Concrete slump retaining agent and preparation method thereof

Abstract

The invention relates to a concrete slump retaining agent and a preparation method thereof, and the concrete slump retaining agent is prepared from the following raw materials in parts by weight: 2.13-4.25 parts of unsaturated phosphate functional monomer; 200 to 220 parts of polyether monomer; 10 to 20 parts of unsaturated acid; 20 to 30 parts of acrylic ester; 0.53 to 0.97 part of a chain transfer agent; 0.91 to 2.06 parts of an oxidizing agent; 0.20 to 0.75 part of a reducing agent; and 245 to 265 parts of water. Wherein the unsaturated phosphate functional monomer is prepared from the following raw materials: polyethylene glycol, unsaturated organic phosphoric acid and a catalyst. The unsaturated phosphate functional monomer is introduced into the concrete slump retaining agent, and when the concrete slump retaining agent is applied to concrete, unsaturated phosphate in the unsaturated phosphate functional monomer can form a stable complex with calcium ions on the surfaces of cement particles, so that active sites, capable of being adsorbed by mud particles, on the surfaces of the cement particles can be reduced; the concrete can keep good flowability within a certain time, so that the slump retaining and mud resisting effects are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, in particular to a concrete collapse-preventing agent and a preparation method thereof. Background Art

[0002] With the development of the concrete industry, polycarboxylic acid slump retaining agent has become a mainstream product for concrete production and application due to its unique molecular structure and excellent performance. However, modern engineering has continuously improved the requirements for concrete performance. In order to save costs, most cement plants currently grind cement too finely and add too many admixtures, which results in increased water demand and rapid hydration of concrete, seriously affecting the slump. At the same time, with the increase in high-rise buildings and environmental protection requirements, mixing plants are often located on the edge of cities, and long-term concrete pumping and transportation have put forward higher requirements on the fluidity and slump of concrete.

[0003] The existing problems are mainly due to poor quality of sand and gravel materials, unreasonable mix ratio, low water-cement ratio, poor sand and gravel grading and environmental factors, etc. These factors lead to insufficient workability and collapse resistance of concrete, which has become a key problem that many researchers need to solve urgently. Summary of the invention

[0004] Based on this, it is necessary to provide a concrete collapse-preventing agent with good collapse-preventing performance and a preparation method thereof.

[0005] To achieve the above object, the present invention provides a technical solution:

[0006] A concrete collapse preventing agent, wherein the raw materials for preparing the concrete collapse preventing agent include, by weight:

[0007]

[0008]

[0009] The raw materials for preparing the unsaturated phosphate functional monomer include polyethylene glycol, unsaturated organic phosphoric acid and a catalyst.

[0010] Furthermore, the unsaturated organic phosphoric acid includes at least one of ethylene phosphoric acid, 1-methyl vinyl phosphoric acid, ethylene diphosphoric acid, 1-butene phosphoric acid, propylene phosphoric acid and 2-methyl vinyl phosphoric acid.

[0011] Furthermore, the molecular weight of the polyethylene glycol is 200-600.

[0012] Furthermore, the catalyst includes at least one of methanesulfonic acid, p-toluenesulfonic acid and concentrated sulfuric acid.

[0013] Furthermore, the mass of the catalyst is 0.5% to 2.0% of the sum of the mass of the polyethylene glycol and the unsaturated organic phosphoric acid.

[0014] Furthermore, the preparation steps of the unsaturated phosphate functional monomer are as follows:

[0015] Under the catalytic action of a catalyst, the polyethylene glycol and the unsaturated organic phosphoric acid are reacted for 4 to 6 hours at a temperature of 50 to 90° C. After the reaction, dehydration is performed to obtain the unsaturated phosphate functional monomer.

[0016] Further, the acrylic acid ester includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, butyl acrylate, methyl acrylate, hydroxypropyl acrylate and 2-hydroxy-2-butyl acrylate.

[0017] Furthermore, the oxidant includes at least one of sodium percarbonate, tert-butyl hydroperoxide, sodium peracetate, sodium persulfate and ammonium persulfate.

[0018] Furthermore, the reducing agent includes at least one of ferrous oxide, ferrous sulfate, ferrous nitrate, sodium sulfite, and sodium sulfide.

[0019] Furthermore, the unsaturated acid includes at least one of acrylic acid, sodium acrylate, fumaric acid and methacrylic acid.

[0020] Furthermore, the chain transfer agent includes at least one of mercaptoethanol, thioglycolic acid, n-dodecyl mercaptan, tert-dodecyl mercaptan and sodium formate.

[0021] The present invention also provides a method for preparing a concrete collapse-preventing agent, comprising the steps of:

[0022] The concrete collapse preventing agent is obtained by adopting a one-step synthesis method, in which the polyether monomer, unsaturated acid, acrylate and unsaturated phosphate functional monomer are reacted under the action of a chain transfer agent, an oxidant and a reducing agent.

[0023] Beneficial effects of the present invention:

[0024] The present invention introduces an unsaturated phosphate functional monomer into a concrete slump retaining agent. The unsaturated phosphate functional monomer is prepared by using unsaturated organic phosphoric acid and polyethylene glycol as raw materials. When applied to concrete, the unsaturated phosphate in the unsaturated phosphate functional monomer can form a stable complex with calcium ions on the surface of cement particles. The complexing action can reduce active sites on the surface of cement particles that can be adsorbed by mud particles, reduce the interaction force between mud particles and cement particles, thereby delaying the hydration process of cement, allowing the concrete to maintain good fluidity for a certain period of time, reducing slump loss, and improving the overall performance of the concrete. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] Example 1

[0028] The preparation method of the concrete collapse-preventing agent (by weight) comprises the following steps:

[0029] S100, preparation of unsaturated phosphate functional monomer

[0030] Before the reaction begins, high-purity nitrogen is continuously introduced into the reaction vessel. After the air in the reaction system is fully replaced, 56 parts of polyethylene glycol with a molecular weight of 400, 17.08 parts of p-1-methylvinyl phosphonic acid and 0.51 parts of concentrated sulfuric acid are added into the reaction vessel, and the reaction is carried out at 80° C. for 5 hours. After the reaction is completed, the unsaturated phosphate functional monomer is obtained by dehydration;

[0031] S200, Preparation of Concrete Collapse Retaining Agent

[0032] Add 209 parts of polyether macromonomer (ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000), 1.22 parts of sodium persulfate, 2.25 parts of the unsaturated phosphate functional monomer prepared in step S100 and 160 parts of deionized water into a reaction bottle, and raise the temperature to 30° C. After the polyether monomer is dissolved, add the first mixed solution and the second mixed solution into the reaction container, react for 2 hours, and keep warm for 1 hour to obtain the polycarboxylic acid collapse retaining agent;

[0033] The first mixed liquid is obtained by mixing 10.35 parts of sodium acrylate, 27.20 parts of hydroxyethyl acrylate and 30 parts of deionized water, and the second mixed liquid is obtained by mixing 0.22 parts of ferrous oxide, 0.66 parts of mercaptoethanol and 60 parts of deionized water.

[0034] Example 2

[0035] The preparation method of the concrete collapse-preventing agent (by weight) comprises the following steps:

[0036] S100, preparation of unsaturated phosphate functional monomer

[0037] Before the reaction begins, high-purity nitrogen is continuously introduced into the reaction vessel. After the air in the reaction system is fully replaced, 40 parts of polyethylene glycol with a molecular weight of 500, 10.37 parts of ethylene phosphoric acid and 0.60 parts of concentrated sulfuric acid are added into the reaction vessel, and the reaction is carried out at 85° C. for 5 hours. After the reaction is completed, the unsaturated phosphate functional monomer is obtained by dehydration;

[0038] S200, Preparation of Concrete Collapse Retaining Agent

[0039] Add 212 parts of polyether macromonomer (ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000), 0.98 parts of sodium percarbonate, 3.42 parts of the unsaturated phosphate functional monomer prepared in step S100 and 163 parts of deionized water into a reaction bottle, and raise the temperature to 30° C. After the polyether monomer is dissolved, add the first mixed solution and the second mixed solution into the reaction container, react for 2 hours, and keep warm for 1 hour to obtain the polycarboxylic acid collapse retaining agent;

[0040] The first mixed liquid is obtained by mixing 14.56 parts of acrylic acid, 25.60 parts of hydroxyethyl methacrylate and 30 parts of deionized water, and the second mixed liquid is obtained by mixing 0.27 parts of ferrous oxide, 0.73 parts of n-dodecyl mercaptan and 60 parts of deionized water.

[0041] Example 3

[0042] The preparation method of the concrete collapse-preventing agent (by weight) comprises the following steps:

[0043] S100, preparation of unsaturated phosphate functional monomer

[0044] Before the reaction begins, high-purity nitrogen is continuously introduced into the reaction vessel. After the air in the reaction system is fully replaced, 72 parts of polyethylene glycol with a molecular weight of 600, 27.47 parts of ethylene diphosphoric acid and 1.49 parts of p-toluenesulfonic acid are added into the reaction vessel, and the reaction is carried out at 90° C. for 6 hours. After the reaction is completed, the unsaturated phosphate functional monomer is obtained by dehydration;

[0045] S200, Preparation of Concrete Collapse Retaining Agent

[0046] Add 218 parts of polyether macromonomer (ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000), 1.35 parts of ammonium persulfate, 2.77 parts of the unsaturated phosphate functional monomer prepared in step S100 and 169 parts of deionized water into a reaction bottle, and raise the temperature to 45° C. After the polyether monomer is dissolved, add the first mixed solution and the second mixed solution into the reaction container, react for 2 hours, and keep warm for 1 hour to obtain the polycarboxylic acid collapse retaining agent;

[0047] The first mixed liquid is obtained by mixing 12.40 parts of sodium acrylate, 24.30 parts of hydroxypropyl acrylate and 30 parts of deionized water, and the second mixed liquid is obtained by mixing 0.35 parts of ferrous sulfate, 0.57 parts of sodium formate and 60 parts of deionized water.

[0048] Example 4

[0049] The preparation method of the concrete collapse-preventing agent (by weight) comprises the following steps:

[0050] S100, preparation of unsaturated phosphate functional monomer

[0051] Before the reaction begins, high-purity nitrogen is continuously introduced into the reaction vessel. After the air in the reaction system is fully replaced, 34 parts of polyethylene glycol with a molecular weight of 200, 26.96 parts of propylene phosphoric acid and 1.04 parts of p-methanesulfonic acid are added into the reaction vessel, and the reaction is carried out at 60° C. for 4 hours. After the reaction is completed, the unsaturated phosphate functional monomer is obtained by dehydration;

[0052] S200, Preparation of Concrete Collapse Retaining Agent

[0053] Add 216 parts of polyether macromonomer (ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000), 1.17 parts of sodium peracetate, 3.74 parts of unsaturated phosphate functional monomer prepared in step S100 and 174 parts of deionized water into a reaction bottle, and raise the temperature to 45° C. After the polyether monomer is dissolved, add the first mixed solution and the second mixed solution into the reaction container, react for 2 hours, and keep warm for 1 hour to obtain the polycarboxylic acid collapse retaining agent;

[0054] The first mixed liquid is obtained by mixing 14.30 parts of sodium methacrylate, 28.50 parts of hydroxyethyl acrylate and 30 parts of deionized water, and the second mixed liquid is obtained by mixing 0.42 parts of ferrous nitrate, 0.70 parts of tert-dodecyl mercaptan and 60 parts of deionized water.

[0055] Example 5

[0056] The preparation method of the concrete collapse-preventing agent (by weight) comprises the following steps:

[0057] S100, preparation of unsaturated phosphate functional monomer

[0058] Before the reaction begins, high-purity nitrogen is continuously introduced into the reaction vessel. After the air in the reaction system is fully replaced, 50 parts of polyethylene glycol with a molecular weight of 600, 11.33 parts of 1-butene phosphoric acid and 0.37 parts of p-toluenesulfonic acid are added into the reaction vessel, and the reaction is carried out at 80° C. for 5 hours. After the reaction is completed, the unsaturated phosphate functional monomer is obtained by dehydration;

[0059] S200, Preparation of Concrete Collapse Retaining Agent

[0060] Add 204 parts of polyether macromonomer (ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000), 1.30 parts of tert-butyl hydroperoxide, 4.11 parts of the unsaturated phosphate functional monomer prepared in step S100 and 156 parts of deionized water into a reaction bottle, and raise the temperature to 35° C. After the polyether monomer is dissolved, add the first mixed solution and the second mixed solution into the reaction container, react for 2 hours, and keep warm for 1 hour to obtain the polycarboxylic acid collapse retaining agent;

[0061] The first mixed liquid is obtained by mixing 13.72 parts of fumaric acid, 24.50 parts of butyl acrylate and 30 parts of deionized water, and the second mixed liquid is obtained by mixing 0.30 parts of sodium sulfide, 0.64 parts of thioglycolic acid and 60 parts of deionized water.

[0062] Example 6

[0063] The preparation method of the concrete collapse-preventing agent (by weight) comprises the following steps:

[0064] S100, preparation of unsaturated phosphate functional monomer

[0065] Before the reaction begins, high-purity nitrogen is continuously introduced into the reaction vessel to ensure that the air in the reaction system is fully replaced. 45 parts of polyethylene glycol with a molecular weight of 400, 19.22 parts of 2-methylvinyl phosphoric acid and 0.64 parts of concentrated sulfuric acid are added into the reaction vessel, and the reaction is carried out at 75° C. for 5 hours. After the reaction is completed, the unsaturated phosphate functional monomer is obtained by dehydration;

[0066] S200, Preparation of Concrete Collapse Retaining Agent

[0067] Add 211 parts of polyether macromonomer (ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000), 1.24 parts of sodium peracetate, 2.26 parts of the unsaturated phosphate functional monomer prepared in step S100 and 162 parts of deionized water into a reaction bottle, and raise the temperature to 45° C. After the polyether monomer is dissolved, add the first mixed solution and the second mixed solution into the reaction container, react for 2 hours, and keep warm for 1 hour to obtain the polycarboxylic acid collapse retaining agent;

[0068] The first mixed liquid is obtained by mixing 11.50 parts of methacrylic acid, 26.70 parts of 2-hydroxy-2-butyl acrylate and 30 parts of deionized water, and the second mixed liquid is obtained by mixing 0.52 parts of sodium sulfite, 0.53 parts of tert-dodecyl mercaptan and 60 parts of deionized water.

[0069] Comparative Example 1

[0070] Commercially available polycarboxylic acid slump retaining agent, solid content 50%.

[0071] Comparative Example 2

[0072] The other steps and dosages are the same as those in Example 3, except that:

[0073] Step S100 is not included, and the unsaturated phosphate functional monomer in step S200 is replaced with an equal amount of a collapse-preserving functional monomer (capped amide phosphate, a phosphate functional monomer, having the following structural formula:

[0074] ).

[0075] Comparative Example 3

[0076] The other steps and dosages are the same as those in Example 3, except that:

[0077] Step S100 is not included, and the unsaturated phosphate functional monomer in step S200 is replaced by ethylene diphosphoric acid in equal amounts.

[0078] Performance Testing

[0079] The performance tests were conducted on the concrete collapse retaining agents of Comparative Examples 1 to 3 and Examples 1 to 6.

[0080] S100, Raw materials for preparing unsaturated phosphate functional monomer test

[0081] Cement: Conch Cement P.O42.5;

[0082] Sand: machine-made sand, fineness modulus 2.7;

[0083] Stone: particle size 5mm~10mm, crushing value 12.4%.

[0084] S200, concrete mix ratio for preparing concrete collapse-preventing agent

[0085] The mix ratio of concrete raw materials is shown in Table 1:

[0086] Table 1 Concrete mix ratio (unit: kg / m 3 )

[0087] raw materials cement sand Stone water Collapse inhibitor Mix ratio 350 1040 860 160 5.4

[0088] The concrete slump retaining agents of Comparative Examples 1 to 3 and Examples 1 to 6 were diluted with water to prepare samples with a solid content of 10%. The concrete was compared using the mix ratio in Table 1. The evaluation results of the concrete slump / expansion (mm / mm) are shown in Table 2.

[0089] Table 2 Concrete slump / spread evaluation results

[0090]

[0091] From the data in Table 2, the initial slump and expansion of Comparative Example 1 are comparable to those of Example 2, but the loss of Example 2 after 2 hours is 10 mm and 5 mm smaller than that of Comparative Example 1;

[0092] The concrete advantages shown by Example 3, Example 5 and Example 6 are better, and their initial slump is equivalent, but the initial expansion of Example 3 is 10mm larger than that of Example 5 and Example 6, and the expansion loss of Example 3 after 2h is 40mm, which is 10mm and 5mm smaller than that of Example 5 and Example 6, respectively, and the slump retention is better. From the perspective of the inverting time, the inverting time of Example 3 is the shortest at 3.2s, and the inverting time of Comparative Example 1 is the longest at 5.2s. The reason for this is that the molecular chain of 1-butene phosphate in Example 5 is longer, and the steric hindrance effect that can be provided is better. The methyl group in the 2-methylvinyl phosphoric acid in Example 6 can increase the steric hindrance, making the adsorption of the complex on the surface of cement particles more stable, further delaying cement hydration, and improving the slump-preserving performance, while the two phosphate groups of the ethylene diphosphoric acid in Example 3 can provide more complexing sites, more effectively adsorbed on the surface of cement particles, reducing the active sites on the surface of cement particles for mud particles to adsorb, reducing the interaction between mud particles and cement particles, thereby delaying the hydration process of cement, allowing the concrete to maintain good fluidity for a certain period of time, and playing a good role in slump-preserving. Therefore, the comprehensive performance of Example 3 is stronger, and the slump-preserving performance is the best.

[0093] In addition, the initial concrete states of Example 4 and Comparative Example 1 are similar, but the loss of Example 4 after 2 hours is smaller than that of Comparative Example 1, indicating that the collapse retention of Example 4 is still better than that of Comparative Example 1.

[0094] Compared with the data of Example 3, the initial slump and expansion of Comparative Example 2 are equivalent to those of Example 3, but after 2h, the slump of Example 3 is 15mm larger than that of Comparative Example 2, and the expansion is also 15mm larger than that of Comparative Example 2. The slump loss of Example 3 after 2h is 10mm smaller than that of Comparative Example 2, and the expansion loss after 2h is 15mm smaller than that of Comparative Example 2. The inverting time of Example 3 is 1.2 seconds shorter than that of Comparative Example 2. It can be seen that the performance of Comparative Example 2, which introduces a collapse-retaining monomer-capped amide phosphate, in terms of collapse-retaining performance and workability is worse than that of Example 3.

[0095] Compared with the data of Example 3, the initial expansion of Comparative Example 3 is 30 mm larger than that of Example 3. After 2 hours, the slump of Example 3 is 30 mm larger than that of Comparative Example 3, and the expansion is also 65 mm larger than that of Comparative Example 3. The slump loss of Example 3 after 2 hours is 20 mm smaller than that of Comparative Example 3, and the expansion loss of Example 3 after 2 hours is 35 mm smaller than that of Comparative Example 3. The inverting time of Example 3 is 1.5 seconds shorter than that of Comparative Example 3. This shows that the performance of Comparative Example 3, which directly introduces unesterified unsaturated organic phosphoric acid, is worse than that of Example 3 in terms of slump retention performance and workability.

[0096] The concrete data of Examples 1 to 6 show that the concrete collapse retaining agent prepared from the unsaturated phosphate functional monomer generated from polyethylene glycol and unsaturated organic phosphoric acid has better collapse retaining property than the commercially available collapse retaining agent and exhibits better workability.

[0097] 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 concrete collapse-preventing agent, characterized in that: The raw materials for preparing the concrete collapse-preventing agent include, by weight: The raw materials for preparing the unsaturated phosphate functional monomer include polyethylene glycol, unsaturated organic phosphoric acid and a catalyst.

2. The concrete collapse preventing agent according to claim 1, characterized in that: The unsaturated organic phosphoric acid includes at least one of ethylene phosphoric acid, 1-methyl vinyl phosphoric acid, ethylene diphosphoric acid, 1-butene phosphoric acid, propylene phosphoric acid and 2-methyl vinyl phosphoric acid.

3. The concrete collapse preventing agent according to claim 1, characterized in that: The molecular weight of the polyethylene glycol is 200-600.

4. The concrete collapse preventing agent according to claim 1, characterized in that: The catalyst includes at least one of methanesulfonic acid, p-toluenesulfonic acid and concentrated sulfuric acid.

5. The concrete collapse preventing agent according to claim 1, characterized in that: The mass of the catalyst is 0.5% to 2.0% of the sum of the mass of the polyethylene glycol and the unsaturated organic phosphoric acid.

6. The concrete collapse preventing agent according to claim 1, characterized in that: The preparation steps of the unsaturated phosphate functional monomer are as follows: Under the catalytic action of a catalyst, the polyethylene glycol and the unsaturated organic phosphoric acid are reacted for 4 to 6 hours at a temperature of 50 to 90° C. After the reaction, dehydration is performed to obtain the unsaturated phosphate functional monomer.

7. The concrete collapse preventing agent according to claim 1, characterized in that: The acrylic acid ester includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, butyl acrylate, methyl acrylate, hydroxypropyl acrylate and 2-hydroxy-2-butyl acrylate.

8. The concrete collapse preventing agent according to claim 1, characterized in that: The oxidant includes at least one of sodium percarbonate, tert-butyl hydroperoxide, sodium peracetate, sodium persulfate and ammonium persulfate.

9. The concrete collapse preventing agent according to claim 1, characterized in that: The reducing agent includes at least one of ferrous oxide, ferrous sulfate, ferrous nitrate, sodium sulfite and sodium sulfide.

10. A method for preparing the concrete collapse-preventing agent according to any one of claims 1 to 9, characterized in that: Includes steps: The concrete collapse preventing agent is obtained by adopting a one-step synthesis method, in which the polyether monomer, unsaturated acid, acrylate and unsaturated phosphate functional monomer are reacted under the action of a chain transfer agent, an oxidant and a reducing agent.

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