Early-strength quick-setting concrete based on composite cement system and preparation method of early-strength quick-setting concrete

Abstract

The invention belongs to the technical field of building materials, and particularly relates to early strength type quick-setting concrete based on a composite cement system and a preparation method thereof, the early strength type quick-setting concrete comprises 400 parts of water, 400-460 parts of cement, 700-780 parts of sand, 980-1150 parts of gravel, 25-30 parts of cellulose, 18-26 parts of polyvinyl alcohol and 30-35 parts of an accelerator; aluminum ions and sulfate ions are subjected to a polymerization reaction to form a polymer with a specific structure, and an organic high-molecular polymer is added, so that the organic high-molecular polymer interacts with an aluminum sulfate polymerization product, and the performance of the accelerator is further modified.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to an early-strength quick-setting concrete of a composite cement system and a preparation method thereof. Background Art

[0002] With the continuous development of today's society, a large number of new buildings need to be constructed, which requires a large amount of concrete. Concrete has the characteristics of high compressive strength and good durability, and is therefore widely used in civil engineering. After the various raw materials of concrete are mixed, multiple steps such as drying and curing are required to allow the concrete to solidify and thus have good compressive strength, which can play a bonding and supporting role for the building. However, this process often takes a lot of time, which delays the construction period and increases production costs. Therefore, in order to speed up the construction rate and reduce production and construction costs, the existing production process adds accelerators to the concrete to increase the setting rate of the concrete. Therefore, to address the above problems, a kind of early-strength quick-setting concrete based on a composite cement system and its preparation method are proposed. Summary of the Invention

[0003] In order to make up for the shortcomings of the existing technology and solve the problem that the concrete setting process takes a lot of time, the present invention proposes an early-strength quick-setting concrete based on a composite cement system and a preparation method thereof.

[0004] The technical solution adopted by the present invention to solve the technical problem is: the early-strength quick-setting concrete based on the composite cement system and the preparation method thereof, comprising 400 parts of water, 400-460 parts of cement, 700-780 parts of sand, 980-1150 parts of crushed stone, 25-30 parts of cellulose, 18-26 parts of polyvinyl alcohol, and 30-35 parts of accelerating agent; The quick-setting agent is composed of aluminum sulfate (Al2(SO4)3), sulfuric acid (H2SO4), aluminum hydroxide and polyacrylate in a mass ratio of (2-3): (3-5): (1-2): (4-6).

[0005] Preferably, the method for preparing the quick-setting agent comprises the following steps: S1: Dissolve aluminum sulfate in water to prepare a certain concentration of aluminum sulfate solution, generally between 20% and 40%. During the dissolution process, appropriate heating and stirring can be performed to speed up the dissolution rate. The temperature is generally controlled between 40-60°C.

[0006] S2: Slowly add sulfuric acid to the aluminum sulfate solution while stirring, adjusting the solution's pH to within a certain range, typically between 2 and 4. Then, add an appropriate amount of aluminum hydroxide and continue stirring to allow the aluminum ions in the solution to fully react with sulfate ions and other ions, forming an aluminum sulfate polymer. The reaction equation is complex, but it generally describes a polymerization reaction between aluminum ions and sulfate ions under certain conditions, forming a polymer with a specific structure.

[0007] S3: An organic polymer is then added to interact with the aluminum sulfate polymer product, further modifying the properties of the accelerator. The reaction temperature is generally controlled between 60-80°C and the reaction time is 3-8 hours. After the reaction is complete, the solution may contain unreacted solid impurities and some insoluble substances, which are removed by filtration to obtain a clear alkali-free accelerator solution.

[0008] Preferably, the quick-setting agent is composed of aluminum sulfate (Al2(SO4)3), sulfuric acid (H2SO4), aluminum hydroxide and polyacrylate in a mass ratio of 2:5:1:4.

[0009] A method for preparing early-strength rapid-setting concrete based on a composite cement system, which is applicable to any of the above-mentioned early-strength rapid-setting concrete based on a composite cement system, comprises the following steps: S1: Put the cement, sand, gravel, cellulose and polyvinyl alcohol dry materials in the above weight ratio into a mixer and mix them evenly to prepare a dry mix; S2: adding 80% by weight of the water to the dry mix prepared in step S1, mixing well and letting it stand for 30 minutes, then adding the remaining 20% ​​by weight of the water, stirring and mixing well to prepare a concrete slurry; S3: Add the accelerator in the later stage of mixing and continue stirring to ensure that the accelerator is evenly dispersed in the concrete; S4: For poured quick-setting concrete, appropriate vibration should be carried out as needed to eliminate bubbles in the concrete and improve the density of the concrete.

[0010] S5: Drying, solidifying and curing the concrete slurry prepared in step S4.

[0011] Preferably, the preparation method of the early strength quick-setting concrete comprises 400 parts of water, 150 parts of (PO42.5) cement, 270 parts of (L.SAC52.5) ​​cement, 780 parts of sand, 1150 parts of crushed stone (5-20mm), 30 parts of cellulose, 20 parts of polyvinyl alcohol, and 30 parts of accelerating agent. The benefits of the present invention are that aluminum sulfate (Al2(SO4)3) can react with gypsum in cement to form ettringite, which causes rapid setting; sulfuric acid (H2SO4) can reduce the pH value of the liquid phase and promote the hydration of C3S; aluminum hydroxide can provide an alkaline environment to accelerate the reaction; aluminum ions and sulfate ions undergo polymerization reaction to form polymers with a specific structure; and the addition of organic high molecular polymers allows them to interact with the aluminum sulfate polymerization product, further modifying the performance of the accelerating setting agent. DETAILED DESCRIPTION

[0012] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0013] Example 1 Disclosed are an early-strength quick-setting concrete based on a composite cement system and a preparation method thereof. The concrete comprises, by weight, 400 parts of water, 150 parts of (PO42.5) cement, 270 parts of (L.SAC52.5) ​​cement, 780 parts of sand, 1150 parts of crushed stone (5-20 mm), 30 parts of cellulose, 20 parts of polyvinyl alcohol, and 30 parts of an accelerating setting agent.

[0014] The method of this embodiment includes the following steps: S1: Put the cement, sand, gravel, cellulose and polyvinyl alcohol dry materials in the above weight ratio into a mixer and mix them evenly to prepare a dry mix; S2: adding 80% by weight of the water to the dry mix prepared in step S1, mixing well and letting it stand for 30 minutes, then adding the remaining 20% ​​by weight of the water, stirring and mixing well to prepare a concrete slurry; S3: Add the accelerator in the later stage of mixing and continue stirring to ensure that the accelerator is evenly dispersed in the concrete; S4: For poured quick-setting concrete, appropriate vibration should be carried out as needed to eliminate bubbles in the concrete and improve the density of the concrete.

[0015] S5: Drying, solidifying and curing the concrete slurry prepared in step S4.

[0016] The accelerator is composed of aluminum sulfate (Al2(SO4)3), sulfuric acid (H2SO4), aluminum hydroxide and polyacrylate in a mass ratio of (2:3:1:4). The preparation method of the accelerator includes the following steps: S1: Dissolve aluminum sulfate in water to prepare a certain concentration of aluminum sulfate solution, generally between 20% and 40%. During the dissolution process, appropriate heating and stirring can be performed to speed up the dissolution rate. The temperature is generally controlled between 40-60°C.

[0017] S2: Slowly add sulfuric acid to the aluminum sulfate solution while stirring, adjusting the solution's pH to within a certain range, typically between 2 and 4. Then, add an appropriate amount of aluminum hydroxide and continue stirring to allow the aluminum ions in the solution to fully react with sulfate ions and other ions to form an aluminum sulfate polymer. This polymerization reaction between aluminum ions and sulfate ions occurs under certain conditions, forming a polymer with a specific structure.

[0018] S3: Next, an organic polymer is added to interact with the aluminum sulfate polymer product, further modifying the properties of the accelerator. The reaction temperature is generally controlled between 60-80°C, and the reaction time is 3-8 hours. After the reaction is complete, the solution may contain unreacted solid impurities and some insoluble substances, which are removed by filtration to obtain a clear alkali-free accelerator solution. When aluminum sulfate dissolves in the cement paste, it rapidly releases aluminum ions, which react with hydroxide ions, sulfate ions, and other ions in the cement paste to form intermediate products, such as aluminum hydroxide gel. Intermediates such as aluminum hydroxide gel have strong adsorption and flocculation properties. They adsorb onto the surface of cement particles, interconnecting them to form a flocculated structure, causing the cement paste to quickly lose fluidity and achieve initial setting. As the reaction proceeds, trivalent aluminum ions, calcium ions, and sulfate ions in the solution further react to form ettringite. The formation and growth of ettringite further strengthens the flocculated structure, enabling the cement paste to set and harden rapidly, improving its early strength.

[0019] Example 2 Comparative Example 1 is another embodiment of the present invention; the accelerator is composed of aluminum sulfate (Al2(SO4)3), sulfuric acid (H2SO4), aluminum hydroxide and polyacrylate in a mass ratio of (2:5:1:4). By increasing the sulfuric acid ratio to further reduce the pH value of the mixture, a weaker alkaline accelerator solution can be obtained as required.

[0020] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0021] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. An early-strength quick-setting concrete based on a composite cement system, characterized by: By mass, it includes 400 parts of water, 400-460 parts of cement, 700-780 parts of sand, 980-1150 parts of crushed stone, 25-30 parts of cellulose, 18-26 parts of polyvinyl alcohol, and 30-35 parts of accelerating agent; The quick-setting agent is composed of aluminum sulfate (Al2(SO4)3), sulfuric acid (H2SO4), aluminum hydroxide and polyacrylate in a mass ratio of (2-3): (3-5): (1-2): (4-6).

2. The early-strength quick-setting concrete based on a composite cement system according to claim 1, characterized in that: The method for preparing the accelerating setting agent comprises the following steps: S1: Dissolve aluminum sulfate in water to prepare a certain concentration of aluminum sulfate solution, generally between 20% and 40%. During the dissolution process, appropriate heating and stirring can be performed to speed up the dissolution rate. The temperature is generally controlled between 40-60°C. S2: Slowly add sulfuric acid to the aluminum sulfate solution under stirring conditions to adjust the pH value of the solution to a certain range, generally between 2-4. Then add an appropriate amount of aluminum hydroxide and continue stirring to allow the aluminum ions in the solution to fully react with sulfate ions to form a polymerization product of aluminum sulfate. S3: Then, an organic high molecular polymer is added to interact with the aluminum sulfate polymerization product. The reaction temperature is controlled between 60-80°C and the reaction time is 3-8 hours. After the reaction is completed, impurities are removed by filtering to obtain a clear alkali-free accelerator solution.

3. The early-strength quick-setting concrete based on a composite cement system according to claim 1, characterized in that: The accelerator is composed of aluminum sulfate (Al2(SO4)3), sulfuric acid (H2SO4), aluminum hydroxide and polyacrylate in a mass ratio of 2:5:1:

4.

4. The method for preparing early-strength quick-setting concrete based on a composite cement system according to claim 1, characterized in that: The following steps are included S1: Put the cement, sand, gravel, cellulose and polyvinyl alcohol dry materials in the above weight ratio into a mixer and mix them evenly to prepare a dry mix; S2: adding 80% by weight of the water to the dry mix prepared in step S1, mixing well and letting it stand for 30 minutes, then adding the remaining 20% ​​by weight of the water, stirring and mixing well to prepare a concrete slurry; S3: Add the accelerator in the later stage of mixing and continue stirring to ensure that the accelerator is evenly dispersed in the concrete; S4: For poured quick-setting concrete, appropriate vibration should be carried out as needed to eliminate bubbles in the concrete and improve the density of the concrete. S5: Drying, solidifying and curing the concrete slurry prepared in step S4.

5. The method for preparing early-strength quick-setting concrete based on a composite cement system according to claim 1, characterized in that: By mass, it includes 400 parts of water, 150 parts of (p.o42.5) cement, 270 parts of (L.SAC52.5) ​​cement, 780 parts of sand, 1150 parts of crushed stone (5-20mm), 30 parts of cellulose, 20 parts of polyvinyl alcohol, and 30 parts of accelerating agent.