Multi-ring structure reducing agent, alkali-free liquid accelerating admixture and preparation method thereof

Abstract

The present invention relates to a polycyclic structure shrinkage reducing agent, an alkali-free liquid accelerating agent and a preparation method thereof. Among them, the polycyclic structure shrinkage reducing agent comprises the following raw materials: fulvic acid, oleic acid alkanolamine, catalyst, inhibitor; the molar ratio of the fulvic acid to the oleic acid alkanolamine is 1:(1-3); the oleic acid alkanolamine comprises at least one of linoleyl ethanolamine, triisopropanolamine oleate, arachidonic acid ethanolamine, and triisopropanolamine linoleate. The alkali-free liquid accelerating agent comprises the following raw materials in parts by weight: 5-10 parts of the polycyclic structure shrinkage reducing agent according to any one of claims 1-4, 1-4 parts of a stabilizer, 30-60 parts of an aluminum salt, 3-15 parts of an alkanolamine, and 20-30 parts of water.

Description

Technical Field

[0001] The present invention relates to the field of admixtures, and particularly to polycyclic structure shrinkage reducing agents, alkali-free liquid accelerating agents and their preparation methods. Background Art

[0002] In recent years, the infrastructure construction in China has been continuously developing, the construction processes of highways and railways have been continuously advancing, and the number and mileage of tunnels have been increasing. Shotcrete construction technology is an effective construction method for strengthening tunnel structures and preventing their collapse in tunnels. In addition to tunnel projects, shotcrete is also widely used in mine shafts, bridge reinforcement, geotechnical slopes, municipal engineering, underground engineering and other fields. Accelerating agents are key raw materials in the process of shotcrete construction. They can improve the setting and hardening speed of shotcrete, reduce its rebound loss, form sufficient strength in a short time, and ensure construction requirements.

[0003] In the preparation process of alkali-free liquid accelerating agents, fluoroaluminum complexes are often added as accelerating components, and appropriate amounts of chlorides are added as accelerating and early strength components. However, the addition of fluoroaluminum complexes is not conducive to the development of concrete strength and there are great risks in the preparation, while the addition of chlorides will corrode steel bars and reduce the durability of concrete. Therefore, the research and development of chlorine-free and alkali-free liquid agents has always been a research hotspot in the admixture industry, and their popularization and application are of great significance for improving the construction performance, mechanical properties and durability of concrete. At the same time, because after adding the accelerating agent, a large amount of free water existing between cement particles is quickly absorbed by unhydrated particles, thus accelerating the hydration of cement; the longer the curing time of shotcrete under humid conditions, the smaller the shrinkage amount. If too much water evaporates during the early hardening process of shotcrete, obvious reticulated shrinkage cracks will appear on the surface of shotcrete. Drying shrinkage is a process that gradually develops from the surface of concrete inward, which will cause internal stress and residual deformation. The shape and size of shotcrete are different, and this residual deformation is also different. If the thickness of shotcrete varies greatly, the thinner parts tend to crack due to rapid water evaporation. Therefore, keeping the surface of sprayed concrete in a moist state can slow down shrinkage and internal stress, thus reducing the risk of cracking.

[0004] Patent CN114956653A Coordination Accelerator, Liquid Alkali-Free Quick-Setting Agent and Its Preparation Method and Application. The coordination accelerator is a high molecular multi-component copolymer of monomer maleic acid triethanolamine ester, unsaturated amide and unsaturated silane. The unsaturated amide is at least one of N-hydroxymethyl acrylamide, N-hydroxyethyl acrylamide, N,N-dimethyl acrylamide, N,N-dimethyl methacrylamide, N,N-diethyl acrylamide, N,N-diethyl methacrylamide, N,N-dibutyl acrylamide, N-isopropyl acrylamide, N-phenyl acrylamide, N-phenyl methacrylamide, N-(p-hydroxyphenyl) methacrylamide; The high-early-strength liquid alkali-free quick-setting agent provided by the invention is fluorine-free and chlorine-free, has a rapid 6h compressive strength development, and at the same time has the characteristics of being fluorine-free and chlorine-free, good stability, low dosage, fast setting, and high later strength retention rate. It can be widely used in engineering construction applications such as traffic tunnels, mine roadway support, repair and reinforcement, and waterproof plugging. Although the patent creatively adds a high molecular multi-component copolymer synthesized from maleic acid triethanolamine ester, unsaturated amide and unsaturated silane, it does not solve the problem of high shrinkage rate of shotcrete, and the organic substances and synthesis methods used in this patent are also different.

[0005] Patent CN111747675B discloses an alkali-free quick-setting agent and its preparation method and application. The raw materials for preparing the alkali-free quick-setting agent include: aluminum sulfate, organic amine, fluoride salt, magnesium salt, weak acid type co-catalyst, epoxy resin, epoxy curing agent and water. The alkali-free quick-setting agent of the invention can still make the concrete set quickly with a very low dosage, has a short initial setting time and final setting time, high one-day strength, and can make the later strength have a high strength retention rate, and does not pollute the environment during the production process, and the product is safe and reliable. Although the patent has high early strength, the added epoxy resin and epoxy curing agent have poor hydrophilicity, the process modification is relatively complex, and the shrinkage reduction component is not added to the material composition, so it is difficult to change the problem of large shrinkage of shotcrete.

[0006] Patent CN114436559A discloses a method for preparing a liquid alkali-free accelerating agent by ring-opening of cyclic amide monomers. A liquid alkali-free accelerating agent is prepared by first ring-opening polymerization, then amidation reaction to synthesize a comb-shaped organic complexing agent, and then compounding multi-components, that is, ring-opening polymerization of cyclic amide monomers to prepare a main chain of a polymer, then amidation reaction with a small molecule polypeptide to obtain a comb-shaped organic complexing agent, and then compounding with aluminum sulfate, montmorillonite powder, alkanolamine, etc. to obtain a liquid alkali-free accelerating agent. The inventive method uses a self-made comb-shaped organic complexing agent, which can be widely used in the preparation of liquid alkali-free accelerating agents, greatly improving the stability of the accelerating agent, well solving problems such as precipitation and stratification of the accelerating agent, and when applied to cement-based materials, can effectively accelerate the setting rate of cement-based materials, improve the early strength, have a high late strength retention rate and no backshrinkage, showing more excellent effect and application adaptability than conventional liquid alkali-free accelerating agents, and having a broad market prospect. The organic synthesis process of first ring-opening and then amidation in this accelerating agent is relatively complex, and this patent does not use fulvic acid for organic synthesis, with different material selections from this patent, and the accelerating agent described in this patent does not have the effect of reducing concrete shrinkage. Summary of the Invention

[0007] In view of the prior art, the present invention has developed a polycyclic structure shrinkage reducing agent, an alkali-free liquid accelerating agent and a preparation method thereof. The prepared accelerating agent can reduce the late shrinkage of shotcrete, and at the same time does not affect the early coagulation promoting effect of the accelerating agent.

[0008] Based on this, the present invention provides a polycyclic structure shrinkage reducing agent, comprising the following raw materials: fulvic acid, oleic acid alkanolamine, catalyst, inhibitor; the molar ratio of the fulvic acid to the oleic acid alkanolamine is 1:(1 - 3); the oleic acid alkanolamine includes at least one of linoleyl ethanolamine, triisopropanolamine oleate, arachidonic acid ethanolamine, and triisopropanolamine linoleate.

[0009] Preferably, the oleic acid alkanolamine is linoleyl ethanolamine.

[0010] Further, the catalyst includes at least one of concentrated sulfuric acid, p-toluenesulfonic acid, stannous oxide, and dibutyltin oxide.

[0011] Further, the inhibitor includes at least one of p-methoxyphenol, hydroquinone, and phenothiazine.

[0012] Further, the preparation method of the polycyclic structure shrinkage reducing agent is: after blending the fulvic acid and the oleic acid alkanolamine, adding the catalyst and the inhibitor, and reacting at 80 - 120 °C for 4 - 5 h, the polycyclic structure shrinkage reducing agent is obtained.

[0013] The second object of the present invention is to provide a non-alkali liquid accelerating admixture, which comprises the following raw materials in parts by weight: 5-10 parts of the polycyclic structure shrinkage reducing agent described in any one of claims 1-4, 1-4 parts of a stabilizer, 30-60 parts of an aluminum salt, 3-15 parts of an alkanolamine, and 20-30 parts of water.

[0014] Further, the stabilizer comprises at least one of magnesium aluminum silicate, sepiolite, hydroxyethyl carboxymethyl cellulose ether, white carbon black, polyacrylamide, nano-silica, and magnesium silicate hydrate.

[0015] Further, the aluminum salt comprises at least one of aluminum sulfate, polyaluminum sulfate, nano-aluminum oxide, nano-aluminum hydroxide, and magnesium aluminum sulfate.

[0016] Further, the alkanolamine comprises at least one of triethanolamine, diethanolamine, triisopropanolamine, diethylene glycol, and N,N-dimethylethanolamine.

[0017] The third object of the present invention is to provide a method for preparing a non-alkali liquid accelerating admixture, which comprises the following steps: adding water, the polycyclic structure shrinkage reducing agent, and the stabilizer into a reaction kettle and stirring for 2-3 h, then adding the aluminum salt and stirring at 45-55 °C for 3-4 h; finally adding the alkanolamine and adjusting the pH value to above 2.0 to obtain the non-alkali liquid accelerating admixture.

[0018] In summary, the present invention has the following beneficial effects:

[0019] 1. In the present invention, fulvic acid with good hydrophilicity is esterified with linoleyl ethanolamine to prepare a polycyclic structure shrinkage reducing agent. The polycyclic structure shrinkage reducing agent is a network organic shrinkage reducing agent with a polycyclic structure. After the good hydrophilicity of fulvic acid is esterified with linoleyl ethanolamine, the disadvantage of poor hydrophilicity of oleic acid-based alkanolamines is effectively overcome, and at the same time, it has a good foam stabilizing effect, which helps to reduce the shrinkage of concrete; secondly, the network structure of fulvic acid and its rich cyclic groups have a relatively large molecular weight, which can effectively reduce the surface tension of water molecules, achieving a shrinkage reduction and crack resistance effect. This shrinkage reducing agent does not affect the accelerating effect of the accelerating admixture, and at the same time can reduce the shrinkage of shotcrete, effectively extending the durability of shotcrete; at the same time, the alkanolamine group carried by the shrinkage reducing agent molecule can also improve the early strength of concrete, ensuring good 6 h and 1 d strengths of shotcrete; finally, the network structure of the shrinkage reducing agent molecule can effectively solve the problem of stratification and precipitation of the accelerating admixture caused by the hydrolysis of the aluminum salt in the accelerating admixture, improving the stability of the accelerating admixture.

[0020] 2. The non-alkali liquid accelerating admixture prepared by the present invention can reduce the late shrinkage and cracking problems of shotcrete, and at the same time does not affect the early accelerating effect of the accelerating admixture. The concrete rebound rate is small, avoiding the disadvantage of slow initial setting time of concrete caused by adding a retarder, improving the durability of shotcrete, and extending the service life of the shotcrete structure. Detailed implementation manners

[0021] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0022] In the following experimental methods in the embodiments, unless otherwise specified, they are all conventional methods. The test materials and reagents used in the following embodiments, unless otherwise specified, can all be obtained from commercial channels. In the following quantitative tests in the embodiments, three repeated experiments are set, and the data are the average value or the average value ± standard deviation of the three repeated experiments.

[0023] In addition, "and / or" throughout the text includes three scenarios. Taking A and / or B as an example, it includes the technical solution of A, the technical solution of B, and the technical solution that both A and B are satisfied at the same time. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to achieve. When the combination of technical solutions conflicts with each other or cannot be achieved, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0024] Embodiment 1

[0025] A method for preparing an alkali-free liquid accelerating agent includes the following steps:

[0026] S1. After blending fulvic acid and linoleyl ethanolamine, p-toluenesulfonic acid and hydroquinone are added, and the reaction is carried out at 110 °C for 4 h to obtain a polycyclic structure shrinkage reducing agent.

[0027] S2. Water, the polycyclic structure shrinkage reducing agent, and magnesium aluminum silicate are added to a reaction kettle and stirred for 2 h, then polyaluminum sulfate is added, and the mixture is stirred at 50 °C for 4 h; finally, triisopropanolamine is added to adjust the pH value to above 2.0 to obtain an alkali-free liquid accelerating agent.

[0028] The preparation steps of the alkali-free liquid accelerating agent in Embodiments 2-6 are the same as those in Embodiment 1. The raw material dosages of the shrinkage reducing agent and the accelerating agent in Embodiments 1 to 6 are shown in Tables 1 and 2.

[0029] Table 1 Raw material dosages of the polycyclic structure shrinkage reducing agent in each embodiment (by weight parts)

[0030]

[0031] Table 2 Raw material dosages of the accelerating agent in each embodiment (by weight parts)

[0032]

[0033] The difference between Comparative Example 1 and Example 1 is that the polycyclic structure shrinkage reducing agent is not added to the raw materials of the accelerating agent.

[0034] The difference between Comparative Example 2 and Example 1 is that in the raw materials of the shrinkage reducing agent, linoleyl ethanolamine is replaced by diethylene glycol amine.

[0035] The difference between Comparative Example 3 and Example 1 is that in the raw materials of the shrinkage reducing agent, linoleyl ethanolamine is replaced by N,N-dimethylethanolamine.

[0036] The difference between Comparative Example 4 and Example 1 is that in the raw materials of the shrinkage reducing agent, fulvic acid is replaced by tannic acid.

[0037] The difference between Comparative Example 5 and Example 1 is that in the raw materials of the shrinkage reducing agent, fulvic acid is replaced by tartaric acid.

[0038] Performance test of accelerating agent

[0039] The accelerating agents prepared in Examples 1-6 and Comparative Examples 1-5 were subjected to performance tests at a cement admixture of 6% according to GB / T 35159-2017. The test results are shown in Table 3:

[0040] Table 3 Performance comparison of accelerating agents

[0041]

[0042] It can be seen from the experimental data in Table 3 that the accelerating agent prepared in the present invention has a slightly reduced setting time compared with Comparative Examples 1-5, the 6h strength is increased by 15% - 36% differently, the early strength is greatly improved, the 1d strength is slightly increased, the 28d compressive strength ratio and the 90d compressive strength retention rate are greatly increased, and the 28d shrinkage ratio is decreased by 19% - 28% differently, and the shrinkage reducing effect is obvious.

[0043] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0044] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A polycyclic structure reducing agent, characterized in that, It comprises the following raw materials: fulvic acid, oleic acid alcohol amines, a catalyst, and an inhibitor; the molar ratio of the fulvic acid to the oleic acid alcohol amines is 1:(1 - 3); the oleic acid alcohol amines include at least one of linoleyl ethanolamine, triisopropanolamine oleate, arachidonic acid ethanolamine, and triisopropanolamine linoleate; the polycyclic structure reducer is obtained by an esterification reaction of the fulvic acid and the oleic acid alcohol amines.

2. The polycyclic structure reducing agent according to claim 1, characterized in that: The catalyst includes at least one of concentrated sulfuric acid, p-toluenesulfonic acid, stannous oxide, and dibutyltin oxide.

3. The polycyclic structure reducing agent according to claim 1, characterized in that: The inhibitor includes at least one of p-methoxyphenol, hydroquinone, and phenothiazine.

4. The polycyclic structure reducing agent according to claim 1, characterized in that, The preparation method of the polycyclic structure reducer is as follows: blend the fulvic acid and the oleic acid alcohol amines, then add the catalyst and the inhibitor, and react at 80 - 120 °C for 4 - 5 h to obtain the polycyclic structure reducer.

5. An alkali-free liquid accelerating agent, characterized in that, By weight, it comprises the following raw materials: 5 - 10 parts of the polycyclic structure reducer according to any one of claims 1 - 4, 1 - 4 parts of a stabilizer, 30 - 60 parts of an aluminum salt, 3 - 15 parts of an alcohol amine, and 20 - 30 parts of water.

6. The alkali-free liquid accelerating agent according to claim 5, characterized in that: The stabilizer includes at least one of magnesium aluminum silicate, sepiolite, hydroxyethyl carboxymethyl cellulose ether, white carbon black, polyacrylamide, nano-silica, and magnesium silicate hydrate.

7. The alkali-free liquid accelerating agent according to claim 5, characterized in that: The aluminum salt includes at least one of aluminum sulfate, polyaluminum sulfate, nano-aluminum oxide, nano-aluminum hydroxide, and magnesium aluminum sulfate.

8. The alkali-free liquid accelerating agent according to claim 5, characterized in that: The alcohol amine includes at least one of triethanolamine, diethanolamine, triisopropanolamine, diethylene glycol, and N,N-dimethylethanolamine.

9. A method for preparing the alkali-free liquid accelerating agent according to any one of claims 5-8, characterized in that, It includes the following steps: Add water, the polycyclic structure reducer, and the stabilizer into a reaction kettle and stir for 2 - 3 h, then add the aluminum salt and stir at 45 - 55 °C for 3 - 4 h; finally, add the alcohol amine and adjust the pH value to above 2.0 to obtain the alkali-free liquid accelerator.

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