Anti-freezing and anti-cracking agent for ballastless track concrete as well as preparation method and application of anti-freezing and anti-cracking agent

Abstract

The invention discloses an anti-freezing and anti-cracking agent for ballastless track concrete as well as a preparation method and application of the anti-freezing and anti-cracking agent, and belongs to the technical field of concrete admixtures. The preparation method of the anti-freezing and anti-cracking agent for the ballastless track concrete comprises the following steps: modifying a polyphenol compound dimer; the preparation method comprises the following steps: carrying out a Schiff base reaction with amino acid in an aqueous solution, dissolving the obtained Schiff base reaction product, a polyester compound and a catalyst A in a solvent, stirring in a nitrogen environment to carry out an acylation reaction, and after the reaction is finished, carrying out post-treatment to obtain the anti-freezing and anti-cracking agent. The product can effectively prevent the ballastless track concrete from cracking, and has a good anti-cracking effect. Moreover, no heavy metal raw material is added in the preparation process of the anti-freezing and anti-cracking agent for the ballastless track concrete, so that the anti-freezing and anti-cracking agent is environment-friendly, and the preparation method is simple and convenient to popularize and apply.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and in particular relates to an antifreeze and anti-cracking agent for ballastless track concrete, and a preparation method and application thereof. Background Art

[0002] Cast-in-place concrete ballastless track has been widely used in high-speed railways, heavy-duty railways, and urban rail transit due to its unique advantages. Ballastless track technology is a track technology that casts the ballast bed concrete in one step. The process is characterized by simple operation, safety and practicality, precise track geometry, and rapid positioning. Ballastless track concrete antifreeze and anti-cracking agent plays a vital role in ensuring the stability and durability of the track structure. It can not only significantly improve the antifreeze performance of concrete, but also effectively prevent concrete from cracking in low temperature environments, thereby improving the durability and service life of concrete. In low temperature environments, concrete is easily destroyed by the expansion force generated by water freezing. The effective components in the antifreeze and anti-cracking agent can react with the water in the concrete to form a tiny bubble structure, effectively slowing down the pressure and stress caused by the penetration and expansion of water during the freeze-thaw cycle, thereby improving the antifreeze performance of the concrete. In addition, during the hardening process, concrete is prone to shrinkage and cracking due to factors such as temperature and humidity changes. The antifreeze and anti-cracking agent can refine the cement particles in the concrete, promote the cement hydration reaction, and make the microstructure of the concrete more compact, thereby reducing the occurrence of cracks. Antifreeze and anti-cracking agents can significantly improve the durability and service life of concrete by improving its anti-freeze properties and preventing cracks, thereby reducing the cost of maintenance and replacement.

[0003] However, there are still key problems in the concrete antifreeze and anti-cracking agents in the prior art. For example, the concrete antifreeze and anti-cracking agents are usually expensive, which increases the investment cost of the project. In addition, the use of certain antifreeze and anti-cracking agents will affect other properties of concrete, such as reducing the strength and workability of concrete or delaying the setting time of concrete. In addition, some antifreeze and anti-cracking agents contain chemicals and heavy metals, which may pollute the surrounding environment if not properly handled. With the improvement of environmental awareness, the environmental protection performance requirements of antifreeze and anti-cracking agents are also getting higher and higher.

[0004] Therefore, how to provide a concrete antifreeze and anti-cracking agent that is environmentally friendly, has good compatibility and has good antifreeze and anti-cracking agent performance is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes an antifreeze and anti-cracking agent for ballastless track concrete.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An antifreeze and anti-cracking agent for ballastless track concrete, the molecular structure is as follows:

[0008]

[0009] Wherein, the R1 is -OH or H;

[0010] The R2 is

[0011] The R3 is

[0012] The m and n are positive integers, representing the number of repeating units of each part in the polymer, and the range of m is 5-20, and the range of n is 500-2000.

[0013] A method for preparing an antifreeze and anti-cracking agent for ballastless track concrete comprises the following steps:

[0014] The polyphenol compound dimer is modified and then reacted with an amino acid in an aqueous solution for a Schiff base reaction. The obtained Schiff base reaction product, a polyester compound and a catalyst A are then dissolved in a solvent and stirred under a nitrogen environment for an acylation reaction. After the reaction is completed, the antifreeze and anti-cracking agent is obtained by post-treatment.

[0015] Beneficial effects: Gallic acid, salicylic acid, etc. are polyphenolic compounds with high water retention. They are a class of chemical substances found in plants and have antioxidant, anti-inflammatory and other biologically active properties. In the field of materials, polyphenolic compounds have attracted much attention for their ability to retain water and reduce material shrinkage. The phenolic hydroxyl groups in their structures enable them to effectively interact with water molecules to form hydrogen bonds, thereby showing good water retention, reducing drying shrinkage and cracks, and having strong crack resistance.

[0016] The molecular chain structure of polyester compounds is relatively flexible. They have long alkane chains that can absorb external stress through movement and slippage, thereby reducing crack formation. There are interactions such as hydrogen bonds and van der Waals forces between polyester molecules, which can effectively transfer stress so that the material does not crack quickly when subjected to stress, thereby improving crack resistance.

[0017] The present invention uses amino acids as antifreeze proteins to prevent the formation and growth of ice by interacting with the surface of ice crystals. The formed microcrystals can inhibit the expansion of matrix cracks. In addition, they can produce specific interactions with water molecules or ice surfaces, thereby reducing the formation temperature of ice, delaying the crystallization process of ice, and enabling them to form stable interactions with water or ice, thereby achieving the principle of antifreeze.

[0018] Preferably, the modification method of the polyphenol compound dimer comprises the following steps:

[0019] Catalyst B is added to the aqueous solution of polyphenol compounds, and the mixture is reacted for 4-8 hours under an oxygen environment at 50-70° C. to obtain a polyphenol dimer solution; the polyphenol dimer solution, thionyl chloride and catalyst C are mixed, and the mixture is reacted for 6-10 hours under nitrogen conditions, and then the mixture is distilled and dried to obtain a modified polyphenol dimer.

[0020] Preferably, the polyphenolic compound comprises gallic acid or salicylic acid; and / or

[0021] The catalyst B comprises potassium permanganate or manganese dioxide; and / or

[0022] The catalyst C comprises N,N-dimethylformamide and / or dimethyl sulfoxide.

[0023] Preferably, the mass ratio of the polyphenol compound to the catalyst B is 1:(0.04-0.08); and / or

[0024] The mass ratio of the polyphenol compound dimer to the catalyst C is 1:(0.01-0.03).

[0025] Beneficial effects: Polyphenol compounds have excellent water retention capacity, antioxidant properties and degradability. The large number of phenolic hydroxyl structures on their molecules can firmly lock the moisture in the concrete system, reduce water evaporation, show excellent water retention, and reduce the drying shrinkage of concrete materials. At the same time, they can also act as modifiers to adjust the microstructure of hydration products, thereby improving the crack resistance and performance of the concrete matrix.

[0026] Preferably, the Schiff base reaction specifically comprises the following steps:

[0027] The pH value of the aqueous solution of the modified polyphenol compound dimer is adjusted to 7-9, and then the amino acid aqueous solution is added dropwise under oxygen conditions while stirring. After the addition is completed, the stirring reaction is continued for 2-4 hours, and then the pH value is adjusted to 5-7 to obtain the Schiff base reaction product.

[0028] Preferably, the amino acid in the aqueous amino acid solution includes glutamic acid or aspartic acid.

[0029] The molar ratio of the amino acid to the modified polyphenol compound dimer is (2-3):1.

[0030] Preferably, the polyester compound comprises polybutylene succinate or polylactic acid; and / or

[0031] The catalyst A includes pyridine or dimethyl sulfoxide.

[0032] Beneficial effects: The antifreeze and anti-cracking agent of the present invention can significantly improve the toughness and fatigue resistance of cement-based materials and reduce the brittleness of cement-based materials through special structures such as polyester in macromolecules. This performance improvement can effectively resist external cyclic loads and environmental influences, thereby extending the service life of ballastless track.

[0033] Preferably, the mass ratio of the dimer of the polyester compound and the polyphenol compound is (2-4):1; and / or

[0034] The mass ratio of the catalyst A to the solvent to the polyphenol compound dimer is (0.02-0.05):(2-4):1.

[0035] Preferably, the acylation reaction is carried out at a temperature of 30-40°C and for a time of 6-12 hours.

[0036] Preferably, the post-treatment is cooling to room temperature and continuing stirring for 1-3 hours, followed by distillation, washing and vacuum drying.

[0037] The invention discloses an application of an antifreeze and anti-cracking agent for ballastless track concrete in concrete.

[0038] A ballastless track concrete comprises the above-mentioned antifreeze and anti-cracking agent for ballastless track concrete; the addition amount of the antifreeze and anti-cracking agent for ballastless track concrete is 0.8-1% of the cementitious material.

[0039] Preferably, the cementitious material is cement, more preferably ordinary Portland cement.

[0040] More preferably, the concrete comprises the following components: substance A, substance B, sand, and crushed stone;

[0041] The substance A comprises a polycarboxylate water reducer, an air entraining agent, a gelling material and water;

[0042] The content of the polycarboxylate water-reducing agent is 2-4% of the mass of the cementitious material, the content of the air-entraining agent is 0.4-0.8% of the mass of the cementitious material, and the amount of water added is 20-30% of the mass of the total cementitious material (cementitious material and other cementitious materials);

[0043] The substance B is other cementitious materials, the above-mentioned ballastless track concrete antifreeze and anti-cracking agent and water;

[0044] The other cementitious material is fly ash;

[0045] The content of the antifreeze and anti-cracking agent in the ballastless track concrete is 0.8-1% of the mass of the cementitious material, and the amount of water added is 10-15% of the mass of the total cementitious material (cementitious material and other cementitious materials).

[0046] Compared with the prior art, the present invention has the following advantages and technical effects:

[0047] The present invention provides an antifreeze and anti-cracking agent for ballastless track concrete, a preparation method and application thereof. The antifreeze and anti-cracking agent can effectively provide low-temperature operation stability of ballastless track concrete, prevent cracking of ballastless track concrete, and has good antifreeze and anti-cracking effects.

[0048] The present invention uses amino acids, polyphenol compounds and polyester as raw materials, most of which are derived from renewable resources, have a low environmental load, and are green and low-carbon materials. Compared with traditional antifreeze and anti-cracking agents (such as those containing chemical components such as chloride salts), the preparation process and application of the present invention are friendly to the ecological environment, and are helpful to achieve sustainable development and reduce carbon emissions.

[0049] The present invention introduces polyester compounds and amino acids as raw materials, and the antifreeze and anti-cracking agent prepared in the present invention has significantly better antifreeze performance than existing products in low temperature environments. Among them, the flexible chain structure of polyester compounds and the hydrogen bond forming ability and microcrystal forming ability of amino acids effectively enhance the antifreeze and anti-cracking performance of cement-based materials, and reduce the risk of cracking of ballastless track concrete in severe cold conditions.

[0050] In the field of engineering applications, polyester compounds, amino acids and natural polyphenol compounds are used as raw materials, so that the antifreeze and anti-cracking agent prepared by the present invention can reduce the use of chemical additives in production and application, and the preparation process is simple and efficient, and has the characteristics of low toxicity and high safety. At the same time, since these components have good compatibility and processability, the application range of the antifreeze and anti-cracking agent is wider and it is easy to realize industrial production. The present invention uses antifreeze proteins (amino acids) in the field of biology and building materials and polymer materials to achieve interdisciplinary cross-disciplinary, has strong innovation, can extend the service life of ballastless track concrete, significantly improve engineering quality and reduce production costs, and has huge market potential and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0052] Figure 1 The graph is a graph showing the mass loss of the ballastless track concrete obtained in Examples 1-4 and the comparative example after 100 freeze-thaw cycles;

[0053] Figure 2 The graph is a strength loss diagram of the ballastless track concrete obtained in Examples 1-4 and the comparative example after 100 freeze-thaw cycles. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The embodiment of the present invention discloses a method for preparing an antifreeze and anti-cracking agent for ballastless track concrete, comprising the following steps:

[0056] (1) Preparation of polyphenol dimer: The polyphenol compound is prepared into an aqueous solution with a mass concentration of 20-30%, the pH value of the solution is adjusted to 7-10, the temperature is adjusted to 50-70° C., stirring is continued during the reaction and oxygen is introduced, a catalyst is added, the reaction is carried out at a constant temperature for 4-8 hours, and the reaction is cooled to room temperature to obtain a polyphenol dimer solution;

[0057] (2) Preparation of modified polyphenol dimer: Add the polyphenol dimer solution obtained in step (1), thionyl chloride (SOCl2), and a catalyst into a reactor, stir continuously and introduce nitrogen protection during the reaction, react for 6-10 hours, distill, and dry to obtain a modified polyphenol dimer;

[0058] (3) Schiff base reaction: the modified polyphenol dimer obtained in step (2) is prepared into an aqueous solution with a mass concentration of 20-30%, added to a reactor, the pH value of the solution is adjusted to 7-9, and oxygen is introduced while stirring continuously at room temperature. An antifreeze amino acid aqueous solution with a mass concentration of 20-30% is added dropwise for 4-8 hours while stirring. After the addition is completed, the stirring reaction is continued for 2-4 hours. After the reaction is completed, the pH value is adjusted to 5-7 to obtain a Schiff base reaction product;

[0059] (4) Acylation reaction: the Schiff base reaction product obtained in step (3), the polyester compound, the catalyst and the solvent are added to a reactor. During the reaction, stirring is continued and nitrogen is introduced. The temperature is adjusted to 30-40° C. and the reaction is carried out at a constant temperature for 6-12 hours. After the reaction is completed, the reaction is cooled to room temperature and stirred for 1-3 hours. The reaction is then distilled, washed and dried in a vacuum at 80-100° C. to obtain an antifreeze and anti-cracking agent for ballastless track concrete.

[0060] In some preferred embodiments, the polyphenol compound in step (1) is gallic acid or salicylic acid; the catalyst in step (1) is potassium permanganate or manganese dioxide, and the mass ratio of the amount used to the polyphenol compound in step (1) is 0.04-0.08:1.

[0061] In some preferred embodiments, the mass ratio of the amount of thionyl chloride used in step (2) to the solute of the polyphenol compound dimer solution in step (1) is 2-3:1; the catalyst in step (2) is N,N-dimethylformamide and / or dimethyl sulfoxide, and the mass ratio of the amount of thionyl chloride used in step (2) to the solute of the polyphenol compound dimer solution in step (1) is 0.01-0.03:1.

[0062] In some preferred embodiments, the antifreeze amino acid in step (3) is glutamic acid or aspartic acid, and the molar ratio of the solute dosage of the aqueous solution thereof to the modified polyphenol dimer in step (2) is 2-3:1.

[0063] In some preferred embodiments, the polyester compound in step (4) is polybutylene succinate or polylactic acid, and the mass ratio of its usage to the solute of the polyphenol compound dimer solution in step (1) is 2-4:1; the catalyst in step (4) is pyridine or dimethyl sulfoxide, and the mass ratio of its usage to the solute of the polyphenol compound dimer solution in step (1) is 0.02-0.05:1; the solvent in step (4) is dichloromethane or N,N-dimethylformamide, and the mass ratio of its usage to the solute of the polyphenol compound dimer solution in step (1) is 2-4:1.

[0064] In some preferred embodiments, the molecular structure of the ballastless track concrete antifreeze and anti-cracking agent described in step (4) is as follows:

[0065]

[0066] R1 is -OH or H; R2 is R3 is

[0067] Wherein m and n are positive integers, representing the number of repeating units of each part in the polymer, m ranges from 5-20, and n ranges from 500-2000.

[0068] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0069] Unless otherwise specified, the room temperature or normal temperature in the embodiments of the present invention refers to 25±3°C.

[0070] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0071] Example 1

[0072] A method for preparing an antifreeze and anti-cracking agent for ballastless track concrete comprises the following steps:

[0073] (1) First, 170.1 g of gallic acid and 396.9 g of water were prepared into a 30% mass concentration solution and added to a reactor, and a 40% mass concentration of sodium hydroxide aqueous solution was added, the pH was adjusted to 9, and the temperature was raised to 60° C. while stirring. Oxygen was continuously introduced during the reaction, and 6.8 g of potassium permanganate was added. The reaction was stirred at a constant temperature for 4 h. After the reaction was completed, the solution was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%;

[0074] (2) adding 283.3 g of the polyphenol compound dimer solution (mass concentration of 30%) obtained in step (1), 170 g of thionyl chloride, and 1.7 g of N,N-dimethylformamide to a reactor, continuously introducing nitrogen during the reaction, stirring at a constant temperature for 8 h, distilling, and drying to obtain a modified polyphenol compound dimer;

[0075] (3) 102.3 g (0.5 mol) of the modified polyphenol compound dimer obtained in step (2) and 238.7 g of water were prepared into a solution with a mass concentration of 30% and added to a reactor, and then a sodium hydroxide aqueous solution with a mass concentration of 30% was added to adjust the pH to 8, and oxygen was continuously introduced at room temperature. A glutamic acid solution with a mass concentration of 20% prepared by 73.6 g of glutamic acid and 294.4 g of water was added dropwise to the reactor for 4 hours. After the addition was completed, the reaction was stirred at a constant temperature for 2 hours, and then a hydrochloric acid solution with a mass concentration of 2% was added to adjust the pH to 5 to obtain a Schiff base reaction product;

[0076] (4) The Schiff base reaction product obtained in step (3), 262 g of polybutylene succinate (molecular weight 40,000), 2.1 g of pyridine, and 204.6 g of dichloromethane were added to a reactor, and nitrogen was continuously introduced. The reaction was carried out at a constant temperature of 30° C. for 6 h. After the reaction was completed, the mixture was cooled to room temperature and stirred for 2 h. The mixture was then distilled, washed, and vacuum dried at 80° C. to obtain an antifreeze and anti-cracking agent for ballastless track concrete.

[0077] A method for preparing ballastless track concrete comprises the following steps:

[0078] (1) 5.9 g of polycarboxylate water reducer (commercially available), 1.4 g of air entraining agent (commercially available), and 110 g of water were added to 280 g of cement (ordinary Portland cement P·O42.5) to obtain substance A;

[0079] (2) Add 2.25 g of the ballastless track concrete antifreeze and anti-cracking agent obtained in Example 1 and 66 g of water into 160 g of fly ash to obtain substance B;

[0080] (3) Material A, material B, 870 g of sand (medium sand), and 784 g of crushed stone (320 g of 5-10 mm crushed stone, 464 g of 10-16 mm crushed stone) were mixed and stirred uniformly to obtain antifreeze and anti-cracking modified ballastless track concrete.

[0081] Example 2

[0082] A method for preparing an antifreeze and anti-cracking agent for ballastless track concrete comprises the following steps:

[0083] (1) First, 113.4 g of gallic acid and 453.6 g of water were prepared into a 20% mass concentration solution and added to a reactor, and a 40% mass concentration of sodium hydroxide aqueous solution was added, the pH was adjusted to 8, and the temperature was raised to 70° C. while stirring. Oxygen was continuously introduced during the reaction, and 9.8 g of manganese dioxide was added. The reaction was stirred at a constant temperature for 6 h. After the reaction was completed, the solution was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%;

[0084] (2) adding 283.3 g of the polyphenol compound dimer solution (mass concentration of 30%) obtained in step (1), 255 g of thionyl chloride, and 0.85 g of dimethyl sulfoxide to a reactor, continuously introducing nitrogen during the reaction, stirring at a constant temperature for 6 h, distilling, and drying to obtain a modified polyphenol compound dimer;

[0085] (3) 68.2 g (0.5 mol) of the modified polyphenol dimer obtained in step (2) and 272.8 g of water were prepared into a solution with a mass concentration of 20% and added to a reactor, and then a sodium hydroxide aqueous solution with a mass concentration of 30% was added to adjust the pH to 8, and oxygen was continuously introduced at room temperature. 73.6 g of aspartic acid and 294.4 g of water were prepared into an aspartic acid solution with a mass concentration of 20% and added dropwise to the reactor. The addition time was 6 hours. After the addition was completed, the reaction was stirred at a constant temperature for 3 hours, and then a hydrochloric acid solution with a mass concentration of 2% was added to adjust the pH to 5 to obtain a Schiff base reaction product;

[0086] (4) The Schiff base reaction product obtained in step (3), 171 g of polybutylene succinate (molecular weight 30,000), 3.4 g of pyridine, and 331.5 g of dichloromethane were added to a reactor, and nitrogen was continuously introduced. The reaction was carried out at a constant temperature of 35° C. for 12 h. After the reaction was completed, the mixture was cooled to room temperature and stirred for 1.5 h. The mixture was then distilled, washed, and vacuum dried at 100° C. to obtain an antifreeze and anti-cracking agent for ballastless track concrete.

[0087] A method for preparing ballastless track concrete comprises the following steps:

[0088] (1) 10.3 g of polycarboxylate water reducer (commercially available), 1.1 g of air entraining agent (commercially available), and 110 g of water were added to 280 g of cement (ordinary Portland cement P·O42.5) to obtain substance A;

[0089] (2) 2.4 g of the ballastless track concrete antifreeze and anti-cracking agent obtained in Example 1 and 44 g of water were added to 160 g of fly ash to obtain substance B;

[0090] (3) Material A, material B, 870 g of sand (medium sand), and 784 g of crushed stone (320 g of 5-10 mm crushed stone, 464 g of 10-16 mm crushed stone) were mixed and stirred uniformly to obtain antifreeze and anti-cracking modified ballastless track concrete.

[0091] Example 3

[0092] A method for preparing an antifreeze and anti-cracking agent for ballastless track concrete comprises the following steps:

[0093] (1) First, 141.75 g of gallic acid and 425.25 g of water were prepared into a 25% mass concentration solution and added to a reactor, and a 40% mass concentration of sodium hydroxide aqueous solution was added, and the pH was adjusted to 9. The mixture was stirred and heated to 60° C., and oxygen was continuously introduced during the reaction. 8.5 g of potassium permanganate was added, and the mixture was stirred at a constant temperature for 4 h. After the reaction was completed, the mixture was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%;

[0094] (2) adding 283.3 g of the polyphenol compound dimer solution (mass concentration of 30%) obtained in step (1), 212.5 g of thionyl chloride, and 2.1 g of N,N-dimethylformamide to a reactor, continuously introducing nitrogen during the reaction, stirring at a constant temperature for 8 h, distilling, and drying to obtain a modified polyphenol compound dimer;

[0095] (3) 102.3 g (0.5 mol) of the modified polyphenol dimer obtained in step (2) and 238.7 g of water were prepared into a solution with a mass concentration of 30% and added to a reactor, and then a sodium hydroxide aqueous solution with a mass concentration of 30% was added to adjust the pH to 8, and oxygen was continuously introduced at room temperature. A glutamic acid solution with a mass concentration of 20% prepared by 73.6 g of glutamic acid and 294.4 g of water was added dropwise to the reactor for 8 hours. After the addition was completed, the reaction was stirred at a constant temperature for 4 hours, and then a hydrochloric acid solution with a mass concentration of 2% was added to adjust the pH to 6 to obtain a Schiff base reaction product;

[0096] (4) The Schiff base reaction product obtained in step (3), 172.9 g of polybutylene succinate (molecular weight 50,000), 3.91 g of pyridine, and 267.75 g of dichloromethane were added to a reactor, and nitrogen was continuously introduced. The reaction was carried out at a constant temperature of 30° C. for 10 h. After the reaction was completed, the mixture was cooled to room temperature and stirred for 1 h. The mixture was then distilled, washed, and vacuum dried at 90° C. to obtain an antifreeze and anti-cracking agent for ballastless track concrete.

[0097] A method for preparing ballastless track concrete comprises the following steps:

[0098] (1) 11.2 g of polycarboxylate water-reducing agent (commercially available), 2.1 g of air-entraining agent (commercially available), and 132 g of water were added to 280 g of cement (ordinary Portland cement P·O42.5) to obtain substance A;

[0099] (2) 2.8 g of the ballastless track concrete antifreeze and anti-cracking agent obtained in Example 1 and 55 g of water were added to 160 g of fly ash to obtain substance B;

[0100] (3) Material A, material B, 870 g of sand (medium sand), and 784 g of crushed stone (320 g of 5-10 mm crushed stone, 464 g of 10-16 mm crushed stone) were mixed and stirred uniformly to obtain antifreeze and anti-cracking modified ballastless track concrete.

[0101] Example 4

[0102] A method for preparing an antifreeze and anti-cracking agent for ballastless track concrete comprises the following steps:

[0103] (1) First, 170.1 g of gallic acid and 396.9 g of water were prepared into a 30% mass concentration solution and added to a reactor, and a 40% mass concentration of sodium hydroxide aqueous solution was added, the pH was adjusted to 9, and the temperature was raised to 60° C. while stirring. Oxygen was continuously introduced during the reaction, and 6.8 g of potassium permanganate was added. The reaction was stirred at a constant temperature for 4 h. After the reaction was completed, the solution was cooled to room temperature to obtain a polyphenol compound dimer solution, and the mass concentration was adjusted to 30%;

[0104] (2) adding 283.3 g of the polyphenol compound dimer solution (mass concentration of 30%) obtained in step (1), 255 g of thionyl chloride, and 2.5 g of N,N-dimethylformamide to a reactor, continuously introducing nitrogen during the reaction, stirring at a constant temperature for 8 h, distilling, and drying to obtain a modified polyphenol compound dimer;

[0105] (3) 85.25 g (0.5 mol) of the modified polyphenol dimer obtained in step (2) and 255.75 g of water are prepared into a solution with a mass concentration of 25% and added to a reactor, and then a sodium hydroxide aqueous solution with a mass concentration of 30% is added to adjust the pH to 8, and oxygen is continuously introduced at room temperature. A glutamic acid solution with a mass concentration of 20% prepared by 73.6 g of glutamic acid and 294.4 g of water is added dropwise to the reactor for 5 hours. After the addition is completed, the reaction is stirred at a constant temperature for 2.5 hours, and then a hydrochloric acid solution with a mass concentration of 2% is added to adjust the pH to 7 to obtain a Schiff base reaction product;

[0106] (4) The Schiff base reaction product obtained in step (3), 328.5 g of polybutylene succinate (molecular weight 40,000), 1.8 g of pyridine, and 188.4 g of dichloromethane were added to a reactor, and nitrogen was continuously introduced. The reaction was carried out at a constant temperature of 40° C. for 8 h. After the reaction was completed, the mixture was cooled to room temperature and stirred for 3 h. The mixture was then distilled, washed, and vacuum dried at 85° C. to obtain an antifreeze and anti-cracking agent for ballastless track concrete.

[0107] A method for preparing ballastless track concrete comprises the following steps:

[0108] (1) 8.4 g of polycarboxylate water reducer (commercially available), 2.24 g of air entraining agent (commercially available), and 88 g of water were added to 280 g of cement (ordinary Portland cement P·O42.5) to obtain substance A;

[0109] (2) Add 2.6 g of the ballastless track concrete antifreeze and anti-cracking agent obtained in Example 1 and 60 g of water into 160 g of fly ash to obtain substance B;

[0110] (3) Material A, material B, 870 g of sand (medium sand), and 784 g of crushed stone (320 g of 5-10 mm crushed stone, 464 g of 10-16 mm crushed stone) were mixed and stirred uniformly to obtain antifreeze and anti-cracking modified ballastless track concrete.

[0111] Technical effect:

[0112] 1. Concrete shrinkage reduction effect:

[0113] The shrinkage test results of the concrete obtained in Examples 1-4 are shown in Table 1. The detection standard is GB / T50082. The dosage of the antifreeze and anti-cracking agent for preparing ballastless track concrete of the present invention is fixed to 0.8% of the dosage of the cementitious material (cement). The comparative example (Blank) used is concrete to which the antifreeze and anti-cracking agent for ballastless track concrete is not added, and the other components remain unchanged.

[0114] Table 1 Concrete shrinkage test results

[0115] Group Dosage% <![CDATA[7d(×10 -6 )]]> <![CDATA[28d(×10 -6 )]]> <![CDATA[60d(×10 -6 )]]> Blank 0 -18.95 -25.19 -36.22 Example 1 0.8 -12.99 -17.96 -28.40 Example 2 0.8 -13.10 -17.85 -27.23 Example 3 0.8 -13.21 -18.04 -27.48 Example 4 0.8 -13.09 -17.62 -26.11

[0116] It can be seen from the concrete shrinkage results in Table 1 that the ballastless track concrete antifreeze and anti-cracking agent prepared in the embodiment of the present invention can significantly reduce the shrinkage value of concrete at all ages, and the shrinkage reduction effect is excellent.

[0117] 2. Concrete antifreeze effect:

[0118] The antifreeze test results of the concrete obtained in Examples 1-4 are as follows: Figure 1 and Figure 2 As shown, the testing standard is GB / T 50082, the dosage of the antifreeze and anti-cracking agent for preparing ballastless track concrete of the present invention is fixed to 0.8% of the amount of cementitious material, the comparative example (Blank) used is concrete without adding the antifreeze and anti-cracking agent for ballastless track concrete, and the other components remain unchanged.

[0119] from Figure 1 It can be seen that the mass loss of the four groups of samples added with ballastless track concrete antifreeze and anti-cracking agent is lower than that of the blank group (Blank). Figure 2 It can be seen that the strength loss of the four groups of samples added with ballastless track concrete antifreeze and anti-cracking agent is lower than that of the blank group, indicating that the addition of ballastless track concrete antifreeze and anti-cracking agent plays a certain protective role on cement-based materials, reduces the impact of freeze-thaw cycles on the structure of cement-based materials, and has excellent antifreeze effect.

[0120] 3. Concrete anti-cracking effect:

[0121] The anti-cracking test results of the concrete obtained in Examples 1-4 are shown in Table 2. The detection standard is GB / T50082, and the dosage of the antifreeze and anti-cracking agent for preparing ballastless track concrete of the present invention is fixed to 0.8% of the amount of cementitious material. The comparative example used is concrete without adding the antifreeze and anti-cracking agent for ballastless track concrete, and the other components remain unchanged.

[0122] Table 2 Concrete crack resistance test results

[0123]

[0124] It can be seen from the concrete anti-cracking results in Table 2 that the cracking time of each embodiment added with the antifreeze and anti-cracking agent for preparing ballastless track concrete is greater than that of the comparative example, and the crack width and crack area of ​​each embodiment added with the antifreeze and anti-cracking agent for preparing ballastless track concrete are smaller than that of the comparative example, and the anti-cracking effect is significantly improved.

[0125] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An antifreeze and anti-cracking agent for ballastless track concrete, characterized in that: The molecular structure is shown below: Wherein, the R1 is -OH or H; The R2 is The R3 is The m and n are positive integers, representing the number of repeating units of each part in the polymer, and the range of m is 5-20, and the range of n is 500-2000.

2. The method for preparing an antifreeze and anti-cracking agent for ballastless track concrete according to claim 1, characterized in that: The following steps are involved: The polyphenol compound dimer is modified and then reacted with an amino acid in an aqueous solution for a Schiff base reaction. The obtained Schiff base reaction product, a polyester compound and a catalyst A are then dissolved in a solvent and stirred under a nitrogen environment for an acylation reaction. After the reaction is completed, the antifreeze and anti-cracking agent is obtained by post-treatment.

3. The method for preparing an antifreeze and anti-cracking agent for ballastless track concrete according to claim 2, characterized in that: The modification method of the polyphenol compound dimer comprises the following steps: Catalyst B is added to the aqueous solution of polyphenol compounds, and the mixture is reacted for 4-8 hours under an oxygen environment at 50-70° C. to obtain a polyphenol dimer solution; the polyphenol dimer solution, thionyl chloride and catalyst C are mixed, and the mixture is reacted for 6-10 hours under nitrogen conditions, and then the mixture is distilled and dried to obtain a modified polyphenol dimer.

4. The method for preparing an antifreeze and anti-cracking agent for ballastless track concrete according to claim 3, characterized in that: The polyphenolic compound comprises gallic acid or salicylic acid; and / or The catalyst B comprises potassium permanganate or manganese dioxide; and / or The catalyst C comprises N,N-dimethylformamide and / or dimethyl sulfoxide.

5. The method for preparing an antifreeze and anti-cracking agent for ballastless track concrete according to claim 1, characterized in that: The Schiff base reaction specifically comprises the following steps: The pH value of the aqueous solution of the modified polyphenol compound dimer is adjusted to 7-9, and then the amino acid aqueous solution is added dropwise under oxygen conditions while stirring. After the addition is completed, the stirring reaction is continued for 2-4 hours, and then the pH value is adjusted to 5-7 to obtain the Schiff base reaction product.

6. The method for preparing an antifreeze and anti-cracking agent for ballastless track concrete according to claim 5, characterized in that: The amino acid in the amino acid aqueous solution includes glutamic acid or aspartic acid.

7. The method for preparing an antifreeze and anti-cracking agent for ballastless track concrete according to claim 1, characterized in that: The polyester compound includes polybutylene succinate or polylactic acid; and / or The catalyst A includes pyridine or dimethyl sulfoxide.

8. Use of the antifreeze and anti-cracking agent for ballastless track concrete as claimed in claim 1 in concrete.

9. A ballastless track concrete, characterized in that: The invention comprises the antifreeze and anti-cracking agent for ballastless track concrete as claimed in claim 1; the addition amount of the antifreeze and anti-cracking agent for ballastless track concrete is 0.8-1% of the cementitious material.

10. The ballastless track concrete according to claim 9, characterized in that: The gelling material is cement.

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