Ultra-high compressive strength and high ductility concrete for reinforcement and its preparation and application

Abstract

The invention discloses a super high compressive strength and high ductility concrete for reinforcement, comprising raw material components such as cement, silica fume, fly ash, 20-40 mesh sand, 40-70 mesh sand, water reducer, cellulose ether, defoamer, rheological agent, water and anti-cracking fiber, and the compressive strength of the concrete is as high as 80MPa or more. The concrete material of the invention breaks through the limitation of the compressive strength of conventional high ductility concrete, and is successfully used for reinforcement and renovation of seriously aged abandoned buildings, so that the main body of the building after renovation can meet the performance standards of compressive strength, bending strength and the like, and provides a feasible and effective solution for the renovation and reuse of abandoned buildings.

Description

Technical Field

[0001] The invention relates to the technical field of concrete materials, in particular to a high-ductility concrete with ultra-high compressive strength for reinforcement, as well as the preparation and application of the concrete. Background Art

[0002] As my country's real estate economy is in a downturn, some unfinished buildings have been shelved, resulting in the emergence of unfinished buildings, which seriously affects the urban landscape. If they are demolished, it will cause great economic losses. Therefore, most of the shelved buildings need to be renovated and put back into use. However, due to long-term shelving, the buildings have problems such as rusted steel bars and aging concrete, resulting in the structural strength being unable to meet the subsequent use requirements. Therefore, it is necessary to increase the strength performance of the shelved buildings through reinforcement plans to meet the use requirements.

[0003] The development of highly ductile concrete with ultra-high compressive strength is crucial for the reinforcement and renovation of abandoned buildings. Summary of the invention

[0004] In order to solve the deficiencies of the above-mentioned prior art, the present invention provides a high-ductility concrete with ultra-high compressive strength. Through the optimization and compounding of raw material components, a breakthrough in the compressive strength of high-ductility concrete is achieved, and the compressive strength is successfully reached to more than 80Mpa, providing a feasible and effective solution for the renovation and reuse of abandoned buildings.

[0005] To achieve the above-mentioned purpose, the present invention provides a reinforced ultra-high compressive strength high ductility concrete, the raw material composition of which includes cementitious materials, auxiliary materials, water and anti-cracking fibers;

[0006] The cementitious material includes 300-600 parts of cement, 40-100 parts of silica fume, 100-300 parts of fly ash, 100-200 parts of 20-40 mesh sand, and 50-150 parts of 40-70 mesh sand;

[0007] The auxiliary materials include 0.1 to 3 parts of water reducing agent, 0.1 to 2 parts of cellulose ether, 0.1 to 1.5 parts of defoaming agent, and 0.1 to 1.5 parts of rheological agent;

[0008] The amount of water used is 16% to 18% of the total amount of the gelling material and auxiliary materials;

[0009] The dosage of anti-cracking fiber is 4‰ to 7‰ of the total amount of cementitious materials, auxiliary materials and water;

[0010] The concrete meets the technical indicators of high ductility concrete, specifically equivalent bending toughness (quick test) ≥ 170kJ / m 3 , equivalent bending strength (quick test) ≥11MPa, flexural strength ≥11MPa, and compressive strength ≥80MPa.

[0011] The present invention achieves synergistic effects among the raw materials by screening the raw materials and adjusting the component ratio, thereby achieving a substantial improvement in compressive strength while meeting the technical indicators of high-ductility concrete. The raw material composition of the concrete of the present invention includes cementitious materials, auxiliary materials, water and anti-cracking fibers. Cement, silica fume, fly ash and two kinds of mesh sand constitute the cementitious materials, wherein cement is used as the main material and sand is used as the skeleton to provide the main compressive strength for the concrete. Silica fume, fly ash and cement work together to improve the workability of the concrete, increase the later strength and reduce the cost at the same time. The addition of water reducer, cellulose ether and rheological agent in the auxiliary materials can synergistically improve the workability of the materials, making the concrete soft to apply, having good thixotropy and convenient construction; the defoamer is used to reduce the foaming of the concrete system and improve the compressive and toughness resistance. In addition, in the compounding of concrete, the amount of water added needs to be controlled at 16% to 18% of the total amount of cementitious materials and auxiliary materials, and the amount of anti-cracking fiber added needs to be controlled at 4‰ to 7‰ of the total amount of cementitious materials, auxiliary materials and water. This can not only completely hydrate the cementitious materials to ensure construction performance, but also ensure the excellent properties of concrete such as compressive strength and toughness.

[0012] As a limitation of the above technical solution, the cementitious material includes 370-430 parts of cement, 56-72 parts of silica fume, 180-250 parts of fly ash, 130-200 parts of 20-40 mesh sand, and 50-110 parts of 40-70 mesh sand;

[0013] The auxiliary materials include 0.9-1.6 parts of water reducing agent, 0.8-1.4 parts of cellulose ether, 0.6-1.2 parts of defoaming agent, and 0.2-0.8 parts of rheological agent;

[0014] The amount of water used is 16% to 17.5% of the total amount of the cementitious material and auxiliary materials;

[0015] The amount of anti-cracking fiber used is 5‰ to 6‰ of the total amount of gelling material, auxiliary materials and water.

[0016] As a limitation of the above technical solution, the cement is 525 cement, the sand is quartz sand, and the dosage ratio of cement to sand is (1.16-3):1, preferably (1.45-1.85):1.

[0017] 525 cement and quartz sand are selected, and the dosage of the two raw materials is limited to ensure the high compressive strength of the concrete.

[0018] As a limitation of the above technical solution, the water reducing agent is a polycarboxylic acid water reducing agent or a naphthalenesulfonate formaldehyde condensation polymer water reducing agent, and the water reducing rate is required to be 20% to 45%.

[0019] As a limitation to the above technical solution, the cellulose ether is selected from methyl cellulose ether or methyl hydroxyethyl cellulose ether.

[0020] As a limitation of the above technical solution, it is required that the defoaming agent is suitable for high viscosity system, and the air content of the grouting material is ≤3% after using the defoaming agent. The defoaming agent is a polyether defoaming agent or a fatty acid defoaming agent.

[0021] The use of defoamers suitable for high viscosity systems has high viscosity and can minimize the foaming of concrete mixes, thereby ensuring compressive and toughness resistance.

[0022] As a limitation of the above technical solution, the rheological agent is a hydroxy starch ether or hydroxypropyl starch ether solution with a viscosity ranging from 1000 to 3000 mPa·s.

[0023] As a limitation of the above technical solution, the anti-cracking fiber is selected from polyethylene fiber, and the length of the polyethylene fiber is required to be 10-20 mm and the diameter is 50-100 μm.

[0024] The anti-cracking fiber is made of polyethylene fiber, which has sufficient toughness, but should not be too long or too thick in diameter, otherwise it will affect the mixing time and construction workability.

[0025] Further improve the formula of concrete, optimize material performance, and facilitate construction operations.

[0026] The present invention provides a method for preparing the ultra-high compressive strength and high ductility concrete for reinforcement as described above, which comprises mixing the other raw material components except the anti-cracking fiber according to the formula amount, adding the anti-cracking fiber after fully stirring, and continuing to stir evenly to obtain the ultra-high compressive strength and high ductility concrete that can be directly used in construction.

[0027] At the same time, the present invention also provides the application of the ultra-high compressive strength and high ductility concrete for reinforcement as described above, that is, for the reinforcement of concrete, especially suitable for the reinforcement of concrete shear walls.

[0028] The ultra-high compressive strength and high ductility concrete of the present invention can be directly applied to the wall for construction use only by fully stirring other raw materials and finally adding the anti-cracking fiber and stirring and mixing evenly. The operation is simple and convenient, and the concrete can be used for reinforcing and renovating the main body of the building, and is particularly suitable for reinforcing the shear wall.

[0029] In summary, the present invention obtains a high-ductility concrete with ultra-high compressive strength by screening and compounding the formula raw materials to achieve synergy between the raw materials, breaking through the limitation of conventional high-ductility concrete in compressive strength, reaching a compressive strength of more than 80MPa, and successfully used for the reinforcement and renovation of the main body of the building, especially suitable for buildings that are seriously aged due to long-term shelving, and used for the reinforcement of the main shear wall, so that the renovated building can have a certain toughness while having high compressive strength, greatly reducing the risk of damage and collapse, and achieving the purpose of reusing the shelved building. In addition, the concrete of the present invention is convenient to construct, and it only needs to fully stir and mix the components as required, and then it can be directly constructed, providing a feasible and effective solution for the repair and reuse of shelved buildings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 , photos of the mixing process of concrete in Example 1;

[0031] Figure 2 , Photo of the concrete after mixing in Example 1;

[0032] Figure 3 , Photo of the concrete wall status in Example 1;

[0033] Figure 4 , Photo of the concrete test block of Example 1 after the bending test;

[0034] Figure 5 , Comparative Example 2: Photos of the concrete wall effect. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. 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.

[0036] The raw materials used in the following examples and comparative examples are typical products purchased from the market.

[0037] Example 1

[0038] A super high compressive strength and high ductility concrete, the formula is:

[0039]

[0040] Mix the other raw material components except the anti-cracking fiber according to the formula, such as Figure 1 As shown, stir thoroughly for about 2 to 3 minutes until the mixture is uniform, then add the anti-cracking fiber, and continue stirring for 2 to 3 minutes until the mixture is uniform, so as to obtain concrete that can be directly used for construction, as shown in FIG. Figure 2 As shown; during construction, the evenly mixed concrete is directly applied to the wall to be repaired. The actual construction situation is shown in Figure 3 .

[0041] After testing, the concrete performance results are shown in the table below.

[0042]

[0043]

[0044] After the concrete specimen has completed the bending test, the state of the specimen is as follows: Figure 4 As shown, the bending damage state of the specimen is normal, meeting the requirements of flexural toughness of high ductility concrete.

[0045] Example 2

[0046] Ultra-high compressive strength, high ductility concrete, the formula is:

[0047]

[0048] Ultra-high compressive strength, high ductility concrete, the formula is:

[0049]

[0050]

[0051] The raw material components used in Examples 2 and 3 are adjusted within the dosage range to maintain the mechanical properties of the concrete and meet the equivalent bending toughness (quick test) ≥ 170 kJ / m 3 , equivalent bending strength (quick test) ≥11MPa, flexural strength ≥11MPa, compressive strength ≥80MPa, meeting the requirements for use.

[0052] Comparative Example 1

[0053] An existing high ductility concrete for reinforcement has the following specific formula:

[0054]

[0055] The performance of the test block is shown in the following table:

[0056]

[0057]

[0058] The compressive strength of the existing commonly used high-ductility concrete is far below the requirement of 80MPa and cannot meet the needs of reinforcement.

[0059] Comparative Example 2

[0060] A high ductility concrete, which is different from the high ductility concrete of the present invention in terms of the raw material dosage ratio, the properties of the water reducer, defoamer, rheological agent and the specifications of the anti-cracking fiber, and the specific formula is as follows:

[0061]

[0062] After all components are mixed evenly according to the mixing method in the embodiment, the wall effect is shown in the attached Figure 5 , poor thixotropy, obvious flow; the test block performance is as follows:

[0063] Test items Test results <![CDATA[Equivalent flexural toughness (quick test), kJ / m 3 > 158.8 <![CDATA[Equivalent flexural strength (quick test), N / mm 2 > 11.2 <![CDATA[Flexural strength (quick test), N / mm 2 > 10.8 <![CDATA[Compressive strength (quick test), N / mm 2 > 46.2

[0064] Comparative Example 3

[0065] A high ductility concrete, which is different from the high ductility concrete of the present invention in terms of the raw material dosage ratio, the properties of the defoamer and rheological agent used, and the specifications of the anti-cracking fiber. The specific formula is as follows:

[0066]

[0067] The final test block performance is as follows:

[0068] Test items Test results <![CDATA[Equivalent flexural toughness (quick test), kJ / m 3 > 332.2 <![CDATA[Equivalent flexural strength (quick test), N / mm 2 > 10.1 <![CDATA[Flexural strength (quick test), N / mm 2 > 9.1 <![CDATA[Compressive strength (quick test), N / mm 2 > 39.9

[0069] It can be seen from Comparative Examples 2 and 3 that the ratio of raw material components in the concrete formula and the performance requirements of the raw materials used as auxiliary materials will directly affect the strength and toughness of the concrete, and thus affect the concrete's difficulty in meeting the requirements during reinforcement use.

[0070] In summary, the ultra-high compressive strength and high ductility concrete for reinforcement of the present invention has a compressive strength of more than 80 MPa, breaking through the limitation of conventional high ductility concrete in compressive strength, and is successfully used for main body reinforcement and renovation of seriously aged abandoned buildings, so that the main body of the building after renovation can meet the performance standards such as compressive strength and bending strength, and the construction is convenient, providing a feasible and effective solution for the renovation and reuse of abandoned buildings.

Claims

1. A super high compressive strength and high ductility concrete for reinforcement, characterized in that: Its raw material composition includes gelling material, auxiliary material, water and anti-cracking fiber; The cementitious material includes 300-600 parts of cement, 40-100 parts of silica fume, 100-300 parts of fly ash, 100-200 parts of 20-40 mesh sand, and 50-150 parts of 40-70 mesh sand; The auxiliary materials include 0.1 to 3 parts of water reducing agent, 0.1 to 2 parts of cellulose ether, 0.1 to 1.5 parts of defoaming agent, and 0.1 to 1.5 parts of rheological agent; The amount of water used is 16% to 18% of the total amount of the gelling material and auxiliary materials; The dosage of anti-cracking fiber is 4‰ to 7‰ of the total amount of cementitious materials, auxiliary materials and water; The concrete meets the technical indicators of high ductility concrete and has a compressive strength of ≥80MPa.

2. The ultra-high compressive strength and high ductility concrete for reinforcement according to claim 1, characterized in that: The cementitious material includes 370-430 parts of cement, 56-72 parts of silica fume, 180-250 parts of fly ash, 130-200 parts of 20-40 mesh sand, and 50-110 parts of 40-70 mesh sand; The auxiliary materials include 0.9-1.6 parts of water reducing agent, 0.8-1.4 parts of cellulose ether, 0.6-1.2 parts of defoaming agent, and 0.2-0.8 parts of rheological agent; The amount of water used is 16% to 17.5% of the total amount of the cementitious material and auxiliary materials; The amount of anti-cracking fiber used is 5‰ to 6‰ of the total amount of gelling material, auxiliary materials and water.

3. The ultra-high compressive strength and high ductility concrete for reinforcement according to claim 2, characterized in that: The cement used is 525 cement, and the sand used is quartz sand; the dosage ratio of cement to sand is (1.16-3):1, preferably (1.45-1.85):

1.

4. The ultra-high compressive strength and high ductility concrete for reinforcement according to claim 1, characterized in that: The water reducing agent used is polycarboxylic acid water reducing agent or naphthalenesulfonate formaldehyde condensation polymer water reducing agent, and the water reduction rate is required to be 20% to 45%.

5. The ultra-high compressive strength and high ductility concrete for reinforcement according to claim 1, characterized in that: The cellulose ether is selected from methyl cellulose ether or methyl hydroxyethyl cellulose ether.

6. The ultra-high compressive strength and high ductility concrete for reinforcement according to claim 1, characterized in that: The defoaming agent is required to be suitable for high viscosity systems. After using the defoaming agent, the air content of the grouting material should be ≤3%. The defoaming agent should be a polyether defoaming agent or a fatty acid defoaming agent.

7. The ultra-high compressive strength and high ductility concrete for reinforcement according to claim 1, characterized in that: The rheological agent is a hydroxy starch ether or hydroxypropyl starch ether solution with a viscosity ranging from 1000 to 3000 mPa·s.

8. The ultra-high compressive strength and high ductility concrete for reinforcement according to claim 1, characterized in that: The anti-cracking fiber is polyethylene fiber, and the length of the polyethylene fiber is required to be 10 to 20 mm and the diameter is 50 to 100 μm.

9. The method for preparing the ultra-high compressive strength and high ductility concrete for reinforcement according to any one of claims 1 to 8, characterized in that: The other raw material components except the anti-cracking fiber are mixed according to the formula amount, and after being fully stirred, the anti-cracking fiber is added and continued to be stirred to obtain ultra-high compressive strength and high ductility concrete that can be directly used in construction.

10. The use of the ultra-high compressive strength and high ductility concrete for reinforcement as claimed in any one of claims 1 to 8, characterized in that: Used for concrete reinforcement, especially for concrete shear wall reinforcement.

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