KR102181104B1 - Cement for hardening accelerated secondary concrete product using industrial by-products - Google Patents

Abstract

The present invention relates to a cement composition for concrete secondary products that can be economically produced using industrial by-products and hardening accelerating materials and can exhibit high compressive strength. The present invention is a cement composition for secondary concrete products, including one type of Portland cement, high powder blast furnace slag powder, cogeneration fly ash, steel quenching slag, desulfurized gypsum generated in a fluidized bed boiler combustion of petro-coke, high powder pulverized coal boiler fly ash and calcium It provides a cement composition for curing-accelerated concrete secondary products, characterized in that consisting of an aluminate compound.

Description

Cement composition for hardening accelerated secondary concrete product using industrial by-products}

The present invention relates to a cement composition for hardening-accelerated concrete secondary products using industrial by-products, and more particularly, to a concrete secondary product that can be economically produced using industrial by-products and hardening-accelerated materials and can exhibit high compressive strength. It relates to a cement composition for products.

Concrete secondary products such as piles, sewer pipes, bench flutes, etc. require high strength, and therefore, cement molded products are steam-cured or mixed with high-strength admixtures to manufacture high-strength concrete secondary products.

In addition, in order to reduce the production cost by shortening the manufacturing process, a technology for early demoulding of the cement concrete molded body is being developed, and for this purpose, the fast setting of concrete is sometimes required.

Various admixtures are used to manufacture the cement composition for secondary products of high strength and fast setting concrete, but in order to reduce the cost of cement concrete, desulfurization gypsum as an industrial by-product with Portland cement, fly ash as a byproduct of thermal power plants, and blast furnace slag fine powder. , Quenched steel slag powder, etc. are mixed and used.

Desulfurized gypsum is a by-product produced by reacting with sulfur compounds in flue gas after limestone used as desulfurization in a fluidized bed combustion furnace using petrocoke as a fuel is removed from carbon dioxide due to decarboxylation at 800~900℃ and contains a large amount of CaO. Are doing. Such desulfurized gypsum exhibits expansion characteristics by hydration reaction and can exhibit the effect of preventing cracks, so it is used as an admixture of concrete, but most of the desulfurized gypsum cannot be recycled and is being disposed of.

In addition, fly ash, an industrial by-product of thermal power plants, is now recycled as a cement raw material or concrete admixture, but a significant amount is simply landfilled and disposed of.Quick-cooled steel slag powder is a material having rapid setting and expansive properties, but most Since it is being disposed of, a plan to increase the recycling rate is urgently required.

(0001) Korean Patent Application Publication No. 10-2018-0100644 (0002) Korean Patent Application Publication No. 10-2002-0082321

In order to solve the above-described problem, the present invention utilizes industrial by-products such as pulverized coal boiler fly ash and cogeneration fly ash, desulfurized gypsum generated in a petro-coke combustion fluidized bed boiler, blast furnace slag fine powder, and rapid cooling steelmaking slag powder. It is intended to provide excellent cement compositions for concrete secondary products.

In order to solve the above-described problem, the present invention is a cement composition for a secondary concrete product, including one type of Portland cement, a high-powder blast furnace slag powder, cogeneration fly ash, steelmaking quenching slag, and desulfurization gypsum generated in a petroleum coke combustion fluidized bed boiler, It provides a cement composition for hardening-accelerated concrete secondary products, characterized in that it is composed of high-powder pulverized coal boiler fly ash and calcium aluminate compound.

The cement composition for the secondary cure-accelerated concrete product is Portland cement 1 type 34 to 47 parts by weight, high powder blast furnace slag fine powder 23 to 35 parts by weight, cogeneration fly ash 4 to 8 parts by weight, steelmaking quenching slag 1 to 8 parts by weight , 7 to 16 parts by weight of desulfurized gypsum generated in a petro-coke combustion fluidized bed boiler, 8 to 12 parts by weight of fly ash and 5 to 14 parts by weight of a calcium aluminate compound.

The high-powder blast furnace slag powder has a powderiness of 6000 to 8000 ㎠/g, the high-powder pulverized coal boiler fly ash has a powderiness of 5500 to 8500 ㎠/g, and the calcium aluminate compound has an alumina content of 50 to 58 parts by weight. I can.

The cement composition for concrete secondary products using industrial by-products according to the present invention exhibits early strength and can be demolded early after molding, thereby shortening the product manufacturing period, and having a high compressive strength for a fast time. It can be used for the production of secondary concrete products with high physical properties.

1 shows a manufacturing process diagram of a concrete secondary product according to an embodiment of the present invention.
2 shows a time-temperature condition for steam curing during the manufacturing process of a secondary concrete product according to an embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted. Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components, unless otherwise stated.

The present invention is intended to illustrate specific embodiments and to be described in detail in the detailed description, since various transformations can be applied and various embodiments can be provided. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all conversions, equivalents, or substitutes included in the spirit and scope of the present invention.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, terms such as include or have are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination of them described in the specification, and one or more other features, numbers, and steps. It is to be understood that it does not preclude the possibility of the presence or addition of, operations, components, parts, or combinations thereof.

The present invention is a cement composition for secondary concrete products, including one type of Portland cement, high powder blast furnace slag powder, cogeneration fly ash, steel quenching slag, desulfurized gypsum generated in a fluidized bed boiler combustion of petro-coke, high powder pulverized coal boiler fly ash and calcium It relates to a cement composition for curing-accelerated concrete secondary products, characterized in that consisting of an aluminate compound.

As for the Portland cement one, ordinary Portland cement used in the market may be used. This type of Portland cement is mixed with fine aggregate, coarse aggregate, and water in the secondary concrete product manufacturing process, causing a hardening reaction by hydration, maintaining the shape of the product in the initial mold and maintaining strength when transporting and moving the molded body. It can act to prevent damage, and can act to express the practical strength of the product through the curing process.

The Portland cement (type 1) is preferably mixed with 34 to 47 parts by weight with respect to the cement composition for secondary concrete products, and if the Portland cement is contained in less than 34 parts by weight, the initial hardening of the composition is delayed and the molded body is demolded. It may take a long time, and even after curing, there may be a problem that the strength of the secondary concrete product is deteriorated, and if it contains more than 47 parts by weight, the initial strength development is good and the demoulding period of the molded body can be shortened. The manufacturing cost may be high and the chemical resistance of the secondary concrete product may be deteriorated.

The high-powder blast furnace slag fine powder and the high-powder pulverized coal boiler fly ash are pozzolanic admixtures, which contribute to the improvement of long-term strength of secondary concrete products by pozzolanic reaction, and may serve to improve chemical resistance. The high-powder blast furnace slag powder and the pulverized coal boiler fly ash have a high specific surface area and can further promote pozzolanic reactivity, and chemical resistance by filling the pores of the secondary concrete product made of the cement composition for the secondary concrete product. , It can play a role in improving flame resistance. At this time, the high powder and the fine blast furnace slag powder preferably have a powder of 6000 to 8000 ㎠/g, and may include 23 to 35 parts by weight with respect to the cement composition for concrete secondary products. The high-powder pulverized coal boiler fly ash may have a powderiness of 5500 to 8500 ㎠/g, and it is preferable that 8 to 12 parts by weight of the cement composition for concrete secondary products be included. If the fine powder of the high-powder blast furnace slag and the fly ash of the high-powder pulverized coal boiler is less than the above value, the pozzolanic reactivity is lowered and the long-term strength enhancement effect is weak. This can lead to an excessive increase and worsen economics.

In addition, when the content of the blast furnace slag fine powder of the high powder is less than 23 parts by weight, the pozzolanic reactivity is low, so the long-term strength enhancement effect is small, the chemical resistance is lowered, and when it exceeds 35 parts by weight, the initial strength development is delayed and the molded body is demolded. The product manufacturing period can be lengthened because the period for the product is longer.

In addition, when the content of the high-powder pulverized boiler fly ash is less than 8 parts by weight, the long-term strength enhancement effect is small, chemical resistance is lowered, and when it is contained in excess of 12 parts by weight, the initial strength development is delayed and As the period is prolonged, the manufacturing period of the product is prolonged and the strength of the secondary concrete product may decrease.

The steel-making quenched slag is harder than general natural aggregates, has excellent wear resistance, and can exhibit high compressive strength, and thus can be used instead of aggregates. The steel-making quenched slag is composed of a combination of calcium aluminate and calcium silicate compounds, and these materials react with sulfur compounds contained in the blast furnace slag fine powder during the hydration process of the cement composition for the secondary concrete product to form calcium sulfoaluminate. It can be produced, and can function to accelerate the hardening of the cement composition by promoting the formation of etringite. It is preferable that the steel-making quenched slag contains 1 to 8 parts by weight based on the cement composition for secondary concrete products.

The cogeneration fly ash may be an industrial by-product generated from a fluidized bed combustion boiler using coal as a fuel. In commercial fluidized bed combustion boilers, limestone is used as a desulfurization agent, so CaO produced by the decarboxylation of limestone (removal of carbon dioxide) and CaSO ₄ produced by the reaction of sulfur compounds contained in coal used as a fuel exist in large quantities. It promotes hydration at the beginning of the hydration process of the cement composition for secondary products. The cogeneration fly ash preferably contains 4 to 8 parts by weight with respect to the cement composition for concrete secondary products, and when the cogeneration fly ash content is less than 4 parts by weight, the effect of promoting cement hydration may not appear, If it is included in excess of 8 parts by weight, it may have a problem of deteriorating workability due to the irregular shape of the cogeneration fly ash.

The desulfurized gypsum generated in the petro-coke combustion fluidized bed boiler may be obtained as a by-product generated after coke and limestone are burned together at 800 to 900°C in a fluidized bed combustion furnace of a fluidized bed combustion boiler using petro coke as a fuel.

Specifically, petroleum coke is used as fuel in the combustion process, limestone is used as a desulfurization agent, and CaSO ₄ is produced by reacting with CaO generated by decomposition of sulfur compounds and limestone generated in petro-coke during the combustion process, and a large amount of unreacted CaO. The mixed desulfurized gypsum that is present is generated.

The desulfurized gypsum is preferably a desulfurized gypsum composed of 62 to 69% by weight of CaO, 22 to 28% by weight of SO ₃ and 1 to 15% by weight of SiO ₂ .

The desulfurized gypsum generated in the petro-coke combustion fluidized bed boiler is rich in CaO, and the CaO can accelerate the hydration reaction of the blast furnace slag powder, and a large amount of sulfur ions are eluted due to the high solubility of SO ₃ . During the initial hydration process of cement, it can act to promote the development of initial strength by activating the formation of etringite.

Looking at the hydration acceleration reaction of the blast furnace slag fine powder by CaO of the desulfurized gypsum in detail, CaO generates calcium hydroxide during the hydration reaction, and the Ca ions of the calcium hydroxide are SiO ₂ , Al ₂ O ₃ and SiO ₂ , Al ₂ O ₃ included in the blast furnace slag fine powder. By reacting to produce calcium silicate hydrate and calcium aluminate hydrate, it exhibits an effect of enhancing strength.

It is preferable that the desulfurized gypsum contains 7 to 16 parts by weight, and when the desulfurized gypsum content is less than 7 parts by weight, the elution amount of sulfur (S) ions is small, so that ethringite contributes to the initial strength improvement in the cement hydration reaction ( 3CaO·(Al ₂ O ₃ ·3CaSO ₄ )·32H ₂ O) may not be generated smoothly, which may delay the initial strength development.If the desulfurized gypsum content exceeds 16 parts by weight, it may affect the delaying effect of setting gypsum on cement. As a result, there may be a problem that the intensity expression is delayed.

The calcium aluminate compound is preferably contained in 5 to 14 parts by weight based on the cement composition for concrete secondary products.

The calcium aluminate compound is a mixture of at least one selected from CA (CaO·Al ₂ O ₃ ), CA ₂ (CaO·2Al ₂ O ₃ ) and C ₁₂ A ₇ (12CaO·7Al ₂ O ₃ ) You can use The calcium aluminate compound is a fast-hardening admixture, of which C ₁₂ A ₇ is hydrated to generate Hydrogarnet, and reacts with gypsum to initially generate ethringite hydrate, which is cured in a short time to express strength. , It contributes to the enhancement of long-term strength by generating CSH gel in the long term.

Hydrogarnet formation reaction: C ₁₂ A ₇ + 33H ₂ O → 4C ₃ AH ₆ + 6Al(OH) ₃

Ethrinzite production reaction: C ₁₂ A ₇ + 12CaSO ₄ + 137H ₂ O

→ 4(C ₃ A 3CaSO ₄ 32H ₂ O) + 6Al(OH) ₃

When the content of the calcium aluminate compound is less than 5 parts by weight, the amount of ethringite produced in the cement composition for concrete secondary products may be insufficient, leading to a delay in initial strength development, and the content of the calcium aluminate compound If it exceeds 14 parts by weight, workability is degraded because sufficient pot life is not secured due to the rapid hydration reaction in the initial stage, and after injecting the cement composition into the mold for molding, filling is incomplete and the amount of pores generated increases. After curing, it may cause a decrease in the strength of the secondary concrete product and cause cracking.

The manufacturing process of the secondary concrete product according to the present invention is shown in FIG. 1. Figure 2 shows the steam curing conditions when steam curing after demoulding a molded body for a secondary concrete product.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement them. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or a known configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, certain features presented in the drawings are enlarged or reduced or simplified for ease of description, and the drawings and their components are not necessarily drawn to scale. However, those skilled in the art will readily understand these details.

Example 1

Table 1 below shows the composition ratios of Examples and Comparative Examples of the cement composition for a secondary concrete product according to the present invention, and Table 2 shows the results according to the Examples and Comparative Examples in Table 1. Concrete secondary products were tested according to the compressive strength test method of KS L 5105 hydraulic cement mortar.

Of the raw materials used in Examples 1 to 3 and Comparative Examples, the blast furnace slag powder was used as a powder of 6500 ㎠/g, and the fly ash for pulverized coal combustion was pulverized in a ball mill and a fly ash of 6000 ㎠/g was used. And, as the calcium aluminate compound, those having an Al ₂ O ₃ content of 51 to 55% by weight were used.

OPC blast furnace
Slag Cogeneration
Fly
Ash Steelmaking quenching
Slag Desulfurized gypsum Pulverized coal
Fly
Ash Calcium aluminate Sum Example 1 58% 20% 6% 2% 5% 8% One% 100% Example 2 54% 22% 6% 3% 6% 8% One% 100% Example 3 48% 26% 6% 4% 7% 8% One% 100% Comparative example 60% 40% - - - - - 100%

division Mouth degree Led and condensation Compressive strength (MPa) Fineness
(㎠/g) 45㎛ residue W/C Initial decision
(minute) 3 days 7 days 28 days Example 1 4,270 5.4% 28.1 260 15.2 23.1 40.4 Example 2 4,850 3.7% 27.2 280 14.7 22.6 38.9 Example 3 5,520 2.7% 27.6 310 14.1 22.2 39.4 Comparative example 3,780 7.1% 27.4 340 13.7 21.7 37.9

As shown in Table 2, it was found that the secondary concrete products according to Examples 1 to 3 had higher compressive strength than the comparative examples.

As described above, specific parts of the present invention have been described in detail, and it will be apparent to those of ordinary skill in the art that these specific techniques are only preferred embodiments, and the scope of the present invention is not limited thereby. will be. Accordingly, it will be said that the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims (3)

As a cement composition for concrete secondary products,
Portland Cement Type 1 34~47 parts by weight, high powder blast furnace slag fine powder 23~33 parts by weight, cogeneration fly ash 4~8 parts by weight, steelmaking quenching slag 1~8 parts by weight, desulfurization generated in a fluidized bed boiler with petrocoke combustion 7 to 16 parts by weight of gypsum, 8 to less than 10 parts by weight of high-powder coal boiler fly ash, and 5 to less than 10 parts by weight of a calcium aluminate compound,
The high powder and blast furnace slag fine powder has a powderiness of 6000 to 8000 cm ² /g,
The high-powder and pulverized coal boiler fly ash is a cement composition for curing-accelerated concrete secondary products, characterized in that the powder degree is 5500-8500cm ² /g. delete delete

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