Temperature response type flowable concrete admixture as well as preparation method and application thereof

Abstract

The invention relates to a temperature-responsive flowable concrete admixture which comprises the following raw materials in percentage by mass: 30-50% of a temperature-sensitive polymer material, 2-5% of a cross-linking agent, 3-5% of a water-soluble water reducing agent, 1-3% of a plasticizer and 40-60% of water, wherein the temperature-sensitive high polymer material is selected from one or more of polyvinyl alcohol and sodium polyacrylate. The temperature response type flowable concrete admixture disclosed by the invention can be applied to concrete to realize dynamic adjustment under temperature change, so that the excellent construction performance of the concrete under different environmental conditions is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a temperature-responsive fluid concrete admixture and a preparation method and application thereof. Background Art

[0002] In the field of construction engineering, concrete is a widely used basic material, and its performance plays a decisive role in the quality and construction efficiency of the project. Among them, the fluidity of concrete is a key performance indicator, which is directly related to each construction link such as concrete mixing, transportation, pouring and molding. However, in actual application scenarios, the fluidity of traditional concrete is significantly affected by the ambient temperature.

[0003] In high temperature environments, such as during construction in hot summer, the evaporation rate of water inside the concrete is greatly accelerated, and the cement hydration reaction rate is also significantly increased. This series of changes leads to excessive fluidity of the concrete, which exceeds the range suitable for construction. At this time, the concrete is prone to bleeding during the pouring process, that is, the cement paste separates from the aggregate and the water floats to the surface of the concrete. This bleeding phenomenon not only causes a floating slurry layer on the surface of the concrete, reducing the strength and durability of the concrete, but also causes an uneven internal structure of the concrete, increasing the risk of cracks. At the same time, excessive fluidity may also make the stability of the concrete in the formwork worse, prone to deformation, collapse and other construction difficulties, seriously affecting the quality and progress of construction. On the contrary, in low temperature environments, especially during construction in cold winter, the hydration reaction of the concrete becomes slow, and the interaction between cement particles and water is inhibited. This directly causes a serious lack of fluidity of the concrete, which is manifested as the concrete is too viscous and difficult to flow and fill smoothly in the formwork. When pouring concrete under such circumstances, it is difficult to distribute the concrete evenly in every corner of the formwork, and defects such as pores and honeycombs are easily formed, which greatly reduces the density and strength of the concrete and poses a serious threat to the safety and durability of the concrete structure.

[0004] In order to overcome these shortcomings of traditional concrete in terms of fluidity, adding fluidity admixtures to concrete has become a common solution. Existing fluidity admixtures can improve the initial fluidity of concrete and improve its working performance to a certain extent. However, these traditional admixtures have a significant limitation, that is, they do not fully consider the fluctuation of ambient temperature and the resulting dynamic impact on the fluidity of concrete. This leads to unstable construction performance of concrete in the actual construction process, and it is difficult to adapt to the temperature changes in different seasons, different time periods and different regions, thus bringing many inconveniences and quality risks to the construction of construction projects. Summary of the invention

[0005] In order to solve the above-mentioned problems of the prior art, the present invention provides a temperature-responsive fluid concrete admixture, which introduces a specific temperature-sensitive polymer material, combines an appropriate amount of a cross-linking agent, a plasticizer, a water reducer and water, and is applied to concrete to automatically adjust the fluidity of the concrete according to changes in ambient temperature, thereby achieving dynamic adjustment under temperature changes, and thus ensuring the excellent construction performance of the concrete under different environmental conditions.

[0006] The present invention provides the following technical solutions.

[0007] A temperature-responsive fluid concrete admixture, comprising the following raw materials, measured by mass percentage: 30% to 50% of a temperature-sensitive polymer material, 2% to 5% of a cross-linking agent, 3% to 5% of a water-soluble water-reducing agent, 1% to 3% of a plasticizer, and 40% to 60% of water;

[0008] Wherein, the temperature sensitive polymer material is selected from one or more of polyvinyl alcohol and sodium polyacrylate.

[0009] In the present invention, temperature-sensitive polymer materials are the key parts of temperature-responsive fluid concrete admixtures, which are selected from one or more of polyvinyl alcohol (PVA) and sodium polyacrylate. Polyvinyl alcohol and sodium polyacrylate can interact with water molecules to varying degrees at different temperatures by virtue of their molecular characteristics, thereby achieving temperature-responsive regulation of concrete fluidity. At the same time, the cross-linking agent reacts with the active groups of polyvinyl alcohol or sodium polyacrylate to construct a stable cross-linking network, enhance the temperature resistance and stability of the polymer material, and resist the adverse effects of temperature changes. Water-soluble water reducers use steric hindrance and electrostatic repulsion to disperse cement particles, reduce water consumption to improve fluidity. Plasticizers reduce the forces between the molecular chains of polymer materials, enhance the mobility and flexibility of the molecular chains, optimize the plasticity and workability of concrete, and jointly ensure that concrete has good working performance and quality performance under different temperature environments.

[0010] In the temperature-responsive fluid concrete admixture of the present invention, the control of the amount of each component is crucial. If the amount of temperature-sensitive polymer material is too small, the fluidity cannot be effectively adjusted, and if it is too large, the homogeneity and fluidity balance of the system will be destroyed and the strength will be affected. Insufficient amount of cross-linking agent makes it difficult to form a stable cross-linked structure, which affects the temperature resistance and long-term effectiveness, and excessive amount makes the material rigid and poor in flexibility. Too little water-soluble water-reducing agent will result in poor dispersion and water-reducing effects, and too much will cause concrete segregation. Too little plasticizer is difficult to improve plasticity and workability, and too much will reduce mechanical properties. Therefore, only by strictly limiting the amount of each component as described above can synergistic synergy be achieved, the optimal comprehensive performance can be exerted, and the precise regulation of the fluidity of concrete at different temperatures, as well as the engineering quality and construction convenience can be guaranteed.

[0011] In a preferred embodiment, the temperature-responsive fluid concrete admixture includes the following raw materials, measured in mass percentage: 34% to 46% temperature-sensitive polymer material, 3% to 5% cross-linking agent, 3% to 5% water-soluble water reducer, 2% to 3% plasticizer, and 44% to 55% water.

[0012] In one embodiment, the temperature-responsive fluid concrete admixture includes the following raw materials, measured in mass percentage: 40% temperature-sensitive polymer material, 3% cross-linking agent, 4% water-soluble water reducer, 2% plasticizer, and 51% water.

[0013] In one embodiment, the temperature-responsive fluid concrete admixture includes the following raw materials, measured in mass percentage: 46% temperature-sensitive polymer material, 5% cross-linking agent, 3% water-soluble water reducer, 2% plasticizer, and 44% water.

[0014] In one embodiment, the temperature-responsive fluid concrete admixture includes the following raw materials, measured in percentage by mass: 34% temperature-sensitive polymer material, 3% cross-linking agent, 5% water-soluble water reducer, 3% plasticizer, and 55% water.

[0015] In one embodiment, the temperature sensitive polymer material is a mixture of polyvinyl alcohol and sodium polyacrylate.

[0016] In the temperature-responsive fluid concrete admixture of the present invention, a mixture of polyvinyl alcohol and sodium polyacrylate is used as a temperature-sensitive polymer material, which combines the advantages of both materials and synergizes them. It can accurately adjust the internal structure and interaction of concrete according to temperature changes, thereby enhancing construction adaptability and quality reliability.

[0017] In one embodiment, the mass ratio of the polyvinyl alcohol to the sodium polyacrylate is (1.5-2):1.

[0018] It can be understood that in the present invention, the mass ratio of the polyvinyl alcohol to the sodium polyacrylate includes but is not limited to 1.5:1, 1.56:1, 1.6:1, 1.67:1, 1.7:1, 1.8:1, 1.83:1, 1.9:1, and 2:1.

[0019] In one embodiment, the cross-linking agent is selected from one or more of N,N'-methylenebisacrylamide, 1,4-benzenediacrylamide and N,N'-bis(acryloyl)cystamine.

[0020] In a preferred embodiment, the cross-linking agent is N,N'-methylenebisacrylamide.

[0021] In the temperature-responsive fluid concrete admixture of the present invention, N,N'-methylenebisacrylamide can construct a stable cross-linked network, enhance the polymer mechanics and stability, and cooperate with other components in the formula to achieve the purpose of adaptively adjusting the cross-linked network structure to temperature changes, effectively regulate the fluidity of concrete, and ensure the quality and performance of the structure.

[0022] In one embodiment, the water-soluble water reducing agent is a polycarboxylate water reducing agent.

[0023] The addition of water-soluble water reducers can effectively reduce the adsorption and friction resistance between cement particles in concrete, and promote the uniform dispersion of cement particles in the system. Among them, polycarboxylate water reducers have good adaptability compared to other water-soluble water reducers, are not easily affected by fluctuations in cement composition, and ensure that concrete can maintain good working performance under different temperature environments.

[0024] In one embodiment, the polycarboxylate water reducer is selected from one or more of TPEG water reducer, HPEG water reducer and APEG water reducer.

[0025] In one embodiment, the plasticizer is selected from one or more of glycerol and polyvinyl alcohol ether.

[0026] The present invention selects one or more of glycerol and polyvinyl alcohol ether as plasticizers, which can be effectively inserted into temperature-sensitive polymer materials and other polymer chains in the concrete system, making the concrete easier to deform and flow in the plastic stage. At the same time, glycerol and / or polyvinyl alcohol ether can also cooperate with temperature-sensitive polymer materials to improve the adaptability of concrete to temperature changes to a certain extent.

[0027] The present invention also provides a method for preparing the temperature-responsive fluid concrete admixture as described above, comprising the following steps:

[0028] Mixing the temperature-sensitive polymer material with water to dissolve the temperature-sensitive polymer material and prepare a first solution;

[0029] adding the cross-linking agent to the first solution to prepare a second solution;

[0030] The water-soluble water reducing agent and the plasticizer are added to the second solution to prepare the temperature-responsive fluid concrete admixture.

[0031] In one embodiment, the temperature for mixing the temperature-sensitive polymer material and water is room temperature.

[0032] In one embodiment, the cross-linking agent is added while stirring.

[0033] In one embodiment, the preparation method of the temperature-responsive fluid concrete admixture comprises the following steps:

[0034] Material preparation: preparing the temperature-sensitive polymer material, the cross-linking agent, the water-soluble water-reducing agent, the plasticizer and water according to the mass percentages as described above, ensuring that the quality and particle size of the temperature-sensitive polymer material meet industry requirements;

[0035] Dissolving and mixing: Mix the temperature-sensitive polymer material with water and stir until completely dissolved. The dissolving temperature of the temperature-sensitive polymer material is controlled at room temperature to avoid excessively high temperature causing changes in the performance of the polymer material. After the dissolution is complete, add the cross-linking agent. The cross-linking agent needs to be added gradually during the stirring process and stirred sufficiently to avoid agglomeration. Then add the water-soluble water reducer and plasticizer in sequence and continue stirring until they are evenly distributed.

[0036] Preparation of admixture solution: Continue stirring the above dissolved mixed solution until it is completely uniform to form a stable admixture solution. The stable admixture solution is transparent or translucent and has no obvious precipitation;

[0037] Cooling and storage: The prepared admixture solution is naturally cooled to room temperature. During the cooling process, avoid exposure to direct sunlight or excessively high temperatures to avoid affecting the temperature response performance of the admixture. When storing the admixture solution, store it in a sealed container to prevent moisture and impurities in the air from affecting its quality.

[0038] The present invention also provides the use of the temperature-responsive fluid concrete admixture described above in preparing concrete.

[0039] The beneficial effects of the present invention are embodied in that:

[0040] By selecting one or more of polyvinyl alcohol and sodium polyacrylate as temperature-sensitive polymer materials, combined with a specific mass ratio of cross-linking agent, plasticizer, water-soluble water reducer and water, an admixture system that can sensitively sense changes in ambient temperature was constructed. When the ambient temperature changes, the physicochemical properties of the temperature-sensitive polymer material will change accordingly, specifically changing the polymerization and shrinkage characteristics of the molecular structure, thereby driving the entire admixture system to dynamically adjust the interaction between the admixture and the various components of concrete, thereby automatically adjusting the fluidity of the concrete.

[0041] Furthermore, the temperature-responsive fluidity admixture and the preparation method thereof provided by the present invention are particularly suitable for self-compacting concrete (SCC). Whether it is reducing the fluidity of concrete by shrinking the molecular chains in a high temperature environment, thereby preventing excessive increase in fluidity and avoiding bleeding, or increasing the fluidity of concrete by expanding the molecular chains in a low temperature environment, thereby improving the fluidity to ensure smooth pouring, the admixture of the present invention can achieve precise temperature response and dynamic adjustment, effectively ensuring that the concrete always has excellent construction performance under different environmental conditions, ensuring that the concrete always has ideal construction performance under different temperature conditions, and avoiding the influence of temperature fluctuations on the construction quality of concrete. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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.

[0043] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available products.

[0044] Embodiment 1:

[0045] A temperature-responsive fluidity admixture that can be used at room temperature (25°C) is prepared from raw materials containing the following mass percentages: 40% of temperature-sensitive polymer material (25% of polyvinyl alcohol and 15% of sodium polyacrylate), 3% of a cross-linking agent (N,N'-methylenebisacrylamide), 4% of a water-soluble water reducer (TPEG-type water reducer), 2% of a plasticizer (glycerol), and 51% of water.

[0046] Preparation method: Mix the above-mentioned temperature-sensitive polymer material with water at room temperature, stir until completely dissolved, add the cross-linking agent after complete dissolution, and add the cross-linking agent gradually during the stirring process, and stir well to avoid caking, then add the water-soluble water reducer and plasticizer in turn, continue stirring until completely uniform, and form a stable admixture solution, which is transparent or translucent and has no obvious precipitation.

[0047] Embodiment 2:

[0048] A temperature-responsive fluidity admixture that can be used in a high temperature environment (above 30°C) is prepared from raw materials containing the following mass percentages: 46% of a temperature-sensitive polymer material (28% of polyvinyl alcohol and 18% of sodium polyacrylate), 5% of a cross-linking agent (N,N'-methylenebisacrylamide), 3% of a water-soluble water reducer (TPEG-type water reducer), 2% of a plasticizer (glycerol), and 44% of water.

[0049] The preparation method is consistent with that in Example 1.

[0050] Embodiment 3:

[0051] A temperature-responsive fluidity admixture that can be used in a low-temperature environment (below 5°C) is prepared from raw materials containing the following mass percentages: 34% of a temperature-sensitive polymer material (22% of polyvinyl alcohol and 12% of sodium polyacrylate), 3% of a cross-linking agent (N,N'-methylenebisacrylamide), 5% of a water-soluble water reducer (TPEG-type water reducer), 3% of a plasticizer (glycerol), and 55% of water.

[0052] The preparation method is consistent with that in Example 1.

[0053] Embodiment 4:

[0054] Other conditions were the same as those in Example 1, except for the raw material: 40% of temperature-sensitive polymer material (40% of polyvinyl alcohol).

[0055] Embodiment 5:

[0056] Other conditions were the same as those in Example 2, with only the raw material changed: 46% of temperature-sensitive polymer material (46% of sodium polyacrylate).

[0057] Embodiment 6:

[0058] Other conditions were the same as those in Example 3, except for the raw materials: 34% of temperature-sensitive polymer material (12% of polyvinyl alcohol and 22% of sodium polyacrylate).

[0059] Comparative Example 1:

[0060] An admixture, other conditions are consistent with Example 1, only the mass fraction of raw materials is changed: temperature-sensitive polymer material 25% (polyvinyl alcohol 16%, sodium polyacrylate 9%), cross-linking agent (N,N'-methylenebisacrylamide) 3%, water-soluble water reducer (TPEG type water reducer) 4%, plasticizer (glycerol) 2%, and water 66%.

[0061] Comparative Example 2:

[0062] An additive, other conditions are consistent with Example 2, only the raw material is changed: 46% of temperature sensitive polymer material (46% of polyisopropylacrylamide).

[0063] Comparative Example 3:

[0064] An admixture, other conditions are consistent with Example 3, only the mass fraction of raw materials is changed: temperature-sensitive polymer material 55% (polyvinyl alcohol 35%, sodium polyacrylate 20%), cross-linking agent (N,N'-methylenebisacrylamide) 3%, water-soluble water reducer (TPEG type water reducer) 5%, plasticizer (glycerol) 3%, and water 34%.

[0065] Performance Testing

[0066] The same mass of admixtures prepared in Examples 1-6 and Comparative Examples 1-3 were mixed with cement, sand and stone respectively, and concrete test blocks were prepared by the same method to conduct performance tests.

[0067] The performance test results are shown in Table 1.

[0068] Table 1

[0069]

[0070] In the description of the embodiments of the present invention, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0071] In the description of the embodiments of the present invention, it is to be understood that "-" and "~" represent the range between two values, and the range includes the endpoints. For example: "AB" represents a range greater than or equal to A and less than or equal to B. "A~B" represents a range greater than or equal to A and less than or equal to B.

[0072] In the description of the embodiments of the present invention, the term "and / or" herein is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " herein generally indicates that the associated objects before and after are in an "or" relationship.

[0073] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A temperature-responsive fluid concrete admixture, characterized in that: The raw materials include, by mass percentage, 30% to 50% of temperature-sensitive polymer material, 2% to 5% of cross-linking agent, 3% to 5% of water-soluble water-reducing agent, 1% to 3% of plasticizer, and 40% to 60% of water; Wherein, the temperature sensitive polymer material is selected from one or more of polyvinyl alcohol and sodium polyacrylate.

2. The temperature-responsive fluid concrete admixture according to claim 1, characterized in that: The temperature-responsive fluid concrete admixture comprises the following raw materials in percentage by mass: 34% to 46% of temperature-sensitive polymer material, 3% to 5% of cross-linking agent, 3% to 5% of water-soluble water reducer, 2% to 3% of plasticizer, and 44% to 55% of water.

3. The temperature-responsive fluid concrete admixture according to claim 1 or 2, characterized in that: The temperature sensitive polymer material is a mixture of polyvinyl alcohol and sodium polyacrylate; the mass ratio of the polyvinyl alcohol to the sodium polyacrylate is (1.5-2):

1.

4. The temperature-responsive fluid concrete admixture according to claim 1 or 2, characterized in that: The cross-linking agent is selected from one or more of N,N'-methylenebisacrylamide, 1,4-benzenediacrylamide and N,N'-bis(acryloyl)cystamine.

5. The temperature-responsive fluid concrete admixture according to claim 1 or 2, characterized in that: The water-soluble water reducing agent is a polycarboxylate water reducing agent.

6. The temperature-responsive fluid concrete admixture according to claim 1 or 2, characterized in that: The plasticizer is selected from one or more of glycerol and polyvinyl alcohol ether.

7. The method for preparing the temperature-responsive fluid concrete admixture according to any one of claims 1 to 6, characterized in that: The steps include: Mixing the temperature-sensitive polymer material with water to dissolve the temperature-sensitive polymer material and prepare a first solution; adding the cross-linking agent to the first solution to prepare a second solution; The water-soluble water reducing agent and the plasticizer are added to the second solution to prepare the temperature-responsive fluid concrete admixture.

8. The method for preparing the temperature-responsive fluid concrete admixture according to claim 7, characterized in that: The temperature for mixing the temperature-sensitive polymer material and water is room temperature.

9. The method for preparing the temperature-responsive fluid concrete admixture according to claim 7, characterized in that: The cross-linking agent is added while stirring.

10. Use of the temperature-responsive fluid concrete admixture according to any one of claims 1 to 6 in preparing concrete.

Images