Self-cleaning organic-inorganic hybrid waterproof coating for concrete and preparation method thereof
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to a self-cleaning organic-inorganic hybrid waterproof coating for concrete and a preparation method thereof.
Background
Concrete is well known as the most commonly used inorganic nonmetallic building material for humans. At present, along with the rapid and continuous development of Chinese economy, the concrete structure is widely applied to various fields of construction, traffic, water conservancy, agriculture, electric power and the like with the advantages of high strength, easy construction, convenient material taking, strong shape adaptability and the like. However, due to the influence of various environmental factors, even if the structural design is reasonable and the construction is correct, the concrete is often degraded in the service period, wherein one important degradation influencing factor is water, and the existence of water enables carbon dioxide to easily enter the concrete to be carbonized, and steel bar corrosion, sulfate erosion and the like can be caused. These erosion effects cause leakage problems, which affect the durability of the structure, reduce the service life of the structure, and increase maintenance costs, and seriously damage the property and life safety of people, so that waterproofing is imperative. At present, waterproof materials are various, inorganic waterproof materials are mainly permeable crystallization waterproof agents, organic waterproof materials mainly comprise acrylic emulsion, polyurea, polyurethane, epoxy resin, organic silicon and the like, but the existing waterproof materials have the defects of different degrees, and the organic materials are excellent in toughness, but have the defects of poor ageing resistance, low strength and the like; however, inorganic materials have a problem of poor brittleness, etc. although they have a good aging resistance.
The patent with application number of CN202111198564.7 discloses an inorganic water-based permeable crystalline waterproof material, a preparation method and a use method thereof, wherein the waterproof material comprises the main components of silicate, carbonate, caustic soda, active alumina, water-based siloxane, tartaric acid, sodium gluconate, active silicon dioxide, volcanic ash, bentonite, a catalyst, an auxiliary agent and distilled water. The waterproof agent can penetrate into the concrete, and silicate reacts with calcium ions in the cement to generate C-S-H gel, so that the cement and sand are adhered together, and micropores and capillary channels are blocked. However, the amount of calcium ions in cement is limited, and the gel produced is limited. The performance effect of the product is not very specific, the waterproof effect is unknown, and the material can only seal micro-pores. In our patent, not only the inorganic silicate solution reacts with calcium ions to form C-S-H gel, but also two inorganic active components react with calcium hydroxide in cement to form water-insoluble crystalline substances such as ettringite and calcium hydrophosphate, and the more the crystalline substances are, the better the blocking effect is. The patent with the application number of CN201710047477.9 discloses a preparation method of a cement-based permeable crystalline material, which mainly utilizes the reaction of sodium metasilicate pentahydrate, calcium chloride and calcium magnesium ions in cement to generate silicic acid gel so as to realize waterproof plugging, but the material only contains rigid aggregates such as silicate cement, quartz sand, fly ash and the like, and the problems of low flexibility, high brittleness, poor mechanical property and the like of the traditional cement-based permeable crystalline material are not solved, so that the problems of cracking and the like of concrete still occur easily, and the service life is not obviously prolonged. The patent with the application number of CN202210084152.9 discloses a high-water-resistance polyurethane waterproof coating and a preparation method thereof, and the waterproof coating has good water resistance, improves the adhesion between the polyurethane waterproof coating and a wet base surface, and is safe and environment-friendly. However, the coating has complex preparation process, is an AB component and is more inconvenient to construct.
In summary, the prior art has the following drawbacks: (1) The penetration depth of the inorganic waterproof material is unknown, the waterproof effect is limited, and the material has high brittleness and poor mechanical property. (2) The organic waterproof material has complex preparation process, inconvenient construction, unfriendly environment and poor ageing resistance.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the invention provides the waterproof coating with good impermeability, good carbonization resistance of cement concrete and excellent comprehensive mechanical property and the preparation method thereof.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the self-cleaning organic-inorganic hybrid waterproof coating for concrete comprises the following components in percentage by mass:
18.4 to 35.7 percent of deionized water, 33.5 to 46.9 percent of acrylic emulsion, 0.0067 to 0.0134 percent of sodium chloride, 0.0134 to 0.0268 percent of sodium hydroxide, 0.067 to 0.134 percent of water-soluble sulfate, 0.067 to 0.134 percent of water-soluble hydrogen phosphate, 1.3 to 2.7 percent of organosilicon solution, 1.2 to 6.8 percent of organosilane, 20.0 to 33.5 percent of inorganic silicon solution and 0.067 to 0.14 percent of ultraviolet absorber.
Specifically, the acrylic emulsion is selected from any one or more than two of pure acrylic emulsion, silicone acrylic emulsion and styrene acrylic emulsion.
Specifically, the water-soluble sulfate is selected from any one or more than two of sodium sulfate, potassium sulfate and zinc sulfate.
Specifically, the water-soluble hydrogen phosphate is selected from any one or more than two of sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate and dipotassium hydrogen phosphate.
Specifically, the organic silicon solution is selected from any one or two of methyl sodium silicate aqueous solution and methyl potassium silicate aqueous solution; the mass concentration of the organic silicon solution is 30-50%.
Specifically, the inorganic silicon solution is selected from any one or two of sodium silicate aqueous solution and potassium silicate aqueous solution; the mass concentration of the inorganic silicon solution is 20-45%.
Specifically, the organosilane is selected from any two or more of simethicone, polymethylhydrosiloxane, gamma-glycidoxypropyl trimethoxysilane and 3-glycidoxypropyl methyl diethoxysilane; the mass concentration of the organosilane is more than 95%.
Specifically, the ultraviolet absorbent is selected from one or more than two of diphenyl ketone, benzotriazole, salicylate and triazine.
The self-cleaning organic-inorganic hybrid waterproof material for concrete prepared by the invention is uniformly distributed on the surface of the concrete by adopting construction modes such as smearing or spraying, wherein a part of anions in inorganic water-soluble active components, namely silicate solution, sulfate solution and hydrogen phosphate, penetrate into the concrete and continuously react with cations such as calcium ions dissolved in the concrete to form slightly soluble or insoluble crystalline substances such as water-insoluble hydrated calcium silicate, ettringite, calcium hydrophosphate and the like, and capillary channels are blocked, so that the compactness and the waterproof performance of a matrix are improved. The ionic reaction equation is:
3CaO·Al 2 O 3 +3Ca 2+ +3SO 4 2- +32H 2 O=3CaO·Al 2 O 3 ·3CaSO 4 ·32H 2 O↓
the other part of inorganic film forming component and organic component forms a compact flexible film with hydrophobic property on the surface, and the principle is as follows:
the organosilane hydrolyzes to form silanol, wherein R represents an organic group (exemplified by 3-glycidoxypropyl methyldiethoxysilane)
RSi(OCH 2 CH 3 ) 3 +3H 2 O→RSi(OH) 3 +3CH 3 CH 2 OH
1) Condensation of silanol with silanol to form oligomers
2) The silicate solution is hydrolyzed to generate silicon hydroxyl bond, wherein M represents alkali metal element
3) The hydroxyl groups in the oligomer being linked to hydroxyl groups in the silicate to form Si-O-Si bonds
4) The organic R groups in the oligomer being bound to an acrylic emulsion (styrene-acrylic, for example)
5) Acrylic emulsion crosslinking (styrene-acrylic as an example)
Thereby forming a flexible hydrophobic coating film, which prevents intrusion of water. The organic film-forming component and the inorganic active component act together, so that the double-effect waterproof plugging of the matrix is effectively realized, the impermeability of the matrix is obviously improved, and the service life of the concrete building is prolonged.
In the above equation, n and X are both numerical parameters, and may be selected by those skilled in the art according to specific needs.
Furthermore, the invention also discloses a preparation method of the self-cleaning organic-inorganic hybrid waterproof coating for concrete, which comprises the following steps:
(1) Mixing deionized water, sodium chloride, sodium hydroxide, water-soluble sulfate and water-soluble hydrogen phosphate, fully stirring the solution, sequentially adding an organic silicon solution and an inorganic silicon solution, uniformly mixing, and stirring until the solution is clear to obtain a solution A;
(2) Slowly adding organosilane under the stirring state of the acrylic emulsion, and fully stirring until the solution has no sediment and no layering, so as to obtain a solution B;
(3) And (3) slowly adding the solution A in the step (1) into the solution B in the stirring state of the solution B in the step (2), fully stirring until the solution is completely dissolved and no precipitate exists, slowly adding an ultraviolet absorbent, and uniformly mixing to obtain the ultraviolet absorbent.
Compared with the prior art, the invention has the following advantages:
(1) The waterproof coating has double-effect waterproof effect, and the active components in the material, namely, the anions in the water-soluble silicate, the sulfate and the hydrogen phosphate, quickly permeate into the base material under the capillary siphoning action of the cement concrete base material, react with cations such as calcium ions and the like in the cement concrete base material, generate insoluble crystalline substances such as calcium silicate hydrate, calcium hydrophosphate, ettringite and the like, block the internal pores of the base material and strengthen the impermeability of the base material. The silicate solution and the silane coupling agent in the material are hydrolyzed to generate silanol, the silanol and the silanol are condensed to form an oligomer, the oligomer is connected with hydroxyl in silicate to form a Si-O-Si bond with flexibility, a compact waterproof flexible hydrophobic film is formed on the surface of the cement concrete substrate, and the compact waterproof flexible hydrophobic film and the active components act together to form double-effect protection, so that the waterproof effect is greatly enhanced, and the comprehensive mechanical property of the coating is excellent.
(2) The invention generates crystallization type insoluble substances to block pores by adding active components, namely silicate, sulfate and hydrogen phosphate anions to react with cations such as calcium ions and the like in the concrete.
(3) According to the invention, the silane hydrophobing agent is added to improve the hydrophobic effect of the waterproof material, so that the impermeability and self-cleaning property of the cement concrete matrix are further improved.
(4) The invention provides an alkaline environment for the system by adding sodium hydroxide, and effectively ensures the stable activity of the organic-inorganic hybrid waterproof coating.
(5) According to the invention, the acrylic emulsion is added to form a film-forming component together with the organic silicon solution and the inorganic silicon solution, the organic silicon component and the inorganic silicon component are hybridized, and a flexible chain segment in the organic component is introduced into the inorganic component, so that the film-forming flexibility and the adhesive force with a substrate are improved, the integrity of a coating film formed by coating the material on the substrate is ensured, and the substrate is well protected.
(6) The waterproof material disclosed by the invention has the characteristics of simple preparation method, simple and convenient construction process, strong controllability, good impermeability, high mechanical strength, good flexibility and the like, and the defect of double-material mixing and reuse of some organic materials is abandoned. The water-proof, carbonization-resistant and chloride ion-resistant water-proof cement-based cured fishpond and highway bridge can be applied to balconies, basements, building outer walls, cement-based cured fishponds, highway bridges and the like, and the water-proof property provides a self-cleaning function for the building.
Drawings
The foregoing and/or other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings and detailed description.
FIG. 1 is a film formation profile of the coating of example 1 applied to a cement mortar block.
FIG. 2 is a graph showing the results of static contact angle measurements of the surface of a blank cement coupon and a cement coupon coated with a water-resistant coating of the present invention.
FIG. 3 is a XRD pattern representing the hydration product of a blank cement block and a cement block coated with a water-resistant coating of the present invention, and an enlarged XRD pattern of a specific hydration product.
FIG. 4 is a cross-sectional water penetration profile of a coated and uncoated water-repellent coating substrate after a permeation resistance test.
Detailed Description
The invention will be better understood from the following examples.
Example 1
The self-cleaning organic-inorganic hybrid waterproof material for concrete comprises the following components in mass percent: 26.655g of deionized water, 0.01g of sodium chloride, 0.02g of sodium hydroxide, 0.1g of sodium sulfate and 0.1g of disodium hydrogen phosphate are weighed and added into a glass reactor in sequence, and are fully stirred until the solution is complete. Adding 1g of methyl sodium silicate solution, 10g of sodium silicate solution and 10.53g of potassium silicate solution, and stirring until the solutions are uniformly mixed to obtain solution A; 25g of styrene-acrylic emulsion is measured, and then 1.1g of organosilane (0.5 g of gamma-glycidoxypropyl trimethoxysilane, 0.4g of 3-glycidoxypropyl methyl diethoxysilane and 0.2g of simethicone) is slowly added and stirred until the mixture is completely dissolved, and layering and precipitation are avoided, so that a solution B is obtained; then slowly adding the solution A into the solution B, fully stirring until no layering and no precipitation exist, finally slowly adding 0.05g of benzophenone, and uniformly mixing to obtain a finished product.
Example 2
The self-cleaning organic-inorganic hybrid waterproof material for concrete comprises the following components in mass percent: 25.938g of deionized water, 0.007g of sodium chloride, 0.01g of sodium hydroxide, 0.08g of zinc sulfate and 0.08g of monopotassium phosphate are sequentially added into a glass reactor, and fully stirred until the solution is complete. Then adding 1.5g of methyl potassium silicate solution, 5g of sodium silicate solution and 10g of potassium silicate solution, and stirring until the solutions are uniformly mixed to obtain solution A; 30g of pure acrylic emulsion is measured, and then 2.0g of organosilane (0.5 g of gamma-glycidoxypropyl trimethoxysilane, 1.0g of 3-glycidoxypropyl methyl diethoxysilane and 0.5g of polymethyl hydrogen siloxane) is slowly added and stirred until the mixture is completely dissolved, and layering and precipitation are avoided, so that a solution B is obtained; then slowly adding the solution A into the solution B, fully stirring until no layering and no precipitation exist, finally slowly adding 0.05g of salicylates, and uniformly mixing to obtain the finished product.
Example 3
The self-cleaning organic-inorganic hybrid waterproof material for concrete comprises the following components in mass percent: 15.2g of deionized water, 0.005g of sodium chloride, 0.01g of sodium hydroxide, 0.05g of sodium sulfate and 0.05g of sodium dihydrogen phosphate are weighed and added into a glass reactor in sequence, and are fully stirred until the solution is complete. Then adding 2g of methyl potassium silicate solution, 15g of sodium silicate solution and 10g of potassium silicate solution, and stirring until the solutions are uniformly mixed to obtain solution A; 30g of silicone-acrylic emulsion is measured, and then 2.3g of organosilane (gamma-glycidoxypropyl trimethoxysilane 0.8g, 3-glycidoxypropyl methyl diethoxysilane 1.0g and polymethylhydrosiloxane 0.5 g) is slowly added and stirred until the mixture is completely dissolved, and layering and precipitation are avoided, so that a solution B is obtained; and then slowly adding the solution A into the solution B, fully stirring until no layering and no precipitation exist, and finally slowly adding 0.05g of benzotriazole, and uniformly mixing to obtain a finished product.
Example 4
The self-cleaning organic-inorganic hybrid waterproof material for concrete comprises the following components in mass percent: 13.74g of deionized water, 0.005g of sodium chloride, 0.01g of sodium hydroxide, 0.05g of zinc sulfate and 0.05g of disodium hydrogen phosphate are sequentially added into a glass reactor, and the mixture is fully stirred until the mixture is completely dissolved. Then adding 2g of methyl sodium silicate solution and 20.77g of potassium silicate solution, and stirring until the solutions are uniformly mixed to obtain solution A; 35g of styrene-acrylic emulsion is measured, and then 2.94g of organosilane (1.0 g of gamma-glycidoxypropyl trimethoxysilane, 0.8g of 3-glycidoxypropyl methyl diethoxysilane and 1.14g of simethicone) is slowly added and stirred until the mixture is completely dissolved, and layering and precipitation are avoided, so that a solution B is obtained; and then slowly adding the solution A into the solution B, fully stirring until layering and precipitation are avoided, and finally slowly adding 0.1g of triazines, and uniformly mixing to obtain the finished product.
The adhesion and hardness of the coatings were tested according to GB/T6739-2006 pencil test for hardness of coating films, GB/T9286-1998 cross-cut test for paint films of colored and clear paints. The coatings prepared in examples 1 to 4 were applied to a cement paste block for 24 hours and then subjected to static contact angle test using a surface contact angle meter. After the coatings of examples 1 to 4 were applied to standard cement mortar test blocks of different curing ages for 24 hours, a cement mortar press was used for compressive strength testing. The permeation resistance of the coating was characterized by using a digital mortar penetrometer in a mode of pressurizing stepwise 0.1MPa per hour (pressurizing stepwise from 1.2MPa to 1.9MPa for 8 hours). The blank test blocks were not subjected to the coating treatment. The results are shown in Table 1, and it can be seen that the coating film formed by coating the organic-inorganic hybrid waterproof material developed by the invention on the base material has less influence on the mechanical properties of the base material, and especially has the effect of improving the mechanical properties of the long-term base material. The adhesive force of the paint is basically 0 level, and the hardness is basically 2H. The penetration height ratio is below 60%, preferably 25.28%, and the impermeability is good.
TABLE 1
FIG. 1 shows the appearance of the coating film of the example 1 on a cement mortar test block, and shows that the coating film has good state and no defects such as cracking.
FIG. 2 is a graph showing the results of static contact angle measurements of the surface of a blank cement coupon and a cement coupon coated with a water-resistant coating of the present invention. Wherein, (a) is the static contact angle of the cement paste without the waterproof material; (b) A cement paste static contact angle for coating the waterproofing material of example 1; (c) A cement paste static contact angle for coating the waterproofing material of example 2; (d) A cement paste static contact angle for coating the waterproofing material of example 3; (e) The cement paste used to coat the waterproofing material of example 4 had a static contact angle. It can be seen that the contact angle of the surface of the test block coated with the waterproof material is obviously increased compared with that of a blank group, which indicates that the hydrophobicity of the surface of the substrate is obviously improved.
FIG. 3 is an enlarged view of the XRD pattern characteristic of a blank cement test block and the hydration product of a cement test block coated with the waterproof coating of the present invention, and the fingerprint area of the characteristic hydration product; wherein (a) the XRD pattern is characterized by the hydration products of blank cement test blocks and cement test blocks coated with the waterproof coating material of the invention; (b) ettringite XRD enlarged pattern; (c) XRD magnification of dibasic calcium phosphate dihydrate. Compared with a blank group, the content of ettringite and calcium hydrophosphate in the net pulp test block hydration product coated with the waterproof coating disclosed by the invention is obviously increased, and the pores can be effectively plugged due to the generation of crystalline substances, so that the waterproof effect is achieved.
FIG. 4 is a cross-sectional water penetration profile of a blank and a coated waterproof coating substrate after a permeation resistance test is completed; wherein, (a) the water seepage condition of the profile of the base material after the anti-seepage test of the non-coated waterproof coating; (b) Coating example 3 water penetration profile of the substrate after the water-resistant coating permeation resistance test. The water seepage condition of the section of the base material coated with the waterproof coating is obviously better than that of a blank sample not coated with the waterproof coating, and the waterproof coating has excellent waterproof effect.
The invention provides a concrete self-cleaning organic-inorganic hybrid waterproof paint formula and a preparation thought and method thereof, and particularly discloses a homogeneous compound, a preparation method and a plurality of ways for realizing the technical scheme, wherein the above description is only a preferred embodiment of the invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be comprehended within the scope of the present invention. The components not explicitly described in this embodiment can be implemented by using the prior art.