A concrete admixture with both anti-permeability and anti-cracking functions and a preparation method thereof

Abstract

This invention discloses a concrete admixture with both impermeability and crack prevention functions, and its preparation method, belonging to the technical field of concrete admixtures. The technical solution of this invention includes the following raw materials in parts by weight: 30-80 parts by weight of complexing agent, 3-30 parts by weight of surfactant, 7-50 parts by weight of dispersant, and 5-15 parts by weight of stabilizer. The admixture prepared by this invention synergistically couples free calcium ions, magnesium ions, metal ions, and silicates within the concrete to form a composite cross-linked network structure, preventing water molecule penetration; the reduced content of metal ions significantly reduces the shrinkage cracking effect of concrete, improving the chemical durability and stability of concrete.

Description

Technical Field

[0001] This invention relates to a concrete admixture with both impermeability and crack prevention functions, and its preparation method, specifically belonging to the field of concrete admixture technology. Background Technology

[0002] In the field of construction engineering, concrete, as the core structural material, directly affects the safety, durability, and economy of the entire project. However, as modern buildings develop towards greater height, size, and complexity, concrete faces increasingly severe environmental challenges. Especially in extreme environments such as heavy rainfall, earthquakes, and high salt spray, cracking and leakage problems in concrete structures are particularly prominent. Cracks not only weaken the overall stability of the structure but also easily become channels for the penetration of harmful substances such as moisture and salt, accelerating the deterioration process of the concrete. Leakage, on the other hand, directly threatens the building's functionality and occupant safety, and in severe cases, can even lead to structural failure.

[0003] To address these issues, scholars and engineers both domestically and internationally have developed various concrete admixtures aimed at improving the crack resistance and impermeability of concrete. One polymer-based concrete crack-resistant and waterproofing agent effectively prevents the intrusion of moisture and other harmful substances by forming a dense waterproof layer, while simultaneously enhancing the crack resistance of the concrete. However, this admixture suffers from poor compatibility with the concrete substrate and affects the workability of the concrete in practical applications. Furthermore, an inorganic nanomaterial-based concrete crack-resistant and impermeable reinforcing agent significantly improves the density and impermeability of concrete through the filling and interface effects of nanomaterials. However, this method has limitations such as high cost and complex preparation processes, and its improvement on the mechanical properties of concrete is limited.

[0004] It is worth noting that most existing concrete crack-resistant and seepage-resistant admixtures focus on improving a single performance characteristic, neglecting the fact that concrete is a complex multiphase system, and its performance improvement requires comprehensive consideration of multiple factors. Furthermore, with increasing environmental awareness, the environmental friendliness and sustainability of admixtures have become unavoidable issues. Therefore, developing a new type of concrete admixture that possesses excellent crack-resistant and seepage-resistant properties while maintaining good workability and mechanical properties of concrete, and simultaneously meeting environmental requirements, is particularly important. This admixture should significantly improve the durability and service life of concrete, reduce maintenance costs caused by cracks and leaks, and provide a more reliable, economical, and environmentally friendly solution for modern construction projects. Summary of the Invention

[0005] This invention provides a concrete admixture with both anti-seepage and anti-cracking functions and its preparation method. Through the synergistic coupling effect of various admixture chemical components, it significantly improves the durability and service life of concrete, maintains good workability and mechanical properties of concrete, and reduces maintenance costs caused by cracks and leakage, providing a more reliable, economical and environmentally friendly solution for modern construction engineering.

[0006] The present invention provides a concrete admixture that combines impermeability and crack prevention functions, which is achieved through the following implementation scheme:

[0007] The raw materials include the following parts by weight: 30-80 parts by weight of substance A, 3-30 parts by weight of surfactant, 7-50 parts by weight of dispersant and 5-15 parts by weight of stabilizer; wherein substance A is one or more of methyl ketone oxime, dimethyl ketone oxime and acetaldehyde oxime.

[0008] As a configuration of the present invention, the surfactant is one or more of sodium secondary alkyl sulfonate, sodium alkylbenzene sulfonate, and triethanolamine alkylbenzene sulfonate.

[0009] As a configuration of the present invention, the dispersant is one or more of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, and trisodium phosphate.

[0010] As a configuration of the present invention, the stabilizer is one or more of methylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose.

[0011] This invention also claims a method for preparing a concrete admixture that combines impermeability and crack prevention functions, comprising the following steps:

[0012] (1) Place complex A and surfactant into a container and stir until homogeneous to obtain mixture A;

[0013] (2) Add the dispersant and stabilizer to mixture A, stir, and heat at a constant temperature; continue stirring, and after stirring, let stand at room temperature to obtain a concrete admixture with both impermeability and crack prevention functions.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] (1) This invention reduces the slump loss of concrete over time by synergistically coupling substance A with the surfactant, dispersant and stabilizer to free calcium ions, magnesium ions, metal ions and silicates inside the concrete. It has a certain auxiliary water reduction effect and is suitable for various types of concrete that reduce the mother liquor, increase the compressive strength of concrete, reduce the seepage height and significantly reduce the cracking degree of concrete.

[0016] (2) The present invention adds the concrete admixture with anti-seepage and anti-cracking functions to the concrete. The admixture contains substances A, surfactants, dispersants and stabilizers that react synergistically with the concrete. The reduction of metal ion content can significantly reduce the shrinkage cracking effect of the concrete, improve the chemical durability and stability of the concrete, effectively prevent the penetration of water, salt and other harmful substances, and extend the service life of the concrete structure.

[0017] (3) The concrete admixture described in this invention, which combines impermeability and crack prevention, can improve the microstructure of concrete and effectively resist the formation of cracks caused by factors such as temperature changes and loads. It is suitable for complex structures such as large-span, high-rise buildings and bridges, reducing the decline in structural strength and durability caused by cracks.

[0018] (4) The present invention uses environmentally friendly raw materials, which are widely available, cheap and easy to obtain. The production process reduces the emission of harmful substances and is suitable for building projects that require high impermeability, such as basements, reservoirs and tunnels. It reduces maintenance costs and safety hazards caused by leakage and meets the requirements of green building and sustainable development. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this application can be purchased commercially or prepared by existing methods.

[0020] Example 1

[0021] A method for preparing a concrete admixture with both impermeability and crack prevention functions includes the following steps:

[0022] (1) Weigh 50 parts of methyl ethyl ketone oxime and 10 parts of sodium secondary alkyl sulfonate and put them into a container. Stir with a mixer at 3000 r / min for 30 min to obtain mixture A.

[0023] (2) Weigh 20 parts of sodium hexametaphosphate and 8 parts of methylcellulose and add them to mixture A. Stir the mixture for 120 minutes at 1000 r / min using a mixer. Then place it in a 50℃ constant temperature drying oven for 18 hours. After the heat preservation is completed, continue to stir the mixture at 500 r / min for 40 minutes and let it stand at room temperature for 4 hours to obtain a concrete admixture with both impermeability and crack prevention functions.

[0024] Example 2

[0025] A concrete admixture that combines impermeability and crack prevention functions is prepared by the following steps:

[0026] (1) Weigh 70 parts of dimethyl ketoxime and 23 parts of sodium alkylbenzene sulfonate and put them into a container. Stir with a mixer at 3500 r / min for 50 min to obtain mixture A.

[0027] (2) Weigh 37 parts of sodium tripolyphosphate and 12 parts of hydroxyethyl cellulose and add them to mixture A. Stir the mixture at 1200 r / min for 160 min using a mixer. Then place it in a 55℃ constant temperature drying oven for 20 h. After the heat preservation is completed, continue to stir the mixture at 800 r / min for 50 min using a mixer and let it stand at room temperature for 5 h to obtain a concrete admixture with both impermeability and crack prevention functions.

[0028] Example 3

[0029] A concrete admixture that combines impermeability and crack prevention functions is prepared by the following steps:

[0030] (1) Weigh 40 parts of acetaldehyde oxime and 8 parts of alkylbenzene sulfonic acid triethanolamine and put them into a container. Stir with a mixer at 2200 r / min for 30 min to obtain mixture A.

[0031] (2) Weigh 15 parts of sodium pyrophosphate and 7 parts of hydroxypropyl methylcellulose and add them to mixture A. Stir the mixture at 900 r / min for 80 min using a mixer. Then place it in a 45℃ constant temperature drying oven for 14 h. After the heat preservation is completed, continue to stir the mixture at 400 r / min for 40 min using a mixer and let it stand at room temperature for 3 h to obtain a concrete admixture with both impermeability and crack prevention functions.

[0032] Example 4

[0033] A concrete admixture that combines impermeability and crack prevention functions is prepared by the following steps:

[0034] (1) Weigh 60 parts of methyl ethyl ketone oxime and 18 parts of alkylbenzene sulfonic acid triethanolamine and put them into a container. Stir with a mixer at 3000 r / min for 40 min to obtain mixture A.

[0035] (2) Weigh 32 parts of trisodium phosphate and 10 parts of hydroxyethyl cellulose and add them to mixture A. Stir the mixture for 100 minutes at 1200 r / min using a mixer. Then place it in a 50℃ constant temperature drying oven for 16 hours. After the heat preservation is completed, continue to stir the mixture at 600 r / min for 45 minutes using a mixer. Then let it stand at room temperature for 3 hours to obtain a concrete admixture with both impermeability and crack prevention functions.

[0036] Example 5

[0037] A concrete admixture that combines impermeability and crack prevention functions is prepared by the following steps:

[0038] (1) Weigh 55 parts of dimethyl ketoxime and 17 parts of sodium secondary alkyl sulfonate and put them into a container. Stir with a mixer at 3000 r / min for 40 min to obtain mixture A.

[0039] (2) Weigh 29 parts of sodium tripolyphosphate and 10 parts of hydroxypropyl methylcellulose and add them to mixture A. Stir the mixture for 110 minutes at 1100 r / min using a mixer. Then place it in a 50℃ constant temperature drying oven for 16 hours. After the heat preservation is completed, continue to stir the mixture at 600 r / min for 45 minutes using a mixer. Then let it stand at room temperature for 3 hours to obtain a concrete admixture with both impermeability and crack prevention functions.

[0040] Comparative Example 1

[0041] The comparative example of this invention is basically the same as that of Example 1, except that methyl acetone oxime is not present in this comparative example.

[0042] Comparative Example 2

[0043] The comparative example of this invention is basically the same as that of Example 1, except that sodium secondary alkyl sulfonate is not used in this comparative example.

[0044] Comparative Example 3

[0045] The comparative example of this invention is basically the same as that of Example 1, except that sodium hexametaphosphate is not used in this comparative example.

[0046] Comparative Example 4

[0047] The comparative example of this invention is basically the same as that of Example 1, except that there is no methylcellulose in this comparative example.

[0048] Comparative Example 5

[0049] The comparative example of this invention differs from Example 1 in that methyl acetone oxime is replaced with diethylenetriaminepentaacetic acid.

[0050] Experimental Example

[0051] Preparation of concrete-type specimens:

[0052] Based on current standards and specifications, using C35 grade concrete as a benchmark, standard concrete test blocks were prepared by adding the admixtures from Examples 1-5 and Comparative Examples 1-5, and standard concrete test blocks without any admixtures were also prepared. The concrete was cured under standard conditions for 28 days, and then the concrete performance was tested according to GB / T50081-2019 "Test Methods for Physical and Mechanical Properties of Concrete" and GB / T50082-2009 "Standard for Test Methods for Long-Term Performance and Durability of Ordinary Concrete". The test results are shown in Table 1.

[0053] Table 1 Concrete Performance Indicators

[0054]

[0055] As shown in Table 1, the concrete admixtures prepared using the present invention in Examples 1-5 exhibited significantly lower 24-hour water penetration heights than the concrete admixtures prepared in incomplete compositions in Comparative Examples 1-5 and the blank control group, confirming that the prepared concrete admixtures possess excellent impermeability. The average crack area per unit area was reduced by 20-30 times, indicating that the impermeable and crack-resistant admixtures of the present invention significantly reduce the shrinkage cracking effect of concrete, improve the chemical durability and stability of concrete, effectively improve the chemical durability and stability of concrete, prevent the penetration of water, salt, and other harmful substances, and extend the service life of concrete structures. The compressive strength was also significantly higher than the design value, indicating that the prepared concrete admixtures are compatible with concrete substrates and possess better compressive durability.

[0056] As can be seen from Example 1 and Comparative Examples 1-4, in the concrete admixture system with both impermeability and crack prevention functions described in this invention, when one of the following is missing: substance A, surfactant, dispersant, and stabilizer, the average crack area is significantly reduced by 15-30 times, and the compressive strength and impermeability are also significantly improved. This indicates that substance A, surfactant, dispersant, and stabilizer work synergistically to enhance the impermeability, crack prevention, and compressive strength of the concrete admixture.

[0057] Comparison of the test results of Comparative Examples 1-5 and the blank control group shows that the absence of any one of the chemical admixtures did not significantly improve the compressive strength, water permeability, and average crack area. Only when all four substances were present did the compressive strength, water permeability, and average crack area show significant improvement, with the most significant improvement being a 15-30 fold reduction in the average crack area. When substance A was replaced with diethylenetriaminepentaacetic acid, the compressive strength effect was significantly weakened, the water permeability height showed an increasing trend, and the average crack area increased by as much as 17 times. This further proves that substance A, surfactant, dispersant, and stabilizer work synergistically to enhance the impermeability, crack prevention, and compressive strength of concrete admixtures.

[0058] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. Therefore, any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A concrete admixture with both impermeability and crack prevention functions, characterized in that, The raw materials include the following parts by weight: 30-80 parts by weight of substance A, 3-30 parts by weight of surfactant, 7-50 parts by weight of dispersant and 5-15 parts by weight of stabilizer; wherein substance A is one or more of methyl ketone oxime, dimethyl ketone oxime and acetaldehyde oxime; The surfactant is one or more of sodium secondary alkyl sulfonate, sodium alkylbenzene sulfonate, and triethanolamine alkylbenzene sulfonate. The dispersant is one or more of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, and trisodium phosphate; The stabilizer is one or more of methylcellulose, hydroxyethylcellulose, and hydroxypropyl methylcellulose.

2. A method for preparing a concrete admixture with both impermeability and crack prevention functions as described in claim 1, characterized in that, Includes the following steps: (1) Put substance A and surfactant into a container and stir to obtain mixture A; (2) Add the dispersant and stabilizer to mixture A, stir evenly, heat at a constant temperature and keep warm, continue stirring, and let stand at room temperature after stirring to obtain a concrete admixture with both impermeability and crack prevention functions.

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