Heat-resistant high-strength high-toughness thermal-insulation functional sprayed concrete material

Abstract

The invention discloses a heat-resistant, high-strength, high-toughness and heat-insulation functional sprayed concrete material, and belongs to the technical field of concrete materials for civil engineering and hydraulic engineering, per cubic meter of the concrete material comprises 400-450 kg of a composite cementing material and 160-200 kg of water, and the water-binder ratio is 0.36-0.38; the composite cementing material comprises 70%-80% of low-heat early strength cement and 20%-30% of a TK-STZ concrete admixture; the concrete material further comprises special-shaped metal fibers, a TK-STZY super plasticizer, a JX-1 green accelerator and aggregate. Under the synergistic effect of all the materials in a certain proportion, the early strength of the concrete material is improved by 15%-20% compared with that of traditional sprayed concrete, and the later strength is 75%-85%; the material also has the advantages of higher interface bonding strength, low heat conductivity coefficient, better crack resistance and better impact toughness.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete materials for civil engineering and water conservancy engineering, and relates to a heat-resistant, high-strength, toughness, and heat-insulating functional shotcrete material. Background Art

[0002] Due to extreme climatic conditions, such as high humidity, large temperature fluctuations, and acidic gas and ion erosion, shotcrete will gradually decay or even break after a certain strength rises, with early strength increasing and later strength gradually decaying. Secondly, as climatic conditions continue to deteriorate, the interface between different materials and concrete will also be affected. When the salt contained in the rock and soil medium enters the concrete, it will have a certain impact on the interface and cause cracks or fractures between the interfaces, and continuously reduce the concrete's impermeability and toughening crack resistance. In addition, the unreasonable operation process caused by seasonal climate change is also one of the biggest reasons for the deterioration of the surrounding rock-concrete interface. Furthermore, due to the large differences in the cold winter season and summer period under this specific working condition; this will cause the part to be subjected to shear and easily cause a certain degree of impact on the sample to dissipate energy, thereby causing significant cracks or fractures on the surface of the sample.

[0003] Therefore, it is urgent to develop concrete materials that can adapt to extremely complex high-temperature environments, so as to minimize negative effects such as thermal damage, thereby ensuring the bearing capacity and reliability of concrete structures. Summary of the invention

[0004] In view of this, the present invention provides a heat-resistant, high-strength, high-toughness, and heat-insulating functional shotcrete material.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A heat-resistant, high-strength, toughness, and heat-insulating sprayed concrete material, wherein each cubic meter of the concrete material comprises: 400-450 kg of composite cementitious material and 160-200 kg of water, and the water-cement ratio is 0.36-0.38;

[0007] The composite cementitious material comprises, by mass percentage, 70% to 80% of low-heat early-strength cement and 20% to 30% of TK-STZ concrete admixture;

[0008] The above-mentioned concrete material also includes special-shaped metal fibers, TK-STZY superplasticizer, JX-1 green accelerator and aggregate. The special-shaped metal fibers are added in an amount of 0.35% to 1.0% of the volume of the concrete material, the TK-STZY superplasticizer is added in an amount of 1.0% to 2.0% of the mass of the composite cementitious material, the JX-1 green accelerator is added in an amount of 5% to 8% of the mass of the composite cementitious material, and the aggregate is added in a mass ratio of 1:3.74 between the composite cementitious material and the aggregate.

[0009] Furthermore, the above-mentioned low-heat early-strength cement has an early strength grade of 42.5R and above.

[0010] Furthermore, the TK-STZ concrete admixture has an average particle size of not more than 38 μm, a fineness of 45 μm square mesh sieve residue ≤30%, a fluidity ratio ≥95%, a chloride ion content ≤0.06%, an alkali content ≤1.5%, a moisture content ≤1.0%, a water demand ratio ≤105%, an activity index 7d ≥70%, 28d ≥70%, and a specific surface area of ​​800 to 1200 m 2 / kg.

[0011] Furthermore, the above-mentioned special-shaped metal fiber has a length of 25 to 35 mm, a diameter of 0.4 to 0.6 mm, an aspect ratio of 60, and a tensile strength of ≥1000 MPa.

[0012] Furthermore, the water reduction rate of the above-mentioned TK-STZ superplasticizer is ≥30%.

[0013] Furthermore, the JX-1 green quick-setting agent has an early 3-hour compressive strength of more than 4 MPa, and a later 1-year strength retention rate of 110%.

[0014] Furthermore, the above-mentioned aggregate includes medium sand and gravel, the mass ratio of medium sand to gravel is 903:780, the fineness modulus of medium sand is 2.5-3.0, and the sand rate is 50-55%; the gravel is crushed stone with a particle size range of 5-10mm continuous grading, the mud content is controlled within 1.8%, and the mud block content is controlled less than 0.6%.

[0015] The beneficial effects of the present invention are: (1) in an extremely hot and humid complex environment, the use of the shotcrete of the present invention can effectively optimize the early bearing performance of the structure, and the compressive strength at the ages of 3h, 8h and 28d is greater than 4MPa, 20MPa and 40MPa, respectively; in addition, the tensile strength of this type of material is also better than that of conventional shotcrete, and the bonding strength at the ages of 28d and 56d is greater than 1MPa; this can not only significantly enhance the mechanical properties of the material interface and reduce the rebound rate, but also significantly improve the construction efficiency.

[0016] (2) Compared with ordinary shotcrete, the functional shotcrete material of the present invention is suitable for extremely hot and humid complex environments. It has significant advantages in workability, crack resistance, impermeability, heat-resistant insulation effect and toughness effect; the optimization of high-position collapse resistance reaches 232.51%, the crack resistance is improved by 4 levels and there is no crack on the surface, the impermeability level reaches P12 level, the heat-resistant insulation effect is improved by 1 to 2 times compared with conventional materials, and the impact energy absorption is improved by 2 to 3 times.

[0017] The high-strength and toughness heat-insulating functional shotcrete material of the present invention has an early strength improvement of 15% to 20% and a later strength improvement of 75% to 85% compared with the traditional shotcrete under the uniform synergistic effect of various materials in a certain proportion; in addition, the material also has high interface bonding strength, low thermal conductivity, good crack resistance and excellent impact toughness. Therefore, it not only has good engineering practical value, but also can bring good economic benefits. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0019] Each cubic meter of heat-resistant, high-strength and toughness heat-insulating functional shotcrete material includes: 400-450kg of composite cementitious material and 160-200kg of water, with a water-cement ratio of 0.36-0.38;

[0020] The composite cementitious material comprises, by mass percentage: 70% to 80% of low-heat early-strength cement and 20% to 30% of TK-STZ concrete admixture;

[0021] The concrete material also includes special-shaped metal fibers, TK-STZY superplasticizer, JX-1 green accelerator and aggregates. The special-shaped metal fibers are added in an amount of 0.35% to 1.0% of the volume of the concrete material, the TK-STZY superplasticizer is added in an amount of 1.0% to 2.0% of the mass of the composite cementitious material, the JX-1 green accelerator is added in an amount of 5% to 8% of the mass of the composite cementitious material, and the aggregates are added in a mass ratio of 1:3.74 between the composite cementitious material and the aggregates.

[0022] Raw materials in the embodiments and comparative examples of the present invention: low-heat early-strength cement is 42.5R early-stage strength grade, purchased from Emei Cement Co., Ltd., Anjiang County, Sichuan Province;

[0023] TK-STZ concrete admixture, average particle size not more than 38μm, fineness (45μm square hole sieve residue) ≤30%, fluidity ratio ≥95%, chloride ion content ≤0.06%, alkali content ≤1.5%, moisture content ≤1.0%, water demand ratio ≤105%, activity index 7d ≥70%, 28d ≥70%, specific surface area 800~1200m2 / kg. It complies with the provisions of "Technical Specifications for the Application of Composite Mineral Admixtures in Concrete (DB53 / T 1043-2021)" and "Technical Specifications for the Application of Concrete Mineral Admixtures (DB11 / T 1029-2021)". Purchased from Sichuan Tieke New Building Materials Co., Ltd.;

[0024] The special-shaped metal fiber is a special-shaped steel fiber with a length of 25-35 mm, a diameter of 0.4-0.6 mm, an aspect ratio of 60, and a tensile strength of ≥1000 MPa. It was purchased from Sichuan Tieke New Building Materials Co., Ltd.

[0025] TK-STZ superplasticizer water reduction rate ≥ 30%. Purchased from Sichuan Tieke New Building Materials Co., Ltd.;

[0026] The early 3-hour compressive strength of JX-1 green accelerating agent is above 4MPa, and the strength retention rate in the later 1 year is 110%. Purchased from Sichuan Tieke New Building Materials Co., Ltd.;

[0027] River sand from Guanghan City, Sichuan Province, medium sand (Zone II sand) with fineness modulus of 2.5-3.0 and sand rate of 50-55%;

[0028] Gravel in Guanghan City, Sichuan Province, the stone is crushed stone, the particle size range is 5-10mm continuous grading, the mud content is controlled within 1.8%, and the mud block content is controlled less than 0.6%.

[0029] Example 1

[0030] The raw materials of heat-resistant, high-strength and heat-insulating shotcrete per cubic meter are as follows:

[0031] Composite cementitious materials: 450kg, including 80% low-heat early-strength cement: 360kg, 20% TK-STZ concrete admixture: 90kg;

[0032] TK-STZY superplasticizer: 9kg;

[0033] JX-1 green accelerating agent: 36kg;

[0034] Special-shaped steel fiber: 30kg;

[0035] Medium sand of machine-made sand: 903kg; sand rate 54%;

[0036] Stone: 780kg;

[0037] Water: 166.5kg.

[0038] Comparative Example 1

[0039] Compared with Example 1, no special-shaped steel fiber is added, and other raw materials and amounts remain unchanged.

[0040] Comparative Example 2

[0041] Compared with Example 1, the composite cementitious material is 450 kg, of which low-heat early-strength cement is 88.9%: 400 kg, and TK-STZ concrete admixture is 11.1%: 50 kg; other raw materials and amounts remain unchanged.

[0042] Comparative Example 3

[0043] Compared with Example 1, TK-STZY superplasticizer: 15 kg; other raw materials and amounts remain unchanged.

[0044] Comparative Example 4

[0045] Compared with Example 1, the composite cementitious material is low-heat early-strength cement: 450 kg, without adding special-shaped steel fiber; other raw materials and amounts remain unchanged.

[0046] Table 1 Raw materials and dosage of concrete materials per cubic meter in Example 1 and Comparative Examples 1-4 (unit: kg)

[0047]

[0048] Table 2 Test results of workability and thermophysical parameters of shotcrete materials in Example 1 and Comparative Examples 1-4

[0049]

[0050] Table 3 Test results of crack resistance and impermeability of shotcrete materials in Example 1 and Comparative Examples 1-4

[0051]

[0052] Table 4 Comparison of the test results of toughening and crack resistance of shotcrete materials in Example 1 and Comparative Examples 1-4

[0053]

[0054] Table 5 Test results of strength of shotcrete materials at different curing environments in Example 1 and Comparative Examples 1-4 (unit: MPa)

[0055]

[0056]

[0057] The reference standard for the test methods in Tables 2 to 5 is "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GB / T50081-2019).

[0058] The above results show that the high-strength and toughness thermal insulation functional shotcrete material of the present invention is suitable for extremely high heat and humidity environments at 28 to 95°C, and its mechanical coefficient, thermodynamic core parameters and impermeability are significantly better than traditional shotcrete, which greatly enhances the practicability and economy of this type of material, and also ensures the safety of construction, civil engineering and water conservancy construction under such specific natural conditions.

[0059] The disclosed embodiments are described to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A heat-resistant, high-strength, high-toughness, heat-insulating functional shotcrete material, characterized in that: The concrete material per cubic meter includes: 400-450 kg of composite cementitious material and 160-200 kg of water, and the water-cement ratio is 0.36-0.38; The composite cementitious material comprises, by mass percentage, 70% to 80% of low-heat early-strength cement and 20% to 30% of TK-STZ concrete admixture; The concrete material also includes special-shaped metal fibers, TK-STZY superplasticizer, JX-1 green accelerator and aggregates. The special-shaped metal fibers are added in an amount of 0.35% to 1.0% of the volume of the concrete material, the TK-STZY superplasticizer is added in an amount of 1.0% to 2.0% of the mass of the composite cementitious material, the JX-1 green accelerator is added in an amount of 5% to 8% of the mass of the composite cementitious material, and the aggregates are added in a mass ratio of the composite cementitious material to the aggregates of 1:3.

74.

2. According to claim 1, a heat-resistant, high-strength, and heat-insulating functional shotcrete material is characterized in that: The low-heat early-strength cement has an early-stage strength grade of 42.5R or above.

3. According to claim 1, a heat-resistant, high-strength, and heat-insulating functional shotcrete material is characterized in that: The TK-STZ concrete admixture has an average particle size of no more than 38 μm, a fineness of 45 μm square mesh sieve residue ≤30%, a fluidity ratio ≥95%, a chloride ion content ≤0.06%, an alkali content ≤1.5%, a moisture content ≤1.0%, a water demand ratio ≤105%, an activity index 7d ≥70%, 28d ≥70%, and a specific surface area of ​​800-1200 m 2 / kg.

4. The heat-resistant, high-strength, and heat-insulating functional shotcrete material according to claim 1, characterized in that: The special-shaped metal fiber has a length of 25 to 35 mm, a diameter of 0.4 to 0.6 mm, an aspect ratio of 60, and a tensile strength of ≥1000 MPa.

5. The heat-resistant, high-strength, high-toughness, heat-insulating functional shotcrete material according to claim 1, characterized in that: The water reduction rate of the TK-STZ superplasticizer is ≥30%.

6. The heat-resistant, high-strength, high-toughness, heat-insulating functional shotcrete material according to claim 1, characterized in that: The JX-1 green quick-setting agent has an early 3-hour compressive strength of more than 4 MPa, and a later 1-year strength retention rate of 110%.

7. The heat-resistant, high-strength, high-toughness, heat-insulating functional shotcrete material according to claim 1, characterized in that: The aggregate includes medium sand and gravel, the mass ratio of medium sand to gravel is 903:780, the fineness modulus of medium sand is 2.5-3.0, and the sand rate is 50-55%; the gravel is crushed stone with a particle size range of 5-10mm continuous grading, the mud content is controlled within 1.8%, and the mud block content is controlled less than 0.6%.

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