Method and system for representing bleeding of fresh cement paste

Abstract

The invention discloses a method and system for characterizing fresh cement paste bleeding, and the method comprises the steps: firstly selecting a bleeding process of fresh cement paste as a research object, obtaining scatter test data of bleeding amount changing along with time, then building a time-dependent model for characterizing the bleeding process of the fresh cement paste, deducing an analytical solution, and combining the test data to obtain a time-dependent model for characterizing the bleeding process of the fresh cement paste. Various parameters of the time-dependent model are determined, the bleeding curve of the fresh cement paste is quantified, the change rule of the bleeding process is simulated, and practical engineering application is guided. According to the method for representing the bleeding of the fresh cement paste, a time-dependent self-weight consolidation model is adopted, an analytical solution is clear, calculation is easy and convenient, simulation precision is high, the method has a wide engineering application background, and an effective theoretical tool can be provided for representing the bleeding process of the cement paste.

Description

Technical Field

[0001] This invention relates to construction quality testing technology for concrete materials, and in particular to a method and system for characterizing the bleeding of fresh cement paste. Background Technology

[0002] As a core component of modern construction engineering, the performance of cementitious materials directly determines the durability and safety of the engineering structure. However, in the early stages of construction, the bleeding phenomenon commonly found in fresh cement paste often becomes a key factor affecting the uniformity and mechanical properties of the material. Bleeding is defined as the process by which solid particles in the cementitious material settle downwards, while free water migrates to the surface, forming a free water layer. It is mainly affected by the composition and proportion of the cementitious material. Bleeding not only affects the rheological properties of fresh cement paste during construction but also leads to uneven distribution of its components, thereby increasing the porosity of the concrete structure surface and reducing its strength and wear resistance.

[0003] To accurately characterize the bleeding process of fresh cement paste and mitigate its adverse effects, researchers developed a mathematical model based on the self-weight consolidation theory commonly used in soil mechanics. However, existing experimental results indicate that applying the homogeneous consolidation theory is insufficient to characterize the bleeding process of fresh cement paste. Temperature variations, cement hydration processes, and particle rearrangement lead to significant heterogeneity in the bleeding process, resulting in a pronounced time-dependent characteristic of the cement paste's bleeding process.

[0004] Currently, the bleeding process of cement slurry has become a key concern in engineering construction. While some devices have been developed to measure cement slurry bleeding, they cannot effectively characterize the bleeding process or predict it based on existing data. Summary of the Invention

[0005] Purpose of the invention: One objective of this invention is to provide a method and system for characterizing the bleeding of fresh cement paste, which uses a time-dependent self-weight consolidation model to characterize the change in the amount of bleeding of fresh cement paste over time.

[0006] Technical solution: The method described in this invention includes the following steps:

[0007] The bleeding process of fresh cement paste was selected as the research object, and scattered experimental data of the change of the bleeding amount of fresh cement paste over time were obtained during the observation period.

[0008] A time-dependent self-weight consolidation model characterizing the bleeding of fresh cement paste was established, and the analytical solution of the model was derived. Based on the analytical solution of the model, the bleeding amount and bleeding rate of the cement paste were obtained by further integration.

[0009] The parameters of the time-dependent self-weight consolidation model were obtained by fitting the experimental data.

[0010] Based on the model parameters obtained from the fitting, the variation curve of the bleeding amount of fresh cement paste was simulated.

[0011] Furthermore, the experimental data show the variation characteristics of the amount of water bleeding in fresh cement paste as time increases during the observation period.

[0012] Furthermore, a time-dependent self-weight consolidation model characterizing the bleeding of fresh cement paste is established, and the analytical solution of the model is derived; including:

[0013] The time-dependent self-weight consolidation model is as follows:

[0014] ;

[0015] in, For cement paste at high and time Porosity below For time, For height, h is the total height of the cement paste. As a time scale factor, Let be the bleeding coefficient; based on the fundamental properties of partial differential equations, the analytical solution of the time-dependent self-weight consolidation model is derived as follows:

[0016] ;

[0017] in, These are parameters of the cement paste, obtained directly through fitting. The initial porosity, For the terms in the summation of the series.

[0018] Furthermore, the amount and rate of water leakage are obtained from the analytical solution of the model; including:

[0019] Bleeding of cement paste Represented as:

[0020] ;

[0021] in, For cement paste parameters, This represents the total height of the cement paste. For the terms of the summation of the series, The permeability coefficient, For time, For time scale factors;

[0022] Perfusion rate for:

[0023] .

[0024] Furthermore, the parameters of the time-dependent self-weight consolidation model were fitted using the nonlinear least squares method, including: cement paste parameters. , water secretion coefficient and time scale factor .

[0025] Furthermore, based on the obtained model parameters, the curve of the bleeding volume of fresh cement paste changing over time was simulated.

[0026] The system of the present invention includes:

[0027] The data acquisition unit selected the bleeding process of fresh cement paste as the research object and conducted experiments to obtain scatter plot test data on the change of the amount of cement paste sample bleeding over time within the observation period.

[0028] The model building unit is used to establish a time-dependent self-weight consolidation model characterizing the bleeding of fresh cement paste and derive the analytical solution of the model; the bleeding amount and bleeding rate of the cement paste are obtained by further integration based on the analytical solution of the model.

[0029] The parameter fitting unit is used to combine the experimental data of the bleeding amount of cement paste sample with time in the data acquisition unit to fit the parameters of the time-dependent self-weight consolidation model in the model construction unit.

[0030] The variation curve acquisition unit is used to simulate the variation curve of cement paste bleeding based on the model parameters obtained by fitting.

[0031] The present invention also provides an electronic device, including a memory, a processor, and a computer program / instructions stored in the memory and executable on the processor, wherein the computer program / instructions, when executed by the processor, implement the steps of the method for characterizing the bleeding of fresh cement paste.

[0032] The present invention also provides a computer-readable storage medium storing computer instructions, which, when invoked, are used to perform the steps of the method for characterizing the bleeding of fresh cement paste.

[0033] The present invention also provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the method for characterizing the bleeding of fresh cement paste.

[0034] Beneficial Effects: Compared with existing technologies, the significant technical effects of this invention are as follows: Based on a process characterizing the bleeding of fresh cement paste as the research object, experimental data on the change of cement paste bleeding volume over time at different times are obtained. Then, a time-dependent self-weight consolidation model is established, an analytical solution is derived, and the parameters of the time-dependent self-weight consolidation model are determined by combining experimental data. Compared with the traditional self-weight consolidation model, the model of this invention can accurately quantify the bleeding curve of fresh cement paste and accurately simulate the change law of cement paste bleeding over time. In the method of this invention, a power-law time-dependent function is adopted, the analytical solution is clear, the calculation is simple, the simulation accuracy is high, and it has a wide range of engineering applications, providing an effective theoretical tool for controlling the quality of concrete construction. Attached Figure Description

[0035] Figure 1 This is a flowchart of the method of the present invention;

[0036] Figure 2 This is a comparison chart showing the data of water bleeding of a certain sulfoaluminate cement paste fitted by the method model of this invention and the traditional self-weight consolidation model.

[0037] Figure 3 This is a comparison chart showing the data of water bleeding in a certain silicate cement paste fitted by the method model of this invention and the traditional self-weight consolidation model. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0039] This invention aims to establish a novel time-dependent self-weight consolidation model that characterizes the bleeding process of fresh cement paste, enabling the determination of the general law governing the change of bleeding volume over time, thereby providing an important theoretical basis for engineering.

[0040] like Figure 1 As shown, a method for characterizing the bleeding of fresh cement paste according to the present invention includes the following steps:

[0041] S1. Select the bleeding process of a specific fresh cement paste as the research object, and conduct experiments to obtain experimental data on the change of the amount of fresh cement paste bleeding over time within the observation period.

[0042] The experimental data show the characteristics of the increase in the amount of water bleeding from fresh cement paste over time.

[0043] S2. Establish a time-dependent self-weight consolidation model to characterize the bleeding of fresh cement paste, and derive the analytical solution of the model; further integrate the analytical solution of the model to obtain the bleeding amount and bleeding rate of the cement paste.

[0044] The time-dependent self-weight consolidation model is as follows:

[0045] ;

[0046] in, For cement paste at high and time Porosity below For time, For height, h is the total height of the cement paste. As a time scale factor, Let be the bleeding coefficient. Based on the fundamental properties of partial differential equations, the analytical solution of the time-dependent self-weight consolidation model is derived as follows:

[0047] ;

[0048] Where A represents the cement paste parameters, which are obtained directly through fitting. The initial porosity, For the terms of the summation of the series, .

[0049] Bleeding of cement paste It can be represented as:

[0050] ;

[0051] Correspondingly, the rate of water seepage for:

[0052] ;

[0053] S3. Combine the experimental data to obtain the parameters of the time-dependent self-weight consolidation model in step S2;

[0054] Specifically: Based on experimental data, the parameters of the time-dependent self-weight consolidation model in step S2 were fitted using the nonlinear least squares method: cement paste parameters. Perfusion coefficient Time scale factor .

[0055] S4. Based on the model parameters obtained from the fitting, simulate the change curve of the bleeding amount of fresh cement paste.

[0056] The system of the present invention includes: The data acquisition unit selected the bleeding process of fresh cement paste as the research object and conducted experiments to obtain scatter plot test data on the change of the amount of cement paste sample bleeding over time within the observation period. The model building unit is used to establish a time-dependent self-weight consolidation model characterizing the bleeding of fresh cement paste and derive the analytical solution of the model; the bleeding amount and bleeding rate of the cement paste are obtained by further integration based on the analytical solution of the model. The parameter fitting unit is used to combine the experimental data of the bleeding amount of cement paste sample with time in the data acquisition unit to fit the parameters of the time-dependent self-weight consolidation model in the model construction unit. The variation curve acquisition unit is used to simulate the variation curve of cement paste bleeding based on the model parameters obtained by fitting.

[0057] The present invention also provides an electronic device, including a memory, a processor, and a computer program / instructions stored in the memory and executable on the processor, wherein the computer program / instructions, when executed by the processor, implement the steps of the method for characterizing the bleeding of fresh cement paste.

[0058] The present invention also provides a computer-readable storage medium storing computer instructions, which, when invoked, are used to perform the steps of the method for characterizing the bleeding of fresh cement paste.

[0059] The present invention also provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the method for characterizing the bleeding of fresh cement paste.

[0060] Example verification:

[0061] Please see Figure 1 , Figure 2 , Figure 3 As shown, the method for characterizing the bleeding of fresh cement paste according to the present invention is specifically operated as follows:

[0062] (1) The specific experiment was conducted by using two sets of experiments in the literature, one with sulfoaluminate cement and the other with silicate cement as the main cementitious materials, to extract experimental data on the change of bleeding water in fresh cement paste over time. For details, see the literature Y. Vanhove, KH Khayat, Forced bleeding test to assess stability of flowable concrete, ACI Mater. J. 113(M69) (2016) 753-758 and the literature I. Yakoubi, S. Aggoun, HA Aider, H. Houari, The influence of bleeding, extra water and superplasticizer on the SCC plastic shrinkage cracking: case of hot weather, J. Adhes. Sci. Technol. 30(23) (2016) 2596-2618.

[0063] (2) The variation law of fresh cement paste bleeding volume with time in the embodiment was fitted using the bleeding volume and bleeding rate expressions derived from the time-dependent self-weight consolidation model proposed in this invention to fit the experimental data in step (1). At the same time, in order to verify the feasibility of the model of this invention, the characterization results of the traditional self-weight consolidation model were compared with those of the model of this invention. See Figure 2 and Figure 3 The results show that traditional self-weight consolidation models cannot effectively characterize the change process of cement paste bleeding, while the model of this invention has a high degree of agreement with the experimental data and has a significant fitting advantage. The parameters and goodness of fit of the model of this invention calculated by nonlinear least squares method are shown in Table 1, and Table 1 shows the feasibility of this characterization method.

[0064] Table 1. Parameters and goodness of fit of the time-dependent self-weight consolidation model for the bleeding process of cement paste.

[0065]

[0066] This invention focuses on the bleeding process of fresh cement paste. It obtains experimental data on the change in bleeding volume over time at different moments, then establishes a time-dependent self-weight consolidation model, derives an analytical solution, and, combined with the experimental data, determines the parameters of the time-dependent self-weight consolidation model. This quantifies the bleeding curve of fresh cement paste and simulates the changing patterns of the bleeding process. The method of this invention employs a power-law dependent bleeding coefficient, which has a clear analytical solution, is easy to calculate, and has high simulation accuracy. It has a wide range of engineering applications and can provide an effective theoretical tool for characterizing the bleeding process of fresh cement paste.

Claims

1. A method for characterizing the bleeding water of fresh cement paste, characterized in that, Includes the following steps: The bleeding process of fresh cement paste was selected as the research object, and scattered experimental data of the change of the bleeding amount of fresh cement paste over time were obtained during the observation period. A time-dependent self-weight consolidation model characterizing the bleeding of fresh cement paste was established, and the analytical solution of the model was derived. Based on the analytical solution of the model, the bleeding amount and bleeding rate of the cement paste were obtained by further integration. The parameters of the time-dependent self-weight consolidation model were obtained by fitting the experimental data. Based on the model parameters obtained from the fitting, the variation curve of the bleeding amount of fresh cement paste was simulated.

2. The method according to claim 1, characterized in that, The experimental data show the characteristics of the increase in the amount of bleeding water in fresh cement paste over time during the observation period.

3. The method according to claim 1, characterized in that, A time-dependent self-weight consolidation model characterizing the bleeding of fresh cement paste was established, and the analytical solution of the model was derived; including: The time-dependent self-weight consolidation model is as follows: ； in, For cement paste at high and time Porosity below For time, For height, h is the total height of the cement paste. As a time scale factor, Let be the bleeding coefficient; based on the fundamental properties of partial differential equations, the analytical solution of the time-dependent self-weight consolidation model is derived as follows: ； in, These are parameters of the cement paste, obtained directly through fitting. The initial porosity, For the terms in the summation of the series.

4. The method according to claim 1, characterized in that, The amount and rate of water leakage are obtained from the analytical solution of the model; including: Bleeding of cement paste Represented as: ； in, For cement paste parameters, This represents the total height of the cement paste. For the terms of the summation of the series, The permeability coefficient, For time, For time scale factors; Perfusion rate for: 。 5. The method according to claim 1, characterized in that, The parameters of the time-dependent self-weight consolidation model were fitted using the nonlinear least squares method. These parameters included: cement paste parameters. , water secretion coefficient and time scale factor .

6. The method according to claim 1, characterized in that, Based on the obtained model parameters, a curve simulating the change in the amount of fresh cement paste bleeding over time was generated.

7. A system for characterizing the bleeding water of fresh cement paste, characterized in that, include: The data acquisition unit selected the bleeding process of fresh cement paste as the research object and conducted experiments to obtain scatter plot test data on the change of the amount of cement paste sample bleeding over time within the observation period. The model building unit is used to establish a time-dependent self-weight consolidation model characterizing the bleeding of fresh cement paste and derive the analytical solution of the model; the bleeding amount and bleeding rate of the cement paste are further obtained by integrating the analytical solution of the model. The parameter fitting unit is used to combine the experimental data of the bleeding amount of cement paste sample with time in the data acquisition unit to fit the parameters of the time-dependent self-weight consolidation model in the model construction unit. The variation curve acquisition unit is used to simulate the variation curve of cement paste bleeding based on the model parameters obtained by fitting.

8. An electronic device, comprising a memory, a processor, and a computer program / instructions stored in the memory and executable on the processor, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method for characterizing the bleeding of fresh cement paste as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when invoked, are used to perform the steps of the method for characterizing the bleeding of fresh cement paste as described in any one of claims 1-6.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method for characterizing the bleeding of fresh cement paste as described in any one of claims 1-6.

Images