Liquid retarding expanding agent, water reducing agent capable of compensating shrinkage and preparation methods of liquid retarding expanding agent and water reducing agent

Abstract

The invention relates to the technical field of building materials, in particular to a liquid retarding expanding agent, a water reducing agent capable of compensating shrinkage and a preparation method.The liquid retarding expanding agent is prepared from, by mass, 10% of refined cotton, 10% of alkaline matter, 10% of acid solution, 1% of initiator, 5-10% of complexing agent, 5-10% of magnesium salt and the balance water. The invention aims to prepare a liquid expanding agent by optimizing the formula of the expanding agent, the liquid expanding agent has good solubility in a water reducing agent, and the expanding agent not only has water retention and air entraining effects, but also has good complexing, retarding and expanding effects in concrete, so that the water reducing agent with the expanding agent and a viscosity reduction type polycarboxylic acid mother liquor has good water-retaining and air-entraining effects, and the viscosity reduction type polycarboxylic acid mother liquor has good water-retaining and air-entraining effects. The viscosity of the concrete can be reduced, the concrete is slightly expanded, the shrinkage phenomenon of the high-flowability concrete is reduced and compensated, and the problems that the high-flowability concrete is prone to disengaging and cracking are solved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a liquid retarding expansion agent and a water reducing agent capable of compensating for shrinkage, and a preparation method thereof. Background Art

[0002] In recent years, with the advancement of science and technology, the increase in labor costs and the improvement of quality awareness, the degree of mechanization and construction technology difficulty of the concrete construction industry have become increasingly higher. Traditional concrete construction is limited by the performance of concrete and requires more manpower for mechanical vibration. However, due to the increase in labor costs, changes in labor concepts and the limitation of working space, concrete generally suffers from over-vibration or missed vibration during the vibration process. Therefore, in the actual construction process, the fluidity of concrete is relatively high, and the slump of concrete is generally 220-240mm to reduce manual spreading and vibration. However, as the fluidity of concrete increases, concrete is prone to stratification and large shrinkage, resulting in large strength discreteness, internal voids, cracking and other phenomena after concrete molding, especially in the construction of tunnel secondary linings with narrow working space.

[0003] At present, the main components of water reducing agents on the market are water reducing components, retarding components, and air content regulating components. By adding an appropriate amount of water reducing agent to concrete, the slump of concrete can be increased, thereby increasing the fluidity of concrete, so as to be suitable for a variety of construction technologies, such as pumping, self-leveling, self-compacting, etc.; under the condition of a certain slump of concrete, the water reducing agent can significantly reduce the water consumption of concrete, thereby improving the strength of concrete and saving a certain amount of cement; and after adding the water reducing agent, the shrinkage rate of concrete after curing can also be reduced, thereby reducing cracks caused by shrinkage.

[0004] In high-fluidity concrete, as the fluidity of concrete increases, in order to ensure the construction performance of concrete, the amount of cementitious materials, sand ratio and water consumption of concrete will also increase, resulting in greater shrinkage of concrete, making the solidified concrete prone to voiding and cracking, but the water reducers on the market cannot solve this problem well. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a liquid retarding expansive agent, a water reducing agent capable of compensating for shrinkage and a preparation method thereof. By optimizing the formula of the expansive agent, a liquid expansive agent is prepared, which has good solubility in the water reducing agent. The expansive agent not only has water retention and air entraining effects, but also has good complexing, retarding and expansion effects in concrete, so that the water reducing agent having the expansive agent and the viscosity-reducing polycarboxylic acid mother liquor can reduce the viscosity of the concrete, make the concrete slightly expand, reduce and compensate for the shrinkage phenomenon of high-fluidity concrete, and thus solve the problems of degassing and cracking that are prone to occur in high-fluidity concrete.

[0006] The present invention solves the above technical problems by the following technical means: A liquid retarding expansion agent comprises the following raw materials in percentage by weight: 10% refined cotton, 10% alkaline substance, 10% acid solution, 1% initiator, 5-10% complexing agent, 5-10% magnesium salt, and the balance is water.

[0007] Preferably, the liquid retarding expansion agent is prepared by swelling and decomposing refined cotton in an alkaline environment to form cellulose, and then complexing metal magnesium ions under the action of an initiator and a complexing agent and neutralizing with an acid solution.

[0008] According to the above technical means, a liquid retarding and expansive agent with modified cellulose magnesium as the main component is prepared, which can be miscible with other components in the water reducer and has good homogeneity in the water reducer; the modified cellulose magnesium is rich in carboxyl structure and can form hydrogen bonds with water, so it has water retention and air entraining effects, and can improve the homogeneity and water sensitivity of high-fluidity concrete; the modified cellulose magnesium has a large molecular weight and a network structure. When added to concrete, it can evenly form a certain three-dimensional network structure in the concrete, which can reduce the shrinkage and cracking of the concrete; at the same time, the modified cellulose magnesium can also cause the concrete to expand to a certain extent through the action of magnesium ions, thereby compensating for the shrinkage of the concrete.

[0009] Preferably, the preparation of the liquid retarding expansion agent comprises the following steps: S1. Dispersing refined cotton in water, adding alkaline substances, and swelling at 45-60° C. for 24 hours to obtain a pretreated cellulose pulp; S2. Add magnesium salt, initiator and complexing agent to the pretreated cellulose slurry, add acid solution dropwise during stirring, and continue stirring for 4 to 6 hours to obtain modified cellulose magnesium solution.

[0010] More preferably, in step S1, during the swelling process, stirring is performed for 5 to 15 minutes every 2 to 4 hours.

[0011] Preferably, the alkaline substance is at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide; Further preferably, the alkaline substance is sodium hydroxide and calcium hydroxide mixed in a mass ratio of 4:1, with a purity of 99% or above.

[0012] Preferably, the magnesium salt is at least one of magnesium citrate, magnesium chloride, magnesium sulfate and magnesium hydroxide; Further preferably, the magnesium salt is magnesium citrate with a purity of 99% or above.

[0013] Preferably, the initiator is polyethyleneimine; Further preferably, the purity of polyethyleneimine is 99% or above.

[0014] Preferably, the complexing agent is at least one of ethylenediaminetetraacetic acid and disodium ethylenediaminetetraacetate; Further preferably, the complexing agent is disodium ethylenediaminetetraacetate with a purity of 99% or above.

[0015] Preferably, the acid solution is a dilute hydrochloric acid solution or a fluosilicic acid solution.

[0016] Further preferably, the acid solution is a fluosilicic acid solution with an effective content of 40%.

[0017] According to the above technical means, during the swelling process, stirring is performed for 5 to 15 minutes every 2 to 4 hours, so that the refined cotton can be better mixed with the alkaline substance and the swelling efficiency can be improved; the alkaline substance is a mixture of sodium hydroxide and calcium hydroxide, and the mass ratio of sodium hydroxide and calcium hydroxide is controlled to make it have good swelling properties for the refined cotton and contain calcium ions, which have a certain expansion effect in concrete and can compensate for the shrinkage of concrete; the magnesium salt is magnesium citrate, which can introduce lemon root ions, have a certain retarding effect on concrete, can slow down the slump loss of concrete over time and the concentrated release of hydration heat, can better improve the working performance and durability of concrete, and also introduce magnesium ions, which have a certain expansion effect in concrete. It has a certain expansion effect that can compensate for the shrinkage of concrete, and combined with calcium ions, it can further enhance the expansion effect; the complexing agent selected is disodium ethylenediaminetetraacetic acid, which has better water solubility and can accelerate the complexing reaction and improve the preparation efficiency; the acid solution selected is fluorosilicic acid solution, which can introduce fluorosilicic acid ions, which not only has a certain retarding effect on concrete, but also can promote the complexing of magnesium ions; and through the action of the initiator polyethyleneimine, the surface properties of cellulose formed by refined cotton can be improved, the binding ability with magnesium ions can be promoted, and the formed cellulose can be prevented from being excessively dissolved, and can be condensed to a certain extent, so that the magnesium ions can be more evenly combined with the cellulose, so that it can better combine and expand in concrete.

[0018] By regulating the purity of various substances, it is possible to reduce the interference of impurities and the amount of substances on the reaction and improve the stability of product quality.

[0019] The present application also discloses a water reducing agent capable of compensating for shrinkage, comprising the following raw materials in percentage by mass: The viscosity-reducing polycarboxylic acid water-reducing agent mother liquor is 12-20%, the slump-retaining polycarboxylic acid water-reducing agent mother liquor is 6-16%, the liquid retarding expansive agent is 10-20%, and the water is made up to 100%.

[0020] According to the above technical means, by using the viscosity-reducing polycarboxylate water-reducing agent mother liquor, since it is a polycarboxylate polymer compound containing methyl acrylate groups, the methyl acrylate groups can reduce the consistency of the cement paste, so that the concrete has moderate viscosity and good fluidity at a lower water-binder ratio, and is not easy to grab the bottom and bleed water, thereby achieving the reduction of the shrinkage of high-fluidity concrete by appropriately reducing the water-binder ratio; by using the polycarboxylate water-reducing agent slump-retaining mother liquor, the fluidity and slump of the concrete can be improved, the water-cement ratio can be reduced and the concrete performance can be enhanced, the slump-retaining time of the concrete can be extended, the early and late strength of the concrete can be greatly improved, the construction progress can be accelerated, and the engineering efficiency can be improved. At the same time, the shrinkage and creep deformation of the concrete can be reduced, and the durability and stability of the concrete can be improved; By using liquid retarding expansive agent, shrinkage can be compensated and a network can be formed, so that when the water reducer is used in concrete, the concrete will expand slightly, reducing and compensating for the shrinkage of high-fluidity concrete, and preventing the concrete from becoming hollow and cracked.

[0021] Preferably, the viscosity-reducing polycarboxylic acid water-reducing agent mother liquor is a polycarboxylic acid polymer compound containing methyl acrylate groups with a molecular weight of 20,000 to 40,000, and the effective content is ≥40%.

[0022] Preferably, the polycarboxylic acid water-reducing agent collapse-retaining mother liquor is a polycarboxylic acid polymer compound containing hydroxyethyl ester groups with a molecular weight of 40,000 to 60,000, and the effective content is ≥40%.

[0023] The present application also discloses a method for preparing a water reducing agent capable of compensating for shrinkage, comprising the following steps: S3. The viscosity-reducing polycarboxylate water-reducing agent mother liquor and the polycarboxylate water-reducing agent mother liquor were added to the reactor and stirred for 5 to 10 minutes to obtain a mixed solution; S4. Add liquid retarding expansion agent and water to the mixed solution and stir for 10 to 20 minutes to obtain a water reducing agent.

[0024] According to the above technical means, the water reducing agent can be obtained by mixing and stirring the raw materials. The operation is simple, green and environmentally friendly, and the product has good homogeneity and reliable performance.

[0025] The present application adopting the above scheme has the following beneficial effects: 1. The water reducing agent prepared in this application has a simple production process, is green and environmentally friendly, has good product homogeneity and reliable performance, can reduce the viscosity of concrete, use a lower water-binder ratio, make the concrete slightly expand, reduce and compensate for the shrinkage phenomenon of high-fluidity concrete, and prevent the concrete from becoming hollow and cracked; 2. The water-reducing agent in the present application adopts a viscosity-reducing polycarboxylate water-reducing agent mother liquor. Since it is a polycarboxylate polymer compound containing methyl acrylate groups, the methyl acrylate groups can reduce the consistency of the cement paste, so that the concrete has moderate viscosity and good fluidity at a lower water-binder ratio, and is not easy to grasp the bottom and bleed water, thereby achieving the reduction of the shrinkage of high-fluidity concrete by appropriately reducing the water-binder ratio; 3. The liquid retarding expansive agent in the water-reducing agent of the present application has modified cellulose magnesium as its main component, and its carboxyl-rich structure can form hydrogen bonds with water, has water-retaining and air-entraining effects in concrete, and can improve the homogeneity and water sensitivity of high-fluidity concrete; at the same time, its ultra-large molecular structure can complex the concrete like a network, reducing the shrinkage and cracking of the concrete; and the liquid retarding expansive agent contains a certain amount of lemon root and fluorosilicate ions, which have a good retarding effect, can slow down the slump loss of concrete over time and the concentrated release of hydration heat, and can better improve the working performance and durability of concrete; a certain amount of magnesium ions and calcium ions can cause the cement mortar to expand slightly, further compensating for the shrinkage. DETAILED DESCRIPTION

[0026] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention: The following raw materials are used in this embodiment: Sodium hydroxide, industrial grade, content ≥99%; Calcium hydroxide, industrial grade, content ≥99%; Fluorosilicic acid, industrial grade, content 40%; Polyethyleneimine, industrial grade, content ≥99%; Disodium EDTA, industrial grade, content ≥99%; Magnesium citrate, industrial grade, content ≥99%; The viscosity-reducing polycarboxylic acid water-reducing agent mother liquor is a polycarboxylic acid polymer compound containing methyl acrylate groups with a molecular weight of 20,000 to 40,000, and the effective content is ≥40%; The polycarboxylic acid water-reducing agent collapse-retaining mother liquor is a polycarboxylic acid polymer compound containing hydroxyethyl ester groups with a molecular weight of 40,000 to 60,000, and the effective content is ≥40%.

[0027] The present invention adopts the following preparation steps: A method for preparing a liquid retarding expansion agent comprises the following steps: S1. 10% refined cotton was dispersed in water, 8% sodium hydroxide and 2% calcium hydroxide were added, and the mixture was swelled at 50°C for 24 hours. During the swelling process, the mixture was stirred for 10 minutes every 3 hours to obtain a pretreated cellulose pulp; S2. Add 8% magnesium citrate, 1% polyethyleneimine and 8% disodium ethylenediaminetetraacetate to the pretreated cellulose pulp, add 10% fluorosilicic acid solution dropwise during stirring, and continue stirring for 5 hours to obtain a modified cellulose magnesium solution.

[0028] A method for preparing a water reducing agent capable of compensating for shrinkage comprises the following steps: S3 15% viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and 8% polycarboxylate water-reducing agent collapse-proof mother liquor were added to the reactor and stirred for 5 min to obtain a mixed solution; S4. Add 16% liquid retarder expansion agent and water to the mixed solution and stir for 15 minutes to obtain a water reducing agent.

[0029] Liquid retarding expansion agent formula screening test 1 By comparing different components and reaction conditions of liquid retarding expansive agent, four-factor three-level orthogonal test was carried out to obtain 9 test groups. The production process of the 9 groups of embodiments is shown in Table 1, and the rest are filled with water to 100%. The homogeneity was observed by centrifugation in a 10mL graduated test tube for 3 minutes, and the liquid retarding expansive agent was added at 0.1% of the cement dosage to determine the difference in initial setting time of cement paste and the free expansion rate of 24h mortar.

[0030] Table 1 Orthogonal test and results of liquid retarding expansion agent in Examples 1 to 9

[0031] Through orthogonal test analysis, it was found that: Regarding the influence on homogeneity, magnesium citrate (range 1.8667) > reaction temperature (range 0.767) > reaction time (range 0.4333) > disodium ethylenediaminetetraacetic acid (range 0.333), among which magnesium citrate has a more significant effect. The greater its dosage, the worse the homogeneity. For the effect of initial setting time difference, magnesium citrate (range 19.666) > disodium ethylenediaminetetraacetate (range 4.667) > reaction temperature (range 1.000) > reaction time (range 0.666), among which magnesium citrate has a particularly significant effect. The greater its dosage, the greater the initial setting time difference. For the influence on the expansion rate of mortar, magnesium citrate (range 0.147) > disodium ethylenediaminetetraacetic acid (range 0.030) > reaction temperature (range 0.020) > reaction time (range 0.020), among which the influence of magnesium citrate is particularly significant. The greater the amount used, the greater the expansion rate.

[0032] Therefore, in order to ensure the homogeneity, retarding performance, expansion performance of the liquid retarding expansive agent and consider the production efficiency and production energy consumption, in the production process of the liquid retarding expansive agent: disodium ethylenediaminetetraacetic acid is 7-9%, magnesium citrate is 7-9%, the reaction temperature is 50°C, and the reaction time is 5h.

[0033] Liquid retarder expansion agent formula screening test 2 According to the orthogonal test results of Examples 1 to 9, the amounts of disodium edetate and magnesium citrate were screened below, and the conditions were: 10% refined cotton, 8% sodium hydroxide, 2% calcium hydroxide, 10% fluorosilicic acid, 1% polyethyleneimine, 7-9% disodium edetate, 7-9% magnesium citrate, reaction temperature of 50°C, and reaction time of 5h.

[0034] Table 2 Test results of liquid expansion retarder in Examples 10 to 18

[0035] Through experimental analysis, it was found that: As for the influence on homogeneity, as the amount of magnesium citrate increases, the homogeneity becomes worse; as the amount of disodium edetate increases, the homogeneity becomes better.

[0036] As for the effect of initial setting time difference, as the amount of magnesium citrate increases, the setting time difference increases and the retarding effect becomes better; as the amount of disodium ethylenediaminetetraacetic acid increases, the setting time difference decreases and the retarding effect becomes worse.

[0037] As for the influence on the expansion rate of mortar, as the amount of magnesium citrate increases, the expansion rate increases; disodium ethylenediaminetetraacetic acid has little effect on the expansion rate.

[0038] The liquid retarding expansive agent prepared in Example 14 has a good cost performance. Therefore, in order to ensure the homogeneity, retarding performance, and expansive performance of the liquid retarding expansive agent and to consider production efficiency and production energy consumption, in the production process of the liquid retarding expansive agent, disodium ethylenediaminetetraacetic acid is 8% and magnesium citrate is 8%.

[0039] According to the results of Examples 1 to 18, the liquid retarding expansion agent prepared in Example 14 has a good cost performance ratio, and the following components in mass percentage are used: Refined cotton 10%, sodium hydroxide 8%, calcium hydroxide 2%, fluorosilicic acid 10%, polyethyleneimine 1%, disodium edetate 8% and magnesium citrate 8%, and the balance is water.

[0040] The specific preparation method is as follows: S1. 10% refined cotton was dispersed in water, 8% sodium hydroxide and 2% calcium hydroxide were added, and the mixture was swelled at 50°C for 24 hours. During the swelling process, the mixture was stirred for 10 minutes every 3 hours to obtain a pretreated cellulose pulp; S2. Add 8% magnesium citrate, 1% polyethyleneimine and 8% disodium ethylenediaminetetraacetate to the pretreated cellulose pulp, add 10% fluorosilicic acid solution dropwise during stirring, and continue stirring for 5 hours to obtain a modified cellulose magnesium solution.

[0041] Water reducing agent formulation screening test The liquid retarding expansive agent prepared in Example 14 was used to prepare a micro-expansive concrete water reducing agent for compensating shrinkage, and the content of each single component was further investigated. The formula and preparation method are as follows: Example 19 Preparation of water reducing agent A shrinkage compensating water reducing agent comprising the following components in percentage by mass: The viscosity-reducing polycarboxylic acid water-reducing agent mother liquor is 14%, the polycarboxylic acid water-reducing agent slump-retaining mother liquor is 8%, the liquid retarding expansion agent is 10%, and the water is made up to 100%.

[0042] S30. Weigh each component by mass percentage; S3. Sequentially add viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and polycarboxylate water-reducing agent collapse-preserving mother liquor to the reactor, start stirring, and stir for 5 to 10 minutes; S4. Add water and liquid retarding expansion agent into the reactor and continue stirring for 10 to 20 minutes.

[0043] Example 20 Preparation of water reducing agent II A shrinkage compensating water reducing agent comprising the following components in percentage by mass: The viscosity-reducing polycarboxylate water-reducing agent mother liquor is 14%, the slump-retaining polycarboxylate water-reducing agent mother liquor is 8%, the liquid retarding expansive agent is 20%, and the water is made up to 100%.

[0044] S30. Weigh each component by mass percentage; S3. Sequentially add viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and polycarboxylate water-reducing agent collapse-preserving mother liquor to the reactor, start stirring, and stir for 5 to 10 minutes; S4. Add water and liquid retarding expansion agent into the reactor and continue stirring for 10 to 20 minutes.

[0045] Example 21 Preparation of water reducing agent III A shrinkage compensating water reducing agent comprising the following components in percentage by mass: The viscosity-reducing polycarboxylate water-reducing agent mother liquor is 15%, the slump-retaining polycarboxylate water-reducing agent mother liquor is 8%, the liquid retarding expansive agent is 16%, and the water is made up to 100%.

[0046] S30. Weigh each component by mass percentage; S3. Sequentially add viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and polycarboxylate water-reducing agent collapse-preserving mother liquor to the reactor, start stirring, and stir for 5 to 10 minutes; S4. Add water and liquid retarding expansion agent into the reactor and continue stirring for 10 to 20 minutes.

[0047] Example 22 Preparation of water reducing agent A shrinkage compensating water reducing agent comprising the following components in percentage by mass: The viscosity-reducing polycarboxylate water-reducing agent mother liquor is 16%, the polycarboxylate water-reducing agent slump-retaining mother liquor is 8%, the liquid retarding expansive agent is 20%, and the water is made up to 100%.

[0048] S30. Weigh each component by mass percentage; S3. Sequentially add viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and polycarboxylate water-reducing agent collapse-preserving mother liquor to the reactor, start stirring, and stir for 5 to 10 minutes; S4. Add water and liquid retarding expansion agent into the reactor and continue stirring for 10 to 20 minutes.

[0049] Example 22 Preparation of water reducing agent A shrinkage compensating water reducing agent comprising the following components in percentage by mass: The viscosity-reducing polycarboxylate water-reducing agent mother liquor is 16%, the slump-retaining polycarboxylate water-reducing agent mother liquor is 6%, the liquid retarding expansive agent is 20%, and the water is made up to 100%.

[0050] S30. Weigh each component by mass percentage; S3. Sequentially add viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and polycarboxylate water-reducing agent collapse-preserving mother liquor to the reactor, start stirring, and stir for 5 to 10 minutes; S4. Add water and liquid retarding expansion agent into the reactor and continue stirring for 10 to 20 minutes.

[0051] Example 23 Preparation of water reducing agent VI A shrinkage compensating water reducing agent comprising the following components in percentage by mass: The viscosity-reducing polycarboxylate water-reducing agent mother liquor is 18%, the polycarboxylate water-reducing agent slump-retaining mother liquor is 16%, the liquid retarding expansion agent is 20%, and the water is made up to 100%.

[0052] S30. Weigh each component by mass percentage; S3. Sequentially add viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and polycarboxylate water-reducing agent collapse-preserving mother liquor to the reactor, start stirring, and stir for 5 to 10 minutes; S4. Add water and liquid retarding expansion agent into the reactor and continue stirring for 10 to 20 minutes.

[0053] Example 24 Preparation of water reducing agent A shrinkage compensating water reducing agent comprising the following components in percentage by mass: The viscosity-reducing polycarboxylic acid water-reducing agent mother liquor is 20%, the slump-retaining polycarboxylic acid water-reducing agent mother liquor is 16%, the liquid retarding expansion agent is 20%, and the water is made up to 100%.

[0054] S30. Weigh each component by mass percentage; S3. Sequentially add viscosity-reducing polycarboxylate water-reducing agent water-reducing mother liquor and polycarboxylate water-reducing agent collapse-preserving mother liquor to the reactor, start stirring, and stir for 5 to 10 minutes; S4. Add water and liquid retarding expansion agent into the reactor and continue stirring for 10 to 20 minutes.

[0055] The shrinkage compensating water reducing agent prepared in Examples 19 to 24 was applied to the high-fluidity tunnel secondary lining concrete, with the dosage being 1% of the cementitious material, and the blank sample used a common water reducing agent. The mix ratio used in the test is shown in Table 3, and the test results are shown in Table 4.

[0056] Table 3 C30 secondary lining concrete mix ratio

[0057] Table 4 Test results of water reducing agent that can compensate for shrinkage

[0058] It can be concluded from the data in Table 4 that the shrinkage compensating water reducing agent prepared in Examples 19 to 24 does not substantially affect the strength of concrete. In the high-flow secondary lining concrete (slump not less than 230 mm), it can reduce the viscosity of concrete, improve the fluidity of concrete, improve the concrete wrapping, extend the initial and final setting time of concrete and the working performance retention time, reduce the collapse time, and improve the 28d and 90d shrinkage rates of concrete, which is beneficial to the construction of secondary lining concrete in tunnels with narrow working space, reduce and compensate for the shrinkage phenomenon of high-flow concrete, and prevent the concrete from becoming hollow and cracked. This shows that the water reducing agent using a liquid retarding expansive agent in this application can improve the homogeneity and water sensitivity of high-flow concrete, reduce the shrinkage and cracking of concrete, and slow down the slump loss of concrete over time and the concentrated release of hydration heat, and can better improve the working performance and durability of concrete, and perform micro-expansion, thereby reducing and compensating for the shrinkage phenomenon of high-flow concrete, and preventing the concrete from becoming hollow and cracked.

[0059] The above is a detailed introduction to a liquid retarding expansive agent for concrete water reducing agent and a water reducing agent capable of compensating for shrinkage and a preparation method provided by the present invention. The description of the specific embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0060] It should be noted that if no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be purchased commercially.

[0061] The above examples are intended to provide a better understanding of the present invention, and are not intended to be limiting of the best implementation mode described herein, nor are they intended to limit the content and protection scope of the present invention. Any product identical or similar to the present invention that is derived by anyone under the inspiration of the present invention or by combining the present invention with features of other prior arts shall fall within the protection scope of the present invention.

Claims

1. A liquid retarding expansion agent, characterized in that: Including the following raw materials in mass percentage: 10% refined cotton, 10% alkaline substance, 10% acid solution, 1% initiator, 5-10% complexing agent, 5-10% magnesium salt, and the balance is water.

2. The liquid retarding expansion agent according to claim 1, characterized in that: The liquid retarding expansion agent is prepared by swelling and decomposing refined cotton in an alkaline environment to form cellulose, and then complexing metal magnesium ions under the action of an initiator and a complexing agent and neutralizing with an acid solution.

3. The liquid retarding expansion agent according to claim 2, characterized in that: The preparation of the liquid retarding expansion agent specifically comprises the following steps: S1. Dispersing refined cotton in water, adding alkaline substances, and swelling at 45-60° C. for 24 hours to obtain a pretreated cellulose pulp; S2. Add magnesium salt, initiator and complexing agent to the pretreated cellulose slurry, add acid solution dropwise during stirring, and continue stirring for 4 to 6 hours to obtain a liquid retarding expansion agent.

4. The liquid retarding expansion agent according to claim 3, characterized in that: In the step S1, during the swelling process, stirring is performed for 5 to 15 minutes every 2 to 4 hours.

5. The liquid retarding expansion agent according to claim 3, characterized in that: The alkaline substance is at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide; The magnesium salt is at least one of magnesium citrate, magnesium chloride, magnesium sulfate and magnesium hydroxide; The initiator is polyethyleneimine; The complexing agent is at least one of ethylenediaminetetraacetic acid and disodium ethylenediaminetetraacetate; The acid solution is at least one of a dilute hydrochloric acid solution and a fluosilicic acid solution.

6. The liquid retarding expansion agent according to claim 5, characterized in that: The alkaline substances are sodium hydroxide and calcium hydroxide, and the mass ratio of sodium hydroxide to calcium hydroxide is 4:

1.

7. A shrinkage compensating water reducing agent as claimed in any one of claims 1 to 6, characterized in that: Including the following raw materials in mass percentage: The viscosity-reducing polycarboxylic acid water-reducing agent mother liquor is 12-20%, the slump-retaining polycarboxylic acid water-reducing agent mother liquor is 6-16%, the liquid retarding expansive agent is 10-20%, and the water is made up to 100%.

8. The water reducing agent according to claim 7, characterized in that: The viscosity-reducing polycarboxylic acid water-reducing agent mother liquor is a polycarboxylic acid polymer compound containing methyl acrylate groups with a molecular weight of 20,000 to 40,000, and the effective content is ≥40%.

9. The water reducing agent according to claim 7, characterized in that: The polycarboxylic acid water-reducing agent collapse-preserving mother liquor is a polycarboxylic acid macromolecular compound containing hydroxyethyl ester groups with a molecular weight of 40,000 to 60,000, and the effective content is ≥40%.

10. A method for preparing a water reducing agent capable of compensating for shrinkage according to claim 7, characterized in that: The following steps are involved: S3. The viscosity-reducing polycarboxylate water-reducing agent mother liquor and the polycarboxylate water-reducing agent mother liquor were added to the reactor and stirred for 5 to 10 minutes to obtain a mixed solution; S4. Add liquid retarding expansion agent and water to the mixed solution and stir for 10 to 20 minutes to obtain a water reducing agent.

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