Mud-resistant slump-retaining polycarboxylic acid water reducer and preparation method thereof

Abstract

The invention relates to a mud-resistant slump-retaining polycarboxylic acid water reducer and a preparation method thereof. The polycarboxylic acid water reducer is prepared from the following raw materials: 80-100 parts of polyether macromonomer; 1-2 parts of a rigid unsaturated monomer; 1-2 parts of a crosslinking monomer; 2-3 parts of an unsaturated sulfonic acid monomer; 10 to 15 parts of unsaturated acid; 0.5-2 parts of an oxidizing agent; 0.5-2 parts of a reducing agent; and 1-2 parts of a chain transfer agent. According to the invention, ethylene glycol monovinyl ether polyoxyethylene ether is adopted as a polyether monomer, a cross-linking monomer itaconic acid polyethylene glycol ester is introduced to form a cross-linked network-shaped molecular structure, and rigid structures such as (4-vinyl phenyl) trimethoxysilane are introduced, so that friction layer adsorption of clay is avoided, adsorption sites on the surface of the clay are reduced, and the adhesion of the clay is improved; the competitive adsorption effect of clay on the polycarboxylate superplasticizer is weakened, and the mud resistance and the slump loss resistance are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, in particular to an anti-mud collapse-preserving polycarboxylate water-reducing agent and a preparation method thereof. Background Art

[0002] In the prior art, polycarboxylate water reducers are widely used in concrete engineering due to their advantages of low dosage, high water reduction rate, adjustable functions, flexible molecular design, and green environmental protection. However, with the increasing demand for natural sand and gravel in concrete production, commercial concrete companies often use recycled materials or low-quality natural sand and gravel to reduce costs. These materials generally have problems such as poor sand and gravel quality, high mud or powder content, resulting in poor workability, severe bleeding, or insufficient fluidity of concrete.

[0003] Conventional polycarboxylate water reducers have a weak adsorption capacity for mud and powder in sand and gravel, and need to be added in large quantities to achieve the desired effect, thereby increasing production costs. Although there are technologies on the market for preparing anti-mud and collapse-resistant polycarboxylate water reducers by designing molecular structures (such as products synthesized from multi-arm polymer precursors and other raw materials as described in Chinese patent application 202010854758.7), these methods are complex in process, require high dosage, and do not significantly improve the overall performance of concrete, and have limited practical application effects.

[0004] Therefore, there is an urgent need to develop a polycarboxylic acid water-reducing agent with good adaptability and excellent anti-mud collapse performance to better solve the concrete construction problems caused by low-quality sand and gravel. Summary of the invention

[0005] Based on this, it is necessary to provide an anti-mud and collapse-preserving polycarboxylic acid water-reducing agent and a preparation method thereof, in order to solve the concrete construction problems caused by low-quality sand and gravel.

[0006] To achieve the above object, the present invention provides a technical solution:

[0007] A polycarboxylate water-reducing agent for resisting mud and preventing collapse, wherein the raw materials for preparing the polycarboxylate water-reducing agent include, by weight:

[0008]

[0009]

[0010] In some embodiments, the cross-linking monomer comprises polyethylene glycol itaconate.

[0011] In some embodiments, the raw materials for preparing polyethylene glycol itaconate include, by weight:

[0012]

[0013] Specifically, itaconic acid, with a structural formula of HOOC-CH2-C(COOH)-CH2-COOH, is used as a reactant to provide a carboxylic acid group to undergo an esterification reaction with the hydroxyl group of polyethylene glycol PEG-200.

[0014] In some embodiments, the polymerization inhibitor includes hydroquinone.

[0015] In some embodiments, the catalyst includes p-p-toluenesulfonic acid.

[0016] In some embodiments, the unsaturated sulfonic acid monomer includes at least one of 2-acrylamide 2-methylpropane sulfonic acid and sodium methyl propene sulfonate.

[0017] In some embodiments, the rigid unsaturated monomer includes (4-vinylphenyl)trimethoxysilane.

[0018] In some embodiments, the polyether macromonomer includes ethylene glycol monovinyl ether polyoxyethylene ether, and the molecular weight of the ethylene glycol monovinyl ether polyoxyethylene ether is 1000-3000.

[0019] In some embodiments, the unsaturated acid includes at least one of acrylic acid, methacrylic acid and itaconic acid.

[0020] The present invention also provides a method for preparing an anti-mud collapse-preserving polycarboxylate water-reducing agent, comprising the steps of:

[0021] Dissolving the polyether macromonomer in water to obtain a solution to obtain a base material;

[0022] Add material A and material B dropwise to the base material, react at a constant temperature after the addition is complete, and adjust the pH to 5 to 7 after the reaction is complete to obtain an anti-mud and collapse-preserving water-reducing agent;

[0023] Wherein, the material A is a mixed solution obtained by dissolving unsaturated acid, cross-linking monomer, unsaturated sulfonic acid monomer, rigid unsaturated monomer and chain transfer agent in water;

[0024] The material B is a solution obtained by dissolving a reducing agent in water.

[0025] In some embodiments, the preparation steps of polyethylene glycol itaconate are as follows:

[0026] Itaconic acid, hydroquinone and p-toluenesulfonic acid are added to polyethylene glycol for reaction, and polyethylene glycol itaconic acid ester is obtained after the reaction is completed.

[0027] In some embodiments, the reaction temperature is 80-100°C.

[0028] In some embodiments, the reaction time is 2 h to 4 h.

[0029] In some embodiments, the oxidant includes at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate.

[0030] In some embodiments, the raw material for preparing the polycarboxylate water-reducing agent includes ferrous sulfate, and the mass fraction of ferrous sulfate is 0.01 parts.

[0031] In some embodiments, the unsaturated acid is acrylic acid.

[0032] In some embodiments, the chain transfer agent is at least one of mercaptoethanol, thioglycolic acid and 2-mercaptopropionic acid.

[0033] In some embodiments, the reducing agent includes at least one of sodium formaldehyde sulfoxylate and L-ascorbic acid.

[0034] Beneficial effects of the present invention:

[0035] The present invention adopts ethylene glycol monovinyl ether polyoxyethylene ether as a polyether monomer, introduces a cross-linking monomer polyethylene glycol itaconate to form a cross-linked network molecular structure, and introduces a rigid unsaturated monomer to avoid the rubbing layer adsorption of clay, reduce the adsorption sites on the clay surface, weaken the competitive adsorption effect of clay on the polycarboxylate water reducer, and greatly improve the anti-mud performance and collapse protection performance of the polycarboxylate water reducer.

[0036] The present invention introduces an unsaturated sulfonic acid monomer, which contains an unsaturated sulfonic acid group and a methoxysilane side chain, thereby reducing the adsorption of soil on the water reducer, allowing the carboxylate ions and the polyether side chains in the molecular structure to play the role of adsorbing cement and dispersing cement respectively, and better wrapping the cement particles in the water-cement system, thereby improving the anti-mud adaptability and low sensitivity, and having good anti-mud performance and collapse protection effect;

[0037] The invention introduces a side chain with a micro-crosslinked structure into the structure of the polycarboxylic acid water reducer by adding polyethylene glycol itaconate crosslinking monomer, thereby improving the spatial repulsion of the water reducer, having good mud resistance, and having an excellent sustained-release effect, and showing high adaptability to concrete with a high mud content. DETAILED DESCRIPTION

[0038] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0039] In the examples, the test methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0040] 1. Preparation of cross-linked monomer polyethylene glycol itaconate

[0041] Add polyethylene glycol PEG-200 to a four-necked flask, start stirring, add itaconic acid, then add hydroquinone and p-toluenesulfonic acid in sequence, raise the temperature to 80-100°C, introduce nitrogen, and react at a constant temperature for 2-4 hours. When the esterification reaction is completed, cool down and take out the material to obtain a brown liquid, which is the polyethylene glycol itaconic acid ester solution;

[0042] The preparation process ratio and reaction conditions of polyethylene glycol itaconate are shown in Table 1.

[0043] Table 1 Process ratio and reaction conditions

[0044]

[0045] 2. Preparation of anti-mud collapse type polycarboxylate water reducer

[0046] Example 1

[0047] Dissolve 100 parts of ethylene glycol monovinyl ether polyoxyethylene ether (molecular weight 3000) macromonomer in 100 parts of water to obtain a solution as a base material, control the temperature in the reactor at 20°C, then add 1 part of hydrogen peroxide and 7 parts of 1% ferrous sulfate to the reactor and stir evenly, then uniformly add material A and material B to the reactor, and complete the addition within 1 hour. After the addition is completed, keep the temperature constant for 0.5 hours; add 32% liquid alkali to neutralize and adjust the pH to 5-7, and add water to adjust the solid content to 50% of the anti-mud collapse type polycarboxylic acid water reducer;

[0048] Material A is a mixture of 15 parts of acrylic acid, 2 parts of crosslinking monomer a, 3 parts of 2-acrylamide 2-methylpropane sulfonic acid, 1 part of (4-vinylphenyl)trimethoxysilane, and 1 part of mercaptoethanol dissolved in 20 parts of water, and material B is a solution of 0.5 parts of sodium formaldehyde sulfoxylate dissolved in 30 parts of water.

[0049] Example 2

[0050] Dissolve 80 parts of ethylene glycol monovinyl ether polyoxyethylene ether (molecular weight 2000) macromonomer in 80 parts of water to obtain a solution as a base material, control the temperature in the reactor at 20°C, then add 1.5 parts of ammonium persulfate and 6 parts of 1% ferrous sulfate to the reactor and stir evenly, then uniformly add material A and material B to the reactor, and complete the dropwise addition within 1 hour. After the dropwise addition is completed, keep the reaction at a constant temperature for 0.5 hours; add 32% liquid alkali to neutralize and adjust the pH to 5-7, and add water to adjust the solid content to 50% of the anti-mud collapse type polycarboxylic acid water reducer;

[0051] Material A is a mixture of 13 parts of methacrylic acid, 1 part of crosslinking monomer c, 2 parts of sodium methacrylate sulfonate, 1.5 parts of (4-vinylphenyl)trimethoxysilane, and 1 part of thioglycolic acid dissolved in 20 parts of water, and material B is a solution of 0.5 parts of L-ascorbic acid dissolved in 30 parts of water.

[0052] Example 3

[0053] Dissolve 80 parts of ethylene glycol monovinyl ether polyoxyethylene ether (molecular weight 1000) macromonomer in 80 parts of water to obtain a solution as a base material, control the temperature in the reactor at 20°C, then add 2 parts of sodium persulfate and 8 parts of 1% ferrous sulfate to the reactor and stir evenly, then uniformly add material A and material B to the reactor, and complete the dropwise addition within 1 hour. After the dropwise addition is completed, keep the reaction temperature constant for 0.5 hours; add 32% liquid alkali to neutralize and adjust the pH to 5-7, and add water to adjust the solid content to 50% of the anti-mud collapse type polycarboxylic acid water reducer;

[0054] Material A is a mixture of 10 parts of itaconic acid, 1 part of crosslinking monomer b, 2 parts of 2-acrylamide 2-methylpropane sulfonic acid, 2 parts of (4-vinylphenyl)trimethoxysilane, and 2 parts of mercaptoethanol dissolved in 20 parts of water, and material B is a solution of 2 parts of L-ascorbic acid dissolved in 30 parts of water.

[0055] Example 4

[0056] Dissolve 90 parts of ethylene glycol monovinyl ether polyoxyethylene ether (molecular weight 3000) macromonomer in 90 parts of water to obtain a solution as a base material, control the temperature in the reactor at 20°C, then add 1 part of potassium persulfate and 5 parts of 1% ferrous sulfate to the reactor and stir evenly, then uniformly add material A and material B to the reactor, and complete the addition within 1 hour. After the addition is completed, keep the temperature constant for 0.5 hours; add 32% liquid alkali to neutralize and adjust the pH to 5-7, and add water to adjust the solid content to 50% of the anti-mud collapse type polycarboxylic acid water reducer;

[0057] Material A is a mixture of 10 parts of acrylic acid, 1 part of crosslinking monomer d, 3 parts of sodium methyl propylene sulfonate, 2 parts of (4-vinylphenyl)trimethoxysilane, and 2 parts of 2-mercaptopropionic acid dissolved in 20 parts of water, and material B is a solution of 2 parts of L-ascorbic acid dissolved in 30 parts of water.

[0058] Example 5

[0059] Dissolve 100 parts of ethylene glycol monovinyl ether polyoxyethylene ether (molecular weight 2000) macromonomer in 100 parts of water to obtain a solution as a base material, control the temperature in the reactor at 20°C, then add 1 part of potassium persulfate and 10 parts of 1% ferrous sulfate to the reactor and stir evenly, then uniformly add material A and material B to the reactor, and complete the dropwise addition within 1 hour. After the dropwise addition is completed, keep the temperature constant for 0.5 hours; add 32% liquid alkali to neutralize and adjust the pH to 5-7, and add water to adjust the solid content to 50% of the anti-mud collapse type polycarboxylic acid water reducer;

[0060] Material A is a mixture of 15 parts of methacrylic acid, 2 parts of crosslinking monomer a, 2 parts of 2-acrylamide 2-methylpropane sulfonic acid, 1 part of (4-vinylphenyl)trimethoxysilane, and 1.5 parts of 2-mercaptopropionic acid dissolved in 20 parts of water, and material B is a solution of 0.5 parts of sodium formaldehyde sulfoxylate dissolved in 30 parts of water.

[0061] Comparative Example 1

[0062] On the basis of Example 1, PEG-200 in the cross-linking monomer a was replaced with MPEG-1200, and other conditions remained unchanged.

[0063] Comparative Example 2

[0064] On the basis of Example 1, the itaconic acid in the cross-linking monomer a was replaced by acrylic acid, and other conditions remained unchanged.

[0065] Comparative Example 3

[0066] On the basis of Example 1, the crosslinking monomer a was replaced by methoxy polyethylene glycol methacrylate (MPEG-1200MAA), and other conditions remained unchanged.

[0067] Comparative Example 4

[0068] On the basis of Example 1, the polyether monomer was replaced with methacrylic polyethylene glycol ether (molecular weight 2400), and other conditions remained unchanged.

[0069] Comparative Example 5

[0070] On the basis of Example 1, the polyether monomer was replaced with isopentenyl polyethylene glycol ether (molecular weight 2400), and other conditions remained unchanged.

[0071] Comparative Example 6

[0072] On the basis of Example 1, (4-vinylphenyl)trimethoxysilane was not added, and other conditions remained unchanged.

[0073] The samples synthesized from Examples 1-5 and Comparative Examples 1-6 were prepared with a concentration of 10%, and Jidong cement was used. The initial slump and expansion of the concrete, as well as the slump and expansion over time and the concrete state were measured according to GB 8076-2008 "Concrete Admixtures". The concrete mix ratio is: cement 260kg / m 3 , fly ash (grade II) 100kg / m 3 、Sand 780kg / m 3 、Stone (5-10mm) 350kg / m 3 、Stone (10-20mm) 640kg / m 3 , montmorillonite 50kg / m 3, water consumption 170kg / m 3 The expansion degree was controlled at 550±10mm. The results are shown in Table 2.

[0074] Table 2 Concrete performance test results

[0075]

[0076] From the test results in Table 2, we can see that:

[0077] The anti-mud and slump-retaining polycarboxylate water-reducing agent provided in Examples 1-5 is applied to concrete, and the test results show that: the dosage in Examples 1-5 is small, and the expansion loss of concrete over time is small. The polycarboxylate water-reducing agent can improve the anti-mud and slump-retaining properties of concrete, reduce the influence of the mud content in the raw materials, and reduce the slump loss during pumping; the compressive strength is slightly higher, the shrinkage ratio is low, and it has excellent effects such as good workability, good wrapping, low viscosity, and fast flow rate; the polycarboxylate water-reducing agent can enhance the anti-mud effect, realize the pumping construction of concrete, and effectively improve the efficiency of concrete construction.

[0078] The water reducer provided in Comparative Example 1 is applied to concrete, and the test results show that: compared with Examples 1-5, its expansion loss over time increases and the flow rate is slow;

[0079] The water reducing agent provided in Comparative Example 2 was applied to concrete, and the test results showed that: compared with Examples 1-5, the workability of the concrete was average, its expansion loss increased over time, and the flow rate was slow;

[0080] The water reducing agent provided in comparative example 3 is applied to concrete, and the test results show that: compared with examples 1-5, the concrete has good workability, its expansion loss increases over time, and the flow rate is average;

[0081] The water reducing agent provided in Comparative Example 4 was applied to concrete, and the test results showed that compared with Examples 1-5, the concrete had average workability, poor encapsulation, and fast flow rate;

[0082] The water reducing agent provided in Comparative Example 5 is applied to concrete, and the test results show that: compared with Examples 1-5, the concrete has better workability and better encapsulation, but a slower flow rate;

[0083] The water reducing agent provided in Comparative Example 6 is applied to concrete, and the test results show that: compared with Examples 1-5, the concrete has good workability, poor encapsulation, but slow flow rate;

[0084] In general, the 28d compressive strength ratio and 28d shrinkage ratio of concrete meet the standard requirements.

[0085] It should be noted that the specific parameters or some reagents in the above embodiments are specific embodiments or preferred embodiments of the present invention, rather than limiting the present invention; those skilled in the art can make adaptive adjustments within the scope of the present invention.

Claims

1. A polycarboxylate water-reducing agent for resisting mud and preventing collapse, characterized in that: In parts by weight, the raw materials for preparing the polycarboxylate water-reducing agent include:

2. The anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 1, characterized in that: The cross-linking monomer includes polyethylene glycol itaconate.

3. The anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 2, characterized in that: In parts by weight, the raw materials for preparing the polyethylene glycol itaconate include:

4. The anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 1, characterized in that: The unsaturated sulfonic acid monomer includes at least one of 2-acrylamide 2-methylpropane sulfonic acid and sodium methyl propene sulfonate.

5. The anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 1, characterized in that: The rigid unsaturated monomer includes (4-vinylphenyl)trimethoxysilane.

6. The anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 1, characterized in that: The polyether macromonomer includes ethylene glycol monovinyl ether polyoxyethylene ether, and the molecular weight of the ethylene glycol monovinyl ether polyoxyethylene ether is 1000-3000.

7. A method for preparing the anti-mud collapse-preserving polycarboxylate water-reducing agent according to any one of claims 1 to 6, characterized in that: Includes steps: Dissolving the polyether macromonomer in water to obtain a solution to obtain a base material; Add material A and material B dropwise to the base material, react at a constant temperature after the addition is complete, and adjust the pH to 5 to 7 after the reaction is complete to obtain an anti-mud and collapse-preserving water-reducing agent; Wherein, the material A is a mixed solution obtained by dissolving unsaturated acid, cross-linking monomer, unsaturated sulfonic acid monomer, rigid unsaturated monomer and chain transfer agent in water; The material B is a solution obtained by dissolving a reducing agent in water.

8. The method for preparing the anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 7, characterized in that: The preparation steps of the polyethylene glycol itaconate are as follows: Itaconic acid, hydroquinone and p-toluenesulfonic acid are added to polyethylene glycol for reaction, and polyethylene glycol itaconic acid ester is obtained after the reaction is completed.

9. The method for preparing the anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 8, characterized in that: The reaction temperature is 80-100°C.

10. The method for preparing the anti-mud collapse-preserving polycarboxylate water-reducing agent according to claim 8, characterized in that: The reaction time is 2h~4h.

Images