Foam-stabilizing functional monomer, long-acting foam-stabilizing slump-retaining material for small-slump concrete and preparation method of long-acting foam-stabilizing slump-retaining material

Abstract

The invention relates to the technical field of building admixtures, in particular to a foam-stabilizing functional monomer, a long-acting foam-stabilizing slump retaining material for small-slump concrete and a preparation method of the long-acting foam-stabilizing slump retaining material. A foam-stabilizing functional monomer prepared from pentaerythritol allyl ether, alkylene oxide and an epoxy sulfonic acid compound through an addition polymerization reaction is used for synthesizing the long-acting foam-stabilizing slump retaining material for the small-slump concrete, and the prepared long-acting foam-stabilizing slump retaining material for the small-slump concrete not only has excellent slump retaining performance, but also has a good air entraining effect; the concrete slump retaining agent is more stable in foaming when being applied to concrete, can prevent bubbles from cracking or overflowing in the concrete stirring, transporting, loading, unloading and pouring processes, is particularly suitable for small-slump concrete projects with long-acting slump retaining requirements, and has important practical application value.

Description

Technical Field

[0001] The invention relates to the technical field of building admixtures, in particular to a foam-stabilizing functional monomer and a long-acting foam-stabilizing collapse-preserving material for small-slump concrete and a preparation method thereof. Background Art

[0002] With the rapid development of the national economy, the types of projects have become more diversified. The requirements for concrete in the construction of some special projects are also somewhat different from those in ordinary projects. In the production of prefabricated buildings and the construction of special projects (such as nuclear power), there is a demand for small slump concrete.

[0003] The concept of low-slump concrete refers to concrete with a slump of 120 to 170 mm at the time of machine making, good workability, moderate viscosity, small slump loss over time, and no slump increase in the later period due to delayed reaction. When using conventional slump-retaining agents to prepare low-slump concrete, reducing the dosage can control the initial slump, but the later loss is large and the slump-retaining requirements cannot be met. The loss of fluidity of the concrete will also cause the concrete to be unable to be pumped for construction. If the amount of water-reducing agent is reduced and the amount of slump-retaining agent is increased to control the initial slump, the concrete may be able to meet the needs of long-term slump-retaining, but the concrete is prone to swelling and bleeding during transportation. In addition, the air content of concrete tends to gradually decrease over time during transportation, resulting in a large loss of air content in the concrete during application compared to the initial machine.

[0004] In order to maintain the long-term stability of small slump concrete, the key control technology is not only to maintain fluidity but also to maintain air content. Long-distance transportation or vibration will cause bubbles and ruptures in the concrete, resulting in a large loss of air content, and the workability and flowability of the concrete will deteriorate, resulting in accelerated loss, packaging difference, water seepage, etc. Summary of the invention

[0005] In order to solve the problem mentioned in the above background that the air content of concrete is lost greatly and the workability and flowability of concrete are deteriorated, the present invention provides a foam stabilizing functional monomer, the structural formula of which is: ; Wherein, R1 and R2 are polyether chains obtained by polymerization of ethylene oxide and propylene oxide, respectively, and R3 is -CH2- or -C2H4-.

[0006] On the basis of the above embodiments, further, the weight average molecular weight is 400-1000.

[0007] The present invention provides a method for preparing any of the above-mentioned foam stabilizing functional monomers, comprising the following steps: S100, adding an initiator and a catalyst into a reaction kettle, and evacuating the reactor; S200, replace with N2 1 to 5 times, raise the reaction temperature to 100 to 180°C, introduce alkylene oxide into the reactor, the reaction pressure is 0.2 to 5 MPa, and react for 1 to 3 hours; S300, when the pressure of the reactor stops decreasing, evacuate the reactor, preferably to -0.1 MPa, and then introduce the epoxy sulfonic acid compound into the reactor, maintaining the temperature at 100-180°C; S400, when the pressure in the reactor stops decreasing, the reaction is finished, and the foam stabilizing functional monomer is obtained.

[0008] On the basis of the above embodiment, further, the initiator is tetrapentanol allyl ether; The catalyst is one or more of sodium methoxide, sodium tert-butoxide, sodium ethoxide, lithium aluminum hydroxide, sodium hydroxide, potassium hydroxide, sodium cyanide, and metallic sodium, and the amount of the catalyst is 0.1% to 0.3% of the mass of ethylene oxide and / or propylene oxide; The alkylene oxide is ethylene oxide and / or propylene oxide, and the number of the alkylene oxides is 2 to 12.

[0009] On the basis of the above embodiment, further, the epoxysulfonic acid compound is any one of oxirane-2-yl methane sulfonate and 2,3-epoxypropyl methane sulfonate.

[0010] On the basis of the above embodiment, further, the epoxysulfonic acid compound is any one of oxirane-2-yl methane sulfonate and 2,3-epoxypropyl methane sulfonate.

[0011] The present invention also provides a method for preparing a long-acting foam-stabilizing collapse-preventing material for small-slump concrete, which is prepared by using any of the foam-stabilizing functional monomers described above, and the preparation steps are as follows: Step a, mixing the foam stabilizing functional monomer, unsaturated carboxylic acid or unsaturated carboxylic anhydride, unsaturated carboxylic acid ester small monomer, and polyether macromonomer in a mass ratio of (1-6): (2-15): (16-40): 200, and adding water to dissolve them to obtain a copolymer monomer mixture solution; Step b, dripping the above-mentioned comonomer mixture solution, initiator aqueous solution and molecular weight regulator aqueous solution into a reaction kettle filled with water, stirring and reacting, the reaction temperature is 5-80°C, the dropping time is 1.0-2.0h, and the reaction is continued for 0.5-2.0h after the dropwise addition is completed to obtain a copolymer product, and then adjusting the pH to 5-7 with alkali to obtain a long-acting stable foam type collapse-preserving material for small slump concrete.

[0012] On the basis of the above embodiment, further, the unsaturated carboxylic acid or unsaturated carboxylic anhydride is at least one of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, acrylic anhydride and itaconic anhydride; The unsaturated carboxylic acid ester is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl glycidyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,3-propylene glycol diacrylate, 1,5-pentanediol dimethacrylate, and glycerol 1,3-dimethacrylate; The polyether macromonomer M is at least one of 3-methyl-3-butene-1-polyethylene glycol, 2-methylallyl polyethylene glycol, ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 1000-6000.

[0013] On the basis of the above embodiment, further, the total amount of water makes the mass concentration of the copolymer product be 20% to 80%, the amount of the initiator is 0.5% to 3.0% of the total mass of the solute in the copolymer mixture solution, and the amount of the molecular weight regulator is 0.2% to 2.0% of the total mass of the solute in the copolymer mixture solution; The initiator is a water-soluble inorganic peroxide initiator, a water-soluble redox initiator system or a water-soluble azo initiator, that is, the water-soluble inorganic peroxide initiator is at least one of ammonium persulfate and potassium persulfate.

[0014] On the basis of the above embodiments, further, the water-soluble redox initiation system is at least one of hydrogen peroxide-bleaching powder, hydrogen peroxide-ascorbic acid, and persulfate-sodium bisulfite; wherein hydrogen peroxide-bleaching powder refers to a mixture of hydrogen peroxide and bleaching powder, and the specific mixing ratio can be adjusted accordingly by those skilled in the art according to the use of the initiator. The same applies to the two water-soluble redox initiation systems of hydrogen peroxide-ascorbic acid and persulfate-sodium bisulfite.

[0015] The water-soluble azo initiator is at least one of azobisisobutylamidine hydrochloride, azobisisopropylimidazoline hydrochloride, azobiscyanovaleric acid, and azobisisopropylimidazoline; The molecular weight regulator is at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, isopropanol, sodium hypophosphite, trisodium phosphate, sodium formate, sodium acetate and dodecanethiol.

[0016] The technical solution of the present invention has the following principles and beneficial effects: 1. The foam-stabilizing functional monomer provided by the present invention can be used for the synthesis of polycarboxylic acid collapse-preventing materials. The prepared collapse-preventing materials not only have excellent collapse-preventing performance, but also have good air entraining effect, and the foaming when applied to concrete is more stable.

[0017] 2. The long-acting foam-stabilizing collapse-preserving material for small-slump concrete provided by the present invention introduces foam-stabilizing functional monomers into the polycarboxylic acid structure to form a micro-cross-linked network structure, which is interspersed with the side chains of ether macromonomers. This structure allows the molecules to be arranged more tightly and orderly at the gas-liquid interface, which on the one hand enhances the electrostatic repulsion in the molecular structure, and on the other hand can form a hydration layer on the concrete surface to produce a synergistic effect, and can also control the hydrolysis rate of the ester group in the molecular chain to prevent the concrete from bleeding and swelling due to excessive hydrolysis.

[0018] In addition, the prepared foam-stabilizing functional monomer improves the surface activity of the material, giving it excellent air-entraining properties and greatly improving its bubble stabilizing effect, which can prevent bubbles from bursting or overflowing during concrete mixing, transportation, loading and unloading, and pouring. It is particularly suitable for small-slump concrete projects with long-term collapse protection requirements, and has important practical application value. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] 1. The present invention provides the following structural examples of foam stabilizing functional monomers: ; Wherein, R1 and R2 are polyether chains obtained by polymerization of ethylene oxide and propylene oxide, respectively, and R3 is -CH2- or -C2H4-, and its weight average molecular weight is 400-1000.

[0021] 2. The present invention also provides the following embodiment of a long-acting foam-stabilizing collapse-preventing material for small-slump concrete: The preparation example of the foam stabilizing functional monomer A is shown in the following table: Table 1

[0022] The preparation method of the above embodiment is to add the initiator tetrapentyl alcohol allyl ether and the catalyst to the reactor, evacuate to -0.1 MPa, replace with N2 3 times, heat the reaction to 100-180°C (specifically, temperature 1 in the table), introduce alkylene oxide (wherein EO is ethylene oxide and PO is propylene oxide) into the reactor, and the reaction pressure is 0.2-5 MPa; react for 1-3 hours until the pressure of the reactor no longer decreases, evacuate to -0.1 MPa, and then introduce oxirane-2-ylmethane sulfonate (i.e., epoxysulfonic acid compound) into the reactor, maintain the temperature at 100-180°C (specifically, temperature 2 in the table), and when the pressure of the reactor no longer decreases, the reaction is terminated, and the foam stabilizing functional monomer A of each embodiment is obtained.

[0023] Preparation Example of Comonomer Mixture Solution B: The foam stabilizing functional monomer A, unsaturated carboxylic acid or unsaturated carboxylic anhydride, unsaturated carboxylic acid ester small monomer, and polyether macromonomer M prepared above are mixed in a mass ratio of (1-6): (2-15): (16-40): 200, and water is added to dissolve them to obtain a copolymer monomer mixture solution B. The specific implementation example is shown in Table 2: Table 2

[0024] The above-mentioned comonomer mixture solution B, initiator aqueous solution and molecular weight regulator aqueous solution are dripped into a reaction kettle filled with water, and the stirrer is turned on to react. The reaction temperature is 5-80°C and the dripping time is 1.0-2.0h. After the dripping is completed, the reaction is continued for 0.5-2.0h to obtain a copolymer product, and then the pH is adjusted to 5-7 with alkali to obtain a long-acting stable foam type collapse-preserving material C for small slump concrete. The specific implementation example is shown in Table 3: Table 3

[0025] The present invention provides the following comparative examples of collapse-preventing materials: Comparative Example 1: The commercially available model is BSF concrete collapse prevention material Y1.

[0026] Comparative Example 2 Using the process of Example 1 as the basic process, without adding A1 to the synthesis and keeping other reaction conditions unchanged, Y2 was obtained.

[0027] Comparative Example 3 Y3 was prepared by using the process of Example 1 as the basic process, without adding A1 into the synthesis, using the commercially available foam stabilizing functional unit WP-01 instead of A1, and keeping other reaction conditions unchanged.

[0028] Comparative Example 4 The process of Example 1 is used as the basic process, without adding A1 for synthesis. After the copolymerization reaction is completed, the commercially available foam stabilizing and air entraining agent Q1 is compounded and added in an equal amount to A1, and other reaction conditions remain unchanged to prepare Y4.

[0029] The above embodiments and comparative examples were subjected to the following performance tests: The collapse retaining agent materials prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were compounded with the Kezhijie water-reducing agent PointTS7 at a solid-to-solid ratio of 5:5 to form a sample with a solid content of 10%. When the dosage of Examples 1 to 6 was 1.0% (relative to the amount of cementitious material), the water reduction rate was higher than 35%, the 1d compressive strength ratio was higher than 200%, the 7d compressive strength ratio was higher than 190%, the 28d compressive strength ratio was higher than 180%, and the 28d shrinkage ratio was less than 50%.

[0030] Minfu P.O42.5 ordinary Portland cement is used, and the concrete mix ratio is: cement 325kg / m 3 、Fly ash 50kg / m 3 、Mineral powder 50kg / m 3 、Machinery sand 770kg / m 3 、Stone 1022kg / m 3 、Water 170kg / m 3 According to the above admixture formula, the performance of the slump retaining agents prepared in Examples 1 to 6 and Comparative Examples 1 to 4 was compared, and the dosage of the admixture was adjusted to make the initial slump of the concrete (150±20) mm. The test indicators included the slump of the concrete over time at 0h, 1h, 2h, 3h and 4h, air content, water bleeding rate and compressive strength at each age. The test results are shown in Table 4: Table 4

[0031] From the test results in the above table, we can get: 1) The slump-preserving material prepared by the present invention can be applied to small slump concrete to achieve long-term slump preservation of 4 hours, the slump is stable during the process, does not return to a large value, does not lag in water bleeding, the air content is very stable, and has a good foam stabilizing effect.

[0032] 2) Comparing Y1 and C1, the commercially available collapse-preserving material showed an obvious slump increase within 2 hours, and the air content out of the machine was relatively high. The air content gradually decreased with time, resulting in air loss, unstable bubbles, and low concrete strength at 1 day.

[0033] 3) By comparing Y2 with C1, the preparation of the collapse-preserving material does not introduce the homemade foam-stabilizing functional monomer A1, the dosage of the admixture is higher than that of the collapse-preserving material C1 prepared by the present invention, and the slump returns to a large value within 2 hours, and the loss begins to appear after 2 hours, and the collapse-preserving is poor. Secondly, the air content is unstable, the air content out of the machine is high, the air loss is fast, and the air content is low after 2 hours. In addition, the collapse-preserving is fast, the concrete does not collapse, and the strength difference is not large.

[0034] 4) By comparing Y3 with C1, A1 was replaced with a commercially available foam-stabilizing monomer. It can be seen that the dosage of the admixture is twice that of the patent of the present invention. Concrete re-swelled after 1 hour and began to lose strength between 1 hour and 2 hours. The collapse resistance performance was not as good as the embodiment provided by the present invention. In terms of air content, the air content out of the machine was relatively high. As time went on, the air content gradually decreased, the foam-stabilizing performance was poor, and the strength at 1 day was low.

[0035] 5) Comparing Y4 with C1, replacing A1 with a commercially available air-entraining agent compound, the admixture dosage becomes higher, and the slump shows a trend of increasing and then decreasing, and a phenomenon of returning to large size occurs. The loss is large in 3 hours and cannot be maintained for 4 hours. The air content is unstable and the air loss is large. The strength at each age is lower than that of the patented product of the present invention, which has a great impact on the strength.

[0036] From the above comparison, it can be concluded that the long-term foam-stabilizing collapse-preserving material for small-slump concrete prepared by using the improved foam-stabilizing functional monomer of the present invention not only has excellent collapse-preserving performance, but also has a good air-entraining effect. The foaming applied to the concrete is more stable, and the bubbles can be prevented from bursting or overflowing during the mixing, transportation, loading and unloading and pouring of the concrete. It is particularly suitable for small-slump concrete projects with long-term collapse-preserving requirements, and has important practical application value.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A foam stabilizing functional monomer, characterized in that: The structural formula is: ； Wherein, R1 and R2 are polyether chains obtained by polymerization of ethylene oxide and propylene oxide, respectively, and R3 is -CH2- or -C2H4-.

2. The foam stabilizing functional monomer according to claim 1, characterized in that: The weight average molecular weight of the foam stabilizing functional monomer is 400-1000.

3. A method for preparing the foam stabilizing functional monomer according to claim 1 or 2, characterized in that: The following steps are involved: S100, adding an initiator and a catalyst into a reaction kettle, and evacuating the reactor; S200, replace with N2 1 to 5 times, raise the reaction temperature to 100 to 180°C, introduce alkylene oxide into the reactor, the reaction pressure is 0.2 to 5 MPa, and react for 1 to 3 hours; S300, when the pressure of the reactor stops decreasing, evacuate the reactor, and then introduce the epoxy sulfonic acid compound into the reactor, maintaining the temperature at 100-180°C; S400, when the pressure in the reactor stops decreasing, the reaction is finished, and the foam stabilizing functional monomer is obtained.

4. The method for preparing the foam stabilizing functional monomer according to claim 3, characterized in that: The initiator is tetrapentanol allyl ether; The catalyst is one or more of sodium methoxide, sodium tert-butoxide, sodium ethoxide, lithium aluminum hydroxide, sodium hydroxide, potassium hydroxide, sodium cyanide, and metallic sodium, and the amount of the catalyst is 0.1% to 0.3% of the mass of ethylene oxide and / or propylene oxide; The alkylene oxide is ethylene oxide and / or propylene oxide, and the number of alkylene oxides is 2 to 12; The epoxysulfonic acid compound is any one of oxirane-2-yl methane sulfonate and 2,3-epoxypropyl methane sulfonate.

5. A method for preparing a long-lasting foam-stabilizing collapse-preventing material for small-slump concrete, characterized in that: The foam stabilizing functional monomer is prepared by the foam stabilizing functional monomer described in claim 1 or 2 or the foam stabilizing functional monomer described in claim 3 or 4, and the preparation steps are as follows: Step a, mixing the foam stabilizing functional monomer, unsaturated carboxylic acid or unsaturated carboxylic anhydride, unsaturated carboxylic acid ester small monomer, and polyether macromonomer in a mass ratio of (1-6): (2-15): (16-40): 200, and adding water to dissolve them to obtain a copolymer monomer mixture solution; Step b, dripping the above-mentioned comonomer mixture solution, initiator aqueous solution and molecular weight regulator aqueous solution into a reaction kettle filled with water, stirring and reacting, the reaction temperature is 5-80°C, the dropping time is 1.0-2.0h, and the reaction is continued for 0.5-2.0h after the dropwise addition is completed to obtain a copolymer product, and then adjusting the pH to 5-7 with alkali to obtain a long-acting stable foam type collapse-preserving material for small slump concrete.

6. The method for preparing the long-acting stable foam type collapse-preventing material for small slump concrete according to claim 5, characterized in that: The unsaturated carboxylic acid or unsaturated carboxylic anhydride is at least one of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, acrylic anhydride and itaconic anhydride; The unsaturated carboxylic acid ester is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl glycidyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,3-propylene glycol diacrylate, 1,5-pentanediol dimethacrylate, and glycerol 1,3-dimethacrylate.

7. The method for preparing the long-acting stable foam type collapse-preventing material for small slump concrete according to claim 5, characterized in that: The polyether macromonomer M is at least one of 3-methyl-3-butene-1-polyethylene glycol, 2-methylallyl polyethylene glycol, ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 1000-6000.

8. The method for preparing the long-acting stable foam type collapse-preventing material for small slump concrete according to claim 5, characterized in that: The total amount of water makes the mass concentration of the copolymer product 20% to 80%, the amount of initiator used is 0.5% to 3.0% of the total mass of the solute in the copolymer monomer mixture solution, and the amount of molecular weight regulator used is 0.2% to 2.0% of the total mass of the solute in the copolymer monomer mixture solution.

9. The method for preparing the long-acting stable foam type collapse-preventing material for small slump concrete according to claim 5, characterized in that: The initiator is a water-soluble inorganic peroxide initiator, a water-soluble redox initiator system or a water-soluble azo initiator, that is, the water-soluble inorganic peroxide initiator is at least one of ammonium persulfate and potassium persulfate.

10. The method for preparing the long-acting stable foam type collapse-preventing material for small slump concrete according to claim 9, characterized in that: The water-soluble redox initiation system is at least one of hydrogen peroxide-bleaching powder, hydrogen peroxide-ascorbic acid, and persulfate-sodium bisulfite; The water-soluble azo initiator is at least one of azobisisobutylamidine hydrochloride, azobisisopropylimidazoline hydrochloride, azobiscyanovaleric acid, and azobisisopropylimidazoline; The molecular weight regulator is at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, isopropanol, sodium hypophosphite, trisodium phosphate, sodium formate, sodium acetate and dodecanethiol.

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