Titanium-doped silica-modified polycarboxylate water reducer and preparation method and application thereof

Abstract

The present invention relates to the technical field of water reducers, and in particular, to a titanium-doped silica-modified polycarboxylate water reducer and a preparation method and application thereof. The preparation method of the titanium-doped silica-modified polycarboxylate water reducer comprises: mixing and reacting a titanium source solution, a silica sol and a silane coupling agent to obtain a titanium-silicon solution; mixing and reacting a titanium-silicon solution, a polyether monomer, an unsaturated carboxylic acid small monomer, an initiator, a reducing agent and water to obtain a titanium-doped silica-modified polycarboxylate water reducer. The present invention uses a titanium-silicon solution to modify a polycarboxylate water reducer to obtain a titanium-doped silica-modified polycarboxylate water reducer, which can make concrete have higher water reduction and collapse retention performance, enhance the early strength of concrete, and reduce cement particle agglomeration.

Description

Technical Field

[0001] The present invention relates to the technical field of water reducing agents, and in particular to a titanium-doped silica-modified polycarboxylic acid water reducing agent, a preparation method thereof and an application thereof. Background Art

[0002] With the rapid development of industry and the complexity of the building application environment, ultra-high performance concrete (UHPC), as an innovative building material with high strength, high density and high durability, has become a hot spot and cutting-edge technology in the field of civil engineering materials in recent years. In recent years, nanotechnology has been used to micro-regulate the structure of cement-based materials. The active hydrophilic groups of polycarboxylate superplasticizer (PCE) are adsorbed on the surface of cement particles, and the hydrophobic side chains extend in the solution and form a physical or chemical adsorption layer on the surface, thereby inhibiting the flocculation of cement particles. This mechanism of action can significantly improve the dispersibility and fluidity of concrete, reduce its viscosity, and improve construction performance. However, due to the rich variety of concrete materials, large differences in elemental composition, and uneven quality, PCE is very sensitive, which seriously affects the water reduction and slump retention performance of concrete. Traditional PCE has a strong delaying effect on cement hydration in concrete systems, resulting in slow early strength growth of concrete and insufficient slump retention performance in the later stage.

[0003] Nano-SiO 2 The surface is rich in hydroxyl groups (-OH), which can form hydrogen bonds with water molecules, making the surface hydrophilic. In cement-based materials, nucleation effect and filling effect will occur, thereby promoting cement hydration reaction, improving the bonding tightness between paste and aggregate, and improving concrete strength. 2 It has a high surface area and is prone to agglomeration. Direct introduction into cement-based materials will also form competitive adsorption with the water reducer, greatly reducing the working performance of the cement-based materials.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a method for preparing a titanium-doped silica-modified polycarboxylate water-reducing agent, wherein the polycarboxylate water-reducing agent is modified by a titanium-silicon solution to obtain a titanium-doped silica-modified polycarboxylate water-reducing agent, which can make concrete have higher water-reducing and slump-retaining properties, enhance the early strength of concrete, and reduce cement particle agglomeration.

[0006] The second object of the present invention is to provide a titanium-doped silica-modified polycarboxylic acid water-reducing agent, which can enhance the early strength of concrete, has better water reduction rate and slump retention performance, can improve the density, durability and overall mechanical properties of concrete, and can also reduce cement particle agglomeration.

[0007] The third object of the present invention is to provide a method for preparing a titanium-doped silica-modified polycarboxylate water-reducing agent and use the titanium-doped silica-modified polycarboxylate water-reducing agent in concrete products.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] The present invention first provides a preparation method of a titanium-doped silica-modified polycarboxylic acid water-reducing agent, comprising the following steps: mixing and reacting a titanium source solution, a silica sol and a silane coupling agent to obtain a titanium-silicon solution; and mixing and reacting the titanium-silicon solution, a polyether monomer, an unsaturated carboxylic acid small monomer, an initiator, a reducing agent and water to obtain the titanium-doped silica-modified polycarboxylic acid water-reducing agent.

[0010] Furthermore, the molar ratio of the titanium element in the titanium source solution to the silicon element in the silica sol is 1:1-10.

[0011] Furthermore, the mass ratio of the silane coupling agent to the silica sol is 0.5 to 1:100.

[0012] Furthermore, the titanium source in the titanium source solution includes at least one of n-butyl titanate, tetraethyl titanate, titanium tetrachloride and titanium trichloride.

[0013] Furthermore, the solvent in the titanium source solution includes at least one of methanol, ethanol and isopropanol.

[0014] Furthermore, the silane coupling agent includes at least one of aminosilane, epoxysilane and thiosilane.

[0015] Furthermore, the method for mixing and reacting the titanium source solution, silica sol and silane coupling agent includes: mixing and stirring the titanium source solution and the silica sol, freezing them to a smoothie state, then stirring and thawing, and repeating the freezing-thawing process at least three times, then adding the silane coupling agent thereto, and stirring at 60-100°C for 4-12 hours.

[0016] Furthermore, the mass ratio of the titanium-silicon solution, the polyether monomer, the unsaturated carboxylic acid small monomer, the reducing agent and the initiator is 4-10: 250-350: 30-50: 0.3-1: 1-4.

[0017] Furthermore, the polyether monomer includes vinyl glycol polyoxyethylene ether.

[0018] Furthermore, the unsaturated carboxylic acid small monomer includes at least one of acrylic acid and methacrylic acid.

[0019] Furthermore, the initiator includes at least one of hydrogen peroxide, sodium persulfate, ammonium persulfate and potassium persulfate.

[0020] Furthermore, the reducing agent includes at least one of sodium sulfite, E51, vitamin C, ferrous sulfate and bleaching agent.

[0021] Furthermore, the method for mixing and reacting the titanium-silicon solution, polyether monomer, unsaturated carboxylic acid small monomer, initiator, reducing agent and water comprises: respectively dissolving the polyether monomer, unsaturated carboxylic acid small monomer and reducing agent in water to obtain polyether monomer solution, unsaturated carboxylic acid small monomer solution and reducing agent solution, uniformly mixing the polyether monomer solution with the initiator and the titanium-silicon solution, and then dropwise adding the unsaturated carboxylic acid small monomer solution and the reducing agent solution thereto, reacting for 1 to 4 hours after the dropwise addition is completed, and then adding alkali solution to the reaction system to adjust the pH to 7 to 8.

[0022] The present invention further provides a titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent.

[0023] The present invention also provides application of the titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent in concrete products.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided by the present invention adopts a titanium-silicon solution containing a silane coupling agent to modify the polycarboxylic acid water-reducing agent. The prepared titanium-doped silica-modified polycarboxylic acid water-reducing agent has a high water reduction rate, good workability and collapse retention performance.

[0026] (2) The preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided by the present invention adopts a titanium-silicon solution to modify the polycarboxylic acid water-reducing agent, which can enhance the early strength of concrete.

[0027] (3) The titanium-doped silica-modified polycarboxylic acid water-reducing agent prepared by the preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided by the present invention can reduce the agglomeration of cement particles.

[0028] (4) The preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided by the present invention can improve the overall mechanical properties of concrete and improve the density and durability of concrete.

[0029] (5) The titanium-doped silica-modified polycarboxylic acid water-reducing agent prepared by the preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided by the present invention can effectively improve the bleeding of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the mechanism of the titanium-doped silica-modified polycarboxylate water-reducing agent and cement provided by the present invention;

[0032] Figure 2 This is an infrared comparison diagram of the titanium-doped silicon dioxide solutions obtained in Examples 1 to 5 provided by the present invention;

[0033] Figure 3 for Figure 2 A partial enlarged schematic diagram of . DETAILED DESCRIPTION

[0034] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0035] If there is no special explanation, in the present invention, "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", "the third", "the fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0036] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0037] If there is no special explanation, in the present invention, "one or more" or "at least one" refers to any one, any two or more of the listed items. Among them, "several" refers to any two or more of the listed items.

[0038] In a first aspect, the present invention provides a method for preparing a titanium-doped silica-modified polycarboxylate water-reducing agent, comprising the following steps:

[0039] The titanium source solution, silica sol and silane coupling agent are mixed and reacted to obtain a titanium-silicon solution (i.e., a titanium-doped silica solution), wherein the titanium-silicon solution contains a titanium-doped silica nanomaterial.

[0040] The titanium-silicon solution, polyether monomer, unsaturated carboxylic acid small monomer, initiator, reducing agent and water are mixed and reacted to obtain the titanium-doped silica modified polycarboxylic acid water reducer.

[0041] The invention provides a method for preparing a titanium-doped silica-modified polycarboxylate water-reducing agent, wherein a titanium-doped silica nanomaterial is used as a modifier of the polycarboxylate water-reducing agent to prepare the titanium-doped silica-modified polycarboxylate water-reducing agent, which can make concrete have higher water-reducing and slump-retaining performances.

[0042] Specifically, the present invention mainly utilizes the electrostatic repulsion between titanium-silicon solution and PCE (polycarboxylate water reducer) and the steric hindrance effect in silicon-titanium solution. The main mechanism of action is that the negatively charged polar groups in the polycarboxylate water reducer molecules modified by doping with silica tend to adsorb on the surface of positively charged cement particles, causing the Zeta potential value of the cement particle surface to change from positive to negative; at the same time, the long side chains of the comb-like structure of PCE face the outside of the cement, forming a water reducer adsorption layer around the cement particles, forcing the cement particles to generate repulsion, releasing more free water, and effectively increasing the fluidity of the slurry, ultimately achieving the purpose of water reduction. The schematic diagram of this mechanism is shown in Figure 1 shown.

[0043] The titanium-silicon solution used in the present invention has more accessible active sites. As the amount of grafting increases, the relative molecular weight of the water reducer gradually increases, the molecular chain grows, and the steric hindrance effect of the water reducer is further increased, the electrostatic repulsion between particles is enhanced, and the dispersibility is improved, which helps to improve the fluidity and uniformity of the concrete; under alkaline conditions, the Ti 4+ Able to enter SiO 2It forms Ti-O-Si bonds in the lattice of cement hydration products, which has a positive effect on refining the crystal structure of cement hydration products, improving the uniformity and density of hydration products, and thus enhancing the early strength of concrete.

[0044] The silane coupling agent used in the present invention is an organic silicon compound, and its hydrolysis product (≡Si-OH) forms a silicon-oxygen bond with the hydroxyl group (-OH) on the surface of cement particles, condenses to generate a certain amount of free water, improves workability and delays the cement hydration process, thereby improving the collapse resistance of concrete.

[0045] The titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the present invention contains hydroxyl groups and Ti-O-Si functional groups on the main chain of the PCE modified by the titanium-silicon solution, which can improve the interface bonding between the cement paste and the aggregate, and improve the density and strength of the interface transition zone, which is helpful to improve the overall mechanical properties of the concrete; on the other hand, by improving the interface performance, the porosity in the concrete is reduced, and the density and durability of the concrete are improved.

[0046] Therefore, the titanium-doped nano-silicon dioxide modified polycarboxylate water reducer prepared by the present invention has better water reduction rate and slump retention performance, makes concrete less likely to bleed, and has higher compressive strength, thus solving the problem of slow release in the early stage and poor retention in the later stage of traditional water reducers.

[0047] In addition, the skeleton of titanium-doped silica is electrically neutral and does not require ion charge compensation. The pores preferentially adsorb non-polar or low-polar organic molecules and are hydrophobic. The reaction mechanism is that during the doping process, a portion of the titanium ions (Ti 4+ ) replace part of Si 4+ position, or in a certain lattice gap, so that Ti 4+ Able to enter SiO 2 In the lattice, Ti-O and Si-O bonds are converted into Ti-O-Si bonds. Titanium-doped silica has a high specific surface area and surface activity, which adjusts the charge distribution on the surface of cement particles, increases the electrostatic repulsion between particles, and thus reduces the agglomeration of cement particles. It improves the interfacial bonding between cement paste and aggregate, increases the density and strength of the interface transition zone, helps to improve the overall mechanical properties of concrete, reduces the porosity in concrete, and improves the density and durability of concrete. The use of titanium-doped silica modified polycarboxylate water reducer can better disperse the cement particles inside the concrete, reduce the agglomeration of cement particles, reduce the friction between cement particles, reduce the bonding of concrete, reduce the viscosity of concrete, enhance the fluidity and workability of concrete, so that the contact area between concrete and water is increased, and the bubbles in the water are better dispersed, thereby increasing the density and durability of concrete. Therefore, the present invention solves the problem of the prior art using nano-SiO 2It is easy to cause cement particle agglomeration and directly introduce cement-based materials into the water-reducing agent to form competitive adsorption, which greatly reduces the working performance of cement-based materials.

[0048] In some specific embodiments, the molar ratio of the titanium element in the titanium source solution to the silicon element in the silica sol is 1:1 to 10, such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10. This titanium-silicon molar ratio has a higher water reduction rate.

[0049] In some specific implementations, the mass ratio of the silane coupling agent to the silica sol is 0.5 to 1:100, such as 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100 or 1:100. The use of the above amount of silane coupling agent can ensure the collapse resistance of concrete.

[0050] In some specific embodiments, the titanium source in the titanium source solution includes at least one of n-butyl titanate, tetraethyl titanate, titanium tetrachloride, and titanium trichloride.

[0051] In some specific embodiments, the solvent in the titanium source solution includes at least one of methanol, ethanol, and isopropanol.

[0052] For example, the titanium source solution includes an ethanol solution of n-butyl titanate, referred to as TBT alcohol solution.

[0053] In some specific embodiments, the method for preparing the ethanol solution of n-butyl titanate includes: mixing TBT and anhydrous ethanol and stirring the mixture at a speed of 600 to 1000 rpm until the solution becomes clear.

[0054] In some specific embodiments, the mass ratio of the titanium source to the solvent in the titanium source solution is 1:2 to 5, for example, 1:2, 1:3, 1:4 or 1:5.

[0055] In some specific embodiments, the silane coupling agent includes at least one of aminosilane, epoxysilane and thiosilane, such as A-1160, KH550, KH590 silane coupling agent, etc., but not limited thereto. The use of the above-mentioned types of silane coupling agents can ensure the collapse resistance of concrete.

[0056] In some specific embodiments, the method for mixing and reacting the titanium source solution, silica sol and silane coupling agent includes: mixing and stirring the titanium source solution and the silica sol, freezing them to a smoothie state, then stirring and thawing, and repeating the freezing-thawing process at least three times, adding the silane coupling agent thereto, and stirring at 60-100°C (e.g., 70°C, 80°C or 90°C) for 4-12h (e.g., 5h, 6h, 8h or 10h).

[0057] More specifically, the titanium-silicon solution of the present invention is prepared by slowly adding a titanium source solution to a silica sol and stirring for 2 to 4 hours, using a sol-gel method to prepare a stable titanium-silicon mixed solution, then transferring the titanium-silicon mixed solution to a three-necked flask, adding a silane coupling agent, heating, and continuing to stir. After cooling to room temperature, a titanium-silicon solution is obtained.

[0058] The preparation method of titanium-silicon solution is a sol-gel method. In the present invention, the mixture of titanium source solution and silica sol is frozen into a smoothie state and physically stirred to thaw, which can improve the dispersibility of titanium ions, slow down the activity of silica sol, and obtain a silicon-titanium solution with uniform titanium and silicon dispersion and relatively stable.

[0059] In some specific embodiments, the mass ratio of the titanium-silicon solution, the polyether monomer, the unsaturated carboxylic acid small monomer, the reducing agent and the initiator is 4-10 (e.g., 5, 6, 7, 8 or 9): 250-350 (e.g., 260, 280, 300, 320 or 330): 30-50 (e.g., 35, 38, 40, 42, 45 or 47): 0.3-1 (e.g., 0.4, 0.5, 0.6, 0.7, 0.8): 1-4 (e.g., 1.5, 2, 2.5, 3 or 3.5). The above ratio can improve the water reduction and collapse retention performance.

[0060] In some specific embodiments, the polyether monomer includes ethylene glycol polyoxyethylene ether (EPEG).

[0061] In some specific embodiments, the unsaturated carboxylic acid small monomer includes at least one of acrylic acid and methacrylic acid.

[0062] In some specific embodiments, the initiator includes at least one of hydrogen peroxide, sodium persulfate, ammonium persulfate and potassium persulfate.

[0063] In some specific embodiments, the reducing agent includes at least one of sodium sulfite, E51 (produced by Bruegmann of Germany), vitamin C, ferrous sulfate and bleaching powder (sodium formaldehyde sulfoxylate).

[0064] In some specific embodiments, the method of mixing and reacting the titanium-silicon solution, polyether monomer, unsaturated carboxylic acid small monomer, initiator, reducing agent and water includes: dissolving the polyether monomer, unsaturated carboxylic acid small monomer and reducing agent in water respectively to obtain polyether monomer solution, unsaturated carboxylic acid small monomer solution and reducing agent solution, uniformly mixing the polyether monomer solution with the initiator and the titanium-silicon solution, and then dropwise adding the unsaturated carboxylic acid small monomer solution and the reducing agent solution thereto, reacting for 1 to 4 hours (for example, 2 hours or 3 hours) after the dropwise addition is completed, and then adding alkali solution to the reaction system to adjust the pH to 7 to 8 (for example, 7.1, 7.2, 7.3, 7.5 or 7.8).

[0065] In some specific implementations, the unsaturated carboxylic acid small monomer solution is added dropwise for 1 to 3 hours.

[0066] In some specific embodiments, the reducing agent solution is added dropwise for 1 to 3 hours.

[0067] In some specific embodiments, the reaction temperature after the dropwise addition is room temperature, for example, 15 to 30° C., but not limited thereto.

[0068] In some specific embodiments, the alkali solution includes at least one of a NaOH solution and a KOH solution, but is not limited thereto.

[0069] In a second aspect, the present invention provides a titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent.

[0070] The titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the invention can enhance the early strength of concrete, has better water reduction rate and slump retention performance, can improve the density, durability and overall mechanical properties of concrete, and can also reduce cement particle agglomeration.

[0071] In a third aspect, the present invention provides the use of the titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent in concrete products.

[0072] The titanium-doped silica-modified polycarboxylic acid water-reducing agent prepared by the invention can enhance the early strength of concrete, has better water reduction rate and slump retention performance, can improve the density, durability and overall mechanical properties of concrete, and can also reduce cement particle agglomeration. It can be used to produce various concrete products and is applied to the fields of construction, transportation, water conservancy, agriculture, electricity, etc., and has broad application prospects.

[0073] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0074] Example 1

[0075] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment comprises the following steps:

[0076] (1) n-butyl titanate and anhydrous ethanol in a mass ratio of 1:2.5 were mixed and stirred for 30 min to obtain a TBT alcohol solution. The TBT alcohol solution was slowly added dropwise to 100 g of silica sol (SiO 2 The titanium-silicon mixed solution was slowly poured into 0.75 g of KH550 silane coupling agent (i.e., the mass ratio of silane coupling agent to silica sol was 0.75:100), stirred at 80°C for 4 h, and then cooled to room temperature to obtain a titanium-doped silica solution.

[0077] (2) Weigh 300g of ethylene glycol polyoxyethylene ether and 63 parts of deionized water in a four-necked flask to prepare a bottom liquid A. Put 40g of acrylic acid and 28 parts of deionized water in a beaker to prepare a material B. Put 0.5g of E51 and 50 parts of deionized water in a beaker to prepare a material C. At room temperature (25°C), add 6g of the titanium-doped silica solution obtained in step (1) and 2g of hydrogen peroxide (mass fraction of 27.5%) to the prepared bottom liquid A, respectively, stir for 8 minutes, and then uniformly add the prepared materials B and C thereto, wherein the dropping time of material B is 1h, and the dropping time of material C is 1.5h. After the dropping is completed, continue to react for 1 hour, and then adjust the pH value of the reaction system to 7 with NaOH solution to obtain a titanium-doped silica modified polycarboxylic acid water reducer.

[0078] Example 2

[0079] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment is basically the same, except that, in step (1), a corresponding amount of TBT alcohol solution is slowly added dropwise to 100 g of silica sol according to a molar ratio of titanium element to silicon element of 1:3.

[0080] Example 3

[0081] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment is basically the same, except that, in step (1), a corresponding amount of TBT alcohol solution is slowly added dropwise to 100 g of silica sol according to a molar ratio of titanium element to silicon element of 1:5.

[0082] Example 4

[0083] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment is basically the same, except that, in step (1), a corresponding amount of TBT alcohol solution is slowly added dropwise to 100 g of silica sol according to a molar ratio of titanium element to silicon element of 1:7.

[0084] Example 5

[0085] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment is basically the same, except that, in step (1), a corresponding amount of TBT alcohol solution is slowly added dropwise to 100 g of silica sol according to a molar ratio of titanium element to silicon element of 1:9.

[0086] Example 6

[0087] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment is basically the same, except that in step (1), the mass of the KH550 silane coupling agent is replaced with 1 g (ie, the mass ratio of the silane coupling agent to the silica sol is 1:100).

[0088] Example 7

[0089] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment is basically the same, except that in step (1), the KH550 silane coupling agent is replaced with an equal mass of A-1160 silane coupling agent.

[0090] Example 8

[0091] The preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided in this embodiment is basically the same, except that in step (2), acrylic acid is replaced by methacrylic acid of equal mass.

[0092] Example 9

[0093] The preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided in this embodiment is basically the same, except that in step (2), the hydrogen peroxide is replaced by an equal mass of sodium persulfate, and E51 is replaced by an equal mass of ferrous sulfate.

[0094] Example 10

[0095] The preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided in this embodiment is basically the same, except that in step (2), the hydrogen peroxide is replaced by an equal mass of ammonium persulfate, and E51 is replaced by an equal mass of bleaching powder.

[0096] Embodiment 11

[0097] The preparation method of the titanium-doped silica-modified polycarboxylic acid water-reducing agent provided in this embodiment is basically the same, except that in step (2), the mass of the titanium-doped silica solution is replaced with 10 g.

[0098] Example 12

[0099] The preparation method of the titanium-doped silica modified polycarboxylic acid water-reducing agent provided in this embodiment is basically the same, except that in step (2), except for the solvent water, the masses of the raw materials are: 345g of ethylene glycol polyoxyethylene ether, 46g of acrylic acid, 1g of E51, 6g of titanium-doped silica solution and 3g of hydrogen peroxide (the concentration of hydrogen peroxide is the same as that in Example 1).

[0100] Comparative Example 1

[0101] The preparation method of the polycarboxylate water-reducing agent provided in this comparative example is basically the same, except that step (1) is not performed, and titanium-doped silica solution is not added in step (2).

[0102] Comparative Example 2

[0103] The preparation method of the polycarboxylate water-reducing agent provided in this comparative example is basically the same, except that step (1) is not performed, and in step (2), the titanium-doped silica solution is replaced by an equal mass of silica sol.

[0104] Comparative Example 3

[0105] The polycarboxylate water-reducing agent provided in this comparative example is a commercially available polycarboxylate water-reducing agent of a certain company.

[0106] Comparative Example 4

[0107] The preparation method of the polycarboxylate water-reducing agent provided in this comparative example is basically the same, except that, in step (1), a corresponding amount of TBT alcohol solution is slowly added dropwise to 100 g of silica sol according to a molar ratio of titanium element to silicon element of 2:1.

[0108] Experimental example

[0109] According to the requirements of GB / T 8077-2012 "Test method for homogeneity of concrete admixtures", cement, water and titanium-doped silica-modified polycarboxylate water-reducing agent (or polycarboxylate water-reducing agent) were mixed, and the titanium-doped silica-modified polycarboxylate water-reducing agent prepared in each embodiment was compared with the polycarboxylate water-reducing agent of each comparative example in mortar performance test. The results are shown in Table 1.

[0110] Table 1 Water reduction rate results of each group

[0111]

[0112]

[0113] Combined with Table 1, by comparing the titanium-doped silica-modified polycarboxylate water-reducing agent (each embodiment) prepared by the present invention, the ordinary polycarboxylate water-reducing agent (Comparative Example 1), the silica-modified polycarboxylate water-reducing agent (Comparative Example 2) and the commercially available polycarboxylate water-reducing agent, it can be seen that the titanium-doped silica-modified polycarboxylate water-reducing agent (each embodiment) prepared by the present invention has a higher water reduction rate.

[0114] Among them, Examples 1 to 5 are polycarboxylic acid water reducers modified with different titanium-silicon ratios. It can be seen from the water reduction rate results that the water reduction rate gradually increases with the increase of the silicon-titanium ratio. When the titanium-silicon ratio is 1:5 (Example 3), the water reduction rate reaches a peak of 33.25%, and then decreases. This is because the molar ratio of Ti is low and it is difficult to meet the coordination requirements of the active sites.

[0115] This is consistent with the FT-IR image ( Figure 2 and Figure 3 ) has the same pattern, among which 3460.5cm -1 It is the antisymmetric stretching vibration of Si-OH or Ti-OH hydroxyl, 1632.8cm -1 It is HOH bending vibration, 1000~1250cm -1 The strong and broad absorption peak is the Si-O-Si antisymmetric stretching vibration, 969.8 cm -1 is Si-O-Ti stretching vibration, 799.2cm -1 and 471.6cm -1 It is Si-O symmetrical stretching vibration and bending vibration. 969.7cm -1 The absorption peak indicates that the Ti species in the silicon-titanium molecular sieve exists in the form of framework coordination. As the silicon-titanium ratio increases, the carrier 969.7cm -1 The absorption peak intensity gradually weakens and begins to weaken when the silicon-titanium ratio is greater than 5:1.

[0116] However, in Comparative Example 4, the water reduction rate was significantly decreased due to the inappropriate titanium-silicon molar ratio.

[0117] The titanium-doped silica-modified polycarboxylate water-reducing agent prepared in the above-mentioned embodiments was compared with the polycarboxylate water-reducing agent in each comparative example in concrete performance test. The detection method was carried out in accordance with the method specified in GB / T50080-2002 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", and the concrete used was Conch PO 42.5 cement, and the C30 concrete test mix was shown in Table 2 below, and the expansion and compressive strength properties were shown in Table 3.

[0118] Table 2 Concrete mix ratio (kg / m 3 )

[0119]

[0120]

[0121] Table 3 Concrete properties of various polycarboxylate water reducers (solid content: 0.16%)

[0122]

[0123] It can be seen from Table 3 that when the solid content is 0.16%, compared with Comparative Examples 1 to 4, the titanium-doped silica modified polycarboxylic acid water-reducing agents prepared in various embodiments of the present invention have better workability and collapse retention performance, and the compressive strength of 3 days (3d) and 28 days (28d) also has a higher advantage.

[0124] The solid content of Example 2, Example 3, Example 4 and Comparative Example 1 was further increased to 0.19%, and concrete performance tests and working status comparisons were conducted, as shown in Table 4.

[0125] Table 4 Concrete properties of various polycarboxylic acid water reducing agents (solid content: 0.19%)

[0126]

[0127]

[0128] It can be seen from Table 4 that when the solid content is increased to 0.19%, the concrete state of the titanium-doped silica-modified polycarboxylate water-reducing agent prepared in Examples 2 to 4 of the present invention is better, while the ordinary polycarboxylate water-reducing agent (Comparative Example 1) has bleeding. It can be seen that the titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the present invention can also effectively improve the bleeding of concrete.

[0129] In summary, the titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the preparation method of the titanium-doped silica-modified polycarboxylate water-reducing agent provided by the present invention has a high water reduction rate, good workability and slump retention performance, and improved mechanical strength and durability, and improved water seepage. In addition, the use of the titanium-doped silica-modified polycarboxylate water-reducing agent can better disperse the cement particles inside the concrete and reduce the agglomeration of cement particles.

[0130] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a titanium-doped silica-modified polycarboxylate water-reducing agent, characterized in that: The steps include: The titanium source solution, silica sol and silane coupling agent are mixed and reacted to obtain a titanium-silicon solution; The titanium-silicon solution, polyether monomer, unsaturated carboxylic acid small monomer, initiator, reducing agent and water are mixed and reacted to obtain the titanium-doped silica modified polycarboxylic acid water reducer.

2. The method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to claim 1, characterized in that: At least one of the following conditions is met: (1) The molar ratio of the titanium element in the titanium source solution to the silicon element in the silica sol is 1:1 to 10; (2) The mass ratio of the silane coupling agent to the silica sol is 0.5 to 1:

100.

3. The method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to claim 1, characterized in that: At least one of the following conditions is met: (1) The titanium source in the titanium source solution includes at least one of n-butyl titanate, tetraethyl titanate, titanium tetrachloride and titanium trichloride; (2) The solvent in the titanium source solution includes at least one of methanol, ethanol and isopropanol.

4. The method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to claim 1, characterized in that: The silane coupling agent includes at least one of aminosilane, epoxysilane and thiosilane.

5. The method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to claim 1, characterized in that: The method for mixing and reacting the titanium source solution, silica sol and silane coupling agent comprises: mixing and stirring the titanium source solution and the silica sol, freezing them to a smoothie state, then stirring and thawing, and repeating the freezing-thawing process at least three times, then adding the silane coupling agent thereto, and stirring at 60-100° C. for 4-12 hours.

6. The method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to any one of claims 1 to 5, characterized in that: The mass ratio of the titanium-silicon solution, the polyether monomer, the unsaturated carboxylic acid small monomer, the reducing agent and the initiator is 4-10: 250-350: 30-50: 0.3-1: 1-4.

7. The method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to any one of claims 1 to 5, characterized in that: At least one of the following conditions is met: (1) The polyether monomer includes vinyl glycol polyoxyethylene ether; (2) the unsaturated carboxylic acid small monomer comprises at least one of acrylic acid and methacrylic acid; (3) The initiator comprises at least one of hydrogen peroxide, sodium persulfate, ammonium persulfate and potassium persulfate; (4) The reducing agent includes at least one of sodium sulfite, E51, vitamin C, ferrous sulfate and bleaching agent.

8. The method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to any one of claims 1 to 5, characterized in that: The method for mixing and reacting the titanium-silicon solution, polyether monomer, unsaturated carboxylic acid small monomer, initiator, reducing agent and water comprises: respectively dissolving the polyether monomer, unsaturated carboxylic acid small monomer and reducing agent in water to obtain polyether monomer solution, unsaturated carboxylic acid small monomer solution and reducing agent solution, uniformly mixing the polyether monomer solution with the initiator and the titanium-silicon solution, and then dropwise adding the unsaturated carboxylic acid small monomer solution and the reducing agent solution thereto, reacting for 1 to 4 hours after the dropwise addition is completed, and then adding alkali solution into the reaction system to adjust the pH to 7 to 8.

9. The titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to any one of claims 1 to 8.

10. Use of the titanium-doped silica-modified polycarboxylate water-reducing agent prepared by the method for preparing the titanium-doped silica-modified polycarboxylate water-reducing agent according to any one of claims 1 to 8 in concrete products.

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