Cement-based material rheological property prediction method and system considering stirring time influence

Abstract

The invention provides a cement-based material rheological property prediction method and system considering the influence of stirring time, and relates to the technical field of cement-based materials, and the method comprises the steps: obtaining the physical property parameters of cement paste, and the hydration heat data and rheological parameters under the set stirring time; according to the hydration heat data and the rheological parameters, calculating to obtain a time-dependent hydration degree and a structuring rate of the cement paste; calculating an initial solid volume fraction and a hydration product volume fraction of the cement paste based on the physical characteristic parameters of the cement paste; predicting the aging yield stress of the cement paste based on the aging hydration degree, the structuring rate, the initial solid volume fraction and the hydration product volume fraction; and adjusting and optimizing the rheological property of the cement paste according to the predicted change of the aging yield stress, and completing the prediction of the influence of the stirring time on the rheological property of the neat paste.

Description

Technical Field

[0001] The present disclosure relates to the technical field of cement-based materials, and particularly to a method and system for predicting the rheological properties of cement-based materials considering the influence of mixing time. Background Art

[0002] The statements in this part merely provide background technical information related to the present disclosure and do not necessarily constitute prior art.

[0003] With the rapid development of modern construction projects towards high efficiency and greening, the precise regulation of the rheology of cement-based materials has become the key to building quality and engineering durability. In processes such as pumping and pouring, the time-dependent change in the yield stress of neat cement paste directly affects its flow characteristics and structural stability. Mixing, as the core link in material preparation, not only disperses particles through mechanical shear and promotes the hydration reaction, but also significantly regulates the formation and evolution of the internal structure of the paste. However, the length of the mixing time may lead to differences in the degree of hydration and fluctuations in the structuring rate, thereby causing dynamic mismatch problems in the yield stress and affecting the adaptability of the construction window.

[0004] The existing technical solutions for the study of the rheological properties of neat cement paste mostly rely on macroscopic tests under a fixed mixing time, lacking in-depth analysis of the coupling mechanism between mixing time and hydration kinetics; in addition, there is a lack of research on the time-dependent yield stress change of neat cement paste under different mixing times, which cannot provide theoretical support for the stability of the rheological properties of neat cement paste under complex working conditions, and increases material waste and energy consumption caused by mismatched mixing parameters, and cannot be better applied to major projects such as super high-rise buildings and undersea tunnels, reducing material adaptability and service life. Summary of the Invention

[0005] In order to solve the above problems, the present disclosure proposes a method and system for predicting the rheological properties of cement-based materials considering the influence of mixing time. Based on the physical properties and degree of hydration of the cementitious materials, the time-dependent yield stress change of neat cement paste under different mixing times is optimized, and the rheological characteristics of the cement paste are adjusted and optimized according to the time-dependent change in the yield stress, so as to complete the prediction of the rheological behavior of neat cement paste of cement-based materials under complex working conditions.

[0006] According to some embodiments, the present disclosure adopts the following technical solutions:

[0007] A method for predicting the rheological properties of cement-based materials considering the influence of mixing time, comprising:

[0008] Obtaining the physical property parameters of the cement paste, the hydration heat data and the rheological parameters under a set mixing time;

[0009] Calculating the degree of hydration over time and the structuring rate of the cement paste according to the hydration heat data and the rheological parameters;

[0010] Based on the physical property parameters of the cement paste, the initial solid volume fraction and the hydrated product volume fraction of the cement paste are calculated;

[0011] Based on the hydration degree over time, the structuring rate, the initial solid volume fraction, and the hydrated product volume fraction, the yield stress of the cement paste over time is predicted; the rheological properties of the cement paste are adjusted and optimized according to the predicted change in the yield stress over time, and the prediction of the influence of the mixing time on the rheological properties of the neat paste is completed.

[0012] According to some embodiments, the present disclosure adopts the following technical solutions:

[0013] A prediction system for the rheological properties of cement-based materials considering the influence of mixing time, comprising:

[0014] A data acquisition module for acquiring the physical property parameters of the cement paste, as well as the hydration heat data and rheological parameters at a set mixing time;

[0015] A calculation module for calculating the hydration degree over time and the structuring rate of the cement paste according to the hydration heat data and rheological parameters; based on the physical property parameters of the cement paste, calculating the initial solid volume fraction and the hydrated product volume fraction of the cement paste;

[0016] A prediction module for predicting the yield stress of the cement paste over time based on the hydration degree over time, the structuring rate, the initial solid volume fraction, and the hydrated product volume fraction; adjusting and optimizing the rheological properties of the cement paste according to the predicted change in the yield stress over time, and completing the prediction of the influence of the mixing time on the rheological properties of the neat paste.

[0017] According to some embodiments, the present disclosure adopts the following technical solutions:

[0018] A computer program product, including a computer program, which when executed by a processor implements the prediction method for the rheological properties of cement-based materials considering the influence of mixing time.

[0019] According to some embodiments, the present disclosure adopts the following technical solutions:

[0020] A computer program product, including a computer program, which when executed by a processor implements the prediction method for the rheological properties of cement-based materials considering the influence of mixing time.

[0021] According to some embodiments, the present disclosure adopts the following technical solutions:

[0022] An electronic device, comprising: a processor, a memory, and a computer program; wherein, the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device runs, the processor executes the computer program stored in the memory so that the electronic device executes the method for predicting the rheological properties of cement-based materials considering the influence of mixing time as described above.

[0023] Compared with the prior art, the beneficial effects of the present disclosure are as follows:

[0024] The method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to the present disclosure realizes the dynamic prediction and rapid optimization of the workability of cement-based material slurries based on raw material physical properties (such as specific surface area, particle size distribution) and construction conditions (such as environmental temperature and humidity, pumping pressure). This research can not only provide theoretical support for the stability of the rheological properties of neat cement slurries under complex working conditions, but also promote the development of intelligent mixing processes, reduce material waste and energy consumption caused by mismatched mixing parameters, and is of great significance for improving the material adaptability and service life of major projects such as super high-rise buildings and undersea tunnels.

[0025] The method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to the present disclosure studies the change of the yield stress of neat cement over time under different mixing times, optimizes the yield stress of the cement slurry over time, provides a theoretical method for predicting and optimizing the influence of mixing time on the rheological properties of neat cement, realizes the accurate prediction of the yield stress of the cement slurry by constructing a dynamic model of mixing time and rheological parameters, quantifies the hydration and flocculation competition mechanism, reduces the prediction error by more than 40%, generates the allowable mixing time window under different working conditions, and optimizes the pumping stability. Description of the Drawings

[0026] The specification drawings forming a part of the present disclosure are used to provide a further understanding of the present disclosure. The schematic embodiments and descriptions thereof of the present disclosure are used to explain the present disclosure and do not constitute an improper limitation to the present disclosure.

[0027] Figure 1 It is a flow chart of the method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to an embodiment of the present disclosure;

[0028] Figure 2 It is a schematic diagram of the detailed steps of the method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to an embodiment of the present disclosure;

[0029] Figure 3 It is a schematic diagram of the relationship between the experimental values and calculated values of the yield stress over time under different mixing times according to an embodiment of the present disclosure;

[0030] Among them, Figure 3 in (a) is a schematic diagram of the relationship between the experimental values and calculated values of the yield stress over time when mixing for 4 minutes;Figure 3 In (b) is a schematic diagram of the relationship between the experimental value and the calculated value of the time-dependent yield stress at 8 minutes of stirring; Figure 3 In (c) is a schematic diagram of the relationship between the experimental value and the calculated value of the time-dependent yield stress at 12 minutes of stirring;

[0031] Figure 4 This is a structural block diagram of a prediction system for the rheological properties of cement-based materials considering the influence of stirring time according to an embodiment of the present disclosure. Specific embodiments

[0032] The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present disclosure belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] Example 1

[0036] The prediction method for the rheological properties of cement-based materials considering the influence of stirring time according to the present disclosure provides a theoretical method for predicting and optimizing the influence of stirring time on the rheological properties of neat cement by accurately predicting the physical properties and degree of hydration of cementitious materials and optimizing the time-dependent yield stress of cement paste. The method steps include:

[0037] Step 1: Obtain the physical property parameters of the cement paste, the hydration heat data, and the rheological parameters at a set stirring time;

[0038] Step 2: Calculate the time-dependent degree of hydration and the structuring rate of the cement paste based on the hydration heat data and the rheological parameters;

[0039] Step 3: Calculate the initial solid volume fraction and the hydrated product volume fraction of the cement paste based on the physical property parameters of the cement paste;

[0040] Step 4: Predict the time-dependent yield stress of the cement paste based on the time-dependent degree of hydration, the structuring rate, the initial solid volume fraction, and the hydrated product volume fraction; adjust and optimize the rheological properties of the cement paste according to the predicted change in the time-dependent yield stress to complete the prediction of the influence of stirring time on the rheological properties of neat cement.

[0041] As an embodiment, the method for predicting the rheological properties of cement-based materials considering the influence of mixing time in the present disclosure studies the change of the time-dependent yield stress of cement paste under different mixing times, providing a theoretical method for predicting and optimizing the influence of mixing time on the rheological properties of the paste. The specific implementation process is as follows:

[0042] Step 1: Obtain the correlation data between mixing time, heat of hydration, and rheological parameters;

[0043] Specifically, by using the heat of hydration test, the heat flow and cumulative heat release of the cement paste samples under different mixing times are measured to obtain the time-dependent heat release rate of the cement paste, which specifically includes:

[0044] Load the cement powder into the sample bottle and the water into the syringe or water injection device; place an equal mass of inert reference material (such as alumina) in the channel; start the automatic water injection system of the instrument to inject water into the cement sample and immediately start recording data; the software monitors the heat release rate (W / g) in real time; export the time-heat release rate curve and the cumulative heat release amount to obtain the time-dependent heat release rate of the cement paste.

[0045] Furthermore, by using the rheometer test, the rheological parameters of the cement paste samples under different mixing times are measured. The prepared paste is placed in the rheometer and tested at a constant low shear rate, and the change of shear stress with time is monitored. The maximum value of the shear stress is taken as the static yield stress.

[0046] Step 2: Calculate the time-dependent degree of hydration and the structuring rate of the cement paste according to the obtained heat of hydration and rheological parameters;

[0047] Specifically, the paste is sheared at a fixed low shear rate, and the maximum stress value in the curve of shear stress changing with time is taken as the static yield stress. The static yield stresses at different standing times obtained in the rheometer test are linearly fitted using Origin software, and then the fitting slope, that is, the structuring rate, is obtained. The relationship between the static yield stress and the standing time is:

[0048] τ0(t rest )=τ 0.0 +A thix t rest

[0049] where τ 0.0 is the initial yield stress; A thix is the structure establishment rate; t rest is the standing time; τ0(t rest ) is the static yield stress.

[0050] Further, the hydration degree α(t) over time obtained by calculating the hydration heat release rate and the cumulative heat release amount obtained in the hydration heat test using the hydration degree formula is as follows:

[0051]

[0052] where Q(t) is the change in the cumulative hydration heat release of the cementitious material measured by the hydration heat test over time; Q total is the theoretical ultimate heat release amount of the cementitious material. It is calculated by weighted according to the cement chemical composition, that is, Q total = Σ(ω i ·Q i ), ω i is the mass fraction of mineral i, and Q i is the heat release amount per unit mass of complete hydration of mineral i (for example, C3S≈500J / g, C2S≈250J / g).

[0053] Step 3: Based on the physical property parameters of the cement paste, calculate the initial solid volume fraction and the hydration product volume fraction of the cement paste;

[0054] Specifically, the physical property parameters of the cement paste include the cementitious material density, particle size distribution, and cementitious material chemical composition. Based on the physical property parameters of the cement paste, calculate the hydration product volume fraction (the volume occupied by the effective solids in the hydration products) of the cement paste:

[0055]

[0056] where w / c is the water-cement ratio, ρ w and ρ c are the water density and the cement density ratio respectively.

[0057] Further, based on the physical property parameters of the cement paste, calculate the initial solid volume fraction of the cement paste:

[0058]

[0059] where V cement is the solid volume in the neat paste, and V water is the liquid volume.

[0060] Step 4: Based on the hydration degree over time, the structuring rate, the initial solid volume fraction, and the hydration product volume fraction, predict the yield stress over time of the cement paste; adjust and optimize the rheological properties of the cement paste according to the predicted change in the yield stress over time to complete the prediction of the influence of the mixing time on the rheological properties of the neat paste.

[0061] Specifically, the formula for the yield stress over time of the cement paste:

[0062]

[0063] Among them, m is a pre-factor related to the particle size distribution, and its value is usually 20 to 40; A0 is the non-delayed Hamaker constant, and its value is usually 1.0×10 -20 to 1.6×10 -20 J; a * is the radius of curvature of the contact point, which is related to the surface roughness of the particle, and its value is usually 200 to 500 nm; d0 is the initial diameter of the unhydrated cement particle, and its value is usually 10×10 -6 ; H is the surface spacing of the particles at the contact point. When there is a water reducer, its value is usually 5 to 20 nm; χ is the volume fraction coefficient of the hydration product, where p is the solid volume fraction of the hydration product, v n is the specific volume of bound water, v c is the specific volume of cement, w n / c is the mass ratio of the reacted water to the cement, and the theoretical value (complete hydration of C3S); w n / c≈0.24; φ perc is the percolation threshold, and its value is usually 0.2 to 0.4 (i.e., 20%–40%); φ m is the maximum packing fraction, which is obtained through the packing density test, and its value is usually 0.55 to 0.6.

[0064] As an example, according to the predicted change of the yield stress over time at different mixing times, the parameters (such as the mixing time) are optimized based on the model. If the model shows that τ0 first decreases and then stabilizes with the mixing time, then select the minimum time τ when τ0 reaches the stable value stable , to avoid increased energy consumption or air bubble introduction caused by overmixing. If τ0 continuously increases with the mixing time, it is necessary to balance the construction time window and the rheological properties, and select the time point when τ0 does not exceed the threshold. Adjust and optimize the rheological properties of the cement paste to complete the prediction of the influence of the mixing time on the rheological properties of the neat paste.

[0065] As an example, the embodiments of the present disclosure are introduced in detail taking the neat paste as an example; the mix proportion of the cement neat paste used is shown in Table 1.

[0066] Table 1 Mix proportion of cement neat paste

[0067] Number Stirring time (min) <![CDATA[Cement (kg / m 3 )]]> <![CDATA[Water (kg / m 3 )]]> <![CDATA[Water reducing agent (kg / m 3 )]]> M4 4 336.65 70.66 11.78 M8 8 336.65 70.66 11.78 M12 12 336.65 70.66 11.78

[0068] The hydration rate curve of each group of cement paste in Table 1 is tested by an isothermal calorimeter, and the degree of hydration is calculated through the hydration heat formula; the curve of shear stress and time of each group of cement paste in Table 1 is tested by a rheometer, and the maximum stress value in the curve of shear stress changing with time is taken as the static yield stress, and the structuring rate is obtained by fitting the standing time and the static yield stress at different standing times.

[0069] The obtained data is passed through the formula for the yield stress of cement paste over time

[0070] The relationships between the experimental values and calculated values of the yield stress over time for each group are as follows Figure 3 As shown, it can be obtained that there is a high degree of agreement between the calculated values and experimental values of the relative yield stress and plastic viscosity

[0071] The embodiments of the present disclosure solve the problem in engineering that the fixed mixing process is relied on and the mix ratio needs to be repeatedly tested and adjusted, saving test costs and time; according to the physical properties such as the hydration heat degree, structuring rate of the cement paste, and the particle size distribution and density of the cement, the time-dependent evolution law of the yield stress and viscosity of the paste can be accurately predicted, significantly improving the stability of the rheological properties of the mixture; at the same time, according to the dynamic requirements of the rheological properties in the construction scenario (such as changes in pumping pressure, fluctuations in environmental temperature and humidity) or differences in raw material characteristics, the mixing time parameters can be quickly adjusted to achieve the coordinated optimization of the fluidity, thixotropic recovery ability and long-term structural strength of the paste, meeting the high-efficiency construction requirements of complex engineering scenarios

[0072] Example 2

[0073] In an embodiment of the present disclosure, a prediction system for the rheological properties of cement-based materials considering the influence of mixing time is provided, including

[0074] A data acquisition module for acquiring the physical property parameters of the cement paste, as well as the hydration heat data and rheological parameters under a set mixing time

[0075] A calculation module for calculating the degree of hydration over time and the structuring rate of the cement paste based on the hydration heat data and rheological parameters; calculating the initial solid volume fraction and the volume fraction of the hydration product of the cement paste based on the physical property parameters of the cement paste

[0076] A prediction module for predicting the yield stress of the cement paste over time based on the degree of hydration over time, the structuring rate, the initial solid volume fraction, and the volume fraction of the hydration product; adjusting and optimizing the rheological properties of the cement paste according to the predicted change in the yield stress over time to complete the prediction of the influence of mixing time on the rheological properties of the neat paste

[0077] Example 3

[0078] In an embodiment of the present disclosure, a computer program product is provided, including a computer program, which when executed by a processor implements the method for predicting the rheological properties of cement-based materials considering the influence of mixing time

[0079] Example 4

[0080] In one embodiment of the present disclosure, a non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the prediction method for the rheological properties of cement-based materials considering the influence of mixing time is implemented.

[0081] Embodiment 5

[0082] In one embodiment of the present disclosure, an electronic device is provided, including: a processor, a memory, and a computer program; wherein, the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device runs, the processor executes the computer program stored in the memory so that the electronic device executes the prediction method for the rheological properties of cement-based materials considering the influence of mixing time.

[0083] The present disclosure is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in one or more flows and / or one or more blocks. Figure 1 one or more flows and / or Figure 1 one or more blocks

[0084] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows and / or one or more blocks. Figure 1 one or more flows and / or Figure 1 one or more blocks

[0085] Although the specific implementation manners of the present disclosure have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present disclosure. Those skilled in the art should understand that, based on the technical solutions of the present disclosure, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present disclosure.

Claims

1. A method for predicting the rheological properties of cement-based materials considering the influence of mixing time, characterized in that, Including: Obtaining the physical property parameters of the cement paste, as well as the hydration heat data and rheological parameters under a set mixing time; Calculating the degree of hydration with time and the structuring rate of the cement paste based on the hydration heat data and rheological parameters; Calculating the initial solid volume fraction and the volume fraction of hydration products of the cement paste based on the physical property parameters of the cement paste; Predicting the yield stress with time of the cement paste based on the degree of hydration with time, the structuring rate, the initial solid volume fraction, and the volume fraction of hydration products; adjusting and optimizing the rheological properties of the cement paste according to the predicted change in the yield stress with time, and completing the prediction of the influence of mixing time on the rheological properties of neat cement paste.

2. The method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to claim 1, wherein Obtain the physical property parameters of the cement paste, as well as the hydration heat data and rheological parameters at a set mixing time, including: using a hydration heat test to measure the heat flow and cumulative heat release of the cement paste at different mixing times, and the hydration heat release rate Q(t) and cumulative heat release Q obtained from the hydration heat test total The degree of hydration α(t) over time calculated using the degree of hydration formula is as follows: Among them, Q(t) is the change of the cumulative hydration heat release of the cementitious material measured by the hydration heat test with time; Q total is the theoretical ultimate heat release of the cementitious material.

3. The method for predicting the rheological properties of cement-based materials considering the influence of mixing time as described in claim 1, wherein, Shearing the paste at a fixed low shear rate, taking the maximum stress value in the shear stress vs. time curve as the static yield stress, and linearly fitting the static yield stresses at different rest times obtained in the rheometer test using Origin software to obtain the fitting slope, i.e., the structuring rate.

4. The method for predicting the rheological properties of cement-based materials considering the influence of mixing time as claimed in claim 1, wherein Obtaining the physical property parameters of the cement paste, where the physical property parameters of the cement paste include the density of the cementitious material, the particle size distribution, and the chemical composition of the cementitious material, and calculating the volume fraction of hydration products based on the physical property parameters of the cement paste: where w / c is the water-cement ratio, ρ w and ρ c are the water density and the cement density ratio, respectively.

5. The method for predicting the rheological properties of cement-based materials considering the influence of stirring time as claimed in claim 1, wherein Calculating the initial solid volume fraction of the cement paste based on the physical property parameters of the cement paste: Among them, V cement is the solid volume in the neat paste, and V water is the liquid volume.

6. The method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to claim 1, characterized in that, Predicting the yield stress with time of the cement paste based on the degree of hydration with time, the structuring rate, the initial solid volume fraction, and the volume fraction of hydration products, including: where m is a pre-factor related to the particle size distribution; A0 is the non-retarded Hamaker constant; a * is the radius of curvature of the contact point, related to the surface roughness of the particle; d0 is the initial diameter of the unhydrated cement particle; H is the particle surface spacing at the contact point; χ is the volume fraction coefficient of the hydration product; φ perc is the percolation threshold; φ m is the maximum packing fraction, the densest packing volume fraction of the particles without external force. It can be obtained by dry powder packing density test, and the actual value of this for cement particles is between 0.55 and 0.

6.

7. A prediction system for the rheological properties of cement-based materials considering the influence of mixing time, characterized in that, Including: A data acquisition module for obtaining the physical property parameters of the cement paste, as well as the hydration heat data and rheological parameters under a set mixing time; A calculation module for calculating the degree of hydration with time and the structuring rate of the cement paste based on the hydration heat data and rheological parameters; calculating the initial solid volume fraction and the volume fraction of hydration products of the cement paste based on the physical property parameters of the cement paste; A prediction module for predicting the yield stress with time of the cement paste based on the degree of hydration with time, the structuring rate, the initial solid volume fraction, and the volume fraction of hydration products; adjusting and optimizing the rheological properties of the cement paste according to the predicted change in the yield stress with time, and completing the prediction of the influence of mixing time on the rheological properties of neat cement paste.

8. A computer program product comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to any one of claims 1-6.

9. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, it implements the method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to any one of claims 1-6.

10. An electronic device, characterized in that, Including: A processor, a memory, and a computer program; wherein, the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device runs, the processor executes the computer program stored in the memory so that the electronic device executes and implements the method for predicting the rheological properties of cement-based materials considering the influence of mixing time according to any one of claims 1-6.

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