Super-hydrophobic modified high belite sulphoaluminate cement mortar and preparation method thereof
By using hydroxyl-terminated polydimethylsiloxane and nano-silica modified high-belite sulfoaluminate cement mortar, the problems of water absorption and durability of concrete materials are solved, achieving efficient hydrophobic properties and environmentally friendly modification, thereby improving the waterproof performance and service life of concrete.
Patent Information
- Application Number
- CN202510911046.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-02
- Publication Date
- 2025-10-17
AI Technical Summary
Existing concrete materials have microporous structures and hydrophilicity during the hardening process, resulting in high water absorption and susceptibility to corrosive ions, which affects structural durability and service life. Existing hydrophobic modifiers also pose environmental and safety hazards.
Hydroxyl-terminated polydimethylsiloxane and nano-silica were used as modifying materials. By mixing them with high belite sulfoaluminate cement, a low surface energy emulsion was formed, and superhydrophobic modified high belite sulfoaluminate cement mortar was prepared.
The prepared superhydrophobic modified cement mortar has excellent hydrophobic properties, with a static contact angle of up to 151.8°, a water absorption rate reduction of 75.26%, and good self-cleaning effect and mechanical durability.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of building materials, and particularly relates to a super-hydrophobic modified high-berlite sulphoaluminate cement mortar and a preparation method thereof. BACKGROUND
[0002] Concrete material is the most widely used building material in the world. Because of the advantages of easy availability and low cost of raw materials, high compressive strength, strong plasticity, etc., it not only occupies a dominant position in the construction of water conservancy and hydropower projects, but also is widely used in the fields of houses, roads, bridges, tunnels, etc. However, the volatilization of excess water during the hardening process of concrete leads to the existence of a large number of micro-pore structures inside the concrete, in addition, the surface energy of concrete is relatively high, which presents hydrophilicity, which makes the concrete material have strong water absorption, and thus causes a series of problems. For example, the water in the internal pores of concrete in the extremely cold environment expands in volume after freezing, which may cause cracks, shedding and other damage to the concrete structure. In addition, water may also carry Cl - , SO4 2- , CO3 2- and other erosion ions into the interior of the concrete. Since the concrete is an alkaline material, it may be subjected to chemical erosion such as chloride ion erosion, sulfate erosion, carbonation, etc. under the influence of these ions, thereby leading to the decline of structural strength and durability, and ultimately affecting the service life. Therefore, the study of improving the waterproof performance of concrete, hindering water and erosion ions from entering the interior of the concrete can improve the durability of concrete, reduce the maintenance cost of buildings, and prolong the service life, which has important significance for the development of water conservancy projects.
[0003] Research shows that the hydrophobic modification of cement-based materials can effectively improve the waterproof performance of the materials, thereby improving the durability and service life of the materials. Common methods for hydrophobic modification of cement-based materials include surface modification and overall modification. The mechanical properties of the hydrophobic coating prepared by the surface modification method are poor. Considering that the cement-based materials such as concrete may crack due to their own physical shrinkage during the service period, the hydrophobic coating may crack and lose its protective effect. At the same time, the hydrophobic coating may be worn or peeled off due to adverse environmental factors such as friction and chemical corrosion. In addition, the hydrophobic coating is easily damaged under the action of ultraviolet light or high temperature, and the hydrophobic performance decreases, so it needs to be regularly maintained and reapplied. Compared with the surface modification method, the cement-based material modified by the overall hydrophobic modification also has hydrophobic performance inside, which makes the material even if the surface is worn or cracked during use, the newly exposed surface still has hydrophobic performance. It can be seen that the long-term waterproof performance of the overall hydrophobic concrete is much better than that of the surface hydrophobic modified concrete, which greatly reduces the maintenance requirements. The existing technology includes using a stearic acid-ethanol solution as a hydrophobic agent, cooperating with ethanol evaporation to construct a rough structure, realizing the super-hydrophobic modification of cement mortar, and having a contact angle of 150.6° and a rolling angle of 9.5°. There is also a fluoralkylsilane added during mixing to cover the 80-mesh purple copper mesh to construct a rough structure to prepare a super-hydrophobic mortar with a contact angle of 154.2° and a rolling angle of 6.8°. Although the hydrophobicity and durability of the concrete modified by the hydrophobic additive are improved, different modifiers have their own limitations. The hydrophobic effect of fatty acids is not as good as that of fluorosilane, silane and siloxane. In addition, fatty acids are solid at room temperature and insoluble in water, so how to make them uniformly dispersed after mixing with cement is a difficult problem. Fluorosilane is difficult to degrade in the natural environment, it will accumulate in the body, and eventually affect humans as the food chain rises. At the same time, fluorosilane is toxic, so it poses environmental and health risks.
[0004] Therefore, it is urgent to develop a new type of hydrophobic cement material with good performance, uniform dispersion, environmental protection, and simple preparation. SUMMARY
[0005] The present application aims to at least partially solve one of the technical problems in the related art. To this end, the present application provides a super-hydrophobic modified high belite sulphoaluminate cement mortar and a preparation method thereof. The preparation method has the advantages of fast effect, convenient preparation, environmental protection and non-toxicity, and provides support for the good application of super-hydrophobic materials in the field of building materials.
[0006] To this end, the first aspect of the present application provides a preparation method of a super-hydrophobic modified high belite sulphoaluminate cement mortar, which comprises the following steps:
[0007] Mixing fine sand and nano-silica, performing first stirring treatment, adding high belite sulphoaluminate cement and synthetic fiber, performing second stirring treatment, to obtain dry material mixture;
[0008] Adding hydroxyl-terminated polydimethylsiloxane, tetraethoxysilane and dibutyl tin dilaurate into water, performing emulsification treatment, to obtain low surface energy emulsion;
[0009] Mixing the dry material mixture and the low surface energy emulsion, to obtain the super-hydrophobic modified high belite sulphoaluminate cement mortar.
[0010] The preparation method provided by the application uses hydroxyl-terminated polydimethylsiloxane and nano-silica as modified materials to prepare the super-hydrophobic modified high belite sulphoaluminate cement mortar.
[0011] According to the embodiment of the application, the mass ratio of the high belite sulphoaluminate cement, fine sand, nano-silica and synthetic fiber is 1:(1.0-1.1):(0.01-0.03):(0.005-0.010).
[0012] According to the embodiment of the application, the synthetic fiber comprises at least one of polypropylene fiber, polyester fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber and polyamide fiber.
[0013] According to the embodiment of the application, the time of the first stirring treatment is 5-8 minutes.
[0014] According to the embodiment of the application, the time of the second stirring treatment is 5-8 minutes.
[0015] According to the embodiment of the application, the mass ratio of the hydroxyl-terminated polydimethylsiloxane, tetraethoxysilane and dibutyl tin dilaurate is 1:(0.05-0.10):(0.05-0.10).
[0016] According to the embodiment of the application, the mass ratio of the high belite sulphoaluminate cement and the hydroxyl-terminated polydimethylsiloxane is 1:(0.01-0.03).
[0017] According to the embodiment of the application, the time of the emulsification treatment is 5-6 minutes.
[0018] According to the embodiment of the application, the water-binder ratio of the super-hydrophobic modified high belite sulphoaluminate cement mortar is 0.45-0.50.
[0019] According to an embodiment of the present application, the preparation method further comprises curing and drying the super-hydrophobic modified high-belite sulphoaluminate cement mortar to obtain a super-hydrophobic modified high-belite sulphoaluminate cement mortar block.
[0020] According to an embodiment of the present application, the curing temperature is 20-25 DEG C.
[0021] According to an embodiment of the present application, the curing relative humidity is 90-95%.
[0022] According to an embodiment of the present application, the curing time is 24-72 hours.
[0023] The present application provides a super-hydrophobic modified high-belite sulphoaluminate cement mortar prepared by the preparation method of the first aspect.
[0024] The super-hydrophobic modified high-belite sulphoaluminate cement mortar prepared by the preparation method of the present application has the advantages of rapid setting, convenience, environmental protection, etc.
[0025] The present application has the following beneficial effects over the prior art:
[0026] (1) The super-hydrophobic modified high-belite sulphoaluminate cement mortar is prepared by using hydroxyl-terminated polydimethylsiloxane and nano-silica as the modification material, and the cement mortar block obtained by curing and drying the cement mortar has excellent hydrophobic property, with the highest static contact angle of 151.8 DEG, and the water absorption rate can be reduced by 75.26% compared with the unmodified cement mortar block.
[0027] (2) The cement mortar block obtained by curing and drying the cement mortar has good self-cleaning effect and mechanical durability.
[0028] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS
[0029] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.
[0030] Figure 1 shows a flowchart of the preparation method provided by the present application;
[0031] Figure 2 shows the hydrophobicity test effect diagram of the super-hydrophobic modified high-belite sulphoaluminate cement mortar block prepared in Example 1 of the present application;
[0032] Figure 3A hydrophobicity test effect diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar block prepared in Example 2 of the present application is shown;
[0033] Figure 4 A hydrophobicity test effect diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar block prepared in Example 3 of the present application is shown;
[0034] Figure 5 A setting time comparison diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar prepared in Example 3 of the present application, the high belite sulphoaluminate cement mortar prepared in Comparative Example 1, and the commercially available ordinary portland cement mortar is shown;
[0035] Figure 6 A sample immersion water absorption rate comparison diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar prepared in Example 3 of the present application and the high belite sulphoaluminate cement mortar prepared in Comparative Example 1 is shown;
[0036] Figure 7 A self-cleaning test effect diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar block prepared in Example 3 of the present application is shown;
[0037] Figure 8 and Figure 9 A durability test effect diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar block prepared in Example 3 of the present application is shown;
[0038] Figure 10 A hydrophobicity test effect diagram of the high belite sulphoaluminate cement mortar block prepared in Comparative Example 1 of the present application is shown;
[0039] Figure 11 A hydrophobicity test effect diagram of the high belite sulphoaluminate cement mortar block prepared in Comparative Example 2 of the present application is shown;
[0040] Figure 12 A hydrophobicity test effect diagram of the high belite sulphoaluminate cement mortar block prepared in Comparative Example 3 of the present application is shown. DETAILED DESCRIPTION
[0041] Embodiments of the present application are described in detail below. The embodiments described below are exemplary only and are not intended to be limiting of the present application.
[0042] It should be noted that the terms "first", "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of the technical features. Thus, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.
[0043] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.
[0044] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meaning commonly understood by those skilled in the art to which the present invention belongs.
[0045] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention, but not excluding other contents.
[0046] As used herein, the terms "optionally," "optional," or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.
[0047] According to an embodiment of the present invention, a first aspect of the present invention provides a method for preparing a super-hydrophobic modified high-belite sulphoaluminate cement mortar, the preparation method comprising the following steps:
[0048] (1) fine sand and nano-silica are mixed and subjected to a first stirring process, high-belite sulphoaluminate cement and synthetic fiber are added and subjected to a second stirring process to obtain a dry material mixture.
[0049] Specifically, in step (1), the high-belite sulphoaluminate cement and the synthetic fiber can be added only after the nano-silica is mixed with the fine sand. If they are mixed at the same time, the nano-silica may agglomerate, thereby reducing the performance of the finished product.
[0050] According to a specific embodiment of the present invention, the mass ratio of the high-belite sulphoaluminate cement, fine sand, nano-silica and synthetic fiber is 1:(1.0-1.1):(0.01-0.03):(0.005-0.010). As some specific examples, the mass ratio of the high-belite sulphoaluminate cement, fine sand, nano-silica and synthetic fiber can be 1:1:0.01:0.005, 1:1.1:0.03:0.010, etc.
[0051] According to a specific embodiment of the present application, the kind of the synthetic fiber is not particularly limited, and as some specific examples, the synthetic fiber includes at least one of polypropylene fiber, polyester fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, and polyamide fiber. In particular, the synthetic fiber functions to increase roughness and reduce a rolling angle.
[0052] According to a specific embodiment of the present application, the time of the first stirring treatment is 5 min to 8 min, and as some specific examples, the time of the first stirring treatment can be 5 min, 6 min, 7 min, 8 min, etc.
[0053] According to a specific embodiment of the present application, the time of the second stirring treatment is 5 min to 8 min, and as some specific examples, the time of the second stirring treatment can be 5 min, 6 min, 7 min, 8 min, etc.
[0054] (2) Hydroxyl-terminated polydimethylsiloxane, tetraethoxysilane, and dibutyltin dilaurate are added to water, and emulsification treatment is performed to obtain a low-surface-energy emulsion.
[0055] In particular, the hydrophobic modification effect of the hydroxyl-terminated polydimethylsiloxane is better than that of polydimethylsiloxane that is not terminated by hydroxyl, and the reason is that there are a large number of hydroxyl groups in the high-blettite sulfoaluminate cement hydration product, and the use of hydroxyl-terminated polydimethylsiloxane can directly undergo dehydration condensation with the hydroxyl groups on the surface of the cement-based material, and graft a long carbon chain with low surface energy to the surface of the cement-based material. In addition, the hydroxyl-terminated polydimethylsiloxane also undergoes crosslinking reaction with the hydrolysis product of tetraethyl orthosilicate, i.e., orthosilicic acid, under the action of a catalyst to form a network structure, and the use of hydroxyl-terminated polydimethylsiloxane is more conducive to the occurrence of dehydration condensation.
[0056] According to a specific embodiment of the present application, the mass ratio of the hydroxyl-terminated polydimethylsiloxane, tetraethoxysilane, and dibutyltin dilaurate is 1:(0.05-0.10):(0.05-0.10), and as some specific examples, the mass ratio of the hydroxyl-terminated polydimethylsiloxane, tetraethoxysilane, and dibutyltin dilaurate can be 1:0.05:0.05, 1:0.10:0.10, etc.
[0057] According to a specific embodiment of the present application, the mass ratio of the high-blettite sulfoaluminate cement and the hydroxyl-terminated polydimethylsiloxane is 1:(0.01-0.03), and as some specific examples, the mass ratio of the high-blettite sulfoaluminate cement and the hydroxyl-terminated polydimethylsiloxane can be 1:0.01, 1:0.02, 1:0.03, etc.
[0058] According to a specific embodiment of the present application, the emulsification treatment is performed for 5-6 minutes. As some specific examples, the emulsification treatment can be performed for 5 minutes, 5.5 minutes, 6 minutes, etc. Specifically, the emulsification treatment is not particularly limited and, for example, a high-speed shearing emulsifier can be used.
[0059] (3) mixing the dry mixture and the low surface energy emulsion to obtain the super-hydrophobic modified high belite sulphoaluminate cement mortar.
[0060] Specifically, the main mineral components of the high belite sulphoaluminate cement include calcium sulphoaluminate dicalcium silicate (C2S), ferrite phase (C4AF), gypsum etc. The hydration equations thereof are shown in equation (1), equation (2) and equation (3), wherein H represents water (H2O), represents ettringite (AFt phase), represents monosulphate (AFm phase), AH3 represents aluminium hydroxide gel (Al(OH)3), C3S2H3 represents calcium silicate hydrate (C-S-H) gel, and CH represents calcium hydroxide (Ca(OH)2). AFt and AFm can be converted into each other.
[0061]
[0062] 2C2S + 4H → C3S2H3 + CH equation (3)
[0063] At the beginning of hydration, calcium sulphoaluminate reacts with gypsum and water to form ettringite, and when the gypsum is consumed, calcium sulphoaluminate reacts with water to form monosulphate. Because the reaction rate of C2S is extremely slow at the beginning of hydration, the initial reaction is mainly equation (1) and equation (2), i.e. the main hydration products are AFt, AFm and Al(OH)3 gel, and thus the Al(OH)3 gel is the main source of hydroxyl (-OH) in the hydration products of high belite sulphoaluminate cement. Although the hydration products of ordinary Portland cement also contain a large amount of hydroxyl, the source thereof is the hydration reaction of tricalcium silicate (C3S), as shown in equation (4). It can be seen that the sources of hydroxyl in the hydration products of high belite sulphoaluminate cement and ordinary Portland cement are different. Therefore, when hydroxyl-terminated polydimethylsiloxane and nano-silica are used as the modifying agent, the modification mechanisms thereof for the hydration products of high belite sulphoaluminate cement and ordinary Portland cement are different.
[0064] 2C3S + 6H → C3S2H3 + 3CH equation (4)
[0065] According to a specific embodiment of the present application, the water-binder ratio of the super-hydrophobic modified high belite sulphoaluminate cement mortar is 0.45-0.50, and as some specific examples, the water-binder ratio of the super-hydrophobic modified high belite sulphoaluminate cement mortar can be 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, etc. Specifically, the water-binder ratio refers to the mass ratio of water to high belite sulphoaluminate cement.
[0066] According to a specific embodiment of the present application, the mixing method of the dry mixture and the low surface energy emulsion is not particularly limited, for example, the cement mortar mixer can be stirred at a low speed for 2 min, and then stirred at a high speed for 2 min. Specifically, after the mixing is completed, the super-hydrophobic modified high belite sulphoaluminate cement mortar can also be poured into a mold and bubbles are removed by vibration.
[0067] According to a specific embodiment of the present application, the preparation method further comprises curing and drying the super-hydrophobic modified high belite sulphoaluminate cement mortar to obtain a super-hydrophobic modified high belite sulphoaluminate cement mortar block.
[0068] According to a specific embodiment of the present application, the curing temperature is 20-25℃, and as some specific examples, the curing temperature can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, etc.
[0069] According to a specific embodiment of the present application, the relative humidity of the curing is 90%-95%, and as some specific examples, the relative humidity of the curing can be 90%, 91%, 92%, 93%, 94%, 95%, etc.
[0070] According to a specific embodiment of the present application, the curing time is 24-72h, and as some specific examples, the curing time can be 24h, 48h, 72h, etc.
[0071] Specifically, when polypropylene fibers are used as synthetic fibers, the specific steps of the preparation method can refer to Figure 1 .
[0072] According to an embodiment of the present application, the second aspect of the present application provides a super-hydrophobic modified high belite sulphoaluminate cement mortar obtained by the preparation method of the first aspect.
[0073] The super-hydrophobic modified high belite sulphoaluminate cement mortar prepared by the preparation method provided by the present application has the advantages of rapid setting, convenience, environmental protection, etc.
[0074] The schemes of the present application will be explained below with reference to examples. Those skilled in the art will understand that the examples below are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If no specific technique or condition is specified in the examples, the technique or condition described in the literature in the art or according to the product manual is used. If no manufacturer of the reagent or instrument is specified, it is a conventional product that can be obtained commercially.
[0075] Example 1
[0076] The present example provides a method for preparing a super-hydrophobic modified high-early-strength sulphoaluminate cement mortar, which comprises the following steps:
[0077] (1) 0.3 g of nano-silica is mixed with 30 g of fine sand, stirred for 5 min, and then 30 g of high-early-strength sulphoaluminate cement and 0.15 g of polypropylene fiber are added and stirred for 5 min;
[0078] (2) 0.3 g of hydroxyl-terminated polydimethylsiloxane, 0.015 g of tetraethoxysilane and 0.015 g of dibutyltin dilaurate are added to 15 g of deionized water, and a high-speed shearing emulsifier is used to stir at a speed of 9.0 kr / min for 5 min to obtain a low surface energy emulsion;
[0079] (3) The low surface energy emulsion prepared in step (2) is poured into the fine sand dry mixture prepared in step (1), and a cement mortar stirrer is used to stir at low speed for 2 min and then at high speed for 2 min to obtain a super-hydrophobic modified high-early-strength sulphoaluminate cement mortar, which is poured into a mold and bubbles are removed by vibration;
[0080] (4) The demolded sample obtained in step (3) is cured in a standard curing room at 20-25°C and 90-95% relative humidity for 72 h and then dried in air to form a block of super-hydrophobic modified high-early-strength sulphoaluminate cement mortar.
[0081] The mortar mixing material setting time is determined by using a mortar setting time tester according to the standard JGJ70-2009, and the initial setting time of the above sample is measured to be 25 min and the final setting time is measured to be 33 min.
[0082] The contact angle is measured by using a contact angle measuring instrument, and the contact angle of the above super-hydrophobic modified high-early-strength sulphoaluminate cement mortar block is measured to be 129.8°, as shown in Figure 2 .
[0083] The above super-hydrophobic modified high-early-strength sulphoaluminate cement mortar block is placed on a 600-mesh sandpaper, the sandpaper is fixed, and the lower surface of the sample is slid at a constant speed with a pressure of 656 Pa, and the contact angle is 129.8° after mutual friction for 20 m, which has almost no change.
[0084] Example 2
[0085] The present example provides a method for preparing a super-hydrophobic modified high belite sulphoaluminate cement mortar, the method comprising the following steps:
[0086] (1) 0.3 g nano-silica is mixed with 30 g fine sand, stirred for 5 min, then 30 g high belite sulphoaluminate cement and 0.15 g polypropylene fiber are added, stirred for 5 min;
[0087] (2) 0.6 g hydroxyl-terminated polydimethylsiloxane, 0.03 g tetraethoxysilane and 0.03 g dibutyltin dilaurate are added to 15 g deionized water, stirred at a speed of 9.0 kr / min for 5 min using a high-speed shearing emulsifier to obtain a low surface energy emulsion;
[0088] (3) The low surface energy emulsion prepared in step (2) is poured into the fine sand dry mixture prepared in step (1), and a cement mortar stirrer is used to stir at low speed for 2 min and then at high speed for 2 min to obtain a super-hydrophobic modified high belite sulphoaluminate cement mortar, which is poured into a mold and bubbles are removed by vibration;
[0089] (4) The demolded sample obtained in step (3) is cured in a standard curing room at 20-25°C and 90-95% relative humidity for 72 h, then dried in air to form a super-hydrophobic modified high belite sulphoaluminate cement mortar block.
[0090] The mortar mixing material setting time is determined by a mortar setting time tester according to standard JGJ70-2009, and the initial setting time of the above sample is measured to be 26 min and the final setting time is 31 min.
[0091] The contact angle is measured by a contact angle measuring instrument, and the contact angle of the above super-hydrophobic modified high belite sulphoaluminate cement mortar block is measured to be 144.0°, as shown in Figure 3 .
[0092] The above super-hydrophobic modified high belite sulphoaluminate cement mortar block is placed on a 600-mesh sandpaper, the sandpaper is fixed, and the lower surface of the sample is slid at a constant speed with a pressure of 656 Pa, and the contact angle is 144.0° after mutual friction for 20 m, which has almost no change.
[0093] Example 3
[0094] The present example provides a method for preparing a super-hydrophobic modified high belite sulphoaluminate cement mortar, the method comprising the following steps:
[0095] (1) 0.6 g nano-silica was mixed with 30 g fine sand, stirred for 5 min, then 30 g high belite sulphoaluminate cement and 0.15 g polypropylene fiber were added and stirred for 5 min;
[0096] (2) 0.6 g hydroxyl-terminated polydimethylsiloxane, 0.03 g tetraethoxysilane and 0.03 g dibutyltin dilaurate were added to 15 g deionized water, and a high-speed shearing emulsifier was used to stir at a speed of 9.0 kr / min for 5 min to obtain a low surface energy emulsion;
[0097] (3) The low surface energy emulsion prepared in step (2) was poured into the fine sand dry mixture prepared in step (1), and a cement mortar stirrer was used to stir at low speed for 2 min and then at high speed for 2 min to obtain a super-hydrophobic modified high belite sulphoaluminate cement mortar, which was poured into a mold and bubbles were removed by vibration;
[0098] (4) The demolding sample obtained in step (3) was cured in a standard curing room at 20-25°C and 90-95% relative humidity for 72 h, then dried in air to form a super-hydrophobic modified high belite sulphoaluminate cement mortar block.
[0099] The mortar setting time tester was used to determine the setting time of the mortar mixture according to the standard JGJ70-2009, and the initial setting time of the above sample was measured to be 27 min and the final setting time was 33 min.
[0100] The contact angle was measured by a contact angle measuring instrument, and the contact angle of the above super-hydrophobic modified high belite sulphoaluminate cement mortar block was measured to be 151.8°, as shown in Figure 4 .
[0101] The above super-hydrophobic modified high belite sulphoaluminate cement mortar block was placed on a 600-mesh sandpaper, the sandpaper was fixed, and the lower surface of the sample was slid at a constant speed with a pressure of 656 Pa, and the contact angle was 151.8° after mutual friction for 20 m, which showed almost no change.
[0102] The comparison chart of the setting time of the super-hydrophobic modified high belite sulphoaluminate cement mortar prepared in this example and the setting time of the commercially available ordinary portland cement mortar is shown in Figure 5 , the sample immersion water absorption rate of the super-hydrophobic modified high belite sulphoaluminate cement mortar prepared in this example is shown in Figure 6 , the self-cleaning test effect diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar block prepared in this example is shown in Figure 7 , and the durability test effect diagram of the super-hydrophobic modified high belite sulphoaluminate cement mortar block prepared in this example is shown in Figure 8 and 9 , wherein Figure 8To use a blade to draw an interlaced "X" mark on the surface of the mortar, place the mortar on the test bench, then drop a water droplet dyed with methylene blue reagent on the mark on the surface of the mortar, Figure 9 To use a hammer to break the mortar block, take a small piece, and drop a water droplet dyed with methylene blue reagent on the fracture surface thereof.
[0103] Comparative Example 1
[0104] This comparative example provides a preparation method of a high belite sulphoaluminate cement mortar, which comprises the following steps:
[0105] (1) 30 g of fine sand, 30 g of high belite sulphoaluminate cement, and 0.15 g of polypropylene fiber are mixed, and stirred for 5 min;
[0106] (2) 15 g of deionized water is poured into the dry powder sand mixture prepared in step (1), and a cement mortar stirrer is used to stir at low speed for 2 min and at high speed for 2 min, to obtain a high belite sulphoaluminate cement mortar, which is poured into a mold and deaerated by vibration;
[0107] (3) The demolding sample obtained in step (2) is dried in air after being cured in a standard curing room at 20-25°C and 90-95% relative humidity for 72 h, to obtain a high belite sulphoaluminate cement mortar block.
[0108] The mortar mixture setting time is determined by using a mortar setting time tester according to the standard JGJ70-2009, and the initial setting time of the above sample is measured to be 25 min, and the final setting time is measured to be 30 min.
[0109] The contact angle is measured by using a contact angle measuring instrument, and the contact angle of the above high belite sulphoaluminate cement mortar block is measured to be 0°, as shown in Figure 10 .
[0110] The comparative diagram of the setting time of the high belite sulphoaluminate cement mortar prepared in this comparative example and the setting time of the commercially available ordinary portland cement mortar is shown in Figure 5 , and the sample immersion water absorption rate of the high belite sulphoaluminate cement mortar prepared in this comparative example is shown in Figure 6 .
[0111] Comparative Example 2
[0112] The difference between this comparative example and Example 1 is that in step (1), nano-silicon dioxide, fine sand, high belite sulphoaluminate cement, and polypropylene fiber are mixed at the same time, and stirred for 5 min.
[0113] The mortar mixture setting time was determined by using a mortar setting time tester according to the standard JGJ70-2009, and the initial setting time of the sample was 26 min and the final setting time was 33 min.
[0114] The contact angle of the high belite sulphoaluminate cement mortar block was measured by using a contact angle measuring instrument, and the contact angle was 123.3°, as shown in Figure 11 .
[0115] The high belite sulphoaluminate cement mortar block was placed on a 600-mesh sandpaper, the sandpaper was fixed, and the lower surface of the sample was slid at a constant speed with a pressure of 656 Pa. After 20 m of mutual friction, the contact angle was 123.3°, and there was almost no change.
[0116] Comparative Example 3
[0117] The difference between this comparative example and Example 1 is that the polydimethylsiloxane used in step (2) has no hydroxyl end-capping.
[0118] The mortar mixture setting time was determined by using a mortar setting time tester according to the standard JGJ70-2009, and the initial setting time of the sample was 24 min and the final setting time was 32 min.
[0119] The contact angle of the high belite sulphoaluminate cement mortar block was measured by using a contact angle measuring instrument, and the contact angle was 119.4°, as shown in Figure 12 .
[0120] The high belite sulphoaluminate cement mortar block was placed on a 600-mesh sandpaper, the sandpaper was fixed, and the lower surface of the sample was slid at a constant speed with a pressure of 656 Pa. After 20 m of mutual friction, the contact angle was 119.4°, and there was almost no change.
[0121] The results of the sample tests of the examples and Comparative Example 1 show that, after the hydroxyl-terminated polydimethylsiloxane and nano-silica are added, the sample of the example forms a multi-layer rough structure of super-hydrophobic concrete, and the prepared sample has the necessary conditions to achieve the super-hydrophobic function. The surface and inner surface of the sample of Example 3 exhibit good super-hydrophobicity, and the hydrophobic angle can be as high as 151.8°. The initial setting time and final setting time of the sample of the example and the comparative example are small, and are much smaller than the initial setting time of 135 min and the final setting time of 195 min of ordinary Portland cement. The immersion water absorption rate of Example 3 can be reduced by 75.26% compared with Comparative Example 1, and the sample of Example 3 has good self-cleaning effect and mechanical durability. The results of Example 1 and Comparative Example 2 show that, if the nano-silica is directly stirred with the high-berlet sulphoaluminate cement, the agglomeration of the nano-silica will be caused, thereby affecting the surface roughness and causing the contact angle to slightly decrease. The results of Example 1 and Comparative Example 3 show that, if the polydimethylsiloxane is used instead of the hydroxyl-terminated polydimethylsiloxane, the dehydration condensation reaction and the reticulation of the cross-linking reaction will be affected, and the contact angle will slightly decrease. In summary, the preparation method provided by the present application has the advantages of simple preparation process, safe and environmentally friendly materials and reagents, good hydrophobic effect, and wide application prospect in the protection of hydraulic concrete.
[0122] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.
[0123] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.
Claims
1. A method for preparing a super-hydrophobic modified high-belite sulphoaluminate cement mortar, characterized in that: The preparation method comprises the following steps: Mixing fine sand and nano-silica, performing a first stirring process, adding high-belite sulphoaluminate cement and synthetic fiber, performing a second stirring process, to obtain a dry material mixture; Hydroxyl-terminated polydimethylsiloxane, tetraethoxysilane, and dibutyltin dilaurate are added to water and emulsified to obtain a low surface energy emulsion; The dry material mixture and the low surface energy emulsion are mixed to obtain the super-hydrophobic modified high-belite sulphoaluminate cement mortar.
2. The preparation method according to claim 1, characterized in that The mass ratio of the high-belite sulphoaluminate cement, fine sand, nano-silicon dioxide and synthetic fiber is 1: (1.0-1.1): (0.01-0.03): (0.005-0.010).
3. The preparation method according to claim 1, characterized in that The synthetic fiber includes at least one of polypropylene fiber, polyester fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, and polyamide fiber.
4. The preparation method according to claim 1, characterized in that The first stirring treatment time is 5min to 8min; Optionally, the second stirring treatment lasts for 5 to 8 minutes.
5. The preparation method according to claim 1, characterized in that The mass ratio of the hydroxyl-terminated polydimethylsiloxane, tetraethoxysilane and dibutyltin dilaurate is 1:(0.05-0.10):(0.05-0.10).
6. The preparation method according to claim 1, characterized in that The mass ratio of the high-belite sulphoaluminate cement to the hydroxyl-terminated polydimethylsiloxane is 1:(0.01-0.03).
7. The preparation method according to claim 1, characterized in that The emulsification treatment time is 5 minutes to 6 minutes.
8. The preparation method according to claim 1, characterized in that The water-to-binder ratio of the super-hydrophobic modified high-belite sulphoaluminate cement mortar is 0.45-0.
50.
9. The preparation method according to claim 1, characterized in that The preparation method further comprises: curing and drying the super-hydrophobic modified high-belite sulphoaluminate cement mortar to obtain a super-hydrophobic modified high-belite sulphoaluminate cement mortar block; Optionally, the curing temperature is 20°C to 25°C; Optionally, the relative humidity of the curing is 90% to 95%; Optionally, the curing time is 24 hours to 72 hours.
10. A super-hydrophobic modified high-belite sulphoaluminate cement mortar obtained according to the preparation method according to any one of claims 1 to 9.