Early-strength water reducing agent and preparation method thereof

Abstract

The invention belongs to the field of application and utilization of concrete admixtures, and discloses an early-strength water reducing agent and a preparation method thereof, and the early-strength water reducing agent is prepared from the following raw materials in percentage by mass: 5-10% of early-strength polycarboxylic acid water reducing agent mother liquor, 5-10% of inorganic early-strength agent, 2-5% of organic early-strength agent, 0.5-1% of suspension stabilizer and 74-87.5% of water. The prepared early-strength water reducing agent is in an emulsion state, does not contain chloride ions, is not easy to layer, is convenient to use, has an obvious concrete early strength effect, does not shrink in later strength, has the advantages of simple preparation process, low cost and small mixing amount, is generally 1-2% of the mass of a concrete cementing material, can improve the workability of premixed concrete, and can improve the concrete early strength. The early strength of the concrete is improved, and the long-term strength of the concrete is not influenced.

Description

Technical Field

[0001] The invention belongs to the field of application and utilization of concrete admixtures, and more specifically, relates to an early strength water reducing agent and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology and urbanization, the construction and building materials industry has ushered in an unprecedented period of growth. Precast concrete components are gradually becoming the new favorite of the construction industry because they can improve production efficiency, ensure product quality, and comply with the concept of sustainable social development. This factory prefabrication and assembly construction method not only speeds up the progress of concrete construction and shortens the construction period, but also enables faster turnover of modules during construction, thereby improving overall efficiency. However, in order to further improve turnover efficiency, higher requirements are placed on the early strength of precast concrete.

[0003] In traditional concrete, water-reducing agent is added to reduce the water-cement ratio and thus improve the concrete performance. Early-strength water-reducing agent goes a step further on this basis. It can not only effectively reduce the water-cement ratio, but also reduce the difficulty of cement hydration, shorten the initial setting and final setting time, and thus significantly improve the early strength of concrete. This characteristic plays an important role in improving the turnover efficiency of precast concrete components, reducing mold occupancy rate, and improving production efficiency and economic benefits. Therefore, the application prospects of early-strength water-reducing agent in the construction industry are extremely broad and have become the focus of research at home and abroad.

[0004] However, the existing early strength water reducers still have some shortcomings in preparation and application. For example, common inorganic salt early strength water reducers have an effect on improving the early strength of concrete, but they are restricted in use because they usually contain chloride ions, which easily cause steel corrosion. Alcoholamine early strength water reducers are not widely used because of their high cost. In addition, traditional composite early strength water reducers often contain chloride salts and sulfates, which often cause alkali aggregate reaction.

[0005] To this end, the present invention provides an early strength water reducing agent and a preparation method thereof. Summary of the invention

[0006] In view of the above-mentioned problems existing in the prior art, the object of the present invention is to provide an early-strength water-reducing agent and a preparation method thereof. The early-strength water-reducing agent is in an emulsion state, does not contain chloride ions, is not easy to stratify, is easy to use, has obvious early strength effect on concrete, and does not shrink in later strength. It also has the advantages of simple preparation process, low cost, and small dosage, which is generally 1% to 2% of the mass of concrete cementitious materials. It can improve the workability of ready-mixed concrete, increase the early strength of concrete, and does not affect the functional characteristics of the later strength of concrete.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] An early-strength water reducer is prepared from raw materials in the following mass fraction ratios:

[0009] 5% - 10% of early-strength polycarboxylate water reducer mother liquor, 5% - 10% of inorganic early-strengthening agent, 2% - 5% of organic early-strengthening agent, 0.5% - 1% of suspension stabilizer, and 74% - 87.5% of water.

[0010] As a further preferred technical solution of the present invention, the early-strength polycarboxylate water reducer mother liquor is prepared by polymerization from raw materials including the following parts by mass:

[0011] 300 - 400 parts of ethylene glycol mono vinyl polyethylene glycol ether, 5 - 15 parts of maleic anhydride, and 10 - 15 parts of acrylic acid or acrylic acid derivative.

[0012] As a further preferred technical solution of the present invention, the general formula of the ethylene glycol mono vinyl polyethylene glycol ether is as follows:

[0013]

[0014] In the general formula of the ethylene glycol mono vinyl polyethylene glycol ether, n = 50 - 100.

[0015] As a further preferred technical solution of the present invention, the acrylic acid derivative is hydroxyethyl acrylate.

[0016] As a further preferred technical solution of the present invention, the inorganic early-strengthening agent is one of calcium formate, magnesium acetate, and nano-silica; or, the inorganic early-strengthening agent is a composite of calcium formate, magnesium acetate, and nano-silica.

[0017] As a further preferred technical solution of the present invention, the organic early-strengthening agent is one of triethanolamine and diethanol monoisopropanolamine; or, the organic early-strengthening agent is a composite of triethanolamine and diethanol monoisopropanolamine.

[0018] As a further preferred technical solution of the present invention, the suspension stabilizer is magnesium aluminum silicate hydrate, and the molecular formula of the magnesium aluminum silicate hydrate is as follows:

[0019] (Mg·Al)5Si8O20·4H2O.

[0020] A preparation method of an early-strength water reducer, and the early-strength water reducer is prepared by the following steps and methods:

[0021] Add a certain amount of water to a wide-mouth bottle, start stirring, add a suspension stabilizer, and configure it into a concentration of 4-6%. Using a disperser, shear it at a speed of 1800-2200 revolutions per second for 10 minutes to obtain a paste-like form. Then, reduce the speed to 490-510 revolutions per second and add water, an inorganic early-strength agent, an organic early-strength agent, and an early-strength polycarboxylate superplasticizer mother liquor, and stir until completely dissolved to obtain an early-strength superplasticizer with a mass concentration of 12.5%-17.5%.

[0022] As a further preferred technical solution of the present invention, the early-strength polycarboxylate superplasticizer mother liquor is prepared by the following steps and methods:

[0023] (1) First, dissolve ethylene glycol monovinyl polyethylene glycol ether and maleic anhydride at 80-100 °C and carry out an esterification reaction for 5-10 hours to obtain an esterification monomer, and its general formula is as follows:

[0024]

[0025] (2) Then, mix the esterification monomer, acrylic acid or acrylic acid derivative, sodium hypophosphite, and water evenly to prepare a bottom liquid;

[0026] (3) Finally, add an oxidant, a reductant, and a catalyst, and carry out a polymerization reaction at room temperature;

[0027] Among them, the oxidant is selected from hydrogen peroxide or ammonium persulfate, the reductant is selected from L-ascorbic acid or sodium bisulfite, and the catalyst is selected from ferrous sulfate.

[0028] As a further preferred technical solution of the present invention, the oxidant is directly added to the bottom liquid, the reductant and the catalyst are formulated into a dropping liquid, and the dropping is completed within 0.5-3 hours. After the dropping is completed, continue to age for 1 hour and then add water to a mass concentration of 35%-45% to finally obtain an early-strength polycarboxylate superplasticizer mother liquor.

[0029] As described above, an early-strength superplasticizer and its preparation method provided by the present invention have the following beneficial effects:

[0030] The present invention utilizes the above-mentioned early-strength water reducer and its preparation method. Compared with the prior art, the present invention adopts the solution free radical polymerization method. The macromonomer used is a polyether macromonomer with a specific molecular weight of about 8000. The polymerization monomers are small monomers such as acrylic acid and hydroxyethyl acrylate. Through the free radical initiation polymerization reaction, a super early-strength polycarboxylate water reducer mother liquor is prepared. In order to ensure that more inorganic early-strength agents can be compounded and dissolved without delamination, a suspension stabilizer is added, which can ensure the stability and non-delamination after compounding. The early-strength water reducer prepared by this method is in an emulsion state, does not contain chloride ions, is not easy to delaminate, is convenient to use, has obvious early strength effect on concrete, does not show a reverse shrinkage in later strength, and has the functional characteristics of simple preparation process, low cost, small dosage (generally the dosage is 1% - 2% of the mass of the concrete binder), can improve the workability of ready-mixed concrete, increase the early strength of concrete, and does not affect the later strength of concrete.

[0031] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. Detailed Embodiments

[0032] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0034] The present invention provides an early-strength water reducer and its preparation method. The early-strength water reducer is prepared from raw materials with the following mass fraction ratios:

[0035] Early-strength polycarboxylate water reducer mother liquor 5% - 10%, inorganic early-strength agent 5% - 10%, organic early-strength agent 2% - 5%, suspension stabilizer 0.5% - 1%, and water 74% - 87.5%.

[0036] The early-strength polycarboxylate water reducer mother liquor is prepared by polymerization from raw materials including the following mass parts:

[0037] Ethylene glycol mono vinyl polyethylene glycol ether 300 - 400 parts, maleic anhydride 5 - 15 parts, acrylic acid or acrylic acid derivative 10 - 15 parts.

[0038] The general formula of the ethylene glycol mono vinyl polyethylene glycol ether is as follows:

[0039]

[0040] In the general formula of the ethylene glycol mono vinyl polyethylene glycol ether, n = 50 - 100. In this embodiment, preferably n = 60 - 80.

[0041] The acrylic derivative described above is hydroxyethyl acrylate.

[0042] The inorganic early strength agent is one of calcium formate, magnesium acetate, and nano-silica; or, the inorganic early strength agent is a composite of calcium formate, magnesium acetate, and nano-silica; in this embodiment, it is preferably a composite of calcium formate, magnesium acetate, and nano-silica.

[0043] The organic early strength agent is one of triethanolamine and diethanol monoisopropanolamine; or, the organic early strength agent is a composite of triethanolamine and diethanol monoisopropanolamine; in this embodiment, it is preferably a composite of triethanolamine and diethanol monoisopropanolamine.

[0044] The suspension stabilizer is magnesium aluminum silicate hydrate, and the molecular formula of the magnesium aluminum silicate hydrate is as follows:

[0045] (Mg·Al) 5 Si 8 O 20 ·4H 2 O.

[0046] A preparation method of an early strength water reducing agent, and the early strength water reducing agent is prepared by the following steps and methods:

[0047] Add a certain amount of water to a wide-mouth bottle, start stirring, add the suspension stabilizer, and configure it into a concentration of 4-6%, preferably 5% in this embodiment. Use a disperser to shear for 10 minutes at a speed of 1800-2200 revolutions per second, preferably 2000 revolutions per second in this embodiment, to obtain a paste form. Then reduce the speed to 490-510 revolutions per second and add water, inorganic early strength agent, organic early strength agent, and early strength polycarboxylate water reducing agent mother liquor. Preferably reduce the speed to 500 revolutions per second and add water, inorganic early strength agent, organic early strength agent, and early strength polycarboxylate water reducing agent mother liquor in this embodiment, and stir until completely dissolved to obtain an early strength water reducing agent with a mass concentration of 12.5%-17.5%, preferably 15% in this embodiment.

[0048] The early strength polycarboxylate water reducing agent mother liquor is prepared by the following steps and methods:

[0049] (1) First, dissolve ethylene glycol monovinyl polyethylene glycol ether and maleic anhydride at 80-100 °C and carry out an esterification reaction for 5-10 hours, preferably 6-8 hours in this embodiment, to obtain an esterification monomer, and its general formula is as follows:

[0050]

[0051] (2) Next, mix the esterifying monomer, acrylic acid or acrylic acid derivative, sodium hypophosphite and water evenly to prepare a bottom liquid;

[0052] (3) Finally, add an oxidizing agent, a reducing agent and a catalyst, and carry out a polymerization reaction at room temperature;

[0053] Among them, the oxidizing agent is selected from hydrogen peroxide or ammonium persulfate, the reducing agent is selected from L-ascorbic acid or sodium bisulfite, and the catalyst is selected from ferrous sulfate.

[0054] The oxidizing agent is directly added to the bottom liquid. The reducing agent and the catalyst need to be prepared into a dropping solution and dropped within 0.5 - 3 hours. In this embodiment, it is preferably dropped within 1 - 1.5 hours. After dropping, continue aging for 1 hour and then add water to make the mass concentration reach 35% - 45%. In this embodiment, it is preferably added water to make the mass concentration reach 40%, and finally an early-strength polycarboxylate superplasticizer mother liquor is obtained.

[0055] Specifically, the preparation examples of the early-strength polycarboxylate superplasticizer mother liquor and the early-strength superplasticizer are as follows:

[0056] Preparation example of the early-strength polycarboxylate superplasticizer mother liquor:

[0057] First, add 350 g of ethylene glycol mono vinyl polyethylene glycol ether and 10 g of maleic anhydride, heat them in a water bath to about 90 °C, and carry out an esterification reaction for 6 hours. After the esterification reaction is completed, add 300 g of water, 5 g of acrylic acid, 5 g of hydroxyethyl acrylate, 5 g of sodium hypophosphite, and 2 g of hydrogen peroxide to the container and stir to dissolve. Dissolve 0.01 g of ferrous sulfate and 0.5 g of L-ascorbic acid in 50 g of water as a dropping solution. After complete dissolution, start dropping and finish dropping within 1 hour. After dropping, continue the reaction for 1 hour and add water to make the mass concentration reach about 40% to obtain an early-strength polycarboxylate superplasticizer mother liquor.

[0058] Preparation example 1 of the early-strength superplasticizer:

[0059] Add 790 g of water to a wide-mouth bottle, start stirring, add 20 g of calcium formate, 20 g of magnesium acetate, 50 g of nano-silica, 10 g of triethanolamine, 10 g of diethanol monoisopropanolamine, and 100 g of a common polycarboxylate superplasticizer mother liquor, and stir until completely dissolved to obtain an early-strength superplasticizer.

[0060] Preparation example 2 of the early-strength superplasticizer:

[0061] Add 790 g of water to a wide-mouth bottle, start stirring, add 20 g of calcium formate, 20 g of magnesium acetate, 50 g of nano-silica, 10 g of triethanolamine, 10 g of diethanol monoisopropanolamine, and 100 g of an early-strength polycarboxylate superplasticizer mother liquor, and stir until completely dissolved to obtain an early-strength superplasticizer.

[0062] Example 3 for preparing early-strength water reducer:

[0063] Add 900 g of water into a wide-mouth bottle, start stirring, add 100 g of early-strength polycarboxylate water reducer mother liquor, and stir until completely dissolved to obtain an early-strength water reducer.

[0064] Example 4 for preparing early-strength water reducer:

[0065] Add 100 g of water into a wide-mouth bottle, start stirring, add 5 g of suspension stabilizer, and use a disperser to shear for 10 minutes at a speed of about 2000 revolutions per second to obtain a paste form. Then reduce the speed to about 500 revolutions per second and add water, 20 g of calcium formate, 20 g of magnesium acetate, 50 g of nano-silica, 10 g of triethanolamine, 10 g of diethanol monoisopropanolamine, and 100 g of early-strength polycarboxylate water reducer mother liquor, and stir until completely dissolved to obtain an early-strength water reducer.

[0066] Application example:

[0067] For the early-strength water reducers prepared in Examples 1 - 4 of the early-strength water reducer, according to the test method in GB 8076-2008 "Concrete Admixtures", add an early-strength water reducer with a dosage of 2% to conduct a compressive strength ratio test on these 4 samples, and observe the appearance of the water reducer after standing for 28 days. The test results are shown in Table 1.

[0068] Table 1 - Test results

[0069]

[0070] As can be seen from Table 1, by comparing Examples 1 and 2, it can be found that the early-strength water reducer mother liquor has better early strength than the ordinary water reducer mother liquor. By comparing Examples 2 and 3, adding inorganic and organic early-strength agents can also significantly improve the early strength of concrete. From the solution stability of these 4 examples, it can be seen that adding early-strength agents easily causes the water reducer to stratify, and the suspension stabilizer can well solve the problem of stratification.

[0071] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

Claims

1. An early strength water reducing agent, characterized in that: Prepared from raw materials containing the following mass fraction ratios: The early strength type polycarboxylate water-reducing agent mother liquor is 5% to 10%, the inorganic early strength agent is 5% to 10%, the organic early strength agent is 2% to 5%, the suspension stabilizer is 0.5% to 1% and the water is 74% to 87.5%.

2. An early strength water reducing agent according to claim 1, characterized in that: The early-strength polycarboxylate water-reducing agent mother solution is prepared by polymerizing the following raw materials in parts by weight: 300-400 parts of ethylene glycol monovinyl polyglycol ether, 5-15 parts of maleic anhydride, and 10-15 parts of acrylic acid or acrylic acid derivatives.

3. An early strength water reducing agent according to claim 2, characterized in that: The general formula of the ethylene glycol monovinyl polyglycol ether is as follows: In the general formula of the ethylene glycol monovinyl polyglycol ether, n=50-100.

4. An early strength water reducing agent according to claim 2, characterized in that: The acrylic acid derivative is hydroxyethyl acrylate.

5. An early strength water reducing agent according to claim 1, characterized in that: The inorganic early strength agent is one of calcium formate, magnesium acetate and nano silicon dioxide; or the inorganic early strength agent is a composite of calcium formate, magnesium acetate and nano silicon dioxide.

6. The early strength water reducing agent according to claim 1, characterized in that: The organic early strength agent is one of triethanolamine and diethanol monoisopropanolamine; or the organic early strength agent is a composite of triethanolamine and diethanol monoisopropanolamine.

7. The early strength water reducing agent according to claim 1, characterized in that: The suspension stabilizer is hydrated magnesium aluminum silicate, and the molecular formula of the hydrated magnesium aluminum silicate is as follows: (Mg·Al)5Si8O 20 ·4H2O。 8. A method for preparing an early strength water reducing agent, characterized in that: The early strength water reducing agent is prepared by the following steps and methods: Add a certain amount of water to a wide-mouth bottle, start stirring, add a suspension stabilizer, and prepare it to a concentration of 4-6%. Use a disperser to shear for 10 minutes at a speed of 1900-2100 rpm to disperse it into a paste form, then reduce the speed to 450-550 rpm, add water, inorganic early strength agent, organic early strength agent and early strength type polycarboxylate water reducer mother liquor, stir until completely dissolved to obtain an early strength type water reducer with a mass concentration of 14%-16%.

9. The method for preparing an early strength water reducing agent according to claim 8, characterized in that: The early-strength polycarboxylate water-reducing agent mother solution is prepared by the following steps and methods: (1) First, ethylene glycol monovinyl polyethylene glycol ether and maleic anhydride are melted at 80-100 degrees Celsius and subjected to esterification reaction for 5-10 hours to obtain an esterified monomer, the general formula of which is shown below: (2) Next, the esterification monomer, acrylic acid or acrylic acid derivative, sodium hypophosphite and water are uniformly mixed to prepare a base liquid; (3) Finally, an oxidant, a reducing agent and a catalyst are added, and a polymerization reaction is carried out at room temperature; Wherein, the oxidant is selected from hydrogen peroxide or ammonium persulfate, the reducing agent is selected from L-ascorbic acid or sodium bisulfite, and the catalyst is selected from ferrous sulfate.

10. The method for preparing an early strength water reducing agent according to claim 9, characterized in that: The oxidant is directly added to the base liquid, the reductant and the catalyst are prepared into a drop solution, and the drop addition is completed within 0.5-3 hours. After the drop addition is completed, the solution is aged for 1 hour and then water is added to a mass concentration of 35%-45%, and finally an early strength polycarboxylate water-reducing agent mother solution is obtained.

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