A high flowability concrete material and a method for producing the same

Abstract

The application belongs to the technical field of concrete, and relates to a high-fluidity concrete material and a preparation method thereof.The application has multiple improvement effects on concrete by adding a certain content of metal oxides, can improve the working performance of the concrete, reduces the cost, and improves important indexes such as the strength, durability and crack resistance of the concrete, and the biological carbon powder in the concrete can improve the mechanical properties, promote early hardening, improve the durability, and has the environment-friendly characteristics, and has important application value for building engineering.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology and relates to a high-flowability concrete material and its preparation method. Background Technology

[0002] In current commercial concrete mixing plants, the cementitious material content of ordinary C35 concrete is generally between 350 kg / m³ and 400 kg / m³, while its slump at the factory is typically 200 mm to 240 mm, and its spread is between 450 mm and 600 mm. A reasonable cementitious material content is a prerequisite for ensuring the workability of concrete. High-flowability concrete requires excellent water retention and encapsulation properties to achieve the goal of the cementitious paste driving aggregate spread, thus meeting the requirement of high flowability. In the common understanding in the construction industry, improving concrete workability requires increasing the amount of cementitious material. However, cementitious materials often have a saturation point; excessive dosage can be counterproductive. Abroad, there are already methods to produce low-cement, high-flowability concrete by optimizing the mix proportions, while maintaining good water retention and encapsulation properties.

[0003] Desulfurized gypsum, as a setting regulator for cement, results in the presence of SO42- in the cement hydration paste solution. SO42- competes with polycarboxylic acid molecules for adsorption on the surface of cement particles, preferentially adsorbing onto the cement particle surface. The higher the cement content, the more SO42- is relatively added, thereby reducing the adsorption rate of polycarboxylic acid by cement particles and leading to a decrease in the dispersion performance of polycarboxylic acid.

[0004] Excessive cementitious materials intensify the exothermic reaction during cement hydration, leading to high internal heat in the concrete and low external ambient temperature, resulting in a greater temperature difference. When the temperature drops sharply, tensile stress is induced on the concrete surface. When the tensile stress exceeds the concrete's bearing capacity, cracks will form. These cracks allow carbon dioxide and water to enter the concrete system, accelerating concrete carbonation. Overall, this has a certain impact on the early hydration reaction and later durability of the concrete.

[0005] Currently, the prices of cement, fly ash, mineral powder, and admixtures are all high in the market. Adding too much cementitious material to concrete keeps the cost of concrete high, which will have an adverse impact on mixing plants and the entire industry. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a high-flowability concrete material that can be obtained by adding a small amount of adhesive while ensuring the water retention and encapsulation properties of concrete. This reduces concrete costs, lowers early hydration heat, and maintains a good concrete condition.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A high-flowability concrete material, wherein the concrete comprises the following raw materials in parts by weight: 980-1100 parts coarse aggregate, 700-750 parts fine aggregate, 180-210 parts cement, 30-35 parts biochar powder, 5-15 parts metal oxide, 7-8 parts high-performance polycarboxylate superplasticizer, and 160-180 parts water.

[0009] This invention utilizes bio-carbon powder, which possesses a large specific surface area and high activity, to effectively fill micropores and cracks within concrete, increasing its density and strength, thereby improving its mechanical properties. Furthermore, bio-carbon powder acts as a catalyst, promoting hydration reactions within the cementitious matrix and accelerating the early hardening process of concrete. This shortens curing time and improves construction efficiency. Bio-carbon powder reduces the porosity of concrete, decreasing its permeability and water absorption, thus enhancing its durability. In addition, bio-carbon powder can adsorb and reduce harmful substances in concrete, such as heavy metal ions and organic pollutants, minimizing their erosion and damage. As an environmentally friendly material made from renewable biomass, bio-carbon powder is characterized by low carbon emissions and recyclability. Using bio-carbon powder in concrete can reduce carbon emissions, decrease the demand for traditional cement, and promote sustainable development in the construction industry.

[0010] In the aforementioned high-flowability concrete material, the coarse aggregate is crushed stone with a particle size of 5-25mm, wherein the crushed stone sand ratio is 41-43%.

[0011] This invention selects 5-25mm continuously graded aggregate. Excessively large aggregate in concrete can easily lead to poor concrete encapsulation. To achieve the maximum apparent density of concrete, continuously graded aggregate is used to avoid segregation of the concrete mixture, which results in poor water retention and encapsulation.

[0012] In the aforementioned high-flowability concrete material, the fine aggregate is rubber powder and calcined sand in a mass ratio of 1:(5-8).

[0013] In the aforementioned high-flowability concrete material, the calcined sand is yellow sand obtained by calcining at 800-850℃ for 50-60 minutes and holding at that temperature for 30-40 hours.

[0014] This invention involves calcining yellow sand to reduce the surface active substances of sand particles, such as calcium carbonate, after high-temperature treatment. This results in low gas content, low acid consumption, and low mud content in the yellow sand, thus ensuring the physical properties of the prepared concrete.

[0015] Ideally, the fineness modulus of the yellow sand should be 2.6. If the yellow sand is too fine, the concrete will have poor fluidity; if the yellow sand is too coarse, the concrete will have poor water retention and encapsulation.

[0016] In the aforementioned high-flowability concrete material, the cement loss on ignition is 3-4%, the magnesium chloride content is 1-3%, the sulfur trioxide content is 1-2%, the chloride ion content is 0.01-0.03%, and the specific surface area is 350-360 m². 2 / kg.

[0017] In the aforementioned high-flowability concrete material, the limestone powder has a particle size of 34-45 μm.

[0018] In the aforementioned high-flowability concrete material, the metal oxide includes at least one of aluminum oxide, iron oxide, and calcium oxide.

[0019] This invention improves the mechanical and durability properties of concrete by adding metal oxides. By controlling the amount of metal oxides added, the strength, hardness, and frost resistance of the concrete are guaranteed. Moreover, the metal oxides make the particles inside the concrete more uniformly dispersed, reducing cohesion and internal friction, thereby improving the flowability and workability of the concrete. Furthermore, the magnetic materials can enhance the paste structure of the concrete and improve the filling effect between particles, thereby reducing the amount of cement used, lowering costs, and ensuring the strength and durability of the concrete.

[0020] In the aforementioned high-flowability concrete material, the water reduction rate of the high-performance polycarboxylate superplasticizer is 30%-32%.

[0021] The present invention also provides a method for preparing the above-mentioned high-flowability concrete material, the method comprising the following steps:

[0022] S1: Prepare the above raw materials;

[0023] S2: Cement, metal oxides, and biochar powder are premixed, then fine and coarse aggregates are added and mixed. After uniform mixing, high-performance polycarboxylate superplasticizer is added and mixed with water. The water-cement ratio is adjusted to obtain high-flowability concrete material.

[0024] In the above-mentioned method for preparing a high-flowability concrete material, the water-cement ratio in step S2 is 0.62-0.84.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention improves concrete in many ways by adding a certain amount of metal oxides. It can improve the workability of concrete, reduce costs, and improve important indicators such as strength, durability, and crack resistance. When combined with bio-carbon powder in concrete, it can improve mechanical properties, promote early hardening, and enhance durability. It is also environmentally friendly and has important application value for construction engineering.

[0027] 2. The concrete material of the present invention only requires the addition of a small amount of adhesive to give it good flowability, water retention and encapsulation properties. Moreover, the overall preparation method of the present invention is simple and suitable for large-scale industrial production. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the high-flowability concrete material prepared in Example 1.

[0029] Figure 2 This is a schematic diagram of the high-flowability concrete material prepared in Example 4. Detailed Implementation

[0030] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0031] Example 1:

[0032] S1: Prepare the following proportions of raw materials by weight:

[0033] 1000 parts coarse aggregate, 720 parts fine aggregate, 190 parts cement, 32 parts biochar powder, 8 parts metal oxide, 7 parts high-performance polycarboxylate superplasticizer with a water reduction rate of 31%, and 175 parts water.

[0034] The coarse aggregate consists of crushed stone with an average particle size of 10 mm, and the crushed stone sand ratio is 42%.

[0035] The fine aggregate consists of rubber powder and calcined sand in a mass ratio of 1:6. The calcined sand is yellow sand obtained by calcining at 815℃ for 53 minutes and holding at that temperature for 36 hours.

[0036] The cement has a loss on ignition of 2%, a magnesium chloride content of 1.8%, a sulfur trioxide content of 2%, a chloride ion content of 0.02%, and a specific surface area of ​​360 m². 2 / kg.

[0037] The metal oxides are calcium oxide and iron oxide in a mass ratio of 1:1.

[0038] S2: Cement, metal oxides, and biochar powder are premixed, then fine and coarse aggregates are added and mixed. After uniform mixing, high-performance polycarboxylate superplasticizer is added and mixed with water, and the water-cement ratio is adjusted to 0.72 to obtain the desired result. Figure 1 The high-flowability concrete material shown in the figure has good encapsulation and water retention properties.

[0039] Example 2:

[0040] S1: Prepare the following proportions of raw materials by weight:

[0041] 980 parts coarse aggregate, 700 parts fine aggregate, 180 parts cement, 30 parts biochar powder, 5 parts metal oxide, 7 parts high-performance polycarboxylate superplasticizer with a water reduction rate of 30%, and 160 parts water.

[0042] The coarse aggregate consists of crushed stone with an average particle size of 10 mm, and the crushed stone sand ratio is 41%.

[0043] The fine aggregate consists of rubber powder and calcined sand in a mass ratio of 1:5. The calcined sand is yellow sand obtained by calcining at 800℃ for 50 minutes and holding at that temperature for 30 hours.

[0044] The cement has a loss on ignition of 1%, a magnesium chloride content of 1%, a sulfur trioxide content of 1%, a chloride ion content of 0.01%, and a specific surface area of ​​350 m². 2 / kg.

[0045] The metal oxide is calcium oxide.

[0046] S2: Cement, metal oxides, and biochar powder are premixed, then fine and coarse aggregates are added and mixed. After uniform mixing, high-performance polycarboxylate superplasticizer and water are added and mixed. The water-cement ratio is adjusted to 0.70 to obtain high-flowability concrete material.

[0047] Example 3:

[0048] S1: Prepare the following proportions of raw materials by weight:

[0049] 1100 parts coarse aggregate, 750 parts fine aggregate, 210 parts cement, 35 parts biochar powder, 15 parts metal oxide, 8 parts high-performance polycarboxylate superplasticizer with a water reduction rate of 32%, and 180 parts water.

[0050] The coarse aggregate consists of crushed stone with an average particle size of 25mm, and the crushed stone sand ratio is 43%.

[0051] The fine aggregate consists of rubber powder and calcined sand in a mass ratio of 1:8. The calcined sand is yellow sand obtained by calcining at 850℃ for 60 minutes and holding at that temperature for 40 hours.

[0052] The cement has a loss on ignition of 3%, a magnesium chloride content of 2%, a sulfur trioxide content of 3%, a chloride ion content of 0.03%, and a specific surface area of ​​380 m². 2 / kg.

[0053] The metal oxide is iron oxide.

[0054] S2: Cement, metal oxides, and biochar powder are premixed, then fine and coarse aggregates are added and mixed. After uniform mixing, high-performance polycarboxylate superplasticizer and water are added and mixed. The water-cement ratio is adjusted to 0.76 for high-flowability concrete.

[0055] Example 4:

[0056] The only difference from Example 1 is that the fine aggregate in Example 5 is only yellow sand that has not undergone calcination treatment.

[0057] The prepared concrete material, such as Figure 2 As shown in the figure, the prepared concrete material only has good water retention but poor encapsulation.

[0058] Example 5:

[0059] The only difference from Example 1 is that the yellow sand in the fine aggregate of Example 4 was not roasted.

[0060] Example 6:

[0061] The only difference from Example 1 is that the fine aggregate in Example 6 is rubber powder and calcined sand in a mass ratio of 1:1.

[0062] Comparative Example 1:

[0063] The only difference from Example 1 is that no bio-carbon powder was added in Comparative Example 1.

[0064] Comparative Example 2:

[0065] The only difference from Example 1 is that the amount of bio-carbon powder added in Comparative Example 2 is 10 parts.

[0066] Comparative Example 3:

[0067] The only difference from Example 1 is that the amount of bio-carbon powder added in Comparative Example 3 is 45 parts.

[0068] Comparative Example 4:

[0069] The only difference from Example 1 is that no metal oxide was added in Comparative Example 4.

[0070] Comparative Example 5:

[0071] The only difference from Example 1 is that the amount of metal oxide added in Comparative Example 5 is 1 part.

[0072] Comparative Example 6:

[0073] The only difference from Example 1 is that the amount of metal oxide added is 25 parts.

[0074] The flowability, flexural strength, and compressive strength of the concrete materials prepared in Examples 1-6 and Comparative Examples 1-6 were tested respectively.

[0075] The flexural strength and compressive strength were tested according to the ISO method for testing the strength of cement mortar (GB / T17671-1999), and the 28-day flexural strength and 28-day compressive strength were tested.

[0076] Table 1: Performance test results of concrete materials prepared in Examples 1-6 and Comparative Examples 1-6

[0077]

[0078]

[0079] In summary, this invention improves concrete in many ways by adding metal oxides, enhancing its workability, reducing costs, and improving key indicators such as strength, durability, and crack resistance. Combined with bio-carbon powder, it can improve mechanical properties, promote early hardening, and enhance durability, while also being environmentally friendly, making it of significant application value in construction engineering.

[0080] The embodiments described herein cover any points not exhaustively within the scope of the technical claims of this invention, as well as new technical solutions formed by equivalent substitutions of one or more technical features in the embodiments. These are all within the scope of the claims of this invention. Furthermore, in all listed or unlisted embodiments of this invention, each parameter in the same embodiment merely represents an instance (i.e., a feasible solution) of its technical solution, and there is no strict coordination or limitation relationship between the parameters. The parameters can be substituted for each other without violating axioms and the claims of this invention, unless otherwise stated.

[0081] The technical means disclosed in this invention are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above descriptions are specific embodiments of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A high-flowability concrete material, characterized in that, The concrete comprises the following raw materials in parts by weight: 980-1100 parts coarse aggregate, 700-750 parts fine aggregate, 180-210 parts cement, 30-35 parts biochar powder, 5-15 parts metal oxide, 7-8 parts high-performance polycarboxylate superplasticizer, and 160-180 parts water. The coarse aggregate is crushed stone with a particle size of 5-25mm, of which the crushed stone sand ratio is 41-43%; The fine aggregate is rubber powder and calcined sand in a mass ratio of 1:(5-8); The roasted sand is yellow sand obtained by roasting at 800-850℃ for 50-60 minutes and holding it at that temperature for 30-40 hours. The cement has a loss on ignition of 1-3%, a magnesium chloride content of 1-2%, a sulfur trioxide content of 1-3%, a chloride ion content of 0.01-0.03%, and a specific surface area of ​​350-380 m². 2 / kg; Metal oxides include at least one of aluminum oxide, iron oxide, and calcium oxide; High-performance polycarboxylate superplasticizers have a water reduction rate of 30%-32%.

2. A method for preparing a high-flowability concrete material as described in claim 1, characterized in that, The method includes the following steps: S1: Raw materials for preparing the concrete material as described in claim 1; S2: Cement, metal oxides, and biochar powder are premixed, then fine and coarse aggregates are added and mixed. After uniform mixing, high-performance polycarboxylate superplasticizer is added and mixed with water. The water-cement ratio is adjusted to obtain high-flowability concrete material.

3. The method for preparing a high-flowability concrete material according to claim 2, characterized in that, The water-to-glue ratio in step S2 is 0.62-0.84.

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