Method and system for measuring the performance of polycarboxylic acid-based water reducing agents in concrete systems

Abstract

The present invention relates to a method and system for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system. [Solution] The present invention establishes an interface model based on the calcium silicate hydrate gel (CSH) model and the molecular dynamics model of polycarboxylic acid water reducer, which can cover the complexity of the cement particle interface and the variability of polycarboxylic acid water reducer, and further establishes the link between the microstructure of polycarboxylic acid water reducer and the macrofluidity of cement across multiple scales. Based on the established interface model, the friction resistance can be accurately calculated to accurately test the performance of polycarboxylic acid water reducer, shorten the screening cycle of polycarboxylic acid water reducer, and improve the efficiency of performance optimization. In addition, the present invention reveals the specific action process of polycarboxylic acid water reducer in cement on a microscale, which helps to understand the mechanism of the effect of polycarboxylic acid water reducer on the performance of cement, thereby providing theoretical support for the molecular structure design and optimization of polycarboxylic acid water reducer, and can also guide the testing, research and development or finished product manufacturing process of polycarboxylic acid water reducer.

Description

[Technical field]

[0001] This application claims priority to a Chinese patent application filed with the China Patent Office on January 24, 2022, bearing application number CN202210078952.X and entitled "Method and system for measuring the performance of polycarboxylic acid-based water reducer in concrete system", the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the technical fields of concrete performance evaluation and concrete admixtures, and in particular to a method and system for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system. [Background technology]

[0003] In recent years, with the rapid development of concrete technology, water-reducing agent products have also been continuously and repeatedly updated and replaced. The third generation of high-efficiency water-reducing agents, represented by polycarboxylic acid water-reducing agents, have many excellent properties and excellent comprehensive performance, which greatly improve the workability of fresh concrete and are widely used in the preparation of high-strength concrete. Polycarboxylic acid water-reducing agents are important admixtures in modern concrete technology. As a high-efficiency water-reducing agent in the cement industry, its main function is to reduce the water-cement ratio and control the hardening time under the premise of not losing fluidity. At present, polycarboxylic acid water-reducing agents are the only high-efficiency water-reducing agents that can maintain good fluidity of concrete even after the water-binder ratio reaches 2.0, and polycarboxylic acid water-reducing agents are water-reducing agents that can maintain the fluidity of concrete for a longer period of time compared with traditional naphthalene sulfonates. Therefore, polycarboxylic acid water-reducing agents are widely applied in high-performance concrete materials such as self-compacting concrete and ultra-high performance concrete.

[0004] In the prior art, there are several experimental studies on the fluidity of concrete mixed with polycarboxylic acid water reducers, and these traditional research methods include slump test, VeBe consistency test, jumping table test, remolding test, and deformation test. However, in the traditional experimental methods, the polycarboxylic acid water reducer molecules must be obtained first, and the performance of the polycarboxylic acid water reducer cannot be measured in advance to obtain the polycarboxylic acid water reducer molecules. In addition, these measurement methods have a long experimental time, complicated experimental procedures, and a long performance evaluation period for the polycarboxylic acid water reducer, which is disadvantageous to efficient design. Summary of the Invention [Problem to be solved by the invention]

[0005] To solve the above-mentioned problems in the prior art, the present invention provides a method and system for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system. [Means for solving the problem]

[0006] To achieve the above objectives, the present invention provides the following technical solutions: A method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, comprising: Construct an interface model of a cement paste based on a calcium silicate hydrate gel (CSH) model and a polycarboxylic acid-based water reducer model; set a first end of the calcium silicate hydrate gel (CSH) model in the interface model as a first rigid body, and set a second end of the calcium silicate hydrate gel (CSH) model in the interface model as a second rigid body; Setting molecular dynamics simulation parameters; the molecular dynamics simulation parameters include a temperature, a time step, and a rigid body thickness; The molecular dynamics simulation parameters are assigned to the interface model, and then a simulation is performed according to a first predetermined condition to obtain an interface model of the cement paste under standard atmospheric pressure; The molecular dynamics simulation parameters are applied to an interface model of the cement paste under standard atmospheric pressure, and then simulation is performed based on a second predetermined condition to obtain a coordinate position on the x-axis of a spatial coordinate system of a first side atom of the second rigid body; the spatial coordinate system has an origin at a boundary point at one end of the bottom of the second rigid body; calculating a spring force based on the coordinate position and a predetermined coefficient, and determining an interfacial friction force based on the spring force; determining the performance of the polycarboxylic acid water reducer in the concrete based on the interfacial friction. Each step is executed by a computer. .

[0007] Preferably, constructing an interface model of a cement paste based on the calcium silicate hydrate gel (CSH) model and the polycarboxylic acid-based water reducing agent model specifically includes: Perform supercell on the structural analogue of CSH gel to obtain a calcium silicate hydrate gel (CSH) model; remove the intermediate silicon chain layer of the calcium silicate hydrate gel (CSH) model to obtain a calcium silicate hydrate gel (CSH) model with intermediate defect spaces; This involves fitting a molecular dynamics model of a polycarboxylic acid-based water reducer and a water molecule model into the intermediate defect space of the calcium silicate hydrate gel (CSH) model. Each step is executed by a computer. .

[0008] Preferably, the step of providing the molecular dynamics simulation parameters to the interface model and then simulating the interface model of the cement paste under standard atmospheric pressure based on a first predetermined condition includes the steps of: imparting the molecular dynamics simulation parameters to the interface model to obtain a first interface model; and fixing a second rigid body of the first interface model along a z-axis of the spatial coordinate system and applying a constant normal load of a predetermined value to a first rigid body of the first interface model to simulate an interface model of the cement paste under standard atmospheric pressure. Each step is executed by a computer. .

[0009] Preferably, the molecular dynamics simulation parameters are applied to the interface model of the cement paste under standard atmospheric pressure, and then the simulation is performed according to a second predetermined condition to obtain the coordinate position of the first side atom in the second rigid body on the x-axis of the spatial coordinate system, specifically: The molecular dynamics simulation parameters are applied to an interface model of the cement paste under standard atmospheric pressure to obtain a second interface model; and moving a first rigid body of the second interface model along the x-axis of the spatial coordinate system at a predetermined speed, simulating a shear movement process between cement particles using a second rigid body of the second interface model and a spring, and recording a coordinate position on the x-axis of the spatial coordinate system of a first side atom of the second rigid body during the shear movement process. Each step is executed by a computer. .

[0010] Preferably, the calcium silicate hydrate gel (CSH) model has a size of 33.48 Å×29.56 Å×91.08 Å.

[0011] Preferably, the polycarboxylic acid-based water reducing agent is any one of a methoxypolyethylene glycol monomethyl ether-based polycarboxylic acid-based water reducing agent, a polyethylene glycol monomethyl allyl ether-based polycarboxylic acid-based water reducing agent, an isobutylene alcohol polyoxyethylene ether-based polycarboxylate water reducing agent, a 4-hydroxybutyl vinyl ether-based polycarboxylic acid-based water reducing agent, and a propyl polyoxyethylene ether-type polycarboxylic acid-based water reducing agent.

[0012] Preferably, the size of the intermediate defect space of the calcium silicate hydrate gel (CSH) model having the intermediate defect space is 30 Å to 50 Å. Effect of the Invention

[0013] According to the specific embodiments provided according to the present invention, the present invention discloses the following technical effects: The method for measuring the performance of polycarboxylic acid water reducer in concrete system provided according to the present invention constructs an interface model based on calcium silicate hydrate gel (CSH) model and polycarboxylic acid water reducer molecular dynamics model, which can cover the complexity of cement particle interface and the variability of polycarboxylic acid water reducer, and further establishes the link between the microstructure of polycarboxylic acid water reducer and the macrofluidity of cement across multiple scales. In addition, based on the constructed interface model, the friction resistance can be accurately calculated to accurately test the performance of polycarboxylic acid water reducer, shorten the screening cycle of polycarboxylic acid water reducer, and improve the efficiency of performance optimization. In addition, the present invention reveals the specific action process of polycarboxylic acid water reducer in cement on a microscale, which helps to understand the mechanism of the effect of polycarboxylic acid water reducer on the performance of cement, thereby providing theoretical support for the molecular structure design and optimization of polycarboxylic acid water reducer, and at the same time guiding the testing, research and development or finished product manufacturing process of polycarboxylic acid water reducer.

[0014] Corresponding to the above-mentioned method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, the present invention also provides a system for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, the system comprising: an interface model construction module used to construct an interface model of the cement paste based on a calcium silicate hydrate gel (CSH) model and a polycarboxylic acid-based water reducer model, wherein a first end of the calcium silicate hydrate gel (CSH) model in the interface model is set to a first rigid body, and a second end of the calcium silicate hydrate gel (CSH) model in the interface model is set to a second rigid body; a simulation parameter setting module used to set molecular dynamics simulation parameters including temperature, time step, and rigid body thickness; a simulation module for performing a simulation based on a first predetermined condition after the molecular dynamics simulation parameters are assigned to the interface model to obtain an interface model of the cement paste under standard atmospheric pressure; and; a coordinate position determination module for performing a simulation based on a second predetermined condition after the molecular dynamics simulation parameters are applied to an interface model of a cement paste under standard atmospheric pressure, and obtaining coordinate positions of the first side atoms in the second rigid body on the x-axis of a spatial coordinate system having a boundary point at one end of the bottom of the second rigid body as an origin. and ; The coordinate position and calculating a spring force based on a predetermined coefficient, An interface friction determination module used to determine the interface friction force based on and ; A performance determination module is included for determining the performance of the polycarboxylic acid water reducer in concrete based on the interfacial friction.

[0015] The technical effects achieved by the performance measurement system for polycarboxylic acid-based water-reducing agents in concrete systems provided by the present invention are the same as those achieved by the above-mentioned method for measuring the performance of polycarboxylic acid-based water-reducing agents in concrete systems, and therefore will not be repeated here. [Brief description of the drawings]

[0016] In order to more clearly describe the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings in the following description are only part of the present invention, and for the embodiments, those skilled in the art can also obtain other drawings based on these drawings without creative efforts. [Figure 1] 1 is a flow chart of a method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system provided according to the present invention; [Diagram 2] 1 is a schematic diagram of an interface model provided according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a schematic diagram of a first molecular simulation process provided according to an embodiment of the present invention; [Figure 4] FIG. 2 is a schematic diagram of a second molecular simulation process provided according to an embodiment of the present invention; [Diagram 5] FIG. 2 is a chemical structure diagram of a methoxypolyethylene glycol monomethyl ether-based polycarboxylic acid-based water reducer monomer provided according to an embodiment of the present invention; [Figure 6] 1 is a test chart of interface friction provided according to an embodiment of the present invention; [Figure 7] 1 is a test chart of an average interfacial friction force provided according to an embodiment of the present invention; [Figure 8] FIG. 1 is a schematic diagram of a system configuration for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system provided according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The following clearly and completely describes the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention, but obviously, the described embodiments are only a part, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0018] The present invention aims to provide a method and system for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, which can accurately reflect the effect of a polycarboxylic acid-based water-reducing agent on the fluidity of concrete, accurately evaluate the performance of the polycarboxylic acid-based water-reducing agent, shorten the screening cycle of the polycarboxylic acid-based water-reducing agent, and improve the efficiency of performance optimization.

[0019] In order to make the above-mentioned objectives, features and advantages of the present invention more clear and understandable, the present invention will be described in more detail below in conjunction with drawings and specific embodiments.

[0020] As shown in FIG. 1, the method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system provided by the present invention is as follows: Step 100: Build an interface model of cement paste based on the calcium silicate hydrate gel (CSH) model and the polycarboxylic acid water-reducing agent model. As shown in Figure 2, the interface model includes a calcium silicate hydrate gel (CSH) model with intermediate defect space, and a molecular dynamics model of the polycarboxylic acid water-reducing agent and a water molecule model fitted into the intermediate defect space of the calcium silicate hydrate gel (CSH) model. For example, the present invention selects 11 Å tobermorite as the structural analogue of CSH gel, and the unit cell of 11 Å tobermorite is supercelled along axes a, b, and c to obtain a calcium silicate hydrate gel (CSH) model. As a specific embodiment of the present invention, the size of the calcium silicate hydrate gel (CSH) model may be specifically 33.48 Å×29.56 Å×91.08 Å. The calcium silicate hydrate gel (CSH) model of this size has a suitable size, is easy to modify, and can be easily filled with polycarboxylic acid water reducer and water molecules, which can better simulate the interface of cement particles and help form a more accurate interface model.

[0021] In one embodiment of the present invention, the calcium silicate hydrate gel (CSH) model with intermediate defect space in step 100 can be constructed according to the following method: make the structural analogue of CSH gel into a supercell to obtain a calcium silicate hydrate gel (CSH) model; remove the intermediate silicon chain layer of the calcium silicate hydrate gel (CSH) model to obtain a calcium silicate hydrate gel (CSH) model with intermediate defect space. In the present invention, removing the intermediate silicon chain layer preferably includes removing four layers of silicon chains located in the middle of the space of the calcium silicate hydrate gel (CSH) model, and Ca atoms and water molecules that have chemical coordination relationships with each silicon chain.

[0022] In a specific embodiment of the present invention, the present invention preferably further comprises removing the bottom silicon chain layer and the top silicon chain layer of the calcium silicate hydrate gel (CSH) model having an intermediate defect space. In the present invention, removing the bottom silicon chain layer preferably comprises removing one silicon chain layer located at the bottom of the calcium silicate hydrate gel (CSH) model space, and Ca atoms and water molecules that have a chemical coordination relationship with each silicon chain. In the present invention, removing the top silicon chain layer preferably comprises removing one silicon chain layer located at the top of the calcium silicate hydrate gel (CSH) model space, and Ca atoms and water molecules that have a chemical coordination relationship with each silicon chain.

[0023] The interface model of step 100 is obtained based on carrying out the following method: fitting a polycarboxylic acid-based water-reducing agent molecular dynamics model and a water molecule model into the intermediate defect space of the calcium silicate hydrate gel (CSH) model.

[0024] In the embodiment of the present invention, the molecular dynamics model of the polycarboxylic acid-based water reducer is prepared by drawing the molecular structure of the polycarboxylic acid-based water reducer monomer based on the chemical structure of the polycarboxylic acid-based water reducer monomer, polymerizing and constructing the polycarboxylic acid-based water reducer monomer molecule to obtain the molecular structure of the polycarboxylic acid-based water reducer, and then using the ForciteTools module of the MaterialsStudios software to perform molecular dynamics optimization on the molecular structure of the polycarboxylic acid-based water reducer to obtain the molecular dynamics model of the polycarboxylic acid-based water reducer.

[0025] In an embodiment of the present invention, the polycarboxylic acid-based water reducer is any one of a methoxypolyethylene glycol monomethyl ether-based polycarboxylic acid-based water reducer (MPEG-PCE) molecular dynamics model (as shown in FIG. 5), a methylallyl alcohol polyoxyethylene ether-based polycarboxylic acid-based water reducer (TPEG-PCE) molecular dynamics model, an isobutenol alcohol polyoxyethylene ether-based polycarboxylate water reducer (HPEG-PCE) molecular dynamics model, a 4-hydroxybutyl vinyl ether-based polycarboxylic acid ethylene-based polycarboxylic acid-based water reducer (VPEG-PCE) molecular dynamics model, and a propyl polyoxyethylene ether-type polycarboxylic acid-based water reducer (APEG-PCE) molecular dynamics model.

[0026] In an embodiment of the present invention, the number of molecules of the carboxylic acid-based water reducer in the polycarboxylic acid-based water reducer molecular dynamics model is adapted to the size of the intermediate defect space of the calcium silicate hydrate gel (CSH) model having the intermediate defect space.

[0027] In this embodiment of the present invention, there are no special requirements regarding the method of constructing the water molecule model.

[0028] In an embodiment of the present invention, the fitting number of the water molecule model is determined based on the water content of the formed interface model.

[0029] In the embodiment of the present invention, the size of the intermediate defect space of the calcium silicate hydrate gel (CSH) model is 30 Å to 50 Å. Controlling the defect size is favorable for filling the molecular dynamics model of the polycarboxylic acid water-reducing agent and the water molecule model, and for accurately simulating the situation of the polycarboxylic acid water-reducing agent at the interface between cement particles.

[0030] Step 101: Set the molecular dynamics simulation parameters. The molecular dynamics simulation parameters include temperature, time step, and rigid body thickness. For example, the temperature is set to 298K, the temperature control method is selected as the Berendsen method, the time step is set to 1fs, the top of the calcium silicate hydrate gel (CSH) model of the interface model is set to the first rigid body, the bottom of the calcium silicate hydrate gel (CSH) model of the interface model is set to the second rigid body, and the thicknesses of the first and second rigid bodies are set to 4.6 Å.

[0031] Step 102: After the molecular dynamics simulation parameters are assigned to the interface model, a simulation is performed according to a first predetermined condition to obtain an interface model of the cement paste under standard atmospheric pressure. For example, after the molecular dynamics simulation parameters are assigned to the interface model, the second rigid body is fixed along the z-axis direction, and the first rigid body is subjected to a constant normal load of 1 atm along the negative direction of the z-axis (as shown in FIG. 3), and the normal load acts uniformly on the surface of the first rigid body to simulate the state of the cement paste under standard atmospheric pressure. The process is mainly based on the LAMPPS software to perform molecular dynamics simulation on the interface model. The present invention can use various methods to perform molecular dynamics simulation on the interface model, and preferably uses the LAMPPS software to perform molecular dynamics simulation on the interface model, which has a high simulation degree, high calculation efficiency, and accurate and reliable results.

[0032] Step 103: After the molecular dynamics simulation parameters are assigned to the interface model of the cement paste under standard atmospheric pressure, a simulation is performed based on a second predetermined condition to obtain the coordinate position on the x-axis of the spatial coordinate system of the first side atom in the second rigid body. The spatial coordinate system has the boundary point of the bottom front end of the second rigid body as its origin. For example, after the molecular dynamics simulation parameters are assigned to the interface model of the cement paste under standard atmospheric pressure, the first rigid body is set to a constant speed along the positive direction of the x-axis, other parts of the calcium silicate hydrate gel (CSH) model are free to move, and the second rigid body is connected to a fixed spring with a stiffness coefficient of 0.001 N / m (as shown in FIG. 4), and the shear motion process between the cement particles is simulated, and the coordinate position in the x-axis direction of the leftmost atom of the lower rigid body during the shear motion process is recorded. Here, when performing the molecular simulation, the constant speed is set to 1 m / s. In the present invention, when performing molecular simulation, the constant speed is set to 1m / s, and the motion of each part of the lower part is driven by the motion of the upper rigid body, so as to more realistically simulate the relative motion between cement particles in the cement paste, and improve the accuracy and precision of the simulation test. In addition, the spring force is used to characterize the interface friction force, so that the magnitude of the spring force during the shear process can be well calculated. That is, the interface friction force during the shear process can be obtained, and the calculation is simple, accurate, and efficient. In Figures 2 to 4, symbol 1 is the CSH model, symbol 2 is the polycarboxylic acid water reducer, and symbol 3 is the water molecule model.

[0033] Step 104: Determine the interfacial friction force based on the coordinate position. Specifically, the spring force F during the shear process, that is, the friction force between the interfaces, can be calculated based on the coordinate position of the leftmost atom in the x-axis direction, where the calculation formula for F is as follows: [Formula 1] F = -KX (1); [Formula 2] X=X n -X0(2); where K is the stiffness coefficient of the spring and X nis the coordinate position of the leftmost atom in the x-axis direction, and X0 is the initial coordinate position of the leftmost atom in the x-axis direction.

[0034] Step 105: Determine the performance of the polycarboxylic acid-based water-reducing agent in concrete based on the interface friction. Specifically, based on the interface friction force, obtain the interface friction curve in the shear process of the interface model, and compare the magnitude of the interface friction to evaluate the performance of the polycarboxylic acid-based water-reducing agent in concrete. Before obtaining the interface friction curve, the obtained interface friction data can also be processed using Origin software. This data processing method is convenient to operate, highly efficient, has accurate processing results, and is convenient to use.

[0035] An example of the embodiment is provided below to describe the specific implementation process of the above-mentioned method for measuring the performance of polycarboxylic acid-based water-reducing agent in concrete system. In practical application, the parameters in the following embodiment do not specifically limit the technical solution of the present invention provided above.

[0036] 1) First, export the 11 Å tobermorite unit cell from the structural database of the MaterialsStudios simulation software, and make the tobermorite unit cell into a 4-fold, 3-fold and 2-fold supercell along the axes a, b and c, respectively, to obtain a model with a = 33.48 Å, b = 29.56 Å, c = 91.08 Å, that is, the CSH model. According to the chemical structure of the methoxypolyethyleneglycolmonomethylether-based polycarboxylic acid water reducer (MPEG-PCE) monomer, draw the monomer molecular structure of the methoxypolyethyleneglycolmonomethylether-based polycarboxylic acid water reducer, polymerize the four methoxypolyethyleneglycolmonomethylether-based polycarboxylic acid water reducer monomer molecular structures, and perform dynamic optimization to obtain the methoxypolyethyleneglycolmonomethylether-based polycarboxylic acid water reducer molecular dynamics model. Create one water molecule model based on the water molecule formula.

[0037] 2) Remove one layer of silicon chains at the top and bottom of the CSH model, and the nearby Ca atoms and water molecules, respectively, then remove four layers of silicon chains and the nearby Ca atoms and water molecules in the middle, so that defects are formed in the middle of the CSH model. By modifying the surface Ca of the model, two methoxypolyethylene glycol monomethyl ether-based polycarboxylic acid-based water reducer models and water molecule models with the numbers of 100, 200, and 300, respectively, are filled into the defects to construct an interface model.

[0038] 3) Set the molecular dynamics simulation parameters: select the canonical ensemble as the simulation ensemble, set the temperature to 298 K, select the Berendsen method as the temperature control method, set the time step to 1 fs, and set the upper part of the top CSH model and the lower part of the bottom CSH model of the interface model to rigid bodies with a thickness of 4.6 Å, respectively.

[0039] 4) The simulation parameters set in step 3) were assigned to each component of the interface model in step 2), the lower rigid body was fixed along the z-axis direction, and a constant normal load of 1 atm was applied to the upper rigid body along the negative direction of the z-axis. The normal load was applied uniformly to the surface of the upper rigid body to simulate the state of the cement paste under standard atmospheric pressure, and the simulation time was set to 1 ns.

[0040] 5) The simulation parameters set in step 3) were assigned to each component of the interface model obtained in the final simulation in step 4), the upper rigid body was set to a constant speed along the positive direction of the x-axis, the other parts of the CSH model were free to move, and the lower rigid body was connected to a fixed spring with a stiffness coefficient of 0.001 N / m to simulate the shear movement process between cement particles, and the coordinate position in the x-axis direction of the leftmost atom of the lower rigid body during the shear movement process was recorded, and the simulation time was set to 2 ns.

[0041] 6) The spring force F during the shear process, i.e., the friction force between the interfaces, can be calculated from the coordinate position of the leftmost atom in the x-axis direction, where F is calculated using the above equations (1) and (2).

[0042] 7) The data obtained in step 6) was processed to obtain the interface friction curve in the shear process of the interface model (as shown in Figure 6), and the performance of the polycarboxylic acid-based water reducer in concrete was evaluated by comparing the magnitude of the interface friction (as shown in Figure 7).

[0043] Based on the above description, the method for measuring the performance of polycarboxylic acid water-reducing agent in concrete system provided by the present invention is a simulation test and evaluation method for the performance of polycarboxylic acid water-reducing agent in concrete system using computer simulation technology, which is a method based on molecular dynamics simulation design, and the interface model constructed based on the technical solution of the present invention can cover the complexity of cement particle interface and the variability of polycarboxylic acid water-reducing agent, and further establish the link between the microstructure of polycarboxylic acid water-reducing agent and the macro-fluidity of cement across multiple scales. Accurately calculating the friction resistance of the interface can further be applied to the performance evaluation of polycarboxylic acid water-reducing agent. The present invention clarifies the action process of polycarboxylic acid water-reducing agent in cement on a micro-scale, and helps to understand the mechanism of the effect of polycarboxylic acid water-reducing agent on the performance of cement, thereby providing theoretical support for the molecular structure design and optimization of polycarboxylic acid water-reducing agent, and at the same time guiding the testing, research and development or finished product manufacturing process of polycarboxylic acid water-reducing agent.

[0044] In addition, corresponding to the performance measurement method of polycarboxylic acid-based water-reducing agent in concrete system provided above, the present invention also provides a performance measurement system of polycarboxylic acid-based water-reducing agent in concrete system, as shown in FIG. 8, the system includes an interface model construction module 800, a simulation parameter setting module 801, a simulation module 802, a coordinate position determination module 803, an interface friction force determination module 804, and a performance determination module 805.

[0045] Here, the interface model construction module 800 is used to construct an interface model of cement paste based on a calcium silicate hydrate gel (CSH) model and a polycarboxylic acid-based water reducer model.

[0046] The simulation parameter setting module 801 is used to set molecular dynamics simulation parameters, including temperature, time step, and rigid body thickness.

[0047] The simulation module 802 is used to impart molecular dynamics simulation parameters to the interface model, and then perform simulation based on a first predetermined condition to obtain an interface model of the cement paste under standard atmospheric pressure.

[0048] The coordinate position determination module 803 is used to obtain the coordinate position of the first side atom of the second rigid body on the x-axis of the spatial coordinate system by simulating the interface model of the cement paste under standard atmospheric pressure based on the molecular dynamics simulation parameters according to the second predetermined condition, the spatial coordinate system having the boundary point of the bottom end of the second rigid body as the origin.

[0049] The interface friction force determination module 804 is used to determine the interface friction force based on the coordinate position.

[0050] The performance determination module 805 is used to determine the performance of the polycarboxylic acid water reducer in concrete based on the interfacial friction.

[0051] Each embodiment in this specification is described step by step, and in each embodiment, the focus of the description is the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for related information, please refer to the description of the method part.

[0052] In this specification, the principle and implementation of the present invention are described using specific examples, but the description of the above embodiments is intended to help understand the method of the present invention and its core idea; at the same time, those skilled in the art will have changes in the specific implementation and scope of use based on the idea of ​​the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, comprising: constructing an interface model of a cement paste based on a calcium silicate hydrate gel (C-S-H) model and a polycarboxylic acid-based water reducing agent model; setting a first end of the calcium silicate hydrate gel (C-S-H) model in the interface model as a first rigid body, and setting a second end of the calcium silicate hydrate gel (C-S-H) model in the interface model as a second rigid body; Setting molecular dynamics simulation parameters; the molecular dynamics simulation parameters include a temperature, a time step, and a rigid body thickness; After the molecular dynamics simulation parameters are assigned to the interface model, a simulation is performed based on a first predetermined condition to obtain an interface model of the cement paste under standard atmospheric pressure; The molecular dynamics simulation parameters are applied to an interface model of the cement paste under standard atmospheric pressure, and then a simulation is performed based on a second predetermined condition to obtain a coordinate position on the x-axis of a spatial coordinate system of a first side atom of a second rigid body; the spatial coordinate system has an origin at a boundary point at one end of a bottom of the second rigid body; calculating a spring force based on the coordinate position and a predetermined coefficient, and determining an interface friction force based on the spring force; A method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, comprising: causing a computer to execute each step, including determining the performance of the polycarboxylic acid-based water-reducing agent in the concrete system based on the interfacial friction.

2. Specifically, constructing an interface model of a cement paste based on the calcium silicate hydrate gel (CSH) model and the polycarboxylic acid-based water-reducing agent model includes the following steps: Perform supercell on the structural analogue of C-S-H gel to obtain a calcium silicate hydrate gel (C-S-H) model; remove the intermediate silicon chain layer of the calcium silicate hydrate gel (C-S-H) model to obtain a calcium silicate hydrate gel (C-S-H) model with intermediate defect spaces; The method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system according to claim 1, characterized in that the steps including fitting a molecular dynamics model of the polycarboxylic acid-based water-reducing agent and a water molecule model into the intermediate defect space of the calcium silicate hydrate gel (CSH) model are executed by a computer.

3. The molecular dynamics simulation parameters are assigned to the interface model, and then the interface model of the cement paste is simulated under a first predetermined condition to obtain the interface model of the cement paste under standard atmospheric pressure, specifically, imparting the molecular dynamics simulation parameters to the interface model to obtain a first interface model; The method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, as described in claim 1, further comprising the step of causing a computer to execute each of the steps, including fixing a second rigid body of the first interface model along the z-axis of the spatial coordinate system and applying a constant normal load of a predetermined value to the first rigid body of the first interface model, in order to simulate an interface model of a cement paste under standard atmospheric pressure.

4. The molecular dynamics simulation parameters are applied to an interface model of a cement paste under standard atmospheric pressure, and then the interface model is simulated based on a second predetermined condition to obtain a coordinate position of a first side atom of a second rigid body on an x-axis of a spatial coordinate system, specifically, The molecular dynamics simulation parameters are applied to an interface model of the cement paste under standard atmospheric pressure to obtain a second interface model; The method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system as described in claim 1, characterized in that the method comprises having a computer execute each of the steps, including: moving a first rigid body of the second interface model at a predetermined speed along the x-axis of the spatial coordinate system; simulating a shear motion process between cement particles using a second rigid body of the second interface model and a spring; and recording the coordinate position on the x-axis of the spatial coordinate system of the first side atom of the second rigid body during the shear motion process.

5. The method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system according to claim 1, characterized in that the size of the calcium silicate hydrate gel (CSH) model is 33.48 Å×29.56 Å×91.08 Å.

6. The method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system according to claim 2, characterized in that the polycarboxylic acid-based water-reducing agent is any one of a methoxypolyethylene glycol monomethyl ether-based polycarboxylic acid-based water-reducing agent, a methylallyl alcohol polyoxyethylene ether-based polycarboxylic acid-based water-reducing agent, an isobutenol alcohol polyoxyethylene ether-based polycarboxylate salt water-reducing agent, a 4-hydroxybutyl vinyl ether-based polycarboxylic acid-based water-reducing agent, and a propyl polyoxyethylene ether-type polycarboxylic acid-based water-reducing agent.

7. 3. The method for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system according to claim 2, wherein the size of the defect space is 30 Å to 50 Å.

8. A system for measuring the performance of a polycarboxylic acid-based water reducing agent in a concrete system, comprising: an interface model construction module, which is used to construct an interface model of the cement paste based on a calcium silicate hydrate gel (C-S-H) model and a polycarboxylic acid-based water reducing agent model, and which sets a first end of the calcium silicate hydrate gel (C-S-H) model in the interface model to a first rigid body and sets a second end of the calcium silicate hydrate gel (C-S-H) model in the interface model to a second rigid body; a simulation parameter setting module used to set molecular dynamics simulation parameters including temperature, time step, and rigid body thickness; a simulation module used for providing the molecular dynamics simulation parameters to the interface model, and then simulating based on a first predetermined condition to obtain an interface model of the cement paste under standard atmospheric pressure; a coordinate position determination module, which is used to provide the molecular dynamics simulation parameters to an interface model of the cement paste under standard atmospheric pressure, and then perform simulation based on a second predetermined condition to obtain the coordinate position of the first side atom in the second rigid body on the x-axis of a spatial coordinate system with the boundary point of one end of the bottom of the second rigid body as the origin; an interface friction determination module used to calculate a spring force based on the coordinate position and a predetermined coefficient, and to determine an interface friction force based on the spring force; A system for measuring the performance of a polycarboxylic acid-based water-reducing agent in a concrete system, comprising a performance evaluation module for determining the performance of the polycarboxylic acid-based water-reducing agent in concrete based on the interfacial friction.

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