A high performance concrete and a method for preparing the same

Abstract

The application discloses high-performance concrete and a preparation method thereof, and the high-performance concrete comprises the following dry materials: cement 500-700 parts, pretreated sea sand 600-700 parts, silica fume 60-80 parts, steel slag micro powder 250-350 parts, fly ash 150-180 parts, quartz sand 80-100 parts, short straight steel fiber 30-35 parts, circular ring steel fiber 20-30 parts and PVA fiber 15-17.5 parts; and the wet material comprises the following components: water 170-200 parts, water reducing agent 8-10 parts, retarder 5-7 parts and air entraining agent 1-2 parts. The pretreated sea sand is used to realize the utilization rate of the sea sand, and the addition of the steel fiber can significantly improve the tensile strength of the concrete, so that the overall mechanical properties of the concrete are improved, and the anti-corrosion capacity of the steel bars wrapped in the concrete is improved.

Description

Technical Field

[0001] This application belongs to the field of concrete technology, specifically relating to a high-performance concrete and its preparation method. Background Technology

[0002] With the continuous development of construction technology and the increasing demands on concrete performance in engineering projects, traditional concrete can no longer meet the needs of some special projects. Especially in terms of high strength, high durability, and high crack resistance, traditional concrete has significant shortcomings. Ultra-high performance concrete (UHPC), as a new type of cement-based composite material, is widely used in building components and structures with extremely high performance requirements due to its superior durability and mechanical properties.

[0003] The prior art discloses a high-strength, high-performance concrete and its preparation method; the high-strength, high-performance concrete is made from raw materials comprising the following parts by weight: cement, river sand, crushed stone, water, slag powder, fly ash, water-reducing agent, composite reinforcing fiber, magnesium sulfate, and modified calcium oxide; the modified calcium oxide is coated with a membrane; the preparation method is as follows: weigh cement, river sand, crushed stone, water, slag powder, and fly ash, mix them, and stir to obtain a premix; weigh magnesium sulfate and modified calcium oxide, mix them, and obtain a mixture; mix the premix and the mixture, add composite reinforcing fiber to obtain a mixing material, add water-reducing agent, mix, pour into a mold, and cure for 48 hours to obtain high-strength, high-performance concrete; it has the effect of avoiding cracks that are easily generated during the drying shrinkage process of high-strength, high-performance concrete.

[0004] These types of concrete often suffer from problems such as complex preparation processes, high costs, and strong dependence on raw materials. In particular, the selection and processing of aggregates is a major challenge. Traditional high-performance concrete often uses natural river sand as aggregate, but with the increasing depletion of river sand resources, finding alternative aggregates has become an urgent problem to be solved. Although sea sand is abundant, the chloride ions it contains can cause corrosion to the steel reinforcement in the concrete, thus affecting the durability of the concrete. Therefore, the application of sea sand in high-performance concrete is limited. At the same time, the chloride ions in sea sand have adverse effects on the mechanical properties of concrete, making it difficult to use sea sand in the production of high-performance concrete. Summary of the Invention

[0005] This application provides a high-performance concrete and its preparation method, aiming to solve the problem that sea sand is difficult to apply in the production of high-performance concrete in the prior art.

[0006] Firstly, a high-performance concrete includes:

[0007] Dry materials: 500-700 parts cement, 600-700 parts pretreated sea sand, 60-80 parts silica fume, 250-350 parts steel slag powder, 150-180 parts fly ash, 80-100 parts quartz sand, 30-35 parts short straight steel fiber, 20-30 parts circular steel fiber, 15-17.5 parts PVA fiber;

[0008] Short straight steel fibers have a diameter of 0.2–0.9 mm, while annular steel fibers have a circular cross-section, a length of 10–60 mm, and a diameter of 0.2–0.6 mm.

[0009] Wet mix: 170-200 parts water, 8-10 parts water-reducing agent, 5-7 parts retarder, and 1-2 parts air-entraining agent.

[0010] Furthermore, the silica fume particles have a particle size of 0.1-0.15 μm, a water requirement ratio of less than or equal to 125%, and a SiO2 content of 92-95%.

[0011] Furthermore, the chloride ion content in the pretreated sea sand is 0.1-0.7%, and the particle size of the pretreated sea sand is 0.25-0.35 mm.

[0012] Furthermore, the chloride ion content in the pretreated sea sand is 0.1-0.7%, and the particle size of the pretreated sea sand is 0.25-0.35 mm.

[0013] Furthermore, the method for preparing the pretreated sea sand includes the following steps:

[0014] Step 1: Screening: Select natural sea sand with a particle size of 0.35-0.45mm;

[0015] Step 2: Freshwater washing: Rinse the sea sand multiple times with fresh water to remove salt, organic matter and other impurities adhering to the surface of the sand grains;

[0016] Step 3: Freshwater soaking: Soak the sea sand in fresh water;

[0017] Step 4: Electrochemical desalination: Removing chloride ions from sea sand using electrodialysis;

[0018] Step 5: Drying: Dry the washed and desalinated sea sand;

[0019] Step Six: Screening and Quality Inspection: Screen the dried sea sand to select sea sand with a particle size of 0.25-0.35mm, and test the chloride ion content of the sea sand. Sea sand with a chloride ion content of 0.1-0.7% is qualified pretreated sea sand.

[0020] Furthermore, the quartz sand has a particle size of 0.5-0.6 mm and a SiO2 content greater than 95%.

[0021] Secondly, the 600-700 parts of pretreated sea sand are replaced with 350-500 parts of ceramic sand.

[0022] Furthermore, the particle size of the ceramic sand is 0.35-0.45 mm.

[0023] Thirdly, a high-performance concrete, wherein 600-700 parts of pretreated sea sand are replaced with 600-700 parts of lightweight sand, 250-350 parts of steel slag powder are replaced with 250-350 parts of iron tailings powder, 150-180 parts of fly ash are replaced with 170-200 parts, 170-200 parts of water are replaced with 200-250 parts, 8-10 parts of water-reducing agent are replaced with 10-12 parts, and the ring-shaped steel fibers and air-entraining agent are removed.

[0024] Fourthly, a method for preparing high-performance concrete includes the following steps:

[0025] S1: Dry material mixing: The dry materials are mixed evenly in proportion to form a dry mixture;

[0026] S2: Add water to the dry-mixed material, along with water-reducing agent, retarder, and air-entraining agent, and stir until well mixed.

[0027] Compared with the prior art, this application has at least the following beneficial effects:

[0028] This application utilizes pretreated sea sand to effectively reduce chloride ion content, and the addition of steel fibers significantly improves the tensile strength of concrete. The combined use of these two materials enhances the overall mechanical properties of the concrete and strengthens the corrosion resistance of the reinforcing steel bars embedded within it. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0030] Example 1:

[0031] This application provides a high-performance concrete comprising: 500-700 parts cement, 600-700 parts pretreated sea sand, 60-80 parts silica fume, 250-350 parts steel slag powder, 150-180 parts fly ash, 80-100 parts quartz sand, 170-200 parts water, 30-35 parts short straight steel fibers, 20-30 parts circular steel fibers, 15-17.5 parts PVA fiber, 8-10 parts water-reducing agent, 5-7 parts retarder, and 1-2 parts air-entraining agent.

[0032] All quantities described in this article are by weight.

[0033] Specifically, the addition of steel fibers can significantly improve the tensile strength of concrete. Because the tensile properties of steel fibers are far superior to those of ordinary concrete, when concrete is subjected to tensile forces, the steel fibers can effectively distribute the tensile force, thereby delaying or preventing cracking. Simultaneously, it can also improve the toughness of concrete. Toughness is the ability of a material to absorb energy without breaking when subjected to external forces. The addition of steel fibers allows concrete to better absorb and disperse energy when subjected to external forces such as impact or vibration, thereby improving the crack resistance and durability of concrete, and enhancing its overall performance. For example, it can improve mechanical properties such as compressive strength, flexural strength, and modulus of elasticity. Furthermore, the addition of steel fibers can also improve the workability and crack resistance of concrete, making it easier to control and manage during pouring, vibration, and curing.

[0034] Short straight steel fibers are short and straight, with a diameter generally between 0.2 and 0.9 mm. The length varies depending on specific needs and application scenarios, but it is usually not too long to maintain its uniform distribution and effective function in concrete.

[0035] The cross-section of the ring-shaped steel fiber is circular, with a length typically between 10 and 60 mm and a diameter (referring to the average or equivalent diameter of the ring) ranging from 0.2 to 0.6 mm.

[0036] High-performance concrete made from pretreated sea sand, compared to ordinary high-performance concrete, exhibits increased electrical flux with increasing chloride ion content due to the charge conduction effect of chloride salts in the sea sand. Its resistance to chloride ion penetration also improves with age and reduces corrosion of the reinforcing steel bars encased in the high-performance concrete.

[0037] By utilizing pretreated sea sand, the utilization rate of sea sand is improved, and the addition of steel fibers can significantly improve the tensile strength of concrete. When the two are used together, the overall mechanical properties of concrete are enhanced, and the corrosion resistance of the steel bars encased in the concrete is strengthened.

[0038] The silica fume particles have a particle size of 0.1-0.15 μm, a water requirement ratio of less than or equal to 125%, and a SiO2 content of 92-95%.

[0039] The chloride ion content in the pretreated sea sand is 0.1-0.7%, and the particle size of the pretreated sea sand is 0.25-0.35 mm.

[0040] The pretreatment steps for the pretreated sea sand include:

[0041] Step 1: Screening: Select natural sea sand with a particle size of 0.35-0.45mm;

[0042] Step 2: Freshwater washing: Rinse the sea sand multiple times with fresh water to remove salt, organic matter and other impurities adhering to the surface of the sand grains;

[0043] Step 3: Freshwater soaking: Soak the sea sand in fresh water;

[0044] Step 4: Electrochemical desalination: Removing chloride ions from sea sand using electrodialysis;

[0045] Step 5: Drying: Dry the washed and desalinated sea sand;

[0046] Step Six: Screening and Quality Inspection: Screen the dried sea sand to select sea sand with a particle size of 0.25-0.35mm, and test the chloride ion content of the sea sand. Sea sand with a chloride ion content of 0.1-0.7% is qualified pretreated sea sand.

[0047] The quartz sand has a particle size of 0.5-0.6 mm and a SiO2 content greater than 95%.

[0048] In one embodiment, a method for preparing high-performance concrete is provided, which, when applied to the preparation of the aforementioned high-performance concrete, includes the following steps:

[0049] S1: Dry Mixing: Cement, pretreated sea sand, silica fume, steel slag powder, fly ash, quartz sand, short straight steel fibers, circular steel fibers, and PVA fibers are mixed evenly in proportion to form a dry mixture.

[0050] S2: Add water to the dry-mixed material, along with water-reducing agent, retarder, and air-entraining agent, and stir until well mixed.

[0051] Example 2 provides a high-performance concrete comprising: 500-700 parts cement, 350-500 parts ceramsite sand, 60-80 parts silica fume, 250-350 parts steel slag powder, 150-180 parts fly ash, 80-100 parts quartz sand, 170-200 parts water, 30-35 parts short straight steel fibers, 20-30 parts circular steel fibers, 15-17.5 parts PVA fiber, 8-10 parts water-reducing agent, 5-7 parts retarder, and 1-2 parts air-entraining agent.

[0052] The particle size of the ceramic sand is 0.35-0.45mm.

[0053] In the aforementioned high-performance concrete, ceramic sand is used instead of pretreated sea sand to further improve the overall performance, but it slightly reduces the later-stage resistance to chloride ion penetration.

[0054] Example 3 provides a high-performance concrete comprising 500-700 parts cement, 600-700 parts lightweight sand, 60-80 parts silica fume, 250-350 parts iron tailings powder, 170-200 parts fly ash, 80-100 parts quartz sand, 200-250 parts water, 30-35 parts short straight steel fibers, 15-17.5 parts PVA fibers, 10-12 parts water-reducing agent, and 5-7 parts retarder.

[0055] In the aforementioned high-performance concrete, lightweight sand is used instead of pretreated sea sand. Lightweight sand has a lower density and better particle shape, which allows it to form a more uniform aggregate distribution in the concrete. The uniform aggregate distribution helps to improve the workability of the concrete, such as improving its fluidity, workability and pumpability. At the same time, it has a lower water absorption rate and better impermeability, which can effectively prevent the intrusion of water and harmful substances, thereby extending the service life of the concrete.

[0056] Therefore, compared to high-performance concrete made from pretreated sea sand, its resistance to chloride ion penetration is reduced, but its overall performance is improved.

[0057] The experimental data for Examples 1, 2, and 3 are as follows:

[0058]

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A high-performance concrete, characterized in that, include: Dry materials: 500-700 parts cement, 600-700 parts pretreated sea sand, 60-80 parts silica fume, 250-350 parts steel slag powder, 150-180 parts fly ash, 80-100 parts quartz sand, 30-35 parts short straight steel fiber, 20-30 parts circular steel fiber, 15-17.5 parts PVA fiber; The chloride ion content in the pretreated sea sand is 0.1-0.7%, and the particle size of the pretreated sea sand is 0.25-0.35 mm. The method for preparing the pretreated sea sand includes the following steps: Step 1: Screening: Select natural sea sand with a particle size of 0.35-0.45mm; Step 2: Freshwater washing: Rinse the sea sand multiple times with fresh water to remove salt, organic matter and other impurities adhering to the surface of the sand grains; Step 3: Freshwater soaking: Soak the sea sand in fresh water; Step 4: Electrochemical desalination: Removing chloride ions from sea sand using electrodialysis; Step 5: Drying: Dry the washed and desalinated sea sand; Step Six: Screening and Quality Inspection: Screen the dried sea sand to select sea sand with a particle size of 0.25-0.35mm, and test the chloride ion content of the sea sand. Sea sand with a chloride ion content of 0.1-0.7% is qualified pretreated sea sand. Short straight steel fibers have a diameter of 0.2–0.9 mm, while annular steel fibers have a circular cross-section, a length of 10–60 mm, and a diameter of 0.2–0.6 mm. Wet mix: 170-200 parts water, 8-10 parts water-reducing agent, 5-7 parts retarder, 1-2 parts air-entraining agent; All parts of the raw materials are by weight.

2. The high-performance concrete according to claim 1, characterized in that, The silica fume particles have a particle size of 0.1-0.15 μm, a water requirement ratio of less than or equal to 125%, and a SiO2 content of 92-95%.

3. The high-performance concrete according to claim 1, characterized in that, The quartz sand has a particle size of 0.5-0.6 mm and a SiO2 content greater than 95%.

4. A method for preparing high-performance concrete according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Dry material mixing: The dry materials are mixed evenly in proportion to form a dry mixture; S2: Add water to the dry-mixed material, along with water-reducing agent, retarder, and air-entraining agent, and stir until well mixed.

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