KR102351741B1 - Additive for concrete comprising Ladle slag and, concrete composition comprising thereof, repairing method of concrete structure using the same - Google Patents

Abstract

The present invention relates to a non-shrinkage mixture containing ladle slag, a mortar composition for repairing concrete using the same, and a concrete repair method using the mortar composition for repairing concrete, the purpose of which is to recycle waste To provide a non-shrinkable mixed material containing ladle slag, which contributes to the reduction and can expect a shrinkage reduction effect even with a small amount of use, and the initial and long-term expandability is improved by the mixture consisting of the ladle slag, calcined lime and hydrofluoric anhydrite, To provide a mortar composition for repairing concrete with reduced cracking and a method for repairing concrete using the same.
The present invention relates to concrete in which a non-shrinkage mixture containing ladle slag containing 20 to 30% by weight of ladle slag powder, 20 to 36% by weight of dead burnt CaO, and 40 to 60% by weight of hydrofluoric anhydrite is added to cement. The repair mortar composition and thereby the repair of the concrete structure is made.

Description

A non-shrinkage mixture containing ladle slag, a mortar composition for concrete repair using the same, and a concrete repair method using the mortar composition for concrete repair }

The present invention relates to a non-shrinkage mixture containing ladle slag, a mortar composition for repairing concrete using the same, and a concrete repair method using the mortar composition for repairing concrete. It relates to a non-shrinkage mixture containing ladle slag capable of preventing the shrinkage and strength reduction of cement mortar by the shrinkage mixture, a cement mortar composition using the same, and a concrete repair method using the mortar composition.

In general, in concrete structures, cracks occur in the concrete due to deterioration, etc., and over time, the compressive strength of concrete and the tensile strength of reinforcing bars gradually decrease. . If the corrosion of these reinforcing bars becomes severe, the concrete structure may eventually collapse.

Accordingly, repair materials widely used for repair and reinforcement of concrete structures mainly used cement-based mortar or polymer cement mortar. Most of them focused only on improving the adhesion performance during initial construction, so there was a problem that repair work had to be done frequently because the surface was easily damaged again shortly after construction.

In addition, in order to solve the problems of the conventional concrete mortar for repair as described above, a CSA (calcium sulfoaluminate)-based expander or S-Type alumina cement-based expander is added to provide expandability, but such CSA (calcium A sulfoaluminate)-based or S-Type alumina cement-based expander has relatively good early expansion (around 28 days of age), but has a problem in that long-term expandability (after 90 days of age) has low shrinkage resistance.

In particular, CSA (calcium sulfoaluminate)-based expansion materials or S-Type alumina cement-based expansion materials have coarse rigidity, so the workability of the concrete mortar for repair is lowered, and thus there are various problems such as not being able to expect proper expandability. .

Registered Patent Publication No. 10-1398848 (2014.05.19) Registered Patent Publication No. 10-0303235 (July 10, 2001) Registered Patent Publication No. 86-001644 (October 15, 1986) Registered Patent Publication No. 10-1311720 (2013.09.17)

It is an object of the present invention to provide a non-shrinkage mixture containing ladle slag that can be expected to reduce shrinkage even with a small amount while contributing to waste reduction by recycling the steelmaking ladle slag to be disposed of.

An object of the present invention is to provide a mortar composition for repairing concrete with improved initial and long-term expandability and reduced cracking by using a mixture of ladle slag, calcined lime and hydrofluoric acid anhydrite, and a concrete repair method using the same.

The present invention relates to concrete in which a non-shrinkable mixture containing ladle slag containing 20 to 30% by weight of ladle slag powder, 20 to 36% by weight of dead burnt CaO, and 40 to 60% by weight of hydrofluoric anhydrite is added to cement. The mortar composition for repair and the repair of the concrete structure thereby are made.

The present invention is designed to have an initial expandability by ladle slag and calcified lime, ladle slag and hydrofluoric anhydrite, and a later expansibility by calcified lime and hydrofluoric acid anhydrite, so that it has an excellent expansion rate of about 1.5 times or more compared to the conventional non-shrinkable mixture. In addition, it has the effect of providing a high-quality non-shrink concrete repair mortar due to a small decrease in strength.

The present invention has the effect of having excellent workability while contributing to the reduction of waste treatment since recycling of ladle slag of 5 mm or less generated in the refining process of the steelmaking process is made.

Since the present invention has excellent expandability, there is an effect of obtaining a shrinkage reduction effect by using only about 70% of the amount of the existing non-shrinkage mixture.

Since the present invention improves the watertightness of the cured body with late-stage expandability (long-term reaction), there is an effect of improving waterproofness.

The present invention has the effect of securing high strength and high durability because the hardened body becomes dense by the ettringite reaction by ladle slag, calcined lime and hydrofluoric anhydrite.

1 is an exemplary view showing a rate of change in length according to an embodiment of the present invention;
2 is an exemplary view showing a rate of change in length according to a comparative example of the present invention;

The non-shrinkable mixture containing ladle slag according to the present invention contains 20 to 30% by weight of steelmaking ladle slag powder, 20 to 36% by weight of dead burnt CaO, and 40 to 60% by weight of hydrofluoric anhydrite.

In the non-shrinkable mixture containing ladle slag according to the present invention, the ladle slag powder and hydrofluoric anhydrite are maintained in a weight ratio of 1: 2 to 2.5, and the ladle slag and calcined lime in a weight ratio of 1:1 to 1.2 are maintained. it is preferable

That is, the non-shrinkable mixture containing ladle slag according to the present invention contains 20 to 30% by weight of steelmaking ladle slag powder, 20 to 36% by weight of dead burnt CaO, and 40 to 60% by weight of hydrofluoric anhydrite. Within the range, it is preferable that the steelmaking ladle slag powder: calcined lime: hydrofluoric anhydrite is made to have a weight ratio of 1:1 to 1.2:2.0 to 2.5.

In addition, the non-shrinkage mixture containing ladle slag according to the present invention contains 20 to 25% by weight of steelmaking ladle slag powder, 20 to 30% by weight of dead burnt CaO, and 45 to 55% by weight of hydrofluoric anhydrite. Within the range, it is most preferable that the steelmaking ladle slag powder: calcined lime: hydrofluoric anhydrite is made to have 1:1 to 1.2:2.0 to 2.5.

The ladle slag is first crushed into 4-8 mm particles by a crusher such as a jaw crusher, iron is removed by magnetic separation, and 325mesh 90% or more can pass through a crusher such as a Raymond mill on average Those pulverized so as to have a particle size of 20 µm or less are used.

계 조성을 구비하는 것으로, 분말상 래들 슬래그는 아래 [표1]에 따른 화학성분(평균 중량％)을 구비하게 된다. 이때, 나머지는 소량의 기타성분(불순물 포함)들로 이루어져 있다. Ladle slag made in this way is

By having a system composition, the powdery ladle slag has a chemical composition (average weight %) according to [Table 1] below. At this time, the rest consists of small amounts of other components (including impurities).

[Table 1]

When the ladle slag is mixed at less than 20% by weight, when etringite, which is the main reaction of the expansion reaction, is generated, the expansion amount is insufficient due to insufficient alumina source, and when it is added in excess of 30% by weight, conversely, alumina Since the excessive supply is provided to provide coarse rigidity, the coagulation reaction occurs early and workability is deteriorated, and the expansion amount is insufficient due to the early setting reaction and cracks occur, so it is added within an appropriate range.

이온에 대한 고정화가 우수하여,

이온의 용출 안정화가 우수한 특성을 구비하고 있다. In addition, the ladle slag is

Immobilization to ions is excellent,

It has excellent characteristics of stabilizing the elution of ions.

The calcified lime, also called hypocalcified lime, has a function of imparting initial expandability and late expansibility. Common quicklime or slaked lime cannot be used because a quick-setting reaction occurs when mixing with ladle slag, which inhibits the flow of mortar, so it cannot be used. When mixing with slag, the rapid setting reaction does not occur, and it has both initial expandability and late expandability, so it has a function of preventing strength reduction and expansion cracks.

The saline lime, when the content is added to less than 20% by weight, the content of the stimulant to stimulate the latent hydraulic properties of the ladle slag is insufficient, and the reactivity is lowered, which causes a phenomenon in which the initial expansion amount is insufficient. In addition, when added in an amount exceeding 36% by weight, the cured body is destroyed due to initial overexpansion, which causes a decrease in strength and expansion cracks, so it is added within an appropriate range.

The calcined lime is pulverized to 20-30 mm by a pulverizer such as a hammer crusher, calcined in a kiln such as a vertical shaft kiln at a high temperature (1250 ° C. to 1350 ° C) for 1 to 2 hours, cooled naturally, Raymond mill, etc. 200mesh, 80% of the pulverizer is pulverized to an average particle diameter of 35-45㎛ is used.

That is, conventional calcined lime is calcined at about 900 ° C. to 1,100 ° C., but conventional calcined lime calcined at such a temperature has only the initial expandability, but does not have long-term expansibility (later expansibility). As a result, a phenomenon in which the shrinkage resistance is lowered in the long term occurs.

In addition, conventional calcined lime calcined at about 900 ° C. to 1, 100 ° C. reacts with moisture in the air, resulting in a decrease in storage properties, which leads to a further decrease in post-expansion properties. It does not have early and late swells, such as scaly lime.

That is, when calcined lime calcined at about 900°C to 1,100°C is mixed with ladle slag, like general quicklime or slaked lime, a quick-setting reaction occurs and the flowability of the mortar is suppressed, thereby reducing or impossible workability. A phenomenon that causes

When the calcination temperature of the calcined lime is less than 1250° C., an exothermic reaction occurs due to a rapid reaction with water, so that the initial setting is fast, and the storage property is low, thereby inhibiting the flowability of the mortar. In addition, when the calcination temperature exceeds 1,350 °C, the reactivity is lowered and the initial expansion property is rather reduced, so that calcined at 1250 °C to 1350 °C for about 1 to 2 hours is used.

The hydrofluoric acid anhydrite is an industrial by-product, which is dried and pulverized to an average particle size of 25 to 35 μm and a moisture content of less than 5%. has the function to

의 공급원으로, 천연무수석고보다 용해도가 높아 반응성이 빠르고, 최대 팽창률에 이르는 시간이 짧으며, 적정량의 장기팽창으로 크랙발생 확률을 낮추는 기능을 구비한다. The hydrofluoric acid anhydrite is, at the time of the ettringite reaction

It has a higher solubility than natural anhydrous gypsum, so it has a faster reactivity, a shorter time to reach the maximum expansion rate, and a function of lowering the probability of cracking with an appropriate amount of long-term expansion.

That is, natural anhydrite has a low initial expansion amount due to its low solubility, which delays the time to maximum expansion, and thus the required expansion amount of the mortar is insufficient, which is not preferable in the present invention.

Since the natural anhydrite has a small initial expansion amount, in the case of a concrete repair mortar containing a natural anhydrite-containing expanding agent, the initial target expansion rate (target expansion rate within 14 days of age or 28 days of age) is met. In order to do this, a larger amount of the expanding agent containing natural anhydrite must be added. However, when a large amount of the expanding agent containing natural anhydrite is added, the long-term expansion rate becomes excessively high, resulting in expansion failure or cracks, A phenomenon in which durability may decrease may occur.

For example, in the case of a concrete repair mortar to which a 14-day target expansion rate is set to 0.4% or more, and a swelling agent containing hydrofluoric acid anhydrite and natural anhydrite in equal amounts is added, the expansion agent containing hydrofluoric acid anhydrite is added. On the other hand, when the expansion agent containing natural anhydrite is added, the expansion rate is 0.36% for 14 days and -0.01% for 28 days, whereas the expansion rate is 0.46% for 14 days and 0.01% for 28 days. do.

의 공급량이 부족하여 에트링자이트 생성이 부족하고 팽창량이 저하되며, 55중량％ 초과하여 첨가될 시, 응결이 과하게 늦어지고 과도한 장기 반응으로 인해 팽창 파괴 혹은 팽창크랙 현상이 발생되므로, 적정범위내에서 첨가된다. When the hydrofluoric acid anhydrite is added in less than 40% by weight,

Due to insufficient supply of ettringite, the formation of etringite is insufficient and the amount of expansion is reduced. When added in excess of 55% by weight, the setting is excessively delayed and expansion fractures or expansion cracks occur due to excessive long-term reaction. is added in

이온 고정화에 영향을 주지 않으면서, 높은 용해도를 통해 최대 팽창률에 이르는 시간을 단축시키고, 장기팽창으로 크랙발생 확률을 낮추는 기능을 구비한다. In addition, the hydrofluoric acid anhydrite is the

It has a function of shortening the time to reach the maximum expansion rate through high solubility without affecting ion immobilization, and lowering the probability of cracking due to long-term expansion.

이온 고정화시키는 특성을 구비하고 있으나, 천연 무수석고 또는 인산석고 등과 혼합 사용하게 될 경우, 래들 슬래그의 혼합비율이 높을 수록

이온 용출 안정화에 대한 효과가 저감되는 현상이 발생되어, 에트링자이트의 생성 시,

이온이 고정화되지 못하고 석출되는 현상(

이온의 재용출 현상))이 발생되므로, 에트링 자이트가 생성되면서,

이온의 고정화가 이루어지기 위해서는 불산 무수석고가 첨가되어야 한다. That is, the ladle slag is

It has the property of immobilizing ions, but when mixed with natural anhydrite or phosphate gypsum, the higher the mixing ratio of ladle slag, the better.

When the effect on ion elution stabilization is reduced, when etringite is generated,

A phenomenon in which ions are not immobilized and are precipitated (

ion re-elution)) occurs, and as ettringite is generated,

In order for ions to be immobilized, hydrofluoric acid anhydrite must be added.

The non-shrinkage mixture containing the ladle slag of the present invention made as described above will have the chemical components (average weight %) according to [Table 2] below. At this time, the remainder consists of a small amount of other components (including impurities).

[Table 2]

The mortar composition for repairing concrete according to the present invention is to include the non-shrinkage mixture containing the ladle slag made as described above.

As an example, the mortar composition for repairing concrete contains 10 to 15 parts by weight of a non-shrinkable mixture containing ladle slag, 100 to 300 parts by weight of silica sand, and 50 to 70 parts by weight of water, based on 100 parts by weight of cement. 5 to 10 parts by weight of powder resin, and 10 to 15 parts by weight of silica fume may be further included.

In addition, in the mortar composition for repairing concrete, various additives added to the mortar composition for repairing concrete, such as a fluidizing agent, may be further added within an appropriate range.

As such, the mortar composition for concrete repair in which the non-shrinkage mixture containing ladle slag is blended has excellent initial expansion and late expansion properties, and compared to the conventional CAS-based expansion agent or expansion agent using S-Type alumina cement, It has about 1.5 times the expandability, and through this, the phenomenon of strength deterioration is prevented.

In addition, the mortar composition for repairing concrete according to the present invention is a long-term reaction by the non-shrinkage mixture containing ladle slag, and the watertightness and waterproofness in the hardened body are improved, and the hardened body has high strength due to densification by the ettringite reaction. and high durability.

In particular, the mortar composition for repairing concrete according to the present invention, when applied to a repair method together with a reinforcing material made of steel, realizes chemical prestress, and contains a conventional CAS-based expanding agent or S-Type alumina cement-containing expanding agent. Compared to , it has the effect of being able to withstand the set load even with a small cross-sectional thickness.

In addition, the present invention can perform the repair of the concrete structure by filling the repair portion of the concrete structure damaged by deterioration and the like with the mortar composition for repairing concrete as described above. At this time, the repair site may be filled with a concrete repair mortar composition after removing the deteriorated part and then applying a concrete performance recovery agent or/and a primer, and after filling the concrete repair mortar composition, a surface coating agent may be further applied have.

Hereinafter, the present invention will be described in detail by way of Examples and Comparative Examples.

Example

After mixing ladle slag, calcined lime, and hydrofluoric acid anhydrite according to [Table 3] below to produce a non-shrinkable mixture containing ladle slag, mix the resulting non-shrinkable mixture according to [Table 4] below to obtain a specimen was formed.

The length change rate and the compressive strength change were measured by the specimen formed in this way, and the results for the length change rate are shown in [Table 5] and [Figure 1] below, and the results for the compressive strength change are shown in [Table 6] below, respectively. . At this time, as the compressive strength specimen, a 5 × 5 × 5 cm cube specimen was used, and a 4 × 4 × 16 cm specimen was used for length change rate using a micrometer.

[Table 3]

[Table 4]

[Table 5]

[Table 6]

comparative example

After mixing the CSA-based expansion material and the S-type expansion material using the S-type alumina cement at the mixing ratio shown in [Table 7] below to form a specimen, the length change rate and compressive strength thereof were measured, and the results were obtained from the sample of TEST1 of the example. In comparison with [Fig. 2], [Table 8] and [Table 9] are shown. At this time, the test method and the specimen were carried out in the same manner as in Examples.

[Table 7]

[Table 8]

[Table 9]

[Figure 2] and [Table 8] show the rate of change in length, and [Table 9] shows the rate of change in compressive strength. At the same compounding ratio, TEST 1 of the Example shows a high expansion rate and does not shrink further in the long term, so crack resistance is appeared to be high.

Although the initial expansion rate of the CSA system is lower than that of the S-Type intumescent material, the shrinkage resistance is high in the long term, but it is significantly lower than that of the inflatable material of the present invention.

The present invention is not limited to the specific preferred embodiments described above, and various modifications can be made by anyone with ordinary skill in the art to which the invention pertains without departing from the gist of the invention as claimed in the claims. Of course, such modifications are intended to be within the scope of the claims.

Claims (8)

Ladle slag powder 20 to 30% by weight, dead burnt CaO 20 to 36% by weight, hydrofluoric acid anhydrite 40 to 60% by weight,
Ladle slag powder: calcined lime: hydrofluoric acid anhydrite is made to have a weight ratio of 1:1 to 1.2: 2.0 to 2.5, and the chemical composition according to [Table 2] below (average weight %, the rest is a small amount of other components (impurities) included)), but
The ladle slag powder is pulverized to have an average particle diameter of 20 μm or less, and has a chemical composition according to [Table 1] below (average weight %, the rest is a small amount of other components (including impurities)),
The calcined lime is pulverized to 20-30 mm by a pulverizer, calcined at 1250 ° C. to 1350 ° C. for 1 to 2 hours in a kiln, cooled naturally, and then passed through a pulverizer 200 mesh, 80%, with an average particle size of 35 to 45 µm is crushed with
The hydrofluoric acid anhydrite is a non-shrinkable mixture containing ladle slag, characterized in that it is dried and pulverized to an average particle diameter of 25 to 35 μm and a moisture content of less than 5%.
[Table 1]

[Table 2]

delete delete delete A mortar composition for repairing concrete, characterized in that the non-shrinkage mixture containing the ladle slag according to claim 1 is added to the cement.
6. The method of claim 5;
The mortar composition for repairing concrete comprises 10 to 15 parts by weight of a non-shrinkable mixture containing ladle slag, 100 to 300 parts by weight of silica sand, and 50 to 70 parts by weight of water, based on 100 parts by weight of cement. mortar composition.
7. The method of claim 6;
Concrete repair mortar composition, characterized in that it further comprises 5 to 10 parts by weight of re-emulsifying powder resin and 10 to 15 parts by weight of silica fume
A concrete repair method using a mortar composition for concrete repair, characterized in that the repair portion of the concrete structure is filled with the mortar composition for concrete repair according to any one of claims 5 to 7.

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