A kind of crack-resistant concrete and preparation method thereof

Abstract

The present invention relates to the technical field of concrete, and proposes a crack-resistant concrete and a preparation method thereof. The crack-resistant concrete comprises the following raw materials by weight: 60-70 parts of cement, 90-110 parts of medium sand, 170-180 parts of crushed stone, 20-30 parts of water, 2-3 parts of water reducer, 3-10 parts of fly ash, and 25-35 parts of blast furnace slag powder; the blast furnace slag powder is composed of a first blast furnace slag powder and a second blast furnace slag powder, the first blast furnace slag powder and the second blast furnace slag powder have different activity indexes, and the mass ratio of the first blast furnace slag powder to the second blast furnace slag powder is 1:3-3:1. Through the above technical scheme, the problem of easy cracking of concrete in the related art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and in particular to a crack-resistant concrete and a preparation method thereof. Background Art

[0002] In modern construction projects, concrete, as a widely used building material, plays a vital role. Concrete is an artificial stone made of cement, sand, water and admixtures in a certain proportion. It has the advantages of high strength, good durability and relatively low cost, and is widely used in various building structures, roads and bridges, water conservancy projects and other fields.

[0003] However, concrete often faces the problem of cracking during use. For example, in large-scale water conservancy projects, concrete is in a humid environment for a long time and is subjected to huge water pressure. The anti-cracking performance is directly related to the safety and durability of the project; in road and bridge projects, concrete pavements and bridge structures need to withstand repeated loads from vehicles and erosion from the natural environment. Anti-cracking can ensure their long-term stable operation; in addition, in some construction projects with high requirements for appearance, such as high-end office buildings and commercial centers, anti-cracking concrete can ensure the beauty and quality of the building. It can be seen that anti-cracking is crucial for concrete structures. Therefore, it is extremely necessary to develop a crack-resistant concrete. Summary of the invention

[0004] The invention provides a crack-resistant concrete and a preparation method thereof, which solves the problem of easy cracking of concrete in the related art.

[0005] The technical scheme of the present invention is as follows: The present invention provides a crack-resistant concrete and a preparation method thereof, comprising the following raw materials in parts by weight: 60-70 parts of cement, 90-110 parts of medium sand, 170-180 parts of crushed stone, 20-30 parts of water, 2-3 parts of water reducing agent, 3-10 parts of fly ash, and 25-35 parts of blast furnace slag powder;

[0006] The blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder, the first blast furnace slag powder and the second blast furnace slag powder have different activity indexes, and the mass ratio of the first blast furnace slag powder to the second blast furnace slag powder is 1:3~3:1.

[0007] As a further technical solution, the activity index of the first blast furnace slag powder is classified as S95, the activity index of the second blast furnace slag powder is classified as S105, and the mass ratio of the first blast furnace slag powder to the second blast furnace slag powder is 2~3:3.

[0008] As a further technical solution, the raw material also includes 1 to 1.5 parts of fiber reinforcement material.

[0009] In the present invention, fiber reinforcement material is added as a raw material to play a bridging role in the concrete matrix, delay the development of cracks, enhance the toughness of concrete, and improve the crack resistance of concrete.

[0010] As a further technical solution, the fiber reinforcement material includes one or more of polypropylene fiber, carbon fiber, and glass fiber.

[0011] As a further technical solution, when the fiber reinforcement material is polypropylene fiber, the polypropylene fiber is modified polypropylene fiber, and the modifier of the modified polypropylene fiber is an indoleacetamide compound.

[0012] In the present invention, indoleacetamide compounds are used to modify polypropylene fibers, thereby enhancing the bonding force between the polypropylene fibers and the concrete matrix, making the microstructure of the concrete denser, and further improving the crack resistance of the concrete.

[0013] As a further technical solution, the indoleacetamide compound includes one or more of 5-hydroxyindole-3-acetamide, 3-indoleacetamide, and N-phenyl-1H-indole-3-acetamide.

[0014] In the present invention, N-phenyl-1H-indole-3-acetamide is preferably used as the modifier. The benzene ring structure of N-phenyl-1H-indole-3-acetamide increases the spatial structural complexity and conjugation degree of the compound, which is beneficial to maintaining the performance of the fiber and further improving the crack resistance of the concrete.

[0015] As a further technical solution, the preparation method of the modified polypropylene fiber comprises the following steps: dissolving the modifier in a solvent, adding polypropylene fiber, soaking and drying to obtain the modified polypropylene fiber.

[0016] As a further technical solution, the raw material of the modified polypropylene fiber includes a modifier and polypropylene fiber in a mass ratio of 1 to 2:40.

[0017] As a further technical solution, the type of cement is ordinary Portland cement with a strength grade of 42.5.

[0018] As a further technical solution, the water reducer includes one or both of aminocarboxylic acid water reducer and polycarboxylic acid water reducer.

[0019] The present invention also provides a method for preparing crack-resistant concrete, comprising the following steps: weighing the component raw materials by weight, mixing and stirring evenly, and obtaining the crack-resistant concrete after curing.

[0020] The working principle and beneficial effects of the present invention are:

[0021] In the present invention, cement, medium sand, crushed stone, water, water reducing agent, fly ash and blast furnace slag powder are used as raw materials, a first blast furnace slag powder and a second blast furnace slag powder with different activity indexes are mixed for use, and the mass ratio of the two is coordinated to exert the synergistic effect of the two, optimize the voids inside the concrete, improve the impermeability of the concrete, reduce the temperature stress of cement water thermalization, reduce the generation of shrinkage cracks, and improve the crack resistance of the concrete. DETAILED DESCRIPTION

[0022] 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 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.

[0023] In the following examples and comparative examples:

[0024] Cement: Ordinary Portland cement P·O, strength grade 42.5;

[0025] Crushed stone: continuous particle size 5~25mm, void ratio 42%, bulk density 1560kg / m 3 ;

[0026] Medium sand: machine-made sand, porosity 44%, bulk density 1450kg / m 3 ;

[0027] Polypropylene fiber: fiber length 1.2mm, diameter 18μm;

[0028] Carbon fiber: 9 mm in length and 7 μm in diameter;

[0029] Polycarboxylate water reducer: Model: HK41274, water reduction rate: 28%, water bleeding rate: 45%;

[0030] First blast furnace slag powder: S95 grade;

[0031] Second blast furnace slag powder: S105 grade;

[0032] Gray coal powder: Class F, activity index 75.8%.

[0033] Example 1

[0034] A method for preparing crack-resistant concrete comprises the following steps: weighing 60 parts of cement, 90 parts of medium sand, 170 parts of crushed stone, 20 parts of water, 2 parts of polycarboxylic acid water-reducing agent, 3 parts of fly ash, and 25 parts of blast furnace slag powder, mixing and stirring evenly, and obtaining the crack-resistant concrete after standard curing for 7 days; wherein the blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder in a mass ratio of 1:3.

[0035] Example 2

[0036] A method for preparing crack-resistant concrete comprises the following steps: weighing 66 parts of cement, 98 parts of medium sand, 173 parts of crushed stone, 26 parts of water, 2.8 parts of polycarboxylic acid water-reducing agent, 5 parts of fly ash, and 29 parts of blast furnace slag powder, mixing and stirring evenly, and obtaining the crack-resistant concrete after standard curing for 7 days; wherein the blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder in a mass ratio of 1:3.

[0037] Example 3

[0038] A method for preparing crack-resistant concrete comprises the following steps: weighing 70 parts of cement, 110 parts of medium sand, 180 parts of crushed stone, 30 parts of water, 3 parts of polycarboxylic acid water-reducing agent, 10 parts of fly ash, and 35 parts of blast furnace slag powder, mixing and stirring evenly, and obtaining the crack-resistant concrete after standard curing for 7 days; wherein the blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder in a mass ratio of 3:1.

[0039] Example 4

[0040] Compared with Example 2, the difference of Example 4 is that the blast furnace slag powder consists of the first blast furnace slag powder and the second blast furnace slag powder in a mass ratio of 2:3.

[0041] Example 5

[0042] Compared with Example 2, the difference in Example 5 is that the blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder in a mass ratio of 3:3.

[0043] Example 6

[0044] Compared with Example 2, the difference in Example 6 is that the blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder in a mass ratio of 3:2.

[0045] Example 7

[0046] A method for preparing crack-resistant concrete comprises the following steps: weighing 66 parts of cement, 98 parts of medium sand, 173 parts of crushed stone, 26 parts of water, 2.8 parts of polycarboxylic acid water reducer, 5 parts of fly ash, 29 parts of blast furnace slag powder, and 1 part of polypropylene fiber, mixing and stirring evenly, and obtaining the crack-resistant concrete after standard curing for 7 days; wherein the blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder in a mass ratio of 3:3.

[0047] Example 8

[0048] A method for preparing crack-resistant concrete comprises the following steps: weighing 66 parts of cement, 98 parts of medium sand, 173 parts of crushed stone, 26 parts of water, 2.8 parts of polycarboxylic acid water reducer, 5 parts of fly ash, 29 parts of blast furnace slag powder, and 1.5 parts of carbon fiber, mixing and stirring evenly, and obtaining the crack-resistant concrete after standard curing for 7 days; wherein the blast furnace slag powder consists of a first blast furnace slag powder and a second blast furnace slag powder in a mass ratio of 3:3.

[0049] Example 9

[0050] The preparation method of modified polypropylene fiber comprises the following steps: dissolving 0.1 parts of 5-hydroxyindole-3-acetamide in 10 parts of dimethylformamide, soaking 2 parts of polypropylene fiber in 20 parts of anhydrous ethanol solution for 12 hours, filtering and drying to constant weight to obtain pretreated polypropylene fiber, adding the pretreated polypropylene fiber into the solution of 5-hydroxyindole-3-acetamide, soaking for 12 hours, and drying to obtain modified polypropylene fiber;

[0051] Compared with Example 7, the difference of Example 9 is that the polypropylene fiber is replaced by an equal amount of modified polypropylene fiber obtained by the above preparation method.

[0052] Example 10

[0053] Compared with Example 9, the difference in Example 10 is that the added amount of 5-hydroxyindole-3-acetamide is 0.05 parts.

[0054] Embodiment 11

[0055] Compared with Example 9, Example 11 is different in that 5-hydroxyindole-3-acetamide is replaced by an equal amount of 3-indoleacetamide.

[0056] Example 12

[0057] Compared with Example 9, Example 12 is different in that 5-hydroxyindole-3-acetamide is replaced by an equal amount of N-phenyl-1H-indole-3-acetamide.

[0058] Comparative Example 1

[0059] Compared with Example 2, the difference in Comparative Example 1 is that the second blast furnace slag powder is replaced with an equal amount of the first blast furnace slag powder.

[0060] Comparative Example 2

[0061] Compared with Example 2, the difference of Comparative Example 2 is that the first blast furnace slag powder is replaced by an equal amount of the second blast furnace slag powder.

[0062] The crack-resistant concretes prepared in Examples 1 to 12 and Comparative Examples 1 to 2 were tested according to the following method:

[0063] 1. Crack resistance: The crack-resistant concrete obtained after standard curing for 7 days was placed in an environment with a humidity of 90% and a temperature of 25°C for curing. Whether cracks appeared on the concrete surface was observed after 12 days and 24 days respectively.

[0064] 2. Compressive strength: According to the test method specified in GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", the compressive strength of the samples was tested at 7d and 28d.

[0065] The test results are shown in the following table:

[0066] Table 1 Performance test results of crack-resistant concrete prepared in Examples 1 to 12 and Comparative Examples 1 to 2

[0067]

[0068] Compared with Comparative Examples 1 and 2, Example 2 simultaneously adds the first blast furnace slag powder and the second blast furnace slag powder. As a result, the crack resistance and compressive strength of Example 2 are better than those of Comparative Examples 1 and 2, indicating that the first blast furnace slag powder and the second blast furnace slag powder play a synergistic role and can improve the crack resistance of concrete. Compared with Example 2, Examples 4 to 6 add the first blast furnace slag powder and the second blast furnace slag powder in different mass ratios. As a result, the compressive strength of Examples 4 and 5 is better than that of Examples 2 and 6, indicating that when the mass ratio of the first blast furnace slag powder to the second blast furnace slag powder is 2 to 3:3, the obtained concrete has better crack resistance.

[0069] Compared with Example 5, Examples 7 and 8 added fiber reinforcement materials. As a result, the compressive strength of Examples 7 and 8 was better than that of Example 5, indicating that the addition of fiber reinforcement materials can improve the crack resistance of concrete.

[0070] Compared with Example 7, Examples 9 to 12 added modified polypropylene fibers modified by indoleacetamide compounds. As a result, the compressive strength of Examples 9 to 12 was better than that of Example 7, indicating that the addition of modified polypropylene fibers can improve the crack resistance of concrete.

[0071] In Examples 9, 11, and 12, different types of indoleacetamide compounds were added to modify polyacrylamide. As a result, the compressive strength of Example 12 was better than that of Examples 9 and 11, indicating that when the modifier used was N-phenyl-1H-indole-3-acetamide, the resulting concrete had better crack resistance.

[0072] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A crack-resistant concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 60-70 parts of cement, 90-110 parts of medium sand, 170-180 parts of crushed stone, 20-30 parts of water, 2-3 parts of water reducing agent, 3-10 parts of fly ash, and 25-35 parts of blast furnace slag powder; the blast furnace slag powder is composed of a first blast furnace slag powder and a second blast furnace slag powder, the first blast furnace slag powder and the second blast furnace slag powder have different activity indexes, and the mass ratio of the first blast furnace slag powder to the second blast furnace slag powder is 1:3-3:1; The raw materials also include 1 to 1.5 parts of fiber reinforcement material; The fiber reinforcement material includes polypropylene fibers; The polypropylene fiber is a modified polypropylene fiber, and the modifier of the modified polypropylene fiber is an indoleacetamide compound; The indoleacetamide compound includes one or more of 5-hydroxyindole-3-acetamide, 3-indoleacetamide, and N-phenyl-1H-indole-3-acetamide; The preparation method of the modified polypropylene fiber comprises the following steps: dissolving the modifier in a solvent, adding polypropylene fiber, soaking and drying to obtain the modified polypropylene fiber.

2. The crack-resistant concrete according to claim 1, characterized in that: The activity index of the first blast furnace slag powder is classified as S95, the activity index of the second blast furnace slag powder is classified as S105, and the mass ratio of the first blast furnace slag powder to the second blast furnace slag powder is 2~3:

3.

3. The crack-resistant concrete according to claim 1, characterized in that: The model of the cement is ordinary Portland cement, and the strength grade is 42.

5.

4. The crack-resistant concrete according to claim 1, characterized in that: The water reducer includes one or both of aminocarboxylic acid water reducer and polycarboxylic acid water reducer.

5. The method for preparing crack-resistant concrete according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: weighing the component raw materials in parts by weight, mixing and stirring evenly, and obtaining the crack-resistant concrete after curing.

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