A concrete crack self-repairing additive and its preparation and application

Abstract

The present invention discloses a concrete crack self-repairing additive, belonging to the field of concrete additives. The concrete crack self-repairing additive comprises a material for concrete crack self-repair, sodium bicarbonate, calcium hydroxide, and triisopropanolamine. The concrete crack self-repairing material comprises an inner core and an outer shell surrounding the inner core. The inner core is porous solid particles filled with Debaryomyces hansenii, glucose, and sodium percarbonate, and the outer shell comprises dextrin and potassium dihydrogen phosphate. The present invention provides an additive with intelligent repair capabilities for concrete cracks and voids, overcoming the limitations of traditional expansion agents and waterproofing agents, which have limited functionality and poor crack repair effectiveness.

Description

Technical Field

[0001] The present invention relates to the field of concrete additives, and in particular to a concrete crack self-repairing additive and a preparation and application thereof. Background Art

[0002] As one of the most widely used civil engineering materials, concrete has the characteristics of easy plasticity, economy, safety, versatility and durability. However, concrete often cracks due to temperature changes, shrinkage, foundation deformation, steel corrosion and other reasons. Concrete with cracks poses a serious safety hazard. Existing expansion agents and waterproofing agents have a single function and poor effect on repairing concrete cracks. The repair of concrete cracks consumes a lot of manpower and material resources, and often some cracks are not easy to find, resulting in untimely repairs, which causes greater economic losses; some concrete cracks are not easy to repair alone, and often need to be repaired together with the adjacent concrete to achieve the crack repair, which cannot be repaired at a fixed point, resulting in waste of materials. Therefore, how to use microorganisms to invent a crack self-repairing concrete additive is the focus of the present invention. Summary of the Invention

[0003] To address the shortcomings of the above existing technologies, the present invention provides a self-repairing additive for concrete cracks, its preparation, and its application. By utilizing microbial technology, under certain triggering conditions, a certain amount of carbon dioxide is generated, which reacts with calcium hydroxide in the concrete to form calcium carbonate, which fills the cracks and repairs them. This is achieved specifically through the following techniques.

[0004] The present invention provides a material for self-repairing concrete cracks, comprising a core and a shell wrapping the core, wherein the core is porous solid particles filled with Debaryomyces hansenii, glucose and sodium percarbonate, and the shell comprises dextrin and potassium dihydrogen phosphate.

[0005] The Debaryomyces hansenii yeast of the present invention is an alkali-tolerant yeast that can adapt to environments with a pH of 4 to 12.5, and is most active at pH 6 to 11. When cracks appear in concrete, water penetrates the porous solid particles, and sodium percarbonate releases oxygen, activating the Debaryomyces hansenii to decompose glucose, releasing water and carbon dioxide. The carbon dioxide reacts with calcium hydroxide in the concrete to form calcium carbonate precipitates, which fill the cracks and increase the density of the concrete, thereby achieving self-repair of the cracks. Potassium dihydrogen phosphate, as a buffer and nutrient, can maintain a favorable acid-base environment for the Debaryomyces hansenii yeast, ensuring its activity and enabling it to quickly generate calcium carbonate precipitates, increasing the density of the concrete. As the density and alkalinity increase, the activity of the Debaryomyces hansenii yeast decreases to dormancy. When cracks appear and water penetrates, the alkalinity of the concrete at the cracks drops below 12.5, and the Debaryomyces hansenii yeast is reactivated, decomposing to produce carbon dioxide, which reacts with calcium in the concrete to repair the cracks. Debaryomyces hansenii acts as a trigger within concrete, triggered by cracks, leaks, or a drop in alkalinity. Once sufficient calcium carbonate is produced to fill all cracks and voids in the concrete, the yeast, consuming its oxygen and sugar sources, enters a dormant state again, remaining dormant until reactivated or until the oxygen and sugar sources are depleted. By utilizing microbial technology, this invention significantly enhances its intelligence and enables targeted crack repair.

[0006] Preferably, the porous solid particles are selected from at least one of foam ceramics, polystyrene and porous metal tin.

[0007] Preferably, the porous solid particles are 10-30 mesh porous solid particles with 10-100 μm micropores.

[0008] Preferably, the mass fraction of Debaryomyces hansenii in the Debaryomyces hansenii solution is 20-40%.

[0009] Preferably, the mass ratio of glucose to sodium percarbonate is (2.3-4.5):1.

[0010] Preferably, the mass ratio of dextrin to potassium dihydrogen phosphate is 1:(2-10).

[0011] Preferably, the mass ratio of the core to the shell is (1.5-4):1.

[0012] Preferably, the glucose is 200-300 mesh glucose crystal powder.

[0013] Preferably, the sodium percarbonate is 200-300 mesh sodium percarbonate crystalline powder.

[0014] Preferably, the dextrin is at least one of cyclodextrin and maltodextrin.

[0015] Preferably, the potassium dihydrogen phosphate is 80-150 mesh potassium dihydrogen phosphate crystalline powder.

[0016] The method for preparing the above-mentioned material for self-repairing concrete cracks comprises the following steps:

[0017] S1. Adding porous solid particles to a Debaryomyces hansenii solution for soaking for 24-25 hours, and then placing them at 23-26° C. and drying them with a continuous air flow of 5-6 m / s for 70-73 hours to obtain porous solid particles I.

[0018] S2, mixing glucose and sodium percarbonate to obtain a mixture; placing the porous solid particles I in step S1 into the mixture so that the mixture fully fills the voids in the porous solid particles, thereby obtaining porous solid particles II;

[0019] S3. Add dextrin and potassium dihydrogen phosphate to water to obtain dextrin mucus; place the porous solid particles II in step S2 in the dextrin mucus to obtain a material for self-repairing concrete cracks.

[0020] Preferably, in step S1, the mass ratio of the porous solid particles to the Debaryomyces hansenii solution is 1:(1-2).

[0021] Preferably, in step S2, the mass ratio of the porous solid particles I to the mixture is (2.3-9):1.

[0022] A concrete crack self-repairing additive comprises the above-mentioned material for concrete crack self-repairing.

[0023] Preferably, sodium bicarbonate, calcium hydroxide and triisopropanolamine are also included.

[0024] Preferably, the mass ratio of the material for self-repairing concrete cracks, sodium bicarbonate, calcium hydroxide and triisopropanolamine is (6-25):(2-15):(7-20):1.

[0025] Preferably, the sodium bicarbonate is 80-150 mesh sodium bicarbonate crystalline powder.

[0026] Preferably, the calcium hydroxide is 80-200 mesh calcium hydroxide crystalline powder.

[0027] Preferably, the triisopropanolamine is triisopropanolamine powder with a mass fraction of 98%.

[0028] The above concrete crack self-repairing additive is used to mix the material for concrete crack self-repairing, sodium bicarbonate, calcium hydroxide and triisopropanolamine to obtain a mixture, which is then added to concrete.

[0029] Preferably, the amount of the concrete crack self-repairing additive added to the concrete is 1 to 2% based on the total mass of cement.

[0030] Compared with the prior art, the present invention is beneficial in that:

[0031] 1. The present invention provides an additive that can intelligently repair concrete cracks and voids, overcoming the problems of traditional expansion agents and waterproofing agents that have single functions and poor crack repair effects;

[0032] 2. When the concrete is added with the present invention, Debaryomyces hansenii can be activated no matter where cracks appear, thereby allowing the concrete to repair itself. That is, the additive of the present invention can not only achieve self-repair of concrete cracks, but also achieve fixed-point repair, greatly saving the cost of crack repair;

[0033] 3. The sodium bicarbonate of the present invention can slowly release carbon dioxide under the catalysis of triisopropanolamine. The carbon dioxide reacts with calcium hydroxide present in the concrete to generate calcium carbonate, further improving the density and anti-permeability performance of the concrete. DETAILED DESCRIPTION

[0034] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0035] A method for preparing a material for self-repairing concrete cracks, comprising the following steps:

[0036] S1. Adding porous solid particles to a Debaryomyces hansenii solution for soaking for 24-25 hours, and then placing them at 23-26° C. and drying them with a continuous air flow of 5-6 m / s for 70-73 hours to obtain porous solid particles I.

[0037] S2, mixing glucose and sodium percarbonate to obtain a mixture; placing the porous solid particles I in step S1 into the mixture so that the mixture fully fills the voids in the porous solid particles, thereby obtaining porous solid particles II;

[0038] S3. Add dextrin and potassium dihydrogen phosphate to water to obtain dextrin mucus; place the porous solid particles II in step S2 in the dextrin mucus to obtain a material for self-repairing concrete cracks.

[0039] Optionally, the porous solid particles are at least one of foam ceramics, polystyrene and porous metal tin.

[0040] Optionally, the mass ratio of the porous solid particles to the Debaryomyces hansenii solution is 1:(1-2).

[0041] Optionally, the mass fraction of Debaryomyces hansenii in the Debaryomyces hansenii solution is 20-40%.

[0042] Optionally, the particle size of the porous solid particles is 10-30 meshes.

[0043] Optionally, the mass ratio of glucose to sodium percarbonate is (2.3-4.5):1.

[0044] Optionally, the mass ratio of the porous solid particles I to the mixture is (2.3-9):1.

[0045] Optionally, the mass ratio of dextrin to potassium dihydrogen phosphate is 1:(2-10).

[0046] Optionally, the mass ratio of the core to the shell is (1.5-4):1.

[0047] Optionally, the porous solid particles are 10-30 mesh porous solid particles with 10-100 um micropores.

[0048] Optionally, the glucose is 200-300 mesh glucose crystal powder.

[0049] Optionally, the sodium percarbonate is 200-300 mesh sodium percarbonate crystalline powder.

[0050] Optionally, the dextrin is at least one of cyclodextrin and maltodextrin.

[0051] Optionally, the potassium dihydrogen phosphate is 80-150 mesh potassium dihydrogen phosphate crystalline powder.

[0052] A preparation method of a concrete additive comprises the following steps: uniformly mixing the above-mentioned material for self-repairing concrete cracks with sodium bicarbonate, calcium hydroxide and triisopropanolamine to obtain the concrete additive.

[0053] Preferably, the mass ratio of the material for self-repairing concrete cracks, sodium bicarbonate, calcium hydroxide and triisopropanolamine is (6-25):(2-15):(7-20):1.

[0054] Optionally, the sodium bicarbonate is 80-150 mesh sodium bicarbonate crystalline powder.

[0055] Optionally, the calcium hydroxide is 80-200 mesh calcium hydroxide crystalline powder.

[0056] Optionally, the triisopropanolamine is triisopropanolamine powder with a mass fraction of 98%.

[0057] The technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0058] The Debaryomyces hansenii used in the examples of the present invention is commercially available Debaryomyces hansenii.

[0059] Example 1

[0060] This embodiment provides a method for preparing a material for self-repairing concrete cracks, comprising the following steps:

[0061] S1. Add 20-mesh foam ceramic particles to a Debaryomyces hansenii solution and soak them in a mass ratio of 1:2. After soaking for 24 hours, place the particles in a 25°C oven-dried oven at a wind speed of 5 m / s for 72 hours to obtain foam ceramic particles I. The mass fraction of the Debaryomyces hansenii solution is 30%. The mass fraction of Debaryomyces hansenii in the Debaryomyces hansenii solution is 30%.

[0062] S2, mixing 75 parts by weight of glucose with 25 parts by weight of sodium percarbonate to obtain a mixture; taking 80 parts by weight of the foam ceramic particles I prepared in step S1 and placing them in 20 parts by weight of the above mixture so that the mixture fully fills the gaps between the foam ceramic particles, to obtain foam ceramic particles II;

[0063] S3. Add 10 parts by weight of dextrin and 40 parts by weight of potassium dihydrogen phosphate to 50 parts by weight of water to obtain dextrin mucus; take 70 parts by weight of the foam ceramic particles II in step S2 and place them in 30 parts by weight of the dextrin mucus to obtain a material for self-repair of concrete cracks.

[0064] This embodiment also provides a method for preparing a concrete crack self-repairing additive, comprising the following steps: mixing 40 parts by weight of the above-mentioned material for concrete crack self-repair with 20 parts by weight of sodium bicarbonate, 37 parts by weight of calcium hydroxide, and 3 parts by weight of triisopropanolamine to obtain the additive.

[0065] Example 2

[0066] This embodiment provides a method for preparing a material for self-repairing concrete cracks, comprising the following steps:

[0067] S1. Add 10-mesh foam ceramic particles to a Debaryomyces hansenii solution and soak them in a mass ratio of 1:2. After soaking for 24 hours, place the particles in a 25°C oven-dried oven at a wind speed of 5 m / s for 72 hours to obtain foam ceramic particles I. The mass fraction of the Debaryomyces hansenii solution is 20%. The mass fraction of Debaryomyces hansenii in the Debaryomyces hansenii solution is 20%.

[0068] S2, mixing 70 parts by weight of glucose with 30 parts by weight of sodium percarbonate to obtain a mixture; taking 70 parts by weight of the foam ceramic particles I in step S1 and placing them in 30 parts by weight of the above mixture so that the mixture fully fills the gaps between the foam ceramic particles, to obtain foam ceramic particles II;

[0069] S3. Add 5 parts by weight of dextrin and 30 parts by weight of potassium dihydrogen phosphate to 65 parts by weight of water to obtain dextrin mucus; take 60 parts by weight of the foam ceramic particles II in step S2 and place them in 40 parts by weight of the dextrin mucus to obtain a material for self-repair of concrete cracks.

[0070] This embodiment also provides a method for preparing a concrete crack self-repairing additive, comprising the following steps: mixing 30 parts by weight of the above-mentioned material for concrete crack self-repair with 30 parts by weight of sodium bicarbonate, 35 parts by weight of calcium hydroxide, and 5 parts by weight of triisopropanolamine to obtain the additive.

[0071] Example 3

[0072] This embodiment provides a method for preparing a material for self-repairing concrete cracks, comprising the following steps:

[0073] S1. Add 30-mesh foam ceramic particles to a Debaryomyces hansenii solution and soak them in a mass ratio of 1:2. After soaking for 24 hours, place the particles in a 25°C oven-dried oven at a wind speed of 5 m / s for 72 hours to obtain foam ceramic particles I. The mass fraction of the Debaryomyces hansenii solution is 40%. The mass fraction of Debaryomyces hansenii in the Debaryomyces hansenii solution is 40%.

[0074] S2, mixing 80 parts by weight of glucose with 20 parts by weight of sodium percarbonate to obtain a mixture; taking 90 parts by weight of the foam ceramic particles I prepared in step S1 and placing them in 10 parts by weight of the above mixture so that the mixture fully fills the gaps between the foam ceramic particles, to obtain foam ceramic particles II;

[0075] S3. Add 15 parts by weight of dextrin and 50 parts by weight of potassium dihydrogen phosphate to 35 parts by weight of water to obtain dextrin mucus; take 80 parts by weight of the foam ceramic particles II in step S2 and place them in 20 parts by weight of the dextrin mucus to obtain a material for self-repair of concrete cracks.

[0076] This embodiment also provides a method for preparing a concrete crack self-repairing additive, comprising the following steps: mixing 50 parts by weight of the above-mentioned material for concrete crack self-repair with 10 parts by weight of sodium bicarbonate, 38 parts by weight of calcium hydroxide, and 2 parts by weight of triisopropanolamine to obtain the additive.

[0077] Comparative Example 1

[0078] This comparative example is basically the same as Example 1, except that Debaryomyces hansenii is replaced with commercially available common yeast powder (such as Angel Yeast).

[0079] Comparative Example 2

[0080] This comparative example is basically the same as Example 1, except that potassium dihydrogen phosphate is replaced by dextrin of equal mass.

[0081] Comparative Example 3

[0082] This comparative example is basically the same as Example 1, except that the amount of potassium dihydrogen phosphate is reduced. That is, in step S2 of the method for preparing the material for self-repairing concrete cracks, 6 parts by weight of dextrin and 29 parts by weight of potassium dihydrogen phosphate are added to 65 parts by weight of water to obtain dextrin mucus.

[0083] Comparative Example 4

[0084] This comparative example is substantially the same as Example 1, except that sodium bicarbonate is replaced by an equal weight of triisopropanolamine.

[0085] Comparative Example 5

[0086] This comparative example is substantially the same as Example 1, except that triisopropanolamine is replaced by an equal weight of sodium bicarbonate.

[0087] Performance Testing

[0088] The concrete crack self-repairing additives of Examples 1-3 and Comparative Examples 1-5 were tested for 28-day compressive strength ratio, 48-hour water absorption ratio, and penetration height ratio in accordance with the relevant provisions of JC474-2008, "Mortar and Concrete Waterproofing Agents." The crack self-repairing force ratio performance was also tested in accordance with the relevant provisions of T / CECS913-2021, "Test Methods for Self-Repairing Properties of Cement Concrete." The test results are shown in Table 1.

[0089] Table 1 Performance test results of Examples 1 to 3 and Comparative Examples 1 to 5

[0090]

[0091] As can be seen from Table 1, Examples 1 to 3 all meet the requirements of the compressive strength ratio, 48h water absorption ratio, and penetration height ratio in JC474-2008 "Mortar and Concrete Waterproofing Agent", and the effective concentration of Debaryomyces hansenii in Example 3 is the highest, so its index detection value is also the highest. Similarly, the crack self-repairing force ratio tested in accordance with T / CECS913-2021 "Test Method for Self-Repairing Performance of Cement Concrete" is also the highest, followed by Example 1 and Example 2, but all meet the standards and usage requirements.

[0092] Compared with Example 1, the compressive strength and crack self-repairing ability of Comparative Example 1 decreased significantly, while the 48h water absorption ratio and penetration height ratio were both higher. This is because Comparative Example 1 uses ordinary yeast. Although it is protected by potassium dihydrogen phosphate buffer, when the alkalinity of the environment exceeds the buffer zone, the biological activity of the ordinary yeast will drop significantly, the ability to produce carbon dioxide will be reduced, and it cannot generate sufficient calcium carbonate for filling. Therefore, the prepared concrete does not meet the standards.

[0093] Compared with Example 1, the compressive strength and crack self-healing ability of Comparative Example 2 decreased significantly, while the 48-hour water absorption ratio and penetration height were relatively high. This is because modified dextrin was not used to encapsulate the porous solid particles in Comparative Example 2, i.e., the foam ceramic particles lost the protective buffer of potassium dihydrogen phosphate. Although Debaryomyces hansenii has strong alkali resistance, as the hydration reaction proceeds, when the pH value inside the concrete reaches 12.5 or above, the biological activity of Debaryomyces hansenii will be greatly weakened, and it may even be killed by the high alkaline environment. Therefore, the relevant index values ​​of the prepared concrete cannot meet the requirements of the relevant standards.

[0094] Compared with Example 1, the compressive strength and crack self-healing ability ratio of Comparative Example 3 still showed significant decreases, while the 48-hour water absorption ratio and penetration height ratio were still high. This is because the amount of potassium dihydrogen phosphate used in Comparative Example 3 was too small. As the hydration reaction proceeded, the protective effect of potassium dihydrogen phosphate weakened, the activity of Debaryomyces hansenii decreased, the reaction terminated, and insufficient calcium carbonate was generated to fill the cracks. As a result, the performance indicators of the resulting concrete were unsatisfactory.

[0095] Compared with Example 1, the compressive strength and crack self-repairing ability ratio of Comparative Examples 4 to 5 are significantly reduced, and the 48h water absorption ratio and penetration height ratio are significantly increased. The reason may be that in Comparative Example 4, no sodium bicarbonate is used, but only triisopropanolamine is used, and there is no sodium bicarbonate, that is, there is no raw material for generating carbon dioxide, and triisopropanolamine has no catalytic object; in Comparative Example 5, no triisopropanolamine is used, and the release rate of carbon dioxide is extremely slow when sodium bicarbonate is not catalyzed by triisopropanolamine; Comparative Examples 4 to 5 cannot produce more carbon dioxide, so when cracks appear in the concrete, no more calcium carbonate can be produced to fill the cracks, resulting in unqualified relevant performance indicators of the concrete.

[0096] The above specific embodiments describe the implementation of the present invention in detail, but the present invention is not limited to the specific details of the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

Claims

1. A material for self-repair of concrete cracks, characterized in that: The invention comprises a core and a shell encapsulating the core, wherein the core is porous solid particles filled with Debaryomyces hansenii, glucose and sodium percarbonate, the porous solid particles being selected from at least one of foam ceramics, polystyrene and porous metal tin, and the shell comprises dextrin and potassium dihydrogen phosphate; The method for preparing the material for self-repairing concrete cracks comprises the following steps: S1. Adding porous solid particles to a Debaryomyces hansenii solution for soaking for 24-25 hours, and then placing them at 23-26° C. and drying them with a continuous air flow of 5-6 m / s for 70-73 hours to obtain porous solid particles I. S2, mixing glucose and sodium percarbonate to obtain a mixture; placing the porous solid particles I in step S1 into the mixture so that the mixture fully fills the voids in the porous solid particles, thereby obtaining porous solid particles II; S3. Add dextrin and potassium dihydrogen phosphate to water to obtain dextrin mucus; place the porous solid particles II in step S2 in the dextrin mucus to obtain a material for self-repairing concrete cracks.

2. The material for self-repairing concrete cracks according to claim 1, characterized in that: The mass ratio of the glucose to the sodium percarbonate is (2.3~4.5):

1.

3. The material for self-repairing concrete cracks according to claim 1, characterized in that: The mass ratio of the dextrin to the potassium dihydrogen phosphate is 1:(2~10).

4. The material for self-repairing concrete cracks according to claim 1, characterized in that: The mass ratio of the core to the shell is (1.5-4):

1.

5. The material for self-repairing concrete cracks according to claim 1, characterized in that: The dextrin is at least one of cyclodextrin and maltodextrin.

6. A concrete crack self-repairing additive, characterized in that: The material for self-repairing concrete cracks according to any one of claims 1 to 5 further comprises sodium bicarbonate, calcium hydroxide and triisopropanolamine.

7. The concrete crack self-repairing additive according to claim 6, characterized in that: The mass ratio of the material for self-repairing concrete cracks, the sodium bicarbonate, the calcium hydroxide and the triisopropanolamine is (6-25):(2-15):(7-20):

1.

8. The use of the concrete crack self-repairing additive according to claim 6, characterized in that: The amount of the concrete crack self-repairing additive in concrete is 1-2% based on the total mass of cement.

Images