Self-healing quick-setting inorganic waterproof plugging material and preparation method thereof

Abstract

The invention relates to the field of building waterproof materials, in particular to a self-healing quick-setting inorganic waterproof plugging material and a preparation method thereof. The material comprises the following raw materials in parts by weight: 80-85 parts of sulphoaluminate cement, 4-6 parts of silica fume, 4-6 parts of mineral powder, 1-2 parts of calcium chloride, 0.5-1 part of lithium carbonate, 0.05-0.1 part of a water reducing agent, 0.07-0.15 part of hydroxypropyl methyl cellulose and 1-2 parts of a self-healing silicon-based activator. The self-healing type silicon-based activating agent is prepared from the following components in parts by weight: 0.9 to 1.2 parts of calcium hydroxide, 0.9 to 1.4 parts of magnesium fluosilicate, 0.3 to 0.5 part of nano active silicon and 1.1 to 1.4 parts of higher fatty acid salt. The material has the characteristics of rapid solidification, efficient self-healing and high impermeability.

Description

TECHNICAL FIELD

[0001] The application relates to the field of building waterproof materials, in particular to a self-healing and rapid-setting inorganic waterproof and leakage-stopping material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the fields of building, tunnel and underground engineering, the demand for waterproof and leakage-stopping materials is increasing. Traditional waterproof and leakage-stopping materials are mainly divided into two categories: organic and inorganic. Although organic materials (such as polyurethane and epoxy resin) have good flexibility and adhesion, they have poor weather resistance, are prone to aging, have high cost, and may release harmful volatile organic compounds (VOCs) during construction, causing environmental pollution. In contrast, inorganic waterproof and leakage-stopping materials (such as cement-based materials) have gradually become a research hotspot due to their environmental friendliness, durability and cost advantage. However, the existing inorganic waterproof and leakage-stopping materials still have many technical bottlenecks and are difficult to meet the demand for high-performance materials in modern engineering.

[0003] Traditional inorganic waterproof and leakage-stopping materials mainly use ordinary Portland cement or compound sulphoaluminate cement as the matrix, and add functional components such as expanding agent and water reducing agent to improve their impermeability and construction performance. However, these materials have the following problems in actual application: long setting time, low early strength, poor crack resistance, lack of self-healing performance, etc. In order to overcome the above problems, researchers have proposed various improvement schemes. For example: adding a coagulant, introducing a fiber reinforced material, using an expanding agent, adding a material with self-healing properties, etc. Despite the various improvement schemes, the current inorganic waterproof and leakage-stopping materials still have the following problems: the contradiction between rapid setting and self-healing performance, and insufficient healing efficiency and durability. SUMMARY

[0004] In order to make the waterproof and leakage-stopping material have the properties of rapid setting, high-efficiency self-healing and high impermeability, the application provides a self-healing and rapid-setting inorganic waterproof and leakage-stopping material and a preparation method thereof In a first aspect, the application provides a self-healing and rapid-setting inorganic waterproof and leakage-stopping material, which comprises the following raw materials by weight: 80-85 parts of sulphoaluminate cement, 4-6 parts of silica fume, 4-6 parts of mineral powder, 1-2 parts of calcium chloride, 0.5-1 part of lithium carbonate, 0.05-0.1 part of water reducing agent, 0.07-0.15 part of hydroxypropyl methylcellulose and 1-2 parts of self-healing silicon-based activator. The self-healing silicon-based activator composition comprises 0.9-1.2 parts of calcium hydroxide, 0.9-1.4 parts of magnesium fluosilicate, 0.3-0.5 parts of nano active silicon and 1.1-1.4 parts of higher fatty acid salt.

[0005] Preferably, the nano active silicon is nano silica fume.

[0006] Sulphoaluminate cement is the main component of waterproof plugging material, silica fume can fill the gap well, the plugging material is more compact, in addition, it also combines with free Ca(OH)2 to form stable calcium silicate hydrate 2CaO·SiO2·H2O, which is conducive to improving the strength of the material. The mineral powder can improve the strength and impermeability of the plugging material by improving the compactness and improving the internal structure. Calcium chloride can significantly accelerate the hydration reaction speed of cement-based materials, promote the generation of calcium silicate (C-S-H) gel, and at the same time it can provide additional calcium ions, which can react with active substances in the self-healing silica-based activator to generate more insoluble crystals and improve the impermeability; lithium ions in lithium carbonate have high reactivity, which can react with silicate minerals in cement to generate more calcium silicate (C-S-H) gel and calcium carbonate crystals. Through the addition of calcium chloride and lithium carbonate, the setting time is improved based on different effects, and more insoluble crystals are provided, which together improve the setting speed and impermeability of the waterproof plugging material under the action of the self-healing silica-based activator.

[0007] The rapid setting of the material has certain contradiction with the self-healing performance, when solving the above problems, the inventors consider selecting the components of the self-healing component, i.e. the self-healing silica-based activator. Nano active silicon can react with components such as calcium chloride in cement to improve the impermeability and strength, and the addition of high-grade fatty acid salt can shorten the setting time of the material to a certain extent without affecting the strength of the material. Calcium hydroxide can accelerate the hydration process and improve the setting speed, while the addition of a small amount of magnesium fluosilicate can prolong the setting time of the cement. The inventors found that when preparing the self-healing silica-based activator by adding calcium hydroxide, magnesium fluosilicate and nano active silicon, a better self-healing effect is unexpectedly obtained. This may be due to the fact that although calcium hydroxide can accelerate the setting, when a small amount of magnesium fluosilicate is added, its hydrolysis product can react faster with the surrounding calcium hydroxide to form insoluble crystals covering the hydration product, preventing the migration of the hydration product, thereby achieving better retarding effect. This is conducive to the active components of the self-healing silica-based activator being in a dormant state without water, and being activated in the subsequent water, and the crystallization continues to play a self-healing role, realizing the "dynamic" waterproof property of the material.

[0008] Preferably, the bulk density of the silica fume is 265 kg / m 3 , the pH value is 7, and the SiO2 content is > 90%.

[0009] Preferably, the mineral powder is S95 mineral powder, the mesh number is 600 mesh, and the density is 2.8 g / cm 3 .

[0010] Preferably, the water reducing agent is a polycarboxylic acid water reducing agent.

[0011] Preferably, the viscosity of the hydroxypropyl methyl cellulose is 100,000, and the density is 0.45 g / cm 3.

[0012] Preferably, the calcium chloride is anhydrous calcium chloride with 94% purity.

[0013] Preferably, the high-grade fatty acid salt is sodium stearate.

[0014] The polycarboxylic acid water reducing agent can reduce the water-cement ratio of the material, improve the strength and stability of the material; the viscosity of the hydroxypropyl methyl cellulose is 100,000, and the density is 0.45 g / cm 3 The selection can improve the viscosity of the inorganic waterproof plugging material, making it easier to handle and form. At the same time, it can also improve the adhesion of the material to the surface.

[0015] Preferably, the nano active silicon is amino polysiloxane modified nano silica fume.

[0016] The presence of magnesium fluosilicate and calcium hydroxide achieves the retarding effect around the nano active silicon, and when the nano active silicon is amino polysiloxane modified nano silica fume, the migration of the silicone resin can drive the active nano silicon to the surface of the plugging material, which is more conducive to its activation after encountering water, further improving the self-healing effect. On the other hand, the grafting of amino groups on the surface of nano silica fume, as well as the reaction of magnesium fluosilicate and calcium hydroxide, can make magnesium fluosilicate and calcium hydroxide achieve more effective retarding effect around the amino polysiloxane modified nano silica fume, which is conducive to the activation of the self-healing type silicon-based activator after encountering water, achieving better self-healing effect. The present application greatly improves the self-healing performance of the plugging material through the interaction of amino polysiloxane modified nano silica fume, magnesium fluosilicate and calcium hydroxide, without affecting the rapid setting of the plugging material.

[0017] Preferably, the preparation method of the amino polysiloxane modified nano silica fume comprises: surface modifying the nano silica fume with an epoxy silane coupling agent, and then adding a diamino silicone oil to obtain the amino polysiloxane modified nano silica fume.

[0018] The specific preparation method of the amino polysiloxane modified nano silica fume comprises: mixing the nano silica fume and the epoxy silane coupling agent in a 25% ethanol aqueous solution, stirring at 60-80°C for 1-3 hours, filtering, washing with deionized water for 3 times, and drying in an 80°C oven to obtain the silane modified nano silica fume; adding the silane modified nano silica fume and the diamino silicone oil into ethyl acetate, stirring at room temperature for 5 hours, and removing the solvent to obtain the amino polysiloxane modified nano silica fume.

[0019] In another aspect, the application provides a preparation method of a self-healing rapid-setting inorganic waterproof plugging material, characterized in that the method comprises the following steps: weighing each component according to the formula proportion, then adding sulphoaluminate cement into a reaction kettle first, followed by adding silica fume and mineral powder, and finally adding water reducing agent, hydroxypropyl methyl cellulose, calcium chloride, lithium carbonate and self-healing silicon-based activator in sequence, stirring at 150-350 r / min for more than half an hour, and then sealing in a bag.

[0020] Preferably, the preparation method of the self-healing silicon-based activator comprises the following steps: weighing each component according to the formula proportion, dry mixing calcium hydroxide, magnesium fluosilicate and nano active silicon for 25-35 min, and then adding senior fatty acid salt for dry mixing for 15-25 min to obtain the self-healing silicon-based activator.

[0021] The waterproof plugging material of the application is used by adding 10%-15% of water, stirring uniformly and then constructing.

[0022] In summary, the application has the following beneficial technical effects: 1. The application is based on the fact that calcium chloride can significantly accelerate the hydration reaction speed of cement-based materials, promote the generation of calcium silicate (C-S-H) gel, and at the same time, it can provide additional calcium ions which react with active substances in the self-healing silicon-based activator to generate more insoluble crystals and improve the impermeability; lithium ions in lithium carbonate have high reactivity and can react with silicate minerals in cement to generate more calcium silicate (C-S-H) gel and calcium carbonate crystals, and the addition of calcium chloride and lithium carbonate to the plugging material together improves the setting speed and impermeability of the waterproof plugging material.

[0023] 2. The application adds amino polysiloxane modified nano silica fume, magnesium fluosilicate and calcium hydroxide to achieve the retarding effect around the nano active silicon, the migration of silicone resin drives the active nano silicon to the surface of the plugging material, which is more conducive to its activation after encountering water, further improving the self-healing effect, and the reaction of the grafted amino groups on the surface of the nano silica fume with magnesium fluosilicate and calcium hydroxide enables magnesium fluosilicate and calcium hydroxide to be more preferentially distributed around the amino polysiloxane modified nano silica fume to achieve more effective retarding effect, thereby strengthening the self-healing effect of the self-healing silicon-based activator. The application greatly improves the self-healing performance of the plugging material through the interaction of the amino polysiloxane modified nano silica fume, magnesium fluosilicate and calcium hydroxide without affecting the rapid setting of the plugging material.

[0024] 3、The waterproof plugging material of the application realizes the synergistic improvement of rapid solidification, high-efficiency self-healing and high impermeability by optimizing the ratio of the base material and the functional component, combining the nano-modification technology and the crystalline self-healing agent. Specifically, the application uses single sulphoaluminate cement as the base material, realizes rapid solidification by introducing lithium carbonate, calcium chloride and other materials; at the same time, the self-healing type silicon-based activator triggers a secondary hydration reaction when it meets water, generating C-S-H gel and ettringite crystals, thereby sealing microcracks and realizing the self-healing function of the material. In addition, the addition of the self-healing type silicon-based activator further improves the density and impermeability of the material, so that it can still maintain excellent waterproof effect in high water pressure environment.

[0025] 4、The application of the scheme not only solves the problems of long solidification time and low early strength of traditional inorganic waterproof plugging materials, but also endows the material with self-healing performance by introducing the self-healing crystallization technology, thereby improving the durability of the material. The material has multiple advantages such as rapid solidification, self-healing, high impermeability, environmental protection, etc., and can be widely applied in waterproof plugging construction in the fields of building, tunnel, underground engineering, etc., and has important engineering application value and market prospect. DETAILED DESCRIPTION

[0026] The application is further described below through examples.

[0027] Sulphoaluminate cement was purchased from Anjianhongye; the bulk density of silica fume: 265 kg / m 3 , pH value: 7, SiO2content > 90%; mineral powder is S95 mineral powder, mesh 600, density 2.8 g / cm 3 ; calcium chloride is 94% pure anhydrous calcium chloride; lithium carbonate is industrial grade, density 2.11 g / m 3 ; water reducing agent is LG-2, purchased from Boerda Building Materials; hydroxypropyl methylcellulose viscosity is 100,000, density is 0.45 g / cm 3 ; nano-silica fume: SiO2content 92%-96%, purchased from Haire Refractory Materials; diamino silicone oil CM-226. Other components are conventional grades in the art or obtained by conventional processes. EXAMPLE

[0028] Example 1: Preparation method of self-healing type silicon-based activator: weigh each component according to the formulation ratio in Table I, dry mix calcium hydroxide, magnesium fluosilicate and nano-silica fume for 30 min, then add sodium stearate and dry mix for 20 min to obtain the product; Preparation method of waterproof plugging material: weigh each component according to the proportion of table one, then add sulphoaluminate cement first, then add silica fume and mineral powder, finally add water reducing agent, hydroxypropyl methyl cellulose, calcium chloride, lithium carbonate and self-healing silicon-based activator in turn, stir for more than half an hour at 200 r / min, then seal in bags.

[0029] Examples 2-4: The difference between examples 2-4 and example 1 is only the difference in component proportion, see table one for the proportion.

[0030] Table one According to GB 23440-2009 Inorganic Waterproof Plugging Material, test pieces are prepared according to the proportions and methods of examples 1-4. The standard requires initial setting, final setting, 1h / 3d flexural and compressive strength, 7d bonding strength and 7d test piece impermeable pressure of rapid setting type inorganic waterproof plugging material. The specific test results are shown in table two.

[0031] Table two As can be seen from the above table: the flexural strength, compressive strength, impermeable strength and bonding strength of examples 1-4 of the present application far exceed the specification requirements, and can achieve the effect of rapid setting.

[0032] According to T / CECS 913-2021 Test method for self-healing performance of cement concrete, the load damage compressive strength recovery rate of examples 1-4 is tested, and the test results are shown in table three.

[0033] Table three As can be seen from the above table: examples 1-4 of the present application have good load damage recovery capacity, which shows that the present application has good self-healing ability.

[0034] Example 5 The difference between Example 5 and Example 4 is only that the nano-silica is amino polysiloxane modified nano-silica. The specific preparation method of the amino polysiloxane modified nano-silica comprises: 20 g of nano-silica and 2 g of epoxy silane coupling agent KH560 are added into 300 mL of 25% concentration ethanol aqueous solution for mixing, stirring at 70°C for 2 hours, filtering, washing with deionized water for 3 times, drying in an oven at 80°C, to obtain silane modified nano-silica; the silane modified nano-silica and 8 g of diamino silicone oil are added into 250 mL of ethyl acetate, stirring at room temperature for 5 hours, removing the solvent, to obtain amino polysiloxane modified nano-silica.

[0035] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is only that the calcium chloride is replaced by an equal amount of lithium carbonate.

[0036] Comparative Example 2 The difference between Comparative Example 1 and Example 1 is only that the calcium chloride is replaced by an equal amount of lithium carbonate.

[0037] Comparative Example 3 The difference between Comparative Example 1 and Example 5 is only that the magnesium fluosilicate is replaced by an equal amount of calcium hydroxide when preparing the self-healing type silicon-based activator.

[0038] Comparative Example 4 The difference between Comparative Example 4 and Example 5 is only that the calcium hydroxide is replaced by an equal amount of magnesium fluosilicate when preparing the self-healing type silicon-based activator.

[0039] According to GB 23440-2009 Inorganic Waterproof Plugging Material, the test pieces are prepared according to the proportions and methods of Example 5 and Comparative Examples 1-4. The standard has requirements for the initial setting, final setting, 1h / 3d flexural and compressive strength, 7d bonding strength and 7d test piece impermeable pressure of the rapid setting type inorganic waterproof plugging material. The specific test results are shown in Table Four.

[0040] Table Four As can be seen from the above table, the flexural strength, compressive strength, impermeable strength and bonding strength of Example 5 are similar to or better than those of Example 4, indicating that the modified active silicon does not adversely affect the comprehensive performance of the plugging material. Compared with Comparative Examples 1-2, the initial setting and final setting of Example 1 are faster, and the flexural strength, compressive strength, impermeable strength and bonding strength are all better, which indicates that the joint addition of calcium chloride and lithium carbonate reduces the setting time and optimizes the comprehensive performance. Compared with Comparative Examples 3-4, the setting parameters of Example 5 change little, and the flexural strength, compressive strength, impermeable strength and bonding strength can also reach similar or better levels.

[0041] According to T / CECS 913-2021 "Standard for Test Methods of Self-Healing Performance of Cement Concrete", the load damage compressive strength recovery rates of Examples 4-5 and 3-4 are tested, and the test results are shown in Table 5.

[0042] Table 5 As can be seen from the above table, Example 5 of the present application has good load damage recovery ability compared with Example 4, and the self-healing performance of Comparative Example 3 or Comparative Example 4 is reduced when the self-healing type silicon-based activator lacks calcium hydroxide or magnesium fluorosilicate, indicating that the self-healing ability of the plugging material is improved by the combined action of the amino polysiloxane modified nano-silica, calcium hydroxide and magnesium fluorosilicate.

[0043] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application, and those skilled in the art can make non-creative modifications to the embodiments according to the needs after reading the specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A self-healing and rapid setting inorganic waterproof plugging material, characterized in that, The self-healing type silicon-based activator is prepared by the following steps: weighing each component according to the formula proportion, dry mixing calcium hydroxide, magnesium fluosilicate and nano active silicon for 25-35 min, and then adding a higher fatty acid salt and dry mixing for 15-25 min. The self-healing type silicon-based activator is prepared by the following steps: weighing each component according to the formula proportion, dry mixing calcium hydroxide, magnesium fluosilicate and nano active silicon for 25-35 min, and then adding a higher fatty acid salt and dry mixing for 15-25 min.

2. The self-healing rapid setting inorganic waterproof plugging material according to claim 1, characterized in that, The bulk density of the silica fume is 265 kg / m 3 pH 7, SiO2 content > 90%.

3. The self-healing rapid setting inorganic waterproof plugging material according to claim 1, characterized in that, The mineral powder is S95 mineral powder with a mesh number of 600 and a density of 2.8 g / cm³.

4. The self-healing rapid setting inorganic waterproof plugging material according to claim 1, characterized in that, The water reducing agent is a polycarboxylic acid water reducing agent, the hydroxypropyl methyl cellulose has a viscosity of 100,000 and a density of 0.45 g / cm 3 .

5. The self-healing rapid setting inorganic waterproof plugging material according to claim 1, characterized in that, The calcium chloride is anhydrous calcium chloride with a purity of 94%.

6. The self-healing rapid setting inorganic waterproof plugging material according to claim 1, characterized in that, The higher fatty acid salt is sodium stearate.

7. The self-healing rapid setting inorganic waterproof plugging material according to claim 1, characterized in that, The nano active silicon is amino polysiloxane modified nano silica.

8. The self-healing rapid setting inorganic waterproof plugging material according to claim 7, characterized in that, The preparation method of the amino polysiloxane modified nano silica includes the following steps: surface modification of nano silica by an epoxy silane coupling agent, and then adding a diamino silicone oil to obtain amino polysiloxane modified nano silica.

9. A method for preparing the self-healing rapid setting inorganic waterproof plugging material according to any one of claims 1-8, characterized in that, The preparation method of the self-healing type silicon-based activator includes the following steps: weighing each component according to the formula proportion, dry mixing calcium hydroxide, magnesium fluosilicate and nano active silicon for 25-35 min, and then adding a higher fatty acid salt and dry mixing for 15-25 min.

10. The method for preparing the self-healing rapid setting inorganic waterproof plugging material according to claim 9, characterized in that, The preparation method of the self-healing type silicon-based activator includes the following steps: weighing each component according to the formula proportion, dry mixing calcium hydroxide, magnesium fluosilicate and nano active silicon for 25-35 min, and then adding a higher fatty acid salt and dry mixing for 15-25 min.

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