CN115785760A - Coating for improving anti-carbonization performance of concrete and preparation method and application thereof - Google Patents
Coating for improving anti-carbonization performance of concrete and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a coating for improving the anti-carbonization performance of concrete and a preparation method and application thereof, belonging to the technical field of concrete. The paint comprises the following components in percentage by mass: 55-82% of aqueous epoxy resin emulsion and modified nano SiO 2 5 to 20 percent of polyethylene glycol, 2 to 5 percent of sodium xylene sulfonate, 5 to 10 percent of diacetone alcohol, 1 to 3 percent of polyether modified organic silicon defoamer, 0.1 to 0.3 percent of propylene glycol butyl ether and 3 to 7 percent of propylene glycol butyl ether; according to the invention, hydrophilic groups are introduced into the molecular chain of the epoxy resin, so that the obtained waterborne epoxy resin emulsion is easily dissolved in water, the dispersibility is enhanced, the viscosity of the solution is reduced, and the fluidity is enhanced; the invention is to nano SiO 2 The modified treatment is carried out to enhance the dispersibility of the paint, which is beneficial to reducing the porosity of the polymer paint and further improving the compactness of the coating structure, thereby reducing water and CO in the air 2 The anti-carbonization capability of the concrete is improved.
Description
Technical Field
The invention belongs to the technical field of concrete, and particularly relates to a coating for improving the anti-carbonization performance of concrete, and a preparation method and application thereof.
Background
Carbonization of concrete means that CO contained in the air 2 The concrete continuously enters the interior of the concrete through the pores on the surface of the concrete and reacts with hydrates in the concrete to generate carbonate and water, which leads to the reduction of the alkalinity of the concrete. Concrete buildings inevitably come into contact with the external environment during long-term use, and are easily corroded by various corrosive media in the atmosphere, wherein CO 2 As an acid gas, the corrosion action on concrete easily causes the concrete to be carbonized; the carbonization of the concrete can not only cause the reduction of the strength of the concrete and the bearing capacity of the bridge, but also cause the concrete to generate certain micro cracks due to the contraction of the concrete, thereby providing a more convenient channel for the erosion of harmful substances, further accelerating the deterioration of the performance of the concrete, causing the corrosion of reinforcing steel bars, shortening the service life of buildings such as the bridge and the highway, and even causing safety accidents. Meanwhile, the alkali-activated concrete not only needs to consume a large amount of OH in the polymerization reaction process - And no polymers are formed in the resulting polymerAnd substances resistant to carbonization, which leads to serious shortage of the carbonization resistance of alkali-activated concrete. Because the air contains a certain concentration of CO 2 ，CO 2 Can enter the inside of the alkali-activated concrete through diffusion, dissolve in the pore solution and form H 2 CO 3 。H 2 CO 3 Released H + With OH in the pore solution - Reaction, resulting in a decrease in the pH of the pore solution. The reduction of pH leads to the damage of a steel bar protective film in concrete, accelerates the corrosion of steel bars, causes the reduction of bearing capacity and seriously influences the durability of alkali-activated concrete.
On the other hand, the method adopted for acceptance of construction projects is mainly to detect the mechanical property of the concrete, namely the strength of the concrete after the corresponding age is measured; the resilience method is the most convenient strength detection method without damaging the internal structure of the concrete at present. After the resilience value is obtained through resilience, the carbonization depth of the concrete is required to be corrected, the structural strength often reaches the design requirement in the actual operation process, but the early carbonization depth value caused by the addition of the mineral admixture is large, the resilience strength cannot reach the design requirement after correction, and the difference between the structural strength and the resilience strength is large; therefore, concrete carbonization becomes a non-negligible factor affecting the accuracy of structure acceptance; in other words, the improvement of the anti-carbonization capability of the concrete is beneficial to improving the accuracy of acceptance of the concrete structure.
Therefore, the concrete carbonization not only influences the durability of the concrete, but also influences the accuracy of acceptance of the concrete structure; therefore, how to improve the anti-carbonization capability of concrete becomes a technical problem to be solved urgently. The method for improving the anti-carbonization capability of concrete in the prior art mainly comprises two methods: firstly, an additive is added in the process of preparing concrete so as to improve the anti-carbonization capability of the concrete; secondly, coating with film forming performance is sprayed on the surface of the concrete. For example, chinese patent CN113896452A discloses an admixture for improving the anti-carbonization ability of concrete, and a preparation method and an application thereof, which comprises the following components in parts by weight: 8-12 parts of mineral fine powder, 3-5 parts of silica fume, 10-15 parts of metakaolin, 3-5 parts of methyl silicate, 2-3 parts of expanding agent, 5-8 parts of superplasticizer and 6-12 parts of self-healing expansion fiber anti-cracking waterproof agent. The result shows that the additive provided by the invention can reduce the porosity in concrete by more than 50%, and effectively reduce the number of capillary pores and macropores; the prepared concrete can improve the strength by 70 percent in 3 days, reach the original strength of 28 days in 7 days, and improve the strength by about 20 percent in 28 days; the energy spectrum analysis of the concrete before and after carbonization shows that the carbon content in the concrete is lower even after carbonization, which indicates that the admixture has good carbonization resistance. For example, chinese patent CN102617184A discloses a concrete carbonation inhibitor, which mainly comprises a water-soluble high molecular polymer polyvinyl alcohol (PVA) solution and an acrylate emulsion, which are easy to form a film, and the polyvinyl alcohol and acrylate composite film has good gas barrier property, tolerance and aging resistance, and can effectively prevent gas and moisture from entering the interior of the concrete, improve the carbonation resistance of the concrete, and simultaneously prevent other corrosive media from entering the concrete, thereby improving the durability of the concrete. However, the above-mentioned carbonation suppressing agents have a limited effect of enhancing the carbonation resistance of concrete.
Disclosure of Invention
Aiming at the defects of the prior art, one of the purposes of the invention is to provide the coating for improving the anti-carbonization performance of the concrete, which can effectively improve the compactness of a coating structure, reduce the carbonization depth of the surface of the concrete and avoid the loss of alkaline substances; the problems that the alkalinity of the carbonized concrete is reduced, the protective effect of the concrete on the steel bars is weakened, and the overall strength and the comprehensive performance of the reinforced concrete structure are reduced are solved, and the durability of the reinforced concrete structure is improved.
In order to achieve the purpose, the specific technical scheme of the invention is as follows:
the coating for improving the anti-carbonization performance of concrete comprises the following components in percentage by mass: 55-82% of aqueous epoxy resin emulsion and modified nano SiO 2 5-20 percent of polyethylene glycol, 2-5 percent of sodium xylene sulfonate, 5-10 percent of sodium xylene sulfonate, 1-3 percent of diacetone alcohol, 0.1-0.3 percent of polyether modified organic silicon defoamer and 3-7 percent of propylene glycol butyl ether;
the modified nano SiO 2 System of (1)The preparation method comprises the following steps:
s1, firstly, preparing nano SiO 2 Pouring the mixture into a ball mill for grinding to obtain nano SiO with the particle size of 20-30 nm 2 Then grinding the nano SiO 2 Dissolving in an aqueous solution of absolute ethyl alcohol, and dispersing to obtain a mixed solution a; uniformly mixing glacial acetic acid, a silane coupling agent, polyoxyethylene ether and p-toluenesulfonic acid to obtain a mixed solution b;
s2, mixing the mixed solution a and the mixed solution b to obtain a mixed solution, heating to 70-80 ℃, stirring for 10-30 min, transferring to room temperature, and continuously stirring for 0.5-1 h; finally, the modified nano SiO is obtained after centrifugation, washing and drying 2 。
The principle of the invention is as follows: the epoxy resin coating can generate micropores in the film forming process, so that the compact effect of the film structure is relatively poor, and the nano SiO is added 2 The generated micropores can be filled, thereby reducing the porosity; but nano SiO 2 It is difficult to wet and uniformly disperse in the epoxy resin, and the filling effect is influenced. The invention firstly aligns the nano SiO 2 Grinding is carried out, and the purpose of grinding is to enable the nano SiO 2 Uniformly dispersed and prevented from nano SiO 2 Producing agglomeration; then under the action of glacial acetic acid and p-toluenesulfonic acid, the nanometer SiO is treated by using a silane coupling agent and a nonionic surfactant polyoxyethylene ether 2 Carrying out modification treatment, wherein glacial acetic acid is used for providing an acidic environment for the reaction of the silane coupling agent, and p-toluenesulfonic acid is used as a catalyst; by adopting the technical scheme, the nano SiO 2 The surface is coated by hydrophobic alkyl groups, which is beneficial to nano SiO 2 The coating is uniformly dispersed in the coating, so that the porosity of the coating after film formation is greatly reduced, and the compactness of a coating film structure is improved; meanwhile, the contact area of the liquid drop and the substrate is reduced, the contact angle is increased, and the hydrophobic capacity of the coating is enhanced, so that water and CO in the air are reduced 2 The anti-carbonization capability of the concrete is improved.
In the coating of the invention, polyethylene glycol is used as a dispersant for dispersing nano SiO 2 The binding force between particles prevents the modification of the nano SiO 2 ParticlesAgglomeration is generated, so that the whole system is in a stable state; sodium xylene sulfonate is used as a wetting agent and is used for reducing the surface tension of the coating so that the coating forms a continuous film; diacetone alcohol is used as a leveling agent to increase the fluidity of the coating, promote the water-based coating to form a flat, smooth and uniform coating film in the drying and film-forming process, and increase the coverage and abrasion resistance; the propylene glycol butyl ether is used as a film forming agent for reducing the lowest film forming temperature of the waterborne epoxy resin emulsion, and is beneficial to forming a continuous film by the coating.
Preferably, the coating comprises the following components in percentage by mass: 69.3 percent of aqueous epoxy resin emulsion and modified nano SiO 2 15 percent of polyethylene glycol, 3 percent of sodium xylene sulfonate, 7.5 percent of sodium xylene sulfonate, 1.5 percent of diacetone alcohol, 0.2 percent of polyether modified organic silicon defoamer and 3.5 percent of propylene glycol butyl ether.
Preferably, in step S1, the nano SiO in the mixed solution a 2 The mass ratio of the absolute ethyl alcohol to the deionized water is (20-40) to (35-50) to (10-25); the mass ratio of the glacial acetic acid, the silane coupling agent, the polyoxyethylene ether and the p-toluenesulfonic acid in the mixed solution b is (3-10): 10-20): 5-9): 0.1-0.5.
Preferably, in step S2, the nano SiO in the mixed solution 2 The mass ratio of the silane coupling agent to the silane coupling agent is 1 (5-8).
Preferably, the preparation method of the aqueous epoxy resin emulsion comprises the following steps:
p1, under the protection of inert gas, mixing epoxy resin with n-octane alcohol, and stirring for 2-4 h at 60-70 ℃ under the catalytic action of trifluoromethanesulfonic acid to obtain a water-based epoxy resin solution;
and P2, adding sodium dodecyl sulfate into the aqueous epoxy resin solution obtained in the step P1, heating to 80-90 ℃, starting stirring, dropwise adding deionized water while stirring, carrying out emulsion polymerization reaction, reacting for 0.5-1.5 h, then adding allyloxy hydroxypropyl sodium sulfonate, continuing to react for 2-4 h, cooling to room temperature after the reaction is finished, adding glacial acetic acid to adjust the pH value of the solution to 6.0, and finally adding deionized water to dilute until the solid content is 45-55% to obtain the aqueous epoxy resin emulsion.
The preparation mechanism of the waterborne epoxy resin emulsion of the invention is as follows: under the catalytic action of trifluoromethanesulfonic acid, dissolving epoxy resin in n-octanol to obtain a water-based epoxy resin solution; adding emulsifier sodium dodecyl sulfate and allyloxy hydroxypropyl sodium sulfonate into the aqueous epoxy resin solution, slowly dripping water under the stirring action, wherein the initial stage of the mixed system is in a water-in-oil (W/O) state, the viscosity of the emulsified system is higher, and the viscosity of the system is reduced along with the increase of the stirring action and the dripping amount; when the viscosity is reduced to stir with liquid flow sound, the mixed system is changed from a water-in-oil (W/O) state to an oil-in-water (O/W) state, namely, a stable and homogeneous aqueous epoxy resin emulsion is formed. Sodium dodecyl sulfate is used as an emulsifier, and allyloxy hydroxypropyl sodium sulfonate has the functions of emulsification and dispersion and can participate in polymerization, so that an epoxy resin system forms a good controllable molecular chain segment; by adopting the technical scheme, hydrophilic groups can be introduced into the molecular chain of the epoxy resin, so that the obtained waterborne epoxy resin emulsion is easy to dissolve in water, the dispersibility is enhanced, the viscosity of the solution is reduced, and the fluidity is enhanced; and meanwhile, the adhesive force between the epoxy resin and the concrete can be enhanced, so that the coating and the concrete are tightly connected. In addition, the water-based epoxy resin emulsion takes water as a solvent in the using process, and an organic solvent is not needed to be used for dissolving the epoxy resin, so that the emission of volatile organic compounds and the pollution to the environment are greatly reduced.
Preferably, in the step P1, the volume ratio of the epoxy resin, the n-octane alcohol and the trifluoromethanesulfonic acid is (25-35): 3-7): 1.
Preferably, in the step P2, the mass-to-volume ratio of the aqueous epoxy resin solution, the sodium dodecyl sulfate, the deionized water and the allyloxy hydroxypropyl sodium sulfonate is 100mL, (7-9) g, (70-80) mL, (10-20) mL.
The invention also aims to provide a preparation method of the coating for improving the anti-carbonization performance of concrete, which comprises the following steps: weighing the components according to the mass percentage, and then adding modified nano SiO into the aqueous epoxy resin emulsion 2 Ultrasonic dispersing for 5-15 min, and finally adding the polyethylene glycol and xylene sulfonic acidAnd (3) uniformly stirring sodium salt, diacetone alcohol, a polyether modified organic silicon defoamer and propylene glycol butyl ether to obtain the coating.
The invention also aims to provide the application of the coating for improving the anti-carbonization performance of the concrete in the concrete, wherein the coating is sprayed on the surface of the concrete, and the spraying amount is 0.1-0.4 kg/m 2 。
Preferably, before the coating is sprayed, the concrete is dried for 40-50 h at 60-70 ℃, and then the surface of the concrete is polished and cleaned by using sand paper and wet cloth, so that the firm bonding between the coating and the concrete is ensured.
Preferably, the spraying pressure is 0.2-0.4 MPa, and the spraying speed is 100-150 mL/min.
Compared with the prior art, the invention has the advantages that:
(1) Under the action of glacial acetic acid and p-toluenesulfonic acid, the invention firstly utilizes the silane coupling agent and the nonionic surfactant polyoxyethylene ether to react with the nano SiO 2 Modifying, wherein glacial acetic acid provides an acid environment for the reaction of the silane coupling agent, p-toluenesulfonic acid is used as a catalyst, and the technical scheme is adopted to ensure that the nano SiO is prepared 2 The surface is coated by hydrophobic alkyl groups, which is beneficial to nano SiO 2 The coating is uniformly dispersed in the coating, so that the porosity of the coating after film formation is greatly reduced, and the compactness of a coating structure is improved; meanwhile, the contact area of the liquid drop and the substrate is reduced, the contact angle is increased, and the hydrophobic capacity of the coating is enhanced, so that water and CO in the air are reduced 2 The anti-carbonization capability of the concrete is improved.
(2) According to the invention, hydrophilic groups are introduced into the molecular chain of the epoxy resin, so that the obtained waterborne epoxy resin emulsion is easily dissolved in water, the dispersibility is enhanced, the viscosity of the solution is reduced, and the fluidity is enhanced; and meanwhile, the adhesive force between the epoxy resin and the concrete can be enhanced, so that the coating and the concrete are tightly connected.
(3) Compared with the traditional coating, the coating provided by the invention can effectively reduce the microscopic defects in the coating, the compactness of the coating is enhanced, and the anti-carbonization capability of the concrete can be effectively improved by spraying the coating on the surface of the concrete.
Detailed Description
The technical solutions of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the following examples and comparative examples, nano SiO 2 Is white fluffy powder with the grain diameter of 20-30 nm and the volume density of 60kg/m 3 (ii) a The epoxy resin is epoxy resin F51; the silane coupling agent is a silane coupling agent KH-570; the polyethylene glycol is polyethylene glycol 200; the polyether modified organic silicon defoamer is a TEGO901W defoamer;
the invention discloses a preferable preparation method of a coating for improving the anti-carbonization performance of concrete, which comprises the following steps: weighing the components according to the mass percent, and adding modified nano SiO into the aqueous epoxy resin emulsion 2 And ultrasonically dispersing for 5-15 min, finally adding the polyethylene glycol, sodium xylene sulfonate, diacetone alcohol, the polyether modified organic silicon defoamer and propylene glycol butyl ether, and uniformly stirring to obtain the coating.
Example 1
The embodiment provides a coating for improving the anti-carbonization performance of concrete, which comprises the following components in percentage by mass: 78.8 percent of waterborne epoxy resin emulsion and modified nano SiO 2 5 percent of polyethylene glycol, 5 percent of sodium xylene sulfonate, 6 percent of diacetone alcohol, 1.5 percent of polyether modified organic silicon defoamer, 0.2 percent of propylene glycol butyl ether and 3.5 percent of sodium xylene sulfonate;
wherein, the modified nano SiO 2 The preparation method comprises the following steps:
s1, preparing a mixed solution a: firstly, nano SiO is added 2 Pouring into a ball mill to grind for 20min to obtain the nano SiO with the particle size of 20-30 nm 2 (ii) a Then grinding the nano SiO 2 And the absolute ethyl alcohol and the deionized water are poured into a beaker according to the mass ratio of 25 to 40 for mixing, and then the beaker is placed into an ultrasonic dispersion instrument, wherein the mass ratio of the absolute ethyl alcohol to the deionized water is as follows2×10 4 Hz～10 9 Performing ultrasonic dispersion for 30min under the power of Hz sound waves to obtain a mixed solution a;
preparing a glacial acetic acid solution: 25g of glacial acetic acid powder was dissolved in 25mL of distilled water, then the pH was adjusted to 3.0 (potentiometrically indicated) with 2mol/L hydrochloric acid solution and finally diluted to 100mL with distilled water to give a glacial acetic acid solution.
Preparing a mixed solution b: mixing the obtained glacial acetic acid solution with a silane coupling agent, polyoxyethylene ether and p-toluenesulfonic acid according to a mass ratio of 6;
s2, mixing the mixed solution a and the mixed solution b to obtain a mixed solution (nano SiO in the mixed solution) 2 The mass ratio of the silane coupling agent to the silane coupling agent is 1), heating the mixed solution to 75 ℃, stirring for 15min, transferring to room temperature, and then continuing stirring for 45min by using a magnetic stirrer; then centrifuging to obtain nano particles, cleaning the nano particles by using deionized water and absolute ethyl alcohol to remove the silane coupling agent adsorbed on the surfaces of the nano particles, and finally drying in vacuum for 6 hours to obtain modified nano SiO 2 。
The preparation method of the waterborne epoxy resin emulsion comprises the following steps:
p1, adding 300mL of epoxy resin F51, 50mL of n-octanol and 10mL of trifluoromethanesulfonic acid into a four-mouth bottle, then introducing nitrogen, and avoiding CO in the air under the protection of nitrogen 2 Taking part in chemical reaction, heating to 65 ℃ by a heating device, and stirring for 200min at 2000r/min under the catalytic action of trifluoromethanesulfonic acid to obtain a water-soluble aqueous epoxy resin solution;
p2, adding 100mL of the aqueous epoxy resin solution obtained in the step P1 and 8g of sodium dodecyl sulfate into a four-mouth bottle, heating to 85 ℃, stirring at the rotating speed of 2000r/min, dropwise adding deionized water while stirring to enable the solution to have an emulsion polymerization reaction, wherein the process lasts for 1h, and 75mL of deionized water is totally dropwise added; then adding 16mL of allyloxy hydroxypropyl sodium sulfonate for reaction for 3h, cooling to room temperature after the reaction is finished, adding glacial acetic acid to adjust the pH value of the solution to 6.0, and finally adding 900mL of deionized water for dilution to obtain the aqueous epoxy resin emulsion with the solid content of 50%.
Example 2
The coating for improving the anti-carbonization performance of the concrete comprises the following components in percentage by mass: 71.8 percent of waterborne epoxy resin emulsion and modified nano SiO 2 10 percent of polyethylene glycol, 3 percent of sodium xylene sulfonate, 10 percent of diacetone alcohol, 1.5 percent of diacetone alcohol, 0.2 percent of polyether modified organic silicon defoamer and 3.5 percent of propylene glycol butyl ether;
wherein, the modified nano SiO 2 The preparation method comprises the following steps:
s1, preparing a mixed solution a: firstly, nano SiO is added 2 Pouring the mixture into a ball mill to grind for 20min to obtain nano SiO with the particle size of 20-30 nm 2 (ii) a Then grinding the nano SiO 2 And the absolute ethyl alcohol and the deionized water are poured into a beaker according to the mass ratio of 20 4 Hz～10 9 Performing ultrasonic dispersion for 30min under the power of Hz sound waves to obtain a mixed solution a;
preparing a glacial acetic acid solution: 25g of glacial acetic acid powder was dissolved in 25mL of distilled water, then the pH was adjusted to 3.0 (potentiometrically indicated) with 2mol/L hydrochloric acid solution and finally diluted to 100mL with distilled water to give a glacial acetic acid solution.
Preparing a mixed solution b: mixing the obtained glacial acetic acid solution with a silane coupling agent, polyoxyethylene ether and p-toluenesulfonic acid according to a mass ratio of 3;
s2, mixing the mixed solution a and the mixed solution b to obtain a mixed solution (nano SiO in the mixed solution) 2 The mass ratio of the silane coupling agent to the silane coupling agent is 1), heating the mixed solution to 70 ℃, stirring for 10min, transferring to room temperature, and then continuing stirring for 30min by using a magnetic stirrer; then centrifuging to obtain nano particles, cleaning the nano particles by using deionized water and absolute ethyl alcohol to remove a silane coupling agent adsorbed on the surfaces of the nano particles, and finally drying in vacuum for 6 hours to obtain modified nano SiO 2 。
The preparation method of the water-based epoxy resin emulsion comprises the following steps:
p1, adding 350mL of epoxy resin F51, 30mL of n-octanol and 10mL of trifluoromethanesulfonic acid into a four-mouth bottle, then introducing nitrogen, and avoiding CO in air under the protection of nitrogen 2 Taking part in chemical reaction, heating to 60 ℃ by a heating device, and stirring for 120min at 2000r/min under the catalytic action of trifluoromethanesulfonic acid to obtain a water-soluble aqueous epoxy resin solution;
p2, adding 100mL of the aqueous epoxy resin solution obtained in the step P1 and 7g of sodium dodecyl sulfate into a four-mouth bottle, heating to 80 ℃, stirring at the rotating speed of 2000r/min, dropwise adding deionized water while stirring to enable the solution to have an emulsion polymerization reaction, wherein the process lasts for 0.5h, and 70mL of deionized water is totally dropwise added; then adding 10mL of allyloxy hydroxypropyl sodium sulfonate for reaction for 4h, cooling to room temperature after the reaction is finished, adding glacial acetic acid to adjust the pH value of the solution to 6.0, and finally adding deionized water for dilution until the solid content is 50% to obtain the water-based epoxy resin emulsion.
Example 3
The embodiment 3 is basically the same as the embodiment 1, except that the coating for improving the carbonization resistance of the concrete comprises the following components in percentage by mass: 69.3 percent of aqueous epoxy resin emulsion and modified nano SiO 2 15 percent of polyethylene glycol, 3 percent of sodium xylene sulfonate, 7.5 percent of sodium xylene sulfonate, 1.5 percent of diacetone alcohol, 0.2 percent of polyether modified organic silicon defoamer and 3.5 percent of propylene glycol butyl ether.
Example 4
Example 4 is substantially the same as example 1, except that the coating for improving the carbonization resistance of concrete in the embodiment comprises the following components in percentage by mass: 62.8 percent of waterborne epoxy resin emulsion and modified nano SiO 2 20 percent of polyethylene glycol 3 percent, sodium xylene sulfonate 6 percent, diacetone alcohol 3 percent, polyether modified organic silicon defoamer 0.2 percent and propylene glycol butyl ether 5 percent.
Comparative example 1
Comparative example 1 is substantially the same as example 3 except that the comparative example employs unmodified nano-SiO 2 Substitute modified nano SiO 2 The amount used remains the same.
Comparative example 2
Comparative example 2 is essentially the same as example 3 except that the acrylic resin is used in place of the aqueous epoxy resin emulsion in the present comparative example and the amount is maintained.
Comparative example 3
Comparative example 3 is substantially the same as example 3 except that the coating for improving the concrete carbonization resistance of the comparative example comprises the following components in percentage by mass: 69.3 percent of epoxy resin F51 and modified nano SiO 2 15 percent of polyethylene glycol 3 percent, 7.5 percent of sodium xylene sulfonate, 1.5 percent of diacetone alcohol, 0.2 percent of polyether modified organic silicon defoamer and 3.5 percent of propylene glycol butyl ether;
that is, this comparative example uses an undissolved, unemulsified epoxy resin F51 instead of the aqueous epoxy resin emulsion, as compared with example 1.
Test examples
The concrete surface is sprayed with the coatings of the examples and the comparative examples, and the concrete steps are as follows:
1) Manufacturing a cube concrete test block of 100 x 100mm according to the concrete mixing proportion in table 1, placing the test block in a 60 ℃ oven for drying for 48 hours after removing the mold, and then polishing and cleaning the surface of the test block by using abrasive paper and wet cloth;
2) The coatings of the examples and the comparative examples are added into a high atomization spray gun, the pressure of the spray gun is set to be 0.2-0.4 MPa, and the spraying speed is set to be 100-150 mL/min; the side surface of the cubic concrete test block is aligned to be evenly sprayed, and the spraying amount is 0.1-0.4 kg/m 2 (ii) a Then, the sprayed test block is placed in a 60 ℃ oven to be dried for 24 hours, and then is placed in a standard curing room (the temperature is 20 +/-2 ℃, and the relative humidity is 95%) to be cured for 28 days; and the concrete test block which is not sprayed with the coating is taken as a blank control group.
3) Carrying out accelerated concrete carbonization test according to GB/T50082-2009 Standard test method for testing long-term performance and durability of ordinary concrete, wherein the carbonization conditions are as follows: CO 2 2 The concentration is (20 +/-3)%, the temperature is (20 +/-2) ° C, and the humidity is (70 +/-5)%; the carbonization depth of test blocks with the carbonization age of 3 days, 7 days, 14 days and 28 days is measured, and the test results are shown in the table2。
Table 1 shows the concrete mix ratio (kg/m) 3 )
| Cement | Fly ash | Mineral powder | Sand | Crushing stone | Water (I) | Water reducing agent/%) |
| 280 | 70 | 60 | 785 | 1012 | 170 | 2.1 |
Wherein the cement is conch P.O 42.5; the fly ash is II-grade fly ash; the mineral powder is S95 grade mineral powder; the sand is natural river sand, and the fineness modulus is 2.6; the crushed stone is 5-20 mm continuous graded crushed stone; the water reducing agent is a polycarboxylic acid high-performance water reducing agent, the solid content is 18 percent, and the water reducing rate is 23.5 percent.
TABLE 2 results of carbonation depth test of concrete surface
As can be seen from the data in Table 2, the carbonization depth of the concrete surface coated with the coating of the present invention was significantly reduced compared to the blank group, indicating that the coating of the present invention can effectively improve the carbonization resistance of the concrete surface. As can be seen from comparison of examples 1 to 4, with modification of the nano SiO 2 The content is increased, the carbonization depth of the concrete in 28d age is firstly reduced and then increased, when the nano SiO is modified 2 The content of (A) is 15%, the anti-carbonization ability of the coating is optimal.
By comparing example 3 with comparative example 1, it can be seen that nano SiO 2 After modification, the carbonization depth is obviously reduced, which shows that the nano SiO is treated 2 The modification can improve the anti-carbonization performance of the concrete surface, mainly because of the modified nano SiO 2 The dispersibility is enhanced, the porosity of the coating is reduced, the compactness of a coating structure is improved, and the carbonization resistance of the concrete surface is improved. By comparing example 3 with comparative example 2, it can be seen that replacing the epoxy resin with an acrylic resin reduces the resistance of the coating to CO 2 Resulting in a decrease in the anti-carbonation capacity of the concrete.
By comparing example 3 with comparative example 3, it can be found that the depth of carbonation of concrete is remarkably increased by using the undissolved, unemulsified epoxy resin F51; the main reason is that the epoxy resin F51 is not easily soluble in water, has poor dispersibility and high viscosity, and cannot form a dense film. The aqueous epoxy resin emulsion obtained after the epoxy resin is modified is easy to dissolve in water, the dispersibility is enhanced, the viscosity of the solution is reduced, and the fluidity is enhanced; and meanwhile, the adhesive force between the epoxy resin and the concrete can be enhanced, so that the coating and the concrete are tightly connected.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (9)
1. The coating for improving the anti-carbonization performance of concrete is characterized by comprising the following components in percentage by mass: 55-82% of waterborne epoxy resin emulsion and modified nano SiO 2 5-20 percent of polyethylene glycol, 2-5 percent of sodium xylene sulfonate, 5-10 percent of sodium xylene sulfonate, 1-3 percent of diacetone alcohol, 0.1-0.3 percent of polyether modified organic silicon defoamer and 3-7 percent of propylene glycol butyl ether;
the modified nano SiO 2 The preparation method comprises the following steps:
s1, preparing nano SiO 2 Dissolving in an aqueous solution of absolute ethyl alcohol, and dispersing to obtain a mixed solution a; uniformly mixing glacial acetic acid, a silane coupling agent, polyoxyethylene ether and p-toluenesulfonic acid to obtain a mixed solution b;
s2, mixing the mixed solution a and the mixed solution b to obtain a mixed solution, heating to 70-80 ℃, stirring for 10-30 min, transferring to room temperature, and continuously stirring for 0.5-1 h; finally, the modified nano SiO is obtained after centrifugation, washing and drying 2 。
2. The coating for improving the carbonization resistance of concrete according to claim 1, is characterized by comprising the following components in percentage by mass: 69.3 percent of waterborne epoxy resin emulsion and modified nano SiO 2 15 percent of polyethylene glycol, 3 percent of sodium xylene sulfonate, 7.5 percent of sodium xylene sulfonate, 1.5 percent of diacetone alcohol, 0.2 percent of polyether modified organic silicon defoamer and 3.5 percent of propylene glycol butyl ether.
3. The coating for improving the carbonization resistance of concrete according to claim 1, wherein in step S1, the nano SiO in the mixed solution a 2 The mass ratio of the absolute ethyl alcohol to the deionized water is (20-40) to (35-50) to (10-25); the mass ratio of the glacial acetic acid, the silane coupling agent, the polyoxyethylene ether and the p-toluenesulfonic acid in the mixed solution b is (3-10) to (10-20) to (5-9) to (0.1-0.5).
4. The coating for improving the carbonization resistance of concrete according to claim 1, wherein in step S2, the mixture is mixedNano SiO in the solution 2 The mass ratio of the silane coupling agent to the silane coupling agent is 1 (5-8).
5. The coating for improving the carbonization resistance of concrete according to claim 1, wherein the preparation method of the water-based epoxy resin emulsion comprises the following steps:
p1, under the protection of inert gas, mixing epoxy resin with n-octane alcohol, and stirring for 2-4 h at 60-70 ℃ under the catalytic action of trifluoromethanesulfonic acid to obtain a water-based epoxy resin solution;
and P2, adding sodium dodecyl sulfate into the aqueous epoxy resin solution obtained in the step P1, heating to 80-90 ℃, starting stirring, dropwise adding deionized water while stirring, carrying out emulsion polymerization reaction, reacting for 0.5-1.5 h, then adding allyloxy hydroxypropyl sodium sulfonate, continuing to react for 2-4 h, cooling to room temperature after the reaction is finished, adding glacial acetic acid to adjust the pH value of the solution to be neutral, and finally adding deionized water to dilute until the solid content is 45-55%, thus obtaining the aqueous epoxy resin emulsion.
6. The coating for improving the carbonization resistance of concrete according to claim 5, wherein in the step P1, the volume ratio of the epoxy resin to the n-octanol to the trifluoromethanesulfonic acid is (25-35): (3-7): 1.
7. The coating for improving the carbonization resistance of concrete according to claim 5, wherein in step P2, the mass-to-volume ratio of the aqueous epoxy resin solution, the sodium dodecyl sulfate, the deionized water and the sodium allyloxy hydroxypropyl sulfonate is 100mL, (7-9) g, (70-80) mL, (10-20) mL.
8. The preparation method of the coating for improving the carbonization resistance of concrete according to any one of claims 1 to 7, is characterized by comprising the following steps: weighing the components according to the mass percentage, and adding modified nano SiO into the aqueous epoxy resin emulsion 2 Ultrasonic dispersing for 5-15 min, and finally adding the polyethylene glycol, sodium xylene sulfonate and diacetoneAnd uniformly stirring the alcohol, the polyether modified organic silicon defoamer and the propylene glycol butyl ether to obtain the coating.
9. The use of a coating for improving the carbonation resistance of concrete according to any one of claims 1 to 7, wherein said coating is sprayed on the surface of the concrete in an amount of 0.1 to 0.4kg/m 2 。
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| CN116290888A (en) * | 2023-03-22 | 2023-06-23 | 兰州有色冶金设计研究院有限公司 | Structure and method for prolonging service life of reinforced concrete building |
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