KR101831827B1 - Water-resist pozzolan concrete composition - Google Patents

Abstract

The present invention relates to a crack self-repairing waterproof pozzolanic concrete composition including an amine-based rust inhibitor and a pozzolanic reactant, capable of not only reducing the occurrence element of defects after construction but also reducing the corrosion of a reinforcing rod due to an inhibitor by reducing damage due to salt and self-repairing a small scale crack. The crack self-repairing waterproof pozzolanic concrete composition including an amine-based rust inhibitor and a pozzolanic reactant according to the present invention includes 10 to 25% by weight of cement; 0.05 to 1% by weight of the amine-based rust inhibitor; 0.1 to 2.5% by weight of natural pozzolan; 28.25 to 34.84% by weight of sand; and 4.5 to 11.25% by weight of water.

Description

[0001] WATER-RESIST POZZOLAN CONCRETE COMPOSITION [0002] This invention relates to a waterproof pozzolanic concrete composition containing an amine-based rust inhibitor and a pozzolanic reaction material.

The present invention relates to a waterproof concrete composition, and more particularly, to a concrete composition capable of inhibiting the corrosion of reinforcing bars when applied to a bridge or the like, and imparting resistance to salt water such as a snow remover, thereby extending the life of the structure.

Concrete is generally made by mixing cement and aggregate and curing it. It is present in an intangible form before curing but it changes into a hard solid after curing and is a very important material for our life. All the general characteristics of concrete are determined by cement, and the determination of the physical properties such as compression resistance, tensile strength and absorption tendency depends on cement.

Cement is a compound composed of calcium, silica, and alumina. It reacts with water to have a certain amount of bonding water, which is cured. The broad cement is an amorphous phase, but it refers to any substance that changes into an irreversible shaped object after a certain condition. The material used for the dentistry may also be called cement, but the common cement is portland cement. In ancient Egypt, it was used to build buildings using ash and calcium hydroxide. In Europe, plaster was used for interior decorations, but all of them are included in the scope of cement.

Pozzolan is a substance that does not cure itself but slowly solidifies in a specific atmosphere such as alkali. Its classification is classified into natural pozzolan and artificial pozzolana. Fly ash and slag generated from steel mills are typical examples of artificial pozzolans, as lightweight materials collected and scattered among the burned materials generated from thermal power plants are called slag. Natural pozzolan is represented by volcanic ash and structural soot. The reaction mechanism is the same for both artificial pozzolan and natural pozzolan, and soluble calcium hydroxide proceeds to a path that is eroded and fixed after slowly corroding silica contained in pozzolan.

Since the pozzolanic reaction proceeds slowly, it decreases the size of the concrete capillary when it is included in the concrete production, and the decrease of the capillary is generally decreased after 14 days of the concrete production and the pozzolanic reaction occurs after that, The absorption capacity for absorbing moisture is remarkably reduced. Concrete using such a reaction is excellent in flame retardancy and corrosion resistance, but may cause rapid neutralization due to carbonation. This is because the silica and the calcium hydroxide contained in the concrete reduce the function of controlling the pH of the concrete.

Generally, the amount of pozzolan in the weight of cement used in concrete can be used up to about 10 to 60%. When the amount of pozzolan used does not exceed a certain amount, the capillary in the concrete can not be filled, Is difficult to achieve. In addition, the decrease in pH affects the corrosion behavior of reinforcing bars in concrete. Generally, corrosion of reinforcing bars forms passive by alkali at pH 10 or higher and no further corrosion occurs. On the other hand, when the pH is lower than 10, rust easily occurs and the generated rust generates a high volume expansion pressure, which causes cracks to easily occur in the portion where the reinforcing bars are used.

Therefore, when pozzolan is used for concrete, the ratio of water to cement must be strictly observed and it needs to be supplemented. Particularly, when pozzolan is used, the workability is changed by time due to the absorption of porous pozzolan. Therefore, there is a tendency that the workability is frequently changed, and the workability is not changed. The proposal is very urgent. In addition, since the cracks are self-healed and the corrosion caused by the water absorbed and absorbed by the cracks has the greatest influence, the concrete giving the self-healing function is considered to have a very good effect on the durability enhancement of the future structures.

The volcanic ash is a very useful substance as a pozzolanic material, and the characteristics of the volcanic ash are as shown in the SEM photograph of FIG. 1 (right side of FIG. 1). Compared to artificial pozzolans such as fly ash (left side of Fig. 1) and slag in artificial pozzolans, natural pozzolans have a large difference in composition depending on the region and the like. Figure 2 shows the physical and chemical differences of fly ash, slag and ash. At present, most of the pozzolanic materials in Korea are artificial pozzolans. Natural pozzolans are used in a limited manner. Particularly, they are very fine powders. When applied to concrete, they absorb a large amount of water to increase the ratio of water and cement in concrete. Therefore, the change in workability at the beginning and during the work can greatly affect the quality of the concrete because the workability changes greatly during the time that the concrete is not cured, that is, the workable time, and the high water and cement ratio is the durability .

For this reason, artificial pozzolans are generally used rather than natural pozzolans, but natural pozzolans are advantageous for the purpose of rapidly improving the strength of concrete with quick reactivity. However, in the case of natural pozzolan, the composition of the natural pozzolan varies greatly depending on the mountain area. Therefore, caution is required when using it. Especially, the specific surface area greatly affects the workability, so more care must be taken.

The present invention is characterized in that a water repellent property is imparted by using a pozzolanic reaction and a rustproofing agent is introduced into the concrete to form an anti-rust concrete. Unlike conventional nitrite-based rust inhibitor or capsule-type rust inhibitor, the self-rusting property is firstly required to seal the cracks by self-healing when cracks occur. At this time, the rust inhibitor contained in the concrete is attached to the leaked reinforcing bar to prevent rust Should be able to. The ferrocyclic iron is generated very rapidly by the contact with water in which oxygen exists, and in particular, when there is chloride ion, rust occurs immediately.

This is caused by the electron transfer between the ions. In order to inhibit it, there is a small model which directly acts on the rust like nitrite and zinc, and can be classified into the atmosphere type which does not act directly on the generated rust. In general, the more difficult technique is to convert the resulting rust into passive rust. Reinforcement in concrete is greatly influenced by the atmosphere. According to reports, the pH of the concrete affects the corrosion amount after immersion as shown in Table 1 below.

[Relationship between pH and corrosion amount of reinforcing steel]

Especially, when the pH is lower than 11, the amount of corrosion increases to 1.80, which is about 9 times as high as 0.02% of pH 12. Compared to 12 when the pH is 11, even if it is enclosed, it increases by 5 times and increases to 0.1% at pH 11. Therefore, concrete must maintain abundant alkalinity. If sufficient alkalinity is not maintained, the concrete can be prevented from corrosion by reinforcing the degree of sealing by increasing the degree of alkalinity in the capillary or by using a rustproofing agent in the capillary by providing waterproofing by an auxiliary means.

The reason for this is the origin of the introduction of a very important rustproofing principle. In the present invention, crack generation is analyzed as the most important cause of rust. When cracks are generated, as described above, by forming an open atmosphere, The mechanism of increasing the pH in the cracks at the same time and acting on the corrosion inhibitor was constructed.

Therefore, in the case of cracks, a large amount of calcium hydroxide, which can heal the cracks, is first eluted and ettringite (hydrated sulfate of calcium and aluminum) is deposited on the cracks and calcium-silica crystals accumulate in the cracks A system is constructed which seals the cracks, acts as a step in which the high pH and the corrosion inhibitor are eluted inside the sealed cracks. However, since these reactions do not occur sequentially, both reactions occur at the same time, but the corrosion inhibitor is considered to be slower than the formation reaction of ettringite due to its strong adsorption ability with cement.

According to the present invention, a large amount of ettringite compound accumulates in the interior of the crack after sealing the crack, and the accumulated compound is converted into calcium-silica filament to sufficiently fill the crack and maintain a high pH Make the mood as possible. In addition, the corrosion inhibitor is confined to prevent the corrosion of the reinforcing bars at the same time. In order for this series of reactions to take place, a large amount of amorphous silica, which can be self-healing and rustproofing agents, and sufficiently water-tight to fill the voids, must be present before a series of reactions can occur.

The present invention can suppress the corrosion of reinforcing steel due to cracks generated more completely than the above-mentioned conventional techniques, and does not cause degradation of compressive strength even when immersed in water without using polymers or the like, It is very advantageous to ultimately block the deterioration due to chemical reaction such as snow remover and to prevent the damage caused by the cracks. The amine-based rustproofing agent and the crack-resistant self-repairing waterproof pozzolanic concrete composition containing the pozzolan- The purpose is to provide.

In order to solve the above-mentioned problem, a material which can heal cracks should be used first. The self-healing substances known in the past include microbial application technology, microcapsule application technology, and infiltration technology, but the quickest and easiest way to heal is using inflatable materials. This is very useful, but there is a disadvantage in that the continuous supply of sulphate or the excessive amount of free calcium hydroxide in the concrete can cause excessive expansion and collapse.

In order to prevent such disadvantages, an expandable self-healing substance within the reference volume must be used, and a substance capable of lowering the absorption ratio must be present in order to prevent the continuous invasion of water. Therefore, the expansive substance which acts as self-healing substance uses Calcium sulfur aluminate (CSA) and its reaction occurs immediately after contact with water. To prevent this, the surface should be coated with fatty acid.

The CSA coated with fatty acid reacts with the calcium hydroxide due to the reaction of cement in the concrete when it is released into water to convert it into insoluble salt, thereby opening the coating film, reacting with the water absorbed at the time of cracking and excess calcium hydroxide, Thereby making it possible to seal the cracks. This method has already been proved and is being used as self-healing concrete.

However, this self-healing process has a low permeability ratio when the swelling agent is excessively used or when the water cement ratio is very high, and the low permeability ratio continuously supplies water and calcium hydroxide to continuously produce the etringing compound, Thereby generating an expansion pressure due to the accumulation of ettringite inside. If the expansion pressure is constantly increased, it will result in collapse of SH gel, which is the main bond of cement, resulting in a bad result of concrete collapse rather than cracking. Therefore, they should be installed in a proper blocking wall to block the required amount of water .

The blocking wall is more effective than the inorganic material such as polymer, and the aluminum silicate in the clay is preferable as the impregnating agent. Natural pozzolans are also very useful as such pozzolans and prevent water migration in unhardened concrete to prevent segregation of cement, sand and gravel, as well as to prevent migration of rust inhibitors by the lattice. In addition, when the rust inhibitor is adsorbed in the pores and the self-repair agent moves to the cracks when cracks are generated, a certain amount of rust inhibitor concentration is maintained in the cracks, and when the environment in which the rust of the reinforcing bars caused by the brine or water is made is strongly adsorbed, It acts to inhibit the occurrence. As rust inhibitor, amine-based rust inhibitor is more useful than nitrite-based rust inhibitor.

In the case of nitrite corrosion inhibitor, iron nitrite is consumed, iron hydroxide forms iron oxide to form a passive film, but in the case of amine corrosion inhibitor, it is strongly adsorbed on metal surface to prevent oxygen binding, It is possible to form a sufficient film for preventing corrosion. In addition, nitrite is a material that induces very fast reactivity with cement. Therefore, it has a disadvantage that ratio of water and cement of concrete should be considered when using.

The present invention has been completed based on the concept that the pozzolan, the rust inhibitor, and the self-healing material are used for forming a concrete, and it is difficult to obtain both a self-maintaining property, a rustproof property and a waterproof property. We are confident that the durability can be greatly increased. The details will be described in detail through examples.

The concrete pavement method including the rust preventive agent and the self-repairing material according to the present invention reduces the damage caused by the salt, which is frequently damaged recently, and self-repair the small scale crack that can not occur during construction, It is anticipated that it will be possible to obtain enormous economic effect by reducing the corrosion of steel by the rust preventive agent and increasing the service life.

FIG. 1 is a SEM photograph of a fly ash as an artificial pozzolan and a volcanic acid as a natural pozzolan;
FIG. 2 is a physical and chemical property comparison chart of the artificial pozzolanic fly ash, slag and natural pozzolanic volcanic agent.

Hereinafter, embodiments of the present invention will be described in detail. Constitution of material to complete the present invention As the binder of the material, ordinary cement and ultra fast cement can be used as cement. In general, cement is used in the new process requiring a slow curing reaction. In case of ultra fast cement, it can be used in the repair process where rapid curing is required. The amount of cement is generally specified to be 1 m ³ , and the amount used for the present invention is 10 to 25 wt%. When it is smaller than 10% by weight, it is difficult to obtain a predetermined compressive strength characteristic. When it is larger than 25% by weight, a large amount of cracks may occur because the reaction heat amount is too large. Their preferred amount is 12 to 20% by weight.

The rustproofing agent for rust prevention is preferably powdered as an amine-based rust inhibitor. In case of liquid phase, it should be mixed with a chemical admixture for concrete. It can be used in concrete production, but it is more preferable to include powdered material in the construction of cement desirable. This is because when the liquid phase is used, the mixing time in the concrete production is very short as 45 seconds, so that the complete mixing may not be performed. It may be used as a liquid phase but it may change the workability of concrete during use. Should be used afterwards.

The amount of the amine-based rust inhibitor may be 0.05 to 1% by weight. If the non-amine type nitrite type is used, it is preferable to use 2 to 4 times as much as the use amount, and it is preferable not to use it because it may affect the workability and the setting time. If the amount of the rust inhibitor is less than 0.05% by weight, sufficient adsorption to the reinforcing bar does not occur and it is difficult to obtain the desired rust-preventive characteristics. If the amount exceeds 1% by weight, the used amine may be leached out of the concrete. A preferable amount of the rust inhibitor to be used is 0.1 to 0.5 wt%.

Concrete watertightness and prevention of leakage of rust preventive agent should be used as natural pozzolan. In case of artificial pozzolan, as shown in Fig. 1, there is no place to physically adsorb rust preventive agent, The natural pozzolanic acid or diatomaceous earth having a large amount of pores should be used as shown in Fig.

When the amount of the natural pozzolan is less than 0.1% by weight, the amount of the rust inhibitor adsorbed and the effect of filling the capillary are so small that the rust inhibitor may leak out. When the use amount of the natural pozzolan is more than 2.5% by weight, It is undesirable because it can have a bad influence. The preferred amount of pozzolan used is from 0.2 to 1.5% by weight.

Also, pozzolan is a very important material for the present invention and should have a specific surface area of 1,500 to 200,000 cm ² / g. Ten thousand and one 1,500cm ² / g than when there is little corrosion inhibitor in the concrete of the water flow that the uncured state by increasing generation of cement between the grid by the suction effect and charging effect can be leaked to reap the desired effect difficult 200,000cm ² / g It is difficult to handle because the amount of scattering is too large. The preferred specific surface area of natural pozzolans is 2,000 to 150,000 cm ² / g.

Aggregates are not specially specified and generally used sand and gravel should be used, but sand should not be used. The amount of sand used is 28.25 to 34.84% by weight of the total weight, and the weight of the coarse aggregate is 30 to 40% by weight. However, the amount of sand and coarse aggregate can be determined according to the standard specification guidelines in consideration of workability.

The self-repairing substance includes calcium sulfo-aluminate, and 0.5 to 2% by weight may be used. If the self-repairing material is less than 0.5%, self-conservativeness is low. If cracking occurs, there is insufficient crack filling for sealing. If it is more than 2%, excessive pressure may be generated in the filling part.

In addition, 4.5 ~ 11.25% of water is used. If it is less than 4.5, workability is poor and it is difficult to use. If it exceeds 11.25%, the compressive strength may be lowered. However, the amount of water may vary depending on the weight of the cement. It should be selected considering the workability and resistance to compressive strength. If it exceeds 60% of the cement weight, it should not be used because it may cause a sharp decrease in compressive strength.

Meanwhile, the crack-resistant self-repairing waterproof pozzolanic concrete composition containing the amine-based rust inhibitor and the pozzolanic reaction material according to the present invention may contain 3 to 4 wt% of wax or paraffin. The wax or paraffin has a melting point of 40 to 60 DEG C and serves to lower the production temperature of the cement, to melt the cement with chemical resistance, and to provide the effect of not being volatilized and not deteriorating in quality after curing. When the wax or paraffin is added in an amount of less than 3% by weight, the effect of addition is scarcely produced. If the wax or paraffin is added in an amount exceeding 4% by weight, the brittleness of the cement increases,

The styrene thermoplastic elastomer may also be contained in an amount of 1 to 2% by weight. It has a hard segment of polystyrene block in the short term of the sock and a soft segment structure of polybutadiene in the middle. It has a low viscosity when it is dissolved in a mixed solvent and has high elasticity and low temperature durability. The synthetic zeolite powder dispersed in the particulate state exhibits a function of preventing cracking of the waterproof coating film caused by elapsing time and lifting of the waterproof coating caused by lack of low temperature durability during the winter season. The waterproof coating has the advantage of showing additional functions such as soundproofing and sound absorption

And 2.5 to 3.5% by weight of an amine-based curing agent. If the content of the amine-based curing agent is less than 2.5% by weight, the strength and durability may be lowered and the physical properties may be deteriorated. If the content of the amine-based curing agent is more than 3.5% by weight, the viscosity is increased and the workability is deteriorated.

And 1.5 to 3% by weight of an amorphous polyolefin. This amorphous polyolefin (APO) is a strong adhesive material which is obtained by polymerizing olefins such as ethylene and propylene, and lowers the thermal conductivity of cement during the summer season.

Further, it may further contain 0.5 to 0.7% by weight of iron slag. This iron slag is a slag generated when refining steel and scrap iron in an electric furnace to produce steel, preventing plastic deformation of the cement, preventing the port hole on the pavement, and preventing sliding of the road . When the content of the iron slag is less than 0.5% by weight, the effect thereof is not high. When the content of the iron slag is more than 0.7% by weight, the increase in the effect is insignificant.

Based on such a mechanism, the composition of the present invention was prepared as shown in Table 2, and the present invention was confirmed by comparing the performance with that of conventional concrete. The fast curing cement used was Ssangyong cement super fast cement. Cement was also used as Ssangyong cement product. Pozzolan was a Japanese volcanic acid and had a specific gravity of 0.5 g / cm ³ and a specific surface area of 1,500,000 cm ² / g. SSC of Korea I company was used as self-repairing material and INT-AC100 of domestic I company was used as anti-rust agent.

Kinds Fast speed
cement usually
cement Pozzolan Self-repairing material Anti-rust agent sand Pebble water system Example 1 0 14.3 0.4 0.5 0.2 36.3 40.0 6.7 100.0 Example 2 14.3 0 0.4 0.5 0.2 36.3 40.0 6.7 100.0 Comparative Example 1 0 14.3 0 0 0 36.3 40.0 9.4 100.0 Comparative Example 2 14.3 0 0 0 0 36.3 40.0 9.4 100

As can be seen in Table 3, in the case of the example, it was confirmed by photograph that the generated crack was sealed after 28 days, but in the case of the comparative example, the crack progressed more greatly. In addition, the occurrence of rust due to salt spray was measured as 97% and 99% in the case of the examples, and 55% and 48% in the case of the comparative examples, respectively. In the case of water uptake, Examples 1 and 2 showed 0.1 and 0.2 water permeabilities, whereas Comparative Examples were measured at 4.8 and 10.6, respectively. In the case of the water permeability, the water permeability was measured as 1.1 and 2.1 in the Examples and 56.2 and 66.7 g in the Examples The present invention was evaluated to be excellent in waterproof effect by capillary filling. In addition, the compressive strength was also measured to be 331 MPa and 361 MPa in Examples and 312 and 298 MPa in Comparative Examples, respectively, and it was proved that durability can be further improved by using the present invention.

Claims (3)

12 to 20% by weight of cement;
0.1 to 0.5% by weight of an amine-based rust inhibitor;
0.2 to 1.5% by weight of natural pozzolan having a specific surface area of 2,000 to 150,000 cm ² / g;
28.25 to 34.84% by weight of sand;
30 to 40% by weight of aggregate;
0.5-2% by weight of a self-repairing material comprising calcium sulfoaluminate;
4.5 to 11.25 wt% water;
3 to 4% by weight of wax or paraffin;
1 to 2% by weight of a styrene thermoplastic elastomer;
2.5 to 3.5% by weight of an amine-based curing agent,
1.5 to 3% by weight of an amorphous polyolefin; And
0.5 to 0.7 wt% of iron slag;
Wherein the amine-based rust inhibitor and the pozzolanic reaction material are water-soluble.
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