Geopolymer self-repairing microcapsule as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of concrete crack repairing materials, particularly relates to a geopolymer self-repairing microcapsule, and also relates to a preparation method and application of the geopolymer self-repairing microcapsule. The geopolymer self-repairing microcapsule is prepared from the following raw materials: acrylic acid, sodium hydroxide, zeolite, an initiator, a cross-linking agent, a capsule wall material, an emulsifier, an organic solvent and a dispersing agent. When cracks exist, the super absorbent resin can release water, the cracks in the geopolymer continue to be hydrated, the cracks are repaired, interface bonding is tighter through the repairing mode, and the interfaces are not prone to cracking when bearing loads again.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete crack repair materials, and specifically relates to a geopolymer self-repairing microcapsule, and also relates to a preparation method and application of the geopolymer self-repairing microcapsule. Background Art

[0002] Geopolymers have the characteristics of fast setting and early strength, good thermal stability, strong interface bonding ability, and a wide range of sources. They have low carbon emissions during the preparation process and are more in line with environmental protection concepts. They are one of the preferred materials to replace ordinary concrete. However, due to their high brittleness and easy cracking, geopolymers are subject to many restrictions in practical applications. Although polymer-modified geopolymers can effectively prevent the development of cracks, the cracks generated by geopolymers under long-term loads still sharply shorten the service life of geopolymers.

[0003] Therefore, the early self-repair of microcracks is crucial to improving the engineering application performance of geopolymer materials. The current microcapsule self-repair technology, both at home and abroad, mostly adopts the method of encapsulating the repair liquid, dissolving the curing agent in the mixing water and adding it to the geopolymer. However, the curing agent will gradually become ineffective over time, and the microcapsules are easy to break during the mixing process of the geopolymer, which seriously affects the effect of self-repair. At the same time, most of the existing methods for repairing cracks are to use a repair agent and a curing agent to cross-link and solidify to fill the cracks. This method will have an interface between the polymer and the geopolymer base, and the interface connection is not tight. When it is subjected to load again, the interface is prone to cracking. At the same time, the curing agent is added to the geopolymer matrix. Most of these curing agents are toxic, and long-term contact will cause harm to the human body and pollute the environment. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a geopolymer self-repairing microcapsule, and also to provide a preparation method and application of the geopolymer self-repairing microcapsule.

[0005] The technical solution adopted by the present invention is:

[0006] A geopolymer self-repairing capsule comprises the following raw materials, measured in parts by weight: 10-20 parts of acrylic acid, 4-8 parts of sodium hydroxide, 5-10 parts of zeolite, 0.03-0.2 parts of initiator, 0.01-0.1 parts of cross-linking agent, 30-60 parts of capsule wall material, 10-20 parts of emulsifier, 100-200 parts of organic solvent, 150-250 parts of dispersant and 20-50 parts of 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 cross-linking 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 of geopolymer self-repairing capsule comprises the following steps:

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

[0015] (2) adding sodium hydroxide into deionized water and stirring for 1-3 minutes to prepare alkaline solution;

[0016] (3) adding alkali solution to acrylic acid in an ice water bath and stirring for 2-8 minutes, then adding a crosslinking agent and stirring for 5-10 minutes, and finally adding zeolite and stirring for 1-3 minutes to obtain a solution;

[0017] (4) ultrasonically dispersing the solution obtained in step (3) for 5-10 minutes, then adding the initiator and stirring for 2-8 minutes, and then placing it in a constant temperature water bath at 60-80° C. for 1-3 hours to react;

[0018] (5) drying the finished product of step (4), grinding it in a mortar for 10-20 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 100-200 μm;

[0019] (6) adding the capsule wall material and the emulsifier into the organic solvent and stirring for 5-10 minutes;

[0020] (7) adding the capsule core obtained in step (5) to the mixed solution prepared in step (6) and stirring for 5-10 minutes;

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

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

[0023] The stirring in steps (3), (4), (6), (7) and (8) is carried out using a magnetic stirrer at a stirring speed of 200-600 r / min.

[0024] The heating and stirring method in step (9) is stirring with a constant temperature heating stirrer, the stirring temperature is 60-80°C, and the stirring speed is 400-800r / min.

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

[0026] In the step (9), the drying is performed at 50-70° C. for 12-18 hours.

[0027] The application of the geopolymer self-repairing capsule in repairing concrete cracks.

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

[0029] 1. In the present invention, acrylic acid, sodium hydroxide, initiator and crosslinking agent in the capsule core are chemically synthesized into a super absorbent resin (SAP) in the porous zeolite pores. Under the action of the initiator and the crosslinking agent, the acrylic acid monomer undergoes a polymerization reaction: n(CH 2 =CHCOOH) → [-CH 2 -CHCOO-] n Zeolite acts as the skeleton of SAP, which increases the strength of the capsule core, avoids the failure of the microcapsules caused by the breakage of the microcapsules during the stirring process, and greatly improves the repair efficiency of the microcapsules.

[0030] 2. In the present invention, the geopolymer repair capsule will not become ineffective over time during use. When the geopolymer repair capsule is subjected to load and microcracks are generated, the microcapsules are broken, and the pre-stored water inside the SAP is released into the microcracks, which further hydrates the cracks to repair the cracks. In addition, when the environment is humid, the SAP in the cracks will absorb water and expand rapidly to fill the cracks, and release more water in the cracks to promote further hydration of the geopolymer.

[0031] 3. The capsule core skeleton of the present invention is zeolite, and the pores are filled with highly absorbent resin. When cracks exist, the highly absorbent resin will release water to continue hydrating the cracks in the geopolymer and repair the cracks. This repair method makes the interface bond more tightly, and the interface is not easy to crack when it is subjected to load again.

[0032] 4. The present invention uses highly absorbent resin to absorb water and waterproof, which further hydrates the cracks and expands and fills them. It does not require the use of toxic curing agents and will not cause pollution to the environment. This method is safer and more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a picture of the self-repairing microcapsule in Example 1.

[0034] Figure 2This is a picture of the self-repairing microcapsule in Example 2.

[0035] Figure 3 This is a picture of the self-repairing microcapsule in Example 3.

[0036] Figure 4 This is a picture of the self-repairing microcapsule of Example 4.

[0037] Figure 5 This is a picture of the self-repairing microcapsule of Example 5.

[0038] Figure 6 This is a picture of the self-repairing microcapsule of Example 6.

[0039] Figure 7 This is a picture of the self-repairing microcapsule of Example 7.

[0040] Figure 8 This is a picture of the self-repairing microcapsule of Example 8.

[0041] Fig. 9 This is a picture of the self-repairing microcapsule of Example 9. DETAILED DESCRIPTION

[0042] The specific implementation modes of the present invention are described below in conjunction with examples. However, the following examples are only used to illustrate the present invention in detail and are not intended to limit the scope of the present invention in any way.

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

[0044] Embodiment 1:

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

[0046] The microcapsules were prepared by the following method:

[0047] (1) Weigh the raw materials according to quantity;

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

[0049] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 2 minutes, then adding N,N'-methylenebisacrylamide and stirring for 5 minutes, and finally adding zeolite and stirring for 1 minute;

[0050] (4) ultrasonically dispersing the solution obtained in step (3) for 5 minutes, then adding potassium persulfate and stirring for 2 minutes, and then placing it in a constant temperature water bath at 60° C. for 1 hour to react;

[0051] (5) drying the finished product in a drying oven at 50° C. for 24 h, grinding it in a mortar for 10 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 100 μm;

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

[0053] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 5 minutes;

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

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

[0056] Example 2

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

[0058] The microcapsules were prepared by the following method:

[0059] (1) Weigh the raw materials according to quantity;

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

[0061] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 3 minutes, then adding divinylbenzene and stirring for 6 minutes, and finally adding zeolite and stirring for 2 minutes;

[0062] (4) ultrasonically dispersing the solution obtained in step (3) for 6 minutes, then adding sodium persulfate and stirring for 3 minutes, and then placing it in a constant temperature water bath at 70° C. for 2 hours to react;

[0063] (5) drying the finished product in a drying oven at 60° C. for 26 h, grinding it in a mortar for 15 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 150 μm;

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

[0065] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 6 minutes;

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

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

[0068] Example 3

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

[0070] The microcapsules were prepared by the following method:

[0071] (1) Weigh the raw materials according to quantity;

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

[0073] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 7 minutes, then adding N,N'-methylenebisacrylamide and stirring for 8 minutes, and finally adding zeolite and stirring for 2 minutes;

[0074] (4) ultrasonically dispersing the solution obtained in step (3) for 8 minutes, then adding potassium persulfate and stirring for 6 minutes, and then placing it in a constant temperature water bath at 70° C. for 2 hours to react;

[0075] (5) drying the finished product in a drying oven at 70° C. for 30 h, grinding it in a mortar for 16 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 200 μm;

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

[0077] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 8 minutes;

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

[0079] (9) Add the mixed solution prepared in step (7) to the mixed solution 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 to obtain the geopolymer self-healing microcapsules.

[0080] Example 4

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

[0082] The microcapsules were prepared by the following method:

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

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

[0085] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 8 minutes, then adding divinylbenzene and stirring for 10 minutes, and finally adding zeolite and stirring for 3 minutes;

[0086] (4) ultrasonically dispersing the solution obtained in step (3) for 10 minutes, then adding potassium persulfate and stirring for 8 minutes, and then placing it in a constant temperature water bath at 80° C. for 3 hours to react;

[0087] (5) drying the finished product in a drying oven at 80° C. for 36 h, grinding it in a mortar for 20 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 200 μm;

[0088] (6) Add ethyl cellulose and Span 80 into the organic solvent and stir for 10 minutes;

[0089] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 10 minutes;

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

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

[0092] Example 5

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

[0094] The microcapsules were prepared by the following method:

[0095] (1) Weigh the raw materials according to quantity;

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

[0097] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 3 minutes, then adding divinylbenzene and stirring for 6 minutes, and finally adding zeolite and stirring for 2 minutes;

[0098] (4) ultrasonically dispersing the solution obtained in step (3) for 6 minutes, then adding sodium persulfate and stirring for 3 minutes, and then placing it in a constant temperature water bath at 70° C. for 2 hours to react;

[0099] (5) drying the finished product in a drying oven at 60° C. for 26 h, grinding it in a mortar for 15 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 150 μm;

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

[0101] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 5 minutes;

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

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

[0104] Example 6

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

[0106] The microcapsules were prepared by the following method:

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

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

[0109] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 8 minutes, then adding divinylbenzene and stirring for 10 minutes, and finally adding zeolite and stirring for 3 minutes;

[0110] (4) ultrasonically dispersing the solution obtained in step (3) for 10 minutes, then adding potassium persulfate and stirring for 8 minutes, and then placing it in a constant temperature water bath at 80° C. for 3 hours to react;

[0111] (5) drying the finished product in a drying oven at 80° C. for 36 h, grinding it in a mortar for 20 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 200 μm;

[0112] (6) Add ethyl cellulose and Span 80 into the organic solvent and stir for 10 minutes;

[0113] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 10 minutes;

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

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

[0116] Example 7

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

[0118] The microcapsules were prepared by the following method:

[0119] (1) Weigh the raw materials according to quantity;

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

[0121] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 2 minutes, then adding N,N'-methylenebisacrylamide and stirring for 5 minutes, and finally adding zeolite and stirring for 1 minute;

[0122] (4) ultrasonically dispersing the solution obtained in step (3) for 5 minutes, then adding potassium persulfate and stirring for 2 minutes, and then placing it in a constant temperature water bath at 60° C. for 1 hour to react;

[0123] (5) drying the finished product in a drying oven at 50° C. for 24 h, grinding it in a mortar for 10 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 100 μm;

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

[0125] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 7 minutes;

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

[0127] (9) Add the mixed solution prepared in step (7) to the mixed solution prepared in step 8), and heat and stir (70° C., 700 r / min) for 2 h until the anhydrous ethanol is completely evaporated, then filter, wash 3 times with anhydrous ethanol, dry, and finally collect to obtain the geopolymer self-healing microcapsules.

[0128] Example 8

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

[0130] The microcapsules were prepared by the following method:

[0131] (1) Weigh the raw materials according to quantity;

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

[0133] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 7 minutes, then adding N,N'-methylenebisacrylamide and stirring for 8 minutes, and finally adding zeolite and stirring for 2 minutes;

[0134] (4) ultrasonically dispersing the solution obtained in step (3) for 8 minutes, then adding potassium persulfate and stirring for 6 minutes, and then placing it in a constant temperature water bath at 70° C. for 2 hours to react;

[0135] (5) drying the finished product in a drying oven at 70° C. for 30 h, grinding it in a mortar for 16 min, and then sieving it to obtain a zeolite-superabsorbent resin capsule core with a particle size of 200 μm;

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

[0137] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 8 minutes;

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

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

[0140] Example 9

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

[0142] The microcapsules were prepared by the following method:

[0143] (1) Weigh the raw materials according to quantity;

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

[0145] (3) adding sodium hydroxide solution to acrylic acid in an ice-water bath and stirring for 3 minutes, and then adding divinylbenzene and stirring for 6 minutes;

[0146] (4) ultrasonically dispersing the solution obtained in step (3) for 6 minutes, then adding sodium persulfate and stirring for 3 minutes, and then placing it in a constant temperature water bath at 70° C. for 2 hours to react;

[0147] (5) drying the finished product in a drying oven at 60° C. for 26 h, grinding it in a mortar for 15 min, and then sieving it to obtain a super absorbent resin capsule core with a particle size of 150 μm;

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

[0149] (7) adding the sample obtained in step (5) to the mixed solution prepared in step (6) and stirring for 6 minutes;

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

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

[0152] The geopolymer self-repairing microcapsules prepared in Examples 1-9 were added to the geopolymer at 5% of the mass of the gelling material. The geopolymer mix ratio was: 500g fly ash, 500g slag, 120g alkali activator, and 350g water. The alkali activator was a mixture of water glass and sodium hydroxide, and the modulus of the alkali activator was adjusted to 1.4. 2 O content is 7%. A blank geopolymer was used as the control group.

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

[0154] Table 1 Comparative Examples 1-9 and Comparative Examples 7d, 28d and Pre-compression Crack Compressive Strength

[0155]

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

[0157] 3d permeability (mD) 7d permeability (mD) 28d permeability (mD) 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 above table show that adding the self-repairing capsules of the present invention to the geopolymer has no adverse effect on the 7d and 28d compressive strength of the test block, which is equivalent to the compressive strength of the blank geopolymer in the control example. The compressive strength of the test block after pre-compression of the crack by adding the self-repairing capsules is greater than that of the test block without adding microcapsules, indicating that the self-repairing microcapsules of the geopolymer have a significant repairing effect on the cracks.

[0159] When no zeolite is added (Application Example 9), most of the microcapsules are broken during the geopolymer stirring and molding process. The broken microcapsules absorb water and swell, resulting in failure, and the working performance of the geopolymer decreases. After the geopolymer is molded, its pre-compression crack compressive strength and permeability at each age are comparable to those of the control example, indicating that when no zeolite is added, the geopolymer self-repairing microcapsules have a certain repair effect, but compared with the geopolymer microcapsules containing zeolite, its effect is very small.

[0160] It can be seen from the subsequent permeability experiment that the permeability of Examples 1-8 is significantly reduced after the addition of self-repairing microcapsules compared to the control group. This result shows that after the zeolite-containing geopolymer microcapsules are broken during the crack expansion process, free water is released, which promotes the hydration of unhydrated gelling materials to generate hydration products such as C-(A)-SH gel to fill the cracks and compact the matrix, which significantly reduces the permeability. The self-repairing microcapsules that do not contain zeolite (Application Example 9) are very easy to break and fail during the stirring process. Although they have a certain repair effect and reduce the permeability, the repair effect is reduced. Once again, it is confirmed that the geopolymer self-repairing microcapsules have a significant repair effect on cracks, and their repair effect is better over time.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A geopolymer self-repairing capsule, characterized in that: The raw materials used are, by weight, 10-20 parts of acrylic acid, 4-8 parts of sodium hydroxide, 5-10 parts of zeolite, 0.03-0.2 parts of initiator, 0.01-0.1 parts of crosslinking agent, 30-60 parts of capsule wall material, 10-20 parts of emulsifier, 100-200 parts of organic solvent, 150-250 parts of dispersant and 20-50 parts of deionized water.

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

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

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

5. The geopolymer self-repairing 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-repairing 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-repairing capsule according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Weigh the raw materials according to the proportion; (2) adding sodium hydroxide into deionized water to prepare alkali solution; (3) adding an alkali solution to acrylic acid in an ice-water bath and stirring, then adding a cross-linking agent and stirring, and finally adding zeolite and stirring to obtain a solution; (4) ultrasonically dispersing the solution obtained in step (3), then adding the initiator thereto and stirring, and then placing the solution in a constant temperature water bath at 60-80° C. for reaction; (5) drying the finished product of step (4) and grinding it to obtain a capsule core; (6) adding capsule wall material and part of emulsifier into organic solvent and stirring; (7) adding the capsule core obtained in step (5) to the mixed solution prepared in step (6) and stirring; (8) adding the remaining emulsifier to the dispersant and stirring; (9) adding the mixed solution prepared in step (7) to the mixed solution prepared in step (8), heating and stirring at the same time until the organic solvent is completely volatilized, then filtering, drying, and finally collecting to obtain the geopolymer self-healing microcapsules.

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

9. The preparation method according to claim 7, characterized in that: In the step (5), the drying is performed at 50-80° C. for 24-36 hours; and in the step (9), the drying is performed at 50-70° C. for 12-18 hours.

10. Use of the geopolymer self-repairing capsule according to claim 1 in repairing concrete cracks.

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