Preparation method of C80 self-compacting fiber concrete based on superfine marble powder

Abstract

The invention belongs to the field of self-compacting fiber concrete, and particularly relates to a preparation method of C80 self-compacting fiber concrete based on superfine marble powder, which comprises the following steps: 1, preparing a premix comprising superfine marble powder, mineral powder, gypsum, Portland cement, water and a water reducing agent; 2, preparing fine aggregate and coarse aggregate; 3, adding the aggregate and the premix into a stirrer, performing dry stirring for 1-2 minutes, adding water, and stirring for 3-5 minutes until the materials reach a fluidized state; and 4, adding the modified steel fiber into the stirrer, and continuously stirring for 3-5 minutes to obtain the C80 self-compacting fiber concrete based on the superfine marble powder. According to the C80 self-compacting fiber concrete based on the superfine marble powder obtained by the preparation method in the scheme, the strength of concrete is improved, the brittleness of high-strength self-compacting concrete is well overcome, and the bending deformation capacity of a component made of the concrete under different use environments and load conditions is effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of self-compacting fiber concrete, and in particular relates to a method for preparing C80 self-compacting fiber concrete based on ultrafine marble powder. Background Art

[0002] At present, the definition of high-strength concrete is concrete greater than C60. Compared with conventional concrete, the advantages of high-strength concrete are mainly as follows: it can effectively reduce the size of concrete components, effectively save the amount of concrete, thereby saving raw materials and reducing energy consumption; it has good structural durability, longer service life, and low later maintenance costs. Generally speaking, the preparation of high-strength concrete usually adds many admixtures, such as silica fume and fly ash, which not only recycles waste, but also has the effect of energy saving and emission reduction. High-strength self-compacting concrete, such as self-compacting fiber concrete, combines the characteristics of high-strength concrete and self-compacting concrete, thus having significant advantages such as high strength, stable structure, good durability, and suitability for various complex projects. With the continuous improvement of the bearing capacity requirements of concrete components in tunnel engineering, marine engineering structures, large spans and super-high-rise buildings, the demand for self-compacting fiber concrete is getting higher and higher, but because traditional high-strength self-compacting concrete has the characteristics of high strength, high elastic modulus, high stiffness and small deformation, it leads to the problem of large concrete brittleness and limited ductility. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for preparing C80 self-compacting fiber concrete based on ultrafine marble powder, comprising the following steps:

[0004] Step 1: Prepare premix, which includes ultrafine marble powder, mineral powder, gypsum, silicate cement, water and water reducing agent;

[0005] Step 2: Prepare fine aggregate and coarse aggregate;

[0006] Step 3: Add aggregate and premix into the mixer, stir dry for 1-2 minutes, then add water and stir for 3-5 minutes until the material reaches a fluidized state;

[0007] Step 4: Add the modified steel fiber into the mixer and continue stirring for 3 to 5 minutes to form C80 self-compacting fiber concrete based on ultrafine marble powder.

[0008] As a preferred embodiment, the premix comprises the following components in parts by weight: 10 to 50 parts of marble powder, 10 to 50 parts of mineral powder, 5 to 15 parts of gypsum, 10 to 50 parts of Portland cement, a water-binder ratio of 0.18 to 0.22, and 1 to 5 parts of a water reducer.

[0009] As a preferred embodiment, the components of the premix are in the following parts by weight: 30 parts of marble powder, 30 parts of ore powder, 10 parts of gypsum, 30 parts of portland cement, water-cement ratio of 0.2, and 3 parts of water reducer.

[0010] As a preferred embodiment, in order to improve the water-reducing performance and reduce the cost at the same time, the water reducer is a polycarboxylate superplasticizer.

[0011] As a preferred embodiment, in order to ensure the particle uniformity of the coarse aggregate and the fine aggregate, the raw materials in step 2 are screened by a square-hole sieve to obtain fine aggregate and coarse aggregate with a preset diameter size.

[0012] As a preferred embodiment, in order to further improve the strength of the fine aggregate and the coarse aggregate and stimulate their activity, both the fine aggregate and the coarse aggregate are selected as slowly cooled slag. The particle size of the fine aggregate is 0.2 - 5 mm, and the particle size of the coarse aggregate is 5 - 16 mm; in step 2, the slowly cooled slag is first screened by particle size, and then the screened slowly cooled slag is subjected to crack detection to select the aggregate with a crack depth less than the preset value; at the same time, the slowly cooled slag aggregate is pre-wetted and saturated before mixing. The slowly cooled slag is first soaked for 24 h and then spread out and naturally air-dried to the saturated surface dry state. After the pre-wetting treatment, the water molecules inside the aggregate fill the pores, which not only improves the strength of the aggregate itself, but also avoids the structure of the gap from absorbing the water inside the paste through capillary action, ensuring the consistency of the water-cement ratio and further improving the mechanical properties of the concrete.

[0013] Preferably, the modified steel fiber in step 4 is copper-plated straight type, with a diameter of 0.2 mm, a length of 11 - 13 mm, and a tensile strength > 2300 MPa; the volume fraction is 1 - 1.3%. The preparation method of the modified steel fiber includes the following steps:

[0014] 1) Immerse the steel fiber in a dilute hydrochloric acid solution, take it out, wash it until neutral, and dry it to obtain pretreated fiber;

[0015] 2) Place the pretreated fiber prepared in step 1) in a rare earth solution, soak it for 1 - 4 h, take it out and dry it to obtain the product.

[0016] Preferably, the rare earth solution in step 2) is composed of lanthanum chloride and water in a mass ratio of (0.1 - 1.0):(90 - 110).

[0017] Preferably, after the pretreated fiber is immersed in the rare earth solution in step 2), ultrasonic oscillation is carried out for 30 - 40 min during the immersion process. The ultrasonic oscillation promotes the formation of a dense protective film on the surface of the steel fiber by the corrosion of lanthanum chloride, which not only enhances the chloride ion penetration resistance of the steel fiber itself, but also makes the bonding force between the steel fiber and the concrete stronger, enabling better stress transfer, and thus improving the overall mechanical properties of the concrete.

[0018] The preparation method provided by the present invention is simple to operate. The C80 self-compacting fiber concrete based on ultrafine marble powder prepared by it has the advantages of high strength, good workability, no noise pollution, etc., can realize rapid construction, improve construction efficiency, and reduce labor costs. In particular, in this application, by introducing ultrafine marble powder particles to fill the internal pores of the concrete, the defects in the interfacial transition zone are reduced, thereby improving the compactness and strength of the concrete, using its chemical inertness to reduce the penetration of harmful ions, and enhancing the durability; at the same time, improving the rheological properties of the concrete and reducing the risk of segregation; while the specially treated slag and modified steel fibers not only improve the strength of the concrete, but also well overcome the brittleness of high-strength self-compacting concrete, effectively improving the flexural deformation ability of the components made of concrete under different service environments and load conditions, so that it can be applied to complex structures such as long-span, heavy-load and super-high-rise buildings. Description of the Drawings

[0019] Figure 1 It is a flowchart of the preparation method of the embodiment of the present invention. Detailed Embodiments

[0020] As Figure 1 shown, it will be further described in detail below with reference to the drawings through specific embodiments:

[0021] Example 1

[0022] A preparation method of C80 self-compacting fiber concrete based on ultrafine marble powder includes the following steps:

[0023] Step 1: Prepare the premix including ultrafine marble powder, mineral powder, gypsum, portland cement, water, and water reducer. The weight parts are: 30 parts of marble powder, 30 parts of mineral powder, 10 parts of gypsum, 30 parts of portland cement, water-binder ratio of 0.20, and 3 parts of water reducer. Among them, the maximum particle size of the ultrafine marble powder is less than 50 μm, the mineral powder is S95 grade mineral powder, the portland cement is selected as P·Ⅰ42.5, the water is tap water, and the water reducer is selected as polycarboxylate high-performance water reducer.

[0024] Step 2: Prepare fine aggregate and coarse aggregate;

[0025] This step specifically includes: selecting raw materials, screening them with a square-hole sieve to obtain fine aggregate and coarse aggregate with a preset diameter size, improving the strength of the aggregate, which helps to improve the strength of the concrete. The particle size of the fine aggregate is 0.2 - 5 mm, and the particle size of the coarse aggregate is 5 - 16 mm.

[0026] Among them, the sand-binder ratio is 1.0, and the mass fraction of the coarse aggregate is 50%.

[0027] Step 3: Add the slowly cooled slag and the premix into a blender, dry mix for 1 - 2 min first, and then add water and mix for 3 - 5 min until the material reaches a fluidized state;

[0028] In this step, first screen the aggregate by particle size, and then detect the cracks of the screened aggregate, and select the aggregate with a crack depth less than the preset value. The existence of relatively deep cracks on the surface of the aggregate is likely to cause the aggregate to crack from the crack during use, affecting the particle size and strength of the aggregate. By detecting and screening the cracks of the aggregate, the strength of the aggregate is guaranteed. Before mixing, perform pre-wetting saturation treatment on the slowly cooled slag, that is, soak the slowly cooled slag for 24 h first, and then spread it out and air dry it naturally until it reaches the saturated surface dry state.

[0029] Step 4: Add steel fibers into the blender and continue to mix for 3 - 5 min to form C80 self-compacting fiber concrete based on ultrafine marble powder. The volume fraction of the steel fibers is 1.2%.

[0030] This step specifically includes:

[0031] 1): Immerse the steel fibers in dilute hydrochloric acid solution, take them out, wash until neutral, and dry to obtain pretreated fibers;

[0032] 2): Take the rare earth solution, place the pretreated fibers prepared in step 1) in the rare earth solution, soak for 2.5 h, take them out and dry to obtain. The rare earth solution is composed of lanthanum chloride and water according to the mass ratio of (0.5):(100). After the pretreated fibers are immersed in the rare earth solution, ultrasonic oscillation is carried out simultaneously for 35 min during the immersion process.

[0033] Example 2

[0034] The difference between this example and Example 1 is that in this example, the premix includes the following components: 40 parts of marble powder, 20 parts of mineral powder, 10 parts of gypsum, 30 parts of portland cement, water-binder ratio 0.20, and 3 parts of water reducer.

[0035] Example 3

[0036] The difference between this example and Example 1 is that in this example, the premix includes the following components: 20 parts of marble powder, 40 parts of mineral powder, 10 parts of gypsum, 30 parts of portland cement, water-binder ratio 0.20, and 3 parts of water reducer.

[0037] Example 4

[0038] The difference between this example and Example 1 is that in this example, the volume fraction of the steel fibers is 1.1%.

[0039] Example 5

[0040] The difference between this embodiment and Embodiment 1 is that the volume fraction of steel fiber in this embodiment is 1.3%.

[0041] Use the concrete of the above Embodiments 1-5 to prepare components. Specifically, pour the concrete into the mold, and use a vibrating rod to vibrate gently during the pouring process to eliminate air bubbles. Then, level the surface of the component. Wait for the component to stand and form, and conduct performance tests on the component after it is formed. The following standards are specifically used for performance testing:

[0042] 1. Slump and spread detection: According to GB / T 50080-2016 "Standard Test Methods for Performance of Ordinary Concrete Mixtures", detect the slump and spread of the concrete obtained in Embodiments 1-5.

[0043] 2. Concrete compressive strength test detection: Detect the concrete obtained in Embodiments 1-5 according to GB / T 50081-2009 "Standard Test Methods for Physical and Mechanical Properties of Concrete", and make the obtained concrete into cube specimens of 100mm * 100mm * 100mm.

[0044] 3. Flexural strength detection: Detect the concrete obtained in Embodiment 5 according to GB / T50081-2019 "Standard Test Methods for Physical and Mechanical Properties of Concrete", and make the obtained concrete into prism specimens of 100mm * 100mm * 400mm.

[0045] 4. Splitting tensile strength detection: Detect the concrete obtained in Embodiments 1-5 according to GB / T50081-2019 "Standard Test Methods for Physical and Mechanical Properties of Concrete", and make the obtained concrete into cube specimens of 100mm * 100mm * 100mm.

[0046] 5. Flexural toughness detection: Detect the concrete obtained in Embodiments 1-5 according to CECS13:2009 "Standard Test Methods for Fiber Reinforced Concrete", and make the obtained concrete into specimens of 100mm * 100mm * 400mm.

[0047] Table 1 shows the performance data of the above Embodiments 1-5.

[0048]

[0049] According to the performance data of Examples 1-5 in Table 1, by introducing ultra-fine marble powder particles to fill the internal pores of concrete, and at the same time using specially treated slag and modified steel fibers, the structural resistance and various mechanical properties of concrete are improved. The premix and aggregate are made of waste powder and waste slag, reducing the consumption of raw material resources by more than 30%. It is green, material-saving, and energy-saving. The high-strength concrete of this application can significantly reduce the structural section size in ultra-thin and large-span structural members, reduce the structural self-weight, and then improve the spanning ability and seismic performance of the structure, improve economic benefits, and simplify the construction process.

[0050] The above are only the embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics known in the art are not described in detail herein. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can be made. In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to explain the content of the claims.

Claims

1. A preparation method of C80 self-compacting fiber concrete based on ultra-fine marble powder, characterized in that, It includes the following steps: Step 1: Prepare the premix, which includes ultrafine marble powder, mineral powder, gypsum, portland cement, water, and water reducer; Step 2: Prepare fine aggregate and coarse aggregate; Step 3: Add the aggregate and the premix into a mixer, dry mix for 1 - 2 min first, and then add water and mix for 3 - 5 min until the material reaches the fluidized state; Step 4: Add modified steel fibers into the mixer and continue to mix for 3 - 5 min to obtain C80 self - compacting fiber concrete based on ultrafine marble powder. The modified steel fibers are prepared by the following method: 1) Immerse the steel fibers in dilute hydrochloric acid solution, take them out, wash until neutral, and dry to obtain pretreated steel fibers; 2) Place the pretreated steel fibers in lanthanum chloride aqueous solution and soak for 1 - 4 h, take them out and dry to obtain the modified steel fibers.

2. The preparation method of a C80 self-compacting fiber concrete based on ultrafine marble powder according to claim 1, characterized in that: The premix in Step 1 includes the following components in parts by weight: 10 - 50 parts of marble powder, 10 - 50 parts of mineral powder, 5 - 15 parts of gypsum, 10 - 50 parts of portland cement, water - binder ratio of 0.18 - 0.22, and 1 - 5 parts of water reducer.

3. The preparation method of a C80 self-compacting fiber concrete based on ultrafine marble powder according to claim 2, characterized in that: The premix in Step 1 includes the following components in parts by weight: 30 parts of marble powder, 30 parts of mineral powder, 10 parts of gypsum, 30 parts of portland cement, water - binder ratio of 0.2, and 3 parts of water reducer.

4. The preparation method of a C80 self-compacting fiber concrete based on ultrafine marble powder according to claim 1, characterized in that: Both the fine aggregate and the coarse aggregate in Step 2 are selected as slowly - cooled slag. The particle size of the fine aggregate is 0.2 - 5 mm, and the particle size of the coarse aggregate is 5 - 16 mm.

5. The preparation method of a C80 self-compacting fiber concrete based on ultrafine marble powder according to claim 4, characterized in that: In Step 2, first conduct particle - size screening on the slowly - cooled slag, and then conduct crack detection on the screened slowly - cooled slag, and select the aggregate with a crack depth less than the preset value.

6. The preparation method of a C80 self-compacting fiber concrete based on ultrafine marble powder according to claim 4, characterized in that: The slowly - cooled slag aggregate in Step 2 is pre - wetted and saturated before mixing. Soak the slowly - cooled slag for 24 h first, and then spread it out and air - dry naturally to the saturated surface - dry state.

7. The preparation method of a C80 self-compacting fiber concrete based on ultrafine marble powder according to claim 1, characterized in that: In Step 4, the modified steel fibers are copper - plated straight - type, with a diameter of 0.2 mm, a length of 11 - 13 mm, and a tensile strength > 2300 MPa; the volume fraction is 1 - 1.3%.

8. The preparation method of a C80 self-compacting fiber concrete based on ultrafine marble powder according to claim 1, characterized in that: The mass ratio of lanthanum chloride to water in the lanthanum chloride aqueous solution is (0.1 - 1.0):(90 - 110).

9. The preparation method of a C80 self-compacting fiber concrete based on ultra-fine marble powder according to claim 1, characterized in that: When the pretreated fibers are immersed in the lanthanum chloride aqueous solution in Step 4, ultrasonic oscillation is carried out simultaneously for 30 - 40 min.

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