High-toughness modified epoxy resin repair material based on mass-price ratio and optimization method thereof

Abstract

The invention discloses a high-toughness modified epoxy resin repair material based on a mass-to-price ratio and an optimization method of the high-toughness modified epoxy resin repair material. The material comprises superfine cement, kaolin, water, epoxy resin, an epoxy resin curing agent, a silane coupling agent, a defoaming agent, starch phosphate and polyurea. The high-toughness modified epoxy resin repair material has no bleeding phenomenon, the fluidity is greater than 12.5 cm, the three-day breaking strength is greater than 9 MPa, the compressive strength is greater than 20 MPa, and the bending-compression ratio is greater than 0.43; the folding and pressing ratio of 28 days ranges from 0.47 to 0.56; the improved sustainable potential index of the optimal ratio is greater than 2.0. The mechanical comprehensive performance of the microstructure is higher, the established improved sustainable potential index can effectively reflect the mass-price ratio of the novel material, the established ratio optimization formula simultaneously reflects the economical efficiency and the mechanical performance, the mechanical performance is improved for the repairing material of the tunnel lining structure, and the application prospect is wide. And in addition, construction operations such as mixing, stirring, smearing and vibrating are more convenient, and good market prospects are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel lining micro-crack repair material preparation, and particularly relates to a high-toughness modified epoxy resin repair material based on cost-performance ratio and an optimization method thereof. BACKGROUND

[0002] Compared with pure cement materials, epoxy resin cement-based materials have excellent toughness, which is manifested in the significant increase in the flexural strength. However, such materials have deficiencies in the early strength, and the increase in the flexural strength performance is often accompanied by the loss of the compressive strength. Meanwhile, as a repair material, due to the fast curing characteristics of the epoxy resin, the mixed material must be completed within the specified workable time, otherwise the material will gradually lose the fluidity. In addition, the adhesion between the traditional epoxy resin cement-based material and the concrete is not good, which is difficult to guarantee the crack repair construction quality.

[0003] The silane coupling agent can realize the coupling between organic-inorganic or organic-organic materials to improve the performance of the repair material. The starch phosphate molecule contains hydrophilic and hydrophobic groups, which can improve the water retention, thickening and internal adhesion of the material. The polyurea is known for its good flexibility and high strength, and the fibrous structure formed in the material can enhance the toughness and effectively prevent the expansion of the cracks, thereby improving the tensile and impact resistance of the material. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-toughness modified epoxy resin repair material based on cost-performance ratio and an optimization method thereof. The high-toughness modified epoxy resin repair material has no bleeding phenomenon, the fluidity is greater than 12.5 cm, the 3-day flexural strength is greater than 9 MPa, the compressive strength is greater than 20 MPa, and the flexural-compressive ratio is greater than 0.43. The flexural-compressive ratio of 28 days is between 0.47 and 0.56. The improved sustainability potential index of the optimal ratio is greater than 2.0. The mechanical comprehensive performance of the microstructure is higher, the improved sustainability potential index can effectively reflect the cost-performance ratio of the new material, and the ratio optimization formula reflects the economy and mechanical performance at the same time, which has good market prospects.

[0005] To solve the problems in the prior art, the technical scheme adopted by the present application is as follows:

[0006] The application discloses a high-toughness modified epoxy resin repairing material based on quality-price ratio, which comprises the following components: superfine cement, kaolin, water, water-based epoxy resin, epoxy resin curing agent, silane coupling agent, defoaming agent, starch phosphate and polyurea, wherein the superfine cement and the kaolin are mixed into dry materials, the ratio of water-based epoxy resin to dry materials is 1:1.2, the water-cement ratio is 0.24, the kaolin accounts for 30% of the dry material, the silane coupling agent accounts for 0.25% of the mass of the water-based epoxy resin, the mass ratio of the water-based epoxy resin to the epoxy resin curing agent is 1:1.5, the epoxy resin emulsion is a mixture of the epoxy resin and the epoxy resin curing agent, the defoaming agent accounts for 1% of the mixing amount of the epoxy resin emulsion, the starch phosphate accounts for 2.5%-10% of the mixing amount of the superfine cement, and the polyurea accounts for 0.25%-1% of the mass of the epoxy resin emulsion.

[0007] As an improvement, the silane coupling agent is silane coupling agent Kh550.

[0008] As an improvement, the defoaming agent is a silicone defoaming agent.

[0009] As an improvement, the mixing amount of the starch phosphate is 2.5% of the mixing amount of the superfine cement.

[0010] Further improvement, the mixing amount of the polyurea is 0.25% of the mass of the epoxy resin emulsion.

[0011] The above-mentioned high-toughness modified epoxy resin repairing material based on quality-price ratio is prepared by the following method: weighing the superfine cement, the kaolin, the water, the epoxy resin, the epoxy resin curing agent, the silane coupling agent, the defoaming agent, the starch phosphate and the polyurea; slowly and uniformly mixing the superfine cement and the kaolin for 2 minutes to obtain cement fillers; slowly stirring the epoxy resin and the epoxy resin curing agent in a beaker until uniform, then adding the water and the defoaming agent and stirring for 2 minutes to obtain a mixture; adding the mixture into the cement fillers and stirring until uniform, then adding the silane coupling agent and stirring until uniform and without lumping, and then adding the polyurea and continuously stirring until uniform to obtain modified cement grout.

[0012] Step 1, according to the content of starch phosphate, set multiple starch phosphate experimental groups and no starch phosphate as the starch phosphate reference group, wherein the starch phosphate experimental group contains ultra-fine cement, kaolin, water, water-based epoxy resin, epoxy resin curing agent, silane coupling agent, defoamer and polyurea, the amount of other components is the same among the experimental groups; according to the content of polyurea, set multiple polyurea experimental groups and polyurea reference group without polyurea, wherein the polyurea experimental group contains ultra-fine cement, kaolin, water, water-based epoxy resin, epoxy resin curing agent, silane coupling agent, defoamer and starch phosphate, the amount of other components is the same among the experimental groups except polyurea, and the same as in the starch phosphate experimental group; prepare the repair material for each experimental group and each reference group, and test the flexural strength and compressive strength of the repair material at the corresponding age of 3 days, 7 days and 28 days; finally, prepare a group of concrete without starch phosphate and polyurea as the control group according to the same content;

[0013] Step 2, fit the 28d flexural strength and compressive strength of the starch phosphate and polyurea test groups, and the fitting formula of the flexural strength is as follows:

[0014]

[0015] Wherein, x represents the content of starch phosphate, unit is %; y represents the content of polyurea, unit is %, f kz is the flexural strength;

[0016] The R 2 of the fitting surface corresponding to the flexural strength is 0.8721, the fitting degree is higher, and the influence of starch phosphate and polyurea on the flexural strength of the modified material is accurately simulated;

[0017] Take the partial derivative of x and y in the fitting formula of the flexural strength respectively:

[0018]

[0019] To make the flexural strength reach the extreme value, the partial derivative is taken 0, and the stationary point (3.87, 0.32) is obtained. The stationary point (3.87, 0.32) is the maximum value point of the function, and the corresponding maximum flexural strength is 14.06MPa; that is, when the content of starch phosphate is 3.87% of the content of ultra-fine cement, and the content of polyurea is 0.32% of the mass of epoxy resin emulsion, the flexural strength of the modified material reaches the best value of 14.06MPa, the corresponding compressive strength is 27.425MPa, and the flexural compressive ratio is 0.513, which is 241.7% higher than the flexural compressive ratio of C30 concrete; the flexural strength prediction equation established based on the fitting method can obtain the optimal proportion under the consideration of the flexural strength index by the derivation method;

[0020] The fitting formula of the compressive strength is:

[0021]

[0022] Wherein, x represents the starch phosphate content, unit is %; y represents the polyurea content, unit is %;

[0023] The R of the fitting surface corresponding to the compressive strength is 2 =0.9735, the fitting degree is very high, and the influence of starch phosphate and polyurea on the compressive strength of the modified material can be accurately simulated;

[0024] The partial derivative of x and y in the fitting formula of the compressive strength is:

[0025]

[0026] When the partial derivative is 0, the stationary point (2.83, 0.34) is obtained, and the second-order partial derivative discriminant is used to determine whether the stationary point is an extreme point, and the stationary point (2.83, 0.34) is the maximum value point of the function, and the corresponding maximum compressive strength is 27.81 MPa; that is, when the starch phosphate content is 2.83% of the super-fine cement content and the polyurea content is 0.34% of the mass of the epoxy resin emulsion, the maximum compressive strength of the modified material is 27.81 MPa, and the corresponding flexural strength is 13.98 MPa; the prediction equation of the compressive strength established based on the fitting method can obtain the optimal ratio considering the compressive strength index, that is, the starch phosphate content of the modified epoxy resin repair material is in the optimal range of 2.83% to 3.87% of the super-fine cement content, and the polyurea content is in the range of 0.32% to 0.34% of the mass of the epoxy resin emulsion, and the comprehensive performance is good;

[0027] Step 3, calculate the cost sustainability potential index K S of different groups set in step 1; according to the test method of starch phosphate, the initial potential index value K S,0 and the sustainability potential index K S considering the flexural-compressive ratio of the modified material prepared by polyurea are calculated, and the calculation formula is as follows:

[0028]

[0029]

[0030] Wherein, K S,0 is the initial potential index value, K S is the sustainability potential index considering the flexural-compressive ratio, f kz and f kyrespectively represent the flexural strength and compressive strength, E represents the economic cost of the concrete material, L represents the flexural-compressive ratio of the material, and the ref subscript represents the reference concrete, and the non-subscript represents the researched concrete;

[0031] The greater the value of the sustainability potential index, the better the performance of the group of concrete materials, with good durability, strong sustainability and cost economy, which can meet the requirements of different application scenarios for different strength grades;

[0032] According to the existing market price a of the material, the cost is calculated by the following formula:

[0033] E = a + 0.035x + 1.031y

[0034] Wherein, a represents the existing market price, x represents the ratio of the starch phosphate ester content to the content of the super fine cement, %; y represents the ratio of the polyurea content to the mass of the epoxy resin emulsion, %;

[0035] Substitute the cost calculation formula into the sustainability potential index Ks, so the considered flexural-compressive ratio of the starch phosphate ester and polyurea modified repair material is

[0036]

[0037] The 28d flexural strength of the original group without adding starch phosphate ester and polyurea is 13.7MPa, the 28d compressive strength is 24.3MPa, the flexural-compressive ratio is 0.564, and the corresponding original sustainability potential index K S is 2;

[0038] According to step 2, the maximum flexural strength is 14.06MPa; that is, the starch phosphate ester content is 3.87% of the content of the super fine cement, the polyurea content is 0.32% of the mass of the epoxy resin emulsion, the corresponding compressive strength of the modified material is 27.425MPa, and the flexural-compressive ratio is 0.513; At this time, the corresponding sustainability potential index K S is 2.065, which indicates that the ratio has improved when the economic cost, flexural strength, compressive strength and flexural-compressive ratio of the repair material are considered comprehensively;

[0039] According to step 2, the maximum compressive strength is 27.81MPa; that is, the starch phosphate ester content is 2.83% of the content of the super fine cement, the polyurea content is 0.34% of the mass of the epoxy resin emulsion, the corresponding flexural strength of the modified material is 13.98MPa, and the flexural-compressive ratio is 0.503; At this time, the corresponding sustainability potential index K S is 2.047, which indicates that the ratio has improved compared with the original group when the economic cost, flexural strength, compressive strength and flexural-compressive ratio of the repair material are considered comprehensively;

[0040] The sustainability potential index KS The formula (i.e. objective function) is extremum, usually partial derivative is carried out, i.e. according to mathematical definition, the condition that the sustainable potential index Ks can take extremum is that the partial derivative is 0, and the two equations are equal to 0, so that the optimal ratio based on the sustainable potential index considering the compressive strength, the bending strength and the economy can be obtained.

[0041] The application of the high-toughness modified epoxy resin repair material based on the cost-performance ratio in the repair of micro-cracks of tunnel lining.

[0042] Beneficial effects:

[0043] The physical indexes of setting time, bleeding rate and fluidity and the mechanical properties of bending strength, compressive strength and bending-compressive strength ratio are comprehensively considered, the physical and chemical properties of various components are comprehensively considered, the epoxy resin cement-based material is improved to improve the performance of the micro-crack repair material of the tunnel lining, the modified repair material ratio meeting the micro-crack of the tunnel lining is developed, the effects of the two raw materials of starch phosphate and polyurea are focused on, the single factor analysis method is used to optimize the ratio, the theoretical prediction formula of the optimized ratio based on the cost-performance ratio is proposed, and the ratio optimization method considering the economy is proposed, which provides a ratio optimization theoretical basis for the application of actual engineering and is more convenient for popularization and application.

[0044] 1. The setting and final setting time of the starch phosphate ester incorporated extension material is prolonged, and the bleeding rate is reduced. The fluidity of the modified test is 12.5-17.5 cm, which meets the requirements of the tunnel repair material. With the increase of the starch phosphate ester content, the bending strength first increases and then decreases, and the suitable content range is 2.5%-5.0% of the ultra-fine cement, and the bending strength decreases when the content exceeds 5%; the influence on the compressive strength is also increased first and then decreased with the increase of the content, and the compressive strength reaches the maximum value of 27.7 MPa after 28d of curing at the content of 2.5%, which is increased by 8.2% compared with the blank group, the bending strength is 13.8 MPa, which is increased by 2.98% compared with the blank group, and the bending-compressive strength ratio is 0.498; the starch phosphate ester molecule contains hydrophilic and hydrophobic groups, which can improve the water retention, thickening and internal adhesion of the material; the polyurea is known for its good flexibility and high strength, and the fibrous structure formed in the material can enhance the toughness and effectively prevent the expansion of cracks, and improve the tensile and impact properties of the material.

[0045] 2、Polyurea incorporation shortened the modified repair material setting time, the flow degree was still greater than 13 cm, met the repair requirement, the material was without weeping phenomenon.The flexural strength increased first and then decreased with the increase of polyurea content, when the polyurea content accounted for 0.25% of the mass of epoxy resin emulsion, reached the peak value 13.5MPa after 28d curing, the flexural strength was lower than the blank group when more than 0.75%.Within the range of 0-1.0% of the polyurea content accounted for the mass of epoxy resin emulsion, the compressive strength also increased first and then decreased, reached the maximum value when the polyurea content accounted for 0.25%, the compressive strength was 27.7MPa, increased by 6.13% compared with the blank group.Introducing starch phosphate and polyurea into the silane modified epoxy resin cement-based material can improve the repair performance of the material and meet the demand of complex working conditions of tunnel engineering.

[0046] 3、According to the test results, the fitting plane of the starch phosphate and polyurea content about the flexural and compressive strength was established respectively, and the extreme value of the flexural and compressive strength was predicted through the fitting equation: when the starch phosphate accounted for 3.87% of the superfine cement and the polyurea accounted for 0.32% of the mass of the epoxy resin emulsion, the flexural strength was the maximum 14.06MPa, the corresponding compressive strength was 27.425MPa, the flexural-compressive ratio was 0.513, which was increased by 241.7% compared with the flexural-compressive ratio of C30 concrete; when the starch phosphate accounted for 2.83% of the superfine cement and the polyurea accounted for 0.34% of the mass of the epoxy resin emulsion, the compressive strength of the modified material was the maximum 27.81MPa, the corresponding flexural strength was 13.98MPa, the flexural-compressive ratio was 0.503, which was increased by 235.3% compared with the flexural-compressive ratio of C30 concrete;

[0047] 4、The starch phosphate in the modified epoxy resin repair material of the present application forms a unique network and honeycomb structure, increases the water retention, promotes the cement hydration reaction to proceed fully, and the material is more tightly bonded inside; the polyurea forms a long fibrous structure, uniformly distributed in the material, enhances the overall performance of the material, and effectively prevents the generation and development of cracks. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Flexural strength of starch phosphate group;

[0049] Figure 2 Compressive strength of starch phosphate group;

[0050] Figure 3 Flexural strength of polyurea group;

[0051] Figure 4 Compressive strength of polyurea group;

[0052] Figure 5 Improved sustainability potential index K of starch phosphate group S Graph;

[0053] Figure 6 Improved sustainability potential index K for polyurea group S Graphs;

[0054] Figure 7 Fitting graph for flexural strength of starch phosphate and polyurea modified materials;

[0055] Figure 8 Fitting graph for compressive strength of starch phosphate and polyurea modified materials;

[0056] Figure 9 SEM electron microscope morphology graph for C0 group;

[0057] Figure 10 SEM electron microscope morphology graph for D1 group;

[0058] Figure 11 SEM electron microscope morphology graph for D2 group. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0060] A preparation method of a high-toughness modified epoxy resin repair material based on cost-performance ratio, comprising the following steps:

[0061] (1) respectively weigh the ultra-fine cement, kaolin, water, epoxy resin, epoxy resin curing agent, silane coupling agent, defoaming agent, starch phosphate and polyurea;

[0062] (2) slowly dry-mix the ultra-fine cement and kaolin for 2 min, and mix uniformly to obtain a cement filler;

[0063] (3) pour the epoxy resin and epoxy resin curing agent into a beaker and slowly stir until uniform, then add water and defoaming agent and stir for 2 min to obtain a mixture;

[0064] (4) pour the mixture into the cement filler and stir uniformly, then add the silane coupling agent and stir until uniform and free of lumps, then add the polyurea and continuously stir uniformly to obtain a modified cement neat paste.

[0065] The test method of the repair material is as follows: the modified cement neat paste is sent into a 40mm*40mm*160mm test mold, and after being fully tamped and vibrated, it is scraped flat and the air bubbles are removed, then after 24h, the test block is taken out and sent into a curing box with a relative humidity greater than 95% and a temperature of 20℃ for curing to the corresponding age.

[0066] Example 1 Influence of starch phosphate content on the mechanical properties of modified epoxy resin repair materials

[0067] The starch phosphate used in the present application is a hydroxypropyl starch phosphate produced by Henan Zhongchen Biotechnology Co., Ltd., which is white powder in appearance, odorless and tasteless, easily soluble in water, and insoluble in organic solvents. It is commonly used as a thickening agent in the food processing field. The swelling power and transparency of the starch phosphate are significantly higher than those of ordinary starch, and the paste obtained after dissolving in water has high stability to temperature, acidity and shear force.

[0068] The group C0 ratio: ultra-fine cement 854.66 g, kaolin 337.89 g, water 308.07 g, epoxy resin 993.79 g, epoxy resin curing agent 1490.69 g, silane coupling agent Kh550 4.97 g, and silicone defoaming agent 9.94 g. Using single factor analysis method, on the basis of the group C0 ratio, taking the starch phosphate content as the variable, setting the polyurea content as 0.25% of the waterborne epoxy resin content, i.e. 6.21 g, and the remaining raw material ratio as shown in Table 1, the effect of starch phosphate on the setting time, bleeding rate, flexural strength and compressive strength of silane modified high epoxy resin repair material was explored, and the test methods were as follows: "Concrete Admixture Homogeneity Test Method" (GB / T 8077-2023), "Cement Standard Consistency Water Content, Setting Time and Stability Test Method" (GB / T 1346-2024), "Highway Engineering Cement and Cement Concrete Test Procedures" (JTG 3420-2020), "Cement Mortar Strength Test Method (ISO Method)" (GB / T 17671-2021), and the results are shown in Table 2.

[0069] Table 1 Test raw material ratio of starch phosphate groups

[0070]

[0071] Table 2 Test results of starch phosphate groups

[0072]

[0073] From the test result data in Table 2 above, compared with the blank group with 0 starch phosphate content, the initial setting time of the groups with 2.5%, 5%, 7.5% and 10% starch phosphate content based on the ultra-fine cement content was extended by 12.5%, 12.5%, 20% and 25% respectively, while the final setting time was extended by 11.1%, 11.1%, 11.1% and 22.2% respectively, which indicates that the starch phosphate prolongs the initial and final setting time of the modified material, which not only increases the hydration reaction time of the cement-based material, but also increases the time of penetrating into the cracks, thereby enhancing the repair effect.

[0074] For the tiny cracks on the surface of the tunnel lining, the new material particle is less than 20 μm, the optimized flow degree of the repair material can exceed 12.5 cm, the initial setting time is long, and the material can smoothly penetrate into the deep crack to achieve the repair effect. At the same time, the incorporation of starch phosphate can reduce the bleeding rate of the modified material, and the bleeding rate of the test group is 0%, and no water is emitted during the test.

[0075] According to the influence curve of starch phosphate on the flexural strength and compressive strength of the silane modified high epoxy resin repair material Figures 1-2 When the starch phosphate is incorporated in an appropriate amount (the amount is 0-5% of the mass of the ultra-fine cement), the flexural and compressive strengths of the modified material can be enhanced, and the mechanical properties of the material are improved.

[0076] With the increase of the amount of starch phosphate, the flexural strength of the three ages presents the rule of first rising and then falling. At the curing ages of 3d and 7d, the flexural strength of the modified material reaches the peak value when the amount of starch phosphate is 2.5% of the mass of the ultra-fine cement, and the flexural strength of 3d and 7d is increased by 16.3% and 7.4% respectively compared with the original control group. When the sample is cured to 28d, the peak value is 5.0% of the mass of the ultra-fine cement, and the flexural strength is increased by 8.2% compared with the group without starch phosphate. Therefore, for the silane modified high epoxy resin repair material, the best amount of starch phosphate is not more than 5.0% of the mass of the ultra-fine cement.

[0077] As for the compressive strength of the silane modified high epoxy resin repair material, the compressive strength of the three ages first increases and then decreases when the amount of starch phosphate is 0-10.0% of the mass of the ultra-fine cement, and the maximum value of the compressive strength is reached at 2.5%, and the compressive strength of 3d, 7d and 28d is increased by 21.6%, 12.2% and 8.2% respectively compared with the blank group. Especially at the curing age of 3d, the incorporation of starch phosphate can improve the early strength of the silane modified high epoxy resin repair material. The starch phosphate particles can fill the voids between the cement particles, especially in the early stage when the cement hydration products have not fully filled the pores, and its incorporation makes the microstructure of the material more dense, which helps to improve the early bearing capacity of the material and builds a relatively stable skeleton for the early strength.

[0078] Therefore, for the silane modified high epoxy resin repair material of the present application, the incorporation of starch phosphate can improve the flow degree, bleeding rate, flexural and compressive strengths of the material, and the appropriate amount is 0-10% of the mass of the ultra-fine cement, and the best mechanical property ratio is that the amount of starch phosphate is 0.25% of the mass of the ultra-fine cement.

[0079] Example 2 Influence of polyurea content on the mechanical properties of the modified epoxy resin repair material

[0080] The aspartic pure polyurea used in the present application is produced by Shenzhen Gaodun New Material Co., Ltd. The performance of this aspartic pure polyurea is that the viscosity is 1300±16 8CPS, the flash point is 90±3℃, the adhesion is 10.5MPa / kg, the elongation at break is 300%~400%, and the tensile strength is greater than 15MPa.

[0081] The C0 group has the following proportions: ultra-fine cement 854.66g, kaolin 337.89g, water 308.07g, epoxy resin 993.79g, epoxy resin curing agent 1490.69g, silane coupling agent Kh550 4.97g, and silicone defoaming agent 9.94g. Using the single factor analysis method, with the polyurea dosage as the variable, the starch phosphate dosage is set to 2.5% of the ultra-fine cement, i.e. 21.37g, and the remaining raw material proportions are as shown in Table 3, to explore the influence of polyurea incorporation on the setting time, bleeding rate, flexural strength and compressive strength of the silane-modified high epoxy resin repair material. The test methods are as follows: “Concrete Admixture Homogeneity Test Method” (GB / T 8077-2023), “Cement Standard Consistency Water Content, Setting Time, and Stability Test Method” (GB / T 1346-2024), “Highway Engineering Cement and Cement Concrete Test Procedures” (JTG 3420-2020), “Cement Mortar Strength Test Method (ISO Method)” (GB / T 17671-2021), and the results are shown in Table 4.

[0082] Table 3: Test Raw Material Proportions of Polyurea Groups

[0083]

[0084] Table 4: Test Results of Polyurea Groups

[0085]

[0086] From Table 4, the dosage of polyurea is 0.25%, 0.50%, 0.75%, and 1.00% of the mass of the epoxy resin emulsion, compared with the blank test group without adding polyurea, the initial setting time is reduced by 0%, 3.3%, 7.1%, and 7.1% respectively, and the final setting time is reduced by 0%, 11.1%, 11.1%, and 11.1% respectively. This is because the addition of polyurea can accelerate the curing reaction of the epoxy resin in the repair material, accelerate the formation of gel, and shorten the setting time of the modified repair material. Compared with the control group, the addition of polyurea in the modified repair material does not change the flowability of the test group, and there is no bleeding phenomenon.

[0087] From Figure 3It can be seen that the polyurea can greatly improve the flexural strength of the new material when it is incorporated in an appropriate amount. Within the range of 0-1.0% of the mass ratio of polyurea to epoxy resin emulsion, the flexural strength increases first and then decreases with the increase of the polyurea content, and the peak value is obtained when the mass ratio of polyurea to epoxy resin emulsion is 0.25%. The flexural strength of 3d, 7d and 28d is increased by 9.2%, 12.5% and 8.9% compared with the blank control group. However, when the polyurea content exceeds 0.75% of the mass ratio of epoxy resin emulsion, the flexural strength performance starts to decrease compared with the blank group. For the modified material of the present application, the polyurea content is not suitable to be increased.

[0088] The law of the compressive strength of the modified repair material by polyurea is similar to that of the flexural strength. Within the range of 0-1.0% of the mass ratio of polyurea to epoxy resin emulsion, the three-month compressive strength increases first and then decreases with the increase of the polyurea content, and the peak value is obtained when the mass ratio of polyurea to epoxy resin emulsion is 0.25%. However, the improvement of the compressive strength is not as great as that of the flexural strength. The compressive strength is increased by 2.5%, 2.8% and 6.1% compared with the group without polyurea. When the polyurea content continues to increase, the compressive strength of the three ages decreases from the peak value, and when the mass ratio of polyurea to epoxy resin emulsion exceeds 5%, the compressive strength is lower than that of the blank control group.

[0089] The active groups in polyurea can react with the active groups on the surface of the matrix material to form chemical bonds. In addition, the good wettability of polyurea makes the modified material adhere to the surface of the matrix. Polyurea is a material with good flexibility and elasticity. When the repair material is impacted by external force, polyurea can absorb and disperse energy, just like an elastic buffer in the epoxy resin matrix. Therefore, the incorporation of polyurea improves the bonding performance between the repair material and the matrix material, and can improve the mechanical properties of the repair material.

[0090] In summary, to make the new repair material have good flexural and compressive strength, while taking into account the performance of setting time, fluidity and bleeding rate, the mass ratio of polyurea to epoxy resin emulsion should be in the range of 0-1%, and the best ratio is that the mass ratio of polyurea to epoxy resin emulsion is 0.25%.

[0091] Example 3 Comprehensive evaluation of modified epoxy resin repair material based on improved sustainability potential index

[0092] 1. The improved sustainability potential index is used to evaluate the single-factor test groups of starch phosphate.

[0093] In this test, the D0 group is set as the reference concrete group. The price of starch phosphate is 16.2 yuan / kg, and the price of polyurea is 166 yuan / kg. The unit price of the starch phosphate test groups is shown in Table 5.

[0094] Table 5 Starch phosphate group K S value

[0095]

[0096] The improved sustainability potential index (i.e. taking into account the reduction-to-pressure ratio) is calculated using the following formula.

[0097]

[0098] Among them, f kz and f ky represent flexural strength and compressive strength respectively, E represents the economic cost of concrete material, L represents the flexural-compressive ratio of the material, the ref subscript represents the reference concrete, and no subscript represents the concrete being studied.

[0099] Modified materials with the increase of starch phosphate materials, the sustainability potential index K of material improvement S It increases first and then decreases, and when the dosage is 5%, K S The maximum value is 2.230, which is 11.5% higher than the reference group D0. The trend of KS considering the compression ratio is also rising and then falling with the increase of dosage. The peak value is obtained when the starch phosphate dosage is 5%, which is 16.6% higher than the D0 group. S The values ​​of are greater than those without consideration, which indicates that the addition of starch phosphate increases the flexural strength and the toughness of the material. Figure 5 shown.

[0100] 2. The sustainability potential index of the polyurea group was calculated in the same way, with group J0 being used as the reference concrete group. The specific results are shown in Table 6 below.

[0101] Table 6 Polyurea Group K S value

[0102]

[0103] Sustainability potential index K of polyurea group improvement S The values ​​are similar to the changing trends of flexural and compressive strength in the single factor test. Figure 1 The results show that the urea content increases first and then decreases with the increase of polyurea content, and the peak value is obtained when the polyurea content is 0.25%.

[0104] When the polyurea content is 2.5%, the K S The value is 2.269, which is 13.45 higher than that of the reference group; considering the K S The value is 2.328, which is 16.4% higher than the reference group. After considering the discount ratio, the sustainability potential index K SAll are higher than the working condition without considering the fold pressure ratio, and the polyurea can improve the fold pressure ratio of the modified repair material. The results are shown in Figure 6 .

[0105] 3. The 28d flexural strength and compressive strength of the starch phosphate and polyurea test groups were fitted, and the results are shown in Figures 7-8 .

[0106] The fitting formula for flexural strength is

[0107]

[0108] where x represents the starch phosphate content, and y represents the polyurea content. kz

[0109] The R 2 of the fitting surface corresponding to the flexural strength is 0.8721, and the fitting degree is high, which can better simulate the effect of starch phosphate and polyurea on the flexural strength of the modified material.

[0110] The partial derivatives of x and y in the fitting formula for flexural strength are

[0111]

[0112] To get the extreme value of flexural strength, the partial derivative is taken to be 0, and the stationary point (3.87, 0.32) is obtained. Using the second-order partial derivative discriminant to determine whether the stationary point is an extreme point, it is found that the stationary point (3.87, 0.32) is the maximum point of the function, and the corresponding maximum flexural strength is 14.06 MPa. That is, when the starch phosphate content is 3.87% of the super-fine cement content and the polyurea content is 0.32% of the mass of the epoxy resin emulsion, the flexural strength of the modified material is best, which is 14.06 MPa, and the corresponding compressive strength is 27.425 MPa, and the fold pressure ratio is 0.513, which is 241.7% higher than the fold pressure ratio of C30 concrete.

[0113] The fitting formula for compressive strength is

[0114]

[0115] where x represents the starch phosphate content, and y represents the polyurea content.

[0116] The R 2 of the fitting surface corresponding to the compressive strength is 0.9735, and the fitting degree is very high, which can accurately simulate the effect of starch phosphate and polyurea on the compressive strength of the modified material.

[0117] Similarly, the partial derivatives of x and y in the fitting formula for compressive strength are ​

[0118]

[0119] The partial derivative is 0, and the stationary point (2.83, 0.34) is obtained. The second-order partial derivative discriminant is used to determine whether the stationary point is an extreme point, and it is found that the stationary point (2.83, 0.34) is the maximum value point of the function, and the maximum compressive strength is 27.81 MPa. That is, when the starch phosphate content is 2.83% of the super-fine cement content and the polyurea content is 0.34% of the mass of the epoxy resin emulsion, the maximum compressive strength of the modified material is 27.81 MPa, the corresponding flexural strength is 13.98 MPa, the flexural-compressive ratio is 0.503, and the flexural-compressive ratio of C30 concrete with a compressive strength of 30 MPa is 0.15, which is increased by 235%.

[0120] In summary, the starch phosphate content of the modified epoxy resin repair material in the application is in the optimized range of 2.83% to 3.87% of the super-fine cement content, and the polyurea content is in the range of 0.32% to 0.34% of the mass of the epoxy resin emulsion. When the material has a high quality-price ratio and good comprehensive performance.

[0121] According to the improved sustainability potential index The reference concrete group is the C0 group (not mixed with starch phosphate and polyurea), the economic cost is 18.411 yuan / kg, the 28d flexural strength is 13.7 MPa, and the compressive strength is 24.3 MPa. The cost of the modified material based on the C0 group is

[0122] E = a + 0.035x + 1.031y

[0123] Wherein, x represents the starch phosphate content as a percentage of the super-fine cement content, and y represents the polyurea content as a percentage of the mass of the epoxy resin emulsion.

[0124] Therefore, the sustainability potential index of the starch phosphate and polyurea modified repair material is

[0125]

[0126] Through calculation, the 28d flexural strength of the original group without mixing starch phosphate and polyurea is 13.7 MPa, the 28d compressive strength is 24.3 MPa, and the flexural-compressive ratio is 0.564. The corresponding original sustainability potential index K S The value is 2; the maximum flexural strength in step 2 is 14.06 MPa; that is, the starch phosphate content is 3.87% of the super-fine cement content, the polyurea content is 0.32% of the mass of the epoxy resin emulsion, the corresponding compressive strength of the modified material is 27.425 MPa, and the flexural-compressive ratio is 0.513; at this time, the corresponding sustainability potential index K S2.065, which indicates that the ratio is improved when the economic cost, flexural strength, compressive strength and flexural compressive ratio of the repair material are considered comprehensively; the maximum compressive strength obtained in step 2 is 27.81 MPa; that is, when the starch phosphate content is 2.83% of the content of the super-fine cement and the polyurea content is 0.34% of the mass of the epoxy resin emulsion, the corresponding flexural strength of the modified material is 13.98 MPa, and the flexural compressive ratio is 0.503. At this time, the corresponding sustainability potential index Ks S 2.047, which indicates that the ratio is improved compared with the original group when the economic cost, flexural strength, compressive strength and flexural compressive ratio of the repair material are considered comprehensively.

[0127] The above-mentioned sustainability potential index Ks S The extreme value of the formula (i.e. the objective function) is usually obtained by partial derivation, that is, according to the mathematical definition, the condition for the extreme value of the sustainability potential index Ks is that the partial derivative is 0, and the two equations are equal to 0 to obtain the optimal ratio based on the sustainability potential index considering the compressive strength, flexural strength and economy.

[0128] The optimal ratio based on the sustainability potential index of the present embodiment is (5.352, 0.309), that is, the starch phosphate content is 5.352% of the content of the super-fine cement, and the polyurea content is 0.309% of the mass of the epoxy resin emulsion. Therefore, the modified repair material of starch phosphate and polyurea can be comprehensively evaluated, considering the flexural and compressive strengths and the economic cost, which has reference significance.

[0129] Example 4: Microscopic mechanism analysis of silane modified repair material based on scanning electron microscope

[0130] The present application uses a scanning electron microscope (SEM) to take pictures of the sample morphology of the modified epoxy resin repair material. The C0 group in the orthogonal test group is selected for microscopic mechanism research. The 28d flexural strength of the C0 group is the best. The cement-sand ratio of the C0 group is 1:1.2, the water-cement ratio is 0.24, the cement replacement amount of kaolin is 30%, and the silane content is 0.25% of the mass of the epoxy resin. Figure 9The SEM images of C0 group (original group without starch phosphate and polyurea) at different magnifications. As can be seen from the figure, the structure is distributed with spherical and ellipsoidal particles, which is inferred from the composition and reaction characteristics of the material after the curing of the waterborne epoxy resin. These epoxy resin curing particles are dispersed between the sheet structure and other components, which effectively bond different components together by their own bonding properties, while their own elastic properties play a toughening role, improve the flexibility and impact resistance of the material, and improve the deformation ability and resistance to damage of the material when subjected to external force. From the SEM electron morphology image, it can be clearly seen that there is a linking structure between the epoxy resin and the ultra-fine cement, and the irregular agglomerates in the figure are the products of the action of silane coupling agent Kh550: one end of Kh550 is amino (-NH2), which can carry out condensation reaction with the hydroxyl group (-OH) on the surface of cement and kaolin to form a stable chemical bond; the other end of the organic group can react with the epoxy resin to play a bridging function. That is, the silane coupling agent Kh550 closely connects the organic and inorganic materials to form an agglomerated structure, strengthens the interfacial bonding force between the components of the material, and thus effectively improves the overall mechanical properties and durability of the material. In addition, it can be seen from Figure 9 the figure that the porous sheet structure should be the micro-morphology of kaolin. A large number of small pores are distributed on the surface of these sheet materials, which confirms that kaolin has a high specific surface area. The high specific surface area enables kaolin to adsorb a large amount of cement hydration products and epoxy resin, and the chemical reactions that occur during the adsorption process can enhance the internal bonding force of the material. When the material is subjected to external force, its porous structure can to some extent buffer the stress and improve the crack resistance of the material.

[0131] On the basis of C0, the influence of polyurea and starch phosphate on the modified material was studied, and D1 group and D2 group were selected for SEM electron scanning, and the results are shown in Figure 10 and Figure 11 .

[0132] It can be seen from the figure that in the micrograph, there is a honeycomb structure in the D1 group that is obviously different from that in the C0 group, which should be starch phosphate. The starch phosphate molecule contains both hydrophilic and hydrophobic groups. In the material system, the hydrophilic groups interact with water molecules, and the hydrophobic groups aggregate with each other to form a unique network structure. This structure can increase the water retention of the modified material on the one hand, which helps the hydration reaction to proceed fully; on the other hand, its network structure can limit the movement of particles in the material, play a certain thickening effect, and effectively improve the construction performance of the material. In addition, this network structure can also enhance the internal bonding force of the material, making the starch phosphate more closely combined with kaolin and cement, and improving the overall performance of the material. The long fibrous structure in the figure should be polyurea. Polyurea has good flexibility and high strength, and the fibrous structure formed can play a key role in reinforcing and toughening the material. These fibrous structures like "skeleton" when the material is subjected to tensile or impact load, the fibers can effectively bear stress, improve the tensile and impact resistance of the material, and effectively prevent crack propagation. At the same time, these fibrous structures are interspersed between other components, further enhancing the integrity of the material, so that the components of the material work together to resist external forces.

[0133] The number of irregular agglomerates in the D1 and D2 groups increases compared with the C0 group, but the amount of silane coupling agent Kh550 is not increased in the two groups, which shows that in addition to the effect of the silane coupling agent itself, starch phosphate and polyurea also participate in the formation of the agglomerate structure. This complex agglomerate structure has a positive significance for improving the performance of the material and optimizes the interfacial compatibility between the components of the material. When the material is subjected to external force, the stress is more evenly transmitted between the components, improving the comprehensive performance of the material.

[0134] The above describes only the preferred specific embodiments of the present application, and the protection scope of the present application is not limited thereto. Any simple change or equivalent replacement of the technical solutions within the scope of the disclosed technology can be obtained by those skilled in the art, which falls within the protection scope of the present application.

Claims

1. A high-toughness modified epoxy resin repair material based on quality-price ratio, characterized in that: The invention comprises the following components: ultrafine cement, kaolin, water, water-based epoxy resin, epoxy resin curing agent, silane coupling agent, defoaming agent, starch phosphate and polyurea, wherein the ultrafine cement and kaolin are mixed into dry material, the ring-cement ratio (water-based epoxy resin: dry material) is 1:1.2, the water-cement ratio is 0.24, the kaolin accounts for 30% of the dry material, the silane coupling agent accounts for 0.25% of the mass of the water-based epoxy resin, the mass ratio of the water-based epoxy resin to the epoxy resin curing agent is 1:1.5, the epoxy resin emulsion is a mixture of epoxy resin and epoxy resin curing agent, the defoaming agent accounts for 1% of the epoxy resin emulsion, and the starch phosphate accounts for 2.5%-10% of the ultrafine cement. %, and the polyurea content accounts for 0.25%-1% of the mass of the epoxy resin emulsion; the preparation method of the high-toughness modified epoxy resin repair material comprises the following steps: weighing ultrafine cement, kaolin, water, epoxy resin, epoxy resin curing agent, silane coupling agent, defoaming agent, starch phosphate and polyurea; slowly dry-mixing the ultrafine cement and kaolin for 2 minutes to uniformly mix to obtain a cement filler; pouring the epoxy resin and the epoxy resin curing agent into a beaker and slowly stirring to uniformly mix, then adding water and the defoaming agent and stirring for 2 minutes to obtain a mixture; pouring the mixture into the cement filler and stirring to uniformly mix, then adding the silane coupling agent and stirring until uniform and free of lumps, then adding the polyurea and continuing to stir at a uniform speed to uniformly obtain a modified cement slurry.

2. The high-toughness modified epoxy resin repair material based on quality-price ratio according to claim 1, characterized in that: The silane coupling agent is silane coupling agent Kh550.

3. The high-toughness modified epoxy resin repair material based on quality-price ratio according to claim 1, characterized in that: The defoaming agent is an organosilicon defoaming agent.

4. The high-toughness modified epoxy resin repair material based on quality-price ratio according to claim 1, characterized in that: The starch phosphate content is 2.5% of the ultrafine cement content.

5. The high-toughness modified epoxy resin repair material based on quality-price ratio according to claim 4, characterized in that: The polyurea content is 0.25% of the mass of the epoxy resin emulsion.

6. The optimization method of the high-toughness modified epoxy resin repair material based on quality-price ratio according to claim 1, characterized in that: The following steps are involved: Step 1: According to the different starch phosphate contents, multiple starch phosphate experimental groups and a starch phosphate-free reference group are set as a starch phosphate reference group, wherein the starch phosphate experimental groups all contain ultrafine cement, kaolin, water, water-based epoxy resin, epoxy resin curing agent, silane coupling agent, defoaming agent and polyurea, and the amounts of other components are the same between the experimental groups; according to the different polyurea contents, multiple polyurea experimental groups and a polyurea reference group without polyurea are set, wherein the polyurea experimental groups all contain ultrafine cement, kaolin, water, water-based epoxy resin, epoxy resin curing agent, silane coupling agent, defoaming agent and starch phosphate, and the amounts of other components except polyurea are the same between the experimental groups and the same as those in the starch phosphate experimental group; each experimental group and each reference group are prepared to obtain a repair material, which is cured for 3 days, 7 days and 28 days, and the flexural strength and compressive strength of the repair material at the corresponding age are tested; finally, a group of concrete containing neither starch phosphate nor polyurea is prepared according to the same content as the control group; Step 2: Fit the 28d flexural strength and compressive strength of the starch phosphate and polyurea test groups. The fitting formula for flexural strength is as follows: Wherein, x represents the starch phosphate content, in %, y represents the polyurea content, in %, and f kz is the flexural strength; R of the fitting surface corresponding to the flexural strength 2 =0.8721, the fitting degree is high, and the effect of starch phosphate and polyurea on the flexural strength of the modified material is accurately simulated; Calculate the partial derivatives of x and y in the fitting formula of flexural strength: To achieve the extreme value of flexural strength, the partial derivative must be 0, and the stationary point (3.87, 0.32) is obtained. The second-order partial derivative discriminant is used to determine whether the stationary point is an extreme point. The stationary point (3.87, 0.32) is the maximum point of this function, and the corresponding maximum flexural strength is 14.06 MPa; that is, when the starch phosphate content is 3.87% of the ultrafine cement content and the polyurea content is 0.32% of the epoxy resin emulsion mass, the modified material has the best flexural strength of 14.06 MPa, and the corresponding compressive strength is 27.425 MPa, with a flexural-compression ratio of 0.513, which is 241.7% higher than that of C30 concrete. Based on the flexural strength prediction equation established by the fitting method, the optimal ratio considering the flexural strength index can be obtained by the derivation method. The fitting formula for compressive strength is: Wherein, x represents the starch phosphate content, in %; y represents the polyurea content, in %. R of the fitting surface corresponding to the compressive strength 2 =0.9735, the fitting degree is very high, and the effects of starch phosphate and polyurea on the compressive strength of the modified material can be accurately simulated; Find the partial derivatives of x and y in the fitting formula for compressive strength: When the partial derivative is 0, the stationary point (2.83, 0.34) is obtained, and the second-order partial derivative discriminant is used to determine whether the stationary point is an extreme point. The stationary point (2.83, 0.34) is the maximum point of this function, and the corresponding maximum compressive strength is 27.81 MPa; that is, when the starch phosphate content is 2.83% of the ultrafine cement content and the polyurea content is 0.34% of the epoxy resin emulsion mass, the maximum compressive strength of the modified material is 27.81 MPa, and the corresponding flexural strength is 13.98 MPa; based on the compressive strength prediction equation established by the fitting method, the optimal ratio considering the compressive strength index can be obtained by the derivation method, that is, the optimized range of the starch phosphate content of the modified epoxy resin repair material to the ultrafine cement content is 2.83% to 3.87%, and the polyurea content is 0.32% to 0.34% of the epoxy resin emulsion mass, and the comprehensive performance is good; Step 3: Calculate the cost sustainability potential index K for the different groups set in step 1. S According to the test method of starch phosphate, the initial potential index value K of the modified material prepared by polyurea was calculated. S,0 and the sustainability potential index K considering the reduction / compression ratio S The calculation formulas are as follows: Among them, K S,0 is the initial potential index value, K S is the sustainability potential indicator considering the reduction / compression ratio, f kz and f ky represent flexural strength and compressive strength respectively, E represents the economic cost of concrete material, L represents the flexural-compression ratio of the material, the ref subscript represents the reference concrete, and no subscript represents the concrete under study; The larger the value of the sustainability potential index, the better the performance of the concrete material group, which is durable, sustainable and cost-effective, and can meet the requirements of different strength grades in different application scenarios; Based on the current market price a of the material, the cost is calculated using the following formula: E=a+0.035x+1.031y Wherein, a represents the current market price, x represents the percentage of starch phosphate added to the ultrafine cement content, and y represents the percentage of polyurea added to the epoxy resin emulsion content. Substituting the cost calculation formula into the sustainable potential index Ks, it can be seen that the consideration of the compression ratio of starch phosphate and polyurea modified repair materials is The original group without starch phosphate and polyurea has a 28-day flexural strength of 13.7 MPa and a 28-day compressive strength of 24.3 MPa. The flexural-compression ratio is 0.564, and the corresponding original sustainability potential index K S The value is 2; According to the maximum flexural strength obtained in step 2, it is 14.06MPa; that is, the starch phosphate content is 3.87% of the ultrafine cement content, the polyurea content is 0.32% of the epoxy resin emulsion mass, and the corresponding compressive strength of the modified material is 27.425MPa, with a flexural-compression ratio of 0.

513. The corresponding sustainability potential index K S It is 2.065, which means that this ratio is improved when the economic cost, flexural strength, compressive strength and flexural-compression ratio of the repair material are comprehensively considered; According to the maximum compressive strength obtained in step 2, it is 27.81 MPa; that is, when the starch phosphate content is 2.83% of the ultrafine cement content and the polyurea content is 0.34% of the epoxy resin emulsion mass, the corresponding flexural strength of the modified material is 13.98 MPa, and the flexural-compression ratio is 0.503; the corresponding sustainability potential index K S It is 2.047, which means that when the economic cost, flexural strength, compressive strength and flexural-compression ratio of the repair material are comprehensively considered, this combination is improved compared with the original group; Sustainable potential indicator K S To find the extreme value of the formula (i.e., the objective function), the partial derivative is usually calculated. That is, according to the mathematical definition, the condition for the sustainable potential index Ks to take the extreme value is that the partial derivative is 0. By setting the two equations equal to 0, the optimal ratio based on the sustainable potential index that takes into account the compressive strength, flexural strength and economy can be obtained.

7. Use of the high-toughness modified epoxy resin repair material with a high quality-price ratio according to claims 1 to 6 in repairing microcracks in tunnel linings.

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