Method and system for evaluating damage degree of fly ash / silica fume modified magnesium phosphate cement after high temperature

Abstract

The invention discloses a method and a system for evaluating the damage degree of fly ash / silica fume modified magnesium phosphate cement after high temperature, and relates to the technical field of detection and evaluation application of fly ash / silica fume modified magnesium phosphate cement after high temperature. Comprising the following steps: processing compressive strength and pore structure data of a fly ash / silica fume modified magnesium phosphate cement sample subjected to different temperature actions to obtain a degradation rate and a degradation coefficient of the sample subjected to different temperature actions so as to determine a sample safety threshold; compressive strength and pore structure data are processed to determine related factors highly related to compressive strength and damage weights occupied by the related factors, when a to-be-detected sample is evaluated, damage degree evaluation coefficients are generated in combination with data deviation of the related factors and the damage weights, and then damage degree grading is carried out. The effect of qualitatively and quantitatively evaluating the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be detected is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of detection and evaluation application of fly ash / silica fume modified magnesium phosphate cement after high temperature, and in particular to a method and system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature. Background Art

[0002] Magnesium phosphate cement, also known as a chemically bonded ceramic, is a novel inorganic cementitious material composed of magnesium oxide, phosphate, and water in a specific ratio. Due to its advantages such as good environmental adaptability, excellent volume stability, and excellent bonding with old concrete, it is primarily used in fields such as rapid repair of concrete structures, biomedicine, and the solidification of heavy metals and radioactive waste. Fly ash and silica fume are two common industrial wastes. When added to magnesium phosphate cement, they can reduce hydration heat, increase compressive strength, and optimize pore structure. In recent years, with the application of magnesium phosphate cement as a refractory material and steel fireproof coating in high-temperature environments, the high-temperature resistance of magnesium phosphate cement has attracted the attention of many practitioners. Existing research has mostly focused on the performance and deterioration mechanisms of magnesium phosphate cement after high temperatures, but few methods have been mentioned to assess the degree of damage to fly ash / silica fume-modified magnesium phosphate cement after high temperatures.

[0003] Therefore, how to provide a method and system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature to improve the safety and reliability of fly ash / silica fume modified magnesium phosphate cement in high temperature environments and promptly discover problems and defects of fly ash / silica fume modified magnesium phosphate cement in high temperature environments is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a method and system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, which can achieve the effect of qualitatively and quantitatively evaluating the degree of damage of the fly ash / silica fume modified magnesium phosphate cement to be tested.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature treatment comprises the following steps: S1. preparing a certain number of fly ash / silica fume modified magnesium phosphate cement samples, curing them, and calcining them at different temperatures to obtain calcined fly ash / silica fume modified magnesium phosphate cement samples; S2. Analyze fly ash / silica fume modified magnesium phosphate cement samples after calcination at different temperature intervals. Based on the pore size, the pores are divided into gel pores, fine capillary pores, medium capillary pores, large capillary pores, and macropores. The action temperature is divided into multiple temperature intervals. The compressive strength, total porosity, and pore size ratio of each type of pore are obtained for at least two fly ash / silica fume modified magnesium phosphate cement samples at the corresponding temperature in each temperature interval. The pore size ratio of each type of pore is multiplied by the total porosity to generate gel pore porosity, small capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, and macropore porosity to obtain sample data. S3. Construct a compressive strength prediction function including undetermined coefficients, and obtain the correction coefficient and degradation rate that vary with the action temperature as the undetermined coefficients based on the sample data; S4. Determine the correlation coefficient between the compressive strength of the fly ash / silica fume modified magnesium phosphate cement sample and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio, and large pore size ratio based on the sample data, and determine the relevant factors that are strongly correlated with the compressive strength based on the magnitude of the correlation coefficient; S5. Filtering data corresponding to relevant factors from the sample data, and establishing a relevant factor prediction function based on a cubic spline interpolation function technique; S6. Obtain data on the total porosity and pore size ratio of each type of porosity of the same fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, thereby generating the porosity of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, and based on the porosity, generate the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures; S7. Determine the temperature range and degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample according to its operating temperature, calculate the ratio between the degradation coefficient and the degradation rate, divide the above ratio into temperature ranges corresponding to the relevant temperatures, and determine the maximum value of the ratio of the degradation coefficient to the degradation rate in the temperature range as the safety threshold; S8. Obtain the total porosity, pore size ratio of each type of pore, and operating temperature of the fly ash / silica fume modified magnesium phosphate cement to be evaluated, obtain the porosity, degradation coefficient, and degradation rate of each type of pore, calculate the ratio of the degradation coefficient to the degradation rate, and compare it with the safety threshold; S9. When the ratio is not greater than the safety threshold, the degree of damage of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after high temperature is deemed normal. Otherwise, the damage degree coefficient used to measure the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples are combined with the correlation coefficients corresponding to the relevant factors and the differences in relevant factors between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples are calculated, and the damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined based on the size of the damage degree assessment coefficient.

[0006] Optionally, S3 includes: establishing a prediction function for the compressive strength of fly ash / silica fume modified magnesium phosphate cement samples after high temperature treatment, the corresponding expression being: , in, T represents the temperature number, and T =0℃、105℃、200℃、400℃、……、 t ℃, t Indicates the operating temperature, It means that fly ash / silica fume modified magnesium phosphate cement is T The compressive strength after action, T The compressive strength after action, T 1 T 2 …、 T i 、…、 T n are all specific temperatures within the temperature range. i represents different temperature ranges, and i =1, 2, 3, ..., n , n is the total number of temperature intervals set in the test, and n ≤ T , …、 …、 and …、 …、 are all undetermined coefficients, and …、 …、 are the correction constants corresponding to different temperature ranges, …、 、 …、 are the degradation rates corresponding to different temperature ranges, and the compressive strength and corresponding action temperature collected from each fly ash / silica fume modified magnesium phosphate cement sample are substituted into the compressive strength prediction function to form the undetermined coefficient …、 …、 and …、 、 …、 The multivariate linear equations are ensured to have a larger number of equations than the number of coefficients to be determined, and then the coefficients to be determined are solved based on the least squares method. …、 …、 and …、 、 …、 The solution is obtained and the unknown coefficients are inferred, thereby establishing a prediction function for the compressive strength of fly ash / silica fume modified magnesium phosphate cement.

[0007] Optionally, S4 includes: calculating, based on a Pearson correlation calculation formula, a correlation coefficient between the compressive strength of the fly ash / silica fume modified magnesium phosphate cement and the gel pore size ratio, the small capillary pore size ratio, the medium capillary pore size ratio, the large capillary pore size ratio, and the large pore size ratio; A correlation threshold is preset. When the correlation coefficient between compressive strength and gel pore diameter ratio is greater than the correlation threshold, the gel pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and small capillary pore diameter ratio is greater than the correlation threshold, the small capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and medium capillary pore diameter ratio is greater than the correlation threshold, the medium capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and large capillary pore diameter ratio is greater than the correlation threshold, the large capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and large pore diameter ratio is greater than the correlation threshold, the large pore diameter ratio is determined as a related factor strongly correlated with the compressive strength.

[0008] Optionally, the relationship between compressive strength and gel pore size ratio is expressed as: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T Compressive strength after action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average compressive strength after the action, x is the number of the different fly ash / silica fume modified magnesium phosphate cement samples, and x =1, 2, 3..., X , X is the total number of fly ash / silica fume modified magnesium phosphate cement samples, and ; For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of gel pore size after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of the gel pores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of gel pore size; The expression of compressive strength and small pore size ratio is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of small capillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperatureT The average pore size ratio of fine capillaries after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of fine capillary pores; The expression of compressive strength and mesopore diameter ratio is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of mesocapillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of mesocapillaries after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of mesopores; The expression of compressive strength and the ratio of large pore diameter is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of large capillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of large capillary pores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of large capillary pores; The expression of compressive strength and macropore diameter ratio is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of macropore diameter after the effect; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of macropores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of macropore size.

[0009] Optionally, the expression of the degradation coefficient in S5 is: in, KX z ( T) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Total porosity after ℃ action; KX Gel ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T The porosity of the gel after ℃ action; KX Fin,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T The porosity of small capillary pores after the action of ℃; KX Med,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Mesocapillary porosity after ℃ action; KX Lar,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Macrocapillary porosity after ℃ action; KX Lar ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Macroporosity after ℃ action; Z z ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the total porosity increases compared with the previous temperature range; Z Gel ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the porosity of the gel pores increases compared with the previous temperature range; Z Fin,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the capillary porosity increases compared with the previous temperature range; Z Med,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the mesocapillary porosity increases compared with the previous temperature range; Z Lar,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the macrocapillary porosity increases compared with the previous temperature range;Z Lar ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the macropore porosity increases compared with the previous temperature range. Ygp ( T ) Fly ash / silica fume modified magnesium phosphate cement samples at ambient temperature T Deterioration coefficient after the action of ℃.

[0010] Optionally, determining the level of damage includes the following steps: The operating temperature at which the degradation coefficient and degradation rate ratio of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is greater than the safety threshold is determined as the abnormal temperature, and the number of related factors is determined; When the number of relevant factors is 1, calculate the relative error of the relevant factor data in the fly ash / silica fume modified magnesium phosphate cement and fly ash / silica fume modified magnesium phosphate cement samples to be evaluated after the abnormal temperature, and multiply the relative error by the correlation coefficient corresponding to the relevant factor to obtain the damage degree assessment coefficient; When the number of relevant factors is greater than 1, the correlation coefficients corresponding to each relevant factor are scaled proportionally, with the cumulative value equal to 1 as the constraint, to generate damage weights corresponding to each relevant factor. The relative errors of the relevant factors in the fly ash / silica fume modified magnesium phosphate cement and fly ash / silica fume modified magnesium phosphate cement samples to be evaluated after abnormal temperature are calculated, and the relative errors of each relevant factor are multiplied by the corresponding damage weight and accumulated to obtain the damage degree assessment coefficient. The damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined according to the damage degree assessment coefficient.

[0011] A system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, for executing any of the above-mentioned methods for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, comprising a sample acquisition module, a data acquisition module, a degradation rate calculation module, a related factor determination module, a related factor prediction module, a degradation coefficient calculation module, a safety threshold calculation module, a damage degree preliminary judgment module, and a damage degree assessment module connected in sequence; Sample acquisition module: prepare a certain number of fly ash / silica fume modified magnesium phosphate cement samples, and calcine them at different temperatures after curing to obtain calcined fly ash / silica fume modified magnesium phosphate cement samples; Data acquisition module: Analyze fly ash / silica fume modified magnesium phosphate cement samples calcined at different temperature ranges, and divide the pores into gel pores, fine capillary pores, medium capillary pores, large capillary pores, and macropores based on pore size. The operating temperature is divided into multiple temperature ranges, and the compressive strength, total porosity, and pore size ratio data of at least two fly ash / silica fume modified magnesium phosphate cement samples are obtained at the corresponding temperature in each temperature range. The pore size ratio of each pore is multiplied by the total porosity to generate gel pore porosity, small capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, and macropore porosity to obtain sample data; Deterioration rate calculation module: Construct a compressive strength prediction function including undetermined coefficients, and combine sample data to obtain the correction coefficient and degradation rate that vary with the action temperature as the undetermined coefficients; Correlation factor determination module: Determine the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement samples and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio and large pore size ratio data based on the sample data, and determine the correlation factor that is strongly correlated with the compressive strength based on the size of the correlation coefficient; Related factor prediction module: Filters data corresponding to related factors from sample data and establishes related factor prediction function based on cubic spline interpolation function technology; Deterioration coefficient calculation module: Obtain the total porosity and pore size ratio data of the same fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, thereby generating the porosity of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures. Based on the porosity, the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures is generated; Safety threshold calculation module: Determine the temperature range and degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample based on its working temperature, calculate the ratio between the degradation coefficient and the degradation rate, divide the above ratio into the temperature range corresponding to the relevant temperature, and determine the maximum value of the ratio of the degradation coefficient to the degradation rate in the temperature range as the safety threshold; Preliminary damage assessment module: This module obtains the total porosity, pore size ratio of each type of pore, and the operating temperature of the fly ash / silica fume modified magnesium phosphate cement to be evaluated. It then obtains the porosity, degradation coefficient, and degradation rate of each type of pore. It then calculates the ratio of the degradation coefficient to the degradation rate and compares it with the safety threshold. Damage degree assessment module: When the ratio is not greater than the safety threshold, the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after high temperature is considered normal. Otherwise, the damage degree coefficient used to measure the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples is calculated based on the correlation coefficient corresponding to the relevant factors and the difference in relevant factors between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples. The damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined based on the size of the damage degree assessment coefficient.

[0012] It can be seen from the above technical solution that compared with the prior art, the present invention provides a method and system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, which has the following beneficial effects: the present invention processes the compressive strength data of fly ash / silica fume modified magnesium phosphate cement samples cured indoors after high temperature to obtain the degradation rate of fly ash / silica fume modified magnesium phosphate cement after different temperatures, and processes the pore structure data of fly ash / silica fume modified magnesium phosphate cement samples after different temperatures to obtain the degradation coefficient of fly ash / silica fume modified magnesium phosphate cement after different temperatures, and then combines the degradation rate and degradation coefficient to determine the safety threshold of fly ash / silica fume modified magnesium phosphate cement after high temperature, so as to achieve the purpose of measuring the high damage of fly ash / silica fume modified magnesium phosphate cement through the pore structure at the micro level. The purpose of this paper is to determine the degree of damage after high temperature, and to determine the relevant factors that are strongly correlated with the compressive strength by processing the compressive strength and pore structure data, and to determine the damage weight according to the correlation coefficient corresponding to the relevant factors. When evaluating the damage of the fly ash / silica fume modified magnesium phosphate cement to be evaluated, the data deviation of the relevant factors and their corresponding damage weights are combined to generate a damage degree assessment coefficient for measuring the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated, and the damage degree is graded according to the damage degree assessment coefficient, so as to achieve the effect of qualitative and quantitative evaluation of the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after high temperature, and to provide important guarantee for timely discovery of problems and defects in the application of fly ash / silica fume modified magnesium phosphate cement in high temperature environment, and to ensure that the quality of fly ash / silica fume modified magnesium phosphate cement after high temperature can still meet the relevant application specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0014] Figure 1This is a flow chart of a method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, disclosed in the present invention; Figure 2 The present invention discloses a block diagram of a system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature. DETAILED DESCRIPTION

[0015] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0016] Reference Figure 1 As shown, the present invention discloses a method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, comprising the following steps: S1. preparing a certain number of fly ash / silica fume modified magnesium phosphate cement samples, curing them, and calcining them at different temperatures to obtain calcined fly ash / silica fume modified magnesium phosphate cement samples; S2. Analyze fly ash / silica fume modified magnesium phosphate cement samples after calcination at different temperature intervals. Based on the pore size, the pores are divided into gel pores, fine capillary pores, medium capillary pores, large capillary pores, and macropores. The action temperature is divided into multiple temperature intervals. The compressive strength, total porosity, and pore size ratio of each type of pore are obtained for at least two fly ash / silica fume modified magnesium phosphate cement samples at the corresponding temperature in each temperature interval. The pore size ratio of each type of pore is multiplied by the total porosity to generate gel pore porosity, small capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, and macropore porosity to obtain sample data. S3. Construct a compressive strength prediction function including undetermined coefficients, and obtain the correction coefficient and degradation rate that vary with the action temperature as the undetermined coefficients based on the sample data; S4. Determine the correlation coefficient between the compressive strength of the fly ash / silica fume modified magnesium phosphate cement sample and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio, and large pore size ratio based on the sample data, and determine the relevant factors that are strongly correlated with the compressive strength based on the magnitude of the correlation coefficient; S5. Filtering data corresponding to relevant factors from the sample data, and establishing a relevant factor prediction function based on a cubic spline interpolation function technique; S6. Obtain data on the total porosity and pore size ratio of each type of porosity of the same fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, thereby generating the porosity of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, and based on the porosity, generate the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures; S7. Determine the temperature range and degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample according to its operating temperature, calculate the ratio between the degradation coefficient and the degradation rate, divide the above ratio into temperature ranges corresponding to the relevant temperatures, and determine the maximum value of the ratio of the degradation coefficient to the degradation rate in the temperature range as the safety threshold; S8. Obtain the total porosity, pore size ratio of each type of pore, and operating temperature of the fly ash / silica fume modified magnesium phosphate cement to be evaluated, obtain the porosity, degradation coefficient, and degradation rate of each type of pore, calculate the ratio of the degradation coefficient to the degradation rate, and compare it with the safety threshold; S9. When the ratio is not greater than the safety threshold, the degree of damage of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after high temperature is deemed normal. Otherwise, the damage degree coefficient used to measure the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples are combined with the correlation coefficients corresponding to the relevant factors and the differences in relevant factors between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples are calculated, and the damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined based on the size of the damage degree assessment coefficient.

[0017] Furthermore, the curing and calcining in S1 includes curing in a room environment at a temperature of 20±5°C and a humidity of 50±5°C for 28 days and then moving the material into a muffle furnace for calcination.

[0018] Furthermore, the pore classification criteria in S2 include: Pores with a pore size of 0-10 nm are classified as gel pores (excluding 10 nm); Pores with a pore size of 10-50 nm are classified as fine capillary pores (excluding 50 nm); Pores with a pore size of 50-100 nm are classified as mesocapillary pores (excluding 100 nm); Pores with a pore size of 100 nm-10 μm are classified as large capillary pores (excluding 10 μm); Pores with a diameter greater than 10 μm are classified as macropores.

[0019] Furthermore, obtaining the pore ratio in S2 includes: using NMR technology to determine the specific pore size of each pore in the fly ash / silica fume modified magnesium phosphate cement sample, and further processing the pore size distribution of each type of pore inside the magnesium phosphate cement sample, so as to obtain the specific ratio of each type of pore in the total porosity.

[0020] Furthermore, S3 includes: establishing a prediction function for the compressive strength of fly ash / silica fume modified magnesium phosphate cement samples after high temperature, and the corresponding expression is: , in, T represents the temperature number, and T =0℃、105℃、200℃、400℃、……、 t ℃, t Indicates the operating temperature, It means that fly ash / silica fume modified magnesium phosphate cement is T The compressive strength after action, T 1 T 2 …、 T i 、…、 T n are all specific temperatures within the temperature range. i represents different temperature ranges, and i =1, 2, 3, ..., n , n is the total number of temperature intervals set in the test, and n ≤ T , …、 …、 and …、 …、 are all undetermined coefficients, and …、 …、 are the correction constants corresponding to different temperature ranges, …、 、 …、 are the degradation rates corresponding to different temperature ranges, and the compressive strength and corresponding action temperature collected from each fly ash / silica fume modified magnesium phosphate cement sample are substituted into the compressive strength prediction function to form the undetermined coefficient …、 …、 and …、 、 …、 The multivariate linear equations are ensured to have a larger number of equations than the number of coefficients to be determined, and then the coefficients to be determined are solved based on the least squares method. …、 …、 and …、 、 …、 The solution is obtained and the unknown coefficients are inferred, thereby establishing a prediction function for the compressive strength of fly ash / silica fume modified magnesium phosphate cement.

[0021] Furthermore, S4 includes: calculating the correlation coefficient between the compressive strength of the fly ash / silica fume modified magnesium phosphate cement and the gel pore size ratio, the small capillary pore size ratio, the medium capillary pore size ratio, the large capillary pore size ratio and the large pore size ratio based on the Pearson correlation calculation formula; A correlation threshold is preset. When the correlation coefficient between compressive strength and gel pore diameter ratio is greater than the correlation threshold, the gel pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and small capillary pore diameter ratio is greater than the correlation threshold, the small capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and medium capillary pore diameter ratio is greater than the correlation threshold, the medium capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and large capillary pore diameter ratio is greater than the correlation threshold, the large capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and large pore diameter ratio is greater than the correlation threshold, the large pore diameter ratio is determined as a related factor strongly correlated with the compressive strength.

[0022] Furthermore, the relationship between compressive strength and gel pore size ratio is expressed as: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T Compressive strength after action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average compressive strength after the action, x is the number of the different fly ash / silica fume modified magnesium phosphate cement samples, and x =1, 2, 3..., X , X is the total number of fly ash / silica fume modified magnesium phosphate cement samples, and ; The xth fly ash / silica fume modified magnesium phosphate cement at temperature T The proportion of gel pore size after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of the gel pores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of gel pore size; The expression of compressive strength and small pore size ratio is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of small capillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of fine capillaries after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of fine capillary pores; The expression of compressive strength and mesopore diameter ratio is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of mesocapillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of mesocapillaries after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of mesopores; The expression of compressive strength and the ratio of large pore diameter is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of large capillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of large capillary pores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of large capillary pores; The expression of compressive strength and macropore diameter ratio is: , in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of macropore diameter after the effect; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of macropores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of macropore size.

[0023] Furthermore, the expression of the degradation coefficient in S5 is: in, KX z ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Total porosity after ℃ action; KX Gel ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T The porosity of the gel after ℃ action; KX Fin,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T The porosity of small capillary pores after the action of ℃; KX Med,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Mesocapillary porosity after ℃ action; KX Lar,cap (T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Macrocapillary porosity after ℃ action; KX Lar ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Macroporosity after ℃ action; Z z ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the total porosity increases compared with the previous temperature range; Z Gel ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the porosity of the gel pores increases compared with the previous temperature range; Z Fin,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the capillary porosity increases compared with the previous temperature range; Z Med,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the mesocapillary porosity increases compared with the previous temperature range; Z Lar,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the macrocapillary porosity increases compared with the previous temperature range; Z Lar ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the macropore porosity increases compared with the previous temperature range. Ygp ( T ) Fly ash / silica fume modified magnesium phosphate cement samples at ambient temperature T Deterioration coefficient after the action of ℃.

[0024] Specifically, Ygp ( T) represents the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to an ambient temperature of T℃, which is composed of the growth of gel pore porosity, fine capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, macropore porosity and total porosity. The larger the degradation coefficient, the more serious the high-temperature damage of the fly ash / silica fume modified magnesium phosphate cement sample, that is, the more serious the degradation of the hydration product of the fly ash / silica fume modified magnesium phosphate cement sample, the greater the porosity increase caused by the evaporation of free water and bound water under high temperature environment, the faster the degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample, and the more likely it is that the compressive strength does not meet the standard, indicating that the fly ash / silica fume modified magnesium phosphate cement is seriously damaged by high temperature.

[0025] Furthermore, the degradation rate in S7 uses the degradation rate obtained in S3. For different temperature ranges, the degradation rate of the fly ash / silica fume modified magnesium phosphate cement samples is different, and the degradation rate of the fly ash / silica fume modified magnesium phosphate cement is positively correlated with the damage rate. Therefore, the method of step S7 is used to obtain the safety threshold of each temperature range. When the fly ash / silica fume modified magnesium phosphate cement sample to be evaluated is subsequently evaluated, if the ratio of the degradation coefficient and the degradation rate of the sample to be evaluated is greater than the safety threshold, it means that the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is too large, that is, the fly ash / silica fume modified magnesium phosphate cement to be evaluated is seriously deteriorated and is prone to compressive strength failure, indicating that the fly ash / silica fume modified magnesium phosphate cement to be evaluated is more seriously damaged by temperature.

[0026] Furthermore, determining the damage level includes the following steps: The operating temperature at which the degradation coefficient and degradation rate ratio of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is greater than the safety threshold is determined as the abnormal temperature, and the number of related factors is determined; When the number of relevant factors is 1, calculate the relative error of the relevant factor data in the fly ash / silica fume modified magnesium phosphate cement and fly ash / silica fume modified magnesium phosphate cement samples to be evaluated after the abnormal temperature, and multiply the relative error by the correlation coefficient corresponding to the relevant factor to obtain the damage degree assessment coefficient; When the number of relevant factors is greater than 1, the correlation coefficients corresponding to each relevant factor are scaled proportionally, with the cumulative value equal to 1 as the constraint, to generate damage weights corresponding to each relevant factor. The relative errors of the relevant factors in the fly ash / silica fume modified magnesium phosphate cement and fly ash / silica fume modified magnesium phosphate cement samples to be evaluated after abnormal temperature are calculated, and the relative errors of each relevant factor are multiplied by the corresponding damage weight and accumulated to obtain the damage degree assessment coefficient. The damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined according to the damage degree assessment coefficient.

[0027] A system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, for executing any of the above-mentioned methods for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, with reference to Figure 2 As shown, it includes a sample acquisition module, a data acquisition module, a degradation rate calculation module, a related factor determination module, a related factor prediction module, a degradation coefficient calculation module, a safety threshold calculation module, a damage degree preliminary judgment module and a damage degree assessment module connected in sequence; Sample acquisition module: prepare a certain number of fly ash / silica fume modified magnesium phosphate cement samples, and calcine them at different temperatures after curing to obtain calcined fly ash / silica fume modified magnesium phosphate cement samples; Data acquisition module: Analyze fly ash / silica fume modified magnesium phosphate cement samples calcined at different temperature ranges, and divide the pores into gel pores, fine capillary pores, medium capillary pores, large capillary pores, and macropores based on pore size. The operating temperature is divided into multiple temperature ranges, and the compressive strength, total porosity, and pore size ratio data of at least two fly ash / silica fume modified magnesium phosphate cement samples are obtained at the corresponding temperature in each temperature range. The pore size ratio of each pore is multiplied by the total porosity to generate gel pore porosity, small capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, and macropore porosity to obtain sample data; Deterioration rate calculation module: Construct a compressive strength prediction function including undetermined coefficients, and combine sample data to obtain the correction coefficient and degradation rate that vary with the action temperature as the undetermined coefficients; Correlation factor determination module: Determine the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement samples and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio and large pore size ratio data based on the sample data, and determine the correlation factor that is strongly correlated with the compressive strength based on the size of the correlation coefficient; Related factor prediction module: Filters data corresponding to related factors from sample data and establishes related factor prediction function based on cubic spline interpolation function technology; Deterioration coefficient calculation module: Obtain the total porosity and pore size ratio data of the same fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, thereby generating the porosity of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures. Based on the porosity, the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures is generated; Safety threshold calculation module: Determine the temperature range and degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample based on its working temperature, calculate the ratio between the degradation coefficient and the degradation rate, divide the above ratio into the temperature range corresponding to the relevant temperature, and determine the maximum value of the ratio of the degradation coefficient to the degradation rate in the temperature range as the safety threshold; Preliminary damage assessment module: This module obtains the total porosity, pore size ratio of each type of pore, and the operating temperature of the fly ash / silica fume modified magnesium phosphate cement to be evaluated. It then obtains the porosity, degradation coefficient, and degradation rate of each type of pore. It then calculates the ratio of the degradation coefficient to the degradation rate and compares it with the safety threshold. Damage degree assessment module: When the ratio is not greater than the safety threshold, the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after high temperature is considered normal. Otherwise, the damage degree coefficient used to measure the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples is calculated based on the correlation coefficient corresponding to the relevant factors and the difference in relevant factors between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples. The damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined based on the size of the damage degree assessment coefficient.

[0028] In a specific embodiment, A method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature treatment comprises the following steps: S1. Prepare a certain amount of fly ash / silica fume modified magnesium phosphate cement samples. The magnesium oxide used is magnesite calcined at high temperature and then ground, with an average particle size of 96.88 μm and an oxide composition as shown in Table 1. The potassium dihydrogen phosphate is industrial grade with a purity of >99.5%. The borax is analytical grade. The fly ash is Class I fly ash with an average particle size of 86.76 μm and an oxide composition as shown in Table 1. The silica fume has an average particle size of 13.74 μm and an oxide composition as shown in Table 1. The water is ordinary domestic water. Table 1 Oxide composition table According to the established formula, magnesium oxide, potassium dihydrogen phosphate, borax, fly ash, silica fume and water are placed in a blender according to the ratio shown in Table 2 and mixed thoroughly until a uniform state is achieved. After mixing, the MPC slurry is poured into a mold and placed on a vibration table. When there are no obvious bubbles on the surface of the specimen, it is demolded and placed in an indoor environment with a temperature of 20±5℃ and a humidity of 50±5℃ for curing. Table 2 Composition ratio table The data in Table 2 are in grams.

[0029] S2. Analyze fly ash / silica fume modified magnesium phosphate cement samples after calcination at different temperature intervals. Based on the pore size, the pores are divided into gel pores, fine capillary pores, medium capillary pores, large capillary pores, and macropores. The action temperature is divided into multiple temperature intervals. The compressive strength, total porosity, and pore size ratio of each type of pore are obtained for at least two fly ash / silica fume modified magnesium phosphate cement samples at the corresponding temperature in each temperature interval. The pore size ratio of each type of pore is multiplied by the total porosity to generate gel pore porosity, small capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, and macropore porosity to obtain sample data. S3. Establish a prediction function for the high-temperature compressive strength of fly ash / silica fume modified magnesium phosphate cement with an undetermined coefficient. The temperature range is divided into five temperature ranges: 20°C-105°C, 106°C-200°C, 201°C-400°C, 401°C-600°C, and 601-800°C. The corresponding prediction function expression for the compressive strength of fly ash / silica fume modified magnesium phosphate cement is as follows: , The above function is calculated to infer the unknown coefficients, and the final compressive strength prediction function is as follows: , Fly ash / silica fume modified magnesium phosphate cement will undergo melting and sintering at 600℃-800℃, and its compressive strength will increase. This phenomenon can also be reflected in the prediction function.

[0030] S4. Based on the sample data, the correlation coefficient between the compressive strength of the fly ash / silica fume modified magnesium phosphate cement sample and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio, and macropore size ratio is determined, and the correlation coefficient threshold is set. The correlation coefficients between the compressive strength of the fly ash / silica fume modified magnesium phosphate cement after being subjected to 600°C and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio, and macropore size ratio are shown in Table 3. Table 3 Correlation coefficient between compressive strength and proportion of different pore diameters The correlation threshold is set to 0.85, and the correlation coefficients between compressive strength and large capillaries and large pores are both greater than 0.85, while the correlation coefficients between compressive strength and gel pores, small capillaries, and medium capillaries are all less than 0.85. It can be seen that large capillaries and large pores are related factors related to compressive strength. Of course, the correlation threshold can also be set to other values, which will be set by technical personnel in this field according to actual conditions.

[0031] S5. The key factors are the large capillary pore size ratio and the large pore size ratio. The pore size ratio data of various types of pores collected in step S3 are screened out to obtain the large capillary pore size ratio and the large pore size ratio prediction function, so as to obtain the large capillary pore size ratio prediction function and the large pore size ratio prediction function. In this way, only the large capillary pore size ratio prediction function and the large pore size ratio prediction function that are strongly correlated with the compressive strength are calculated, without calculating the gel pore size ratio prediction function, the small capillary pore size ratio prediction function and the medium capillary pore size ratio prediction function that are weakly correlated with the compressive strength, thereby reducing the amount of calculation; Among them, the prediction function of the large capillary pore diameter ratio is as follows: in, It represents the proportion of large capillary pores in fly ash / silica fume modified magnesium phosphate cement after being exposed to an ambient temperature of T℃; The macropore diameter ratio prediction function is as follows: It represents the proportion of macropore size in fly ash / silica fume modified magnesium phosphate cement after being exposed to ambient temperature of T℃.

[0032] S6. Obtain data on the total porosity and pore size ratio of each type of pores of the same fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, thereby generating the gel pore porosity, fine capillary pore porosity, medium capillary pore porosity, large capillary pore porosity and macropore porosity of the sample after being subjected to different temperatures, and based on the above porosity, generate the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures.

[0033] S7. Determine the temperature range and degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample according to its operating temperature, calculate the ratio between the degradation coefficient and the degradation rate, divide the above ratio into the temperature range corresponding to the relevant temperature, and determine the maximum value of the ratio of the degradation coefficient to the degradation rate in the temperature range as the safety threshold.

[0034] S8. Obtain the total porosity, pore size ratio data of various pore types, and operating temperature of the fly ash / silica fume modified magnesium phosphate cement to be evaluated, obtain the porosity, degradation coefficient, and degradation rate of various pore types, calculate the ratio of the degradation coefficient to the degradation rate, and compare it with the safety threshold.

[0035] S9. When the ratio is greater than the safety threshold, the relevant factors are determined to include the large capillary pore size ratio and the large pore size ratio, and the damage weights corresponding to the large capillary pore size ratio and the large pore size ratio are calibrated as 、 ,by To constrain the compressive strength of fly ash / silica fume modified magnesium phosphate cement after high temperature, the correlation coefficients of large capillary pore size ratio and large pore size ratio are scaled proportionally to generate damage weights that correspond to large capillary pore size ratio and large pore size ratio. 、 ; The abnormal temperature range is marked as Ty c ,and The proportion of large capillary pores and the proportion of large pores of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after being subjected to abnormal temperature range are calibrated as 、 , the calculation formula of the damage degree assessment coefficient is as follows: , It should be noted that S(T yc ) It represents the damage degree evaluation coefficient of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after being subjected to the abnormal temperature range. After the abnormal temperature range, the relative errors of the relevant factor data in the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples are multiplied by the corresponding damage weights and then accumulated to obtain the damage degree evaluation coefficient. In this way, the influence of various relevant factors is comprehensively considered. The greater the difference in the relevant factor data between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples, the greater the pore structure deviation between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples, that is, the greater the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated, and the higher the damage degree evaluation coefficient. S(T yc ) The bigger it is; The damage degree level of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined based on the damage degree assessment coefficient. The specific standards are shown in Table 4 below: Table 4 Injury level assessment table When the damage degree assessment coefficient satisfies 0≤ S(T yc ) When the damage degree evaluation coefficient is less than 0.05, it indicates that the pore structure deviation between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement sample is small, and the deterioration degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is within the normal range. It is evaluated as normal damage and the fly ash / silica fume modified magnesium phosphate cement can be repaired and continued to be used. When the damage degree evaluation coefficient meets 0.05≤ S(T yc )When the value is less than 0.2, it indicates that the pore structure deviation between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement sample is large, and the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is general. It is assessed as general damage and needs to be repaired in time. In the future, the relevant data of the fly ash / silica fume modified magnesium phosphate cement to be evaluated should be monitored in real time. If it still does not meet the standards after repair, the fly ash / silica fume modified magnesium phosphate cement to be evaluated should be scrapped. When the damage degree assessment coefficient meets the requirements, the fly ash / silica fume modified magnesium phosphate cement to be evaluated should be scrapped. S(T yc ) When the value is ≥0.2, it indicates that the pore structure deviation between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement sample is too large, and the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is too large. It is evaluated as excessively damaged and the fly ash / silica fume modified magnesium phosphate cement to be evaluated is scrapped. The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, characterized in that: The following steps are involved: S1. preparing a certain number of fly ash / silica fume modified magnesium phosphate cement samples, curing them, and calcining them at different temperatures to obtain calcined fly ash / silica fume modified magnesium phosphate cement samples; S2. Analyze fly ash / silica fume modified magnesium phosphate cement samples after calcination at different temperature intervals. Based on the pore size, the pores are divided into gel pores, fine capillary pores, medium capillary pores, large capillary pores, and macropores. The operating temperature is divided into multiple temperature intervals. The compressive strength, total porosity, and pore size ratio of each type of pore are obtained for at least two fly ash / silica fume modified magnesium phosphate cement samples at the corresponding temperature in each temperature interval. The pore size ratio of each type of pore is multiplied by the total porosity to generate gel pore porosity, small capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, and macropore porosity to obtain sample data. S3. Construct a compressive strength prediction function including undetermined coefficients, and obtain the correction coefficient and degradation rate that vary with the action temperature as the undetermined coefficients based on the sample data; S4. Determine the correlation coefficient between the compressive strength of the fly ash / silica fume modified magnesium phosphate cement sample and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio, and large pore size ratio based on the sample data, and determine the relevant factors that are strongly correlated with the compressive strength based on the magnitude of the correlation coefficient; S5. Filtering data corresponding to relevant factors from the sample data, and establishing a relevant factor prediction function based on a cubic spline interpolation function technique; S6. Obtain data on the total porosity and pore size ratio of each type of porosity of the same fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, thereby generating the porosity of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, and based on the porosity, generate the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures; S7. Determine the temperature range and degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample according to its operating temperature, calculate the ratio between the degradation coefficient and the degradation rate, divide the above ratio into temperature ranges corresponding to the relevant temperatures, and determine the maximum value of the ratio of the degradation coefficient to the degradation rate in the temperature range as the safety threshold; S8. Obtain the total porosity, pore size ratio of each type of pore, and operating temperature of the fly ash / silica fume modified magnesium phosphate cement to be evaluated, obtain the porosity, degradation coefficient, and degradation rate of each type of pore, calculate the ratio of the degradation coefficient to the degradation rate, and compare it with the safety threshold; S9. When the ratio is not greater than the safety threshold, the degree of damage of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after high temperature is deemed normal. Otherwise, the damage degree coefficient used to measure the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples is calculated based on the correlation coefficient corresponding to the relevant factors and the difference in relevant factors between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples. The damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined based on the magnitude of the damage degree assessment coefficient. The curing and calcining in S1 includes curing in a room environment at a temperature of 20±5°C and a humidity of 50±5°C for 28 days and then moving the mixture into a muffle furnace for calcination.

2. The method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature according to claim 1, characterized in that: S3 includes: establishing a prediction function for the compressive strength of fly ash / silica fume modified magnesium phosphate cement samples after high temperature treatment, and the corresponding expression is: ， in, T represents the temperature number, and T =0℃、105℃、200℃、400℃、……、 t ℃, t Indicates the operating temperature, It means that fly ash / silica fume modified magnesium phosphate cement is T The compressive strength after action, T 1. T 2 、…、 T i 、…、 T n are all specific temperatures within the temperature range. i represents different temperature ranges, and i =1, 2, 3, ..., n , n is the total number of temperature intervals set in the test, and n ≤ T , ， 、 、 …、 、 …、 and 、 、 …、 、 …、 are all undetermined coefficients, and …、 …、 are the correction constants corresponding to different temperature ranges, …、 、 …、 are the degradation rates corresponding to different temperature ranges, and the compressive strength and corresponding action temperature collected from each fly ash / silica fume modified magnesium phosphate cement sample are substituted into the compressive strength prediction function to form the undetermined coefficient …、 …、 and …、 、 …、 The multivariate linear equation system is to ensure that the number of equations in the system is greater than the number of undetermined coefficients, and then the undetermined coefficients are solved based on the least squares method. …、 …、 and …、 、 …、 The solution is obtained and the unknown coefficients are inferred, thereby establishing a prediction function for the compressive strength of fly ash / silica fume modified magnesium phosphate cement.

3. The method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature according to claim 2, characterized in that: S4 includes: calculating the correlation coefficients between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of gel pores, the proportion of small capillary pores, the proportion of medium capillary pores, the proportion of large capillary pores and the proportion of large pores based on the Pearson correlation calculation formula; A correlation threshold is preset. When the correlation coefficient between compressive strength and gel pore diameter ratio is greater than the correlation threshold, the gel pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and small capillary pore diameter ratio is greater than the correlation threshold, the small capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and medium capillary pore diameter ratio is greater than the correlation threshold, the medium capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and large capillary pore diameter ratio is greater than the correlation threshold, the large capillary pore diameter ratio is determined as a related factor strongly correlated with the compressive strength. When the correlation coefficient between compressive strength and large pore diameter ratio is greater than the correlation threshold, the large pore diameter ratio is determined as a related factor strongly correlated with the compressive strength.

4. The method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature according to claim 3, characterized in that: The relationship between compressive strength and gel pore size ratio is expressed as: ， in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T Compressive strength after action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average compressive strength after the action, x is the number of the different fly ash / silica fume modified magnesium phosphate cement samples, and x =1, 2, 3..., X , X is the total number of fly ash / silica fume modified magnesium phosphate cement samples, and ; For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of gel pore size after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of the gel pores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of gel pore size; The expression of compressive strength and small pore size ratio is: ， in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of small capillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of fine capillaries after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of fine capillary pores; The expression of compressive strength and mesopore diameter ratio is: ， in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of mesocapillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of mesocapillaries after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of mesopores; The expression of compressive strength and the ratio of large pore diameter is: ， in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of large capillary pores after the action; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of large capillary pores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of large capillary pores; The expression of compressive strength and macropore diameter ratio is: ， in, For the x Fly ash / silica fume modified magnesium phosphate cement at a temperature of T The proportion of macropore diameter after the effect; for X Fly ash / silica fume modified magnesium phosphate cement at temperature T The average pore size ratio of macropores after the action; is the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement and the proportion of macropore size.

5. The method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature according to claim 4, characterized in that: The expression of the degradation coefficient in S5 is: in, KX z ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Total porosity after ℃ action; KX Gel ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T The porosity of the gel after ℃ action; KX Fin,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T The porosity of small capillary pores after the action of ℃; KX Med,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Mesocapillary porosity after ℃ action; KX Lar,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Macrocapillary porosity after ℃ action; KX Lar ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T Macroporosity after ℃ action; Z z ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the total porosity increases compared with the previous temperature range; Z Gel ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the porosity of the gel pores increases compared with the previous temperature range; Z Fin,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T After the action of ℃, the capillary porosity increases compared with the previous temperature range; Z Med,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the mesocapillary porosity increases compared with the previous temperature range; Z Lar,cap ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the macrocapillary porosity increases compared with the previous temperature range; Z Lar ( T ) indicates that the fly ash / silica fume modified magnesium phosphate cement sample is T ℃, the macropore porosity increases compared with the previous temperature range. Ygp ( T ) Fly ash / silica fume modified magnesium phosphate cement samples at ambient temperature T Deterioration coefficient after the action of ℃.

6. The method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature treatment according to claim 1, characterized in that: Determining the level of injury involves the following steps: The operating temperature at which the degradation coefficient and degradation rate ratio of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is greater than the safety threshold is determined as the abnormal temperature, and the number of related factors is determined; When the number of relevant factors is 1, calculate the relative error of the relevant factor data in the fly ash / silica fume modified magnesium phosphate cement and fly ash / silica fume modified magnesium phosphate cement samples to be evaluated after the abnormal temperature, and multiply the relative error by the correlation coefficient corresponding to the relevant factor to obtain the damage degree assessment coefficient; When the number of relevant factors is greater than 1, the correlation coefficients corresponding to each relevant factor are scaled proportionally, with the cumulative value equal to 1 as the constraint, to generate damage weights corresponding to each relevant factor. The relative errors of the relevant factors in the fly ash / silica fume modified magnesium phosphate cement and fly ash / silica fume modified magnesium phosphate cement samples to be evaluated after abnormal temperature are calculated, and the relative errors of each relevant factor are multiplied by the corresponding damage weight and accumulated to obtain the damage degree assessment coefficient. The damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined according to the damage degree assessment coefficient.

7. A system for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature, for executing the method for evaluating the degree of damage of fly ash / silica fume modified magnesium phosphate cement after high temperature according to any one of claims 1 to 6, characterized in that: It includes a sample acquisition module, a data acquisition module, a degradation rate calculation module, a related factor determination module, a related factor prediction module, a degradation coefficient calculation module, a safety threshold calculation module, a damage degree preliminary judgment module and a damage degree assessment module, which are connected in sequence; Sample acquisition module: prepare a certain number of fly ash / silica fume modified magnesium phosphate cement samples, and calcine them at different temperatures after curing to obtain calcined fly ash / silica fume modified magnesium phosphate cement samples; Data acquisition module: Analyze fly ash / silica fume modified magnesium phosphate cement samples calcined at different temperature ranges, and divide the pores into gel pores, fine capillary pores, medium capillary pores, large capillary pores, and macropores based on pore size. The operating temperature is divided into multiple temperature ranges, and the compressive strength, total porosity, and pore size ratio data of at least two fly ash / silica fume modified magnesium phosphate cement samples are obtained at the corresponding temperature in each temperature range. The pore size ratio of each pore is multiplied by the total porosity to generate gel pore porosity, small capillary pore porosity, medium capillary pore porosity, large capillary pore porosity, and macropore porosity to obtain sample data; Deterioration rate calculation module: Construct a compressive strength prediction function including undetermined coefficients, and combine sample data to obtain the correction coefficient and degradation rate that vary with the action temperature as the undetermined coefficients; Correlation factor determination module: Determine the correlation coefficient between the compressive strength of fly ash / silica fume modified magnesium phosphate cement samples and the gel pore size ratio, fine capillary pore size ratio, medium capillary pore size ratio, large capillary pore size ratio and large pore size ratio data based on the sample data, and determine the correlation factor that is strongly correlated with the compressive strength based on the size of the correlation coefficient; Related factor prediction module: Filters data corresponding to related factors from sample data and establishes related factor prediction function based on cubic spline interpolation function technology; Deterioration coefficient calculation module: Obtain the total porosity and pore size ratio data of the same fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures, thereby generating the porosity of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures. Based on the porosity, the degradation coefficient of the fly ash / silica fume modified magnesium phosphate cement sample after being subjected to different temperatures is generated; Safety threshold calculation module: Determine the temperature range and degradation rate of the fly ash / silica fume modified magnesium phosphate cement sample based on its working temperature, calculate the ratio between the degradation coefficient and the degradation rate, divide the above ratio into the temperature range corresponding to the relevant temperature, and determine the maximum value of the ratio of the degradation coefficient to the degradation rate in the temperature range as the safety threshold; Preliminary damage assessment module: This module obtains the total porosity, pore size ratio of each type of pore, and the operating temperature of the fly ash / silica fume modified magnesium phosphate cement to be evaluated. It then obtains the porosity, degradation coefficient, and degradation rate of each type of pore. It then calculates the ratio of the degradation coefficient to the degradation rate and compares it with the safety threshold. Damage degree assessment module: When the ratio is not greater than the safety threshold, the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated after high temperature is considered normal. Otherwise, the damage degree coefficient used to measure the damage degree of the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples is calculated based on the correlation coefficient corresponding to the relevant factors and the difference in relevant factors between the fly ash / silica fume modified magnesium phosphate cement to be evaluated and the fly ash / silica fume modified magnesium phosphate cement samples. The damage degree grade of the fly ash / silica fume modified magnesium phosphate cement to be evaluated is determined based on the size of the damage degree assessment coefficient.

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