Method for determining performance index of silicate cement hydration and analysis equipment

Abstract

The application discloses a method for determining a silicate cement hydration performance index, comprising the following steps: 1) respectively establishing mathematical relational expressions of mineral phase dissolution, hydration product deposition, ion adsorption reaction rate and ion concentration; 2) establishing chemical field control equations of mineral phase dissolution, product deposition, ion diffusion and ion adsorption reaction coupling in the hydration process, and potential field and temperature field control equations; combining corresponding boundary and initial conditions, solving the three groups of control equations, and outputting the results of ion concentration, potential and temperature changes with time and spatial distribution in the whole hydration process; and 3) establishing a hydration heat calculation formula of the whole hydration process of the silicate cement. The application further discloses an analysis device. The method is more in line with the real situation of the silicate cement hydration, more accurately describes the cement hydration process from the essential mechanism, can completely, accurately and truly reflect the silicate cement hydration process, and has important research and popularization significance.

Description

Technical Field

[0001] This invention relates to a method for determining cement indicators, specifically a method and analytical equipment for determining the hydration performance indicators of silicate cement, belonging to the technical field of analytical methods. Background Technology

[0002] Silicate cement, as one of the most important building materials, is widely used in engineering construction. Its hydration process determines the formation of micropores, strength evolution, deformation and cracking of the cement paste, significantly affecting the thermal, mechanical, and durability properties of concrete structures. However, due to the numerous mineral components, the significant differences in the hydration characteristics of each mineral, and the extremely complex interactions and influences, the entire hydration process of cement is difficult to fully grasp, and theoretical models and calculation methods are lacking. Therefore, it is essential to establish theoretical models and calculation methods for the hydration performance indicators of silicate cement.

[0003] Currently, research on the hydration performance of silicate cement mainly relies on experimental methods, which are time-consuming, labor-intensive, inefficient, and costly. Existing models do not establish rate formulas for the dissolution of each mineral phase, product deposition, ion diffusion, and ion adsorption, do not consider the interactions between mineral components and their impact on cement hydration, and lack theoretical calculation methods for mineral phase dissolution rates and product precipitation rates that take into account the effects of multi-component interactions. Consequently, they cannot reveal the mechanism by which increasing the C3S / C3A content ratio expands the peak time difference between the silicon phase reaction and the aluminum phase reaction. Summary of the Invention

[0004] The purpose of this invention is to provide a method for calculating the dissolution rate of mineral phases and the precipitation rate of products that takes into account the effects of multiple components, and to construct a theoretical model of cement hydration based on the interaction of multiple mineral components.

[0005] The present invention is implemented as follows:

[0006] A method for determining the hydration performance indicators of silicate cement includes the following steps:

[0007] 1) Based on the different dissolution characteristics of each mineral component in silicate cement and the different deposition characteristics of each hydration product, and based on the saturation state of ion concentration in the hydration slurry, mathematical relationships between the reaction rates of each mineral phase dissolution, product deposition, and ion adsorption and the ion concentration are established respectively.

[0008] 2) Based on the mathematical relationships between reaction rates and ion concentrations established above, and combined with the diffusion coefficients of each ion in the hydration slurry, establish the chemical field control equations for the coupled effects of mineral phase dissolution, product deposition, ion diffusion, and ion adsorption in the hydration process, as well as the electric potential field and temperature field control equations; and solve the three sets of control equations in combination with the corresponding boundary and initial conditions, outputting the results of the changes in ion concentration, electric potential, and temperature over time and their spatial distribution throughout the entire hydration process.

[0009] 3) Based on the above output of ion concentration, potential and temperature changes over time, calculate the dissolution rate of each mineral phase and the deposition rate of hydration products, and establish calculation formulas for (a) the heat release rate of surface water wetting adsorption and initial hydration of mineral phases, and (b) the heat release rate of chemical reaction between silicon phase and aluminum phase and water. Superimpose the heat release rates of the two processes to establish the hydration heat calculation formula for the whole process of silicate cement hydration.

[0010] The present invention also discloses an analytical device using the above-mentioned method for determining the hydration performance index of silicate cement, which includes an input module, a calculation module, and an output module;

[0011] Input module: Used to input the initial condition parameters of the silicate cement hydration process, including the C3S content, C3A content, C4AF content, C2S content, Ca2SO4·H2O content, water-cement ratio, specific surface area, curing temperature, etc. in the cement;

[0012] Calculation module: Based on the initial and boundary condition parameters, using the chemical field governing equations of the cement hydration process, calculates Ca. 2+ H3SiO4 - Al(OH)4 - OH - SO4 2- The changes in plasma concentration, C3S content, dissolution rates of C3A, C4AF, C2S, and Ca2SO4·H2O, and deposition rates of CSH, CH, AFt, and AFm over time were studied. Based on these reaction rates, the heat release of the initial dissolution, silicon phase, and aluminum phase hydration reactions was calculated separately. The two were then superimposed to obtain the heat release rate of the entire silicate cement hydration process.

[0013] Output module: Used to output the calculated heat of hydration as a function of time.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] 1) Based on the different dissolution characteristics of each mineral phase and the different deposition characteristics of each hydration product in silicate cement, this invention establishes reaction rate calculation formulas for the dissolution of each mineral phase and deposition of the products, which are more consistent with the actual situation of silicate cement hydration.

[0016] 2) This invention establishes reaction rate calculation formulas for mineral phase dissolution, product deposition, ion diffusion, and ion adsorption in the cement hydration process, and couples them into the same governing equation. This enables transient calculation and analysis of the dissolution-deposition-diffusion-adsorption coupling effect in the cement hydration process, and describes the cement hydration process more accurately from the essential mechanism.

[0017] 3) This invention establishes hydration heat calculation formulas for the reaction of silica and aluminum phases with water in cement, respectively. Through superposition analysis, a calculation formula for the hydration heat of the entire hydration process of silicate cement can be obtained.

[0018] 4) This invention can calculate the entire process of cement hydration induction, including the pre-induction, induction, acceleration, deceleration, and stabilization stages, as well as the Ca content in cement slurry under different mineral composition contents, time points, specific surface areas, water-cement ratios, and curing temperatures. 2 + H3SiO4 - Al(OH)4 - OH - SO4 2- The results of changes in ion concentration, electric potential, and temperature over time, as well as their spatial distribution and the changes in heat of hydration over time, can completely, accurately, and truthfully reflect the hydration process of silicate cement, and have important research and promotion significance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the silicate cement hydration process model of the present invention; in the figure, 1 is the hydration paste; 2 is the cement particle; 3 is the gypsum particle; (a) is the hydration paste; (b) is the computational domain of mineral phase dissolution, product deposition, ion diffusion and ion adsorption reaction between two adjacent cement and gypsum particles in the paste;

[0020] Figure 2 A schematic diagram of the cement hydration performance index analysis equipment provided by the present invention.

[0021] Figure 3 A schematic diagram of the calculation process for the method of determining the performance indicators of the entire cement hydration process provided by the present invention;

[0022] Figure 4 The graph shows the change in heat of hydration over time as determined by the method described in Example 1.

[0023] Figure 5 The graph shows the change in heat of hydration over time as determined by the method described in Example 2.

[0024] Figure 6 The graph shows the change in heat of hydration over time as determined by the method described in Example 3.

[0025] Figure 7The graph shows the change in heat of hydration over time as determined by the method described in Example 4.

[0026] Figure 8 The graph shows the change in heat of hydration over time as determined by the method described in Example 5.

[0027] Figure 9 The graph shows the change in heat of hydration over time as determined by the method described in Example 6. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0029] A method for determining the hydration performance indicators of silicate cement, as shown in the appendix. Figure 3 As shown, it includes the following steps:

[0030] 1) Based on the different dissolution characteristics of each mineral component in silicate cement and the different deposition characteristics of each hydration product, and based on the saturation state of ion concentration in the hydration slurry, mathematical relationships between the reaction rates of each mineral phase dissolution, hydration product deposition, and ion adsorption and the ion concentration are established respectively.

[0031] 2) Based on the mathematical relationships between reaction rates and ion concentrations established above, and combined with the diffusion coefficients of each ion in the hydration slurry, establish the chemical field control equations for the coupled effects of mineral phase dissolution, product deposition, ion diffusion, and ion adsorption in the hydration process, as well as the electric potential field and temperature field control equations; and solve the three sets of control equations in combination with the corresponding boundary and initial conditions, outputting the results of the changes in ion concentration, electric potential, and temperature over time and their spatial distribution throughout the entire hydration process.

[0032] 3) Based on the above output of ion concentration, potential and temperature changes over time, calculate the dissolution rate of each mineral phase and the deposition rate of hydration products, and establish calculation formulas for (a) the heat release rate of surface water wetting adsorption and initial hydration of mineral phases, and (b) the heat release rate of chemical reaction between silicon phase and aluminum phase and water. Superimpose the heat release rates of the two processes to establish the hydration heat calculation formula for the whole process of silicate cement hydration.

[0033] For ease of understanding and to better illustrate the technical solution of this invention, the inventors have represented the chemical reaction equations involved in the entire hydration process of silicate cement as follows: Equations 1-9:

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] Ca 2+ +2OH - →Ca(OH)2(7)

[0041]

[0042]

[0043] A further step is:

[0044] In step 1), the mathematical relationships between the dissolution reaction rate of each mineral phase, the deposition reaction rate of hydration products, the ion adsorption rate, and the ion concentration during the entire hydration process are constructed as follows:

[0045] Based on the driving and controlling effect of ion concentration saturation on the reaction rates of dissolution, product deposition, ion diffusion, and ion adsorption of various mineral phases, formulas were established for the dissolution rates of mineral phases such as tricalcium silicate (C3S), tricalcium aluminate (C3A), tetracalcium aluminoferrite (C4AF), dicalcium silicate (C2S), and gypsum (Ca2SO4·H2O). Formulas were also established for the deposition rates of hydration products such as hydrated calcium silicate (CSH), calcium hydroxide (CH), ettringite (AFt), and monosulfide-type hydrated calcium sulfoaluminate (AFm). 2+ ), aluminate ions (Al(OH)4) - ), sulfate ions (SO4) 2- The formula for calculating the adsorption rate of ions undergoing hydration reactions is shown in Equation 10-34 below:

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060] v CH =k CH (β CH -1) (24)

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068] In the formula, the subscript k indicates the type of ion, i.e., Ca 2+ H3SiO4 - Al(OH)4 - OH - SO4 2- ;c k J k D k ,z k ,γ k These represent the concentration, diffusion flux, diffusion coefficient, ion valence number, and ion activity coefficient of different types of ions, respectively. Denotes the Hamiltonian operator, where and These represent divergence and gradient, respectively. This represents the rate of formation of the k-th ion caused by the dissolution of silicate cement; This represents the adsorption rate of the k-th ion; V represents the stoichiometric coefficients of the k-th ion in the Ca2SO4·H2O dissolution reaction, and the deposition reactions of CSH, CH, AFt, and AFm, respectively; gyp ,v CSH ,vCH ,v AFt ,v AFm denoted as Ca2SO4·H2O dissolution rate, CSH, CH, AFt, and AFm deposition rates, respectively; T, ψ, F, and R represent temperature, electric potential, Faraday constant, and ideal gas constant, respectively. Let represent the stoichiometric coefficients of the k-th ion in the dissolution reactions of C3S, C3A, C4AF, and C2S, respectively. The dissolution reaction rates of C3S, C3A, C4AF, and C2S are represented respectively. m gypsum These represent the contents of C3S, C3A, C4AF, C2S, and Ca2SO4·H2O in cement, respectively. k gypsum ,k CSH ,k CH ,k AFt ,k AFm denoted as the reaction rate constants for the dissolution of C3S, C3A, C4AF, C2S, and Ca2SO4·H2O, and the deposition of CSH, CH, AFt, and AFm, respectively. K gypsum ,K CSH ,K CH ,K AFt ,K AFm , respectively, represent the reaction equilibrium constants for the dissolution of C3S, C3A, C4AF, C2S, and Ca2SO4·H2O, and the deposition of CSH, CH, AFt, and AFm; Representing Ca 2+ Al(OH)4 - SO4 2- The adsorption rate constant; These represent the surface areas of cement particles and gypsum particles per unit volume of slurry, respectively.

[0069] A further step is:

[0070] In step 2), the methods for coupling the mineral phase dissolution reaction, product deposition reaction, ion diffusion reaction, and ion adsorption reaction in the hydration process within the same chemical field governing equation include:

[0071] Based on the established formulas for calculating the mineral phase dissolution rate, product deposition rate, and ion adsorption rate, the formulas for calculating the release of Ca during the mineral phase dissolution process are established respectively. 2+ H3SiO4 - Al(OH)4 - OH - SO4 2-The rate formulas for the ion diffusion process, the rate formulas for the consumption of each ion during product deposition, and the rate formulas for the consumption of each ion during ion adsorption are established. Simultaneously, based on the driving effects of ion concentration gradient, ion potential gradient, and chemical activity gradient on the ion diffusion process, diffusion equations for each ion during the hydration process are established. The rate formulas for the release of ions during mineral phase dissolution, the consumption of ions during product deposition, and the consumption of ions during ion adsorption are substituted into the ion diffusion equations and coupled to the same governing equation, as shown in equations 35-37 below.

[0072]

[0073]

[0074]

[0075] A further step is:

[0076] In step 2), the method for constructing the electric potential field includes:

[0077] Based on the electric potential field formed by the non-uniform distribution of electrically dissimilar ions in the hydration slurry and its driving effect on the ion diffusion process, the electric field control equation for the hydration process was established using the Poisson equation, as shown below:

[0078]

[0079] In the formula, F, z k , ε r ε and ε0 are the Faraday constant, ion valence, dielectric constant of water, and vacuum dielectric constant, respectively.

[0080] A further step is:

[0081] In step 2), the method for constructing the temperature field includes:

[0082] Based on the heat conduction process of the slurry, the heat conduction control equations for the temperature field are established, as shown in equations 39-43:

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] In the formula, ρ P , ρ cementC represents the density of the slurry, water, and cement, respectively. P , C cement These represent the specific heat capacities of slurry, water, and cement, respectively; k P , k ads w / c, m gypsum , SSA cement , , respectively, represent the thermal conductivity of the slurry, the heat released by the complete hydration of C3A per unit volume, the surface ion adsorption rate constant, the water-cement ratio, the gypsum content, the heat released by the complete hydration of C3A per unit mass, the specific surface area of ​​the particles, and the surface area of ​​cement particles in the hydrated slurry per unit volume; t represents the hydration time, and T represents the slurry temperature.

[0089] A further step is:

[0090] In step 2), the boundary conditions are applied as follows:

[0091] like Figure 1 As shown, the slurry comes into contact with the indoor air environment at its edge, and its temperature at this boundary is room temperature. Therefore, the boundary condition of the temperature field at r = λ is a Dirichlet boundary condition, as shown below:

[0092] T = T M (44)

[0093] In the formula, T M Let r represent room temperature, r be the spatial location variable in the slurry domain, and λ be the radius of the slurry domain;

[0094] like Figure 1 As shown, the center of the slurry is the center of symmetry, and the partial derivative of the temperature field at this boundary is zero. Therefore, the boundary condition for the temperature field at r = 0 is a Neumann boundary condition, as shown below:

[0095]

[0096] like Figure 1 As shown, the ion concentration at the particle surface is saturated, and the surface is taken as the zero potential point.

[0097] Therefore, the boundary conditions for the chemical field and the electric potential field at r = 0 are Dirichlet boundary conditions, as shown below:

[0098]

[0099] In the formula, Representing Ca 2+ H3SiO4 - Al(OH)4- OH - SO4 2- Saturation concentration of ions.

[0100] like Figure 1 As shown, the right boundary of the ion diffusion domain is the surface of the gypsum particles, and the partial derivatives of the chemical field and the electric potential field at this boundary are zero. Therefore, the boundary conditions for the chemical field and the electric potential field at ξ = L are Neumann boundary conditions, as shown in the following equation; where ξ is the spatial position variable in the ion diffusion domain, and L is the length of the ion diffusion domain;

[0101]

[0102] In the formula, Representing Ca 2+ SO4 2- Saturation concentration of ions.

[0103] A further step is:

[0104] In step 2), the initial conditions are as follows:

[0105] T = T M ,c k =0,ψ=0 (48)

[0106] A further step is:

[0107] To simplify calculations, the governing equations for the temperature, chemical, and electric potential fields are treated dimensionlessly, and dimensionless parameters are set as follows:

[0108]

[0109] In the formula, [L], [t], [T], [ψ], [c1], and [c2] represent dimensionless position coordinates, time coordinates, temperature, electric potential, and ion concentration, respectively; [L], [t], [T], [ψ], [c1], and [c2] represent characteristic length, characteristic time, characteristic temperature, characteristic electric potential, and characteristic ion concentration, respectively.

[0110] A further step is:

[0111] In step 3), the method for constructing the formula for calculating the hydration heat release rate of silicate cement includes the following:

[0112] ① Based on the reasons for heat generation during cement hydration, heat sources are divided into two categories, as detailed below:

[0113] Analyzing the various reactions and effects occurring during the hydration process, the essential reasons for heat release can be summarized as follows: (a) heat generated by surface water wetting and adsorption, and the initial hydration of the mineral phase. (b) The heat generated by the chemical reaction of silicon and aluminum phases with water Both types of heat release involve the entire process of hydration, including the pre-induction phase, induction phase, acceleration phase, deceleration phase, and stabilization phase.

[0114] ② Establish calculation formulas for the exothermic rates of surface moisture wetting and adsorption, initial hydration of mineral phases, and chemical reactions of silicon and aluminum phases with water, respectively. Superimpose the exothermic rates of the two processes to establish a method for determining the heat of hydration of silicate cement throughout the entire hydration process. The specific process is as follows:

[0115] (a) Based on the heat release characteristics of surface moisture wetting and adsorption and initial hydration of mineral phases, a formula for calculating the heat release rate is established as follows:

[0116]

[0117] In the formula, n clinker , These represent the water adsorption energy on the C3S surface, the activation energy of the C3A hydration reaction, the mineral type, and the percentage of C3A surface area, respectively.

[0118] (b) Based on the exothermic reasons of the chemical reactions of silicon and aluminum phases with water, the dissolution rates of C3S and C2S are integrated over the space and time of the slurry to obtain the total consumption of C3S and C2S. This is then multiplied by the total heat released per mole of C3S consumed to obtain the exothermic heat of the silicon phase reaction. Simultaneously, the deposition reaction rates of AFt and AFm are integrated over the space and time of the slurry to obtain the total generation of AFt and AFm. This is then multiplied by the heat release per mole of AFt and AFm generated to obtain the heat release of the aluminum phase reaction. The two are summed to establish the calculation formulas for the exothermic heat of hydration of silicon and aluminum phases, as shown in Equations 51-59:

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128] In the formula, and h represents the heat release rates of the silicon phase and the aluminum phase, respectively. P , , respectively, represent the convective heat transfer coefficient of the slurry, the specific heat capacity of the silicon phase, the specific heat capacity of C3A, the total heat of the C3S hydration reaction, the total heat of the C2S hydration reaction, and the activation energy of the C2S hydration reaction; ξ represents the total heat release per unit mole of C3A hydration reaction to generate AFt, the total heat release per unit mole of C3A hydration reaction to generate AFm, the molar ratio of C3A hydration reaction to generate AFt, and the molar ratio of C3A hydration reaction to generate AFm, respectively; ξ is the spatial position variable in the ion diffusion domain; L is the length of the ion diffusion domain.

[0129] The heat generated by (a) surface water wetting and adsorption, and initial hydration of mineral phases (b) Thermal release from the chemical reaction of silicon and aluminum phases with water By combining these two methods, a method for determining the hydration heat release rate throughout the entire hydration process of silicate cement is established, as shown below:

[0130]

[0131] As attached Figure 2 As shown, this embodiment also provides an analytical device for determining the hydration performance index of silicate cement using the above-mentioned method, which includes an input module, a calculation module, and an output module;

[0132] Input module: Used to input the initial condition parameters of the silicate cement hydration process, including the C3S content, C3A content, C4AF content, C2S content, Ca2SO4·H2O content, water-cement ratio, specific surface area, curing temperature, etc. in the cement;

[0133] Calculation module: Based on the initial and boundary condition parameters, using the chemical field governing equations of the cement hydration process, calculates Ca. 2+ H3SiO4 - Al(OH)4 - OH - SO4 2- The changes in plasma concentration, C3S content, dissolution rates of C3A, C4AF, C2S, and Ca2SO4·H2O, and deposition rates of CSH, CH, AFt, and AFm over time were studied. Based on these reaction rates, the heat release of the initial dissolution, silicon phase, and aluminum phase hydration reactions was calculated separately. The two were then superimposed to obtain the heat release rate of the entire silicate cement hydration process.

[0134] Output module: Used to output the calculated heat of hydration as a function of time.

[0135] To provide a more detailed description of the present invention, several more specific embodiments are described below.

[0136] Example 1

[0137] The method for determining the hydration performance index of silicate cement described in this invention was used to calculate and analyze the hydration heat release rate of cement, with the following conditions and parameters:

[0138] 1) The specific characteristics of the materials and the experimental environment are as follows: The content of each mineral component in the silicate cement is: tricalcium silicate 58.73%, tricalcium aluminate 6.84%, tetracalcium aluminoferrite 10.91%, dicalcium silicate 15.51%, and gypsum 5.42%; the water-cement ratio is 0.48; and the specific surface area of ​​the silicate cement is 1300 m². 2 / kg; ambient temperature is 20℃;

[0139] 2) Based on the dissolution-deposition-diffusion-adsorption coupling equation and the calculation formula of hydration exothermic theory for the hydration process of silicate cement, the relationship between the exothermic rate and time during the entire hydration process of silicate cement was calculated. The calculation process will not be described in detail here. The calculation parameters introduced are shown in Table 1.

[0140] The relationship between the theoretically determined and experimentally measured results of the heat release rate of silicate cement hydration paste calculated using the method described in this embodiment and the hydration time is shown in the figure. Figure 4 The results show that the analytical method described in this invention has high accuracy in determining the heat release rate of the entire hydration process of silicate cement.

[0141] Example 2

[0142] The method for determining the hydration performance index of silicate cement described in this invention was used to calculate and analyze the hydration heat release rate of cement. The calculation method is roughly the same as that in Example 1, and the calculation parameters introduced are shown in Table 1.

[0143] The specific characteristics of the materials and the experimental environment are as follows: the mineral components of the silicate cement are: tricalcium silicate 61.78%, tricalcium aluminate 6.44%, tetracalcium aluminoferrite 9.58%, dicalcium silicate 11.58%, and gypsum 3.05%; the water-cement ratio is 0.41; and the specific surface area of ​​the silicate cement is 1000 m². 2 / kg; ambient temperature is 23℃;

[0144] The relationship between the theoretically determined and experimentally measured results of the heat release rate of silicate cement hydration paste calculated using the method described in this embodiment and the hydration time is shown in the figure. Figure 5 The results show that the analytical method described in this invention has high accuracy in determining the heat release rate of the entire hydration process of silicate cement.

[0145] Example 3

[0146] The method for determining the hydration performance index of silicate cement described in this invention was used to calculate and analyze the hydration heat release rate of cement. The calculation method is roughly the same as that in Example 1, and the calculation parameters introduced are shown in Table 1.

[0147] The specific characteristics of the materials and the experimental environment are as follows: the mineral components of the silicate cement are: tricalcium silicate 60.36%, tricalcium aluminate 8.04%, tetracalcium aluminoferrite 8.35%, dicalcium silicate 11.38%, and gypsum 3.33%; the water-cement ratio is 0.5; and the specific surface area of ​​the silicate cement is 1000 m². 2 / kg; ambient temperature is 20℃;

[0148] The relationship between the theoretically determined and experimentally measured results of the heat release rate of silicate cement hydration paste calculated using the method described in this embodiment and the hydration time is shown in the figure. Figure 6 The results show that the analytical method described in this invention has high accuracy in determining the heat release rate of the entire hydration process of silicate cement.

[0149] Example 4

[0150] The method for determining the hydration performance index of silicate cement described in this invention was used to calculate and analyze the hydration heat release rate of cement. The calculation method is roughly the same as that in Example 1, and the calculation parameters introduced are shown in Table 1.

[0151] The specific characteristics of the materials and the experimental environment are as follows: the mineral components of the silicate cement are: tricalcium silicate 74.15%, tricalcium aluminate 6.18%, tetracalcium aluminoferrite 8.1%, dicalcium silicate 5.79%, and gypsum 4.03%; the water-cement ratio is 0.4; and the specific surface area of ​​the silicate cement is 1000 m². 2 / kg; ambient temperature is 20℃;

[0152] The relationship between the theoretically determined and experimentally measured results of the heat release rate of silicate cement hydration paste calculated using the method described in this embodiment and the hydration time is shown in the figure. Figure 7 The results show that the analytical method described in this invention has high accuracy in determining the heat release rate of the entire hydration process of silicate cement.

[0153] Example 5

[0154] The method for determining the hydration performance index of silicate cement described in this invention was used to calculate and analyze the hydration heat release rate of cement. The calculation method is roughly the same as that in Example 1, and the calculation parameters introduced are shown in Table 1.

[0155] The specific characteristics of the materials and the experimental environment are as follows: the mineral components of the silicate cement are: tricalcium silicate 68.2%, tricalcium aluminate 5.1%, tetracalcium aluminoferrite 11.4%, dicalcium silicate 7.1%, and gypsum 3.1%; the water-cement ratio is 0.5; and the specific surface area of ​​the silicate cement is 1000 m². 2 / kg; ambient temperature is 20℃;

[0156] The relationship between the theoretically determined and experimentally measured results of the heat release rate of silicate cement hydration paste calculated using the method described in this embodiment and the hydration time is shown in the figure. Figure 8 The results show that the analytical method described in this invention has high accuracy in determining the heat release rate of the entire hydration process of silicate cement.

[0157] Example 6

[0158] The method for determining the hydration performance index of silicate cement described in this invention was used to calculate and analyze the hydration heat release rate of cement. The calculation method is roughly the same as that in Example 1, and the calculation parameters introduced are shown in Table 1.

[0159] The specific characteristics of the materials and the experimental environment are as follows: the mineral components of the silicate cement are: tricalcium silicate 57.7%, tricalcium aluminate 10.4%, tetracalcium aluminoferrite 1.9%, dicalcium silicate 19.7%, and gypsum 3.8%; the water-cement ratio is 0.5; and the specific surface area of ​​the silicate cement is 1000 m². 2 / kg; ambient temperature is 23℃;

[0160] The relationship between the theoretically determined and experimentally measured results of the heat release rate of silicate cement hydration paste calculated using the method described in this embodiment and the hydration time is shown in the figure. Figure 9 The results show that the analytical method described in this invention has high accuracy in determining the heat release rate of the entire hydration process of silicate cement.

[0161] Table 1. Calculation parameters referenced in the methods described in Examples 1–6.

[0162]

[0163]

[0164] Although the present invention has been described herein with reference to illustrative embodiments, the above embodiments are merely preferred embodiments of the present invention, and the implementation of the present invention is not limited to the above embodiments. It should be understood that those skilled in the art can devise many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. A method for determining the hydration performance indicators of silicate cement, characterized in that... The steps include the following: 1) Based on the different dissolution characteristics of each mineral component in silicate cement and the different deposition characteristics of each hydration product, and based on the saturation state of ion concentration in the hydration slurry, establish mathematical relationships between the dissolution of each mineral phase, deposition of hydration products, ion adsorption rate and ion concentration. 2) Based on the mathematical relationships between the rates and ion concentrations established above, and combined with the diffusion coefficients of each ion in the hydration slurry, establish chemical field control equations reflecting the coupling effects of mineral phase dissolution, product deposition, ion diffusion, and ion adsorption reactions during the hydration process, as well as electric potential and temperature field control equations; and solve the three sets of control equations by combining the corresponding boundary and initial conditions, outputting the results of the changes in ion concentration, electric potential, and temperature over time and their spatial distribution throughout the entire hydration process. 3) Based on the above output results of ion concentration, potential and temperature changes over time, calculate the dissolution rate of each mineral phase and the deposition rate of hydration products, and establish (a) the heat release rate of surface water wetting adsorption and initial hydration of mineral phases respectively. Calculation formula, (b) the exothermic rate of the chemical reaction between the silicon and aluminum phases and water. The calculation formula, by superimposing the heat release rates of the two processes, establishes the heat of hydration for the entire hydration process of silicate cement. Calculation formula , ;in and These represent the heat release rates of the silicon phase and the aluminum phase, respectively. In step 1), the method for establishing the mathematical relationship between the dissolution reaction rate of each mineral phase, the deposition reaction rate of hydration products, the ion adsorption rate and the ion concentration in the entire hydration process is based on the driving and controlling effect of the saturation state of each ion concentration on the dissolution, product deposition, ion diffusion and ion adsorption reaction rates of each mineral phase. The formulas for calculating the dissolution rate of tricalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, dicalcium silicate and gypsum mineral phases, the deposition rate of hydration products of hydrated calcium silicate, calcium hydroxide, ettringite and monosulfide hydrated calcium sulfoaluminate, and the adsorption rate of calcium ion, aluminate ion and sulfate ion hydration reaction ions are established respectively. In step 2), the methods for coupling the mineral phase dissolution reaction, product deposition reaction, ion diffusion reaction, and ion adsorption reaction in the hydration process within the same chemical field governing equation include: Based on the established formulas for calculating the mineral phase dissolution rate, product deposition rate, and ion adsorption rate, the formulas for calculating the release of Ca during the mineral phase dissolution process are established respectively. 2+ H3SiO4 - Al(OH)4 - OH - SO4 2- The rate formulas for the ion diffusion process, the rate formulas for the consumption of each ion during product deposition, and the rate formulas for the consumption of each ion during ion adsorption are established. Simultaneously, based on the driving effects of ion concentration gradient, ion potential gradient, and chemical activity gradient on the ion diffusion process, diffusion equations for each ion during the hydration process are established. The rate formulas for the release of ions during mineral phase dissolution, the consumption of ions during product deposition, and the consumption of ions during ion adsorption are substituted into the ion diffusion equations and coupled to the same governing equation, as shown in equations 35-37 below. (35) (36) (37)； In the formula, , , , , These represent the diffusion flux, diffusion coefficient, ion valence, concentration, and ion activity coefficient for different types of ions, respectively. This indicates the first [issue] caused by the dissolution of silicate cement. k The rate of formation of seed ions; Indicates the first The adsorption rate of the seed ions; , , , , They represent the first Stoichiometric coefficients of seed ions in the Ca2SO4·H2O dissolution reaction and the deposition reaction of CSH, CH, AFt, and AFm; , , , , They represent the dissolution rate of Ca2SO4·H2O and the deposition rates of CSH, CH, AFt, and AFm, respectively. Represents the Hamiltonian operator; It is Faraday's constant. It is the ideal gas constant. It is the temperature of the hydrated slurry; Represents electric potential; , , , They represent the first Stoichiometric coefficients of seed ions in the dissolution reactions of C3S, C3A, C4AF, and C2S; , , , The dissolution reaction rates of C3S, C3A, C4AF, and C2S are represented respectively. In step 2), the method for constructing the electric potential field includes: Based on the electric potential field formed by the non-uniform distribution of electrically dissimilar ions in the hydration slurry and its driving effect on the ion diffusion process, the electric field control equation for the hydration process was established using the Poisson equation, as shown below: (38) In the formula, , , and These are, respectively, Faraday constant, ion valence, dielectric constant of water, and vacuum dielectric constant; Represents electric potential; In step 2), the method for constructing the temperature field includes: Based on the heat conduction process of the slurry, the heat conduction control equations for the temperature field are established, as shown in equations 39-43: (39) (40) (41) (42) (43) In the formula, , , These represent the densities of the slurry, water, and cement, respectively. , , These represent the specific heat capacities of the slurry, water, and cement, respectively. , , , , , , , These represent the thermal conductivity of the slurry, the heat released by the complete hydration of C3A per unit volume, the surface ion adsorption rate constant, the water-cement ratio, the gypsum content, the heat released by the complete hydration of C3A per unit mass, the specific surface area of ​​the particles, and the surface area of ​​cement particles in the hydrated slurry per unit volume, respectively. Indicates hydration time. This indicates the temperature of the slurry.

2. The method for determining the hydration performance index of silicate cement according to claim 1, characterized in that: The formulas for calculating the dissolution rate of tricalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, dicalcium silicate, and gypsum mineral phases; the formulas for calculating the deposition rate of hydration products of hydrated calcium silicate, calcium hydroxide, ettringite, and monosulfide-type hydrated calcium sulfoaluminate; and the formulas for calculating the adsorption rate of calcium ions, aluminate ions, and sulfate ions in the hydration reaction are shown in Equation 10-31 below: (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) In the formula, the subscript Indicates the type of ion, namely Ca 2+ H3SiO4 - Al(OH)4 - OH - SO4 2- ; , These represent the concentration and activity coefficient of different types of ions, respectively. , , , , They represent the dissolution rate of Ca2SO4·H2O and the deposition rates of CSH, CH, AFt, and AFm, respectively. , , , The dissolution reaction rates of C3S, C3A, C4AF, and C2S are represented respectively. , , , , These represent the contents of C3S, C3A, C4AF, C2S, and Ca2SO4·H2O in cement, respectively. , , , , , , , , denoted as the reaction rate constants for the dissolution of C3S, C3A, C4AF, C2S, and Ca2SO4·H2O, and the deposition of CSH, CH, AFt, and AFm, respectively. , , , , , , , , , respectively, represent the reaction equilibrium constants for the dissolution of C3S, C3A, C4AF, C2S, and Ca2SO4·H2O, and the deposition of CSH, CH, AFt, and AFm; , , Representing Ca 2+ Al(OH)4 - SO4 2- The adsorption rate constant; , These represent the surface areas of cement particles and gypsum particles per unit volume of slurry, respectively; w / c represents the water-cement ratio.

3. The method for determining the hydration performance index of silicate cement according to claim 2, characterized in that: In step 2), the boundary conditions are applied as follows: The slurry comes into contact with the indoor air environment at its edge, and its temperature at that boundary is room temperature; therefore, the temperature field is... r The boundary condition at =λ is a Dirichlet boundary condition, as shown below: (44) In the formula, Indicates room temperature. r Let λ be the spatial location variable within the slurry domain, and λ be the radius of the slurry domain. The center of the slurry is the center of symmetry, and the partial derivative of the temperature field at this boundary is zero; therefore, the temperature field at... r The boundary conditions at =0 are Neumann boundary conditions, as shown below: (45) The ion concentration at the particle surface is saturated, and the surface is considered as the zero potential point; therefore, the chemical field and the electric potential field are... r The boundary condition at =0 is a Dirichlet boundary condition, as shown below: , , , , , (46) In the formula, , , , Representing Ca 2+ H3SiO4 - Al(OH)4 - OH - The saturation concentration of ions; The right boundary of the ion diffusion domain is the surface of the gypsum particles, where the partial derivatives of the chemical and electric potential fields are zero; therefore, the chemical and electric potential fields are... ξ = L The boundary conditions at point are Neumann boundary conditions, as shown in the following equation; where ξ For spatial position variables in the ion diffusion domain, L It is the length of the ion diffusion domain; , , , , , (47) In the formula, , Representing Ca 2+ SO4 2- The saturation concentration of ions, ξ is the spatial position variable in the ion diffusion domain.

4. The method for determining the hydration performance index of silicate cement according to claim 3, characterized in that: In step 2), the initial conditions are as follows: , , (48)。 5. The method for determining the hydration performance index of silicate cement according to any one of claims 1 to 4, characterized in that: To simplify calculations, the governing equations for the temperature, chemical, and electric potential fields are treated dimensionlessly, and dimensionless parameters are set as follows: (49) In the formula, , , , , These represent dimensionless position coordinates, time coordinates, temperature, electric potential, and ion concentration, respectively. , , , , These represent characteristic length, characteristic time, characteristic temperature, characteristic potential, and characteristic ion concentration, respectively.

6. The method for determining the hydration performance index of silicate cement according to claim 5, characterized in that: In step 3), the method for constructing the formula for calculating the hydration heat release rate of silicate cement includes the following: ① Based on the reasons for heat generation during cement hydration, heat sources are divided into two categories, as detailed below: Analyzing the various reactions and effects occurring during the hydration process, the essential reasons for heat release can be summarized as follows: (a) heat generated by surface water wetting and adsorption, and the initial hydration of the mineral phase. (b) The heat generated by the chemical reaction of the silicon and aluminum phases with water. Both types of heat release involve the entire process of hydration, including the pre-induction phase, induction phase, acceleration phase, deceleration phase, and stabilization phase. ② Establish calculation formulas for the exothermic rates of surface moisture wetting and adsorption, initial hydration of mineral phases, and chemical reactions of silicon and aluminum phases with water, respectively. Superimpose the exothermic rates of the two processes to establish a method for determining the heat of hydration of silicate cement throughout the entire hydration process. The specific process is as follows: (a) Based on the heat release characteristics of surface moisture wetting and adsorption and initial hydration of mineral phases, a formula for calculating the heat release rate is established as follows: (50) (b) Based on the exothermic reasons of the chemical reactions of silicon and aluminum phases with water, the dissolution rates of C3S and C2S are integrated over the space and time of the slurry to obtain the total amount of C3S and C2S consumed. This is then multiplied by the total heat released per mole of C3S consumed to obtain the exothermic heat of the silicon phase reaction. Simultaneously, the deposition reaction rates of AFt and AFm are integrated over the space and time of the slurry to obtain the total amount of AFt and AFm generated. This is then multiplied by the heat release per mole of AFt and AFm generated to obtain the heat release of the aluminum phase reaction. The two are summed to establish the calculation formula for the exothermic heat of hydration of silicon and aluminum phases, as shown in Equations 52-59: (52) (53) (54) (55) (56) (57) (58) (59) In the formula, , , , , , , respectively, represent the convective heat transfer coefficient of the slurry, the specific heat capacity of the silicon phase, the specific heat capacity of C3A, the total heat of the C3S hydration reaction, the total heat of the C2S hydration reaction, and the activation energy of the C2S hydration reaction; , , , These represent the total heat release per unit mole of C3A hydration reaction to generate AFt, the total heat release per unit mole of C3A hydration reaction to generate AFm, the molar ratio of C3A hydration reaction to generate AFt, and the molar ratio of C3A hydration reaction to generate AFm, respectively. The heat generated by (a) surface water wetting and adsorption, and initial hydration of mineral phases (b) Thermal release from the chemical reaction of silicon and aluminum phases with water By combining these two methods, a method for determining the hydration heat release rate throughout the entire hydration process of silicate cement is established, as shown below: (60)。 7. An analytical apparatus employing the method for determining the hydration performance index of silicate cement as described in any one of claims 1 to 6, characterized in that: It includes an input module, a calculation module, and an output module; Input module: Used to input the initial condition parameters of the silicate cement hydration process, including the C3S content, C3A content, C4AF content, C2S content, Ca2SO4·H2O content, water-cement ratio, specific surface area, and curing temperature in the cement; Calculation module: Based on the initial and boundary condition parameters, using the chemical field governing equations of the cement hydration process, calculates Ca. 2+ H3SiO4 - Al(OH)4 - OH - SO4 2- The changes in ion concentration, C3S content, dissolution rates of C3A, C4AF, C2S, and Ca2SO4·H2O, and deposition rates of CSH, CH, AFt, and AFm over time were studied. Based on these reaction rates, the heat release of the initial dissolution, silicon phase, and aluminum phase hydration reactions was calculated separately. The two were then superimposed to obtain the heat release rate of the entire silicate cement hydration process. Output module: Used to output the calculated heat of hydration as a function of time.

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