KR101323591B1 - Concrete composition using the electric arc furnace oxidizing slag and second articles prepared with the same - Google Patents

Abstract

The present invention relates to a concrete composition using an electric furnace oxidized slag and a secondary product prepared therefrom, and more particularly to cement using an electric furnace slag coarse aggregate and fine aggregate alone or in a mixture and comprising a pozzolanic admixture. And water, to provide a concrete composition and a secondary workpiece comprising a specific stimulant in a specific content.
The concrete composition according to the present invention is suitable for use in cultverts, breakwater blocks, water pipes, etc., due to the effect of a specific stimulant, which promotes initial hardening and improves resistance to seawater and contaminated water.

Description

Concrete composition using oxidized slag of electric furnace and secondary product manufactured therefrom {CONCRETE COMPOSITION USING THE ELECTRIC ARC FURNACE OXIDIZING SLAG AND SECOND ARTICLES PREPARED WITH THE SAME}

The present invention relates to a concrete composition using an electric oxide slag and a secondary product prepared therefrom, and more particularly, to promote initial curing and to improve resistance to seawater and contaminated water, etc., and a secondary product using the same. It is about.

In general, blast furnace slag aggregates are standardized into fine aggregates and coarse aggregates for concrete. However, steel slag has been used only as a relatively low-grade civil engineering material such as road aggregates and sediments due to the volume expansion by glass lime (free calcium oxide (Free-CaO)), and has been limited to be used as concrete aggregates.

The reason why steelmaking slag is difficult to be used as aggregate for concrete is that quick slag which is not completely slag, that is, glass lime, remains in the slag formation process, and this glass lime is subsequently reacted with water to become Ca (OH) ₂ volume. It causes expansion and volume expansion causes cracking and destruction of concrete.

Among steelmaking slag, electric furnace slag is divided into electric furnace slag generated in reduction process and electric furnace oxide slag generated in oxidation process according to molten steel manufacturing process.

Of these, unlike furnace furnace slag, furnace oxide slag has low glass lime content, so there is little concern about volume expansion, so the standard has recently been enacted to be used as aggregate for concrete.

Recently, natural aggregates are gradually depleted, and thus, there are many attempts to use slag aggregates as concrete aggregates. When introducing such a prior art.

First, Japanese Laid-Open Patent Publication No. H5-279095 is used to convert the converter slag and the molten iron pretreatment slag into a concrete aggregate by blowing and spheroidizing a diameter of 5 mm or less. However, since the steelmaking slag is used only as a fine aggregate in the related art, there is a problem in that a thick aggregate is additionally added.

In addition, Japanese Laid-Open Patent Publication No. 2001-130945 is an example in which steelmaking slag is used as coarse aggregate for concrete, and concrete using aging-treated steel slag coarse aggregate and fine aggregate, blast furnace slag powder, fly ash, and silica fume is used. Manufacture. The aging treatment is intended to achieve some kind of chemical stabilization. Therefore, in order to make a good concrete in the prior art, 50% or more of the blast furnace slag fine powder, or the sum of the blast furnace slag fine powder, fly ash, silica fume mixture amount should be 50% or more. However, when the blast furnace slag fine powder is added to 50% or more as described above, there is a possibility that the initial strength is lowered, there is a problem that the working period is lowered when the mold and formwork in the actual site is used, the construction period is long.

In addition, although Japanese Laid-Open Patent Publication No. 2003-2726 uses steelmaking slag as aggregate, the molding method is a special method such as a press molding method, rather than a general concrete manufacturing method. Therefore, there is a problem in that the prior art can not make a large structure.

In addition, Japanese Laid-Open Patent Publication No. 2002-179451 uses steelmaking slag as aggregate and blast-furnace crushing slag particles are mixed by 20 to 70% to prepare concrete by the existing concrete manufacturing method. In the prior art, expansion of the furnace slag by free lime is suppressed by soluble silicic acid of the blast furnace slag. However, the amount and rate of soluble silicic acid eluted from blast furnace slag particles is much slower than the reaction of free lime reacting with water to form Ca (OH) ₂ . Therefore, there is a problem that the curing period takes a long time.

In addition, the Republic of Korea Patent No. 0592870 proposes a technology that can suppress the expansion of the converter slag and solve the problem of the initial strength by using water glass as an additive. This paper describes that when the converter slag is used as aggregate for concrete, soluble silicic acid dissociated from water glass reacts directly with Ca (OH) ₂ produced by glass lime to inhibit subsequent expansion. However, it is not related to the characteristics of the present invention, which uses the oxidized slag as coarse aggregate and fine aggregate with little expansion problem as in the present invention, and uses a specific stimulant for strengthening initial curing rate and seawater resistance.

In addition, Japanese Patent No. 3652263 relates to a hydrated hardened body using steelmaking slag, and proposes concrete that does not cause destruction by hydration reaction of free lime (CaO) during use by using converter slag. It is described that by using a silica-containing material having a hydraulic property and a silica-containing material having a pozzolanic reactivity, concrete can be produced that is not destroyed by a hydration reaction even without a blow-off treatment. However, it is not related to the characteristics of the present invention, which uses the oxidized slag as coarse aggregate and fine aggregate with little expansion problem as in the present invention, and uses a specific stimulant for strengthening initial curing rate and seawater resistance.

In addition, Japanese Patent Laid-Open No. 2002-047052 relates to a method for producing concrete, and describes a technique of manufacturing concrete using steel ash slag as coarse aggregate and fine aggregate, and using fly ash, blast furnace cement, and water. However, it is not related to the characteristics of the present invention, which uses the oxidized slag as coarse aggregate and fine aggregate with little expansion problem as in the present invention, and uses a specific stimulant for strengthening initial curing rate and seawater resistance.

In addition, Japanese Patent No. 3569656 describes a concrete composition containing steelmaking slag aggregate and capable of forming a high-strength concrete structure, and discloses a configuration including steelmaking slag aggregate, coarse aggregate and blast furnace cement, and fly ash. It is not related to the characteristics of the present invention, which uses oxidized slag as coarse aggregate and fine aggregate with little expansion problem as in the present invention, and uses a specific stimulant for strengthening initial curing rate and seawater resistance.

In addition, Japanese Patent No. 471173 relates to concrete using slag aggregates, and relates to using aggregates in which steelmaking slag and furnace crushing slag are mixed. Steelmaking slag is used as coarse aggregate and fine aggregate, and furnace slag and cement are used. Although it is characterized in that it is different from the present invention in that the furnace slag aggregate is used by mixing with the steelmaking slag aggregate, and as in the present invention, using the electric furnace oxidized slag as a coarse aggregate and fine aggregate with little expansion problem It is not relevant to the feature of the present invention to use specific stimulants for initial cure rate and seawater resistance enhancement.

The problem to be solved by the present invention is not to use the converter slag of the existing steelmaking slag as coarse aggregate and fine aggregate, but using the electric furnace oxide slag with little expansion problem due to the glass lime of steelmaking slag and its initial curing rate and It is to provide a technology that improves resistance to seawater or polluted water and secondary products using the same.

In order to achieve the above object, the present invention

It is composed of cement and water, including pozzolan-based admixtures in which electric slag coarse aggregate and fine aggregate are used alone or as a mixture, and blast furnace slag fine powder and fly ash are mixed at a ratio of 10: 1 to 0.5: 1. 0.5 to 3 parts by weight of one stimulant selected from forget-me-not (Na ₂ SO ₄ ), anhydrous gypsum (CaSO ₄ ), quicklime (CaO) and sodium hydroxide (NaOH) is added to 100 parts by weight of the cement. It provides a concrete composition to stimulate the cement containing the pozzolanic admixtures to improve the adhesion and adhesion of the coarse oxide slag and fine aggregates and the cement containing the pozzolanic admixtures to improve the initial strength of the concrete.

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In addition, it is preferable to include cement and water, including pozzolan-based admixtures, in which electric slag coarse aggregates and fine aggregates are used alone or as a mixture, and blast furnace slag fine powder and fly ash are mixed at a ratio of 10: 1 to 0.5: 1. The stimulant is selected from 100 parts by weight of cement (Na ₂ SO ₄ ), anhydrous gypsum (CaSO ₄ ), quicklime (CaO) and sodium hydroxide (NaOH) by mixing 0.5 to 3 parts by weight of one stimulant A secondary product made of a concrete composition is provided.

That is, a secondary product such as box culvert, breakwater block, tetrapod, pile, telephone pole, culvert, water pipe or retaining wall panel manufactured using the concrete composition, concrete sleeper, concrete slab track, etc. do.

Also preferably the secondary product is to be produced by the precast method.

According to the present invention can see the following effects.

First, although the blast furnace slag powder and fly ash used as the admixture in the concrete composition show the initial strength degradation of the concrete composition due to the delay in curing the initial curing, the use of the above stimulant improves the initial strength by about 5 to 10%. Indicates.

Second, when the oxidized slag fine aggregate and coarse aggregate are used in the concrete composition, it shows the stimulating effect of blast furnace slag fine powder and fly ash due to the weak alkalinity of the oxidized slag aggregate itself. In terms of initial strength than the strength used, the strength is improved by about 5 to 10%.

Third, when blast furnace slag fine powder and fly ash stimulant and electric furnace oxidized slag fine aggregate and coarse aggregate are used simultaneously in concrete composition, compared with the case of using only natural aggregate without stimulant, about 15 ~ 25% in terms of initial strength It is believed that this is due to the improvement of the physical and mechanical cohesion on the surface of the oxidized slag aggregate by electricity, as well as some of the stimulants, which stimulate the alkali component dissolution of the oxidized slag aggregate by the electricity, resulting in surface modification effect. .

Fourth, applying the above stimulating effects, physical and mechanical bonding and surface modification effects to the precast concrete composition can reduce CO ₂ generation as well as reducing energy costs by reducing the amount of steam generated to promote concrete curing. You can expect the effect.

Fifth, the concrete composition according to the present invention is a box culvert (box culvert), precast box culvert for seam tunnel, breakwater block, tetrapod (tetrapod), raft block, gravity retaining wall panel, track article (concrete sleeper, concrete slab track) Suitable for use in concrete structures, such as), using the concrete composition through the present technology can increase the common period of the concrete structure than when using a general concrete composition.

Hereinafter, the present invention will be described in more detail.

Concrete composition according to the present invention

Coarse aggregates and fine aggregates are used as electricity alone or in combination, and include cement and water containing pozzolan-based admixtures, and based on 100 parts by weight of cement, manganese (Na ₂ SO ₄ ), anhydrous gypsum (CaSO ₄ ), at least one stimulant selected from quicklime (CaO) and sodium hydroxide (NaOH) in an amount of 0.01 to 5.0 parts by weight.

In the present invention, the pozzolan-based admixture may be used at least one selected from blast furnace slag powder, fly ash and silica fume, preferably a mixture of blast furnace slag powder and fly ash may be used. At this time, the mixing ratio is not particularly limited, but blast furnace slag fine powder and fly ash may be used in a ratio of about 10: 1 to 0.5: 1. The fly ash is more preferably 5% or less of unburned carbon.

In the present invention, the stimulant not only promotes hardening of the blast furnace slag powder and fly ash, which are admixtures, but also exerts some stimulating effects on the surface of the furnace oxidized slag aggregate prepared by a slow cooling method, thereby improving the strength of concrete.

That is, in the present invention, the stimulant not only promotes hardening through chemical reactions such as blast furnace slag fine powder and fly ash, but also a fine bubble-containing electric furnace slag aggregate and hardening accelerator, which generally occur in the cooling process. Physical and mechanical bonding between the bed reaction products of the is exerted, and it also plays a role of improving the strength of the concrete by exerting some stimulating effect on the surface of the oxidized slag aggregate.

Therefore, it is possible to improve the resistance to seawater and contaminated water and at the same time to compensate for the weakness of the initial strength degradation that can be caused when using the admixture.

Such stimulant may be selected from at least one of forget-me-not (Na ₂ SO ₄ ), anhydrous gypsum (CaSO ₄ ), quicklime (CaO) and sodium hydroxide (NaOH), the amount is based on 100 parts by weight of cement It is preferable to use in the range of 0.01-5.0 weight part, More preferably, it is 0.5-3.0 weight part. If the amount of use is less than 0.01 parts by weight, the initial strength synergistic effect is insignificant. Preferably, the amount is preferably from 0.5 parts by weight to 3% by weight.

The concrete composition according to the present invention can be widely used in secondary products, such as general concrete structures, more specifically, since the specific gravity of the aggregate itself is greater (3.2 or more), it becomes buoyant because it becomes a weight than the concrete composition using only natural aggregates. It can be used in seawater structures such as box culverts, breakwater blocks, tetrapods for submerged tunnels or in submerged tunnels and in secondary products for railways or structures that require weighting.

In addition, the electric furnace oxide slag used in the present invention exhibits high compressive strength because it is harder than general natural crushed stone and has excellent wear resistance. Therefore, it may be used for piles, telephone poles, culverts or water pipes. In addition, the secondary product may be manufactured in the field, but is generally manufactured by a precast method.

Furthermore, because the blast furnace slag powder and fly ash have better chemical resistance to seawater and contaminated water than ordinary portland cement, when using concrete composition through this technology, the service life of concrete structure can be longer than that of general concrete composition. have.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

[Examples 1 to 5]

Sintered oxide slag in the furnace: coarse aggregate of oxide slag in the electric furnace: Concrete composition was blended in a weight ratio of water: cement = 1: 2.

At this time, the admixture was composed of blast furnace slag fine powder of 4,300㎠ / g powder and high quality fly ash of 3% or less of unburned carbon at a ratio of 50:40:10, respectively, in the case of Portland cement. Was used as a fine aggregate, 5 ~ 20mm was used as a coarse aggregate, the stimulant type (3% standard) and the amount of each embodiment is shown in Table 1 below.

The specimen prepared as described above was cured for 24 hours, demolded, cured in a thermostat after demolding, and measured the initial compressive strength (daily compressive strength) of concrete having a compressive strength of 30 MPa for 28 days, After curing for 28 days, the resistance of chlorine ion permeation was measured by the method of ASTM C1202-97, and the results are shown in [Table 1].

division irritant Addition amount
(Based on the mixing amount based on 100 parts by weight of cement) Average daily compressive strength (MPa) Chlorine ion penetration resistance after 28 days of curing Example 1 sulphate of soda
(Na ₂ SO ₄ ) 3% 19.62 Good Example 2 Anhydrous plaster
(CaSO ₄ ) 3% 25.07 Good Example 3 quicklime
(CaO) 3% 17.06 Good Example 4 Sodium hydroxide
(NaOH)) 3% 11.21 Good

As can be seen from the results of Table 1 above, it can be seen that for the specific stimulant according to the present invention, especially forget-me-not and anhydrous gypsum are very excellent in the initial strength.

In addition, when manufacturing concrete using an oxidized slag by electricity in comparison with the case of not using the stimulant when looking at the compressive strength and the strength expression rate when mixed with forget-me-not and gypsum as shown in Table 2 below.

division irritant Addition amount
(Based on the mixing amount based on 100 parts by weight of cement) Average daily compressive strength
(MPa) Intensity expression rate
(%) Remarks Comparative Example 1 Not added - 23.92 79.73 Comparative Example 1 sulphate of soda
(Na ₂ SO ₄ ) 3% 27.88 92.94 Best Comparative Example 1 Anhydrous plaster
(CaSO ₄ ) 3% 27.08 90.27 Great

In conclusion, according to the present invention, it was found that the forget-me-not (Na ₂ SO ₄ ) has the best initial strength expression effect.

In addition, in [Table 3] below, when compressing with mixed forget-me-not and gypsum in comparison with the case of not using a stimulant, especially based on the initial compressive strength (daily compressive strength) of concrete with 28 days design strength and 40 MPa The strength and the rate of occurrence are discussed.

division irritant Addition amount
(Based on the mixing amount based on 100 parts by weight of cement) Average daily compressive strength (MPa)
(Based on 28 days design strength 40MPa) Intensity expression rate
(%) Remarks Comparative Example 1 Not added - 29.41 73.52 Comparative Example 1 sulphate of soda
(Na ₂ SO ₄ ) 3% 35.09 87.73 Best Comparative Example 1 Anhydrous plaster
(CaSO ₄ ) 3% 31.81 79.52 Great

In addition, even when the initial compressive strength (daily compressive strength) of concrete with a design strength of 40 MPa for 28 days is used, it can be seen that the forget-me-not has the best strength expression effect in comparison with the case where no stimulant is used.

As can be seen from the results of Tables 1, 2 and 3, the concrete according to the present invention using the specific stimulant according to the present invention and using the oxidized slag as the aggregate was found to have a very large initial strength improvement effect. Able to know.

In addition, there is almost no expansion problem due to the glass lime can also be solved the problem occurred when using the conventional steelmaking slag aggregate.

As described above, the features of the present invention have been described in detail with reference to the embodiments, but the present invention can be variously modified and changed by those skilled in the art, and such variations and modifications are within the protection scope of the present invention. It should be interpreted as belonging.

Claims (5)

It is composed of cement and water, including pozzolan-based admixtures in which electric slag coarse aggregate and fine aggregate are used alone or as a mixture, and blast furnace slag fine powder and fly ash are mixed at a ratio of 10: 1 to 0.5: 1. 0.5 to 3 parts by weight of one stimulant selected from forget-me-not (Na ₂ SO ₄ ), anhydrous gypsum (CaSO ₄ ), quicklime (CaO) and sodium hydroxide (NaOH) is added to 100 parts by weight of the cement. The concrete composition, characterized in that to increase the initial strength of the concrete by increasing the adhesion and adhesion effect of the coarse oxide slag coarse aggregate and fine aggregate and the cement containing the pozzolan-based admixture by stimulating the cement containing the pozzolan-based admixture. delete It is composed of cement and water, including pozzolan-based admixtures in which electric slag coarse aggregate and fine aggregate are used alone or as a mixture, and blast furnace slag fine powder and fly ash are mixed at a ratio of 10: 1 to 0.5: 1. Prepared by mixing the stimulant selected from 0.5 to 3 parts by weight of one kind selected from forgot (Na ₂ SO ₄ ), anhydrous gypsum (CaSO ₄ ), quicklime (CaO) and sodium hydroxide (NaOH) with respect to 100 parts by weight of the cement. Secondary products. 4. The secondary product of claim 3, wherein the secondary product is a box culvert, a breakwater block, a tetrapod, a pile, a telephone pole, a culvert, a water pipe, a retaining wall panel, a concrete sleeper, a concrete slab track. Tea products. 5. The secondary product of claim 4, wherein said secondary product is made by a precast process.