Early strength water reducing agent and preparation method thereof

Abstract

The application relates to an early-strength water-reducing agent and a preparation method thereof, which comprises the following raw materials in proportion by weight: 25-36 parts of polyether macromonomer, 3-7 parts of unsaturated acid, 0.05-0.2 parts of initiator, 0.08-0.26 parts of chain transfer agent, 2-4 parts of pH regulator, 10-18 parts of early-strength monomer, and 42-58 parts of water. The early-strength water-reducing agent has good water-reducing performance, good dispersibility when added in concrete, and can greatly improve the early compressive strength of the concrete, has no influence on the later strength of the concrete, and can effectively shorten the construction progress of the concrete in winter.

Description

Technical Field

[0001] This invention relates to the field of concrete admixtures, specifically to an early-strength water-reducing agent and its preparation method. Background Technology

[0002] With the increasing use of concrete, the demand for concrete water-reducing agents is also increasing. Although adding ordinary concrete water-reducing agents to concrete can improve the compressive strength, it also prolongs the setting time and results in low early strength. Some special precast concretes, such as pipe piles and pipe segments, require high early strength, which can shorten the construction time. In winter, when the outside temperature is too low, the setting time of concrete is even longer, and it may even take two or three days to develop strength. Concrete is easily damaged by freezing, which seriously affects the quality of concrete and the construction progress.

[0003] To meet the special early strength requirements of concrete and ensure the quality and construction progress of concrete in winter, water-reducing agents are needed to improve the early strength of concrete. Currently, synthetic early-strength water-reducing agents on the market include naphthalene-based, melamine-based, and aliphatic water-reducing agents. The production of these agents is relatively dangerous due to the use of concentrated sulfuric acid, formaldehyde, acetone, etc., as raw materials, and they are also environmentally harmful. They have low water-reducing rates, poor dispersibility in concrete, and low early strength. In addition to synthetic water-reducing agents, the market also utilizes compounded organic early-strength agents such as triethanolamine, diethanolamine, and ethanolamine to improve the early strength of concrete. Early strength agents of this type have poor early strength effect, and excessive addition can lead to rapid setting of concrete and reduced durability. In the market, compound inorganic early strength agents such as aluminum fluorosilicate, water glass, sodium sulfate, and sodium nitrate are also used to improve the early strength of concrete. However, these early strength agents have poor solubility, which has a significant impact on the water reduction rate of water-reducing agents and greatly reduces the later strength of concrete. This invention uses a synthetic early strength monomer and grafts it onto the polycarboxylic acid molecular structure to prepare an early strength water-reducing agent with high water reduction rate, good dispersibility, high early strength, and no impact on the later strength of concrete, effectively ensuring concrete quality and shortening the construction progress. Summary of the Invention

[0004] In view of the prior art, the present invention develops an early-strength water-reducing agent and its preparation method. The early-strength water-reducing agent prepared by the invention can increase the fluidity of concrete, improve the early compressive strength of concrete, and does not affect the later compressive strength of concrete.

[0005] Based on this, the present invention provides an early-strength water-reducing agent, comprising the following raw materials by weight: 25-36 parts of polyether macromonomer, 3-7 parts of unsaturated acid, 0.05-0.2 parts of initiator, 0.08-0.26 parts of chain transfer agent, 2-4 parts of pH adjuster, 10-18 parts of early-strength monomer, and 42-58 parts of water.

[0006] Furthermore, the raw materials for the early-strength monomer, by weight, include 36-48 parts of organic aluminum alkoxide, 50-65 parts of acid anhydride, and 0.2-0.8 parts of catalyst.

[0007] Furthermore, the organic aluminum alkoxide includes at least one of aluminum ethoxide, aluminum diethylethoxide, aluminum propoxide, aluminum isopropoxide, aluminum isopropoxide dimethyl aluminum, aluminum n-butoxide, aluminum isobutoxide, and aluminum pentaerythritol.

[0008] Further, the acid anhydride includes at least one of acrylic anhydride, butenoic anhydride, butenediic anhydride, pentenoic anhydride, pentenediic anhydride, hexenoic anhydride, cyclohexenoic anhydride, and hexenediic anhydride.

[0009] Furthermore, the catalyst includes at least one of sulfuric acid and phosphoric acid.

[0010] Furthermore, the method for preparing the early-strength monomer is as follows: the organic aluminum alkoxide is added to the reactor, the temperature is raised to 95℃~120℃, the acid anhydride and the catalyst are added, and the temperature is maintained for 6~8h.

[0011] Furthermore, the polyether macromonomer is isopentenyl alcohol polyoxyethylene ether, with a molecular weight of 5000-6000.

[0012] Furthermore, the unsaturated acid includes at least one of acrylic acid, maleic acid, and itaconic acid.

[0013] Further, the initiator includes at least one of ammonium persulfate, potassium persulfate, sodium persulfate, and hydrogen peroxide; the chain transfer agent includes at least one of fatty alcohol thiols, dodecyl mercaptan, isopropanol, sodium bisulfite, mercaptoethanol, mercaptoacetic acid, mercaptopropanol, mercaptopropionic acid, and sodium hypophosphite; and the pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0014] A second objective of this invention is to provide a method for preparing an early-strength water-reducing agent, comprising the following steps:

[0015] Add 25-36 parts of polyether macromonomer and 30-38 parts of water to the reactor, and heat to 60-70℃;

[0016] After the polyether macromonomers are dissolved, the first mixture is added, and the second and third mixtures are added dropwise at the same time; after the second and third mixtures are added, the temperature is maintained for 1 to 2 hours; then 2 to 4 parts of pH adjuster are added to obtain the early strength water-reducing agent.

[0017] The first mixture is a mixture of 3-7 parts of unsaturated acid and 10-18 parts of early-strength monomer; the second mixture is a mixture of 0.05-0.2 parts of initiator and 6-10 parts of water; and the third mixture is a mixture of 0.08-0.26 parts of chain transfer agent and 6-10 parts of water.

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

[0019] This invention prepares an early-strength water-reducing agent by grafting a synthesized early-strength monomer onto the polycarboxylic acid molecular structure. This early-strength water-reducing agent has a high water reduction rate, good dispersibility, high early strength, and does not affect the later strength of concrete, effectively ensuring concrete quality and shortening the construction schedule. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials and reagents used in the following examples are commercially available. All quantitative experiments in the following examples were performed in triplicate, and the data are the average of the three replicates or the average ± standard deviation.

[0022] Furthermore, the term "and / or" in the text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that simultaneously satisfies both A and B. In addition, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] The technical solution of the present invention will be further described below with reference to preferred embodiments.

[0024] Example 1

[0025] An early-strength water-reducing agent, the required raw materials are as follows, by weight:

[0026] Isopentenyl alcohol polyoxyethylene ether with a molecular weight of 5000: 32 parts;

[0027] Acrylic acid: 3 parts;

[0028] Ammonium persulfate: 0.08 parts;

[0029] Mercaptoethanol: 0.12 parts;

[0030] Sodium hydroxide: 2 parts;

[0031] Early-strength monomer: 12.8 parts;

[0032] Deionized water: 50 parts.

[0033] The preparation method of the early-strength water-reducing agent includes the following steps:

[0034] Add 35 parts of deionized water and 32 parts of isopentenyl alcohol polyoxyethylene ether to the reaction flask, and raise the temperature to 60°C.

[0035] After the isopentenyl alcohol polyoxyethylene ether is dissolved, the first mixture is added, and the second and third mixtures are added dropwise at the same time; after the second and third mixtures are added, the temperature is maintained for 1 hour; then 2 parts of sodium hydroxide are added to obtain the early strength water-reducing agent.

[0036] The first mixture consists of 3 parts acrylic acid and 12.8 parts early-strength monomer;

[0037] The second mixture was obtained by mixing 0.08 parts ammonium persulfate and 7.5 parts deionized water in a beaker, and the second mixture was added dropwise over 3 hours.

[0038] The third mixture was obtained by mixing 0.12 parts mercaptoethanol and 7.5 parts deionized water in a beaker, and the third mixture was added dropwise over a period of 3 hours.

[0039] The preparation method of the early-strength monomer is as follows: 38 parts of aluminum ethoxide are added to the reactor and the temperature is raised to 95°C; then 61.8 parts of acrylic anhydride and 0.2 parts of sulfuric acid are added, and the mixture is kept at this temperature for 8 hours to prepare the early-strength monomer.

[0040] Example 2

[0041] An early-strength water-reducing agent, the required raw materials are as follows, by weight:

[0042] Isopentenyl alcohol polyoxyethylene ether with a molecular weight of 5000: 33 parts;

[0043] Acrylic acid: 3 parts;

[0044] Ammonium persulfate: 0.10 parts;

[0045] Mercaptoethanol: 0.15 parts;

[0046] Sodium hydroxide: 2 parts;

[0047] Early-strength monomer: 11.75 parts;

[0048] Deionized water: 50 parts.

[0049] The preparation method of the early-strength water-reducing agent includes the following steps:

[0050] Add 34 parts of deionized water and 33 parts of isopentenyl alcohol polyoxyethylene ether to the reaction flask, and raise the temperature to 60°C.

[0051] After the polyether macromonomers are dissolved, the first mixture is added, while the second and third mixtures are added dropwise. After the second and third mixtures are added, the mixture is kept warm for 1 hour. Then, 2 parts of sodium hydroxide are added to obtain the early-strength water-reducing agent.

[0052] The first mixture consists of 3 parts acrylic acid and 11.75 parts early-strength monomer;

[0053] The second mixture was obtained by mixing 0.10 parts ammonium persulfate and 8 parts deionized water in a beaker, and the second mixture was added dropwise over 3 hours.

[0054] The third mixture was obtained by mixing 0.15 parts mercaptoethanol and 8 parts deionized water in a beaker, and the third mixture was added dropwise over a period of 3 hours.

[0055] The preparation method of the early-strength monomer is as follows: 38 parts of diethylethoxide aluminum are added to a reactor and the temperature is raised to 95°C; then 61.6 parts of butenoic anhydride and 0.4 parts of sulfuric acid are added, and the mixture is kept at this temperature for 8 hours to prepare the early-strength monomer.

[0056] Example 3

[0057] An early-strength water-reducing agent, the required raw materials are as follows, by weight:

[0058] Isopentenyl alcohol polyoxyethylene ether with a molecular weight of 5000: 30 parts;

[0059] Itaconic acid: 6 parts;

[0060] Potassium persulfate: 0.15 parts;

[0061] Thioglycolic acid: 0.08 parts;

[0062] Potassium hydroxide: 3 parts;

[0063] Early-strength monomer: 10.77 parts;

[0064] Deionized water: 50 parts.

[0065] The preparation method of the early-strength water-reducing agent includes the following steps:

[0066] Add 30 parts of deionized water and 30 parts of isopentenyl alcohol polyoxyethylene ether to the reaction flask, and raise the temperature to 60°C.

[0067] After the polyether macromonomer is dissolved, the first mixture is added, and the second and third mixtures are added dropwise at the same time; after the second and third mixtures are added, the temperature is maintained for 2 hours; then 3 parts of potassium hydroxide are added to obtain the early-strength water-reducing agent.

[0068] The first mixture consists of 6 parts itaconic acid and 10.77 parts early-strength monomer;

[0069] The second mixture was obtained by mixing 0.15 parts potassium persulfate and 10 parts deionized water in a beaker, and the second mixture was added dropwise over 3 hours.

[0070] The third mixture was obtained by mixing 0.08 parts mercaptoacetic acid and 10 parts deionized water in a beaker, and the third mixture was added dropwise over a period of 3 hours.

[0071] The preparation method of the early-strength monomer is as follows: 40 parts of aluminum propoxide are added to a reactor and the temperature is raised to 100℃; then 59.4 parts of pentene anhydride and 0.6 parts of phosphoric acid are added, and the mixture is kept at this temperature for 8 hours to prepare the early-strength monomer.

[0072] Example 4

[0073] An early-strength water-reducing agent, the required raw materials are as follows, by weight:

[0074] Isopentenyl alcohol polyoxyethylene ether with a molecular weight of 5000: 28 parts;

[0075] Maleic acid: 6 parts;

[0076] Sodium persulfate: 0.06 parts;

[0077] Mercaptopropanol: 0.15 parts;

[0078] Potassium hydroxide: 2 parts;

[0079] Early-strength monomer: 13.79 parts;

[0080] Deionized water: 50 parts.

[0081] The preparation method of the early-strength water-reducing agent includes the following steps:

[0082] Add 38 parts of deionized water and 28 parts of isopentenyl alcohol polyoxyethylene ether to the reaction flask, and raise the temperature to 60°C.

[0083] After the polyether macromonomer is dissolved, the first mixture is added, and the second and third mixtures are added dropwise at the same time; after the second and third mixtures are added, the temperature is maintained for 2 hours; then 2 parts of potassium hydroxide are added to obtain the early-strength water-reducing agent.

[0084] The first mixture consists of 6 parts maleic acid and 13.79 parts early-strength monomer;

[0085] The second mixture was obtained by mixing 0.06 parts sodium persulfate and 6 parts deionized water in a beaker, and the second mixture was added dropwise over 3 hours.

[0086] The third mixture was obtained by mixing 0.15 parts mercaptopropanol and 6 parts deionized water in a beaker, and the third mixture was added dropwise over a period of 3 hours.

[0087] The preparation method of the early-strength monomer is as follows: 42 parts of aluminum isopropoxide are added to a reactor and the temperature is raised to 100℃; then 57.4 parts of butenedioic anhydride and 0.6 parts of sulfuric acid are added, and the mixture is kept at this temperature for 8 hours to prepare the early-strength monomer.

[0088] Example 5

[0089] An early-strength water-reducing agent, the required raw materials are as follows, by weight:

[0090] Isopentenyl alcohol polyoxyethylene ether with a molecular weight of 6000: 25 parts;

[0091] Acrylic acid: 5 parts;

[0092] Hydrogen peroxide: 0.2 parts;

[0093] Sodium hypophosphite: 0.22 parts;

[0094] Lithium hydroxide: 3 parts;

[0095] Early-strength monomer: 16.58 parts;

[0096] Deionized water: 50 parts.

[0097] The preparation method of the early-strength water-reducing agent includes the following steps:

[0098] Add 38 parts of deionized water and 25 parts of isopentenyl alcohol polyoxyethylene ether to the reaction flask, and raise the temperature to 60°C.

[0099] After the polyether macromonomer is dissolved, the first mixture is added, and the second and third mixtures are added dropwise at the same time; after the second and third mixtures are added, the temperature is maintained for 1 hour; then 3 parts of lithium hydroxide are added to obtain the early-strength water-reducing agent.

[0100] The first mixture consists of 5 parts acrylic acid and 16.58 parts early-strength monomer;

[0101] The second mixture was obtained by mixing 0.2 parts hydrogen peroxide and 6 parts deionized water in a beaker, and the second mixture was added dropwise over 3 hours.

[0102] The third mixture was obtained by mixing 0.22 parts sodium hypophosphite and 6 parts deionized water in a beaker, and the third mixture was added dropwise over a period of 3 hours.

[0103] The preparation method of the early-strength monomer is as follows: 44 parts of aluminum isobutoxide are added to a reactor and the temperature is raised to 110℃; then 55.4 parts of cyclohexenoic anhydride and 0.6 parts of phosphoric acid are added, and the mixture is kept at this temperature for 8 hours to prepare the early-strength monomer.

[0104] Performance evaluation

[0105] Using a commercially available conventional early-strength polycarboxylate superplasticizer (PE) as Comparative Example 1, performance tests were conducted on the early-strength superplasticizers of Examples 1-5 of the present invention and Comparative Example 1.

[0106] (1) Experimental materials

[0107] Cement: Conch Cement P.O42.5;

[0108] Sand: Manufactured sand, fineness modulus 2.2, mud content 3.5%;

[0109] Gravel: particle size 5mm~10mm, mud content 0.2%, crushing value 12.6%;

[0110] Comparative example: Commercially available traditional polycarboxylate superplasticizer (PE), with a solid content of 10%;

[0111] (2) Concrete mix proportion

[0112] The proportions of concrete raw materials are shown in Table 1:

[0113] Table 1 Concrete mix proportions (unit: kg / m³) 3 )

[0114] raw materials cement sand pebbles water Water reducing agent Dosage 360 1050 880 155 5.4

[0115] The early-strength water-reducing agents obtained in Examples 1 to 5 were compounded into samples with a solid content of 10%. Then, the samples obtained in Examples 1 to 5 and Comparative Example 1 were mixed according to the mix proportions in Table 1. The concrete slump / spread (mm / mm) evaluation results are shown in Table 2.

[0116] Table 2. Results of Concrete Slump / Spreadability Assessment

[0117]

[0118] As shown in Table 2, the initial slump / spread of the concrete without water-reducing agent was 180mm / 420mm, and it lost its fluidity after 1 hour. The initial slump / spread of the concrete with commercially available traditional polycarboxylate water-reducing agent was 200mm / 510mm, and the slump / spread after 1 hour was 160mm / 410mm, with a slump / spread loss of 40mm / 100mm, which is quite significant. For concrete with the early-strength water-reducing agent in Examples 1-5 of this invention, the initial slump / spread is greater than 210mm / 520mm, and the slump / spread after 1 hour is greater than 180mm / 430mm. In particular, the concrete with the early-strength water-reducing agent in Example 4 has a slump / spread of 220mm / 560mm and a slump / spread of 205mm / 510mm after 1 hour, with a small loss of slump / spread. The slump / spread loss in Example 4 is 15mm / 50mm, which indicates that the concrete has the best slump retention performance.

[0119] As can be seen from the above, the concrete with the early-strength water-reducing agent in Examples 1 to 5 of the present invention has better fluidity and slump retention compared with the concrete without water-reducing agent and the concrete with commercially available early-strength polycarboxylate water-reducing agent.

[0120] To further illustrate the early strength effect of this early-strength water-reducing agent, the above concrete was molded and strength tests were conducted at 1d, 3d, 7d, and 28d. The concrete strength test results are shown in Table 3.

[0121] Table 3 Comparison of Concrete Strength

[0122]

[0123]

[0124] As shown in Table 3, after adding commercially available water-reducing agent, the compressive strength of concrete increased by 4.8 MPa at 1 day, 5.8 MPa at 3 days, 7.3 MPa at 7 days, and 6.3 MPa at 28 days. This indicates that the strength of concrete increased at each age after adding commercially available early-strength water-reducing agent.

[0125] When the early-strength water-reducing agent in Examples 1 to 5 of this invention is added, the 1-day compressive strength of the concrete is greater than 12 MPa, the 3-day compressive strength is greater than 32.8 MPa, the 7-day compressive strength is greater than 34.9 MPa, and the 28-day compressive strength is greater than 38.0 MPa. In particular, the 1-day compressive strength of the concrete with the early-strength water-reducing agent in Example 4 reaches 18 MPa, the 3-day compressive strength reaches 36.4 MPa, the 7-day compressive strength is 37.8 MPa, and the 28-day compressive strength is 41.2 MPa. The 1-day and 3-day compressive strength of the concrete increases significantly.

[0126] As can be seen from the above, compared with concrete without water-reducing agent and concrete with commercially available early-strength polycarboxylate water-reducing agent, concrete with early-strength water-reducing agent in Examples 1 to 5 of the present invention has higher early strength and better early-strength effect.

[0127] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the present invention's specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An early-strength water-reducing agent, characterized in that, The raw materials, by weight, include: 25-36 parts polyether macromonomer, 3-7 parts unsaturated acid, 0.05-0.2 parts initiator, 0.08-0.26 parts chain transfer agent, 2-4 parts pH adjuster, 10-18 parts early-strength monomer, and 42-58 parts water; the raw materials for the early-strength monomer, by weight, include 36-48 parts organic aluminum alkoxide, 50-65 parts acid anhydride, and 0.2-0.8 parts catalyst; The acid anhydride includes at least one of acrylic anhydride, butenoic anhydride, butenediic anhydride, pentenoic anhydride, pentenediic anhydride, hexenoic anhydride, cyclohexenoic anhydride, and hexenediic anhydride. The method for preparing the early-strength monomer is as follows: add the organic aluminum alkoxide to the reactor, heat to 95℃~120℃, add the acid anhydride and the catalyst, and continue to keep warm for 6~8h.

2. The early-strength water-reducing agent according to claim 1, characterized in that, The organic aluminum alkoxides include at least one of aluminum ethoxide, aluminum diethylethoxide, aluminum propoxide, aluminum isopropoxide, aluminum isopropoxide dimethyl, aluminum n-butoxide, aluminum isobutoxide, and aluminum pentaerythritol.

3. The early-strength water-reducing agent according to claim 1, characterized in that, The catalyst includes at least one of sulfuric acid and phosphoric acid.

4. The early-strength water-reducing agent according to claim 1, characterized in that, The polyether macromonomer is isopentenyl alcohol polyoxyethylene ether, with a molecular weight of 5000~6000.

5. The early-strength water-reducing agent according to claim 1, characterized in that, The unsaturated acid includes at least one of acrylic acid, maleic acid, and itaconic acid.

6. The early-strength water-reducing agent according to claim 1, characterized in that, The initiator includes at least one of ammonium persulfate, potassium persulfate, sodium persulfate, and hydrogen peroxide; the chain transfer agent includes at least one of fatty alcohol thiols, dodecyl mercaptan, isopropanol, sodium bisulfite, mercaptoethanol, mercaptoacetic acid, mercaptopropanol, and sodium hypophosphite; and the pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

7. A method for preparing an early-strength water-reducing agent as described in claim 1, characterized in that, Includes the following steps: Add 25-36 parts of polyether macromonomer and 30-38 parts of water to the reactor, and heat to 60-70℃; After the polyether macromonomers are dissolved, the first mixture is added, and the second and third mixtures are added dropwise at the same time; after the second and third mixtures are added, the temperature is maintained for 1 to 2 hours; then 2 to 4 parts of pH adjuster are added to obtain the early strength water-reducing agent. The first mixture is a mixture of 3-7 parts of unsaturated acid and 10-18 parts of early-strength monomer; the second mixture is a mixture of 0.05-0.2 parts of initiator and 6-10 parts of water; and the third mixture is a mixture of 0.08-0.26 parts of chain transfer agent and 6-10 parts of water.

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