A binary composite fiber-reinforced epoxy resin-based rapid repair material and its preparation method

Abstract

This invention relates to the field of repair materials technology, and discloses a binary composite fiber-reinforced epoxy resin-based rapid repair material and its preparation method, comprising the following raw materials in the indicated mass ratios: 259.85g epoxy resin, 89.36g curing agent, 25.99g diluent, 24.22g toughening agent, 1200g fine aggregate, 259.85g filler, 1.04g defoamer, 0.78-2.34g basalt fiber, and 15.59-31.18g calcium sulfate whiskers. In this invention, the large-scale basalt fiber and the small-scale calcium sulfate whiskers are mixed and incorporated into the binary composite fiber-reinforced epoxy resin-based rapid repair material and its preparation method. The abundant freely distributed fibers can constrain the propagation of microcracks of different sizes and regions within the repair material matrix, effectively improving the shortcomings of conventional epoxy resin-based repair materials, such as poor early performance, high brittleness, and insufficient toughness, achieving a balance between high early strength and high toughness in the epoxy resin-based repair material.

Description

Technical Field

[0001] This invention relates to the field of repair materials technology, specifically to a binary composite fiber-reinforced epoxy resin-based rapid repair material and its preparation method. Background Technology

[0002] With the continuous development of national infrastructure and large-scale industrial buildings, the demand for the construction, maintenance, renovation and reinforcement of concrete structures such as cross-sea bridges, underground tunnels and offshore platforms is constantly growing.

[0003] Rapid, mobile, flexible, and efficient support is the basic requirement for emergency repair and reinforcement, and the application of new technologies and materials is an important foundation for emergency engineering repair. In recent years, rapid repair materials have developed rapidly, with a series of repair materials such as sulfoaluminate cement and magnesium phosphate cement being developed both domestically and internationally. Their development is relatively mature, and they can achieve good application results in conventional construction during peacetime. However, these repair materials still have certain shortcomings in terms of hardening speed, construction technology, product energy consumption, and production cost, which limits their application in emergency repairs under complex conditions.

[0004] Considering the stringent time requirements of emergency repairs in engineering projects, and to rapidly and efficiently improve the repair capabilities of civilian and industrial facilities, it is necessary to develop an emergency repair material with a simple manufacturing process, fast curing speed, and high early strength. Epoxy resin-based repair materials are a novel organic-inorganic cementitious material. Epoxy resin and a curing agent form an epoxy resin-curing agent cementitious system, impregnating and encapsulating inorganic fillers such as sand and cement to form a high-strength solidified body. This type of repair material combines the setting speed of the organic epoxy resin with the filling effect of the inorganic materials, exhibiting advantages over cement-based repair materials in early strength, curing speed, formulation design flexibility, and interfacial adhesion. It is also important to note that as a high-performance repair material adapted to the needs of modern warfare, it not only needs to possess higher strength but also better toughness. Therefore, it is necessary to modify and optimize conventional repair materials. Basalt fiber (BF) is a novel, environmentally friendly reinforcing material. Compared to traditional fibers such as glass fiber, it exhibits superior mechanical strength and thermal stability, along with high tensile strength, resistance to acid and alkali corrosion, and stable chemical properties. Calcium sulfate whiskers (CSW) are fibrous single crystals, belonging to the sub-nanomaterial category. They possess good compatibility with epoxy resin matrices and, when used as a reinforcing phase, combine the reinforcing effects of both fibers and inorganic fillers, resulting in both strengthening and toughening effects, thus possessing significant application value. Therefore, using a hybrid of basalt fiber and calcium sulfate whiskers to reinforce epoxy resin-based repair materials can leverage the multi-scale synergistic strengthening and toughening effects of the two fiber materials at different size levels, demonstrating great potential for effectively improving the strength properties and deformability of materials. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a binary composite fiber-reinforced epoxy resin-based rapid repair material and its preparation method. By mixing and incorporating large-scale basalt fibers and small-scale calcium sulfate whiskers, the expansion and extension of cracks in different regions and at different scales within the repair material matrix can be constrained, effectively improving the defects of conventional epoxy resin-based repair materials, such as poor early performance, high brittleness, and insufficient toughness.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A binary composite fiber-reinforced epoxy resin-based rapid repair material comprises the following raw materials in the indicated mass ratios: 259.85g epoxy resin, 89.36g curing agent, 25.99g diluent, 24.22g toughening agent, 1200g fine aggregate, 259.85g filler, 1.04g defoamer, 0.78-2.34g basalt fiber, and 15.59-31.18g calcium sulfate whiskers.

[0010] Preferably, the basalt fiber has a mass ratio of 0.3% to epoxy resin and a mass of 0.78g; the calcium sulfate whiskers have a mass ratio of 9% to epoxy resin and a mass of 23.39g.

[0011] Preferably, the material further includes anhydrous ethanol and a silane coupling agent that have undergone surface modification treatment of basalt fibers and calcium sulfate whiskers.

[0012] Preferably, the fine aggregate is medium sand with a bulk density of 1470 kg / m³. 3 The apparent density is 2635 kg / m³. 3 The fineness modulus is 2.9, and the mass of particles with a diameter greater than 0.25 mm is greater than 50%.

[0013] Preferably, the filler is ordinary Portland cement with a strength grade of 42.5.

[0014] A method for preparing a binary composite fiber-reinforced epoxy resin-based rapid repair material includes the following steps:

[0015] S1: Before preparation, epoxy resin, curing agent, diluent and toughening agent are placed in a 40℃ water bath for 4 hours and preheated. Cement, sand and defoaming powder are placed in a 30℃ drying oven for 12 hours for later use.

[0016] S2: Surface modification treatment of basalt fibers and calcium sulfate whiskers to obtain modified basalt fibers and modified calcium sulfate whiskers for later use;

[0017] S3: Weigh sand, cement, epoxy resin, curing agent, diluent, toughening agent, and defoamer according to the mixing ratio. The weighing should be accurate to ±0.05g.

[0018] S4: First, pour the preheated epoxy resin, diluent, and toughening agent from the water bath into a beaker and stir for 60 seconds to obtain a mixture to reduce the viscosity of the epoxy resin. Then, pour the curing agent and defoamer into the beaker and stir with an electric stirrer for 60 seconds until the mixture is uniform to make an epoxy resin adhesive.

[0019] S5: Add the weighed cement and sand into the mixing pot and stir slowly for 30 seconds until they are evenly mixed to obtain mixture A; mix calcium sulfate whiskers and basalt fibers in advance to ensure stable dispersion, and then add the materials by slowly sprinkling the fibers in multiple batches while stirring, and continue stirring for 120 seconds until the fibers are evenly dispersed and no agglomeration or clustering occurs to obtain mixture B; then pour in the prepared epoxy resin solution, stir slowly for 30 seconds, and then stir quickly for 60 seconds to fully mix the solid and the epoxy resin solution;

[0020] S6: Fix the 40mm×40mm×160mm triple mold on the vibration table, put the mixture into the mold in two layers, and vibrate each layer 60 times. After vibration, smooth the surface of the specimen with a scraper. Place the specimen in a standard environmental curing chamber with a temperature of 20℃±2℃ and a relative humidity of (50±5)%. Demold after 1 hour, and then continue curing until the test age (4 hours).

[0021] Preferably, the basalt fiber surface modification treatment steps are as follows:

[0022] ① At an ambient temperature of 25℃, according to m 水 :m 无水乙醇 =1:20, weigh water and anhydrous ethanol, mix them thoroughly, and prepare an ethanol solution;

[0023] ②According to m 水 :m 硅烷偶联剂 =1:1, weigh out the silane coupling agent KH-550 solution, add it to the ethanol solution, and stir thoroughly again;

[0024] ③ Add the basalt fiber required for the experiment to the solution, stir and disperse the fiber with a glass rod, and then place the container in an 80℃ constant temperature water bath and heat for 1 hour;

[0025] ④ The processed basalt fibers are dried in a 100℃ drying oven to obtain modified basalt fibers.

[0026] Preferably, the surface modification treatment of the calcium sulfate whiskers involves the following steps:

[0027] ① At an ambient temperature of 25℃, according to m 水 :m 无水乙醇 =1:20, weigh water and anhydrous ethanol, mix them thoroughly, and prepare an ethanol solution;

[0028] ②According to m 水 :m 硅烷偶联剂 =1:1, weigh out the KH-550 solution, add it to the ethanol solution, and stir thoroughly again;

[0029] ③ Add the calcium sulfate whiskers required for the experiment to the solution, stir and disperse the fibers with a glass rod, and then place the container in an 80℃ constant temperature water bath and heat for 1 hour.

[0030] ④ The processed calcium sulfate whiskers are dried in a 100℃ drying oven to obtain modified calcium sulfate whiskers.

[0031] (III) Beneficial Effects

[0032] Compared with the prior art, the present invention provides a binary composite fiber-reinforced epoxy resin-based rapid repair material and its preparation method, which has the following beneficial effects:

[0033] 1. This invention improves the early performance of epoxy resin-based repair materials at multiple scales by adding graded fiber reinforcements and modifiers. In the basalt fiber-calcium sulfate whisker binary composite fiber-reinforced epoxy resin-based rapid repair material, large-scale basalt fibers and small-scale calcium sulfate whiskers are mixed and incorporated. The large number of freely distributed fibers can constrain the propagation of microcracks at different scales in different regions inside the repair material matrix, effectively improving the defects of conventional epoxy resin-based repair materials such as poor early performance, high brittleness, and insufficient toughness, and achieving a match between high strength and high toughness in the early performance of epoxy resin-based repair materials.

[0034] 2. The early compressive strength and flexural strength of the binary composite fiber reinforced epoxy resin-based rapid repair material of this invention are higher than those of rapid-hardening sulfoaluminate cement mortar, which can be applied in a wider range, has a stronger load-bearing capacity, and improves the mechanical properties of the repair material. From a process perspective, the binary composite fiber reinforced epoxy resin-based rapid repair material does not require water curing, which reduces the number of procedures and improves construction efficiency.

[0035] 3. In the fiber-modified epoxy resin-based rapid repair material prepared by this invention, basalt fibers and calcium sulfate whiskers improve the internal microstructure of the repair material, reduce internal porosity, and the basalt fibers act as bridges to inhibit the development of macroscopic cracks, while the calcium sulfate whiskers act as fillers to optimize internal micropores and improve the density of the repair material. The rational blending of two fibers of different sizes fully utilizes their performance-enhancing properties at different size levels to achieve a synergistic and complementary strengthening and toughening effect.

[0036] 4. The fiber-modified epoxy resin-based rapid repair material prepared by the present invention has excellent early flexural strength, compressive strength and toughness.

[0037] 5. The fiber-modified epoxy resin-based rapid repair material prepared by this invention is relatively cheaper than most other resin-based rapid repair materials on the market.

[0038] In summary, binary composite fiber reinforced epoxy resin-based rapid repair material is a new type of rapid repair material with excellent performance and high cost performance. Attached Figure Description

[0039] Figure 1 This is a diagram illustrating the preparation of the binary composite fiber-reinforced epoxy resin-based rapid repair material of the present invention.

[0040] Figure 2 Figure 1 shows the effect of basalt fiber-calcium sulfate whisker blending on the flowability of epoxy resin-based repair materials.

[0041] Figure 3 Figure 1 shows the effect of basalt fiber-calcium sulfate whisker blending on the flexural strength of epoxy resin-based repair materials.

[0042] Figure 4 The figure shows the effect of basalt fiber-calcium sulfate whisker mixture on the compressive strength of epoxy resin-based repair materials. Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0044] Example:

[0045] Please see Figure 1-4 A binary composite fiber-reinforced epoxy resin-based rapid repair material comprises the following raw materials: 259.85g epoxy resin, 89.36g curing agent, 25.99g diluent, 24.22g toughening agent, 1200g fine aggregate, 259.85g filler, 1.04g defoamer, 0.78-2.34g basalt fiber, and 15.59-31.18g calcium sulfate whiskers.

[0046] The material also includes anhydrous ethanol and silane coupling agents that have undergone surface modification treatment of basalt fibers and calcium sulfate whiskers.

[0047] Raw materials:

[0048] 1. Epoxy resin: WSR629 epoxy resin (E-51) was selected, and its main performance indicators are shown in Table 1.

[0049] Table 1 Main performance indicators of epoxy resin

[0050]

[0051]

[0052] 2. Curing agent: TE80-593 epoxy resin curing agent produced by Jiangyin Wanqian Chemical Co., Ltd. was selected. Its main performance indicators are shown in Table 2.

[0053] Table 2 Main performance indicators of curing agent

[0054] Inspection items Project Indicators Test results Appearance - Colorless to pale yellow transparent liquid Relative density (20℃) 0.96～1.05 0.985 Epoxy equivalent (g / mol) 183～195 190 Amine value (mg KOH / g) 500～600 550 Viscosity at 25℃ (mPa·s) 90～150 100

[0055] 3. Diluent: TC-AGE, an active diluent produced by Jiangyin Wanqian Chemical Co., Ltd., was selected. Its main performance indicators are shown in Table 3.

[0056] Table 3 Main performance indicators of diluent

[0057] Inspection items Project Indicators Test results Appearance - transparent liquid Color (APHA) ≤30 10 Epoxy content (equivalent / 100g) 0.30-0.35 0.33 Inorganic chlorine value (equivalents / 100g) ≤0.005 0.00037 Organochlorine value (equivalents / 100g) ≤0.02 0.00130 Viscosity at 25℃ (mPa·s) 5-10 8.4 Moisture content (%) ≤0.1 0.045

[0058] 4. Toughening agent: Epoxy resin active toughening agent V2246 is selected, and its main performance indicators are shown in Table 4.

[0059] Table 4 Main performance indicators of toughening agents

[0060]

[0061] 5. Fine aggregate: Medium sand produced by Xi'an Ya'an Sand and Gravel Plant, with a bulk density of 1470 kg / m³. 3 The apparent density is 2635 kg / m³. 3 The fineness modulus is 2.9, and the mass of particles larger than 0.25 mm is greater than 50%. The sand should be cleaned and dried before use.

[0062] 6. Filler: As an important component of epoxy resin-based repair materials, filler can improve the density of the repair material, enhance its mechanical properties, and reduce the amount of epoxy resin used, thus lowering costs. P·O 42.5 ordinary Portland cement is selected. Since cement acts as a filler and does not participate in the curing reaction of the epoxy resin-based repair material, its physical properties are the primary focus. Its main physical property indicators are shown in Table 5.

[0063] Table 5 Main Physical Properties of Cement

[0064]

[0065] 7. Defoamer: DE-0544 organosilicon defoamer, industrial grade, produced by Zhengzhou Tenganchi Biotechnology Co., Ltd., was selected. Its main performance indicators are shown in Table 6.

[0066] Table 6 Main performance indicators of defoamers

[0067] Inspection items standard Test results Appearance White powder or granular solid White powdery solid Moisture content ≤5 3.1 Active ingredient / % 30±1 30 Defoaming performance / s ≤30 15

[0068] 8. Basalt fiber: Short-cut basalt fiber produced by Taian Haoda New Material Co., Ltd. is selected. The fiber length is 6mm. Its main performance indicators are shown in Table 7.

[0069] Table 7 Main performance indicators of basalt fiber

[0070] Inspection items Project Indicators Test results Diameter (μm) 9-25 17 Fiber length (mm) - 6 Tensile strength (MPa) ≥1250 1865 Elongation at break (%) ≤3.1 3.06 Elastic modulus (GPa) ≥40 46 Monofilament breaking strength retention rate (%) ≥75 90 <![CDATA[Density (g / cm 3 )]]> - 2.64

[0071] 9. Calcium sulfate whiskers: Anhydrous calcium sulfate whiskers produced by Jinan Qingtian Chemical Technology Co., Ltd. were selected. Their main performance indicators are shown in Table 8.

[0072] Table 8 Main performance indicators of calcium sulfate whiskers

[0073] Inspection items Project Indicators Test results Average diameter (μm) 0.2～6 1～5 Average length (μm) 30～200 50～200 Tensile strength (GPa) - 20.5 Tensile modulus (GPa) - 178 <![CDATA[CaSO4 content (%)]]> ≥96 ≥98 <![CDATA[Relative density (g / cm 3 )]]> - 2.61

[0074] 10. Silane coupling agent: KH-550 silane coupling agent produced by Jinan Xingfeilong Chemical Co., Ltd. was selected. Its main performance indicators are shown in Table 9.

[0075] Table 9 Key Performance Indicators of KH-550

[0076]

[0077]

[0078] 11. Anhydrous ethanol: Anhydrous ethanol produced by Sinopharm Chemical Reagent Co., Ltd. is selected. It is of analytical grade.

[0079] Basic mix proportions:

[0080] The basic mix design of the rapid repair material is shown in Table 10.

[0081] Table 10 Basic Mix Proportions of Quick Repair Materials

[0082] Sand-to-rubber ratio Ring-to-solid ratio toughening agent dosage % Diluent dosage % Filler ratio Defoamer dosage % 4.618 2.908 9.321 10 1 0.4

[0083] Furthermore, the basalt fiber content is 0.3%, 0.6%, and 0.9%; the calcium sulfate whisker content is 6%, 9%, and 12%. The specific formulation of the binary composite fiber-reinforced epoxy resin-based rapid repair material is shown in Table 11, where the two different fiber sizes are mixed and added.

[0084] Table 11. Mixing Proportions of Binary Composite Fiber Reinforced Epoxy Resin-Based Rapid Repair Material

[0085]

[0086]

[0087] Note: C represents calcium sulfate whiskers, B represents basalt fiber, and the numbers after the letters indicate the corresponding fiber content (calculated according to the mass ratio of epoxy resin).

[0088] Preparation method: includes the following steps:

[0089] S1: Before preparation, put epoxy resin, curing agent, diluent and toughening agent into a 40℃ water bath for 4 hours, and put cement, sand and defoaming powder into a 30℃ drying oven for 12 hours for later use.

[0090] S2: Surface modification treatment of basalt fibers and calcium sulfate whiskers to obtain modified basalt fibers and modified calcium sulfate whiskers for later use;

[0091] The surface modification treatment steps for basalt fibers are as follows: ① At an ambient temperature of 25℃, according to m 水 :m 无水乙醇 =1:20, weigh water and anhydrous ethanol, mix them thoroughly, and prepare an ethanol solution; ②According to m 水 :m 硅烷偶联剂 =1:1, weigh out the silane coupling agent KH-550 solution and add it to the ethanol solution, then stir thoroughly again; ③ Add the basalt fiber required for the experiment to the solution, stir and disperse the fiber with a glass rod, and then place the container in an 80℃ constant temperature water bath for 1 h; ④ Place the treated basalt fiber in a 100℃ drying oven to dry, and obtain modified basalt fiber; At the same time, referring to the basalt fiber modification method, use silane coupling agent KH-550 to modify calcium sulfate whiskers, and the operation steps are the same as the basalt fiber modification steps.

[0092] Since the surface of the original fiber material is relatively smooth, it usually exhibits low adhesion ability when directly mixed with epoxy resin without treatment. By treating the fiber surface, the interfacial bonding ability between the fiber and the epoxy resin matrix can be improved.

[0093] S3: Weigh the sand, cement, epoxy resin, curing agent, diluent, toughening agent, and defoamer according to the mixing ratio. The weighing should be accurate to ±0.05g.

[0094] S4: First, pour the preheated epoxy resin, diluent, and toughening agent from the water bath into a beaker and stir for 60 seconds to obtain a mixture to reduce the viscosity of the epoxy resin. Then, pour the curing agent and defoamer into the beaker and stir with an electric stirrer for 60 seconds until the mixture is uniform to make an epoxy resin adhesive.

[0095] S5: Add the weighed cement and sand into the mixing pot and stir slowly for 30 seconds until they are evenly mixed to obtain mixture A; mix calcium sulfate whiskers and basalt fibers in advance to ensure stable dispersion, and then add the materials by slowly sprinkling the fibers in multiple batches while stirring, and continue stirring for 120 seconds until the fibers are evenly dispersed and no agglomeration or clustering occurs to obtain mixture B; then pour in the prepared epoxy resin solution, stir slowly for 30 seconds, and then stir quickly for 60 seconds to fully mix the solid and the epoxy resin solution;

[0096] S6: Fix the 40mm×40mm×160mm triple mold on the vibration table, put the mixture into the mold in two layers, and vibrate each layer 60 times. After vibration, smooth the surface of the specimen with a scraper. Place the specimen in a standard environmental curing chamber with a temperature of 20℃±2℃ and a relative humidity of (50±5)%. Demold after 1 hour, and then continue curing until the test age (4 hours).

[0097] Test method:

[0098] Flowability test: The test was conducted according to the "Method for Determination of Flowability of Cement Mortar" (GB / T2419-2005), using a cement mortar flowability tester (jump table). The specific steps are as follows:

[0099] ① First, fill the sample into two-thirds of the truncated cone mold, tamp it down 5 times with a knife, and then tamp it down 15 times with a tamping rod. Then fill the sample again to 20mm above the truncated cone mold, tamp it down 5 times with a knife, and then tamp it down 15 times with a tamping rod. Then scrape the mold flat.

[0100] ② Gently lift the test mold vertically, then start the jumping table and complete 25 jumps;

[0101] ③ After the jump is completed, use a vernier caliper to measure the extension diameter in two mutually perpendicular directions, and take the average of the two measurements for the flowability.

[0102] Strength testing: The test was conducted according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-2021). The main tests were on the compressive and flexural strength of the epoxy resin-based repair material. The tests were performed using an integrated mortar flexural and compressive strength testing machine. First, the flexural test was conducted. The specimen was placed on the support cylinder of the flexural testing machine, and the loading rate was set to 50 N / s. Three specimens from the same group were tested, and the average of the three sets of test data was taken. The six half-prisms that broke after the flexural test were then subjected to a compressive strength test, with a loading rate set to 2.4 kN / s. The average of the six sets of test data was taken.

[0103] Test results:

[0104] According to road emergency repair standards, damaged roads must be repaired within 4 hours. Considering the requirements for rapid curing, quick hardening, and early strength in emergency road repairs, the strength testing age for the binary composite fiber-reinforced epoxy resin-based rapid repair material was set at 4 hours. Specimens were prepared according to the designed mix proportions, and the flowability, 4-hour compressive strength, and flexural strength of the repair material were tested. The compressive-flexural ratio was calculated, and the results are shown in Table 12.

[0105] Table 12. Early Performance Test Results of Binary Composite Fiber Reinforced Epoxy Resin-Based Rapid Repair Material

[0106]

[0107]

[0108] Results analysis:

[0109] 1. The effect of basalt fiber-calcium sulfate whisker blending on the flowability of epoxy resin-based repair materials:

[0110] The effect of basalt fiber and calcium sulfate whisker blending on the flowability of epoxy resin-based repair materials, such as Figure 2 As shown in the figure, the flowability of the repair material decreases with increasing amounts of basalt fiber and calcium sulfate whiskers, consistent with the trend observed when either fiber is added alone. Furthermore, the effect of mixed fibers on flowability is greater than that of single-fiber addition. For example, the flowability of the experimental group containing 9% calcium sulfate whiskers and 0.3% basalt fiber was 147 mm, both lower than the 151 mm of the group containing only 9% calcium sulfate whiskers and the 164 mm of the group containing only 0.3% basalt fiber. This is because the basalt fiber exhibits a three-dimensional random distribution in the epoxy resin-based repair material, forming a mesh structure that restricts the flow of the slurry, thus reducing the flowability of the epoxy resin-based repair material. When calcium sulfate whiskers are incorporated, their surface adsorbs a certain amount of epoxy slurry, further reducing the flowability of the repair material. The simultaneous incorporation of both fibers has a synergistic effect, further reducing the flowability.

[0111] 2. Effect of basalt fiber-calcium sulfate whisker blending on the flexural strength of epoxy resin-based repair materials:

[0112] The effect of basalt fiber and calcium sulfate whiskers on the flexural strength of epoxy resin-based repair materials, such as Figure 3 As shown in Figure 3(a), when the basalt fiber content is fixed, the flexural strength of the epoxy resin-based repair material first increases and then decreases with the increase of calcium sulfate whisker content. The strength increase is most significant when the calcium sulfate whisker content is between 0% and 6%, with an increase of over 25% in all cases, showing a large range of variation. However, when the basalt fiber content is 0.9%, the flexural strength of the mixed fiber is consistently lower than that of the single whisker. Figure 3(b) It can be seen that when the calcium sulfate whisker content is fixed, the flexural strength of the epoxy resin-based repair material first increases and then decreases with the increase of basalt fiber content, and the increase in flexural strength is not significant. (Summary) Figure 3 As shown in (a) and (b), the highest flexural strength, reaching 18.8 MPa, was achieved when the calcium sulfate whisker content was 9% and the basalt fiber content was 0.3%, which is higher than the strength of the single-whisker and single-fiber groups. This indicates that appropriate mixing of basalt fiber and calcium sulfate whiskers can leverage multi-layered complementary advantages to significantly improve the flexural strength of the repair material. However, it is worth noting that excessive fiber mixing can have a negative hybridization effect. This is because when excessive fiber is added to epoxy resin-based repair materials, the number of weak areas between the matrix and fiber increases. When the negative effect of these weak areas outweighs the strengthening effect of the fiber, the flexural strength of the epoxy resin-based repair material will decrease. Therefore, it is necessary to reasonably control the mixing ratio of basalt fiber and calcium sulfate whiskers to achieve the maximum reinforcing effect.

[0113] 3. Effect of basalt fiber-calcium sulfate whisker blending on the compressive strength of epoxy resin-based repair materials:

[0114] The effect of basalt fiber and calcium sulfate whiskers on the compressive strength of epoxy resin-based repair materials, such as Figure 4 As shown. From Figure 4 (a) It can be seen that when the basalt fiber content is 0.3%, 0.6%, and 0.9%, the compressive strength of the epoxy resin-based repair material first increases and then decreases with the increase of calcium sulfate whisker content. When the basalt fiber content is 0.3% and the calcium sulfate whisker content is 9%, the strength reaches a peak of 54.6 MPa. When the basalt fiber content is 0.9%, the flexural strength is always lower than that of the group without basalt fiber, indicating that excessive basalt fiber content has a negative effect on strength. Figure 4 (b) It can be seen that when the calcium sulfate whisker content is 6%, 9%, and 12%, the compressive strength of the epoxy resin-based repair material also first increases and then decreases with the increase of basalt fiber content, but the change is not significant. In summary... Figure 4 As shown in (a) and (b), the amount of calcium sulfate whiskers has a more significant effect on the compressive strength of epoxy resin-based repair materials than that of basalt fibers. This is because the larger amount of calcium sulfate whiskers allows them to act as fillers, significantly enhancing the compressive strength. In contrast, the incorporation of basalt fibers can inhibit crack development and provide some reinforcement, but its effect on compressive strength is not as pronounced.

[0115] 4. Optimal blending of basalt fiber and calcium sulfate whiskers:

[0116] By testing the early performance of epoxy resin-based repair materials after blending basalt fiber and calcium sulfate whiskers, and analyzing flowability, 4-hour flexural strength, and 4-hour compressive strength, the optimal combination of calcium sulfate whisker and basalt fiber content was selected. From the perspective of mechanical property enhancement, when the calcium sulfate whisker content was 9% and the basalt fiber content was 0.3%, although the flowability was 147 mm, the 4-hour compressive strength and 4-hour flexural strength both reached their maximum values ​​of 18.8 MPa and 54.6 MPa, respectively, and the compression-to-flexural ratio was 2.904 < 3, exhibiting excellent toughness characteristics. This indicates that the blending of these two fiber materials significantly reduced the brittleness of the epoxy resin-based repair material, achieving a good reinforcing and toughening effect.

[0117] Techno-economic analysis:

[0118] A techno-economic analysis was conducted, considering factors such as raw material costs and the efficiency improvements of repair materials. Based on market research, the market prices of raw materials for fiber-modified epoxy resin-based rapid repair materials are shown in Table 13.

[0119] Table 13 Unit Price of Raw Materials

[0120] type Unit price (yuan / kg) type Unit price (yuan / kg) Epoxy Resin E-51 35 OPC 42.5 0.31 Epoxy curing agent 593 40 Defoamer DE0544 14 Diluent AGE 25 Basalt fiber 10 Toughening agent V2246 34 Calcium sulfate whiskers 36 / / fine aggregate 0.06

[0121] The cost of the fiber-modified epoxy resin-based rapid repair material per cubic meter was estimated, with the cost per ton. The cost of this material is approximately 8045 yuan per ton. According to research, commercially available materials with similar performance for rapid repair include MMA rapid repair polymer mortar produced by Fenyangtang (Shanghai) Industrial Co., Ltd., and early-strength epoxy resin repair mortar produced by Beijing Wanji Jianye Building Materials Co., Ltd. The price of MMA rapid repair polymer mortar is approximately 9800 yuan / ton, and the price of early-strength epoxy resin repair mortar is approximately 18800 yuan / ton. Compared with MMA mortar and commercially available epoxy resin repair mortars, the fiber-modified epoxy resin-based rapid repair material prepared in this invention has a certain price advantage.

[0122] Mechanism analysis:

[0123] As an important reinforcing phase in resin-based cementitious materials, fibers can effectively improve the mechanical properties and deformation capacity of resin-based repair materials. Adding fibers to epoxy resin-based repair materials and thoroughly mixing them allows the fibers, epoxy resin, and aggregates to solidify into a hardened material, thus achieving strength. Overall, the strength and toughness of epoxy resin-based repair materials are improved when basalt fibers and calcium sulfate whiskers are added individually, but the improvement effect is even better when the two types of fibers are mixed, indicating that the two different sizes of fibers can fully utilize their different scale-enhancing effects.

[0124] Basalt fibers, with their large size and low elastic modulus, primarily function as bridges and absorb energy during fiber pull-out in the matrix, hindering the development of macroscopic cracks. Furthermore, basalt fibers exhibit a three-dimensional random distribution in epoxy resin-based repair materials, forming a mesh structure. As the fiber content increases, the average spacing between fibers decreases, resulting in a denser mesh structure that further enhances the compactness of the repair material, thereby improving its strength.

[0125] Calcium sulfate whiskers, as micron-sized short fibers, possess high elastic modulus and low elongation. Within the matrix, they can dissipate crack tip energy, reducing stress concentration at the crack tip within the repair material. During the microcrack development stage, they act as a bridge at the crack tip, deflecting stress to the crack side surface, hindering tip stress, and limiting microcrack propagation. When the stress further increases and the calcium sulfate whiskers can no longer prevent further crack propagation, the whiskers will be pulled out. During this pull-out process, mechanical interlocking and interfacial adhesion forces exist between the whisker surface and the epoxy resin-based repair material matrix, consuming the energy required for crack propagation.

[0126] When the two types of fibers are blended, calcium sulfate whiskers, due to their tiny size, play an initial role in the microcrack initiation stage, connecting the cracks, consuming some energy, and effectively limiting the initial crack growth. As the cracks further develop, the calcium sulfate whiskers reach their bearing capacity limit and are pulled out of the matrix, rendering their whisker function ineffective. At this point, basalt fibers act as a bridge, transferring stress from the matrix to the fibers through the interface between the fibers and the repair material. This reduces stress at the crack, inhibits crack propagation, and improves mechanical properties.

Claims

1. A binary composite fiber-reinforced epoxy resin-based rapid repair material, characterized in that: The raw materials include the following proportions by weight: 259.85 g epoxy resin, 89.36 g curing agent, 25.99 g diluent, 24.22 g toughening agent, 1200 g fine aggregate, 259.85 g filler, 1.04 g defoamer, 0.78 g basalt fiber, and 23.39 g calcium sulfate whiskers; The basalt fiber has a mass ratio of 0.3% to epoxy resin, and the calcium sulfate whiskers have a mass ratio of 9% to epoxy resin.

2. The binary composite fiber-reinforced epoxy resin-based rapid repair material according to claim 1, characterized in that: The material also includes anhydrous ethanol and silane coupling agents that have undergone surface modification treatment of basalt fibers and calcium sulfate whiskers.

3. The binary composite fiber-reinforced epoxy resin-based rapid repair material according to claim 1, characterized in that: The fine aggregate is medium sand with a bulk density of 1470 kg / m³. 3 The apparent density is 2635 kg / m³. 3 The fineness modulus is 2.9, and the mass of particles with a diameter greater than 0.25 mm is greater than 50%.

4. The binary composite fiber-reinforced epoxy resin-based rapid repair material according to claim 1, characterized in that: The filler is ordinary Portland cement with a strength grade of 42.

5.

5. A method for preparing a binary composite fiber-reinforced epoxy resin-based rapid repair material according to any one of claims 1-4, characterized in that: Includes the following steps: S1: Before preparation, epoxy resin, curing agent, diluent and toughening agent are placed in a 40 ℃ water bath for 4 h and preheated. Cement, sand and defoaming powder are placed in a 30 ℃ drying oven for 12 h and dried for later use. S2: Surface modification treatment of basalt fibers and calcium sulfate whiskers to obtain modified basalt fibers and modified calcium sulfate whiskers for later use; S3: Weigh sand, cement, epoxy resin, curing agent, diluent, toughening agent, and defoamer according to the mixing ratio. The weighing should be accurate to ±0.05 g. S4: First, pour the preheated epoxy resin, diluent, and toughening agent from the water bath into a beaker and stir for 60 seconds to obtain a mixture to reduce the viscosity of the epoxy resin. Then, pour the curing agent and defoamer into the beaker and stir with an electric stirrer for 60 seconds until the mixture is uniform to make an epoxy resin adhesive. S5: Add the weighed cement and sand to the mixing pot, stir slowly for 30 seconds until evenly mixed, and obtain the mixture. A Calcium sulfate whiskers and basalt fibers are mixed beforehand to ensure stable dispersion. Then, the fibers are slowly added in multiple batches while stirring, and stirring is continued for 120 seconds until the fibers are evenly dispersed without agglomeration or clustering, thus obtaining the mixture. B Then pour in the prepared epoxy resin solution, stir slowly for 30 seconds, and then stir rapidly for 60 seconds to fully mix the solid with the epoxy resin solution. S6: Fix a 40 mm × 40 mm × 160 mm triple mold on a vibration table. Fill the mold with the mixture in two layers and vibrate each layer 60 times. After vibration, smooth the surface of the specimen with a scraper. Place the specimen in a standard environmental curing chamber with a temperature of 20 ℃ ± 2 ℃ and a relative humidity of (50 ± 5)%. Demold after 1 h and continue curing until the test age (4 h).

6. The preparation method of a binary composite fiber-reinforced epoxy resin-based rapid repair material according to claim 5, characterized in that: The surface modification treatment steps for the basalt fiber are as follows: ①At an ambient temperature of 25 ℃, according to m 水 : m 无水乙醇 =1:20, weigh water and anhydrous ethanol, mix them thoroughly, and prepare an ethanol solution; ②According to m 水 : m 硅烷偶联剂 =1:1, weigh out the silane coupling agent KH-550 solution, add it to the ethanol solution, and stir thoroughly again; ③ Add the basalt fiber required for the experiment to the solution, stir and disperse the fiber with a glass rod, and then place the container in an 80 ℃ constant temperature water bath and heat for 1 h; ④ The processed basalt fibers are dried in a 100 ℃ drying oven to obtain modified basalt fibers.

7. The preparation method of a binary composite fiber-reinforced epoxy resin-based rapid repair material according to claim 5, characterized in that: The steps for surface modification treatment of calcium sulfate whiskers are as follows: ①At an ambient temperature of 25 ℃, according to m 水 : m 无水乙醇 =1:20, weigh water and anhydrous ethanol, mix them thoroughly, and prepare an ethanol solution; ②According to m 水 : m 硅烷偶联剂 =1:1, weigh out the KH-550 solution, add it to the ethanol solution, and stir thoroughly again; ③ Add the calcium sulfate whiskers required for the experiment to the solution, stir and disperse the fibers with a glass rod, and then place the container in an 80 ℃ constant temperature water bath and heat for 1 h; ④ The processed calcium sulfate whiskers are dried in a 100 ℃ drying oven to obtain modified calcium sulfate whiskers.

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