Method and system for detecting and controlling concrete workability in mixer truck

Abstract

The present invention belongs to the technical field of detection and regulation of workability of fresh concrete, and discloses a method and system for detection and regulation of workability of concrete in a mixer truck, including installing a rheological shearing device and a temperature testing device in the drum of the mixer truck, and utilizing the rotation of the drum to drive the shearing rod to shear in the concrete, so as to directly test the rheological properties of the concrete, and obtain the working performance through the relationship between the rheological properties and the workability. The test starts before the concrete mixer truck leaves the factory, and the rheological properties of the concrete are continuously measured during transportation, and the degree of change and trend thereof are evaluated, and the evaluation results are compared with the pre-set limit values. When the limit values ​​are reached or exceeded, an alarm is immediately sounded and the supplementary admixture regulation is automatically implemented, so that the rheological properties of the concrete can be kept within the required set range through real-time continuous monitoring, fine-tuning, and pre-adjustment during the entire transportation. The present invention can realize the directness, real-timeness and accurate regulation of the workability detection of concrete during transportation.

Description

Technical Field

[0001] The present invention belongs to the technical field of detection and regulation of workability of fresh concrete, and more specifically, relates to a method and system for detection and regulation of workability of concrete in a mixer truck. Background Art

[0002] At present, the quality control of ready-mixed concrete is mainly in the production and factory inspection links. During the period from transportation to delivery to the construction site, the performance changes of concrete in the mixer truck (mixing tank truck) are out of control. The on-board transportation time (from factory to delivery) is affected by the distance of transportation, traffic congestion, sudden traffic accidents, and unpredictable waiting time before delivery. The cement in the concrete will begin to hydrate after contacting with water, resulting in a continuous decrease in the water content of the concrete and a continuous change in the workability of the concrete. The workability of the ready-mixed concrete at the time of leaving the factory changes unpredictably during transportation due to the aforementioned uncontrollable factors. When it is delivered to the construction site, once the workability of the concrete deviates from the expected control range, it will not meet the construction requirements, which will lead to the abandonment of the concrete or affect the quality and safety of the concrete project. Therefore, it is of great significance to detect and control the workability of concrete under the dynamic transportation.

[0003] In the prior art, there is a method for testing the workability of concrete under dynamic transportation. The method discloses a time-varying test method for the workability of concrete based on tank strain. The method reflects the workability of concrete by collecting stress-strain data of the tank wall. However, the pipe wall of the mixer truck has a certain thickness. The stress-strain data of the tank wall is used to indirectly reflect the workability of concrete, resulting in low detection accuracy of the workability of concrete and poor real-time performance. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a method and system for detecting and controlling the workability of concrete in a mixer truck, which aims to improve the accuracy and real-time performance of concrete workability detection.

[0005] To achieve the above object, according to a first aspect of the present invention, a method for detecting the workability of concrete in a mixer truck is provided, comprising:

[0006] A rheological shear device placed in the drum of a mixer truck is used to directly convert the resistance of concrete flowing at different moments during the rotation of the drum into a pressure signal; wherein the rheological shear device includes the rheological shear rod and a pressure sensor; the rheological shear rod extends into the concrete in the drum, and is used to directly detect the resistance of concrete during shear flow during the rotation of the drum, and the resistance is converted into the pressure of the pressure sensor through the lever principle;

[0007] Based on the pressure signal, the relationship between the cylinder rotation speed and the resistance of the rheological shear rod at different times is obtained; the straight line intercept of the relationship represents the yield value, and the straight line slope of the relationship represents the plastic viscosity;

[0008] The yield value and the plastic viscosity are used to reflect the workability, and the time-varying relationship of the workability during concrete transportation is obtained, thereby achieving real-time detection of the workability.

[0009] Furthermore, it also includes: real-time measurement of the temperature T of concrete during transportation to establish the relationship between the yield value, the plastic viscosity, the apparent viscosity and the temperature T over time; wherein the temperature T includes the temperature of the concrete in the drum of the mixer truck, and / or the temperature T also includes the ambient temperature inside and outside the drum of the mixer truck to obtain the temperature difference between the internal and external environments of the drum of the mixer truck.

[0010] According to a second aspect of the present invention, there is provided a method for regulating the workability of concrete in a mixer truck, comprising: pre-establishing a database of time-varying relationships of apparent viscosity of concrete of different categories, strength grades and workability requirements under different transportation conditions;

[0011] The concrete workability detection method in the mixer truck described in the first aspect is used to detect the workability of the concrete at different times during transportation in real time until it arrives at the delivery location;

[0012] During transportation, at regular intervals, the corresponding apparent viscosity is calculated based on the yield value and plastic viscosity detected in real time; and the apparent viscosity is compared with the corresponding apparent viscosity in the database to obtain the trend of the apparent viscosity difference over time during the period;

[0013] During this period, the trend of the apparent viscosity difference changing with time causes the workability to deteriorate, and when it reaches the preset warning value, the admixture is automatically added to adjust the workability of the concrete in real time.

[0014] Furthermore, during this period of time, the workability reflected by some of the apparent viscosity differences deteriorates, and the workability control method further includes:

[0015] Based on the apparent viscosity difference of this part, as well as the yield value and plastic viscosity corresponding to the apparent viscosity difference of this part and the pressure data measured by the pressure sensor, an optimization algorithm is used to decide whether automatic supplementation of additives is required.

[0016] Furthermore, the type of admixture, the amount of each addition and the number of additions are automatically optimized and decided using an optimization algorithm according to the concrete workability target set at the time of delivery.

[0017] Furthermore, it also includes real-time monitoring of the time of the concrete mixer truck in transit, the actual route, and the unloading delivery location and time to assist in the regulation of concrete workability.

[0018] According to a third aspect of the present invention, there is provided a concrete workability detection system in a mixer truck, comprising:

[0019] The rheological shear device placed in the drum of the mixer truck is used to directly convert the resistance of the rheological shear rod when the concrete flows at different times during the rotation of the drum into a pressure signal; wherein the rheological shear device includes the rheological shear rod and a pressure sensor; the rheological shear rod extends into the concrete in the drum, and is used to directly detect the resistance of the concrete during shear flow during the rotation of the drum, and the resistance is converted into the pressure of the pressure sensor through the lever principle;

[0020] A rheological parameter calculation module, for obtaining the relationship between the cylinder rotation speed and the resistance of the rheological shear rod at different times based on the pressure signal; the straight line intercept of the relationship represents the yield value, and the straight line slope of the relationship represents the plastic viscosity;

[0021] The workability real-time detection module is used to reflect the workability by using the yield value and the plastic viscosity, obtain the time-varying relationship of the workability during concrete transportation, and realize the real-time detection of the workability.

[0022] Further, a temperature sensor is included;

[0023] The temperature sensor is used to measure the temperature T of concrete in real time during transportation, so as to establish the relationship between the yield value, the plastic viscosity, the apparent viscosity and the temperature T changing with time; wherein the temperature T includes the temperature of the concrete in the drum of the mixer truck, and / or the temperature T also includes the temperature of the internal and external environments of the drum of the mixer truck to obtain the temperature difference between the internal and external environments of the drum of the mixer truck.

[0024] Furthermore, the rheological shear rod is in the shape of a sheet rod, and the length and cross-sectional shape of the sheet rod are adjusted according to the resistance encountered by different concretes during the shear flow.

[0025] According to a fourth aspect of the present invention, there is provided a concrete workability control system in a mixer truck, comprising:

[0026] A database construction module is used to pre-establish a database of the time-varying relationship of the apparent viscosity of concrete of different categories, strength grades and workability requirements under different transportation conditions;

[0027] A workability detection system is used to detect the workability of concrete at different times during transportation in real time until it reaches the delivery location; wherein the workability detection system is the workability detection system during transportation of concrete described in the third aspect,

[0028] A calculation module is used to calculate the corresponding apparent viscosity based on the yield value and plastic viscosity detected in real time at regular intervals during transportation; and compare the apparent viscosity with the corresponding apparent viscosity in the database to obtain the trend of the apparent viscosity difference over time during the period;

[0029] The automatic replenishing and spraying admixture device is used to automatically replenish admixtures when the apparent viscosity difference changes with time during the period, causing the workability to deteriorate and reaching a preset warning value, so as to adjust the workability of the concrete in real time.

[0030] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0031] (1) The method for detecting the workability of concrete in a mixer truck described in the present invention directly converts the rheological shear resistance of concrete flowing on the rheological shear rod at different times during the rotation of the mixer truck drum into a pressure signal through a rheological shear device placed in the mixer truck drum. Based on the pressure signals corresponding to different times during the rotation of the mixer truck drum, the relationship between the rotation speed of the mixer truck drum and the resistance of the rheological shear rod can be obtained; the rheological shear rod extending into the concrete performs a rheological property test on the flowing concrete while rotating with the drum. Since the drum rotation speed is proportional to the shear rate, and the resistance of the rheological shear rod is proportional to the shear stress, the rheological properties of concrete generally show Bingham body behavior, that is, there is a linear relationship between the shear rate and the shear resistance. Therefore, the obtained relationship between the rotation speed of the mixer truck drum and the resistance of the rheological shear rod can characterize the relationship between the shear rate and the shear resistance of the concrete. The intercept corresponding to the relationship between the rotation speed of the mixer truck drum and the resistance of the rheological shear rod represents the yield value, and the slope of the straight line represents the plastic viscosity, which can reflect the apparent viscosity in the rheological sense, and further characterize the workability. The changes in yield value and plastic viscosity at different times during transportation can reflect the changes in concrete workability over time. In this way, the present invention realizes direct detection of the workability of fresh concrete in a mixer truck during transportation. The data collected during the detection process is direct test data of shear flow of concrete in the drum of a rotating mixer truck, which has the advantages of high accuracy, strong real-time performance and being independent of the drum shape of different transport vehicles.

[0032] (2) Furthermore, the present invention takes into account that the hydration of cement in concrete leads to a decrease in the amount of water in the concrete, an increase in the solid phase, and an increase in viscosity. The temperature increase caused by hydration leads to an acceleration of the hydration reaction, which also affects the change in the workability of the concrete over time. Therefore, the method of the present invention also includes real-time measurement of the temperature T during the transportation of the concrete to establish the relationship between the yield value, plastic viscosity and apparent viscosity and the change in temperature T over time, so as to further improve the accuracy of the prediction of the change in the workability of the freshly mixed concrete. Preferably, in addition to the temperature of the concrete in the drum of the mixer truck, the measured temperature also includes the temperature in the drum of the mixer truck and the ambient temperature outside the drum, thereby obtaining the difference between the temperature inside and outside the drum, so as to facilitate the construction of the corresponding relationship between the change in workability and temperature according to the actual climate environment, thereby facilitating the further improvement of the accuracy of the prediction of the trend of the change in the workability of the freshly mixed concrete and the accuracy of the pre-adjusted workability of the admixture.

[0033] (3) Preferably, the rheological shear rod is in the shape of a sheet rod, and its length and cross-sectional shape can be adjusted according to the shear flow resistance of different concretes, so that a relatively balanced and stable resistance value can be obtained, thereby further improving the accuracy of workability change detection.

[0034] (4) Further, based on the concrete workability detection method in the mixer truck provided by the present invention, a corresponding control method is also provided. According to the workability detected in real time during transportation, based on the standard value in the pre-constructed database and the relationship between the evolution of concrete rheology over time at a certain ambient temperature, if the rheological properties change in the direction of increasing viscosity over time over a period of time and exceed the preset warning value, the automatic addition of admixtures is triggered to control the workability of the concrete to ensure that the concrete workability meets the requirements. The present invention can more accurately control the change of concrete workability in transit, solve the problem of lack of quality monitoring and control during concrete transportation, and is conducive to further optimizing the design and adjustment of concrete mix proportions, avoiding blindly increasing the amount of admixtures, reducing the losses caused by abandonment due to non-compliance with workability, and improving the quality level of concrete engineering.

[0035] (5) Furthermore, with the support of the database, on the basis of the prediction of the change trend of the apparent viscosity difference, it is also possible to use an optimization algorithm based on the corresponding yield value and plastic viscosity to intelligently determine whether it is necessary to automatically add admixtures to adjust the yield value or plastic viscosity, more accurately add the type and quantity of admixtures, and the frequency of admixture addition, so as to better regulate the rheological properties and meet the workability requirements.

[0036] (6) Furthermore, it also includes real-time monitoring of the time, actual route, unloading and delivery location and time of the mixer truck during transportation, real-time grasp of unexpected timeouts that may occur during concrete transportation, and timely implementation of regulation and quality management.

[0037] In summary, the present invention realizes real-time monitoring of concrete workability in a mixer truck by real-time detection and regulation of workability, and can meet the requirements of owners, supervision units and relevant government agencies to remotely monitor the quality management of ready-mixed concrete terminal products online.

[0038] The method of the present invention can directly test and regulate the workability of concrete during transportation by a mixer truck. Based on the designed rheological shearing device installed in the drum of the mixer truck, relevant data of the mixing flow of concrete at different times during transportation can be directly collected, and the rheological properties, temperature properties and their evolution of the freshly mixed concrete in the mixing drum can be directly and continuously detected, its changes during transportation can be monitored, and intelligent regulation can be implemented to realize quality monitoring and guarantee of the concrete in the final transportation link. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of a method for detecting the workability of concrete in a mixer truck in an embodiment of the present invention.

[0040] Figure 2 Schematic diagram of the change of the rod torque over time in an embodiment of the present invention.

[0041] Figure 3 Schematic diagram of the relationship between the rod torque and rotation speed under different cement conditions in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0043] Example 1

[0044] like Figure 1 As shown, an embodiment of the present invention provides a method for detecting the workability of concrete in a mixer truck based on rheological properties testing, which mainly includes:

[0045] S1. A rheological shear device placed in the drum of a mixer truck is used to directly convert the resistance of concrete flow at different times during the rotation of the drum of the mixer truck into a pressure signal; wherein, the rheological shear device designed in the embodiment of the present invention includes a rheological shear rod and a pressure sensor designed by the lever principle, and the rheological shear rod extending into the concrete in the drum is directly subjected to the resistance of concrete flow during the rotation of the drum of the mixer truck, and the resistance is converted into the pressure of the pressure sensor through the lever principle; through the rheological shear device, the resistance of concrete flow at the drum rotation speed can be directly converted into the pressure of the pressure sensor in the drum through the fulcrum, and the pressure data is used to characterize the pressure generated by the concrete flow at different times during the rotation of the drum of the mixer truck during transportation. Preferably, the pressure sensor is arranged at the bottom of the drum and passes through the drum, and the connected rod is immersed in the concrete. Preferably, the rheological shear rod is a sheet rod, for example, a square rod, and its cross section is rectangular. The length and cross-sectional shape of the sheet rod are adjusted according to the resistance of different concrete shear flows, so that a more balanced resistance value can be obtained, and the workload detection accuracy can be further improved. In other embodiments, the rheological shearing rod may also be other rod-shaped shearing components, such as a round rod, an elliptical rod, etc. The designed rheological shearing device can be disassembled, cleaned, and the worn parts can be replaced. In the embodiment of the present invention, the rheological shearing device can also be installed in the middle of the drum of the rotary mixer truck and penetrate the drum.

[0046] S2. Based on the pressure signals corresponding to different moments during the rotation of the mixer truck drum, the relationship between the rotation speed of the mixer truck drum and the resistance of the rheological shear rod is obtained; wherein, the rheological shear rod extending into the concrete shears the concrete as it rotates with the drum, and different rotation speeds correspond to different shear resistances. In the rheological sense, the drum rotation speed is proportional to the shear rate, and the resistance of the rheological shear rod is proportional to the shear stress. Therefore, the relationship between the rotation speed of the mixer truck drum and the resistance of the rheological shear rod can characterize the relationship between the shear velocity and shear resistance of the concrete. There is a linear relationship between the shear velocity and the shear resistance. Therefore, the intercept corresponding to the relationship between the rotation speed of the mixer truck drum and the resistance of the rheological shear rod represents the structural strength (i.e., yield value) of the coarse suspension of the fresh concrete. An intercept of zero represents that the particles of the coarse suspension of the concrete are in a fully dispersed state, and the slope of the straight line represents the plastic viscosity. The yield value and plastic viscosity are used as rheological parameters to reflect the rheological properties of concrete. If the relationship between the drum speed of the mixer truck and the resistance of the rheological shear rod obtained over a period of time has deviated from the linear relationship, then to a certain extent, it can be judged that the rheological properties of the current concrete have changed significantly. The change in rheological properties over time is used to characterize the change in the workability of concrete over time. In the embodiment of the present invention, the workability includes slump, expansion, and the time from collapse to stability. The slump and expansion of concrete under deadweight mainly depend on the yield value of the ready-mixed concrete, and the time from collapse to stability mainly depends on the plastic viscosity.

[0047] As a preferred implementation method, the pressure signal of the pressure sensor is transmitted to the remote monitoring center through its corresponding wireless signal transmitter, so as to realize the real-time remote monitoring of the changes in the workability of concrete during transit. In an embodiment of the present invention, the wireless signal transmitter is a 4G wireless signal transmitter, and the 4G wireless signal transmitter is installed on the outside of the mixer truck drum; in other embodiments, it can also be other wireless signal transmitters that are compatible with the pressure signal of the pressure sensor. Based on the received drum speed (rotation speed), pressure and time relationship data, the remote monitoring center obtains the relationship between the drum speed, rod resistance and transportation time, and then obtains the change of rheological parameters over time during transportation. In addition, the corresponding stress data can be obtained according to the pressure data of the sensor, and the change law of resistance and time can be obtained according to the drum rotation speed and the corresponding stress. The data on the change of pressure, stress, apparent viscosity and temperature over time can all be used as one of the bases for subsequent regulation of concrete workability. Such as Figure 2 As shown in the figure, it is a schematic diagram of the variation of the rod torque with the test time at a certain point in time. The stabilized value can represent the apparent viscosity at this time. Figure 3 The relationship between the rod torque and the rotation speed represents the schematic diagram of the concrete rheological test. Figure 3 R 2 The parameter to be set.

[0048] Furthermore, based on the rheological shear of concrete at different times during transportation, the corresponding apparent viscosity at a certain speed, i.e., flow resistance, can also be calculated. In the embodiment of the present invention, the yield value before transportation and the plastic viscosity are obtained based on the relationship between the resistance of the drum of the testing mixer truck at multiple speeds. During transportation, the apparent viscosity of the concrete at the normal speed of the drum can be characterized by the value of "resistance / speed". The change of apparent viscosity over time can also reflect the change of concrete workability over time.

[0049] As a further design of the present invention, the present invention takes into account that cement hydration in concrete leads to a decrease in water content in the concrete, an increase in solid phase, and an increase in viscosity. The temperature increase caused by hydration leads to an acceleration of the hydration reaction, which also affects the change of concrete workability over time. Therefore, the concrete workability detection method in the mixer truck of the present invention also includes:

[0050] The temperature T of concrete during transportation is measured in real time to establish the relationship between the yield value, plastic viscosity, and apparent viscosity and the temperature T over time. The temperature T includes the temperature of the concrete in the mixer drum, and / or the temperature of the environment inside and outside the mixer drum to obtain the temperature difference between the inside and outside of the mixer drum.

[0051] In actual application, it can be selected adaptively according to the climate environment in the south and the north. For example, in the summer in the south and the winter in the north, the temperature difference between the inside and outside of the mixer truck is large. At this time, the internal and external temperature difference data can be selected to construct the relationship between the yield value, plastic viscosity, and apparent viscosity and temperature T over time.

[0052] In the embodiment of the present invention, a concrete temperature sensor is used to measure the temperature T of concrete during transportation in real time. When measuring the temperature inside the drum of the mixer truck, the concrete temperature sensor faces the inside of the drum and contacts the concrete inside the drum. The transmitter of the temperature sensor signal is arranged outside the drum, and the corresponding temperature signal is transmitted wirelessly.

[0053] It should be noted that the rheological properties and temperature tests of concrete are only related to the properties of the concrete in the cylinder, and have nothing to do with the shape of the cylinder and the loading amount of concrete in the cylinder.

[0054] The data of the rheological shear rod when it rotates with the cylinder and leaves the concrete is judged and eliminated by the calculation software.

[0055] The method for detecting the workability of concrete in a mixer truck of the present invention directly converts the resistance encountered by the concrete during the flow of the mixer truck drum at different times during the rotation of the mixer truck drum into a pressure signal through a rheological shear device placed in the mixer truck drum. Based on the pressure signals corresponding to different times during the rotation of the mixer truck drum, the relationship between the rotation speed of the mixer truck drum and the resistance encountered by the rheological shear rod can be obtained; the rheological shear rod extending into the concrete acts as a shear rod, and shears the concrete while rotating with the drum, and different rotation speeds correspond to different shear resistances. In the rheological sense, the drum rotation speed is proportional to the shear rate, so the relationship between the obtained drum rotation speed of the mixer truck and the resistance encountered by the rheological shear rod can characterize the relationship between the shear rate and shear resistance of the concrete. There is a linear relationship between the shear rate and the shear resistance, so the intercept corresponding to the relationship between the drum rotation speed of the mixer truck and the resistance encountered by the rheological shear rod represents the yield value, and the slope of the straight line represents the plastic viscosity. Based on the yield value and plastic viscosity at different times during transportation, the apparent viscosity at a certain rotation speed is calculated; and the changes in the yield value, plastic viscosity and apparent viscosity over time can reflect the changes in the workability of concrete over time. In this way, the present invention realizes the direct detection of the workability of fresh concrete, which has the advantages of high accuracy and strong real-time performance.

[0056] Furthermore, the present invention takes into account that cement hydration in concrete leads to a decrease in water content, an increase in solid phase, and an increase in viscosity. The temperature increase caused by hydration leads to an acceleration of the hydration reaction, which also affects the change in concrete workability over time. Therefore, the method of the present invention also includes real-time measurement of the temperature T during the transportation of concrete to establish the relationship between the yield value, plastic viscosity, and apparent viscosity and the change in temperature T over time, further improving the accuracy of direct measurement of the workability of fresh concrete.

[0057] Example 2

[0058] Based on Example 1, Example 2 provides a method for regulating the workability of concrete during transportation, comprising:

[0059] A database of the relationship between the rheological properties and workability of concrete of different categories and strength grades under different transportation conditions and changes over time is established in advance. The values ​​in the database are used as standard values ​​for comparison with subsequent real-time measurement values. Through this database, the relationship between the change of rheological properties over time for each concrete product (concrete of different strength grades) under different transportation conditions (concrete mixer truck transportation, transportation time, high and low ambient temperature) can be obtained. Since the performance of engineering concrete categories is different and the transportation conditions cannot be unified, it is necessary to continuously optimize and accurately calculate the correlation based on big data. In an embodiment of the present invention, the database not only includes the yield value, plastic viscosity and apparent viscosity data of a certain concrete at different mixing speeds during transportation, but also includes the data of the pressure change over time measured by the original pressure sensor, and the data of the change of concrete temperature over time under transportation conditions.

[0060] After the freshly mixed concrete produced in the factory is unloaded into the drum of the concrete transport mixer truck, samples are taken according to the quality management regulations for concrete workability test to obtain the initial value of concrete workability. At the set drum speed, the rheological properties of the initial concrete in transportation are measured using the detection method in Example 1 to obtain the initial value of rheological properties; the test data are compared with the relevant concrete standard value data in the database to confirm the initial workability and rheology of the concrete before leaving the factory. When the initial workability meets the requirements, the concrete transport mixer truck leaves the factory.

[0061] After the concrete transport mixer truck leaves the factory, during transportation, the apparent viscosity of the concrete at different times is continuously detected by the workability detection method in the above-mentioned embodiment 1, and when necessary, it is regulated by adding admixtures until it reaches the delivery location. Before delivery and unloading, the rheological properties of the concrete can be tested again at the same rotation speed before leaving the factory to confirm that the workability of the concrete meets the requirements. In the embodiment of the present invention, the rheological shear resistance of the concrete is tested once every rotation of the mixing drum. In other embodiments, the test time interval can also be adjusted according to actual needs.

[0062] As a specific implementation method, after the concrete is loaded and before it is transported, the method in Example 1 can be used to test the relationship between the speed and the shear resistance at several lower speeds to construct a database of the time-varying relationship of the apparent viscosity. During transportation, the mixer truck usually stirs the concrete at a lower speed. During the transportation, the rheological properties of the concrete are detected at regular intervals (for example, 3 minutes, this parameter is adjustable), and the shear resistance at this speed represents the apparent viscosity at this speed. The apparent viscosity calculated by the test during transportation is compared with the apparent viscosity value at the beginning of transportation, and the difference is calculated to determine the trend of the difference over time during the current period. According to the relationship between workability and apparent viscosity, if the trend of the difference over time during this period causes the workability to deteriorate (the apparent viscosity of the concrete increases) and reaches the preset warning value, the program control is triggered to automatically add admixtures to regulate the workability of the concrete to meet the required workability requirements. If during this period of time, only the workability reflected by the partial apparent viscosity difference has deteriorated, an optimization algorithm can be used based on the corresponding yield value, plastic viscosity and original data (including the aforementioned data on pressure, stress, shear resistance and temperature changes over time) to intelligently determine whether automatic addition of admixtures is needed. The optimization algorithm can be an intelligent agent optimization algorithm or an intelligent optimization algorithm such as a neural network.

[0063] In addition, the amount and duration of admixture replenishment can be determined according to the concrete workability target set at the time of delivery, and an optimization algorithm can be used to automatically make the optimal decision, thereby ensuring that the concrete workability meets the requirements when the transport truck arrives at the delivery location.

[0064] In an embodiment of the present invention, an automatic replenishing spraying admixture device is used to automatically replenish admixtures. The automatic replenishing spraying admixture device includes: an admixture liquid storage tank carried on the vehicle and fixed outside the mixing drum, an automatic control spraying system installed at the discharge port of the concrete mixer drum, and an admixture flow metering system. The rheological properties and temperature of the concrete in the mixer drum are continuously measured during transportation. By comparing the measured rheological properties with the required rheological properties, the automatic replenishing spraying admixture device is used to automatically replenish admixtures, so that the rheological properties of the concrete are regulated within a set range.

[0065] As a preferred method, the relationship between the amount of admixture added and the change in workability and apparent viscosity of concrete of different types and strength grades is also constructed, as well as the relationship between the effect of increasing the water-binder ratio of concrete due to the addition of water-based admixtures on the strength of concrete. Based on the constructed relationship, the amount of admixture added each time and the number of times are adjusted to ensure that the apparent viscosity (workability) of the concrete meets the requirements without affecting the concrete strength to meet the design requirements.

[0066] Preferably, the addition of admixtures during the journey is used as the basis for optimizing the concrete mix design. The admixture dosage is optimized based on similar concrete and similar ambient temperatures in big data, as well as an estimate of the transportation time, to avoid excessively increasing the initial admixture dosage, thereby meeting the workability requirements of the concrete while reducing the admixture cost.

[0067] As a preferred implementation, it also includes judging the change trend of concrete temperature over time. If the change trend of concrete temperature over time makes the workability worse and reaches a preset warning value, the program control is triggered to automatically add admixtures to regulate the workability of the concrete. If the concrete temperature rise is not high, the rheological properties do not change much in the direction of increasing viscosity over time, or do not reach the warning value, no admixtures need to be added.

[0068] Preferably, the types of admixtures added during the process are generally water-based high-efficiency water reducers, retarders, slow-setting water reducers and other functional admixtures. For example, in winter construction, early-strength antifreeze agents can be added before concrete unloading.

[0069] As a preference, for high-performance concrete and key project concrete, owners and project supervisors can monitor concrete quality management and concrete workability in real time through information shared online.

[0070] Monitoring and controlling the workability and changes of concrete during production and transportation is an effective measure for factory quality management, including:

[0071] The control room of a concrete plant (or a remote monitoring center) can receive signals wirelessly to monitor the time and actual route of concrete trucks in transit online in real time, and grasp in real time unexpected timeouts that may occur during concrete transportation, including traffic jams on the way and long waits at the construction site for delivery and unloading, etc. Different control measures can be taken according to the different locations and dynamics of the trucks, such as slow rotation during transportation, slow or accelerated mixing while waiting statically, and rapid mixing and homogenization before unloading, etc., to promptly deal with problems reported by drivers or on-site technicians.

[0072] According to the real-time monitoring of the concrete apparent viscosity (or rheological properties such as yield value and plastic viscosity at different times) and temperature changes, determine whether to conduct regulation and intervention. If the contract quality requirements are still not met after the regulation and intervention measures are taken, timely decide on the disposal measures for the concrete in the mixer truck, such as converting it to other uses or transporting it back for disposal, so as to reduce economic losses and prevent concrete engineering quality accidents.

[0073] The method for controlling the workability of concrete during transportation of the present invention automatically and quantitatively sprays admixtures to the concrete in the mixer truck according to the workability requirements and the changing workability under software control according to the program setting, so as to achieve timely fine-tuning or pre-adjustment of the workability of concrete during transportation, and ensure that the workability of concrete meets the design requirements. The present invention can more accurately control the changes in the workability of concrete in transit, further optimize the design and adjustment of the concrete mix ratio, improve the quality level of concrete engineering, and solve the problem of lack of quality monitoring and control during the transportation of concrete.

[0074] Example 3

[0075] The embodiment of the present invention provides a workability detection system for concrete during transportation, comprising:

[0076] The rheological shear device placed in the drum of the mixer truck is used to directly convert the resistance of concrete flow shear at different moments during the rotation of the drum into a pressure signal; wherein the rheological shear device includes a rheological shear rod and a pressure sensor; the rheological shear rod extends into the concrete in the drum, and is used to directly detect the resistance of concrete flow during the rotation of the drum, and the resistance is converted into the pressure of the pressure sensor through the lever principle;

[0077] The rheological parameter calculation module is used to obtain the relationship between the cylinder rotation speed and the resistance of the rheological shear rod at different times based on the pressure signal; the straight line intercept of the relationship represents the yield value, and the straight line slope of the relationship represents the plastic viscosity;

[0078] The workability real-time detection module is used to reflect the workability with yield value and plastic viscosity, obtain the time-varying relationship of the workability during concrete transportation, and realize real-time detection of the workability.

[0079] Further, a temperature sensor is included;

[0080] The temperature sensor is used to measure the temperature T of concrete in real time during transportation, so as to establish the relationship between the yield value, plastic viscosity and temperature T over time; wherein the temperature T includes the temperature of the concrete in the drum of the mixer truck, and / or the ambient temperature inside and outside the drum of the mixer truck to obtain the temperature difference between the inside and outside of the drum of the mixer truck.

[0081] For the specific implementation of each of the above modules, devices, or components, please refer to the corresponding description in Example 1 and will not be repeated here.

[0082] Example 4

[0083] The embodiment of the present invention provides a workability control system during concrete transportation, comprising:

[0084] The database construction module is used to pre-establish a database of the time-varying relationship between the apparent viscosity of concrete of different categories, strength grades and workability requirements under different transportation conditions; and to establish a database of the correlation between concrete workability and apparent viscosity.

[0085] The workability detection system is used to detect the workability of concrete at different times during transportation in real time until it reaches the delivery location; wherein the workability detection system is the workability detection system during transportation of concrete in Example 3.

[0086] The calculation module is used to calculate the corresponding apparent viscosity based on the yield value and plastic viscosity detected in real time at regular intervals during transportation; and compare the apparent viscosity with the corresponding apparent viscosity in the database to obtain the trend of the apparent viscosity difference over time during this period of time.

[0087] The automatic replenishing and spraying admixture device is used to automatically replenish admixtures when the apparent viscosity difference changes with time during the period, causing the workability to deteriorate and reaching a preset warning value, so as to adjust the workability of the concrete in real time.

[0088] The specific implementation method or structure of each module or device can be found in the description of the corresponding embodiment and will not be repeated here.

[0089] The present invention directly tests the rheological properties of ready-mixed concrete transported by mixer trucks on the way, and measures, monitors, predicts and regulates the concrete workability and its changes through the relationship between the rheological properties and workability, and the influence of the ambient temperature and cement hydration on this relationship, so as to meet the concrete workability and concrete strength performance required by the construction. As long as the various changes in the rheological properties of concrete are within the spirit and scope of the present invention defined and determined by the protected technical solution, these changes with cement hydration, environment and time are obvious, and all inventions and creations using the concept of the present invention are protected.

[0090] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting the workability of concrete in a mixer truck, characterized in that: include: A rheological shear device placed in the drum of a mixer truck is used to directly convert the resistance of concrete flowing at different moments during the rotation of the drum into a pressure signal; wherein, the rheological shear device comprises the rheological shear rod and a pressure sensor; the rheological shear rod extends into the concrete in the drum, and is used to directly detect the resistance of concrete during shear flow during the rotation of the drum, and the resistance is converted into the pressure of the pressure sensor through the lever principle; the pressure of the pressure sensor is used to characterize the pressure generated by the concrete flowing on the drum at different moments during the rotation of the drum of the mixer truck during transportation; the pressure sensor is arranged at the bottom of the drum and passes through the drum; the rheological shear rod is immersed in the concrete; the rheological shear rod is in the shape of a sheet rod, and the length and cross-sectional shape of the sheet rod are adjusted according to the resistance of different concretes during the shear flow; Based on the pressure signal, the relationship between the cylinder rotation speed and the resistance of the rheological shear rod at different times is obtained; the straight line intercept of the relationship represents the yield value, and the straight line slope of the relationship represents the plastic viscosity; The yield value and the plastic viscosity are used to reflect the workability, and the time-varying relationship of the workability during concrete transportation is obtained, thereby achieving real-time detection of the workability.

2. The method for detecting the workability of concrete in a mixer truck according to claim 1, characterized in that: Also includes: The temperature T of concrete during transportation is measured in real time to establish the relationship between the yield value, the plastic viscosity, the apparent viscosity and the temperature T over time; wherein the temperature T includes the temperature of the concrete in the drum of the mixer truck, and / or the temperature T also includes the ambient temperature inside and outside the drum of the mixer truck to obtain the temperature difference between the inside and outside environments of the drum of the mixer truck.

3. A method for controlling the workability of concrete in a mixer truck, characterized in that: include: Establish in advance a database of the time-varying relationship of the apparent viscosity of concrete of different categories, strength grades and workability requirements under different transportation conditions; The concrete workability detection method in a mixer truck as claimed in claim 1 or 2 is used to detect the workability of the concrete at different times during transportation in real time until it reaches the delivery location; During transportation, at regular intervals, the corresponding apparent viscosity is calculated based on the yield value and plastic viscosity detected in real time; and comparing the apparent viscosity with the corresponding apparent viscosity in the database to obtain the trend of the apparent viscosity difference over time during the period; During this period, the trend of the apparent viscosity difference changing with time causes the workability to deteriorate, and when it reaches the preset warning value, the admixture is automatically added to adjust the workability of the concrete in real time.

4. The workability control method according to claim 3, characterized in that: During this period of time, the workability reflected by some of the apparent viscosity differences deteriorates, and the workability control method further comprises: Based on the apparent viscosity difference of this part, as well as the yield value and plastic viscosity corresponding to the apparent viscosity difference of this part and the pressure data measured by the pressure sensor, an optimization algorithm is used to decide whether automatic supplementation of additives is required.

5. The workability control method according to claim 3 or 4, characterized in that: The type of admixture, the amount of each addition and the number of additions are determined automatically by an optimization algorithm according to the concrete workability target set at the time of delivery.

6. The workability control method according to claim 5, characterized in that: It also includes real-time monitoring of the time the concrete mixer truck is in transit, the actual route, and the unloading delivery location and time to assist in regulating the workability of the concrete.

7. A concrete workability detection system in a mixer truck, characterized in that: include: The rheological shear device placed in the drum of a mixer truck is used to directly convert the resistance of the rheological shear rod when the concrete flows at different moments during the rotation of the drum into a pressure signal; wherein, the rheological shear device comprises the rheological shear rod and a pressure sensor; the rheological shear rod extends into the concrete in the drum, and is used to directly detect the resistance of the concrete during shear flow during the rotation of the drum, and the resistance is converted into the pressure of the pressure sensor through the lever principle; the pressure of the pressure sensor is used to characterize the pressure generated on the drum when the concrete flows at different moments during the rotation of the drum of the mixer truck during transportation; the pressure sensor is arranged at the bottom of the drum and passes through the drum; the rheological shear rod is immersed in the concrete; the rheological shear rod is in the shape of a sheet rod, and the length and cross-sectional shape of the sheet rod are adjusted according to the resistance of different concretes during the shear flow; A rheological parameter calculation module, for obtaining the relationship between the cylinder rotation speed and the resistance of the rheological shear rod at different times based on the pressure signal; the straight line intercept of the relationship represents the yield value, and the straight line slope of the relationship represents the plastic viscosity; The workability real-time detection module is used to reflect the workability by using the yield value and the plastic viscosity, obtain the time-varying relationship of the workability during concrete transportation, and realize the real-time detection of the workability.

8. The concrete workability detection system in a mixer truck according to claim 7, characterized in that: Also includes a temperature sensor; The temperature sensor is used to measure the temperature T of concrete in real time during transportation, so as to establish the relationship between the yield value, the plastic viscosity, the apparent viscosity and the temperature T changing with time; wherein the temperature T includes the temperature of the concrete in the drum of the mixer truck, and / or the temperature T also includes the temperature of the internal and external environments of the drum of the mixer truck to obtain the temperature difference between the internal and external environments of the drum of the mixer truck.

9. A concrete workability control system in a mixer truck, characterized in that: include: A database construction module is used to pre-establish a database of the time-varying relationship of the apparent viscosity of concrete of different categories, strength grades and workability requirements under different transportation conditions; A workability detection system for detecting the workability of concrete at different times during transportation in real time until it reaches the delivery location; wherein the workability detection system is the concrete workability detection system in a mixer truck as claimed in claim 7 or 8; A calculation module is used to calculate the corresponding apparent viscosity based on the yield value and plastic viscosity detected in real time at regular intervals during transportation; and compare the apparent viscosity with the corresponding apparent viscosity in the database to obtain the trend of the apparent viscosity difference over time during the period; The automatic replenishing and spraying admixture device is used to automatically replenish admixtures when the apparent viscosity difference changes with time during the period, causing the workability to deteriorate and reaching a preset warning value, so as to adjust the workability of the concrete in real time.

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