A concrete penetrating crystallization self-healing material

Abstract

This invention discloses a concrete penetrating crystallization self-healing material, comprising the following raw materials in parts by weight: 30-40 parts silicate cement, 10-15 parts quartz sand, 5-10 parts aluminum silicate, 2-5 parts sodium citrate, 1-2 parts nano-silica, 3-5 parts fluorinated halloysite nanotubes, 2-6 parts modified calcium hydroxide, 2-5 parts surfactant, and 0.1-0.2 parts cellulose. The concrete penetrating crystallization self-healing material of this invention enables repaired concrete to maintain good mechanical strength and impermeability, exhibiting excellent self-healing effects.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a concrete penetrating crystallization self-healing material. Background Technology

[0002] Concrete is one of the most commonly used building materials, widely applied in civil and military structures. During use, concrete is susceptible to micro-cracks due to various factors such as temperature, humidity, and load. These micro-cracks can develop into larger cracks, even leading to structural cracking, deformation, and damage, posing safety hazards to construction projects. To address the cracking problem and extend the service life of concrete, self-healing technology has emerged. Currently, self-healing materials for concrete mainly include microcapsules and crystalline self-healing materials. Among them, penetrating crystalline self-healing materials work by catalyzing and activating the continued hydration of incompletely hydrated cement particles in the concrete, generating new crystals at the surface or internal cracks to fill them, thus achieving the self-healing function of concrete. However, the mechanical strength and impermeability of concrete after penetrating crystalline self-healing are still not ideal, necessitating the development of concrete penetrating crystalline self-healing materials that can further enhance the self-healing ability of concrete, especially improving its mechanical strength. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a concrete penetration crystallization self-healing material.

[0004] The present invention proposes a concrete penetrating crystallization self-healing material, comprising the following raw materials in parts by weight: 30-40 parts silicate cement, 10-15 parts quartz sand, 5-10 parts aluminum silicate, 2-5 parts sodium citrate, 1-2 parts nano silica, 3-5 parts fluorinated halloysite nanotubes, 2-6 parts modified calcium hydroxide, 2-5 parts surfactant, and 0.1-0.2 parts cellulose.

[0005] Preferably, the method for preparing the fluorinated halloysite nanotubes includes the following steps:

[0006] (1) Add halloysite nanotubes to sodium hydroxide solution, heat treatment, then centrifuge, wash, dry, calcine at high temperature, and cool to obtain activated halloysite nanotubes;

[0007] (2) The activated halloysite nanotubes are mixed with a saturated sodium fluoride aqueous solution, and then left to stand under vacuum for a period of time before drying to obtain fluorinated halloysite nanotubes.

[0008] Preferably, in step (1), the concentration of the sodium hydroxide solution is 0.5-1 mol / L, the heating temperature is 60-90℃, and the heating time is 2-3 h.

[0009] Preferably, in step (1), the high-temperature calcination temperature is 500-700℃ and the time is 1-2h.

[0010] Preferably, in step (2), the mass ratio of the activated halloysite nanotubes to the saturated sodium fluoride aqueous solution is 1:(0.1-0.2).

[0011] Preferably, the halloysite nanotubes have a length of 0.5-2 μm.

[0012] Preferably, the modified calcium hydroxide is prepared by mixing stearic acid, silane coupling agent KH-560 and calcium oxide, adding water at 70-80°C, stirring for 1-2 hours, and then filtering and drying to obtain the product.

[0013] Preferably, the mass ratio of stearic acid, silane coupling agent KH-560 to calcium oxide is (0.5-1):(1-1.5):10.

[0014] Preferably, the surfactant is composed of polyethylene glycol and sodium dodecyl sulfonate in a mass ratio of 1:(1-3).

[0015] Preferably, the cellulose is at least one of hydroxyethyl cellulose, hydroxymethylpropyl cellulose, and carboxymethyl cellulose.

[0016] The beneficial effects of this invention are as follows:

[0017] The present invention relates to a concrete penetrating crystallizing self-healing material, wherein aluminum silicate and sodium citrate can induce crystal formation and gel formation in concrete, promoting self-healing; fluorinated halloysite nanotubes are halloysite nanotubes that have been alkali-activated and treated at high temperatures to load fluoride ions, and their surfaces have active silica-alumina components that can promote crystal formation in concrete, generating crystals with a network skeleton in the concrete, improving concrete strength; fluoride ions can also react with calcium ions in the concrete to generate high-strength calcium fluoride, increasing concrete density and compressive strength; nano-silica can fill tiny gaps to form needle-like crystals, further improving the strength and impermeability of the concrete self-healing material; modified calcium hydroxide provides calcium ions, and due to the modification of its surface with stearic acid and silane coupling agent KH-560, it has a certain degree of hydrophobicity, allowing calcium ions to be released slowly during water seepage, enabling crystals and gels to penetrate deep into cracks and form more uniformly, thereby improving the strength of the concrete self-healing material; surfactants and cellulose can promote the penetration of the crystallizing self-healing active substances into concrete cracks and their uniform dispersion. The concrete penetrating crystallization self-healing material of the present invention can enable the repaired concrete to maintain good mechanical strength and impermeability, and has a very good self-healing effect. Detailed Implementation

[0018] The technical solution of the present invention will now be described in detail through specific embodiments.

[0019] Example 1

[0020] A concrete penetrating crystallization self-healing material comprises the following raw materials in parts by weight: 35 parts silicate cement, 12 parts quartz sand, 8 parts aluminum silicate, 3 parts sodium citrate, 1.5 parts nano silica, 4 parts fluorinated halloysite nanotubes, 3 parts modified calcium hydroxide, 4 parts surfactant, and 0.15 parts hydroxyethyl cellulose.

[0021] The surfactant is composed of polyethylene glycol and sodium dodecyl sulfonate in a mass ratio of 1:2.

[0022] The preparation method of fluorinated halloysite nanotubes includes the following steps:

[0023] (1) Halloysite nanotubes with a length of 0.5-2 μm were added to a sodium hydroxide solution with a concentration of 0.5 mol / L, heated at 80 °C for 2 h, then centrifuged, washed, dried, calcined at 650 °C for 2 h, and cooled to obtain activated halloysite nanotubes.

[0024] (2) The activated halloysite nanotubes were mixed with a saturated sodium fluoride aqueous solution at a mass ratio of 1:0.15, and then allowed to stand under vacuum for 1 hour before drying to obtain fluorinated halloysite nanotubes.

[0025] The modified calcium hydroxide is prepared by mixing stearic acid, silane coupling agent KH-560 and calcium oxide, adding water at 75°C, stirring for 1.5 hours, filtering and drying to obtain the product. The mass ratio of stearic acid, silane coupling agent KH-560 and calcium oxide is 0.8:1.2:10.

[0026] Example 2

[0027] A concrete penetrating crystallization self-healing material comprises the following raw materials in parts by weight: 30 parts silicate cement, 10 parts quartz sand, 5 parts aluminum silicate, 2 parts sodium citrate, 1 part nano silica, 3 parts fluorinated halloysite nanotubes, 2 parts modified calcium hydroxide, 2 parts surfactant, and 0.1 parts hydroxyethyl cellulose.

[0028] The surfactant is composed of polyethylene glycol and sodium dodecyl sulfonate in a mass ratio of 1:1.

[0029] The preparation method of fluorinated halloysite nanotubes includes the following steps:

[0030] (1) Halloysite nanotubes with a length of 0.5-2 μm were added to a sodium hydroxide solution with a concentration of 0.5 mol / L, heated at 60 °C for 3 h, then centrifuged, washed, dried, calcined at 500 °C for 2 h, and cooled to obtain activated halloysite nanotubes.

[0031] (2) The activated halloysite nanotubes were mixed with a saturated sodium fluoride aqueous solution at a mass ratio of 1:0.1, and then allowed to stand under vacuum for 1 hour before drying to obtain fluorinated halloysite nanotubes.

[0032] The modified calcium hydroxide is prepared by mixing stearic acid, silane coupling agent KH-560 and calcium oxide, adding water at 80°C, stirring for 1 hour, filtering and drying to obtain the product. The mass ratio of stearic acid, silane coupling agent KH-560 and calcium oxide is 0.5:1:10.

[0033] Example 3

[0034] A concrete penetrating crystallization self-healing material comprises the following raw materials in parts by weight: 40 parts silicate cement, 15 parts quartz sand, 10 parts aluminum silicate, 5 parts sodium citrate, 2 parts nano silica, 5 parts fluorinated halloysite nanotubes, 6 parts modified calcium hydroxide, 5 parts surfactant, and 0.2 parts hydroxyethyl cellulose.

[0035] The surfactant is composed of polyethylene glycol and sodium dodecyl sulfonate in a mass ratio of 1:3.

[0036] The preparation method of fluorinated halloysite nanotubes includes the following steps:

[0037] (1) Halloysite nanotubes with a length of 0.5-2 μm were added to a sodium hydroxide solution with a concentration of 1 mol / L, heated at 90 °C for 2 h, then centrifuged, washed, dried, calcined at 700 °C for 1 h, and cooled to obtain activated halloysite nanotubes.

[0038] (2) The activated halloysite nanotubes were mixed with a saturated sodium fluoride aqueous solution at a mass ratio of 1:0.2, and then allowed to stand under vacuum for 1 hour before drying to obtain fluorinated halloysite nanotubes.

[0039] The modified calcium hydroxide is prepared by mixing stearic acid, silane coupling agent KH-560 and calcium oxide, adding water at 70°C, stirring for 2 hours, filtering and drying to obtain the product. The mass ratio of stearic acid, silane coupling agent KH-560 and calcium oxide is 1:1.5:10.

[0040] Comparative Example 1

[0041] A concrete penetrating crystallization self-healing material comprises the following raw materials in parts by weight: 35 parts silicate cement, 12 parts quartz sand, 8 parts aluminum silicate, 3 parts sodium citrate, 1.5 parts nano silica, 4 parts halloysite nanotubes with a length of 0.5-2 μm, 3 parts modified calcium hydroxide, 4 parts surfactant, and 0.15 parts hydroxyethyl cellulose.

[0042] The surfactant is composed of polyethylene glycol and sodium dodecyl sulfonate in a mass ratio of 1:2.

[0043] The modified calcium hydroxide is prepared by mixing stearic acid, silane coupling agent KH-560 and calcium oxide, adding water at 75°C, stirring for 1.5 hours, filtering and drying to obtain the product. The mass ratio of stearic acid, silane coupling agent KH-560 and calcium oxide is 0.8:1.2:10.

[0044] Comparative Example 2

[0045] A concrete penetrating crystallization self-healing material comprises the following raw materials in parts by weight: 35 parts silicate cement, 12 parts quartz sand, 8 parts aluminum silicate, 3 parts sodium citrate, 1.5 parts nano silica, 4 parts fluorinated halloysite nanotubes, 3 parts calcium hydroxide, 4 parts surfactant, and 0.15 parts hydroxyethyl cellulose.

[0046] The surfactant is composed of polyethylene glycol and sodium dodecyl sulfonate in a mass ratio of 1:2.

[0047] The preparation method of fluorinated halloysite nanotubes includes the following steps:

[0048] (1) Halloysite nanotubes with a length of 0.5-2 μm were added to a sodium hydroxide solution with a concentration of 0.5 mol / L, heated at 80 °C for 2 h, then centrifuged, washed, dried, calcined at 650 °C for 2 h, and cooled to obtain activated halloysite nanotubes.

[0049] (2) The activated halloysite nanotubes were mixed with a saturated sodium fluoride aqueous solution at a mass ratio of 1:0.15, and then allowed to stand under vacuum for 1 hour before drying to obtain fluorinated halloysite nanotubes.

[0050] Test case

[0051] (1) The impermeability of the materials in Example 1 and Comparative Examples 1-2 was tested according to GB18445-2012 standard. The results are shown in Table 1:

[0052] Table 1

[0053]

[0054] As can be seen from Table 1, the self-healing material of the present invention has excellent anti-seepage repair performance.

[0055] (2) Concrete specimens were prepared according to GB18445-2012 standard and cured for 28 days. A compression test was then conducted using a rigid testing machine. The first compressive strength was recorded when the first visible crack appeared on the specimen surface. The specimens were then repaired using the self-healing materials from Examples 1 and 1-2. After 28 days of curing, a compression test was conducted using a rigid testing machine. The second compressive strength was recorded when the first visible crack appeared on the specimen surface. The compressive strength recovery rate was calculated as: Second compressive strength / First compressive strength × 100%. The test results are shown in Table 2.

[0056] Table 2

[0057] project Example 1 Comparative Example 1 Comparative Example 2 Compressive strength recovery rate (%) 95 84 92

[0058] As can be seen from Table 2, the repair material of the present invention can restore the mechanical properties of concrete well after concrete cracking, and has good repair ability.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A concrete penetrating crystallization self-healing material, characterized in that, The raw materials include the following parts by weight: 30-40 parts silicate cement, 10-15 parts quartz sand, 5-10 parts aluminum silicate, 2-5 parts sodium citrate, 1-2 parts nano silica, 3-5 parts fluorinated halloysite nanotubes, 2-6 parts modified calcium hydroxide, 2-5 parts surfactant, and 0.1-0.2 parts cellulose. The preparation method of the fluorinated halloysite nanotubes includes the following steps: (1) Add halloysite nanotubes to sodium hydroxide solution, heat treatment, then centrifuge, wash, dry, calcine at high temperature, and cool to obtain activated halloysite nanotubes; (2) The activated halloysite nanotubes are mixed with a saturated sodium fluoride aqueous solution, and then left to stand under vacuum for a period of time before drying to obtain fluorinated halloysite nanotubes. The modified calcium hydroxide is prepared by mixing stearic acid, silane coupling agent KH-560 and calcium oxide, adding water at 70-80℃, stirring for 1-2 hours, and then filtering and drying to obtain the product.

2. The concrete penetrating crystallization self-healing material according to claim 1, characterized in that, In step (1), the concentration of sodium hydroxide solution is 0.5-1 mol / L, the heating temperature is 60-90℃, and the heating time is 2-3 h; In step (1), the high-temperature calcination temperature is 500-700℃ and the time is 1-2h.

3. The concrete penetrating crystallization self-healing material according to claim 1, characterized in that, In step (2), the mass ratio of the activated halloysite nanotubes to the saturated sodium fluoride aqueous solution is 1:(0.1-0.2).

4. The concrete penetrating crystallization self-healing material according to claim 1, characterized in that, The halloysite nanotubes have a length of 0.5-2µm.

5. The concrete penetrating crystallization self-healing material according to claim 1, characterized in that, The mass ratio of stearic acid, silane coupling agent KH-560 and calcium oxide is (0.5-1):(1-1.5):

10.

6. The concrete penetrating crystallization self-healing material according to claim 1, characterized in that, The surfactant is composed of polyethylene glycol and sodium dodecyl sulfonate in a mass ratio of 1:(1-3).

7. The concrete penetrating crystallization self-healing material according to claim 1, characterized in that, The cellulose is at least one of hydroxyethyl cellulose, hydroxymethylpropyl cellulose, and carboxymethyl cellulose.

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