3D printing tunnel spray waterproof material

Abstract

The present application belongs to the technical field of building materials, and particularly relates to a 3D printing tunnel spraying waterproof material. The 3D printing tunnel spraying waterproof material comprises mortar and a water-repellent agent. The water-repellent agent is prepared by the following steps: (1) adding isobutyl triethoxysilane and hydroxyl polydimethylsiloxane into modified silica sol and mixing uniformly; (2) adding polyacrylic acid, mixing uniformly, and freeze-drying to obtain the water-repellent agent. The modified silica sol is silane coupling agent modified silica sol. The 3D printing tunnel spraying waterproof material has good water-repellent performance and bonding performance.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a 3D printed tunnel spray waterproof material. Background Technology

[0002] 3D-printed building materials are commonly used in tunnel construction. During tunnel construction or use, water seepage can occur, threatening the safety and lifespan of the tunnel. This necessitates materials used in tunnel construction with excellent waterproof properties.

[0003] In existing technologies, waterproofing performance is generally improved by adding water-repellent agents; however, water-repellent agents may weaken the bond between mortar and substrate; in addition, if the water-repellent agent has poor compatibility with the mortar, it will also affect the density of the mortar, thereby causing a decrease in mechanical properties.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a 3D printed tunnel spray waterproof material to help solve or improve the problem of reduced bonding strength and / or mechanical properties caused by adding water-repellent agents to mortar in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a 3D printed tunnel spray waterproof material, wherein the components of the 3D printed tunnel spray waterproof material include mortar and a water-repellent agent; the water-repellent agent is prepared by a method including the following steps: (1) adding isobutyltriethoxysilane and hydroxyl polydimethylsiloxane to modified silica sol and mixing them evenly; (2) adding polyacrylic acid, mixing them evenly, and freeze-drying to obtain the water-repellent agent; the modified silica sol is a silane coupling agent modified silica sol.

[0007] Preferably, in step (1), the mass ratio of isobutyltriethoxysilane to modified silica sol is (2.8-3.2):1, and the mass ratio of hydroxyl polydimethylsiloxane to isobutyltriethoxysilane is (0.005-0.008):1.

[0008] Preferably, in step (2), the mass ratio of polyacrylic acid to isobutyltriethoxysilane is (0.01-0.015):1.

[0009] Preferably, the modified silica sol is prepared by a method comprising the following steps: adding a silane coupling agent solution dropwise to the silica sol and stirring at 20-30°C for 1.5-2 hours to obtain the modified silica sol.

[0010] Preferably, the silica sol has a pH of 7-8 and a solid content of 25wt%-30wt%.

[0011] Preferably, the solvent in the silane coupling agent solution is anhydrous ethanol, and the mass ratio of anhydrous ethanol to silane coupling agent is (0.3-0.5):(0.2-0.35); the mass ratio of silica sol to silane coupling agent in the silane coupling agent solution is 10:(0.2-0.35).

[0012] Preferably, the mortar comprises cementitious materials, aggregates, quick-setting agents, early-strength agents, and water.

[0013] Preferably, the cementitious material comprises ordinary silicate cement and fly ash; the aggregate comprises coarse aggregate and fine aggregate, wherein the fineness modulus of the fine aggregate is 2.8-3.2; the mass ratio of water to cementitious material is 0.3-0.4; and the mass of the water-repellent agent is 0.1%-0.2% of the sum of the mass of the solid components in the mortar.

[0014] Beneficial effects: In the 3D-printed tunnel spray-applied waterproof material of this invention, when mortar is mixed with water, the protective colloidal shell of the water-repellent agent rapidly dissolves in the water, releasing the encapsulated silane, which is then redispersed in the mixing water. Under the highly alkaline environment after cement hydration, the hydrophilic organic functional groups in the silane hydrolyze to form highly reactive silanol groups. These silanol groups continue to undergo irreversible reactions with the hydroxyl groups in the cement hydration products, forming chemical bonds. This allows the silane, linked together through cross-linking, to be firmly fixed to the pore wall surface in the cement mortar. Because the hydrophobic organic functional groups face outwards from the pore wall, the surface of the pores acquires hydrophobicity, thereby providing the mortar with an overall hydrophobic effect.

[0015] In addition, the 3D printed tunnel spray waterproof material of the present invention has good adhesion properties; the water-repellent agent has good compatibility with mortar and will not adversely affect the mechanical properties of mortar. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 The figures show the hydrophobicity test results of Examples 1-2 and Comparative Example 1. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0018] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0019] This invention addresses the problem of decreased bonding strength and / or mechanical properties caused by adding water-repellent agents to mortar in existing technologies, and provides a 3D-printed tunnel spray-applied waterproof material.

[0020] The 3D-printed tunnel spray-applied waterproof material of the present invention will be described in detail below through specific embodiments.

[0021] The components of the 3D printed tunnel spray waterproof material of this invention include mortar and a water-repellent agent; the water-repellent agent is prepared by a method including the following steps: (1) adding isobutyltriethoxysilane and hydroxyl polydimethylsiloxane to the modified silica sol and mixing them evenly; (2) adding polyacrylic acid, mixing them evenly, and freeze-drying to obtain the water-repellent agent; the modified silica sol is a silane coupling agent modified silica sol.

[0022] In the water-repellent agent of the 3D-printed tunnel spray waterproofing material of this invention, the introduction of silane coupling agent-modified silica sol not only helps improve the compatibility of isobutyltriethoxysilane with mortar materials, but the silica contained in the silica sol also helps improve the density of the mortar. Hydroxyl polydimethylsiloxane has terminal hydroxyl groups, which interact with polyacrylic acid through hydrogen bonds during the preparation of the water-repellent agent, helping to promote the encapsulation of isobutyltriethoxysilane by the polyacrylic acid. The introduction of polyacrylic acid allows the polyacrylic acid encapsulated on the surface of isobutyltriethoxysilane to dissolve rapidly in water after the water-repellent agent is added to the mortar, releasing the encapsulated isobutyltriethoxysilane. Furthermore, in the highly alkaline environment of mortar (containing cement) hydration, the hydrophilic organic functional groups in the silane hydrolyze to form highly reactive silanol groups. The silanol groups continue to undergo irreversible reactions with the hydroxyl groups in the cement hydration products to form chemical bonds, thereby firmly fixing the silanes linked together through cross-linking to the pore wall surface in the cement mortar. Because the hydrophobic organic functional groups face outwards from the pore wall, the surface of the pores becomes hydrophobic, thus giving the mortar an overall hydrophobic effect.

[0023] The 3D printed tunnel spray waterproof material of the present invention has good adhesion properties; the water-repellent agent has good compatibility with mortar and will not adversely affect the mechanical properties of mortar.

[0024] In a preferred embodiment of the 3D printed tunnel spray waterproof material of the present invention, in step (1), the mass ratio of isobutyltriethoxysilane to modified silica sol is (2.8-3.2):1 (e.g., 2.8:1, 2.9:1, 3:1, 3.1:1 or 3.2:1), and the mass ratio of hydroxyl polydimethylsiloxane to isobutyltriethoxysilane is (0.005-0.008):1 (e.g., 0.005:1, 0.006:1, 0.007:1 or 0.008:1).

[0025] In a preferred embodiment of the 3D printed tunnel spray waterproof material of the present invention, in step (2), the mass ratio of polyacrylic acid to isobutyltriethoxysilane is (0.01-0.015):1 (for example, 0.01:1, 0.011:1, 0.012:1, 0.013:1, 0.014:1 or 0.015:1).

[0026] In a preferred embodiment of the 3D-printed tunnel spray-applied waterproof material of the present invention, the modified silica sol is prepared by a method comprising the following steps: adding a silane coupling agent solution dropwise to the silica sol and stirring at 20-30°C (e.g., 20°C, 23°C, 26°C, 28°C or 30°C) for 1.5-2 hours (e.g., 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours) to obtain the modified silica sol.

[0027] In a preferred embodiment of the 3D-printed tunnel spray waterproof material of the present invention, the pH of the silica sol is 7-8 (e.g., 7, 7.5 or 8), and the solid content of the silica sol is 25wt%-30wt% (e.g., 25wt%, 26wt%, 27wt%, 28wt%, 29wt% or 30wt%).

[0028] In a preferred embodiment of the 3D-printed tunnel spray-applied waterproof material of the present invention, the solvent in the silane coupling agent solution is anhydrous ethanol, and the mass ratio of anhydrous ethanol to silane coupling agent is (0.3-0.5):(0.2-0.35) (e.g., 0.3:0.2, 0.3:0.3, 0.3:0.35, 0.5:0.2, 0.5:0.25, 0.5:0.35, 0.4:0.2, 0.4:0.28, or 0.4:0.35); the mass ratio of silica sol to silane coupling agent in the silane coupling agent solution is 10:(0.2-0.35) (e.g., 10:0.2, 10:0.25, 10:0.3, or 10:0.35).

[0029] In a preferred embodiment of the 3D-printed tunnel spray-applied waterproof material of the present invention, the mortar components include cementitious materials, aggregates, quick-setting agents, early-strength agents, and water.

[0030] In a preferred embodiment of the 3D-printed tunnel spray-applied waterproof material of the present invention, the cementitious material comprises ordinary silicate cement and fly ash; the aggregate comprises coarse aggregate and fine aggregate, wherein the coarse aggregate has a sieve residue rate of 88%-96% on a 0.15mm square hole sieve and a sieve residue rate of 0-10% on a 9.5mm square hole sieve; the fineness modulus of the fine aggregate is 2.8-3.2; the mass ratio of water to cementitious material is 0.3-0.4 (e.g., 0.3, 0.32, 0.34, 0.36, 0.38 or 0.4); and the mass of the water-repellent agent is 0.1%-0.2% of the sum of the mass of the solid components in the mortar (e.g., 0.1%, 0.12%, 0.14%, 0.16%, 0.18% or 0.2%).

[0031] Preferably, the mortar also includes steel fibers.

[0032] Preferably, the dosage of the early-strength agent is 5%-10% of the mass of the cementitious material; the dosage of the quick-setting agent is 5%-8% of the mass of the cementitious material; the dosage of fine aggregate (manufactured sand) is 1.5-1.6 times the mass of the cementitious material; the dosage of coarse aggregate (gravel) is 1.25-1.35 times the mass of the cementitious material; the dosage of water-reducing agent is 1.5%-2% of the mass of the cementitious material; the dosage of steel fiber is 1.5%-1.6% of the mass of the cementitious material; and the mass ratio of cement to fly ash is (10-11):1.

[0033] Unless otherwise specified, all raw materials used in the following examples are commercially available; among them: the cement used is P.O42.5 ordinary Portland cement; the fly ash used is Class II F fly ash (meeting the requirements of GB / T1596-2017 "Fly Ash for Cement and Concrete"); the accelerator is UEA accelerator from Wuhan Jiyesheng Chemical Co., Ltd.; the accelerator is liquid alkali-free accelerator (SL15 high-strength liquid alkali-free accelerator from Suolaite New Materials Co., Ltd.); the steel fiber is 0.55×25 type cold-drawn end-hook steel fiber (tensile strength ≥1100MPa, aspect ratio 45.4); the fineness modulus of the fine aggregate is 2.8-3.2, which meets the requirements of the current "Standard for Quality and Test Methods of Sand and Stone for Ordinary Concrete" JGJ52; the coarse aggregate is 0.5-1.0cm stone aggregate, which meets the requirements shown in Table 1 below: Table 1

[0034] Example 1 The components of the 3D printed tunnel spray waterproof material of the present invention include: mortar and water-repellent agent (the mass of the water-repellent agent is 0.1% of the total mass of the solid components in the mortar; the fineness of the water-repellent agent is: ≤10% residue on a 150μm sieve). The water-repellent agent was prepared by the following steps: (1) Add 3 parts by mass of isobutyltriethoxysilane and 0.006 parts by mass of hydroxyl polydimethylsiloxane (average molecular weight 2500) to 1 part by mass of modified silica sol, sonicate for 30 min, then heat to 65°C and stir (300 r / min) for 1 h to mix evenly; (2) Add 0.036 parts by weight of polyacrylic acid (average molecular weight 5000), mix evenly (stir at 65℃ for 1.5h, stirring speed 300r / min), freeze dry (-20℃, 10Pa) to obtain the water-repellent agent.

[0035] The modified silica sol was prepared by the following steps: a silane coupling agent solution (silane coupling agent is KH560, solvent is anhydrous ethanol; the amount of silane coupling agent is 0.2 parts by mass, and the amount of anhydrous ethanol is 0.4 parts by mass) was added dropwise to 10 parts by mass of silica sol (pH=7.5, solid content is 25wt%), and the mixture was stirred at 30℃ for 1.8h to obtain the modified silica sol.

[0036] The mortar, by weight, comprises: 105 parts cement, 10 parts fly ash, 10 parts early-strength agent, 7 parts quick-setting agent, 175 parts fine aggregate, 145 parts coarse aggregate, 38 parts water, 5 parts steel fiber, and 1.5 parts water-reducing agent. The mortar is prepared and used immediately. During 3D printing, the cement, fly ash, early-strength agent, fine aggregate, coarse aggregate, steel fiber, water-reducing agent, and water-repellent agent are mixed evenly, and then water is added to mix, resulting in a premix. During 3D printing, the premix is ​​mixed with the quick-setting agent (liquid alkali-free quick-setting agent) at the nozzle.

[0037] Example 2 The only difference between the 3D printed tunnel spray waterproof material in this embodiment and that in Embodiment 1 is that the mass of the water-repellent agent is 0.2% of the mass of the mortar (the sum of the masses of the solid components in the mortar); all other aspects are consistent with Embodiment 1.

[0038] Comparative Example 1 The only difference between this comparative example and Example 1 is that the mass of the hydrophobic agent is 0; all other aspects are the same as in Example 1.

[0039] Comparative Example 2 The only difference between this comparative example and Example 1 is that, in the preparation of the hydrophobic agent (step (1)), silica sol is used instead of modified silica sol (i.e., the silica sol is not modified by silane coupling agent); otherwise, it is consistent with Example 1.

[0040] Comparative Example 3 The only difference between this comparative example and Example 1 is that the step of adding modified silica sol is omitted in the preparation of the hydrophobic agent (step (1)); the rest are consistent with Example 1.

[0041] Comparative Example 4 The only difference between this comparative example and Example 1 is that the step of adding hydroxyl polydimethylsiloxane is omitted in the preparation of the hydrophobic agent (step (1)), and the amount of polyacrylic acid is increased to 0.042 parts by mass; the rest are consistent with Example 1.

[0042] Experimental Example 1. Hydrophobicity test: Referring to the test method for hydrophobicity of materials in GB / T 45017-2024 "Mechanical Stability Test Method for Superhydrophobic Surfaces", the contact angle of the 3D printed tunnel spray waterproof material was tested.

[0043] The test results are shown in Table 2 below: Table 2

[0044] The contact angle test diagrams for Examples 1-2 and Comparative Example 1 are shown below. Figure 1 As shown in Figure 1, it can be seen that the hydrophobic agent can effectively improve the hydrophobicity of the 3D printed tunnel spray waterproof material.

[0045] 2. Water absorption test: The water absorption of the materials was tested in accordance with the "Code for Waterproofing Design of Underground Engineering" GB 50108-2008.

[0046] The test results of the 3D printed tunnel spray waterproof material in Example 1 are shown in the table below.

[0047] Table 3

[0048] The results showed that after immersion in water for 72 hours, the water absorption rate was 2.2% (less than 3%), which met the specifications.

[0049] 3. Adhesion and 28-day compressive strength tests: The test results are shown in the table below: Table 4

[0050] As shown in the table above, the 3D printed tunnel spray waterproof material of the present invention has excellent adhesion and mechanical properties.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A 3D-printed tunnel spray-applied waterproof material, characterized in that, The components of the 3D printed tunnel spray waterproof material include mortar and a water-repellent agent; The hydrophobic agent is prepared by a method comprising the following steps: (1) Add isobutyltriethoxysilane and hydroxyl polydimethylsiloxane to the modified silica sol and mix well; (2) Add polyacrylic acid, mix well, and freeze dry to obtain the water-repellent agent; The modified silica sol is a silane coupling agent modified silica sol.

2. The 3D-printed tunnel spray-applied waterproof material as described in claim 1, characterized in that, In step (1), the mass ratio of isobutyltriethoxysilane to modified silica sol is (2.8-3.2):1, and the mass ratio of hydroxyl polydimethylsiloxane to isobutyltriethoxysilane is (0.005-0.008):

1.

3. The 3D-printed tunnel spray-applied waterproof material as described in claim 1, characterized in that, In step (2), the mass ratio of polyacrylic acid to isobutyltriethoxysilane is (0.01-0.015):

1.

4. The 3D-printed tunnel spray-applied waterproof material as described in claim 1, characterized in that, The modified silica sol is prepared by a method including the following steps: adding a silane coupling agent solution dropwise to the silica sol and stirring at 20-30°C for 1.5-2 hours to obtain the modified silica sol.

5. The 3D-printed tunnel spray-applied waterproof material as described in claim 4, characterized in that, The silica sol has a pH of 7-8 and a solid content of 25wt%-30wt%.

6. The 3D-printed tunnel spray-applied waterproof material as described in claim 5, characterized in that, The solvent in the silane coupling agent solution is anhydrous ethanol, and the mass ratio of anhydrous ethanol to silane coupling agent is (0.3-0.5):(0.2-0.35). The mass ratio of the silica sol to the silane coupling agent in the silane coupling agent solution is 10:(0.2-0.35).

7. The 3D-printed tunnel spray-applied waterproof material as described in claim 1, characterized in that, The mortar consists of cementitious materials, aggregates, quick-setting agents, early-strength agents, and water.

8. The 3D-printed tunnel spray-applied waterproof material as described in claim 7, characterized in that, The cementitious material comprises ordinary silicate cement and fly ash; The aggregate includes coarse aggregate and fine aggregate, wherein the fineness modulus of the fine aggregate is 2.8-3.2; The mass ratio of water to cementitious material is 0.3-0.4; The mass of the water-repellent agent is 0.1%-0.2% of the sum of the masses of the solid components in the mortar.

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