High-performance concrete and preparation method thereof

Abstract

The invention discloses high-performance concrete and a preparation method thereof. The high-performance concrete comprises the following components: dry materials: 500-700 parts of cement, 600-700 parts of pretreated sea sand, 60-80 parts of silica fume, 250-350 parts of steel slag micro powder, 150-180 parts of fly ash, 80-100 parts of quartz sand, 30-35 parts of short linear steel fibers, 20-30 parts of annular steel fibers and 15-17.5 parts of PVA fibers; wet materials: 170-200 parts of water, 8-10 parts of a water reducing agent, 5-7 parts of a retarder and 1-2 parts of an air entraining agent. The pretreated sea sand is utilized, the utilization rate of the sea sand is achieved, the tensile strength of the concrete can be remarkably improved by adding the steel fibers, after the sea sand and the steel fibers are mixed for use, the overall mechanical property of the concrete can be improved, and the corrosion resistance of reinforcing steel bars wrapped in the concrete is enhanced.

Description

Technical Field

[0001] The present application belongs to the field of concrete technology, and specifically relates to a high-performance concrete and a preparation method thereof. Background Art

[0002] With the continuous development of construction technology and the increasing requirements for concrete performance in engineering, traditional concrete can no longer meet the needs of some special projects. In particular, in terms of high strength, high durability, and high crack resistance, the performance of traditional concrete has obvious shortcomings. Ultra-high performance concrete, referred to as UHPC (Ultra-High Performance Concrete), 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 ultra-high durability and ultra-high mechanical properties.

[0003] The prior art discloses a high-strength and high-performance concrete and a preparation method thereof; the high-strength and high-performance concrete is made of the following raw materials in parts by weight: cement, river sand, crushed stone, water, slag powder, fly ash, water reducer, composite reinforcing fiber, magnesium sulfate, and modified calcium oxide; the modified calcium oxide is a layer of diaphragm coated on the surface of the calcium oxide; the preparation method thereof is: cement, river sand, crushed stone, water, slag powder, and fly ash are weighed, mixed, and stirred to obtain a premix; magnesium sulfate and modified calcium oxide are weighed, mixed, and obtained a mixture; after the premix and the mixture are mixed, composite reinforcing fiber is added to obtain a mixing material, a water reducer is added, mixed, and poured into a mold, and cured for 48 hours to obtain high-strength and high-performance concrete; the high-strength and high-performance concrete has the effect of preventing cracks from being easily generated during the shrinkage process of the high-strength and high-performance concrete.

[0004] These concretes often have problems such as complex preparation processes, high costs, and strong dependence on raw materials. In particular, in the selection and processing of aggregates, 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 in resources, the chloride ions it contains will cause corrosion to the steel bars in the concrete, thereby 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 contained in sea sand have side effects on the mechanical effects of concrete, making it difficult to use sea sand in the production of high-performance concrete. Summary of the invention

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

[0006] In a first aspect, a high performance concrete comprises:

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

[0008] Wet material: 170-200 parts of water, 8-10 parts of water reducer, 5-7 parts of retarder, 1-2 parts of air entraining agent.

[0009] 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%.

[0010] 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.

[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 method for preparing the pretreated sea sand comprises the following steps:

[0013] Step 1: Screening: Select natural sea sand with a particle size of 0.35-0.45 mm;

[0014] Step 2: Freshwater washing: Use fresh water to wash the sea sand several times to remove salt, organic matter and other impurities attached to the surface of the sand particles;

[0015] Step 3: Soak in fresh water: Soak the sea sand in fresh water;

[0016] Step 4: Electrochemical desalination: Use electrodialysis to remove chloride ions from sea sand;

[0017] Step 5: Drying: Drying the cleaned and desalted sea sand;

[0018] Step 6: Screening and quality testing: Screen the dried sea sand, select the sea sand with a particle size of 0.25-0.35mm, and test the chloride ion content of the sea sand. The sea sand with a chloride ion content of 0.1-0.7% is qualified as pre-treated sea sand.

[0019] Furthermore, the particle size of the quartz sand is 0.5-0.6 mm, and the SiO2 content is greater than 95%.

[0020] In a second aspect, 600-700 parts of the pretreated sea sand are replaced with 350-500 parts of pottery sand.

[0021] Furthermore, the particle size of the ceramic sand is 0.35-0.45 mm.

[0022] In a third aspect, a high-performance concrete is provided, wherein 600-700 parts of the pretreated sea sand are replaced with 600-700 parts of lightweight sand, 250-350 parts of the 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 reducer are replaced with 10-12 parts, and the annular steel fiber and air entraining agent are removed.

[0023] In a fourth aspect, a method for preparing high performance concrete comprises the following steps:

[0024] S1: Dry material mixing: the dry materials are mixed uniformly according to proportion to form a dry mixed material;

[0025] S2: Add water to the dry mix, add water reducer, retarder and air entraining agent at the same time, and mix well.

[0026] Compared with the prior art, this application has at least the following beneficial effects:

[0027] This application utilizes pretreated sea sand to effectively reduce the chloride ion content, and the addition of steel fiber can significantly improve the tensile strength of concrete. After the two are mixed, the overall mechanical properties of concrete can be improved, and the corrosion resistance of the steel bars wrapped in the concrete can be enhanced. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with embodiments.

[0029] Embodiment 1:

[0030] The present application provides a high-performance concrete, comprising: 500-700 parts of cement, 600-700 parts of pretreated sea sand, 60-80 parts of silica fume, 250-350 parts of steel slag powder, 150-180 parts of fly ash, 80-100 parts of quartz sand, 170-200 parts of water, 30-35 parts of short straight steel fibers, 20-30 parts of circular steel fibers, 15-17.5 parts of PVA fibers, 8-10 parts of water reducer, 5-7 parts of retarder, and 1-2 parts of air entraining agent;

[0031] All parts described in the whole text are parts by weight.

[0032] Specifically, the addition of steel fibers can significantly improve the tensile strength of concrete. Since the tensile properties of steel fibers are much better than those of ordinary concrete, when concrete is subjected to tension, steel fibers can effectively share the tension, thereby delaying or preventing the cracking of concrete, and at the same time improving the toughness of concrete. Toughness is the ability of a material to absorb energy without being damaged when subjected to external forces. The addition of steel fibers enables 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 can improve the overall performance of concrete. For example, it can improve the mechanical properties of concrete such as compressive strength, flexural strength and elastic modulus. At the same time, the addition of steel fibers can also improve the construction performance and crack resistance of concrete, making concrete easier to control and operate during pouring, vibration and maintenance;

[0033] Short straight steel fiber is a short straight steel fiber with a diameter generally between 0.2 and 0.9 mm. The length varies according to specific needs and application scenarios, but is usually not too long to maintain its uniform distribution and effective effect in concrete.

[0034] The cross section of the annular steel fiber is annular, the length is usually between 1060 mm, and the diameter (here refers to the average diameter or equivalent diameter of the annular ring) is in the range of 0.2 to 0.6 mm;

[0035] Compared with ordinary high-performance concrete, the high-performance concrete made from pretreated sea sand has a charge conduction effect of chloride salts in sea sand. The electric flux of the high-performance concrete made from pretreated sea sand increases with the increase of chloride ion content, and the chloride ion penetration resistance increases with the increase of age, and can reduce the corrosion of the steel bars wrapped in the high-performance concrete;

[0036] By using pre-treated sea sand, the utilization rate of sea sand is achieved, and the addition of steel fiber can significantly improve the tensile strength of concrete. After the two are mixed, the overall mechanical properties of concrete can be improved and the corrosion resistance of the steel bars wrapped in the concrete can be enhanced.

[0037] 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%;

[0038] The content of chloride ions 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;

[0039] The pretreatment step of the pretreated sea sand comprises:

[0040] Step 1: Screening: Select natural sea sand with a particle size of 0.35-0.45 mm;

[0041] Step 2: Freshwater washing: Use fresh water to wash the sea sand several times to remove salt, organic matter and other impurities attached to the surface of the sand particles;

[0042] Step 3: Soak in fresh water: Soak the sea sand in fresh water;

[0043] Step 4: Electrochemical desalination: Use electrodialysis to remove chloride ions from sea sand;

[0044] Step 5: Drying: Drying the cleaned and desalted sea sand;

[0045] Step 6: Screening and quality testing: Screen the dried sea sand, select the sea sand with a particle size of 0.25-0.35mm, and test the chloride ion content of the sea sand. The sea sand with a chloride ion content of 0.1-0.7% is qualified as pre-treated sea sand.

[0046] The particle size of the quartz sand is 0.5-0.6 mm, and the SiO2 content is greater than 95%;

[0047] In one embodiment, a method for preparing high performance concrete is provided, and the method is applied to the preparation of the high performance concrete, comprising the following steps:

[0048] S1: Dry material mixing: cement, pre-treated sea sand, silica fume, steel slag powder, fly ash, quartz sand, short straight steel fiber, circular steel fiber, and PVA fiber are mixed evenly in proportion to form a dry mixed material;

[0049] S2: Add water to the dry mix, add water reducer, retarder and air entraining agent at the same time, and mix well.

[0050] Embodiment 2 provides a high-performance concrete, comprising: 500-700 parts of cement, 350-500 parts of pottery sand, 60-80 parts of silica fume, 250-350 parts of steel slag powder, 150-180 parts of fly ash, 80-100 parts of quartz sand, 170-200 parts of water, 30-35 parts of short straight steel fibers, 20-30 parts of circular steel fibers, 15-17.5 parts of PVA fibers, 8-10 parts of water reducer, 5-7 parts of retarder, and 1-2 parts of air entraining agent;

[0051] The particle size of the ceramic sand is 0.35-0.45 mm.

[0052] In the above-mentioned high-performance concrete, ceramic sand is used instead of pre-treated sea sand to further improve the overall performance, but the later resistance to chloride ion penetration is reduced by a small amount.

[0053] Example 3 provides a high performance concrete, including 500-700 parts of cement, 600-700 parts of lightweight sand, 60-80 parts of silica fume, 250-350 parts of iron tailings powder, 170-200 parts of fly ash, 80-100 parts of quartz sand, 200-250 parts of water, 30-35 parts of short straight steel fibers, 15-17.5 parts of PVA fibers, 10-12 parts of water reducer, and 5-7 parts of retarder;

[0054] In the above-mentioned high-performance concrete, light sand is used instead of pre-treated sea sand, wherein the light sand has a lower density and a good particle shape, which enables it to form a more uniform aggregate distribution in the concrete. The uniform aggregate distribution helps to improve the working performance of the concrete, such as improving the fluidity, workability and pumpability of the concrete. At the same time, it has a lower water absorption rate and good anti-seepage performance, which can effectively prevent the intrusion of moisture and harmful substances, thereby extending the service life of the concrete.

[0055] Therefore, compared with high-performance concrete made from pretreated sea sand, its resistance to chloride ion penetration is reduced, but it can improve the overall performance of concrete.

[0056] The experimental data of Examples 1, 2 and 3 are as follows:

[0057]

[0058] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 of cement, 600-700 parts of pretreated sea sand, 60-80 parts of silica fume, 250-350 parts of steel slag powder, 150-180 parts of fly ash, 80-100 parts of quartz sand, 30-35 parts of short straight steel fiber, 20-30 parts of circular steel fiber, 15-17.5 parts of PVA fiber; Wet material: 170-200 parts of water, 8-10 parts of water reducer, 5-7 parts of retarder, 1-2 parts of air entraining agent.

2. A 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 content of chloride ions 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.

4. A high performance concrete according to claim 3, characterized in that: The content of chloride ions 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.

5. The high performance concrete according to claim 1, characterized in that: The preparation method of the pretreated sea sand comprises the following steps: Step 1: Screening: Select natural sea sand with a particle size of 0.35-0.45 mm; Step 2: Freshwater washing: Use fresh water to wash the sea sand several times to remove salt, organic matter and other impurities attached to the surface of the sand particles; Step 3: Soak in fresh water: Soak the sea sand in fresh water; Step 4: Electrochemical desalination: Use electrodialysis to remove chloride ions from sea sand; Step 5: Drying: Drying the cleaned and desalted sea sand; Step 6: Screening and quality testing: Screen the dried sea sand, select the sea sand with a particle size of 0.25-0.35mm, and test the chloride ion content of the sea sand. The sea sand with a chloride ion content of 0.1-0.7% is qualified as pre-treated sea sand.

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

7. The high performance concrete according to claim 1, characterized in that: 600-700 parts of the pretreated sea sand are replaced by 350-500 parts of pottery sand.

8. The high performance concrete according to claim 7, characterized in that: The particle size of the ceramic sand is 0.35-0.45 mm.

9. The high performance concrete according to claim 1, characterized in that: 600-700 parts of the pretreated sea sand are replaced with 600-700 parts of light sand, 250-350 parts of the 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 reducer are replaced with 10-12 parts, and the annular steel fiber and air entraining agent are removed.

10. A method for preparing high performance concrete according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Dry material mixing: the dry materials are mixed uniformly according to proportion to form a dry mixed material; S2: Add water to the dry mix, add water reducer, retarder and air entraining agent at the same time, and mix well.

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