates were immediately subjected to anti-scattering treatment after collection to ensure weighing accuracy.

[0093] Compared to existing technologies, traditional methods often employ chemical dissolution to separate the slurry, generating waste liquid and damaging the sample during the testing process. This proposed method achieves non-destructive testing through physical sieving, preserving the complete morphology of the aggregate. Existing technologies only consider a single correction factor, while this method innovatively establishes a dual composite correction model, simultaneously covering fluctuations in raw material quality and the influence of additives. Traditional water-cement ratio testing requires back-calculation after concrete hardening, while this method can complete the entire testing process on-site within 30 minutes.

[0094] Through the above technical solutions, this invention can monitor fluctuations in the water-cement ratio of fresh concrete in real time and provide timely warnings of exceeding the standard. The test data can guide on-site adjustments to water usage, avoiding problems such as decreased structural strength and deteriorated impermeability caused by deviations in the water-cement ratio. The correction model effectively eliminates interference from aggregate mud content and admixtures, improving the testing accuracy to within the engineering control requirements. The combination of grading and screening with double drying ensures the accuracy of aggregate quality measurement, establishing a reliable data foundation for water-cement ratio calculation.

[0095] In conjunction with the first aspect, in some embodiments of the present invention, the units of m1, m2, m3, M, and m are accurate to 1g.

[0096] The sampling mass of fresh concrete refers to the initial mass of the sample to be tested taken from the concrete being poured. Specifically, it can be weighed using an electronic balance, with the reading accuracy adjusted to 1 gram to eliminate the mass reference error during the sampling stage.

[0097] The total mass of the dried slurry and aggregate refers to the total mass of the sample after dehydration. Specifically, it can be obtained by using a weighing device accurate to 1 gram after drying in an oven, thus avoiding errors in the calculation of residual moisture.

[0098] The total mass of aggregates refers to the total mass of coarse and fine aggregates after washing and separation and secondary drying. This can be achieved by weighing the aggregates on each screen step by step and adding them up, ensuring the accuracy of the aggregate ratio calculation.

[0099] Among them, the mass of coarse aggregate refers to the mass of aggregate retained by 9.50 mm and 4.75 mm sieves, and the mass of fine aggregate refers to the mass of aggregate retained by 0.075 mm sieve. Specifically, the aggregate can be collected in stages and weighed independently to make the calculation basis of the mud powder content correction parameter more reliable.

[0100] Specifically, by standardizing the measurement accuracy of quality parameters at each stage to 1 gram, the propagation magnitude of errors in the calculation chain can be effectively controlled. In the initial sampling stage, weighing with an accuracy of 1 gram can reduce the systematic deviation of the baseline value in the subsequent water-cement ratio calculation; in the total mass determination after drying, accuracy to 1 gram can reduce the impact of moisture evaporation estimation errors on the amount of cementitious materials used; in the aggregate separation stage, accurate measurement of the mass of coarse and fine aggregates can accurately reflect the original data required for the correction of mud powder content; finally, in the two water-cement ratio correction calculations, the cumulative error of each quality parameter is limited to a controllable range, thereby ensuring the reliability of the correction results.

[0101] Compared to existing technologies, conventional methods for testing the water-cement ratio of concrete typically use units of measurement accurate to 5 or 10 grams, leading to amplified errors in multiple calculations. For example, a 5-gram deviation in the mass of the coarse aggregate after separation directly affects the accuracy of the correction factor for the mud powder content, thus causing the final water-cement ratio to deviate from the true value. However, using a measurement method with a 1-gram accuracy can reduce the error of a single measurement to one-fifth to one-tenth of the original level, significantly suppressing the error propagation effect.

[0102] Through the above technical solution, this invention solves the problem of distorted water-cement ratio calculation results caused by insufficient precision of mass units. By strictly controlling the measurement accuracy of mass parameters at each stage, the calculation basis for the mud powder content correction coefficient and solids content correction value is made more accurate, thereby improving the reliability of the two water-cement ratio corrections and ensuring that the actual water-cement ratio test results truly reflect the construction quality of fresh concrete.

[0103] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0104] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0106] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0107] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0108] To further verify the feasibility of the rapid detection method for water content fluctuation in freshly mixed concrete, rapid detection was performed on the following three groups of samples.

[0109] The raw materials used are as follows:

[0110] Cement: 42.5 ordinary Portland cement;

[0111] Fine aggregates: washed sand and manufactured sand, wherein the manufactured sand contains 10% stone powder;

[0112] Coarse aggregate: divided into washed crushed stone and ordinary crushed stone, of which the mud powder content of ordinary crushed stone is 2%;

[0113] Water-reducing agent: Polycarboxylate high-performance water-reducing agent with a solid content of 20% is selected;

[0114] Water: laboratory water, with water-cement ratios of 0.4, 0.4 and 0.3 for samples 1 to 3, respectively.

[0115] Table 1 Concrete mix proportions (kg / m³) 3

[0116] Group cement Washed sand Manufactured sand Washed gravel ordinary crushed stone water Water reducing agent Sample 1 450 630 1190 180 Sample 2 450 570 1190 180 Sample 3 450 570 1190 135 2％

[0117] A total of 0.01m³ of concrete was prepared in the laboratory according to the above concrete mix proportions. 3 Take 2 kg of samples and label them as sample 1, sample 2 and sample 3 respectively. Obtain each sample m1, m2 and m3 according to steps (1)-(4) respectively, and calculate w / b, w / b1 and w / b2.

[0118] Table 2 Calculation Results

[0119] Group <![CDATA[m1 / g]]> <![CDATA[m2 / g]]> M / g m / g <![CDATA[m3 / g]]> w / b w / b1 w / b2 relative error Time Sample 1 2005 1856 518 971 1489 0.406 - - 1.50％ 25min Sample 2 2001 1851 489 928 1417 0.346 0.409 - 2.25％ 25min Sample 3 1997 1883 498 948 1446 0.261 0.309 0.295 1.66％ 25min

[0120] The calculation process is shown in Table 2. The results show that this method can quickly identify the water content of fresh concrete, and the calculation results are close to the actual water-cement ratio (0.4, 0.4, and 0.3, respectively), which can provide a reference for the fluctuation of water content in fresh concrete during on-site construction.

[0121] It should be noted that samples 1, 2 and 3 are representative, representing the ideal concrete mix proportion without silt powder, the ordinary concrete mix proportion with common aggregates (containing silt powder), and the concrete mix proportion with common water-reducing agents, respectively. Stone powder or silt will cause errors in this method, so some calculations are needed to correct them.

[0122] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A rapid detection method for water content fluctuation in freshly mixed concrete, characterized in that, Includes the following steps: (1) Sampling of fresh concrete: Take a section of fresh concrete with a mass of m1 that is being poured as the sample to be tested; (2) Weighing after drying: The sample to be tested is dried until constant weight, then cooled to room temperature, and the mass of the dried sample to be tested is weighed and recorded as m2. (3) Slurry-aggregate separation: Square hole sieves with diameters of 9.50 mm, 4.75 mm and 0.075 mm are used to separate slurry and aggregate in sequence: The sample to be tested with a mass of m2 is poured into the three nested sieves and rinsed with water. After rinsing, the aggregate filtered from each sieve is collected. (4) Drying aggregates: Dry the collected aggregates again to constant weight, and after cooling to room temperature, weigh the coarse aggregates in the 9.50 mm square hole sieve and the 4.75 mm square hole sieve, and record the mass as M; weigh the fine aggregates in the 0.075 mm square hole sieve, and record the mass as m; record the total mass of coarse and fine aggregates as m3. (5) Calculate the water-cement ratio: Calculate the initial water-cement ratio of the freshly mixed concrete sample according to formula (1), and record it as w / b; (6) First correction of water-cement ratio: Two parameters, coarse aggregate mud powder content α and fine aggregate mud powder content β, are introduced to make the first correction of the initial water-cement ratio. The water-cement ratio of the fresh concrete sample after the first correction is calculated according to formula (2) and denoted as w / b1. (7) Second correction of water-cement ratio: Two parameters, admixture dosage γ and admixture solid content ω, are introduced to correct the initial water-cement ratio for the second time. The water-cement ratio of the fresh concrete sample after the second correction is calculated according to formula (3) and denoted as w / b2.

2. The rapid detection method according to claim 1, characterized in that, In step (1), m1 is 1kg-2kg.

3. The rapid detection method according to claim 1, characterized in that, In step (2), the drying temperature is 100℃-110℃.

4. The rapid detection method according to claim 1, characterized in that, In step (4), the sieve containing the aggregate is placed into the drying oven along with the aggregate for drying.

5. The rapid detection method according to claim 1, characterized in that, In step (5), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is less than 5%, and no admixtures are used or the admixture dosage is less than 0.5%, the initial water-cement ratio specified in step (5) is the actual value of the water-cement ratio of the sample.

6. The rapid detection method according to claim 1, characterized in that, In step (6), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is greater than 5%, and no admixtures are used or the admixture dosage is less than 0.5%, the first corrected water-cement ratio specified in step (6) is the actual value of the water-cement ratio of the sample.

7. The rapid detection method according to claim 1, characterized in that, In step (6), the content of coarse aggregate mud powder α and the content of fine aggregate mud powder β can be obtained from the coarse and fine aggregate incoming inspection report.

8. The rapid detection method according to claim 1, characterized in that, In step (7), when the mud powder content of coarse and fine aggregates in the raw materials used in fresh concrete is greater than 5% and the admixture dosage is higher than 0.5%, the water-cement ratio specified in step (7) after the second correction is the actual value of the water-cement ratio of the sample.

9. The rapid detection method according to claim 1, characterized in that, In step (7), the admixture dosage γ and the admixture solid content ω can be obtained from the admixture factory inspection report.

10. The rapid detection method according to any one of claims 1 to 9, characterized in that, The units of m1, m2, m3, M, and m are accurate to 1g.

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