Hydrophobic cement-based material and preparation method thereof

Abstract

The invention provides a hydrophobic cement-based material and a preparation method thereof.The hydrophobic cement-based material is prepared from, by mass, 40%-60% of cement, 1%-5% of silica fume, 30%-60% of quartz sand, 0.1%-0.5% of cellulose ether, 0.1%-0.5% of a water reducing agent, 0.1%-0.5% of a defoaming agent, 0.1%-0.5% of a hydrophobic agent, 0.4%-1.6% of nano-silica and 0.1%-1% of a wetting dispersant. Wherein the water repellent agent is organic silicon powder. According to the invention, the organosilicon powder with slow release property is directly added as the water repellent agent, so that common and tedious water repellent agent preparation and addition processes are effectively avoided; by adding the nano silicon dioxide, the hydrophobicity is further provided, the defect that the mechanical property is reduced due to the addition of the hydrophobic agent is overcome, the preparation process is simple, and the production cost of the hydrophobic cement-based material can be remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and more specifically, to a hydrophobic cement-based material and a preparation method thereof. Background Art

[0002] Cement-based materials are widely used in construction and many engineering fields, but they also face many practical problems. On the one hand, the intrusion of water can easily lead to freeze-thaw damage to cement-based materials. In a low-temperature environment, the water in the pores freezes and expands, generating internal stress, which damages the material structure and reduces its durability. On the other hand, long-term exposure to a humid environment will accelerate the corrosion of internal reinforcement materials such as steel bars, affecting the mechanical properties and safety of the overall structure. Moreover, moisture adsorption may also breed microorganisms, affecting the appearance and use function. Therefore, hydrophobic modification can effectively improve the waterproof and moisture-proof ability, frost resistance and chloride ion corrosion resistance of cement-based materials, thereby extending their service life and ensuring their performance.

[0003] The hydrophobic modification technology of cement-based materials is mainly divided into two methods: surface modification and overall modification. Surface modification enhances durability by attaching hydrophobic materials to the surface of cement-based materials to form a protective layer. The surface hydrophobic coating is easily destroyed or degraded by environmental factors (such as ultraviolet rays, temperature changes, and mechanical wear). Overall modification is to add hydrophobic additives during the mixing process to make the entire material hydrophobic, which has greater advantages in practical applications. However, overall hydrophobic modification technology usually affects the mechanical properties of the material, and is prone to uneven dispersion inside the material, affecting the modification effect.

[0004] The overall hydrophobic modification technology of cement-based materials is mainly achieved by directly adding hydrophobic materials during the preparation process of concrete. These hydrophobic materials include low surface energy substances such as silane, siloxane, stearic acid, and hydrophobically modified cementitious materials or powder materials. The overall hydrophobic modification can make the concrete both inside and on the surface hydrophobic, thereby improving the durability and impermeability of the concrete. For example, Chinese patent application CN118184197B discloses a preparation method of a hydrophobic enhancer and its high impermeability cement-based materials and applications. The hydrophobic enhancer can not reduce the strength of the cement-based materials while giving the cement-based materials long-term hydrophobicity, but the solution has a complex preparation process of the hydrophobic agent, a large difficulty in controlling the multi-step reaction, and it is difficult to ensure the stability of product performance. Chinese patent application CN118184267B discloses a preparation method of a super-hydrophobic high-strength cement-based material and its application. The published preparation process can prevent the hydrophobic agent from contacting the cement particles early, and the mechanical properties will not deteriorate while realizing the overall hydrophobic modification of the cement-based material. However, the preparation steps of this scheme are too complicated, including ultrasonic dispersion, pH adjustment, heating and stirring reaction, multiple washing, drying, emulsification and other steps. Each step requires specific conditions and equipment, such as ultrasonic equipment, heating equipment, high-speed shearing machine, etc., which makes the preparation process complicated and time-consuming, and the actual production cost is high.

[0005] Therefore, a better solution for hydrophobicity of cement-based materials is urgently needed. Summary of the invention

[0006] In view of the above problems, an object of the present invention is to provide a hydrophobic cement-based material and a preparation method thereof to solve at least one of the above technical problems.

[0007] According to one aspect of the present invention, a hydrophobic cement-based material is provided, comprising the following raw materials in percentage by weight: 40% to 60% cement, 1% to 5% silica fume, 30% to 60% quartz sand, 0.1% to 0.5% cellulose ether, 0.1% to 0.5% water reducer, 0.1% to 0.5% defoamer, 0.1% to 0.5% hydrophobic agent, 0.4% to 1.6% nano silicon dioxide, and 0.1% to 1% wetting dispersant;

[0008] Wherein, the hydrophobic agent is organic silicon powder.

[0009] Furthermore, preferably, the cement is ordinary Portland cement.

[0010] Furthermore, preferably, the cellulose ether is methyl hydroxypropyl cellulose ether, and the viscosity is less than 10000 mPa·s.

[0011] Furthermore, preferably, the water reducing agent is a polycarboxylic acid-based high-performance water reducing agent.

[0012] Furthermore, preferably, the defoaming agent is polyethylene glycol vegetable oil.

[0013] Furthermore, preferably, the average diameter of the organosilicon powder is 300 μm and the volume density is 600 g / l.

[0014] Further, preferably, the average diameter of the nano-silicon dioxide is 30nm and the specific surface area is 120m 2 / g.

[0015] Furthermore, preferably, the dispersant is a non-ionic modified fat derivative and a polyethylene glycol ester.

[0016] The present invention also protects a method for preparing a hydrophobic cement-based material, which is used to prepare the above-mentioned hydrophobic cement-based material; the method comprises:

[0017] 0.1% to 0.5% by weight of cellulose ether, 0.1% to 0.5% by weight of water reducing agent, 0.1% to 0.5% by weight of defoaming agent, 0.1% to 0.5% by weight of hydrophobic agent, 0.4% to 1.6% by weight of nano silicon dioxide and 0.1% to 1% by weight of wetting and dispersing agent are weighed and put into a high-speed dispersing mixer, and dispersed for a first preset time to obtain a premixed small material;

[0018] 40% to 60% by weight of cement, 1% to 5% of silica fume, 30% to 60% of quartz sand and the premixed small materials are put into a zero-gravity mixer and dispersed for a second preset time to obtain a hydrophobic cement-based material.

[0019] Further, preferably, the first preset time is 15 minutes to 20 minutes, and the second preset time is 3 minutes to 5 minutes.

[0020] The hydrophobic cement-based material and preparation method thereof according to the present invention, by directly adding a sustained-release organosilicon powder as a hydrophobic agent, effectively avoids the common cumbersome preparation and addition process of the hydrophobic agent; by adding nano-silicon dioxide, hydrophobicity is further provided, and the cement-based material has a reinforcing effect, which makes up for the decrease in mechanical properties caused by the addition of the hydrophobic agent; and by adding a wetting dispersant, the uniformity of the hydrophobic agent dispersion is ensured, overcoming the decrease in mechanical properties caused by uneven dispersion. The preparation process of the present invention is simple, and the production cost of the hydrophobic cement-based material can be significantly reduced.

[0021] In order to achieve the above and related purposes, one or more aspects of the present invention include features that will be described in detail later and are particularly pointed out in the claims. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all of these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] By referring to the following description and claims in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the accompanying drawings:

[0023] Figure 1 A flow chart showing a method for preparing a hydrophobic cement-based material according to the present invention is shown.

[0024] The same reference numerals throughout the drawings indicate similar or corresponding features or functions. DETAILED DESCRIPTION

[0025] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is apparent that these embodiments may also be implemented without these specific details. In other examples, for ease of describing one or more embodiments, known structures and devices are shown in the form of block diagrams.

[0026] The existing overall hydrophobic modification technology, because it is necessary to add a hydrophobic agent to cement, may affect the hydration process of cement, therefore, there is a certain influence on the formed cement structure, which will affect the mechanical properties of concrete, such as strength and toughness. In addition, some hydrophobic agents are decomposed, worn or lost under the influence of environmental factors during long-term use, or because the pore structure inside the cement-based material changes, so that the effect of the hydrophobic agent is weakened, the hydrophobicity will gradually decrease, resulting in a decrease in the waterproof performance of the cement-based material. In addition, the cost of the hydrophobic agent is relatively high, which also limits its wide application in large-scale projects. In addition, the overall hydrophobic modification needs to be carried out during the stirring and curing process, and the steps are many and cumbersome, which increases the complexity of production and construction, and is easily dispersed unevenly inside the material, which also affects the modification effect.

[0027] Based on the above problems, the present invention compared and analyzed the working performance and basic mechanical properties of mortars in various working conditions under different raw material dosages, and conducted a comparative analysis on the contact angle test of water inside the mortar, and obtained a hydrophobic cement-based material with greatly improved working performance and mechanical properties.

[0028] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] The hydrophobic cement-based material of the present invention comprises the following raw materials in percentage by weight:

[0030] Cement 40%-60%, silica fume 1%-5%, quartz sand 30%-60%, cellulose ether 0.1%-0.5%, water reducing agent 0.1%-0.5%, defoaming agent 0.1%-0.5%, hydrophobic agent 0.1%-0.5%, nano silicon dioxide 0.4%-1.6%, wetting dispersant 0.1%-1%; the hydrophobic agent is organic silicon powder.

[0031] Silicone powder (such as Dow Corning SHP50, Longchen S90) uses high-tech carriers and slow-release technology to enable the active substances to be released in time after encountering water, and has excellent hydrophobic effect after the substrate is cured. It can be directly added to the dry mix of cement-based materials to prevent the capillaries / pores in the material from absorbing water, and provide the overall hydrophobic performance of the cement-based material after curing. Therefore, in the present invention, silicone powder is directly added as a hydrophobic agent.

[0032] In addition, the present invention also utilizes the characteristics of nano materials to prepare hydrophobic cement-based materials by compounding an organic silicon powder hydrophobic agent with nano silicon dioxide.

[0033] Nano-silica can significantly improve the surface hydrophobicity of cement-based materials by forming a micro-nano rough structure. Therefore, the combination of organosilicon powder hydrophobic agent and nano-silica can effectively improve the durability of the hydrophobic effect. In addition, the addition of nano-silica can also promote cement hydration and hardening through the nucleation effect and volcanic ash activity, reducing the impact of hydrophobic modification on mechanical properties.

[0034] In addition, in a specific embodiment of the present invention, the cement is ordinary Portland cement, more specifically, ordinary Portland cement P·O 52.5 can be selected.

[0035] In a specific embodiment of the present invention, the silica fume is semi-densified silica fume.

[0036] In a specific embodiment of the present invention, the cellulose ether is methyl hydroxypropyl cellulose ether, and the viscosity is less than 10000 mPa·s.

[0037] In a specific embodiment of the present invention, the water reducing agent is a polycarboxylic acid-based high-performance water reducing agent.

[0038] In a specific embodiment of the present invention, the defoaming agent is polyethylene glycol vegetable oil.

[0039] In a specific embodiment of the present invention, the average diameter of the organic silicon powder used as the hydrophobic agent is 300 μm, and the volume density is 600 g / l.

[0040] In a specific embodiment of the present invention, the average diameter of the nano-silicon dioxide is 30nm and the specific surface area is 120m 2 / g.

[0041] In a specific embodiment of the present invention, the wetting and dispersing agent is a non-ionic modified fat derivative and a polyethylene glycol ester.

[0042] Example 1

[0043] Figure 1 A flow chart showing a method for preparing a hydrophobic cement-based material according to the present invention is shown.

[0044] like Figure 1 As shown, S110, 0.1% to 0.5% by weight of cellulose ether, 0.1% to 0.5% by weight of water reducing agent, 0.1% to 0.5% by weight of defoaming agent, 0.1% to 0.5% by weight of hydrophobic agent, 0.4% to 1.6% by weight of nano silicon dioxide and 0.1% to 1% by weight of wetting and dispersing agent are weighed and put into a high-speed dispersing mixer, and dispersed for a first preset time to obtain a premixed small material.

[0045] S120, putting 40% to 60% by weight of cement, 1% to 5% of silica fume, 30% to 60% of quartz sand and the premixed small materials into a zero-gravity mixer, and dispersing for a second preset time to obtain a hydrophobic cement-based material.

[0046] The first preset time is 15 minutes to 20 minutes, and the second preset time is 3 minutes to 5 minutes.

[0047] The preparation method of the above-mentioned hydrophobic cement-based material, by directly adding the organosilicon powder with slow-release properties as a hydrophobic agent into the cement-based material dry mix, effectively overcomes the existing defects of poor compatibility between the hydrophobic agent and water and cumbersome preparation process of the hydrophobic cement-based material. The organosilicon powder in the present invention has slow-release properties and can be directly used. At the same time, the added nano-silicon dioxide can promote cement hydration and hardening, reduce the influence of hydrophobic modification on mechanical properties, and the volcanic ash effect and the gel reaction of cement hydration products block the pores of concrete, reduce water absorption and improve the mechanical properties of cement-based materials at the same time; the application of wetting dispersant can improve the dispersibility of the hydrophobic agent in the cement matrix, ensure the uniform distribution of the hydrophobic components, give full play to the hydrophobic effect, and avoid the degradation of mechanical properties caused by uneven dispersion.

[0048] Preparation Example 1

[0049] S110, weighing cellulose ether, water reducing agent, defoaming agent, hydrophobic agent, nano silicon dioxide and wetting dispersant according to preset weights and putting them into a high-speed dispersing mixer, dispersing for 15 to 20 minutes to obtain a premixed small material;

[0050] Among them, cellulose ether is cellulose ether M500, water reducer is water reducer P29, defoamer is defoamer P841, hydrophobic agent is hydrophobic agent SHP50, wetting dispersant is wetting dispersant P588. Calculated by weight, the above premixed small materials include:

[0051] 0.30% cellulose ether M500, 0.25% water reducing agent P29, 0.10% defoaming agent P841, 0.20% hydrophobic agent SHP50, 1.60% nano silicon dioxide, and 0.18% wetting and dispersing agent P588.

[0052] S120, putting 42% by weight of cement Conch P·O52.5, 2.95% of silica fume, 15.90% of quartz sand 20-40 mesh, 26.5% of quartz sand 40-70 mesh, 10.02% of quartz sand 70-140 mesh and the above-mentioned premixed small materials into a zero-gravity mixer, and dispersing for 3 min to 5 min to obtain a hydrophobic cement-based material.

[0053] Preparation Example 2

[0054] S110, weighing 0.20% by weight of cellulose ether M500, 0.40% of water reducing agent P29, 0.12% of defoaming agent P841, 0.40% of hydrophobic agent SHP50, 2.00% of nano silicon dioxide and 0.24% of wetting and dispersing agent P588, and putting them into a high-speed dispersing mixer, dispersing for 15 to 20 minutes, to obtain a premixed small material;

[0055] S120, put 50% by weight of cement Conch P·O52.5, 3.50% of silica fume, 13.14% of quartz sand 20-40 mesh, 22% of quartz sand 40-70 mesh, 8.00% of quartz sand 70-140 mesh and the above-mentioned premixed small materials into a zero-gravity mixer, disperse for 3 minutes to 5 minutes, and obtain a hydrophobic cement-based material.

[0056] Preparation Example 3

[0057] S110, weighing 0.20% by weight of cellulose ether M500, 0.60% of water reducing agent P29, 0.32% of defoaming agent P841, 0.50% of hydrophobic agent SHP50, 1.00% of nano silicon dioxide and 0.15% of wetting and dispersing agent P588, and putting them into a high-speed dispersing mixer, dispersing for 15 to 20 minutes, to obtain a premixed small material;

[0058] S120, putting 60% by weight of cement Conch P·O52.5, 4.20% of silica fume, 9.23% of quartz sand 20-40 mesh, 17% of quartz sand 40-70 mesh, 6.80% of quartz sand 70-140 mesh and the above-mentioned premixed small materials into a zero-gravity mixer, and dispersing for 3 minutes to 5 minutes to obtain a hydrophobic cement-based material.

[0059] Control group 1

[0060] S110, weighing 0.30% by weight of cellulose ether M500, 0.25% by weight of water reducing agent P29, and 0.10% by weight of defoaming agent P841, and putting them into a high-speed dispersing mixer, dispersing for 15 to 20 minutes, to obtain a premixed small material;

[0061] S120, putting 42% by weight of cement Conch P·O52.5, 2.95% of silica fume, 15.90% of quartz sand 20-40 mesh, 26.50% of quartz sand 40-70 mesh, 12.00% of quartz sand 70-140 mesh and the above-mentioned premixed small materials into a zero-gravity mixer, and dispersing for 3 minutes to 5 minutes to obtain a hydrophobic cement-based material.

[0062] Control group 2

[0063] S110, weighing 0.20% by weight of cellulose ether M500, 0.40% by weight of water reducing agent P29, and 0.12% by weight of defoaming agent P841, and putting them into a high-speed dispersing mixer, dispersing for 15 to 20 minutes, to obtain a premixed small material;

[0064] S120, putting 50% by weight of cement Conch P·O52.5, 3.50% of silica fume, 13.14% of quartz sand 20-40 mesh, 22% of quartz sand 40-70 mesh, 10.64% of quartz sand 70-140 mesh and the above-mentioned premixed small materials into a zero-gravity mixer, and dispersing for 3 minutes to 5 minutes to obtain a hydrophobic cement-based material.

[0065] Control group 3

[0066] S110, weighing 0.20% by weight of cellulose ether M500, 0.60% by weight of water reducing agent P29, and 0.32% by weight of defoaming agent P841, and putting them into a high-speed dispersing mixer, dispersing for 15 to 20 minutes, to obtain a premixed small material;

[0067] S120, putting 60% by weight of cement Conch P·O52.5, 4.20% of silica fume, 9.23% of quartz sand 20-40 mesh, 17% of quartz sand 40-70 mesh, 8.45% of quartz sand 70-140 mesh and the above-mentioned premixed small materials into a zero-gravity mixer, and dispersing for 3 minutes to 5 minutes to obtain a hydrophobic cement-based material.

[0068] Table 1 below shows the specific formulation composition (weight percentage) of the above examples and the control group.

[0069]

[0070]

[0071] The mortars prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were mixed at a water-binder ratio of 0.4, cured for 28 days under the same conditions, and then tested as follows:

[0072] 1. Dry, then split, and test the contact angle of water inside the mortar. The contact angle is tested by a DSA25 standard contact angle meter. The drop size is 5μL each time. The first frame of the droplet on the surface of the cement-based material is selected to test the contact angle. The error deviation is about 2°.

[0073] 2. Test the flexural and compressive strength of the mortar in accordance with the requirements of "Test methods for physical properties of dry-mixed mortar" GB / T 29756-2013.

[0074] The test results are shown in the following table:

[0075] Example 1 Control group 1 Example 2 Control group 2 Example 3 Control group 3 Contact angle,° 151.8 25.3 154.8 26.6 158.4 24.9 Compressive strength, MPa 42.1 40.35 52.3 53.0 70.11 71.01 Flexural strength, MPa 10.0 9.6 11.7 11.2 12.53 11.15

[0076] It can be clearly seen from the above test results that the hydrophobic cement-based material prepared by the preparation method of the hydrophobic cement-based material provided by the present invention has a contact angle significantly larger than that of the cement-based material to which the organosilicon powder hydrophobic agent, nano-silica and wetting dispersant are not added, and the compressive strength and flexural strength are not adversely affected, and the mechanical properties are not reduced, and even become better.

[0077] In summary, the hydrophobic cement-based material and the preparation method thereof according to the present invention have the following advantages compared with the existing hydrophobic cement-based material preparation scheme:

[0078] 1. Directly add sustained-release silicone powder as a hydrophobic agent, effectively avoiding the common and cumbersome process of preparing and adding hydrophobic agents;

[0079] 2. Adding nano-silicon dioxide further provides hydrophobicity and has a reinforcing effect on cement-based materials, compensating for the decrease in mechanical properties caused by the addition of hydrophobic agents;

[0080] 3. Adding a wetting dispersant ensures the uniformity of the hydrophobic agent dispersion and overcomes the decrease in mechanical properties caused by uneven dispersion;

[0081] 4. The preparation process is simple, which significantly reduces the production cost.

[0082] 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. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A hydrophobic cement-based material, characterized in that: The following raw materials are included in percentage by weight: Cement 40% to 60%, silica fume 1% to 5%, quartz sand 30% to 60%, cellulose ether 0.1% to 0.5%, water reducer 0.1% to 0.5%, defoamer 0.1% to 0.5%, hydrophobic agent 0.1% to 0.5%, nano silicon dioxide 0.4% to 1.6%, wetting dispersant 0.1% to 1%; Wherein, the hydrophobic agent is organic silicon powder.

2. The hydrophobic cement-based material according to claim 1, characterized in that The cement is ordinary Portland cement.

3. The hydrophobic cement-based material according to claim 2, characterized in that The cellulose ether is methyl hydroxypropyl cellulose ether, and the viscosity is less than 10000 mPa·s.

4. The hydrophobic cement-based material according to claim 1, characterized in that The water reducing agent is a polycarboxylic acid-based high-performance water reducing agent.

5. The hydrophobic cement-based material according to claim 1, characterized in that The defoaming agent is polyethylene glycol vegetable oil.

6. The hydrophobic cement-based material according to claim 5, characterized in that The average diameter of the organosilicon powder is 300 μm, and the volume density is 600 g / l.

7. The hydrophobic cement-based material according to claim 5, characterized in that The average diameter of the nano-silicon dioxide is 30nm and the specific surface area is 120m 2 / g.

8. The hydrophobic cement-based material according to claim 5, characterized in that The dispersant is a non-ionic modified fat derivative and polyethylene glycol ester.

9. A method for preparing a hydrophobic cement-based material, characterized in that: Used for preparing the hydrophobic cement-based material according to any one of claims 1 to 8; the method comprises: 0.1% to 0.5% by weight of cellulose ether, 0.1% to 0.5% by weight of water reducing agent, 0.1% to 0.5% by weight of defoaming agent, 0.1% to 0.5% by weight of hydrophobic agent, 0.4% to 1.6% by weight of nano silicon dioxide and 0.1% to 1% by weight of wetting and dispersing agent are weighed and put into a high-speed dispersing mixer, and dispersed for a first preset time to obtain a premixed small material; 40% to 60% by weight of cement, 1% to 5% of silica fume, 30% to 60% of quartz sand and the premixed small materials are put into a zero-gravity mixer and dispersed for a second preset time to obtain a hydrophobic cement-based material.

10. The method for preparing a hydrophobic cement-based material according to claim 7, characterized in that: The first preset time is 15 minutes to 20 minutes, and the second preset time is 3 minutes to 5 minutes.

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