Preparation method of Portland cement hydration product modifier

Abstract

The invention relates to a preparation method of a modifier for a hydration product of Portland cement, the modifier mainly comprises the following raw materials: a polyphenol compound, a polyamine compound, a polysaccharide compound, an amino silane compound and the like, and the polyphenol compound is coupled under the action of oxidation and catalysis to form a dimer; the preparation method comprises the following steps: carrying out Michael addition reaction, connecting with a polyamine compound to form a polymer, respectively reacting with an amino silane compound and a modified polysaccharide compound, and grafting the amino silane compound and the modified polysaccharide compound on the polymer to obtain the Portland cement hydration product modifier. The Portland cement hydration product modifier prepared by the invention has the characteristics of simple and controllable process, wide raw material source, excellent performance and the like, can generate intercalation and other effects with cement hydration products after being doped into cement paste, gives full play to the advantage of internal and external synergy, fundamentally changes the characteristics of the hydration products, and has a good application prospect. The effects of mechanical enhancement, shrinkage inhibition and the like of the concrete are realized on the macroscopic level, and the concrete shows excellent application potential and development prospect.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of cement-based materials, and in particular to a modifier of silicate cement hydration products and a preparation method thereof. Background Art

[0002] As the most widely used building material in the world, concrete shrinks during the setting and hardening process. A large number of studies have shown that concrete shrinkage is the main cause of defects such as cracking. Concrete cracking affects the appearance and structural integrity, and also causes deformation of concrete components, affecting the stability and service life of the overall structure, seriously reducing durability, and posing great safety hazards. In order to solve this problem, the use of excellent shrinkage reducing agents can effectively reduce the early shrinkage of cement-based materials and extend their service life. In recent years, with the increasing requirements for shrinkage reducing agents, the development of excellent shrinkage reducing agents has become a key technical problem in the preparation of high-performance concrete.

[0003] Although the research on concrete shrinkage reducers has been developed for many years, there are still many problems in the preparation and application of shrinkage reducers. For example, carbon nanotubes can improve shrinkage reduction performance and mechanical properties, but due to their high price cost, it is still difficult to achieve large-scale application. Some other shrinkage reducers with excellent performance have high dangerous raw materials, which are potentially harmful to users and difficult to put into actual production and application. The shrinkage reducer of the present invention is a modifier of silicate cement hydration products, which is a polymer made of polyphenol compounds and polyamine compounds produced by plant metabolism as basic raw materials, and is grafted with amino silane compounds and polysaccharides with high water retention through side chains to achieve overall modification of silicate cement hydration products, which can effectively improve the shrinkage reduction performance and mechanical properties of concrete.

[0004] Patent CN111533856A (publication date: August 14, 2020) reports an organic shrinkage reducer and its preparation method and application. The shrinkage reducer is prepared from allyl polyoxyethylene ether, polyethylene glycol monooleate, maleic anhydride, N-hydroxymethyl acrylamide, benzoyl peroxide, and chain transfer agent. The organic shrinkage reducer has the function of reducing shrinkage, which can reduce shrinkage cracking of concrete and improve the durability and service life of concrete. At the same time, the viscosity of concrete can be reduced, the slurry is soft, and it is easy to vibrate and discharge bubbles. It has a higher surface cleanliness after demolding, but the introduced polyethylene glycol monooleate belongs to the molecular structure design of traditional shrinkage reducers, and fails to achieve molecular structure innovation from the perspective of green and low-carbon biomass or branched structure.

[0005] Patent CN111592271A (publication date: August 28, 2020) reports a concrete-admixed anti-seepage and anti-cracking shrinkage-reducing agent and its preparation method, which includes the following components by weight: 35-45 parts by weight of alkali-modified diatomaceous earth, 15-22 parts by weight of magnesium oxide, 13-20 parts by weight of vermiculite, 8-11 parts by weight of borax, 3-9 parts by weight of sodium hexametaphosphate, and 7-13 parts by weight of citric acid-modified starch. The shrinkage-reducing agent is applied to concrete as an admixture to improve the working performance of fresh concrete, reduce concrete shrinkage, and improve the mechanical properties and durability of hardened concrete. However, in its preparation process, modified diatomaceous earth, starch, borax, sodium hexametaphosphate and vermiculite need to be fully mixed and ground to a particle size of less than 40 μm, which is heavily dependent on the particle size quality of ultrafine powder and is difficult to be applied on a large scale in industry.

[0006] Patent CN112830704A (publication date: May 25, 2021) reports an ultra-high performance concrete shrinkage reducer and a preparation method thereof. The shrinkage reducer is prepared from maleic anhydride, polyethylene glycol and its derivatives, polypropylene glycol and its derivatives through esterification, polymerization and other reactions. The shrinkage reducer has a significant inhibitory effect on the early plastic shrinkage of concrete, has no significant effect on the setting time, and can be used in conjunction with polycarboxylic acid water reducers. However, its working principle still belongs to the traditional category of dependence on polyethylene / propylene glycol derivatives, and has failed to achieve real modification and breakthroughs in cement hydration products at the microscopic level.

[0007] The shrinkage reducing agent mentioned in the above patent has shown certain effects in reducing concrete shrinkage and improving mechanical properties. However, there are still some areas for improvement in its preparation method. In the process of seeking to optimize the shrinkage reduction effect and mechanical properties, the operating methods adopted by current researchers are relatively complicated, which is not conducive to large-scale promotion and application. At the same time, its research and development ideas are still limited to the physical compounding or grinding of multiple substances, or the introduction of polyethylene glycol derivatives, and innovations in molecular structure design and other aspects are in urgent need of breakthroughs. In addition, in terms of innovative design of shrinkage reduction mechanism, most researchers are still limited to traditional methods such as changing the properties of cement pore solution. In fact, the main hydration product of silicate cement is CSH, and there is currently a lack of technical innovation for CSH modification to achieve macro-level shrinkage reduction of concrete. In the preparation process of shrinkage reducing agents, it is necessary to introduce innovative molecular structure design concepts. Based on fine molecular structure design and combined with advanced synthesis methods, it is not limited to traditional molecular structures. Polyphenols and polyamines can generate macromolecules through Michael addition reaction, and then organosilane and polysaccharide compounds are grafted to their side chains through Schiff base reaction, so that the polymer can stably exist between the hydrated calcium silicate layers, fully block the moisture inside the cement hydration product, and show excellent water control effect, thereby effectively inhibiting the shrinkage of concrete. This preparation method is simple and convenient, with novel principles, excellent effects, and relatively low cost. It has broad development space and extremely high industrial production value. No research in this area has been reported at home and abroad. Summary of the invention

[0008] The purpose of the present invention is to provide a preparation method of a silicate cement hydration product modifier, which adopts polyphenol compounds, polyamine compounds, polysaccharide compounds and aminosilane compounds as main raw materials, couples the polyphenol compounds to form dimers under the action of oxidation and catalysis, connects the polyphenol compounds with polyamine compounds through Michael addition reaction to form polymers, and then reacts with aminosilane compounds to graft them, and finally grafts the modified polysaccharide compounds onto the polymer through acylation reaction to obtain the silicate cement hydration product modifier. The invention is based on the theory of molecular structure design, innovatively polymerizes and connects polyphenol compounds through polyamine compounds, and then respectively grafts aminosilane compounds and modified polysaccharide macromolecules on the main chain, wherein the aminosilane part in the polymer molecule is embedded in the Si-O layer structure of CSH during the formation process of the cement hydration product CSH, and forms a tight connection with CSH, thereby ensuring the intercalation stability of the polymer molecule and closing the channel for water escape, thereby achieving the purpose of shrinkage reduction and modification of CSH, and at the same time, the main body of the polymer molecule points to the water-containing Ca-O layer between the CSH layers, and the phenolic hydroxyl group of the polyphenol compound in the structure can be complexed with the Ca-O layer of the cement hydration product through complexation. 2+Further anchoring and synergistically improving the rigidity of the CSH structure with the silane structure, thereby achieving the effect of both concrete reduction and enhancement, showing a more innovative design concept than traditional concrete shrinkage reducers, as well as more excellent effects and broader development prospects.

[0009] The present invention provides a method for preparing a modifier for silicate cement hydration products. The conditions and steps for preparing the modifier for silicate cement hydration products are as follows:

[0010] (1) Preparation of polyphenol dimer: prepare a polyphenol compound into an aqueous solution with a mass fraction of 10-20%, adjust the solution pH to 8-14, heat to 40-80° C., continuously introduce oxygen, add a catalyst, stir at a constant temperature for 6-12 hours, cool to room temperature, and filter to obtain a polyphenol dimer solution;

[0011] (2) Michael addition: add the polyphenol dimer solution obtained in step (1) into a reactor, adjust the solution pH to 8-14, stir and heat to 30-50° C., continuously introduce oxygen, and under stirring conditions, dropwise add a polyamine aqueous solution with a mass fraction of 8-12% into the reactor within 4-8 hours, stir and react at a constant temperature for 1-3 hours, and cool to room temperature after the reaction to obtain a Michael addition product;

[0012] (3) Grafting reaction: add the Michael addition obtained in step (2) to a reactor, adjust the pH value of the solution to 8-10, continuously introduce oxygen at room temperature, and dropwise add a 10-20% aminosilane aqueous solution into the reactor under stirring for 4-6 hours, stir and react at a constant temperature for 1-3 hours, and adjust the pH value of the solution to 4-7 after the reaction to obtain a grafted product solution;

[0013] (4) Preparation of modified polysaccharide compounds: Add polysaccharide compounds, thionyl chloride and catalyst into a reactor, stir and heat to 50-70° C., continuously introduce nitrogen, react for 9-12 hours, distill under reduced pressure and dry to obtain modified polysaccharide compounds;

[0014] (5) Acylation reaction: adding the grafted product solution obtained in step (3), a catalyst and a solvent into a reactor, continuously introducing nitrogen at room temperature, and dripping a 5-10% by mass aqueous solution of the modified polysaccharide compound obtained in step (4) into the reactor under stirring for 8-14 hours, stirring and reacting at a constant temperature for 1-3 hours, and distilling under reduced pressure after the reaction is completed, washing, and vacuum drying at 100-140° C. to obtain a silicate cement hydration product modifier;

[0015] Wherein, the polyphenol compound in step (1) is tannic acid or baicalein; the catalyst in step (1) is manganese dioxide, potassium ferrate or potassium ferrocyanate, and the mass ratio of the catalyst to the polyphenol compound in step (1) is 0.05-0.1:1;

[0016] The solute of the polyamine aqueous solution in step (2) is urea, ethylenediamine or propylenediamine, and the molar ratio of the polyamine aqueous solution to the polyphenol compound in step (1) is 0.4-0.6:1;

[0017] The solute of the aminosilane aqueous solution in step (3) is γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane or N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, and the molar ratio of the solute of the polyamine aqueous solution in step (2) is 1-1.2:1;

[0018] The polysaccharide compound in step (4) is hyaluronic acid or acetylated hyaluronic acid, and the molar ratio of the polysaccharide compound in step (1) is 0.4-0.6:1; the molar ratio of the thionyl chloride to the polysaccharide compound is 2-4:1; the catalyst in step (4) is N,N-dimethylformamide or pyridine, and the mass ratio of the catalyst to the polysaccharide compound is 0.01-0.05:1;

[0019] The catalyst in step (5) is N,N-dimethylformamide or pyridine, and the mass ratio of its usage to the solute in the grafted product solution in step (3) is 0.05-0.1:1; the solvent in step (5) is tetrahydrofuran or dimethylacetamide, and the mass ratio of its usage to the solute in the grafted product solution in step (3) is 2.5-5:1; the molar ratio of the solute usage of the modified polysaccharide compound aqueous solution obtained in step (4) in step (5) to the solute in the polyamine aqueous solution in step (2) is 0.8-1:1.

[0020] The molecular structural formula of the silicate cement hydration product modifier described in step (5) of the method of the present invention is as follows:

[0021]

[0022] Where R1 is R2 is carbonyl, ethyl or propyl; R3 is propyl or propylaminoethyl; R4 is hydrogen or acetyl;

[0023] Wherein m and n are positive integers, representing the number of repeating units of each part in the polymer, m ranges from 5-10, and n ranges from 500-2000.

[0024] The invention also provides application of the silicate cement hydration product modifier in concrete.

[0025] In the present invention, the concrete includes the following components in mass fractions: mixture A, mixture B, sand, and gravel.

[0026] Mixture A includes polycarboxylate water-reducing agent, silicate cement hydration product modifier, ordinary silicate cement and water; in mixture A, the content of silicate cement hydration product modifier is 0.1-0.3% of cement, the content of polycarboxylate water-reducing agent is 0.29% of cement, and the amount of water added is 10-20% of the total cementitious materials;

[0027] Mixture B is composed of other cementitious materials, silicate cement hydration product modifier and water; in mixture B, other cementitious materials are fly ash and mineral powder, the content of silicate cement hydration product modifier is 0.1-0.2% of other cementitious materials, and the amount of water added is 10-15% of the total cementitious materials.

[0028] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0029] 1. The present invention starts from the innovative design concept of molecular structure, connects polyphenol compounds and polyamine compounds to each other through the "Michael addition" reaction to form a long-chain polymer, and then introduces aminosilane compounds on the main chain through the "covalent grafting" method, and finally introduces modified polysaccharide macromolecules on the main chain through the "acylation" method, which opens up the design concept of concrete shrinkage reducers. Among them, the molecular structures of polyphenols and polysaccharide compounds can improve the water retention of concrete, and the synergy of the two can further ensure the full hydration of cement particles in the system, reduce water loss, and play the effect of improving the strength of concrete and reducing concrete shrinkage.

[0030] 2. The polysaccharide compound raw materials used in the present invention have the advantages of wide sources, excellent water retention performance, controllable molecular weight, low cost, etc. After modification, they are introduced into the molecular structure of the prepared product. The new materials developed are in line with the national "green and low-carbon" and "sustainable development" strategies, give full play to the performance advantages of natural plant raw materials, have a significant promoting effect on improving the shrinkage reduction performance of concrete, and have excellent performance stability.

[0031] 3. Compared with traditional shrinkage reducing agents, the mechanism of action designed in the present invention is significantly innovative. In the process of forming the cement hydration product CSH, the aminosilane part in the polymer molecule can be embedded in the Si-O layer structure of CSH, and intercalated in CSH to form a tight connection. This connection mode not only ensures the intercalation stability of the polymer molecules, but also gives CSH a certain rigidity, closes the channel for the escape of internal water, and thus realizes the mechanical enhancement modification and shrinkage inhibition modification of CSH. In addition, the main part of the polymer molecule points to the water-containing Ca-O layer between the CSH layers, and the phenolic hydroxyl groups of the polyphenol compounds in its structure can react with the Ca-O layer of the cement hydration product through complexation. 2+ Further anchoring, synergistically with the silane structure, jointly improves the rigidity of the CSH microstructure. In addition, the hydroxyl groups of polyphenolic compounds and polysaccharide compounds, as well as the nitrogen atoms of polyamine compounds in the polymer molecules, can form hydrogen bonds with interlayer water, effectively limiting the migration of water molecules between layers, thereby achieving the effect of reducing shrinkage. The above mechanisms of action enable the modifier developed by the present invention to show excellent effects in both mechanical enhancement and shrinkage reduction.

[0032] 4. Compared with the traditional shrinkage reducing agent preparation method, the modifier prepared by this method abandons raw materials such as polyethylene / propylene glycol derivatives, uses a variety of simple and common substances to participate in the reaction, and the Michael addition, covalent grafting, acylation reaction and other steps introduced by the design are all common preparation methods. No special experimental equipment and preparation process are required, which greatly reduces the preparation cost while realizing the comprehensiveness and multifunctionality of the reaction products.

[0033] 5. In the field of engineering applications, the preparation process of the silicate cement hydration product modifier developed by the present invention is simple and controllable, energy-saving and efficient, and has the characteristics of low toxicity and high safety. It is easy to realize industrial production, and its application in concrete is also beneficial to extend the service life of concrete, improve the construction quality of construction projects, and significantly improve economic benefits, social benefits and environmental benefits. It has huge market potential and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the XRD pattern of the modifier of silicate cement hydration product added to CSH;

[0035] Figure 2 This is the infrared spectrum of the modifier of silicate cement hydration products.

[0036] The present invention is further described in detail below in conjunction with embodiments, but the implementation of the present invention is not limited thereto.

[0037] Example 1

[0038] First, 170.1 g of tannic acid and 680.4 g of distilled water were added to a reactor, a 20% sodium hydroxide solution was added, the pH value was adjusted to 8, the mixture was stirred and heated to 50°C, oxygen was continuously introduced during the reaction, 8.5 g of manganese dioxide was added to the reactor, the mixture was stirred at a constant temperature for 6 hours, the reaction was cooled to room temperature after completion, and a tannic acid dimer solution was obtained after filtration; the tannic acid dimer solution was placed in a reactor, a 20% sodium hydroxide solution was added, the pH value was adjusted to 8, the mixture was stirred and heated to 30°C, oxygen was continuously introduced during the reaction, 2.4 g of urea and 27.6 g of distilled water were prepared into an 8% solution, the solution was added dropwise to the reactor for 4 hours, the mixture was stirred at a constant temperature for 1 hour, oxygen was continuously introduced after completion of the reaction, 8.5 g of manganese dioxide was added to the reactor, the mixture was stirred at a constant temperature for 6 hours, oxygen was continuously introduced after completion of the reaction, and 8.5 g of manganese dioxide was added to the reactor, the mixture was stirred at a constant temperature for 6 hours, the reaction was cooled to room temperature after completion, and a Michael addition product was obtained; the Michael addition product was placed in a reactor, a 40% sodium hydroxide solution was added, the pH value was adjusted to 10, oxygen was continuously introduced at room temperature, and 8.5 g of manganese dioxide was added to the reactor, the mixture was stirred at a constant temperature for 6 hours, the reaction was cooled to room temperature after completion, and a Michael addition product was obtained. 9g of γ-aminopropyltriethoxysilane and 65.3g of distilled water were prepared into a 12% mass fraction solution, which was added dropwise to the reactor for 6 hours, stirred at a constant temperature for 2 hours, and a 5% mass fraction hydrochloric acid solution was added to adjust the pH value to 7 to obtain a grafted product solution; 19g of hyaluronic acid, 11.9g of dichlorothionyl and 0.2g of N,N-dimethylformamide were added to the reactor, stirred and heated to 50°C, nitrogen was continuously introduced during the reaction, and the reaction was stirred at a constant temperature for 9 hours. The grafted product solution, 9.1 g of pyridine and 453 g of tetrahydrofuran were added into the reactor, and nitrogen was continuously introduced at room temperature. 16.5 g of modified hyaluronic acid and 313.5 g of distilled water were added dropwise into the reactor at a mass fraction of 5% for 8 hours, and the mixture was reacted at a constant temperature for 3 hours. After the reaction, the mixture was distilled under reduced pressure, washed, and dried in vacuo at 100°C to obtain a silicate cement hydration product modifier. 0.69 g of silicate cement hydration product modifier and 1.02 g of polycarboxylate water reducer (commercially available from China Building Materials Zhongyan Technology Co., Ltd.) were added to 346 g of cement (PO·42.5 ordinary silicate cement) to obtain mixture A; 0.48 g of silicate cement hydration product modifier was added to 81 g of fly ash (first-grade fly ash) and 81 g of mineral powder (S105 mineral powder) to obtain mixture B; mixture A, mixture B, 705 g of sand (particle size ≤ 5 mm) and 1016 g of gravel (particle size ≤ 5 mm) were mixed and stirred to obtain concrete modified by silicate cement hydration products.

[0039] In this embodiment: R1 is R2 is a carbonyl group; R3 is a propyl group; and R4 is a hydrogen group.

[0040] Example 2

[0041] First, 27 g of baicalein and 153 g of distilled water were added to a reactor, and a 20% sodium hydroxide solution was added, and the pH value was adjusted to 10. The mixture was stirred and heated to 60°C. Oxygen was continuously introduced during the reaction. 2.2 g of potassium ferrate was added to the reactor, and the mixture was stirred at a constant temperature for 10 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain a baicalein dimer solution. The baicalein dimer solution was placed in a reactor, and a 20% sodium hydroxide solution was added. The pH value was adjusted to 10. The H value is 10, stirring and heating to 40°C, continuously passing oxygen during the reaction, 3g of ethylenediamine and 27g of distilled water are prepared into a 10% mass fraction solution, added dropwise for 6 hours into the reactor, stirred at a constant temperature for 2h, and cooled to room temperature after the reaction to obtain a Michael addition product; the Michael addition product is placed in a reactor, a 20% mass fraction sodium hydroxide solution is added, the pH value is adjusted to 8, oxygen is continuously passed at room temperature, 13.3g of γ-aminopropyltriethoxy Silane and 53.1g of distilled water were prepared into a 20% mass fraction solution, which was added dropwise to the reactor for 5 hours, stirred at a constant temperature for 1 hour, and a 20% mass fraction hydrochloric acid solution was added to adjust the pH value to 5 to obtain a grafted product solution; 32.8g of acetylated hyaluronic acid, 21.4g of dichlorothionyl and 1.6g of pyridine were added to the reactor, stirred and heated to 60°C, nitrogen was continuously introduced during the reaction, and the reaction was stirred at a constant temperature for 10 hours. After the reaction was completed, it was distilled under reduced pressure and dried. Modified acetylated hyaluronic acid is obtained; the grafted product solution, 3.5 g of N,N-dimethylformamide and 173.2 g of dimethylacetamide are added into a reactor, nitrogen is continuously introduced at room temperature, 29 g of modified acetylated hyaluronic acid and 333.5 g of distilled water are prepared into a solution with a mass fraction of 8%, and the solution is added dropwise for 10 hours into the reactor, and the solution is reacted at a constant temperature for 2 hours. After the reaction is completed, the solution is distilled under reduced pressure, washed, and vacuum dried at 100°C to obtain a silicate cement hydration product modifier. 1.04 g of a silicate cement hydration product modifier and 1.02 g of a polycarboxylate water reducer (commercially available from China Building Materials Zhongyan Technology Co., Ltd.) were added to 346 g of cement (PO·42.5 ordinary silicate cement) to obtain a mixture A; 0.33 g of a silicate cement hydration product modifier was added to 81 g of fly ash (first-grade fly ash) and 81 g of mineral powder (S105 mineral powder) to obtain a mixture B; and the mixture A, the mixture B, 705 g of sand (particle size ≤ 5 mm), and 1016 g of gravel (particle size ≤ 5 mm) were mixed and stirred to obtain concrete modified by silicate cement hydration products.

[0042] In this embodiment: R1 is R2 is ethyl; R3 is propyl; R4 is acetyl.

[0043] Example 3

[0044] First, 27 g of baicalein and 243 g of distilled water were added to a reactor, a 40% sodium hydroxide solution was added, the pH value was adjusted to 14, the mixture was stirred and heated to 40°C, oxygen was continuously introduced during the reaction, 1.4 g of potassium ferrocyanate was added to the reactor, the mixture was stirred at a constant temperature for 8 hours, the mixture was cooled to room temperature after the reaction was completed, and the baicalein dimer solution was obtained after filtration; the baicalein dimer solution was placed in a reactor, a 40% sodium hydroxide solution was added, the pH value was adjusted to 12, the mixture was stirred, and the mixture was heated to 40°C. The temperature was raised to 50° C., oxygen was continuously introduced during the reaction, 3.6 g of ethylenediamine and 29.2 g of distilled water were prepared into a 11% mass fraction solution, and the solution was added dropwise to the reactor for 8 hours to react, and the reaction was stirred at a constant temperature for 1 hour. After the reaction was completed, the solution was cooled to room temperature to obtain a Michael addition product; the Michael addition product was placed in a reactor, a 40% mass fraction sodium hydroxide solution was added, the pH value was adjusted to 10, oxygen was continuously introduced at room temperature, and 16.1 g of N-β (aminoethyl) -γ-aminopropyl Trimethoxysilane and 91.2g of distilled water were prepared into a 15% mass fraction solution, which was added dropwise to the reactor for 6 hours and stirred at a constant temperature for 3 hours. A 10% mass fraction hydrochloric acid solution was added and the pH value was adjusted to 6 to obtain a grafted product solution. 21.9g of acetylated hyaluronic acid, 28.5g of dichlorothionyl and 1.1g of N,N-dimethylformamide were added to the reactor, stirred and heated to 70°C. Nitrogen was continuously introduced during the reaction, and the reaction was stirred at a constant temperature for 12 hours. After the reaction was completed, reduced pressure distillation was performed. The mixture was dried to obtain modified acetylated hyaluronic acid; the grafted product solution, 4.6 g of N,N-dimethylformamide and 233.5 g of dimethylacetamide were added into the reactor, nitrogen was continuously introduced at room temperature, 27.9 g of modified acetylated hyaluronic acid and 251.1 g of distilled water were prepared into a 10% mass fraction solution, and the solution was added dropwise into the reactor for 14 hours, and the solution was reacted at a constant temperature for 2 hours. After the reaction, the solution was distilled under reduced pressure, washed, and dried in vacuum at 130°C to obtain a silicate cement hydration product modifier. 1.73 g of a silicate cement hydration product modifier and 1.02 g of a polycarboxylate water reducer (commercially available from China Building Materials Zhongyan Technology Co., Ltd.) were added to 346 g of cement (PO·42.5 ordinary silicate cement) to obtain a mixture A; 0.65 g of a silicate cement hydration product modifier was added to 81 g of fly ash (first-grade fly ash) and 81 g of mineral powder (S105 mineral powder) to obtain a mixture B; and the mixture A, the mixture B, 705 g of sand (particle size ≤ 5 mm), and 1016 g of gravel (particle size ≤ 5 mm) were mixed and stirred to obtain concrete modified by silicate cement hydration products.

[0045] In this embodiment: R1 is R2 is ethyl; R3 is propylaminoethyl; R4 is acetyl.

[0046] Example 4

[0047] First, 170.1g of tannic acid and 774.9g of distilled water are added to a reactor, a 40% sodium hydroxide solution is added, the pH value is adjusted to 12, the mixture is stirred and heated to 70°C, oxygen is continuously introduced during the reaction, 17g of manganese dioxide is added to the reactor, the mixture is stirred at a constant temperature for 12 hours, the reaction is cooled to room temperature after completion, and a tannic acid dimer solution is obtained after filtration; the tannic acid dimer solution is placed in a reactor, a 40% sodium hydroxide solution is added, the pH value is adjusted to 12, the mixture is stirred and heated to 50°C, oxygen is continuously introduced during the reaction, 3.6g of urea and 26.4g of distilled water are prepared into a 12% solution, the solution is added dropwise to the reactor for 6 hours, the mixture is stirred at a constant temperature for 2 hours, oxygen is continuously introduced after completion of the reaction, 13.3g of N-β (aminoethyl) -γ-aminopropyl trimethoxysilane and 53.2g of distilled water were prepared into a 20% solution by mass, which was added dropwise to the reactor for 5 hours, stirred at a constant temperature for 2 hours, and a 5% hydrochloric acid solution was added to adjust the pH value to 6 to obtain a grafted product solution; 22.7g of hyaluronic acid, 21.4g of dichlorothionyl and 1.2g of pyridine were added to the reactor, stirred and heated to 60°C, nitrogen was continuously introduced during the reaction, and the reaction was stirred at a constant temperature for 12 hours. After the reaction, the mixture was distilled under reduced pressure and dried to obtain modified hyaluronic acid; the grafted product solution, 18.7 g of pyridine and 561 g of tetrahydrofuran were added into the reactor, and nitrogen was continuously introduced at room temperature. 19.8 g of modified hyaluronic acid and 178.2 g of distilled water were prepared into a 10% mass fraction solution, which was added dropwise into the reactor for 12 hours, and the solution was reacted at a constant temperature for 3 hours. After the reaction, the mixture was distilled under reduced pressure, washed, and dried in vacuum at 120° C. to obtain a silicate cement hydration product modifier. 1.38 g of silicate cement hydration product modifier and 1.02 g of polycarboxylate water reducer (commercially available from China Building Materials Zhongyan Technology Co., Ltd.) were added to 346 g of cement (PO·42.5 ordinary silicate cement) to obtain mixture A; 0.41 g of silicate cement hydration product modifier was added to 81 g of fly ash (first-grade fly ash) and 81 g of mineral powder (S105 mineral powder) to obtain mixture B; mixture A, mixture B, 705 g of sand (particle size ≤ 5 mm) and 1016 g of gravel (particle size ≤ 5 mm) were mixed and stirred to obtain concrete modified by silicate cement hydration products.

[0048] In this embodiment: R1 is R2 is a carbonyl group; R3 is a propylaminoethyl group; and R4 is a hydrogen group.

[0049] Implementation effect:

[0050] 1. Effect of Portland cement hydration product modifier on CSH intercalation

[0051] The following results were obtained by XRD analysis of the silicate cement hydration product modifier with CSH added: Figure 1 It can be seen that when 2θ = 6.56°, the interlayer spacing of the 002 plane of CSH becomes larger, and the interlayer spacing of CSH increases with the increase of the concentration of the silicate cement hydration product modifier, indicating that the silicate cement hydration product modifier is inserted into the CSH interlayer, and the intercalation amplitude is proportional to the modifier concentration.

[0052] 2. Concrete shrinkage effect

[0053] The shrinkage test results of concrete are shown in Table 1. The dosage of the silicate cement hydration product modifier prepared by the present invention is fixed at 0.5% of the amount of cementitious material. The comparative example used is concrete without adding the silicate cement hydration product modifier, and the other components remain unchanged.

[0054] Table 1 Concrete shrinkage test results

[0055]

[0056]

[0057] It can be seen from the concrete shrinkage results in Table 1 that the silicate cement hydration product modifier prepared in the embodiment of the present invention can significantly reduce the shrinkage value of concrete at all ages, and the shrinkage rates at 1d, 7d, 14d and 28d are all lower than those in the control example, and the shrinkage reduction effect is excellent.

[0058] 3. Mechanical properties of concrete

[0059] The compressive strength test results of concrete are shown in Table 2. The dosage of the silicate cement hydration product modifier prepared by the present invention is fixed at 0.5% of the amount of cementitious material. The comparative example used is concrete without adding the silicate cement hydration product modifier, and the other components remain unchanged.

[0060] Table 2 Experimental results of concrete mechanical properties

[0061]

[0062] It can be seen from Table 2 that the Portland cement hydration product modifier prepared in the embodiment of the present invention can be added to concrete to effectively improve the 7d and 28d compressive strengths of concrete, which are higher than the experimental results of the comparative example, showing excellent mechanical properties.

Claims

1. Preparation method of silicate cement hydration product modifier, It is characterized in that The steps include: (1) Preparation of polyphenol dimer: prepare a polyphenol compound into an aqueous solution with a mass fraction of 10-20%, adjust the solution pH to 8-14, heat to 40-80° C., continuously introduce oxygen, add a catalyst, stir at a constant temperature for 6-12 hours, cool to room temperature, and filter to obtain a polyphenol dimer solution; (2) Michael addition: add the polyphenol dimer solution obtained in step (1) into a reactor, adjust the solution pH to 8-14, stir and heat to 30-50° C., continuously introduce oxygen, and under stirring conditions, dropwise add a polyamine aqueous solution with a mass fraction of 8-12% into the reactor within 4-8 hours, stir and react at a constant temperature for 1-3 hours, and cool to room temperature after the reaction to obtain a Michael addition product; (3) Grafting reaction: add the Michael addition obtained in step (2) to a reactor, adjust the pH value of the solution to 8-10, continuously introduce oxygen at room temperature, and dropwise add a 10-20% aminosilane aqueous solution into the reactor under stirring for 4-6 hours, stir and react at a constant temperature for 1-3 hours, and adjust the pH value of the solution to 4-7 after the reaction to obtain a grafted product solution; (4) Preparation of modified polysaccharide compounds: Add polysaccharide compounds, thionyl chloride and catalyst into a reactor, stir and heat to 50-70° C., continuously introduce nitrogen, react for 9-12 hours, distill under reduced pressure and dry to obtain modified polysaccharide compounds; (5) Acylation reaction: adding the grafted product solution obtained in step (3), a catalyst and a solvent into a reactor, continuously introducing nitrogen at room temperature, and dripping a 5-10% by mass aqueous solution of the modified polysaccharide compound obtained in step (4) into the reactor under stirring for 8-14 hours, stirring and reacting at a constant temperature for 1-3 hours, and distilling under reduced pressure after the reaction is completed, washing, and vacuum drying at 100-140° C. to obtain a silicate cement hydration product modifier; Wherein, the polyphenol compound in step (1) is tannic acid or baicalein; the catalyst in step (1) is manganese dioxide, potassium ferrate or potassium ferrocyanate, and the mass ratio of the catalyst to the polyphenol compound in step (1) is 0.05-0.1:1; The solute of the polyamine aqueous solution in step (2) is urea, ethylenediamine or propylenediamine, and the molar ratio of the polyamine aqueous solution to the polyphenol compound in step (1) is 0.4-0.6:1; The solute of the aminosilane aqueous solution in step (3) is γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane or N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, and the molar ratio of the solute of the polyamine aqueous solution in step (2) is 1-1.2:1; The polysaccharide compound in step (4) is hyaluronic acid or acetylated hyaluronic acid, and the molar ratio of the polysaccharide compound in step (1) is 0.4-0.6:1; the molar ratio of the thionyl chloride to the polysaccharide compound is 2-4:1; the catalyst in step (4) is N,N-dimethylformamide or pyridine, and the mass ratio of the catalyst to the polysaccharide compound is 0.01-0.05:1; The catalyst in step (5) is N,N-dimethylformamide or pyridine, and the mass ratio of its usage to the solute in the grafted product solution in step (3) is 0.05-0.1:1; the solvent in step (5) is tetrahydrofuran or dimethylacetamide, and the mass ratio of its usage to the solute in the grafted product solution in step (3) is 2.5-5:1; the molar ratio of the solute usage of the modified polysaccharide compound aqueous solution obtained in step (4) in step (5) to the solute in the polyamine aqueous solution in step (2) is 0.8-1:

1.

2. The method according to claim 1, It is characterized in that The molecular structural formula of the silicate cement hydration product modifier described in step (5) is as follows: Where R 1 for R 2 is carbonyl, ethyl or propyl; R 3 is propyl or propylaminoethyl; R 4 is hydrogen or acetyl; Wherein m and n are positive integers, representing the number of repeating units of each part in the polymer, m ranges from 5-10, and n ranges from 500-2000.

3. Application of the silicate cement hydration product modifier according to claim 1 in concrete.

Images