High-strength and high-ductility cement-based composite material as well as preparation method and application thereof

Abstract

The invention relates to a high-strength and high-ductility cement-based composite material as well as a preparation method and application thereof. The high-strength and high-ductility cement-based composite material comprises the following components in parts by weight: 60-90 parts of cement, 10-40 parts of industrial solid waste, 20-40 parts of fine aggregate, 1-2 parts of a water reducing agent, 1-10 parts of fibers and 14-22 parts of water, the industrial solid waste comprises one or more of fly ash, silica fume, slag, steel slag and red mud; the fibers comprise one or more of polyethylene fibers, polyvinyl alcohol fibers, steel fibers, polypropylene fibers, carbon fibers, glass fibers, basalt fibers and the like; the tensile strain of the cement-based composite material is not less than 8%. Compared with the prior art, the cement-based composite material prepared by the invention has relatively high compressive strength and relatively strong deformability, and can effectively solve the problems of high brittleness, easiness in cracking, low impermeability and the like of cement concrete in a tunnel engineering lining structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and in particular relates to a high-strength and high-ductility cement-based composite material and a preparation method and application thereof. Background Art

[0002] Due to the disadvantages of traditional concrete materials such as low tensile strength, poor toughness, easy cracking and low impermeability, cracks, water seepage, poor durability and other problems often occur during tunnel operation. Concrete cracking makes it easier for corrosive media to enter the lining structure, which in turn induces steel corrosion, leading to further deterioration of the concrete structure and affecting the stability and durability of the lining structure.

[0003] Engineered Cementitious Composites have good tensile deformation and crack harmless dispersion capabilities, can effectively limit water and corrosive agents from entering the structure through the concrete surface, thereby improving the durability of the structure, and have great application prospects for solving the load-bearing and disaster prevention of tunnel engineering. CN106380147A discloses a high-temperature resistant and high-ductility fiber-reinforced cementitious composite material and a preparation method thereof. By introducing basalt fiber, the tensile strength of the final cementitious composite material is as high as 11.3MPa, and the tensile ultimate elongation is as high as 2.06%. However, the mechanical strength and tensile strain of the cementitious composite material still need to be improved to meet the application of the engineered cementitious composite material in tunnel structures.

[0004] Therefore, the mechanical properties of existing engineering cement-based composite materials need to be improved, and a new type of high-strength and high-elongation tunnel lining concrete material is urgently needed to meet the application of engineering cement-based composite materials in tunnel structures. Summary of the invention

[0005] The purpose of the present invention is to provide a high-strength and high-ductility cement-based composite material and its preparation method and application in order to overcome the defect that the mechanical properties of existing engineering cement-based composite materials used in tunnel structures need to be improved.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a high-strength and high-ductility cement-based composite material, comprising the following components in parts by weight:

[0008]

[0009]

[0010] The industrial solid waste includes one or more of fly ash, silica fume, slag, steel slag, and red mud; the fiber includes one or more of polyethylene fiber, polyvinyl alcohol fiber, steel fiber, polypropylene fiber, carbon fiber, glass fiber, basalt fiber, etc.;

[0011] The tensile strain of the cement-based composite material is not less than 8%.

[0012] Furthermore, the cement includes one or more of Portland cement and ordinary Portland cement.

[0013] Furthermore, the fine aggregate includes one or more of river sand, machine-made sand, mountain sand and artificial sand.

[0014] Furthermore, the particle size of the fine aggregate is not greater than 0.6 mm.

[0015] Furthermore, the water reducing efficiency of the water reducing agent is 24-30%.

[0016] Furthermore, the water reducer includes one or more of a polycarboxylic acid water reducer, a lignin sulfonate water reducer or a naphthalene water reducer, and is preferably a high-efficiency polycarboxylic acid water reducer.

[0017] Furthermore, the length of the fiber is 8-24 mm, and the diameter of the fiber is 20-250 mm.

[0018] Furthermore, the 28d compressive strength of the cement-based composite material is not less than 80 MPa, and the tensile strength is not less than 15 MPa.

[0019] The present invention also provides a method for preparing a high-strength and high-ductility cement-based composite material, comprising the following steps:

[0020] S1: Weigh cement, industrial solid waste, fine aggregate and water reducing agent according to weight, and stir to obtain a uniformly mixed dry powder;

[0021] S2: adding water to the dry powder and stirring to obtain a concrete matrix material;

[0022] S3: Adding fibers to the concrete matrix material and stirring evenly to obtain the high-strength and high-ductility cement-based composite material.

[0023] Furthermore, in step S1, the stirring time is 60-120s.

[0024] Furthermore, in step S2, the stirring time is 2-5 min.

[0025] Furthermore, in step S3, the stirring time is 2-5 min.

[0026] The present invention also provides an application of a high-strength and high-ductility cement-based composite material as a tunnel lining concrete material.

[0027] Due to the disadvantages of traditional concrete materials such as low tensile strength, poor toughness, easy cracking and low impermeability, tunnel lining concrete often suffers from cracks, water seepage, poor durability and other problems during operation. Concrete cracking makes it easier for corrosive media to enter the interior of the lining structure, which in turn induces steel corrosion, leading to further deterioration of the lining structure and affecting its stability and durability. Engineering cement-based composite materials have good tensile deformation and crack harmless dispersion capabilities, which can effectively limit water and corrosive agents from entering the structure through the concrete surface, thereby improving the durability of the structure. They have great application prospects in solving the load-bearing and disaster prevention of tunnel projects.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The cement-based composite material prepared by the present invention has high compressive strength and strong deformation capacity, which can effectively solve the problems of cement concrete brittleness, easy cracking and low impermeability in the lining structure of tunnel engineering, so as to improve the toughness of the tunnel structure, and has great application prospects for solving the bearing and disaster prevention of tunnel engineering.

[0030] (2) The present invention can improve the tensile strength and tensile strain of the cement-based composite material by adding reinforcing fibers to the cement-based composite material matrix, thereby improving the toughness of the tunnel lining concrete in complex environments.

[0031] (3) The present invention adds a certain weight of industrial solid waste to the concrete components, which can reduce the amount of cement used and thus reduce carbon emissions.

[0032] (4) The cement-based composite material prepared by the present invention has the characteristics of stable performance, green environmental protection and low price. It can be used as a new type of tunnel lining concrete material to effectively control problems such as cracks, water seepage and poor durability during tunnel operation, and can also reduce damage caused by disasters such as fire and earthquake. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of a uniaxial tensile specimen in the tensile test of the present invention.

[0034] Figure 2 This is a uniaxial tensile stress-strain curve of the cement-based composite material in Example 1 of the present invention.

[0035] Figure 3 This is a uniaxial tensile stress-strain curve of the cement-based composite material in Example 2 of the present invention.

[0036] Figure 4This is a uniaxial tensile stress-strain curve of the cement-based composite material in Example 3 of the present invention. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0038] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0039] The preparation method of the cement-based composite material in the following examples and comparative examples comprises the following steps:

[0040] (1) Weigh cement, industrial solid waste, fine aggregate and water reducing agent in parts by weight and stir for 90 seconds to obtain a uniformly mixed dry powder;

[0041] (2) Add water to the dry powder and continue stirring for 3 minutes to obtain a uniformly mixed viscous concrete matrix;

[0042] (3) Finally, the fibers are added into the concrete matrix and stirred for 3-5 minutes to uniformly disperse them in the matrix, thereby obtaining a uniformly mixed high-strength and high-ductility cement-based composite material.

[0043] Embodiment 1:

[0044] This embodiment provides a high-strength and high-ductility cement-based composite material, the raw material components and proportions of which are shown in Table 1:

[0045] cement Fly ash Silica Fume sand water Water reducing agent PE fiber 65 25 10 30 16 1.5 1.5

[0046] Among them, the above-mentioned cement is silicate cement with a strength grade of 52.5R; the industrial solid waste is silica fume with a silica mass percentage greater than 92% and Class F low-calcium fly ash; the fine aggregate is river sand with a particle size not exceeding 0.3mm; and the water reducer is a polycarboxylate water reducer (Sika) solid powder with a water reduction efficiency of 24-30%.

[0047] The fiber of this embodiment has a length of 18 mm, a diameter of 24 μm, a tensile strength of 2900 MPa, an elastic modulus of 116 Gpa, and a density of 0.97 g / cm 3 of polyethylene fiber.

[0048] Embodiment 2:

[0049] This embodiment provides a high-strength and high-ductility cement-based composite material, and its raw material components and proportions are shown in Table 2:

[0050] cement Silica Fume slag sand water Water reducing agent PE fiber 70 10 20 30 16 1.5 1.5

[0051] Among them, the cement is silicate cement with a strength grade of 52.5R; the industrial solid waste is silica fume and S95 slag with a silica mass percentage greater than 92%; the fine aggregate is river sand with a particle size not exceeding 0.3mm; and the water reducer is a polycarboxylate water reducer solid powder with a water reduction efficiency of 24-30%.

[0052] The fiber of this embodiment has a length of 18 mm, a diameter of 24 μm, a tensile strength of 2900 MPa, an elastic modulus of 116 Gpa, and a density of 0.97 g / cm 3 of polyethylene fiber.

[0053] Embodiment 3:

[0054] This embodiment provides a high-strength and high-ductility cement-based composite material, and its raw material components and proportions are shown in Table 3:

[0055] cement Silica Fume slag Limestone powder sand water Water reducing agent PE fiber SF Fiber 70 15 15 10 30 16 1.7 1.5 3

[0056] Among them, the above-mentioned cement is silicate cement with a strength grade of 52.5R; the industrial solid waste is silica fume with a silica mass percentage greater than 92%, S95 slag and 325 mesh limestone powder; the fine aggregate is river sand with a particle size not exceeding 0.3mm; the water reducer is a polycarboxylate water reducer solid powder with a water reduction efficiency of 24-30%.

[0057] The fibers in this embodiment include two types, one of which has a length of 18 mm, a diameter of 24 μm, a tensile strength of 2900 MPa, an elastic modulus of 116 Gpa, and a density of 0.97 g / cm 3 The other is 13mm in length, 220μm in diameter, 203Gpa in elastic modulus, 2850MPa in tensile strength, and 7.8g / cm 3 of steel fiber.

[0058] Comparative Example 1:

[0059] This comparative example is ordinary concrete.

[0060] According to the above ratio and preparation method, cubic compression specimens and "dog bone" uniaxial tension specimens with dimensions of 70.7 mm × 70.7 mm × 70.7 mm were cast (dimensions see Figure 1), placed at room temperature for 24 hours, demoulded, and then placed in a standard curing box (temperature 20±2℃, relative humidity ≥95%) for 28 days. According to GB 50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" and JC / T 2461-2018 "Test Methods for Mechanical Properties of High-Ductility Fiber-Reinforced Cement-Based Composite Materials", the compressive specimen loading rate is 2.4kN / s, and the direct tensile specimen loading rate is 2mm / min. The compressive strength, tensile strength and tensile strain of the high-strength and high-ductility tunnel lining concrete material at 28 days were measured. Among them, the tensile strength and tensile strain in Table 1 are from the attached Figure 2-4 The test results are shown in Table 4.

[0061] Table 4 Mechanical properties test results of different mix ratios at 28 days

[0062] Example 1 Example 2 Example 3 Comparative Example 1 Compressive strength MPa 95.8 91.6 98.8 30 Tensile strength MPa 19.6 19.5 21.7 3.5 Tensile strain 9.5％ 11.5％ 9.3％ 0.01％

[0063] It can be seen from the technical indicators of the above tests that, compared with Comparative Example 1, the high-strength and high-ductility cement-based composite material prepared by the present invention has both excellent 28d compressive strength (>80MPa), and excellent tensile strength (>15MPa) and tensile strain (>8%).

[0064] In summary, the polyethylene fiber and steel fiber added in the present invention can significantly improve the tensile strength and tensile strain of cement-based composite materials, and the extension effect is significantly better than that of basalt fiber, thereby improving the toughness of tunnel lining concrete in complex environments. The addition of industrial solid waste can reduce the amount of cement used, thereby reducing carbon emissions. The engineering cement-based composite material of the present invention has good tensile deformation and crack harmless dispersion capabilities, and can effectively limit water and corrosive agents from entering the interior of the structure through the concrete surface, thereby improving the durability of the structure, and has great application prospects for solving the load-bearing and disaster prevention of tunnel engineering.

[0065] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A high-strength and high-ductility cement-based composite material, characterized in that: It comprises the following components in parts by weight: The industrial solid waste includes one or more of fly ash, silica fume, slag, steel slag, and red mud; the fiber includes one or more of polyethylene fiber, polyvinyl alcohol fiber, steel fiber, polypropylene fiber, carbon fiber, glass fiber, basalt fiber, etc.; The tensile strain of the cement-based composite material is not less than 8%.

2. A high-strength and high-ductility cement-based composite material according to claim 1, characterized in that: The cement includes one or more of silicate cement and ordinary silicate cement.

3. A high-strength and high-ductility cement-based composite material according to claim 1, characterized in that: The fine aggregate includes one or more of river sand, machine-made sand, mountain sand and artificial sand.

4. A high-strength and high-ductility cement-based composite material according to claim 1, characterized in that: The particle size of the fine aggregate is not greater than 0.6 mm.

5. The high-strength and high-ductility cement-based composite material according to claim 1, characterized in that: The water reducing efficiency of the water reducing agent is 24-30%.

6. The high-strength and high-ductility cement-based composite material according to claim 1, characterized in that: The water reducer includes one or more of a polycarboxylic acid water reducer, a lignin sulfonate water reducer or a naphthalene water reducer.

7. The high-strength and high-ductility cement-based composite material according to claim 1, characterized in that: The length of the fibers is 8-24 mm.

8. The high-strength and high-ductility cement-based composite material according to claim 1, characterized in that: The 28d compressive strength of the cement-based composite material is not less than 80MPa, and the tensile strength is not less than 15MPa.

9. A method for preparing the high-strength and high-ductility cement-based composite material according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Weigh cement, industrial solid waste, fine aggregate and water reducing agent according to weight, and stir to obtain a uniformly mixed dry powder; S2: adding water to the dry powder and stirring to obtain a concrete matrix material; S3: Adding fibers to the concrete matrix material and stirring evenly to obtain the high-strength and high-ductility cement-based composite material.

10. Use of the high-strength and high-ductility cement-based composite material according to any one of claims 1 to 8 as a tunnel lining concrete material.

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