Concrete improver, preparation method and concrete material comprising concrete improver

Abstract

The invention relates to a concrete improver, a preparation method and a concrete material comprising the concrete improver. The concrete improver comprises a copolymer, the copolymer is obtained by copolymerization of an esterified monomer A and one or more olefinic unsaturated acids or acid anhydrides B, the esterified monomer A is obtained by esterification of a first compound shown in a formula I and a second compound shown in a formula II, R1-O-(R2-O) n-R2-OH is shown in a formula IR3-P (= O) (OH) 2, R1 is C1-C6 alkyl, R2 is C1-C4 alkylene, n is the degree of polymerization, and n is the degree of polymerization. N is an integer from 2 to 300, and R3 is a C2-C6 alkenyl group. The esterified monomer A formed by the first compound and the second compound has'end-capped polyether chain segment-phosphonate bond-phosphonic acid group-alkenyl double bond ', so that the esterified monomer A can be copolymerized with one or more olefinic unsaturated acids or anhydrides B to form a multifunctional copolymer. The concrete improver provided by the invention can improve the flowability, cohesiveness and water-retaining property of concrete, so that the concrete is good in workability, full in slurry and low in bleeding rate, and the compressive strength of the concrete is improved.

Description

Technical Field

[0001] This disclosure relates to the field of building material admixtures, and more specifically, to a concrete improver, a preparation method thereof, and concrete materials comprising the same. Background Technology

[0002] Concrete workability is a crucial indicator of concrete construction performance, directly impacting the quality of pouring and construction efficiency. Currently, concrete workability improvers on the market mainly include naphthalene-based, polycarboxylate-based, and acrylamide-based improvers. While acrylamide-based improvers offer some water retention and thickening effects, they suffer from significant drawbacks such as poor environmental friendliness, temperature sensitivity, poor compatibility with cement, and insufficient concrete strength. Existing technologies utilize terpolymers or compound additives to improve workability retention time or inhibit bleeding, but these methods still face limitations such as unstable raw material supply, high costs, and the inability to fundamentally address environmental and concrete strength issues.

[0003] Therefore, there is an urgent need to develop a new type of workability improver that is environmentally friendly, has good temperature adaptability, excellent compatibility with cement, and can improve the comprehensive properties of concrete, such as workability. Summary of the Invention

[0004] The purpose of this invention is to provide a concrete improver and its preparation method, so as to solve the problem that existing concrete workability modifiers cannot simultaneously achieve the fluidity, cohesiveness and water retention of concrete, while reducing the bleeding rate of concrete and improving the compressive strength of concrete.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, the present invention provides a concrete improver comprising a copolymer, wherein the copolymer is obtained by copolymerization of esterified monomer A with one or more olefinic unsaturated acids or anhydrides B, wherein the esterified monomer A is obtained by esterification of a first compound of formula I with a second compound of formula II. R 1 -O-(R 2 -O) n -R 2 -OH formula I R 3 -P(=O)(OH)2 Formula II Among them, R 1 It is a C1-C6 alkyl group, R 2 It is a C1-C4 alkylene group, where n is the degree of polymerization and is an integer from 2 to 300, R 3 It is a C2-C6 alkenyl group.

[0006] In one embodiment, the first compound is methoxy polyethylene glycol, the second compound is vinylphosphonic acid, and the esterifying monomer A is methoxy polyethylene glycol-vinylphosphonate as shown in Formula III. CH3O-(CH2CH2O) n -CH2CH2O-P(O)(OH)-CH=CH2 (Formula III) Wherein, n is an integer from 110 to 230; and / or the olefinic unsaturated acid or anhydride B is one or more of methacrylic acid, acrylic acid, maleic anhydride, itaconic acid, and fumaric acid.

[0007] In one embodiment, when the olefinic unsaturated acid or anhydride B comprises two olefinic unsaturated acids or anhydrides, the mixing mass ratio is in the range of 1:9 to 9:1; preferably, the olefinic unsaturated acid or anhydride B comprises methacrylic acid and acrylic acid in a mass ratio of (0.3~3):1, preferably 1:1, or comprises maleic anhydride and itaconic acid in a mass ratio of (1~5):1, preferably 2:1.

[0008] In one embodiment, the concrete improver further includes a composite functional additive compounded with the copolymer, the composite functional additive including one or more of a tackifier and a filler, preferably including both a tackifier and a filler, the mass ratio of the tackifier and the filler being (2~8):1, preferably 4:1.

[0009] In one embodiment, the thickener is a cellulose compound, preferably hydroxypropyl methylcellulose ether, wherein the viscosity of the hydroxypropyl methylcellulose ether at room temperature is 10,000~80,000 mPa. s, preferably 40000mPa s; The filler is selected from one or more of nano-silica, nano-titanium dioxide, nano-alumina or nano-calcium carbonate, preferably nano-calcium carbonate, and the average particle size of nano-calcium carbonate is 50~100nm. The mass ratio of hydroxypropyl methylcellulose ether to nano-calcium carbonate is (2~8):1.

[0010] On the other hand, the present invention provides a method for preparing a concrete improver, comprising the following steps: Step 1, Esterification reaction: The first compound shown in Formula I and the second compound shown in Formula II are subjected to an esterification reaction to obtain esterified monomer A; Step 2, copolymerization reaction: The esterified monomer A obtained in step 1, one or more olefinic unsaturated acids or anhydrides B, an initiator and a chain transfer agent are copolymerized in a solvent to obtain a copolymer mother liquor; R 1 -O-(R 2 -O)n -R 2 -OH formula I R 3 -P(=O)(OH)2 Formula II Among them, R 1 It is a C1-C6 alkyl group, R 2 It is a C1-C4 alkylene group, where n is the degree of polymerization and is an integer from 2 to 300, R 3 It is a C2-C6 alkenyl group, wherein the solvent is preferably an aqueous solvent.

[0011] In one embodiment, the method for preparing the concrete improver further includes: Step 3, compounding: Add a composite functional additive to the copolymer mother liquor. The composite functional additive includes one or more of a tackifier and a filler, preferably including both a tackifier and a filler. The mass ratio of the tackifier to the filler is (2~8):1, preferably 4:1. The thickener is a cellulose compound, preferably hydroxypropyl methylcellulose ether, which has a viscosity of 10,000~80,000 mPa at room temperature. s, preferably 40000 mPa s; The filler is selected from one or more of nano-silica, nano-titanium dioxide, nano-alumina or nano-calcium carbonate, preferably nano-calcium carbonate, and the average particle size of nano-calcium carbonate is 50~100nm. The mass ratio of hydroxypropyl methylcellulose ether to nano-calcium carbonate is (2~8):1.

[0012] In one embodiment, in step 1: the molar ratio of the first compound to the second compound is 1:(1.2~1.5), the esterification reaction is carried out at 110~130°C for 4~6 hours under concentrated sulfuric acid catalysis to obtain esterified monomer A, and the esterification rate of the first compound is greater than or equal to 92%.

[0013] In one embodiment, in step 2: the amount of esterifying monomer A is 40-60 parts by mass, the amount of olefinic unsaturated acid or anhydride B is 20-30 parts, the amount of initiator is 3-7 parts, the amount of chain transfer agent is 2-5 parts, and the copolymerization reaction is carried out at 90-100°C for 4-6 hours; and / or In step 3: the compound is stirred at 55~65℃ and 800~1000r / min for 1.2~2.2 hours.

[0014] In one embodiment, the initiator is selected from one or more of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride; and / or The chain transfer agent is selected from one or more of mercaptopropionic acid, mercaptoacetic acid, and sodium hypophosphite.

[0015] In another aspect, the present invention provides a concrete material comprising the above-mentioned concrete improver.

[0016] In one embodiment, the concrete material further includes cement, aggregate, and water-reducing agent, wherein the ratio of the concrete improver to the water-reducing agent by weight is in the range of 0.1% to 0.5%, preferably 0.2%, and the water-reducing agent is preferably a polycarboxylate-based water-reducing agent.

[0017] Compared with the prior art, the present invention has significant advantages: The concrete improver provided by this invention can improve the fluidity, cohesiveness and water retention of concrete, resulting in good workability, full paste and low bleeding rate, and can also improve the compressive strength of concrete. Attached Figure Description

[0018] Figure 1 This is the infrared spectrum of the copolymer obtained in Example 2. Detailed Implementation

[0019] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0020] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0021] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0022] I. Concrete Improvers The present invention provides a concrete improver comprising a copolymer obtained by copolymerization of an esterified monomer (terminated polyether segment-phosphonate bond-phosphonic acid group-alkenyl double bond) and one or more olefinic unsaturated acids or anhydrides (functional monomers), preferably further comprising a composite functional additive compounded with the copolymer.

[0023] Esterified monomer (terminated polyether segment - phosphonate bond - phosphonic acid group - alkenyl double bond) The esterified monomer is obtained by esterification of the first compound and the second compound.

[0024] The first compound can be represented by formula I: R 1 -O-(R2 -O) n -R 2 -OH formula I In equation I, R 1 It can be a C1-C6 alkyl group, for example, R 1 It can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, and cyclohexyl, etc. Preferably, R¹ is methyl.

[0025] R 2 It can be a C1-C4 alkylene group, for example, R 2 It can be methylene, ethylene, 1,2-propylene, 1,3-propylene, and 1,4-butylene, etc. Preferably, R 2 It is ethylene.

[0026] n is the degree of aggregation, which can be an integer from 2 to 300, for example, an integer from 10 to 280, an integer from 50 to 260, or an integer from 100 to 250. Preferably, n is an integer from 110 to 230.

[0027] The second compound can be represented by formula II: R 3 -P(=O)(OH)2 Formula II In Equation II, R 3 It can be C2-C6 alkenyl, preferably, R 3 It can be vinyl, allyl, 1-propenyl, butenyl, etc. Preferably, R 3 It is a C2-C4 alkenyl group, for example, vinyl or allyl. More preferably, R³ is vinyl.

[0028] In one embodiment, the first compound of Formula I and the second compound of Formula II can be esterified to obtain an esterified monomer as shown in Formula IV, having a structure of "terminated polyether segment-phosphonate bond-phosphonic acid group-alkenyl double bond". R 1 -O-(R 2 -O) n -R 2 -OP(=O)(OH)-R 3 Formula IV Among them, R 1 R 2 R 3 And n can be the same as defined above.

[0029] The esterified monomers described above may have phosphonate bonds (-OP(=O)-) formed through the above esterification reaction, which connect the hydroxyl group (-OH) of the end-capped polyether segment to the phosphonic acid group (-P(=O)-OH) of the alkenyl phosphonic acid, forming a linear molecular structure of "end-capped polyether segment-phosphonate bond-phosphonic acid group-alkenyl double bond".

[0030] In the above-mentioned esterified monomers, the alkenyl double bond (reactive site) is an alkenyl double bond (-CH=CH2) located at the end of the molecule, which has high free radical reactivity and can undergo copolymerization reaction with functional monomers such as methacrylic acid, acrylic acid, maleic anhydride, itaconic acid, and fumaric acid to form a copolymer backbone with a specific molecular weight distribution.

[0031] The phosphonic acid groups in the aforementioned esterified monomers can serve as interfacial adsorption sites, and the phosphonic acid groups in the copolymer chains can dissociate to release H+. + This forms negatively charged phosphonate ions, which react with Ca²⁺ ions on the surface of cement particles. + Al³ + When metal ions form stable coordination bonds, they can effectively disperse cement particles and reduce agglomeration.

[0032] The aforementioned esterified monomer thus possesses a hydrophilic-lipophilic balanced structure, retaining both the hydrophilic polyether units of the end-capped polyether segments, such as polyoxyethylene units (-CH2CH2O-), which can form a hydration film on the surface of cement particles, preventing collision and aggregation of cement particles; and phosphonic acid groups, whose cement-loving properties ensure that the molecules can be tightly adsorbed onto the surface of cement particles, forming a synergistic effect of "adsorption-dispersion-water retention".

[0033] In one specific embodiment, the first compound may be methoxy polyethylene glycol, the second compound may be vinylphosphonic acid, and the esterifying monomer A may be methoxy polyethylene glycol-vinylphosphonate as shown in Formula III: CH3O-(CH2CH2O) n -CH2CH2O-P(O)(OH)-CH=CH2 (Formula III) Wherein, n is the degree of aggregation, which can be an integer from 2 to 300, for example, an integer from 10 to 280, an integer from 50 to 260, or an integer from 100 to 250. Preferably, n is an integer from 110 to 230.

[0034] Alkenes are unsaturated acids or anhydrides (functional monomers). The type and amount of functional monomers (olefinic unsaturated acids or anhydrides) can be adjusted according to specific needs to meet different application environments. The olefinic unsaturated acid or anhydride can be one or more of methacrylic acid, acrylic acid, maleic anhydride, itaconic acid, and fumaric acid. For example, the olefinic unsaturated acid or anhydride is methacrylic acid.

[0035] When there are two or more olefinic unsaturated acids or anhydrides, for example, they can be a mixture of methacrylic acid and acrylic acid, a mixture of maleic anhydride and itaconic acid, or a mixture of maleic anhydride and fumaric acid, etc.

[0036] When the olefinic unsaturated acid or anhydride is a mixture of two functional monomers, the mass ratio of the two functional monomers can be from 1:9 to 9:1. For example, the mass ratio of the two functional monomers can be 2:8, 7:3, 4:6, or 1:1.

[0037] In one embodiment, the olefinic unsaturated acid or anhydride may be a mixture of methacrylic acid and acrylic acid. Furthermore, the mass ratio of methacrylic acid to acrylic acid may be (0.3~3):1, preferably 1:1.

[0038] In another embodiment, the olefinic unsaturated acid or anhydride can be a mixture of maleic anhydride and itaconic acid. Furthermore, the mass ratio of maleic anhydride to itaconic acid can be (1~5):1, preferably 2:1.

[0039] Due to differences in molecular structure, different functional monomers can be copolymerized with the above-mentioned esterified monomers to suit the following different application scenarios: Methacrylic acid: Contains methyl groups (-CH3), which can enhance the steric hindrance of copolymer molecular chains and improve the fluidity stability of concrete in high-temperature environments (30~40℃).

[0040] Itaconic acid / fumaric acid: Contains two carboxyl groups (-COOH), which can increase the adsorption sites of the copolymer and cement particles after copolymerization, making it suitable for the low water-cement ratio requirements of C50 and above high-performance concrete.

[0041] Maleic anhydride readily copolymerizes with the double bonds of esterified monomers, exhibiting high reaction efficiency and making it suitable for industrial mass production.

[0042] Mixed use (e.g., methacrylic acid + acrylic acid = 1:1): can balance high-temperature stability and room-temperature fluidity, making it suitable for concrete construction in areas with large seasonal temperature differences.

[0043] The number average molecular weight of the above copolymers can be 60 to 14,000, for example, 400 to 13,000, 2,000 to 12,000, 4,000 to 11,000, preferably 5,000 to 10,000.

[0044] Composite functional additives Composite functional additives include one or more of tackifiers and fillers, preferably including both tackifiers and fillers.

[0045] The thickener is a cellulose compound. In one embodiment, the thickener is hydroxypropyl methylcellulose ether.

[0046] The viscosity of hydroxypropyl methylcellulose ether can range from 10,000 to 80,000 mPa at room temperature. s, for example, 20000~60000mPa In one embodiment, the viscosity of hydroxypropyl methylcellulose ether can be 40,000 mPa at room temperature. s.

[0047] The filler is selected from one or more of nano-silica, nano-titanium dioxide, nano-alumina, or nano-calcium carbonate. Nano-calcium carbonate is preferred, and the average particle size of nano-calcium carbonate is 50-100 nm, for example, 60-90 nm or 70-80 nm.

[0048] Hydroxypropyl methylcellulose ether is mixed with the nano-calcium carbonate at a mass ratio ranging from 2:1 to 8:1, preferably at a mass ratio of 4:1.

[0049] In summary, the concrete improver of this invention utilizes a high-molecular-weight copolymer obtained by copolymerizing esterified monomers and functional monomers. Composite functional additives can also be added as needed, achieving synergistic optimization of concrete workability and a significant improvement in overall performance. The phosphonate and phosphonic acid groups introduced into the copolymer enhance the multi-point adsorption capacity of the molecular chains and cement particles, forming a more stable dispersion system. Furthermore, the phosphonic acid groups introduced by alkenyl phosphonate esterification in the copolymer significantly improve its adaptability to different cement types (such as silicate cement, ordinary silicate cement, slag silicate cement, and fly ash silicate cement) and aggregate gradations, thereby improving the workability of concrete and effectively overcoming the limitation of traditional improvers being "one-material-one-use".

[0050] Meanwhile, the thickeners in the composite functional additives can enhance cohesion, and the fillers can effectively fill the pores, thereby reducing the bleeding rate of concrete materials and achieving an upgrade of the three-dimensional optimization effect of "flow-cohesion-water retention".

[0051] The concrete improver of this invention balances environmental friendliness and mechanical performance. The raw materials are free of formaldehyde and naphthalene-based components, and do not corrode steel reinforcement. The use of higher molecular weight esterified monomers can form a more stable interfacial transition zone during cement hydration, improving the compressive strength of concrete.

[0052] Finally, the concrete improver of the present invention is easy to apply and does not require changes to the existing concrete mixing process. Only the amount added and the mixing time need to be slightly adjusted according to the concrete strength grade, which perfectly adapts to the needs of industrial production and on-site construction.

[0053] II. Preparation Method of Concrete Improver The preparation method of concrete improver may include step 1 (esterification reaction) and step 2 (copolymerization reaction), and optionally step 3 (compounding).

[0054] Step 1, esterification reaction: The esterification reaction step may include esterifying a first compound represented by Formula I with a second compound represented by Formula II to obtain an esterified monomer.

[0055] R 1 -O-(R 2 -O) n -R 2 -OH formula I R 3 -P(=O)(OH)2 Formula II Among them, R 1 It is a C1-C6 alkyl group, R 2 It is a C1-C4 alkylene group, where n is the degree of polymerization and is an integer from 2 to 300, R 3 It is C2-C6 alkenyl. The first and second compounds can be the same as those described in the esterification monomer. For example, the first compound is preferably methoxy polyethylene glycol, and the second compound is preferably vinylphosphonic acid.

[0056] The molar ratio of the first compound to the second compound can be 1:(1.2~1.5), for example, 1:1.2, 1:1.4 or 1:1.35.

[0057] According to one specific embodiment, the first compound and the second compound are subjected to an esterification reaction at 110~130°C for 4~6 hours under a catalyst to obtain an esterified monomer.

[0058] The catalyst can be selected from p-toluenesulfonic acid, concentrated sulfuric acid, benzenesulfonic acid, methanesulfonic acid and titanates, with concentrated sulfuric acid being preferred.

[0059] The esterification reaction temperature can be controlled at 110~130℃, for example, 120℃ or 125℃.

[0060] The esterification reaction time can be controlled to be 4 to 6 hours, for example, 4.5 hours, 5 hours or 5.5 hours.

[0061] Furthermore, in step 1, the esterification rate of the first compound must be strictly monitored to be ≥92%, for example, 94% or 95%. The esterification rate of the first compound = (moles of hydroxyl groups in the first compound that formed ester bonds) ÷ (total moles of hydroxyl groups in the initial first compound). Insufficient esterification rate of the first compound will lead to insufficient content of esterified monomers in subsequent copolymerization reactions with functional monomers, resulting in decreased dispersion performance of the finished product. The esterification rate can be monitored in real-time using acid-base titration to ensure that the esterification rate of the first compound meets the standard.

[0062] The esterified monomer synthesized in step 1 has hydrophilic polyether segments, strongly adsorbing phosphonic acid groups, and polymerizable double bonds.

[0063] Step 2, copolymerization reaction: The copolymerization step may include copolymerizing the esterified monomer obtained in step 1 with one or more olefinic unsaturated acids or anhydrides, an initiator and a chain transfer agent in a solvent to obtain a copolymer mother liquor.

[0064] Various olefinic unsaturated acids or anhydrides can be the same as those described in the functional monomers above, and can be one or more of methacrylic acid, acrylic acid, maleic anhydride, itaconic acid, and fumaric acid.

[0065] The initiator described above may be selected from one or more of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride. For example, ammonium persulfate or azobisisobutyramidine hydrochloride.

[0066] The chain transfer agent described above may be selected from one or more of mercaptopropionic acid, mercaptoacetic acid, and sodium hypophosphite. For example, mercaptoacetic acid or mercaptopropionic acid.

[0067] The solvents mentioned above are preferably tetrahydrofuran, 1,4-dioxane, acetone, and water, with water being the most preferred.

[0068] In step 2, the amount of each raw material can be as follows, by mass: 40-60 parts of esterifying monomer (preferably 45-55 parts, for example 50 parts), 20-30 parts of olefinic unsaturated acid or anhydride (preferably 23-28 parts, for example 25 parts), 3-7 parts of initiator (preferably 4-6 parts, for example 5 parts), and 2-5 parts of chain transfer agent (preferably 3-4 parts); for example, 40 parts of esterifying monomer, 20 parts of olefinic unsaturated acid or anhydride, 3 parts of initiator, and 2 parts of chain transfer agent.

[0069] According to a specific embodiment, the esterified monomer obtained in step 1 is copolymerized with one or more olefinic unsaturated acids or anhydrides, an initiator and a chain transfer agent in a solvent at 90-100°C for 4-6 hours to obtain a copolymer mother liquor.

[0070] The reaction temperature of the copolymerization reaction can be controlled between 90 and 110°C, for example, 93°C, 95°C, 98°C, 100°C or 105°C.

[0071] The reaction time for copolymerization can be controlled between 4 and 6 hours, for example, 4.2 hours, 4.5 hours, 5 hours, 5.5 hours, or 5.8 hours.

[0072] According to one specific embodiment, the initiator can be added to the reaction system dropwise, and the dropping rate can be controlled. For example, when using maleic anhydride, because maleic anhydride has high reactivity, the dropping rate of the initiator can be reduced to 1 drop / second.

[0073] According to one specific embodiment, when using itaconic acid, because itaconic acid has a high carboxyl content, the reaction temperature can be appropriately increased to 100~105℃ to ensure complete copolymerization.

[0074] Step 2 copolymerizes the large esterified monomer from Step 1 with the small functional monomer. By adjusting the type and ratio of functional monomers, the adsorption characteristics and spatial conformation of the copolymer can be precisely controlled, thereby adapting it to different cement systems and construction environments.

[0075] Step 3, compounding: The compounding step may include adding composite functional additives to the copolymer mother liquor obtained in step 2.

[0076] The composite functional additive can be the same as the above-mentioned composite functional additive, and can be one or more of the thickener and filler, and preferably hydroxypropyl methylcellulose ether and nano calcium carbonate.

[0077] The thickener is a cellulose compound, preferably hydroxypropyl methylcellulose ether, with a viscosity of 10,000~80,000 mPa at room temperature. s, with a preferred viscosity of 40000 mPa at room temperature. s.

[0078] The filler is selected from one or more of nano-silica, nano-titanium dioxide, nano-alumina or nano-calcium carbonate, preferably nano-calcium carbonate, and the average particle size of nano-calcium carbonate is 50~100nm.

[0079] Hydroxypropyl methylcellulose ether and nano-calcium carbonate are mixed in a mass ratio ranging from 2:1 to 8:1, preferably in a mass ratio of 4:1.

[0080] According to a specific embodiment, a composite functional additive is added to the copolymer mother liquor obtained in step 2, and the mixture is stirred for 1.2 to 2.2 hours at 55 to 65°C and 800 to 1000 r / min to perform compounding.

[0081] The above compounding temperature can be controlled at 55~65℃, for example, 55℃, 60℃ or 65℃.

[0082] The re-stirring time can be 1.2 to 2.2 hours, for example, 1.2 hours, 1.7 hours or 2.2 hours.

[0083] The stirring speed can be 800~1000 r / min, for example, 800 r / min, 900 r / min or 1000 r / min.

[0084] Step 3 introduces composite functional additives, such as tackifiers and fillers, into the copolymer to achieve simultaneous optimization of flowability, water retention and strength.

[0085] According to the above method of the present invention, an esterified monomer with a multifunctional composite structure of "terminated polyether segment-phosphonate bond-phosphonic acid group-alkenyl double bond" is obtained by esterification reaction, and then the esterified monomer is copolymerized with an alkene unsaturated acid or anhydride to form a copolymer.

[0086] Furthermore, the copolymers can be compounded to ultimately achieve a concrete modifier that combines fluidity, cohesiveness, and water retention. Moreover, the preparation process of this method is simple, does not require complex operations, and has controllable costs.

[0087] According to another aspect of the present invention, a concrete material is provided, comprising the above-described concrete improver. The concrete material may also include cement, aggregates, and water-reducing agents, etc.

[0088] According to one specific embodiment, the concrete improver is added to the concrete material in the form of an aqueous admixture solution. For example, the concrete improver can be used in conjunction with a water-reducing agent, and the ratio of the concrete improver to the water-reducing agent by weight can be in the range of 0.1% to 0.5%. In one embodiment, the water-reducing agent can be a polycarboxylate-based water-reducing agent. In another embodiment, the ratio of the concrete improver to the water-reducing agent by weight can be 0.2%.

[0089] The concrete improver and its preparation method according to the embodiments will be described in more detail below with reference to the following examples.

[0090] Example 1 Preparation of MPEG-5000-vinylphosphonate: 100g of MPEG-5000 (number average molecular weight 5000±200, industrial grade) and 22.4g of vinylphosphonic acid (purity 98%) were mixed at a molar ratio of MPEG to vinylphosphonic acid of 1:1.2. The mixture was added to a 500mL four-necked flask, and 0.5g of concentrated sulfuric acid (mass fraction 98%) was added. The mixture was heated to 115℃ and stirred at 300r / min for 4.5 hours. After the reaction was completed, unreacted vinylphosphonic acid and water were removed under reduced pressure at -0.08MPa and 85℃ (removal time 1 hour). The esterification rate was determined to be 95% by acid-base titration, yielding a pale yellow transparent MPEG-5000-vinylphosphonate.

[0091] Synthesis of workability improvers: Raw material composition (parts by weight): MPEG-5000-vinylphosphonate 40 parts, acrylic acid (purity 99.5%) 20 parts, ammonium persulfate (purity 98%) 3 parts, mercaptoacetic acid (purity 98%) 2 parts, composite functional additives (hydroxypropyl methylcellulose ether 7.2 parts + nano calcium carbonate 1.8 parts), deionized water 120 parts.

[0092] Add MPEG-5000-vinylphosphonate and 60 parts of deionized water to a four-necked flask, heat to 80°C and stir until completely dissolved. Add ammonium persulfate and stir for 10-20 minutes. Add a mixed aqueous solution of acrylic acid and thioglycolic acid at a rate of 1 drop / second. After the addition is complete, heat to 90°C and keep the reaction at this temperature for 4 hours to obtain the copolymer mother liquor. The final solid content is stable at 20%.

[0093] Add 30 parts of deionized water to the copolymer mother liquor, cool to 55°C, add composite functional additives, adjust the speed to 800 r / min and stir for 1.2 hours, cool to room temperature to obtain the improved agent product with a solid content of 15%.

[0094] Example 2 Preparation of MPEG-6000-vinylphosphonate 100g of MPEG-6000 (number average molecular weight 6000±200) and 24.6g of vinylphosphonic acid (purity 98%) (molar ratio 1:1.3) were mixed, 0.6g of concentrated sulfuric acid was added, and the mixture was stirred at 120℃ for 5 hours. Impurities were removed under reduced pressure at -0.085MPa and 90℃. The esterification rate was determined to be 95% by acid-base titration, yielding MPEG-6000-vinylphosphonate.

[0095] Synthesis of workability improvers Raw material composition (parts by weight): MPEG-6000-vinylphosphonate 45 parts, methacrylic acid (12 parts, purity 99%) + acrylic acid (12 parts, purity 99.5%), ammonium persulfate 4 parts, mercaptoacetic acid 3 parts, composite additive (hydroxypropyl methylcellulose ether 8.4 + nano calcium carbonate 2.1) parts, deionized water 135 parts.

[0096] MPEG-6000-vinylphosphonate was added to a flask with 67.5 parts of deionized water, heated to 80°C, and stirred until completely dissolved. Ammonium persulfate was added and stirred for 10-20 minutes. A mixed aqueous solution of methacrylic acid, acrylic acid, and thioglycolic acid was added dropwise at 1.2 drops / second. The mixture was kept at 95°C for 4.2 hours to obtain the copolymer mother liquor, with a final solid content stabilizing at 20%. The copolymer mother liquor was analyzed by Fourier Transform Infrared Spectroscopy (FTIR), and the resulting infrared spectrum is shown below. Figure 1 As shown.

[0097] Add 34 parts of deionized water to the copolymer mother liquor, cool to 55°C, add composite functional additives, adjust the speed to 800 r / min and stir for 1.2 hours, cool to room temperature to obtain the improved agent product with a solid content of 15%.

[0098] Example 3 Preparation of MPEG-7000-vinylphosphonate 100g of MPEG-7000 (number average molecular weight 7000±200) and 25.8g of vinylphosphonic acid (purity 98%) (molar ratio 1:1.35) were mixed, 0.7g of concentrated sulfuric acid was added, and the mixture was stirred at 125℃ for 5 hours. Impurities were removed under reduced pressure at -0.085MPa and 90℃. The esterification rate was determined to be 94% by acid-base titration, yielding MPEG-7000-vinylphosphonate.

[0099] Synthesis of workability improvers Raw material composition (parts by weight): MPEG-7000-vinylphosphonate 48 parts, maleic anhydride (16.7 parts, purity 99%) + itaconic acid (8.3 parts, purity 99%), azobisisobutyramidine hydrochloride 4.5 parts, sodium hypophosphite 3.2 parts, composite additives (hydroxypropyl methylcellulose ether 8.8 + nano calcium carbonate 2.2) parts, deionized water 142 parts.

[0100] Add MPEG-7000-vinylphosphonate and 71 parts of deionized water to a flask, heat to 80°C and stir until completely dissolved. Add azobisisobutyramidine hydrochloride and stir for 10-20 minutes. Add a mixed aqueous solution of sodium hypophosphite dropwise at 1.5 drops / second. Add itaconic acid and maleic anhydride in 6 portions. Keep warm at 95°C for 4.5 hours to obtain copolymer mother liquor. The final solid content is stable at 20%.

[0101] Add 36 parts of deionized water to the copolymer mother liquor, cool to 55°C, add composite functional additives, adjust the speed to 800 r / min and stir for 1.2 hours, cool to room temperature to obtain the improved agent product with a solid content of 15%.

[0102] Example 4 Preparation of MPEG-8000-vinylphosphonate 100g of MPEG-8000 (number average molecular weight 8000±200) and 27g of vinylphosphonic acid (purity 98%) (molar ratio 1:1.4) were mixed, 0.8g of concentrated sulfuric acid was added, and the mixture was stirred at 125℃ for 5.5 hours. Impurities were removed under reduced pressure at -0.085MPa and 95℃. The esterification rate was determined to be 94% by acid-base titration, yielding MPEG-8000-vinylphosphonate.

[0103] Synthesis of workability improvers Raw material composition (parts by weight): 50 parts MPEG-8000-vinylphosphonate, 26 parts fumaric acid (99% purity), 5 parts ammonium persulfate, 3.5 parts mercaptoacetic acid, 9.6 parts composite additive (hydroxypropyl methylcellulose ether + 2.4 parts nano calcium carbonate), and 150 parts deionized water.

[0104] Add MPEG-7000-vinylphosphonate and 75 parts of deionized water to a flask, heat to 80°C and stir until completely dissolved. Add ammonium persulfate and stir for 10-20 minutes. Add a mixed aqueous solution of thioglycolic acid at 1.5 drops / second. Add fumaric acid in 6 portions. Keep warm at 95°C for 5 hours to obtain copolymer mother liquor. The final solid content is stable at 20%.

[0105] Add 38 parts of deionized water to the copolymer mother liquor, cool to 55°C, add composite functional additives, adjust the speed to 800 r / min and stir for 1.2 hours, cool to room temperature to obtain the improved agent product with a solid content of 15%.

[0106] Example 5 Preparation of MPEG-10000-vinylphosphonate 100g of MPEG-10000 (number average molecular weight 10000±200) and 30.5g of vinylphosphonic acid (purity 98%) (molar ratio 1:1.5) were mixed, 1g of concentrated sulfuric acid was added, and the mixture was stirred at 130℃ for 6 hours. Impurities were removed under reduced pressure at 100℃ with a vacuum degree of -0.085MPa. The esterification rate was determined to be 94% by acid-base titration, thus obtaining MPEG-10000-vinylphosphonate.

[0107] Synthesis of workability improvers Raw material composition (parts by weight): 50 parts MPEG-10000-vinylphosphonate, 28 parts itaconic acid (purity 99%), 5 parts potassium persulfate, 4 parts mercaptopropionic acid, 10.4 parts composite additive (hydroxypropyl methylcellulose ether + 2.6 parts nano calcium carbonate), and 170 parts deionized water.

[0108] Comparative Example 1 Commercially available GJ-03 Comparative Example 2 Commercially available AZ-40 Performance Testing and Results Analysis To verify that the concrete improvers prepared in Examples 1-5 of the present invention have the above-mentioned advantages, the spread, bleeding ratio and compressive strength of concrete materials using the concrete improvers of Examples 1-7 and Comparative Examples 1-2 were tested.

[0109] The testing standards refer to GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" and GB / T8076. The bleeding rate (%) was determined using the method specified in 2008 "Concrete Admixtures", and the compressive strength of concrete samples after 28 days of curing was tested. The test results are shown below.

[0110] Table 1. Raw material usage and basic mix proportions for concrete (kg / m²) 3 )

[0111] Among them, the cement is P·O42.5 Qianshan cement; the fly ash is Grade I; the sand is standard sand with a fineness modulus of 2.5 to 3.0; the crushed stone particle size is 10 to 25 mm. At the same time, a workability improver with a solid content of 0.2% is added to the polycarboxylate superplasticizer with a solid content of 10%. The dosage of polycarboxylate superplasticizer is 1‰ (converted to solids) of the cementitious materials (the general term for cement and active mineral admixtures).

[0112] The polycarboxylate superplasticizer used in Examples 1-5 and Comparative Examples 1-2 was commercially available JJ-07. Comparative Examples 1 and 2 used commercially available acrylamide workability modifiers GJ-03 and AZ-40, respectively. A blank sample was also prepared for comparison, containing only the polycarboxylate superplasticizer and no workability modifier.

[0113] Table 2 Comparison of Concrete Application Performance Tests

[0114] The test results show that the workability improver synthesized by MPEG and vinyl phosphonate esterification exhibits good performance when used in combination with polycarboxylate superplasticizer (commercially available JJ-07) with 10% solid content. Compared with the blank sample, the 2-hour spread retention performance of the experimental concretes with the workability improver is significantly improved. Examples 1-5 are significantly better than commercially available GJ-03 and AZ-40 in terms of spread retention performance.

[0115] Regarding workability: The concrete in Examples 1-5 has good workability, full slurry, and some even have the characteristic of fast flow; while the commercially available GJ-03 and AZ-40 concrete has average workability and poor encapsulation.

[0116] Regarding the bleeding rate: The bleeding rates of Examples 1-5 were significantly lower than those of the commercially available GJ-03 and AZ-40 in Comparative Examples 1-2, indicating that the bleeding of concrete was improved under the action of a solid content of 0.2% and a workability improver.

[0117] Regarding compressive strength: The compressive strength of Examples 1-5 at 3d, 7d, and 28d were all higher than those of the commercially available GJ-03 and AZ-40 in Comparative Examples 1-2, indicating that the polycarboxylate superplasticizer (commercially available JT-07) combined with the workability improver can effectively improve the compressive strength development of concrete, with a 7-11% increase in 28d compressive strength, showing significant advantages compared to commercially available products.

[0118] In summary, the concrete workability improver synthesized by MPEG and vinylphosphonate esterification can effectively optimize the workability and bleeding rate of concrete, improve the compressive strength of concrete, and make the overall performance of concrete superior to commercially available acrylamide workability improvers.

[0119] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0120] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0121] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A concrete improver, characterized in that, The copolymer is obtained by copolymerization of esterified monomer A with one or more olefinic unsaturated acids or anhydrides B. The esterified monomer A is obtained by esterification of the first compound shown in Formula I and the second compound shown in Formula II. R 1 -O-(R 2 -O) n -R 2 -OH of formula I R 3 -P(=O)(OH)2 Formula II Among them, R 1 It is a C1-C6 alkyl group, R 2 It is a C1-C4 alkylene group, where n is the degree of polymerization and is an integer from 2 to 300, R 3 It is a C2-C6 alkenyl group.

2. The concrete improver according to claim 1, wherein, The first compound is methoxy polyethylene glycol, the second compound is vinylphosphonic acid, and the esterified monomer A is methoxy polyethylene glycol-vinylphosphonate as shown in Formula III: CH3O-(CH2CH2O) n -CH2CH2O-P(O)(OH)-CH=CH2 Formula III Where n is an integer from 110 to 230; and / or The olefinic unsaturated acid or anhydride B is one or more of methacrylic acid, acrylic acid, maleic anhydride, itaconic acid, and fumaric acid.

3. The concrete improver according to claim 2, wherein, When the olefinic unsaturated acid or anhydride B comprises two olefinic unsaturated acids or anhydrides, the mixing mass ratio is in the range of 1:9 to 9:

1. Preferably, the olefinic unsaturated acid or anhydride B comprises methacrylic acid and acrylic acid in a mass ratio of (0.3~3):1, preferably 1:1, or comprises maleic anhydride and itaconic acid in a mass ratio of (1~5):1, preferably 2:

1.

4. The concrete improver according to claim 1, wherein, It also includes a composite functional additive compounded with the copolymer, the composite functional additive including one or more of a tackifier and a filler, preferably including both a tackifier and a filler, the mass ratio of the tackifier and the filler being (2~8):1, preferably 4:

1.

5. The concrete improver according to claim 4, wherein, The thickener is a cellulose compound, preferably hydroxypropyl methylcellulose ether, and the viscosity of the hydroxypropyl methylcellulose ether at room temperature is 10,000~80,000 mPa. s, preferably 40000mPa s; The filler is selected from one or more of nano-silica, nano-titanium dioxide, nano-alumina or nano-calcium carbonate, preferably nano-calcium carbonate, and the average particle size of nano-calcium carbonate is 50~100nm. The mass ratio of hydroxypropyl methylcellulose ether to nano-calcium carbonate is (2~8):

1.

6. A method for preparing a concrete improver, characterized in that, Includes the following steps: Step 1, Esterification reaction: The first compound shown in Formula I and the second compound shown in Formula II are subjected to an esterification reaction to obtain esterified monomer A; Step 2, copolymerization reaction: The esterified monomer A obtained in step 1, one or more olefinic unsaturated acids or anhydrides B, an initiator and a chain transfer agent are copolymerized in a solvent to obtain a copolymer mother liquor; R 1 -O-(R 2 -O) n -R 2 -OH of formula I R 3 -P(=O)(OH)2 Formula II Among them, R 1 It is a C1-C6 alkyl group, R 2 It is a C1-C4 alkylene group, where n is the degree of polymerization and is an integer from 2 to 300, R 3 It is a C2-C6 alkenyl group; The solvent is preferably an aqueous solvent.

7. The preparation method according to claim 6, wherein, Also includes: Step 3, compounding: Add a composite functional additive to the copolymer mother liquor. The composite functional additive includes one or more of a tackifier and a filler, preferably including both a tackifier and a filler. The mass ratio of the tackifier to the filler is (2~8):1, preferably 4:

1. The thickener is a cellulose compound, preferably hydroxypropyl methylcellulose ether, which has a viscosity of 10,000~80,000 mPa at room temperature. s, preferably 40000 mPa s; The filler is selected from one or more of nano-silica, nano-titanium dioxide, nano-alumina or nano-calcium carbonate, preferably nano-calcium carbonate, and the average particle size of nano-calcium carbonate is 50~100nm. The mass ratio of hydroxypropyl methylcellulose ether to nano-calcium carbonate is (2~8):

1.

8. The preparation method according to claim 6, wherein, In step 1: the molar ratio of the first compound to the second compound is 1:(1.2~1.5), the esterification reaction is carried out at 110~130℃ for 4~6 hours under concentrated sulfuric acid catalysis to obtain esterified monomer A, and the esterification rate of the first compound is greater than or equal to 92%.

9. The preparation method according to claim 6, wherein, In step 2: by mass, the amount of esterifying monomer A is 40-60 parts, the amount of olefinic unsaturated acid or anhydride B is 20-30 parts, the amount of initiator is 3-7 parts, and the amount of chain transfer agent is 2-5 parts, and the copolymerization reaction is carried out at 90-100°C for 4-6 hours; and / or In step 3: the compound is stirred at 55~65℃ and 800~1000r / min for 1.2~2.2 hours.

10. The preparation method according to claim 9, wherein, The initiator is selected from one or more of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride; and / or The chain transfer agent is selected from one or more of mercaptopropionic acid, mercaptoacetic acid, and sodium hypophosphite.

11. A concrete material, characterized in that, The concrete improver includes any one of claims 1 to 6.

12. The concrete material according to claim 11, wherein, The concrete materials also include cement, aggregates, and water-reducing agents; The concrete improver to the water-reducing agent has a weight ratio of 0.1% to 0.5%, preferably 0.2%. The water-reducing agent is preferably a polycarboxylate-based water-reducing agent.

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