Preparation method and use method of concrete surface retarder

Abstract

The invention discloses a preparation method and a use method of a concrete surface retarder. The preparation method comprises the following steps: adding xanthan gum into water until the xanthan gum is completely dissolved, adding sodium-based zeolite and strong-acid cation exchange resin, and ultrasonically dispersing uniformly to form an emulsion A; adding hydroxypropyl carrageenan into solvent water, stirring until the hydroxypropyl carrageenan is completely dissolved, adding oxalic acid and dilute sulphuric acid, and uniformly stirring to form a solution B; the emulsion A and the solution B form the concrete surface retarder, and the emulsion A and the solution B are independently stored before use; when the concrete surface retarder is used, the emulsion A and the solution B are sprayed on the surface of concrete twice. By adopting the concrete surface retarder disclosed by the invention, surface retarding of concrete can be effectively realized, the surface retarding etching depth can be effectively controlled, a sagging phenomenon is avoided, a good application effect of the concrete surface retarder is realized, and adverse effects of the concrete surface retarder on a concrete interface are avoided.

Description

Technical Field

[0001] The invention relates to the field of concrete admixtures, and in particular to a preparation method and a use method of a concrete surface retarder. Background Art

[0002] During the construction of concrete projects, due to the diversity of structures and the inconsistency of structural cross-sectional areas, multiple pourings are often required to form the concrete structure required by the design. This creates the problem of the joints between new and old concrete. In order to make the new and old concrete bond well together, the surface where the original concrete contacts the new concrete must be roughened, that is, the smooth surface of the solidified concrete is removed to expose the rough surface. The quality of the rough surface treatment of the concrete directly affects the bonding effect of the new and old concrete.

[0003] Concrete surface retarder can solve the problem of interface connection between new and old concrete. By coating the surface of the concrete to be roughened, after the concrete is cured and demoulded, roughening can be carried out by matching machinery or manual work, so that a rough concrete bonding interface can be effectively obtained. No filing, roughening or sandblasting is required, which not only ensures the bonding quality of the concrete interface, but also reduces the work intensity, improves the work efficiency, and plays a good role in reducing energy consumption, noise and dust pollution. However, the use of retarding components often causes problems such as sag of concrete slurry and surface collapse, and even affects the normal hardening of the internal concrete, leading to structural safety accidents. At the same time, with the increase of the amount of retarding components, the retarding time of concrete is gradually prolonged. Too few retarding components cannot meet the surface roughness requirements, and too many retarding components affect the normal hardening of the internal concrete. These are the problems that exist in the current surface retarding technology and need to be solved. Therefore, it is necessary to achieve the purpose of retarding the surface of concrete components and avoid the phenomenon of sag of the concrete surface retarder. It is a problem that needs to be solved to effectively achieve a better surface roughening effect and a suitable etching depth after flushing. Summary of the invention

[0004] In view of the problems existing in the above-mentioned background technology, the present invention provides a preparation method and use method of a concrete surface retarder. The prepared concrete surface retarder can effectively realize the surface retarding of concrete, and can effectively control the surface retarding etching depth and avoid sagging, thereby achieving a good application effect of the concrete surface retarder and avoiding its adverse effects on the concrete interface.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for preparing a concrete surface retarder comprises the following steps:

[0007] (1) After xanthan gum is added to water and completely dissolved, sodium-based zeolite and strongly acidic cation exchange resin are added and ultrasonically dispersed to form an emulsion A;

[0008] (2) adding hydroxypropyl carrageenan to solvent water and stirring until completely dissolved, then adding oxalic acid and dilute sulfuric acid and stirring evenly to form solution B;

[0009] (3) The emulsion A obtained in step (1) and the solution B obtained in step (2) constitute the concrete surface retarder, and the emulsion A and the solution B are stored separately before use.

[0010] Furthermore, the mass fractions of each raw material component in step (1) of the present invention are as follows:

[0011]

[0012] Furthermore, the ultrasonic dispersion in step (1) of the present invention is carried out at a wave frequency of not less than 60 Hz for 3 to 5 minutes, thereby achieving complete dispersion of the xanthan gum, sodium-based zeolite and strongly acidic cation exchange resin in water.

[0013] Furthermore, the strongly acidic cation exchange resin in step (1) of the present invention is selected from one of sulfonic acid polystyrene resin, chlorinated polyphenylene vinyl resin and chlorinated methyl acrylate.

[0014] Furthermore, the mass fractions of each raw material component in step (2) of the present invention are as follows:

[0015]

[0016] Furthermore, the temperature of the solvent water added in step (2) of the present invention is between 60° C. and 80° C. The temperature is controlled in this step to allow the hydroxypropyl carrageenan to dissolve quickly.

[0017] Furthermore, in the concrete surface retarder in step (3) of the present invention, the mass ratio of emulsion A to solution B is 1-2:3-5.

[0018] The present invention also provides a method for using the concrete surface retarder prepared above, comprising the following steps:

[0019] (1) Spray emulsion A evenly on the concrete surface through atomization equipment, and control the spraying amount to 0.1-0.2 kg / m 2 ;

[0020] (2) After spraying emulsion A, let it stand for 3 to 5 minutes, then immediately spray solution B at a spraying rate of 0.3 to 0.5 kg / m 2 .

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Xanthan gum, strong acid cation exchange resin, and sodium zeolite are used as calcium ion absorbers in the cement hydration process to achieve chelation, adsorption, and exchange of calcium ions, reduce the calcium ion concentration in the solution, and delay cement hydration. At the same time, in view of the limited adsorption of calcium ions by xanthan gum, strong acid cation exchange resin, sodium zeolite, etc., in order to avoid excessive adsorption saturation during use, resulting in the inability to further absorb calcium ions, thereby delaying the failure of cement hydration, a calcium ion precipitant mainly composed of hydroxypropyl carrageenan, oxalic acid, and dilute sulfuric acid is sprayed on them: through the chelation of carrageenan, an irreversible gel is formed to completely bind calcium ions; through oxalic acid and calcium ions, calcium oxalate precipitation is formed to bind calcium ions; through dilute sulfuric acid and calcium ions, calcium sulfate precipitation is formed to bind calcium ions, thereby realizing the consumption of calcium ions in the calcium ion adsorbent, ensuring the continuous adsorption of calcium ions by the calcium ion adsorbent, and playing a retarding effect. At the same time, in addition to being a calcium ion chelating agent, xanthan gum also retains water and increases viscosity, avoiding surface water exudation and segregation, and plays an anti-sagging role in the retarding process; carrageenan itself also has the same water-retaining and viscosity-increasing properties as xanthan gum. At the same time, when it chelates with calcium ions to form an irreversible gel, it has extremely strong binding properties on calcium ions and also has extremely strong surface anti-sagging properties; secondly, the calcium oxalate and calcium sulfate generated by the reaction are both effective retarding components, which can inhibit further hydration of cement by attaching to hydration products, continue to play a surface retarding role, and can promote surface peeling.

[0023] When the concrete surface retarder is used in the present invention, the calcium ions are absorbed in the first time and precipitated in the second time through the synergistic effect of two sprayings, thereby achieving complete binding of the calcium ions, completely delaying the formation of calcium silicate and normal coagulation of cement in the cement hydration process on the surface, and achieving the purpose of surface retarding. Furthermore, by controlling the spraying amount, the depth of retarding is effectively controlled, achieving a better surface retarding effect. DETAILED DESCRIPTION

[0024] The present invention will be further described and illustrated below in conjunction with specific embodiments, but the examples are only for helping to understand the invention, and the protection scope of the present invention is not limited thereto.

[0025] Example 1

[0026] A method for preparing a concrete surface retarder comprises the following steps:

[0027] (1) 0.5 parts of xanthan gum was added to 100 parts of water until it was completely dissolved, and then 5 parts of sodium zeolite and 5 parts of chloromethyl acrylate were added, and ultrasonic dispersion was performed at a frequency of 60 Hz for 5 minutes to uniformly form an emulsion A;

[0028] (2) Add 1 part of hydroxypropyl carrageenan to 100 parts of water at 80° C. and stir until completely dissolved, then add 10 parts of oxalic acid and 5 parts of H2SO4 (added in the form of dilute sulfuric acid, with the water content controlled at 10 parts and the total amount of H2SO4 controlled at 5 parts), and stir evenly to form solution B;

[0029] (3) The emulsion A obtained in step (1) and the solution B obtained in step (2) constitute the concrete surface retarder, and the emulsion A and the solution B are stored separately before use.

[0030] The spraying method is:

[0031] Spray emulsion A evenly on the concrete surface through atomization equipment, and control the spraying amount at 0.15kg / m 2 ;

[0032] After spraying emulsion A, let it stand for 4 minutes, then spray solution B immediately, with a spraying amount of 0.4kg / m 2 .

[0033] Example 2

[0034] A method for preparing a concrete surface retarder comprises the following steps:

[0035] (1) Add 1 part of xanthan gum to 100 parts of water until it is completely dissolved, then add 3 parts of sodium zeolite and 10 parts of chlorinated polyphenylene vinyl resin, and disperse them ultrasonically at a frequency of 80 Hz for 3 minutes to uniformly form an emulsion A;

[0036] (2) Add 2 parts of hydroxypropyl carrageenan to 100 parts of water at 60° C. and stir until completely dissolved, then add 20 parts of oxalic acid and 3 parts of H2SO4 (added in the form of dilute sulfuric acid, with the water content controlled at 20 parts and the total amount of H2SO4 controlled at 3 parts), and stir evenly to form solution B;

[0037] (3) The emulsion A obtained in step (1) and the solution B obtained in step (2) constitute the concrete surface retarder, and the emulsion A and the solution B are stored separately before use.

[0038] The spraying method is:

[0039] Spray emulsion A evenly on the concrete surface through atomization equipment, and control the spraying amount at 0.15kg / m 2 ;

[0040] After spraying emulsion A, let it stand for 4 minutes, then spray solution B immediately, with a spraying amount of 0.4kg / m 2 .

[0041] Example 3

[0042] A method for preparing a concrete surface retarder comprises the following steps:

[0043] (1) 0.8 parts of xanthan gum was added to 100 parts of water until it was completely dissolved, and then 4 parts of sodium zeolite and 8 parts of sulfonated styrene resin were added, and ultrasonic dispersion was performed at a frequency of 70 Hz for 4 minutes to uniformly form an emulsion A;

[0044] (2) 1.8 parts of hydroxypropyl carrageenan were added to 100 parts of water at 70° C. and stirred until completely dissolved, and then 16 parts of oxalic acid and 4 parts of H2SO4 (added in the form of dilute sulfuric acid, with the water content controlled at 16 parts and the total amount of H2SO4 controlled at 4 parts) were added and stirred evenly to form solution B;

[0045] (3) The emulsion A obtained in step (1) and the solution B obtained in step (2) constitute the concrete surface retarder, and the emulsion A and the solution B are stored separately before use.

[0046] The spraying method is:

[0047] Spray emulsion A evenly on the concrete surface through atomization equipment, and control the spraying amount at 0.15kg / m 2 ;

[0048] After spraying emulsion A, let it stand for 4 minutes, then spray solution B immediately, with a spraying amount of 0.4kg / m 2 .

[0049] Example 4

[0050] The difference from Example 3 is that the spraying amount of emulsion A is 0.1 kg / m 2 .

[0051] Example 5

[0052] The difference from Example 3 is that the spraying amount of emulsion A is 0.2 kg / m 2 .

[0053] Example 6

[0054] The difference from Example 3 is that the spraying amount of solution B is 0.3 kg / m 2 .

[0055] Example 7

[0056] The difference from Example 3 is that the spraying amount of solution B is 0.5 kg / m 2 .

[0057] Comparative Example 1

[0058] The difference from Example 3 is that no sodium-based zeolite is added.

[0059] Comparative Example 2

[0060] The difference from Example 3 is that no strongly acidic cation exchange resin is added.

[0061] Comparative Example 3

[0062] The difference from Example 3 is that 15 parts of strongly acidic cation exchange resin are added.

[0063] Comparative Example 4

[0064] The difference from Example 3 is that hydroxypropyl carrageenan is not added.

[0065] Comparative Example 5

[0066] The difference from Example 3 is that 3 parts of hydroxypropyl carrageenan are added.

[0067] Comparative Example 6

[0068] The difference from Example 3 is that oxalic acid is not added.

[0069] Comparative Example 7

[0070] The difference from Example 3 is that 30 parts of oxalic acid are added.

[0071] Comparative Example 8

[0072] The difference from Example 3 is that no dilute sulfuric acid is added.

[0073] Comparative Example 9

[0074] The difference from Example 3 is that 10 parts of H2SO4 are added.

[0075] The method of using the surface retarder of the above comparative examples 1 to 9 is as follows:

[0076] Spray emulsion A evenly on the concrete surface through atomization equipment, and control the spraying amount at 0.15kg / m 2 ;

[0077] After spraying emulsion A, let it stand for 4 minutes, then spray solution B immediately, with a spraying amount of 0.4kg / m 2 .

[0078] Comparative Example 10

[0079] Compared with Example 3, emulsion A and solution B were mixed evenly to form a retarder, which was directly sprayed on the surface, and the spraying amount was controlled at 0.55 kg / m 2 .

[0080] Comparative Example 11

[0081] In the method of use of Example 3, after spraying A, spray B directly without letting it stand for 4 minutes.

[0082] Comparative Example 12

[0083] In the method of use of Example 3, the spraying amount of emulsion A is 0.05 kg / m 2 .

[0084] Comparative Example 13

[0085] In the method of use of Example 3, the spraying amount of emulsion A is 0.3 kg / m 2 .

[0086] Comparative Example 14

[0087] In the method of use of Example 3, the spraying amount of solution B is 0.1 kg / m 2 .

[0088] Comparative Example 15

[0089] In the method of use of Example 3, the spraying amount of solution B is 0.5 kg / m 2 .

[0090] The performance of the concrete surface retarder was tested according to the provisions of "Concrete Surface Retarder" JC / T 2624-2021. When testing the etching depth, the molding surface was used as the application surface of the surface retarder. The results are shown in Table 1.

[0091] Table 1 Concrete performance test after spraying surface retarder in each embodiment and comparative example

[0092]

[0093]

[0094] From the data in Table 1, we can find that:

[0095] Comparison of Examples 1 to 7 shows that the concrete surface retarder prepared by the preparation method and the use method of the present invention can exhibit good anti-sagging properties, compressive strength and etching depth.

[0096] Further comparison of Example 3, Example 4, Example 5, Comparative Example 12, and Comparative Example 13 shows that with the increase in the amount of emulsion A sprayed, the anti-sagging and etching depth of the surface retarder both show a trend of first increasing and then decreasing. The compressive strength is not much different at low spraying amounts, and the compressive strength decreases after increasing the spraying amount. This shows that emulsion A is particularly optimal in terms of dosage range after being added as a calcium ion absorber. Under low dosage conditions, it is not possible to absorb enough calcium ions, so that cement hydration continues, and the etching depth becomes shallower. Since it absorbs less calcium ions, the calcium ions chelated by B are reduced, gel formation is less, adhesion is weak, and anti-sagging properties decrease. When A is added at a high dosage, it absorbs too much calcium ions, causing the concrete surface to slow down too deeply, the adhesion between particles decreases, the anti-sagging properties decrease, and the compressive strength decreases.

[0097] Further comparison of Example 3, Example 6, Example 7, Comparative Example 14, and Comparative Example 14 shows that with the increase in the amount of emulsion B sprayed, the anti-sagging and etching depth of the surface retarder both show a trend of first increasing and then decreasing. The compressive strength is not much different at low spraying amounts, and the compressive strength decreases after increasing the spraying amount. This shows that the emulsion A is particularly optimal in the dosage range after being added as a calcium ion absorber. Under low dosage conditions, after A absorbs calcium ions, the B layer cannot continue to bind calcium ions, resulting in the reverse exchange of calcium ions between the A layer calcium ions and the concrete surface, promoting the continuous cement hydration, resulting in the shallowing of the etching depth, and because the B layer binds and absorbs less calcium ions, the calcium ions chelated by B are reduced, the gel formation is less, the bonding force is weak, and the anti-sagging property decreases. When the B dosage is high, A absorbs too much calcium ions, causing the concrete surface to slow down too deeply, the adhesion between particles decreases, the anti-sagging property decreases, and the compressive strength decreases. Therefore, A and B should be controlled within a suitable spraying thickness range.

[0098] Compared with the results of Example 3, the anti-sagging property of Comparative Example 1 is significantly reduced, the etching depth becomes shallower, and the compressive strength ratio decreases. The main function of sodium-based zeolite is to exchange ions with calcium ions and reduce the calcium ion content in the cement paste. In the absence of sodium-based zeolite, the calcium ion exchange effect is weakened, the content of calcium silicate generated increases, the etching depth changes, and the surface anti-sagging performance decreases.

[0099] Compared with the results of Example 3, the anti-sagging property of Comparative Example 2 is significantly reduced, the etching depth becomes shallower, and the compressive strength ratio decreases. The main function of the strong acid cation exchange resin is to absorb and exchange a large amount of calcium ions, reduce the calcium ion content in the cement paste, thereby increasing the silicate ion content in the solution, and the silicate ions and the sodium ions provided by the sodium-based zeolite generate high-modulus sodium silicate, thereby improving the anti-sagging property and viscosity of the surface interface. In the absence of the strong acid cation exchange resin, the calcium ion exchange effect is weakened, the content of calcium silicate generated increases, and the performance is reduced.

[0100] Compared with the results of Example 3, the etching depth in Comparative Example 3 becomes deeper and the compressive strength ratio decreases significantly. If the amount of strongly acidic cation exchange resin added is too high, excessive calcium ions will be absorbed, resulting in excessive slow setting of concrete and too deep penetration of slow setting depth, affecting the quality of the project.

[0101] Compared with the results of Example 3, the anti-sagging property of Comparative Example 4 is significantly reduced, the etching depth becomes shallower, and the compressive strength ratio decreases. The main function of hydroxypropyl carrageenan is to provide calcium ion binding effect and gel viscosity, thereby improving the surface anti-sagging property. Without the addition of hydroxypropyl carrageenan, the calcium ion binding effect is lacking, resulting in premature saturation of the calcium ion absorber, inability to continuously absorb calcium ions, weakened delay effect on cement hydration, weakened surface retarding effect, and reduced anti-sagging property.

[0102] Compared with the results of Example 3, the anti-sagging property of Comparative Example 5 is significantly reduced, and the compressive strength ratio is reduced. Adding too much hydroxypropyl carrageenan will cause the carrageenan to bind too many calcium ions, thereby causing excessive gelation, resulting in weakened adhesion between the gel and concrete, and the gel itself is too large, resulting in overall peeling, which leads to increased sagging.

[0103] Compared with the results of Example 3, the anti-sagging property in Comparative Example 6 is significantly reduced, the etching depth becomes shallower, and the compressive strength ratio decreases. Oxalic acid mainly provides the function of binding calcium ions and precipitating calcium ions, preventing calcium ions from participating in cement hydration reaction, thereby delaying cement coagulation. When calcium oxalate is not added, the binding capacity of calcium ions is weakened. Even if the calcium ion absorbent fully absorbs calcium ions, there is still a problem of premature saturation, resulting in the inability to continuously absorb calcium ions, weakening the delay effect on cement hydration, and weakening the surface retarding effect. Moreover, the calcium oxalate generated by the combination of oxalic acid and calcium ions itself has a retarding effect. Without the participation of oxalic acid, the retarding effect of the concrete surface is weakened, and the etching depth becomes shallower.

[0104] Compared with the results of Example 3, the anti-sagging property of Comparative Example 7 is significantly reduced, and the compressive strength ratio is reduced. Adding excessive oxalic acid results in the inability of oxalic acid to completely generate calcium oxalate, and part of the oxalic acid penetrates into the concrete structure, destroying a large area below the surface, which has an adverse effect on the concrete structure, significantly reduces the compressive strength ratio, and also reduces the anti-sagging property.

[0105] Compared with the results of Example 3, the anti-sagging property in Comparative Example 8 is significantly reduced, the etching depth becomes shallower, and the compressive strength ratio decreases. Dilute sulfuric acid mainly provides the function of binding calcium ions and precipitating calcium ions, avoiding calcium ions from participating in cement hydration reaction, thereby delaying cement coagulation. When dilute sulfuric acid is not added, the binding capacity of calcium ions is weakened. Even if the calcium ion absorbent fully absorbs calcium ions, there is still a problem of premature saturation, resulting in the inability to continuously absorb calcium ions, weakening the delaying effect on cement hydration, and weakening the surface retarding effect. And the calcium sulfate generated by the combination of sulfuric acid and calcium ions has a retarding effect itself. Without the participation of dilute sulfuric acid, the retarding effect of the concrete surface is weakened, and the etching depth becomes shallower. The above-mentioned effect is the same as that of oxalic acid. In addition, dilute hydrochloric acid is a strong acid, and the hydrogen ions ionized in the solution can quickly penetrate and change the alkaline environment on the surface, delaying the formation of hydration products, and the generated calcium sulfate is further attached to the surface of cement hydration products, hindering the continuous hydration of cement.

[0106] Compared with the results of Example 3, the anti-sagging property of Comparative Example 9 is significantly reduced, and the compressive strength ratio is reduced. Adding excessive dilute sulfuric acid will cause serious corrosion on the concrete surface, seriously damage the overall structure, and cause damage to the double-layer structure of the surface retarder (the inner layer absorbs calcium ions, and the outer layer binds calcium ions), resulting in a weakened continuous retarding effect, resulting in a weakened anti-sagging property, and an excessive decrease in the compressive strength ratio. In addition, excessive and rapid calcium sulfate generation is prone to generate calcium sulfate under alkaline conditions, which causes secondary coverage on the surface, making the etching depth shallower and the compressive strength ratio decreased. Therefore, too much dilute sulfuric acid should not be added to avoid its adverse effects.

[0107] Compared with the results of Example 3, the anti-sagging property of Comparative Example 10 is significantly reduced, the etching depth becomes shallower, and the compressive strength ratio decreases. This is mainly because the two-step treatment is mainly to separate the calcium ion absorber and the calcium ion precipitator, first absorbing and then precipitating, which plays a continuous retarding effect. If they are sprayed together, the retarding effect decreases.

[0108] Compared with the results of Example 3, the anti-sagging property of Comparative Example 11 is significantly reduced, the etching depth becomes shallower, and the compressive strength ratio decreases. The purpose of standing is to allow the calcium ion absorber to absorb a part of the calcium ions after spraying, and then spraying the calcium ion precipitant to ensure that the calcium ion precipitant binds the calcium ions absorbed and replaced in the calcium ion absorber. If the calcium ion precipitant is not allowed to stand for the absorbent to absorb calcium ions, the calcium ion precipitant will penetrate the absorption layer and act on the concrete, resulting in a decrease in both absorption and precipitation capabilities.

Claims

1. A method for preparing a concrete surface retarder, characterized in that: The steps include: (1) After xanthan gum is added to water and completely dissolved, sodium-based zeolite and strongly acidic cation exchange resin are added and ultrasonically dispersed to form an emulsion A; (2) adding hydroxypropyl carrageenan to solvent water and stirring until completely dissolved, then adding oxalic acid and dilute sulfuric acid and stirring evenly to form solution B; (3) The emulsion A obtained in step (1) and the solution B obtained in step (2) constitute the concrete surface retarder, and the emulsion A and the solution B are stored separately before use.

2. The preparation method according to claim 1, characterized in that: The mass fractions of each raw material component in step (1) are as follows:

3. The preparation method according to claim 1, characterized in that: The ultrasonic dispersion in step (1) is carried out at a frequency of not less than 60 Hz for 3 to 5 minutes.

4. The preparation method according to claim 1, characterized in that: The strongly acidic cation exchange resin in step (1) is selected from one of sulfonic acid polystyrene resin, chlorinated polyphenylene vinyl resin and chlorinated methyl acrylate.

5. The preparation method according to claim 1, characterized in that: The mass fractions of each raw material component in step (2) are as follows:

6. The preparation method according to claim 1, characterized in that: The temperature of adding the solvent water in step (2) is between 60°C and 80°C.

7. The preparation method according to claim 1, characterized in that: The mass ratio of emulsion A to solution B in the concrete surface retarder in step (3) is 1-2:3-5.

8. A method for using the concrete surface retarder obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The steps include: (1) Spray emulsion A evenly on the concrete surface through atomization equipment, and control the spraying amount to 0.1-0.2 kg / m 2 ; (2) After spraying emulsion A, let it stand for 3 to 5 minutes, then immediately spray solution B at a spraying rate of 0.3 to 0.5 kg / m 2 .

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