Geopolymer self-repairing microcapsule, preparation method and application thereof

Abstract

The present application belongs to the technical field of concrete crack repairing material, and particularly relates to a geopolymer self-repairing microcapsule, and also relates to a preparation method and application of the geopolymer self-repairing microcapsule. The raw materials for the geopolymer self-repairing microcapsule include acrylic acid, sodium hydroxide, zeolite, an initiator, a crosslinking agent, a capsule wall material, an emulsifier, an organic solvent and a dispersing agent. When cracks exist, the superabsorbent resin releases water, so that the cracks in the geopolymer continue to hydrate, and the cracks are repaired. This repairing method makes the interface combination more compact, and the interface is not prone to cracking when bearing load again.

Description

Technical Field

[0001] This invention belongs to the technical field of concrete crack repair materials, specifically relating to a geopolymer self-healing microcapsule, as well as the preparation method and application of the geopolymer self-healing microcapsule. Background Technology

[0002] Geopolymers possess characteristics such as rapid setting and early strength, good thermal stability, and strong interfacial bonding. They are also widely available, have low carbon emissions during preparation, and are more environmentally friendly, making them a preferred alternative to ordinary concrete. However, geopolymers are subject to many limitations in practical applications due to their high brittleness and susceptibility to cracking. Although polymer-modified geopolymers can effectively inhibit crack development, cracks generated in geopolymers under long-term loads still drastically shorten their service life.

[0003] Therefore, early self-healing of microcracks is crucial for improving the engineering performance of geopolymer materials. Current microencapsulation self-healing technologies, both domestically and internationally, mostly employ encapsulation of the repair fluid and dissolving the curing agent in the mixing water before adding it to the geopolymer. However, the curing agent gradually deteriorates over time, and the microcapsules are prone to breakage during geopolymer mixing, severely impacting the self-healing effect. Furthermore, most existing crack repair methods involve cross-linking and curing the repair agent and curing agent to fill the crack. This method creates an interface between the polymer and the geopolymer matrix, where the interface bond is weak, making it prone to cracking under renewed loads. Additionally, the curing agent incorporated into the geopolymer matrix is ​​often toxic, posing health risks and environmental pollution with prolonged exposure. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a geopolymer self-healing microcapsule, and also to provide a method for preparing the geopolymer self-healing microcapsule and its application.

[0005] The technical solution adopted in this invention is as follows:

[0006] A geopolymer self-healing capsule, by weight, contains the following raw materials: 10-20 parts acrylic acid, 4-8 parts sodium hydroxide, 5-10 parts zeolite, 0.03-0.2 parts initiator, 0.01-0.1 parts crosslinking agent, 30-60 parts capsule wall material, 10-20 parts emulsifier, 100-200 parts organic solvent, 150-250 parts dispersant, and 20-50 parts deionized water.

[0007] The size of the geopolymer self-healing microcapsules is 200-300 μm.

[0008] The initiator is potassium persulfate and / or sodium persulfate.

[0009] The crosslinking agent is N,N'-methylenebisacrylamide or divinylbenzene.

[0010] The emulsifier is one or more of Tween 20, Tween 40, Tween 80, and Span 80.

[0011] The organic solvent is one or more of anhydrous ethanol, dichloromethane, chloroform, and toluene; the dispersant is soybean oil or methyl silicone oil.

[0012] The capsule wall material is ethyl cellulose.

[0013] The method for developing geopolymer self-healing capsules includes the following steps:

[0014] (1) Weigh each raw material according to the proportion;

[0015] (2) Add sodium hydroxide to deionized water and stir for 1-3 minutes to prepare an alkaline solution;

[0016] (3) Add the alkaline solution to the acrylic acid under ice-water bath conditions and stir for 2-8 minutes. Then add the crosslinking agent and stir for 5-10 minutes. Finally, add the zeolite and stir to obtain a solution for 1-3 minutes.

[0017] (4) Disperse the solution obtained in step (3) with ultrasound for 5-10 min, then add the initiator and stir for 2-8 min, and then place it in a constant temperature water bath at 60-80℃ for 1-3 h to react;

[0018] (5) Dry the finished product from step (4), then grind it in a mortar for 10-20 minutes and then sieve it to obtain a zeolite-superabsorbent resin core with a particle size of 100-200μm.

[0019] (6) Add the capsule wall material and emulsifier to the organic solvent and stir for 5-10 minutes;

[0020] (7) Add the capsule core obtained in step (5) to the mixture prepared in step (6) and stir for 5-10 minutes;

[0021] (8) Add the emulsifier to the dispersant and stir for 5-10 minutes;

[0022] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir for 2-3 hours until the organic solvent is completely evaporated. Then filter, dry, and finally collect the geopolymer self-healing microcapsules.

[0023] In steps (3), (4), (6), (7), and (8), a magnetic stirrer is used for stirring at a speed of 200-600 r / min.

[0024] In step (9), the heating and stirring method is constant temperature heating stirrer, the stirring temperature is 60-80℃, and the stirring speed is 400-800r / min.

[0025] In step (5), the drying process is carried out at 50-80℃ for 24-36 hours.

[0026] In step (9), the drying process involves drying at 50-70℃ for 12-18 hours.

[0027] Application of the described geopolymer self-healing capsules in repairing concrete cracks.

[0028] Compared with the prior art, the beneficial technical effects of the present invention are:

[0029] 1. In this invention, acrylic acid, sodium hydroxide, initiator, and crosslinking agent in the core are chemically synthesized into superabsorbent polymer (SAP) within the porous zeolite pores. Under the action of the initiator and crosslinking agent, the acrylic acid monomer undergoes a polymerization reaction: n(CH2=CHCOOH)→[-CH2-CHCOO-] n Zeolite acts as the skeleton of SAP, increasing the strength of the capsule core and preventing the microcapsules from breaking during stirring, thus greatly improving the repair efficiency of the microcapsules.

[0030] 2. In this invention, the geopolymer repair capsule will not fail over time during use. When the geopolymer repair capsule is subjected to load and microcracks develop, the microcapsule breaks, releasing the pre-stored moisture inside the SAP into the microcracks, causing further hydration to repair the cracks. Furthermore, when the environment is humid, the SAP in the cracks absorbs water, expands rapidly, fills the cracks, and releases more water into the cracks to promote further hydration of the geopolymer.

[0031] 3. The core skeleton of the present invention is zeolite, and the pores are filled with superabsorbent resin. When cracks exist, the superabsorbent resin will release water, causing the cracks in the geopolymer to continue to hydrate and repair the cracks. This repair method makes the interface bond tighter and the interface is less likely to crack when subjected to load again.

[0032] 4. This invention utilizes the water-absorbing and waterproofing properties of highly absorbent resin to further hydrate and expand the cracks, eliminating the need for toxic curing agents and preventing environmental pollution. This method is safer and more environmentally friendly. Attached Figure Description

[0033] Figure 1 Images of the self-healing microcapsules from Example 1 are shown.

[0034] Figure 2 Images of self-healing microcapsules from Example 2 are shown.

[0035] Figure 3 Images of the self-healing microcapsules from Example 3 are shown.

[0036] Figure 4 Images of the self-healing microcapsules from Example 4 are shown.

[0037] Figure 5 Images of the self-healing microcapsules from Example 5 are shown.

[0038] Figure 6 Images of the self-healing microcapsules from Example 6 are shown.

[0039] Figure 7 Images of the self-healing microcapsules from Example 7 are shown.

[0040] Figure 8 Image of the self-healing microcapsule from Example 8.

[0041] Figure 9 Image of the self-healing microcapsule from Example 9. Detailed Implementation

[0042] The following examples illustrate specific implementations of the present invention. However, these examples are merely for illustrative purposes and do not limit the scope of the invention in any way.

[0043] In the following examples, acrylic acid (AA) is a colorless liquid with analytical purity; sodium hydroxide is a white crystalline powder with analytical purity; zeolite is commercially available natural zeolite with a particle size of 50 μm and a water content of 8%; in steps (2), (3), (4), (6), (7), and (8), a magnetic stirrer is used for stirring at a speed of 300 r / min.

[0044] Example 1:

[0045] A geopolymer self-healing microcapsule, the raw materials used are: 100g acrylic acid (AA), 40g sodium hydroxide, 50g zeolite, 0.3g potassium persulfate, 0.1g N,N'-methylenebisacrylamide, 300g ethyl cellulose, 100g Tween 20, 1000g anhydrous ethanol, 1500g soybean oil, and 200g deionized water.

[0046] Microcapsules were prepared using the following method:

[0047] (1) Weigh each raw material according to the required quantity;

[0048] (2) Add sodium hydroxide to deionized water and stir for 2 minutes to prepare an alkaline solution;

[0049] (3) Add sodium hydroxide solution to acrylic acid under ice-water bath conditions and stir for 2 min. Then add N,N'-methylenebisacrylamide and stir for 5 min. Finally add zeolite and stir for 1 min.

[0050] (4) Disperse the solution obtained in step (3) with ultrasound for 5 min, then add potassium persulfate and stir for 2 min, and then place it in a 60℃ constant temperature water bath for 1 h to react.

[0051] (5) The finished product was dried in a 50℃ drying oven for 24 hours, then ground in a mortar for 10 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 100μm.

[0052] (6) Add ethyl cellulose and Tween 20 to anhydrous ethanol and stir for 5 min;

[0053] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 5 min;

[0054] (8) Add the emulsifier to the soybean oil and stir for 5 minutes;

[0055] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (70°C, 600r / min) for 2 hours until the anhydrous ethanol is completely evaporated. Then filter, wash three times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0056] Example 2

[0057] A geopolymer self-healing microcapsule, the raw materials used are: 120g acrylic acid (AA), 50g sodium hydroxide, 60g zeolite, 0.5g sodium persulfate, 0.3g divinylbenzene, 400g ethyl cellulose, 110g Tween 40, 1200g dichloromethane, 1700g methyl silicone oil, and 300g deionized water.

[0058] Microcapsules were prepared using the following method:

[0059] (1) Weigh each raw material according to the required quantity;

[0060] (2) Add sodium hydroxide to deionized water and stir for 2 minutes to prepare an alkaline solution;

[0061] (3) Add sodium hydroxide solution to acrylic acid under ice-water bath conditions and stir for 3 minutes. Then add divinylbenzene and stir for 6 minutes. Finally, add zeolite and stir for 2 minutes.

[0062] (4) Disperse the solution obtained in step (3) by ultrasonication for 6 min, then add sodium persulfate and stir for 3 min, and then place it in a 70℃ constant temperature water bath for 2 h to react.

[0063] (5) The finished product was dried in a 60℃ drying oven for 26 hours, then ground in a mortar for 15 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 150μm.

[0064] (6) Add ethyl cellulose and Tween 40 to dichloromethane and stir for 6 minutes;

[0065] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 6 minutes;

[0066] (8) Add the emulsifier to the methyl silicone oil and stir for 6 minutes;

[0067] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (70°C, 400r / min) for 2 hours until the dichloromethane is completely evaporated. Then filter, wash 4 times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0068] Example 3

[0069] A geopolymer self-healing microcapsule, the raw materials used are: 150g acrylic acid (AA), 60g sodium hydroxide, 70g zeolite, 1g potassium persulfate, 0.5g N,N'-methylenebisacrylamide, 500g ethyl cellulose, 180g Tween 80, 1500g chloroform, 2000g soybean oil, and 400g deionized water.

[0070] Microcapsules were prepared using the following method:

[0071] (1) Weigh each raw material according to the required quantity;

[0072] (2) Add sodium hydroxide to deionized water and stir for 2 minutes to prepare an alkaline solution;

[0073] (3) Add sodium hydroxide solution to acrylic acid under ice-water bath conditions and stir for 7 min. Then add N,N'-methylenebisacrylamide and stir for 8 min. Finally add zeolite and stir for 2 min.

[0074] (4) Disperse the solution obtained in step (3) by ultrasonication for 8 minutes, then add potassium persulfate and stir for 6 minutes, and then place it in a 70°C constant temperature water bath for 2 hours to react.

[0075] (5) The finished product was dried in a 70℃ drying oven for 30 hours, then ground in a mortar for 16 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 200μm.

[0076] (6) Add ethyl cellulose and Tween 80 to chloroform and stir for 8 minutes;

[0077] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 8 minutes;

[0078] (8) Add the emulsifier to the soybean oil and stir for 8 minutes;

[0079] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (70°C, 800 r / min) for 3 h until the chloroform is completely evaporated. Then filter, wash 5 times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0080] Example 4

[0081] A geopolymer self-healing microcapsule, the raw materials used are: 200g acrylic acid (AA), 80g sodium hydroxide, 100g zeolite, 2g potassium persulfate, 1g divinylbenzene, 600g ethyl cellulose, 20g Span 80, 2000g toluene, 2500g methyl silicone oil, and 500g deionized water.

[0082] Microcapsules were prepared using the following method:

[0083] (1) Weigh each raw material according to the proportion;

[0084] (2) Add sodium hydroxide to deionized water and stir for 3 minutes to prepare an alkaline solution;

[0085] (3) Add sodium hydroxide alkaline solution to acrylic acid under ice-water bath conditions and stir for 8 minutes. Then add divinylbenzene and stir for 10 minutes. Finally, add zeolite and stir for 3 minutes.

[0086] (4) Disperse the solution obtained in step (3) by ultrasonication for 10 min, then add potassium persulfate and stir for 8 min, and then place it in an 80℃ constant temperature water bath for 3 h to react.

[0087] (5) The finished product was dried in an 80℃ drying oven for 36 hours, then ground in a mortar for 20 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 200μm.

[0088] (6) Add ethyl cellulose and Span 80 to an organic solvent and stir for 10 min;

[0089] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 10 min;

[0090] (8) Add the emulsifier to the methyl silicone oil and stir for 10 minutes;

[0091] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (70°C, 600r / min) for 3 hours until the toluene is completely evaporated. Then filter, wash 5 times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0092] Example 5

[0093] A geopolymer self-healing microcapsule, the raw materials used are: 110g acrylic acid (AA), 40g sodium hydroxide, 60g zeolite, 0.6g sodium persulfate, 0.3g divinylbenzene, 400g ethyl cellulose, 110g Tween 40, 1200g dichloromethane, 1600g methyl silicone oil, and 300g deionized water.

[0094] Microcapsules were prepared using the following method:

[0095] (1) Weigh each raw material according to the required quantity;

[0096] (2) Add sodium hydroxide to deionized water and stir for 2 minutes to prepare an alkaline solution;

[0097] (3) Add sodium hydroxide solution to acrylic acid under ice-water bath conditions and stir for 3 minutes. Then add divinylbenzene and stir for 6 minutes. Finally, add zeolite and stir for 2 minutes.

[0098] (4) Disperse the solution obtained in step (3) by ultrasonication for 6 min, then add sodium persulfate and stir for 3 min, and then place it in a 70℃ constant temperature water bath for 2 h to react.

[0099] (5) The finished product was dried in a 60℃ drying oven for 26 hours, then ground in a mortar for 15 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 150μm.

[0100] (6) Add ethyl cellulose and Tween 40 to dichloromethane and stir for 5 minutes;

[0101] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 5 min;

[0102] (8) Add Span 80 to methyl silicone oil and stir for 5 minutes;

[0103] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (60°C, 600r / min) for 2 hours until the dichloromethane is completely evaporated. Then filter, wash 4 times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0104] Example 6

[0105] A geopolymer self-healing microcapsule, the raw materials used are: 220g acrylic acid (AA), 90g sodium hydroxide, 120g zeolite, 3g potassium persulfate, 2g divinylbenzene, 600g ethyl cellulose, 20g Span 80, 2000g toluene, 2500g methyl silicone oil, and 500g deionized water.

[0106] Microcapsules were prepared using the following method:

[0107] (1) Weigh each raw material according to the proportion;

[0108] (2) Add sodium hydroxide to deionized water and stir for 3 minutes to prepare an alkaline solution;

[0109] (3) Add sodium hydroxide alkaline solution to acrylic acid under ice-water bath conditions and stir for 8 minutes. Then add divinylbenzene and stir for 10 minutes. Finally, add zeolite and stir for 3 minutes.

[0110] (4) Disperse the solution obtained in step (3) by ultrasonication for 10 min, then add potassium persulfate and stir for 8 min, and then place it in an 80℃ constant temperature water bath for 3 h to react.

[0111] (5) The finished product was dried in an 80℃ drying oven for 36 hours, then ground in a mortar for 20 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 200μm.

[0112] (6) Add ethyl cellulose and Span 80 to an organic solvent and stir for 10 min;

[0113] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 10 min;

[0114] (8) Add Tween 40 to methyl silicone oil and stir for 10 minutes;

[0115] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (80°C, 400r / min) for 3 hours until the toluene is completely evaporated. Then filter, wash 5 times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0116] Example 7

[0117] A geopolymer self-healing microcapsule, the raw materials used are: 110g acrylic acid (AA), 40g sodium hydroxide, 60g zeolite, 0.5g potassium persulfate, 0.3g N,N'-methylenebisacrylamide, 400g ethyl cellulose, 150g Tween 20, 1000g anhydrous ethanol, 1500g soybean oil, and 300g deionized water.

[0118] Microcapsules were prepared using the following method:

[0119] (1) Weigh each raw material according to the required quantity;

[0120] (2) Add sodium hydroxide to deionized water and stir for 2 minutes to prepare an alkaline solution;

[0121] (3) Add sodium hydroxide solution to acrylic acid under ice-water bath conditions and stir for 2 min. Then add N,N'-methylenebisacrylamide and stir for 5 min. Finally add zeolite and stir for 1 min.

[0122] (4) Disperse the solution obtained in step (3) with ultrasound for 5 min, then add potassium persulfate and stir for 2 min, and then place it in a 60℃ constant temperature water bath for 1 h to react.

[0123] (5) The finished product was dried in a 50℃ drying oven for 24 hours, then ground in a mortar for 10 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 100μm.

[0124] (6) Add ethyl cellulose and Tween 20 to anhydrous ethanol and stir for 7 min;

[0125] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 7 min;

[0126] (8) Add Span 80 to soybean oil and stir for 7 minutes;

[0127] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (70°C, 700r / min) for 2 hours until the anhydrous ethanol is completely evaporated. Then filter, wash three times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0128] Example 8

[0129] A geopolymer self-healing microcapsule, the raw materials used are: 170g acrylic acid (AA), 50g sodium hydroxide, 70g zeolite, 0.6g potassium persulfate, 0.5g N,N'-methylenebisacrylamide, 500g ethyl cellulose, 180g Tween 80, 1700g chloroform, 1800g soybean oil, and 400g deionized water.

[0130] Microcapsules were prepared using the following method:

[0131] (1) Weigh each raw material according to the required quantity;

[0132] (2) Add sodium hydroxide to deionized water and stir for 2 minutes to prepare an alkaline solution;

[0133] (3) Add sodium hydroxide solution to acrylic acid under ice-water bath conditions and stir for 7 min. Then add N,N'-methylenebisacrylamide and stir for 8 min. Finally add zeolite and stir for 2 min.

[0134] (4) Disperse the solution obtained in step (3) by ultrasonication for 8 minutes, then add potassium persulfate and stir for 6 minutes, and then place it in a 70°C constant temperature water bath for 2 hours to react.

[0135] (5) The finished product was dried in a 70℃ drying oven for 30 hours, then ground in a mortar for 16 minutes and sieved to obtain a zeolite-superabsorbent resin core with a particle size of 200μm.

[0136] (6) Add ethyl cellulose and Tween 80 to chloroform and stir for 8 minutes;

[0137] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 8 minutes;

[0138] (8) Add Tween 20 to soybean oil and stir for 8 minutes;

[0139] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (70°C, 500r / min) for 3 hours until the chloroform is completely evaporated. Then filter, wash 5 times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0140] Example 9

[0141] A geopolymer self-healing microcapsule, the raw materials used are: 120g acrylic acid (AA), 50g sodium hydroxide, 0.5g sodium persulfate, 0.3g divinylbenzene, 400g ethyl cellulose, 110g Tween 40, 1200g dichloromethane, 1700g methyl silicone oil, and 300g deionized water.

[0142] Microcapsules were prepared using the following method:

[0143] (1) Weigh each raw material according to the required quantity;

[0144] (2) Add sodium hydroxide to deionized water and stir for 2 minutes to prepare an alkaline solution;

[0145] (3) Add sodium hydroxide solution to acrylic acid under ice-water bath conditions and stir for 3 minutes. Then add divinylbenzene and stir for 6 minutes.

[0146] (4) Disperse the solution obtained in step (3) by ultrasonication for 6 min, then add sodium persulfate and stir for 3 min, and then place it in a 70℃ constant temperature water bath for 2 h to react.

[0147] (5) The finished product was dried in a 60℃ drying oven for 26 hours, then ground in a mortar for 15 minutes and sieved to obtain a highly absorbent resin core with a particle size of 150μm.

[0148] (6) Add ethyl cellulose and Tween 40 to dichloromethane and stir for 6 minutes;

[0149] (7) Add the sample obtained in step (5) to the mixture prepared in step (6) and stir for 6 minutes;

[0150] (8) Add the emulsifier to the methyl silicone oil and stir for 6 minutes;

[0151] (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir (70°C, 800r / min) for 2 hours until the dichloromethane is completely evaporated. Then filter, wash 4 times with anhydrous ethanol, dry, and finally collect the geopolymer self-healing microcapsules.

[0152] The geopolymer self-healing microcapsules prepared in Examples 1-9 were added to the geopolymer at 5% of the mass of the cementitious material. The geopolymer formulation consisted of 500g fly ash, 500g slag, 120g alkali activator, and 350g water. The alkali activator was a mixture of water glass and sodium hydroxide, with a modulus of 1.4 and a Na₂O content of 7%. A blank geopolymer was used as a control group.

[0153] The compressive strength was tested according to GB / T 17671—2021 "Test Method for Strength of Cement Mortar (ISO Method)". The tests were as follows: (1) The test block was cured in a standard curing room for 7 days and the compressive strength was tested. (2) The test block was cured in a standard curing room for 28 days and the compressive strength was tested. (3) The test block was cured in a standard curing room for 7 days, and after pre-pressing the crack with 75% of the 7-day strength, it was cured for another 21 days and the compressive strength was tested. The specific test data are shown in the table below. The above self-healing polymer material specimen was placed on a press and pressurized at a pressurization rate of 0.2 MPa / s. When the maximum bearing pressure was reached and cracks appeared, the pressurization was stopped. The permeability was tested at 3 days, 7 days and 28 days of curing using a core displacement flow device (test conditions: displacement pressure: 0.5 MPa, confining pressure: 2.5 MPa). The permeability test results are listed in Table 2.

[0154] Table 1 Compressive strength of pre-stressed cracks in Examples 1-9 and Control Examples at 7d and 28d.

[0155]

[0156] Table 2. Permeability of Examples 1-8 and Control Examples at 3d, 7d, and 28d

[0157] Application Example 1 40 7 <1 Application Example 2 32 8 <1 Application Example 3 26 4 <1 Application Example 4 33 8 <1 Application Example 5 29 5 <1 Application Example 6 33 7 <1 Application Example 7 24 6 <1 Application Example 8 40 9 <1 Application Example 9 58 28 10 Comparison Example 61 32 19

[0158] The results in the table above show that adding the self-healing capsules of this invention to the geopolymer had no adverse effect on the 7-day and 28-day compressive strength of the test blocks, and was comparable to that of the control example blank geopolymer. Furthermore, the compressive strength of the test block with added self-healing capsules after pre-compression cracking was greater than that of the test block without microcapsules, indicating that the self-healing microcapsules of the geopolymer have a significant repair effect on cracks.

[0159] Without the addition of zeolite (Application Example 9), most of the microcapsules broke during the geopolymer mixing and molding process. The broken microcapsules absorbed water and swelled, leading to failure and a decrease in the geopolymer's performance. After molding, the geopolymer's pre-stressed crack compressive strength and permeability at various ages were comparable to the control example, indicating that while the geopolymer self-healing microcapsules have some repair effect without zeolite, their effect is negligible compared to geopolymer microcapsules containing zeolite.

[0160] Subsequent permeability experiments showed that, compared to the control group, the permeability of Examples 1-8 was significantly reduced after the addition of self-healing microcapsules. This result indicates that the zeolite-containing geopolymer microcapsules, upon breaking down during crack propagation, release free water, promoting the hydration of unhydrated cementitious materials to generate hydration products such as C-(A)-SH gel, filling the cracks, densifying the matrix, and significantly reducing permeability. In contrast, the zeolite-free self-healing microcapsules (Application Example 9) were easily broken down and failed during stirring. Although they showed some repair effect and reduced permeability, the repair efficacy decreased. This further confirms that the geopolymer self-healing microcapsules have a significant repair effect on cracks, and their repair effect improves over time.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A geopolymer self-healing capsule, characterized in that, The raw materials used, by weight, are: 10-20 parts acrylic acid, 4-8 parts sodium hydroxide, 5-10 parts zeolite, 0.03-0.2 parts initiator, 0.01-0.1 parts crosslinking agent, 30-60 parts capsule wall material, 10-20 parts emulsifier, 100-200 parts organic solvent, 150-250 parts dispersant, and 20-50 parts deionized water; The preparation process includes the following steps: (1) Weigh each raw material according to the proportion; (2) Add sodium hydroxide to deionized water to prepare an alkaline solution; (3) Add the alkaline solution to the acrylic acid under ice-water bath conditions and stir. Then add the crosslinking agent and stir. Finally, add the zeolite and stir to obtain a solution. (4) Disperse the solution obtained in step (3) by ultrasonication, then add the initiator and stir, and then place it in a constant temperature water bath at 60-80℃ for reaction; (5) Dry the finished product from step (4) and grind it to obtain the core; (6) Add the capsule wall material and part of the emulsifier to the organic solvent and stir; (7) Add the capsule core obtained in step (5) to the mixture prepared in step (6) and stir; (8) Add the remaining emulsifier to the dispersant and stir; (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir until the organic solvent is completely evaporated. Then filter, dry, and finally collect the geopolymer self-healing microcapsules.

2. The geopolymer self-healing capsule according to claim 1, characterized in that: The size of the geopolymer self-healing microcapsules is 200-300 μm.

3. The geopolymer self-healing capsule according to claim 1, characterized in that: The initiator is potassium persulfate and / or sodium persulfate.

4. The geopolymer self-healing capsule according to claim 1, characterized in that: The crosslinking agent is N,N'-methylenebisacrylamide or divinylbenzene.

5. The geopolymer self-healing capsule according to claim 1, characterized in that: The emulsifier is one or more of Tween 20, Tween 40, Tween 80, and Span 80.

6. The geopolymer self-healing capsule according to claim 1, characterized in that: The organic solvent is one or more of anhydrous ethanol, dichloromethane, chloroform, and toluene; the dispersant is soybean oil or methyl silicone oil.

7. A method for preparing the geopolymer self-healing capsule according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Weigh each raw material according to the proportion; (2) Add sodium hydroxide to deionized water to prepare an alkaline solution; (3) Add the alkaline solution to the acrylic acid under ice-water bath conditions and stir. Then add the crosslinking agent and stir. Finally, add the zeolite and stir to obtain a solution. (4) Disperse the solution obtained in step (3) by ultrasonication, then add the initiator and stir, and then place it in a constant temperature water bath at 60-80℃ for reaction; (5) Dry the finished product from step (4) and grind it to obtain the core; (6) Add the capsule wall material and part of the emulsifier to the organic solvent and stir; (7) Add the capsule core obtained in step (5) to the mixture prepared in step (6) and stir; (8) Add the remaining emulsifier to the dispersant and stir; (9) Add the mixture prepared in step (7) to the mixture prepared in step (8), and heat and stir until the organic solvent is completely evaporated. Then filter, dry, and finally collect the geopolymer self-healing microcapsules.

8. The preparation method according to claim 7, characterized in that: In steps (3), (4), (6), (7), and (8), the stirring method is magnetic stirring, and the stirring speed is 200-600 r / min; in step (9), the heating and stirring method is constant temperature heating stirring, the stirring temperature is 60-80 ℃, and the stirring speed is 400-800 r / min.

9. The preparation method according to claim 7, characterized in that: In step (5), the drying process is carried out at 50-80 ℃ for 24-36 h; in step (9), the drying process is carried out at 50-70 ℃ for 12-18 h.

10. The application of the geopolymer self-healing capsule of claim 1 in repairing concrete cracks.

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