KR102620465B1 - Eco-friendly concrete composition - Google Patents

Abstract

The present invention relates to an eco-friendly concrete composition to which nanomaterials such as calcium carbonate or silicon dioxide are added to maintain rigidity and durability suitable for road paving, etc.

Description

Eco-friendly concrete composition {Eco-friendly concrete composition}

The present invention relates to a concrete composition that is environmentally friendly and can enhance strength and rigidity by replacing at least part of existing concrete materials with slag aggregate, electric furnace oxidation slag, and ferronickel slag.

In the past, various researches are being actively conducted to promote eco-friendliness by replacing existing concrete materials with by-products from various industries.

In general, when producing eco-friendly concrete, Portland cement is usually mixed with fly ash and blast furnace slag fine powder as admixtures. The use of these mixed materials is very advantageous from the perspective of environmental protection by reducing the absolute amount of cement used in concrete production, reducing carbon dioxide emissions generated during cement production, and using industrial by-products as materials.

Typically, such eco-friendly concrete is a three-component concrete that mixes type 1 cement with fly ash and blast furnace slag fine powder, which are industrial by-products, in an appropriate ratio. This three-component concrete is not only environmentally friendly, but also suppresses the heat of hydration and the rate of hydration heat generation. , it also had the effect of improving seawater resistance. (Refer to Korean Patent Publication Nos. 10-1985750, 10-2031784, and 10-2136100)

However, such eco-friendly concrete has the problem of not being able to guarantee sufficient rigidity or durability in an environment where strong loads are repeatedly applied and exposed to a large amount of moisture for a long time, such as in rainy weather, like the concrete used in conventional road paving.

Therefore, in the past, in order to use eco-friendly concrete for road paving, etc., separate materials had to be added to enhance waterproofing, durability, and rigidity. However, if these materials are not industrial by-products but industrial chemical products that must be produced separately, a large amount of carbon dioxide and pollutants are produced during the production of these chemical products.

In addition, if these industrial chemical products are toxic, there is a risk that exposing them to the road environment may cause safety problems.

As a result, there was a fundamental contradiction in that in the process of changing the properties of eco-friendly concrete according to its intended use, separate industrial chemical products had to be produced and mixed to use them.

The present invention aims to solve the problem of providing a concrete composition that can maintain eco-friendly characteristics by using industrial by-products as additives added to eco-friendly concrete.

The present invention aims to solve the problem of providing a concrete composition that can guarantee rigidity or waterproofing like the concrete used in existing road pavements even when industrial by-products are added to eco-friendly concrete.

The present invention aims to solve the problem of providing a concrete composition that can strengthen rigidity through physical action rather than chemical reaction by manufacturing industrial by-products in nanoscale and increasing the surface area of the by-products.

In order to solve the above-described problems, the present invention provides a concrete composition containing a three-component cement containing cement, blast furnace slag, and fly ash.

The concrete composition may further include at least one of slag aggregate, electric furnace oxidation slag, and ferronickel slag, and a reinforcing material that enhances the rigidity of the concrete composition.

The slag aggregate, the electric furnace oxidation slag, and the ferronickel slag are provided to replace at least a portion of sand, and the reinforcing material may be a nanomaterial with a nanometer (nm) size.

The nanomaterial may include at least one of nanometer (nm)-sized calcium carbonate (CaCO3) and nanometer (nm)-sized silicon dioxide (SiO2).

The nanomaterial may be provided in a weight range of 0.5% to 2% of the total weight.

The reinforcing material further includes an additional material added in addition to the nanomaterial, and if the nanomaterial includes the calcium carbonate, the additional material may be an ion-binding material.

The additional material may include at least one of magnesium oxide (MgO), silicon dioxide (SiO2), aluminum oxide (Al2O3), and iron oxide (FeO3).

The reinforcing material further includes an additional material added in addition to the nanomaterial, and if the nanomaterial includes the silicon dioxide, the additional material may be a single element material.

The additional material may include one or more of titanium (Ti), calcium (Ca), sodium (Na), and iron (Fe).

The present invention has the effect of maintaining eco-friendly characteristics by using industrial by-products as additives added to eco-friendly concrete.

The present invention has the effect of ensuring rigidity or waterproofing like concrete used in existing road pavements even if industrial by-products are added to eco-friendly concrete.

The present invention has the effect of enhancing rigidity through physical action rather than chemical reaction by manufacturing industrial by-products in nanoscale and increasing the surface area of the by-products.

Figure 1 shows the characteristics of cement.
Figure 2 shows a case where cement is damaged.
Figure 3 shows the effect of adding nanoparticles to the concrete composition of the first embodiment of the present invention.
Figure 4 shows the effect of adding nanoparticles to the concrete composition of the second embodiment of the present invention.

Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. In this specification, the same or similar reference numbers are assigned to the same or similar components even in different embodiments, and the description is replaced with the first description. As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. Additionally, in describing the embodiments disclosed in this specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed descriptions will be omitted. In addition, it should be noted that the attached drawings are only for easy understanding of the embodiments disclosed in this specification, and should not be construed as limiting the technical idea disclosed in this specification by the attached drawings.

Cement is manufactured by appropriately mixing main raw materials such as limestone, quartzite, clay, iron ore, and gypsum, melting them at a high temperature of about 1450 degrees Celsius, then firing them, adding about 3% of gypsum to the obtained clinker, and then finely pulverizing it.

When this cement reacts with water, a chemical reaction occurs and new hydrates are created, causing the concrete to go through a setting and hardening process. This chemical reaction process is called hydration reaction or hydration.

Figure 1 shows the hydration stage of cement.

Referring to Figure 1, when the hydration heat of ordinary Portland cement is measured using a microhydraulic calorimeter, it can be divided into each stage. The first stage occurs within a few minutes when cement comes in contact with water, and as cement minerals dissolve in water, C ₃ A, which has high dissolution heat and activity, reacts with gypsum to produce ettringite, resulting in the first exothermic peak (point A). appear. The second stage is a stage in which the hydration reaction briefly stagnates within 3 hours after it starts and is called the induction stage. The third stage is called the accelerator, where the reaction progresses at an accelerated rate, and calcium silicate hydrate (CSH) and calcium hydroxide (CH) are produced through the hydration reaction of C ₃ S. At this time, a second exothermic peak (point B) appears due to the heat of formation. The fourth stage is a stage in which the reaction slowly slows down and is called the reducer. In some cements, an additional exothermic peak (point C) may appear due to the heat generated when new ettringite is converted to monosulfoaluminate. The fifth stage is the final stage of hydration and is called the diffusion stage. 20 to 30 hours after hydration, the hydration layer thickens, permeability decreases, and reactivity appears very slowly.

Figure 2 shows the mechanism of alkali silica reaction.

When cement hydrates, alkali-silica reaction (ASR: Alkali Silica Reactivity) may occur.

Alkali-silica reaction is a phenomenon in which alkali hydroxide reacts with the silica component of aggregate to produce an expandable gel. When ASR occurs, cracks occur due to internal expansion, causing serious damage to concrete structures. wake up The chemical reaction between alkali hydroxide and reactive silica is a decomposition reaction in which reactive silica is dissolved in a strong alkaline (high pH) solution. Hydroxyl ions (OH ^- ) attack the siloxane bridge (Si-O-Si) near the surface of reactive silica, decomposing this structure.

At this time, the negatively charged component combines with positively charged alkali ions such as Na ⁺ and K ⁺ to balance it. This is called a gel. As this reaction progresses, the gel exhibits a loose lattice structure. Afterwards, expansion occurs when moisture is supplied from the inside or outside, and when this expansion pressure exceeds the tensile stress of the concrete, cracks occur along the area where the gel was created.

A representative method for suppressing ASR is the emergence of three-component concrete, which replaces admixtures (fly ash and blast furnace slag fine powder) with concrete.

Three-component concrete is a mixed cement and concrete that suppresses the heat of hydration and the rate of hydration heat generation and improves seawater resistance by mixing one type of ordinary Portland cement with fly ash and blast furnace slag fine powder, which are industrial by-products, in an appropriate ratio.

The fly ash is an admixture with the best ASR resistance. The fly ash has the effect of reducing ASR by reacting with hydroxide incidentally generated through the hydration reaction of cement.

The table below shows how fly ash components affect ASR expansion. Because of this effect, the substitution rate or the amount of CaO can be generally adjusted depending on the amount of SiO ₂ +Al ₂ O ₃ +Fe ₂ O ₃ .

Deleterious Constituents
(promote expansion) Beneficial Constituents
(reduce expansion) CaO (calcium oxide) Na ₂ Oand K ₂ O (alkalis) MgO (magnesium oxide)
SO ₃ (sulfur trioxide) SiO ₂ (silicon dioxide) Al ₂ O ₃ (aluminum troxide) Fe ₂ O ₃ (iron oxide)

On the other hand, concrete with the addition of blast furnace slag powder or fly ash reduces calcium hydroxide in concrete through a pozzolanic reaction, thereby reducing hydroxide ions (ions related to alkaline aggregate reaction) in the pore solution and forming low-calcium silicate calcium silicate with a large specific surface area. The formation of hydrates (CSH) and the adsorption of alkaline ions by them, and the densification of the hardened cement paste structure, reduce the speed of water movement and diffusion of Na ⁺ or K ⁺ , greatly reducing the expandability.

In three-component concrete, most of the admixtures are industrial by-product wastes, and they play a big role in the efficient use of resources. During the cement firing process, the decarbonation of limestone is reduced by the amount of admixture used, so the generation of carbon dioxide gas is reduced by the amount of admixture used. It also has excellent social and environmental characteristics, such as preventing global warming.

Currently, in Korea, mixed cements standardized in KS include fly ash cement, slag cement, and Portland pozzolan cement. Although not standardized in KS, three-component cement or four-component cement are widely used in mass concrete and marine concrete structures. There is.

In particular, in the case of three-component cement, various types of mix designs are possible to suit the purpose of construction by combining one type of ordinary Portland cement and the type and amount of admixtures used, and it has superior hydration heat reduction effect and strength development characteristics compared to ordinary concrete. .

The mixed cement mix of three-component concrete generally consists of 30 to 50% of one type of ordinary Portland cement, 10 to 30% of fly ash, and 20 to 60% of fine blast furnace slag powder, and has a specific use purpose. In terms of mechanical and durability characteristics, compared to general portland cement concrete, three-component cement concrete has improved durability and reduced heat of hydration. It densifies and chemically stabilizes the structure of the hardened material through a unique pozzolanic reaction and latent hydraulic reaction, thereby protecting against water and salts. , it can suppress the penetration of sulfate and seawater, and pozzolanic and latent hydraulic materials such as blast furnace slag powder and fly ash have a lower hydration calorific value than general cement, so they can reduce deterioration due to temperature cracking due to heat of hydration.

In other words, it is used for the purpose of low calorific value to prevent temperature rise in mass concrete structures, or to optimize the fineness and mixing ratio of the used admixture and to demonstrate optimal fluidity considering compatibility with the admixture. It can also be used to ensure high performance of concrete, such as high-flow concrete and seawater resistance and chemical resistance. In Europe, the use of various admixtures is actively encouraged, and concrete is used by mixing various admixtures with ordinary cement. In Japan, mixed cement is used for about 20% of all cement. In this way, the use of mixed cement is recommended considering environmental aspects in addition to its excellent physical performance.

The main chemical composition (mixed cement) determined due to the manufacturing characteristics of three-component cement and concrete has a high content of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ), a relatively low amount of lime (CaO), and is similar to that of other cements. Compared to other materials, it has a relatively small density and high powder fineness. In addition, since it is manufactured by mixing fly ash and blast furnace slag fine powder with one type of ordinary Portland cement, the content of aluminate phase (C ₃ A, C ₄ AF) in the cement compound is relatively low, which reduces adsorption of admixtures, increases fluidity, and improves the effect of fine powder. Viscosity increases due to Therefore, it can secure high fluidity and material separation resistance at a low water-binder ratio, so it is applied not only to mass concrete but also to the production of high-performance concrete.

In addition, since the content of the aluminate phase, which generates a lot of initial hydration heat, is low, the hydration heat generation is very small, which can reduce the occurrence of cracks due to hydration heat during large-scale mass concrete construction. Three-component concrete is good because bleeding occurs little by little over a long period of time. Not only can it ensure constructability, but it can also prevent deterioration in the quality of concrete after hardening. The setting of concrete is delayed compared to concrete using type 1 ordinary Portland cement, and as the amount of admixtures such as fluidizers increases, the tendency for setting delay increases.

Three-component concrete forms a dense microstructure through the pozzolanic reaction of calcium silicate hydrate (C-S-H), a hydration product, and admixtures, so it not only suppresses erosion by chemical solutions such as sulfur dioxide and chloride, but also maintains strength even under chemical attack conditions. Shows improvement. In particular, when immersed in seawater, there is almost no decrease in strength compared to other cements because the fine structure of the hydrate generated by the pozzolanic reaction and the ion adsorption of the hydrate suppress the penetration of ions.

In addition, three-component concrete has the effect of suppressing the alkaline aggregate reaction because the pozzolanic reaction of the admixture consumes the calcium hydroxide generated during the cement hydration reaction, lowering the pH in the concrete.

The problem with using three-component concrete is that less calcium hydroxide (Ca(OH) ₂ ) is produced than regular cement due to the nature of the material composition, so calcium hydroxide (Ca(OH) 2 ), which can fix carbon dioxide into calcium carbonate (CaCO ₃ ), is used. ) Due to the insufficient amount of ₂ ), there is a possibility that neutralization may be promoted compared to general cement concrete. However, there is also an aspect that the structure of the hardened body becomes more dense due to the pozzolanic reaction that actually consumes calcium hydroxide, making it difficult for carbon dioxide to flow in from the outside.

Fly ash, a representative admixture widely used when mixing concrete, is mainly used to improve the properties of concrete, such as heat of hydration, improved workability, and improved flame resistance, and has a cost-saving effect, making it a material with a fairly high usage rate.

Domestic coal-fired power plants include those that use domestic anthracite with an ash content of about 45% and those that use imported bituminous coal with an ash content of about 10 to 15%. Because fly ash generated from anthracite-fired power plants has a high unburned carbon content, only fly ash generated from bituminous coal-fired power plants serves as an admixture used when mixing concrete.

When pulverized coal is burned in a boiler combustion chamber in a coal-fired power plant, among the remaining coal ash, fly ash is collected in the hopper under the economizer or air preheater, and is collected by the electrostatic precipitator and visible in the dust collector hopper. The clinker ash recovered from the bottom of the boiler, the cinder ash recovered from the coal economizer and air preheater, and the fly ash collected from the dust collector are all called coal ash, of which fly ash accounts for approximately 80%. .

The quality characteristics of fly ash generated by changes in the type of bituminous coal in thermal power plants, changes in combustion chamber operation conditions, and changes in pulverized coal change in quality characteristics such as unburned carbon content, vitrification rate, pozzolanic reactivity of the glass portion, and particle size distribution.

As combustion temperatures are being managed downward due to the recent strengthening of nitroxide emission standards, the unburned carbon content tends to increase in particular. In most cases in Korea, fly ash is purified using the air classification method.

There are two regulations for fly ash for concrete: KS L 5405 (fly ash) when used as an admixture and KS K 5211 (fly ash cement) when used as a cement when mixed, but as a mixed cement (Type A: 5~10%, B Species: 10 to 20%, C species: 20 to 30%) are rare and only mixed materials are used. The density of fly ash tends to be high when there is a lot of iron in the chemical components, and tends to be low when the carbon content is high.

The strength of concrete in which fly ash is replaced by cement by weight decreases slightly at an early age compared to concrete without fly ash, but the long-term strength increases significantly.

This is because, in the pozzolanic reaction in which calcium hydroxide, a hydration product of cement, and soluble silica and alumina of fly ash combine, the pozzolanic product does not significantly contribute to the development of strength until it is filled around the fly ash particles, but in the later age, the soluble silica and alumina of fly ash combine. This is because the ment-paste is firmly bonded to the pozzolanic product, improving strength, watertightness, and durability. In general, the strength improvement of concrete using fly ash becomes noticeable after 36 months.

Silica fume is mixed to improve the initial strength of concrete using fly ash. This is because calcium hydroxide is sufficiently supplied for continuous pozzolanic reaction in the early and long-term stages. Another method is to increase the initial strength by using a high-performance water agent instead of reducing the water-binder ratio. The strength development secured by the hydration reaction of Portland cement continues to increase even at later ages due to the pozzolanic reaction of fly ash if moisture is maintained in the concrete. Therefore, the long-term strength of concrete using fly ash is improved compared to the initial stage. This result is because the interface between the fly ash and the cement hardening body is filled with pozzolanic reaction products, and the bonding strength between them increases with age.

The longer the age, the higher the strength development ratio, so it is effective when mixed into cement. As a result of a long-term study, fly ash concrete had a 50% strength increase after one year, while concrete without fly ash had only a 30% strength increase. The performance of fly ash concrete was found to be excellent even at an age of more than 10 years. Therefore, fly ash can be used as an important material to produce high-strength concrete.

Like the compressive strength, the elastic modulus of concrete using fly ash was slightly lower at early ages and slightly higher at later ages compared to concrete without fly ash. The effect of fly ash on elastic modulus is not as significant as on compressive strength. It can be seen that the effect on the elastic modulus is more significant depending on the characteristics of cement or aggregate than fly ash.

At most strength levels, the elastic modulus of concrete using fly ash shows a similar trend to that of general concrete without fly ash. Even in the case of concrete using fly ash, it is desirable to evaluate the elastic modulus based on strength.

The amount and rate of creep deformation of concrete depend on ambient temperature, humidity, concrete strength, elastic modulus, corrugation, concrete age and strength at loading, and sustained creep stress ratio. The effect of fly ash on the creep of concrete is very limited, as is the effect of fly ash on strength development. Fly ash concrete with an age of 28 days shows a higher creep deformation compared to concrete using only cement of the same volume, because the strength of fly ash concrete when loaded is relatively low. However, if the concrete strength at the beginning of loading for creep measurement is the same, the creep deformation of concrete using fly ash decreases at all ages.

The drying shrinkage of concrete varies depending on the volume of cement-paste, unit quantity, type and amount of cement used, and type of aggregate. When the unit quantity is constant, concrete using fly ash tends to slightly increase drying shrinkage because the volume of the binder-paste increases.

However, because the unit quantity can be reduced by using fly ash, the drying shrinkage of fly ash concrete is the same or reduced than that of concrete without fly ash, and it also has a crack prevention effect.

The drying shrinkage of concrete mixed with 20% fly ash is almost the same as that of concrete without fly ash.

There are also results showing that drying shrinkage slightly decreases when the amount of fly ash mixed is increased. These results are due to the decrease in unit quantity and the action of gypsum contained in fly ash.

Meanwhile, factors that affect the watertightness of concrete include binder, unit quantity, aggregate particle size, density, and curing method. In general, Ca(OH) ₂ precipitated by cement hydration is water-soluble, so it is easily dissolved when water penetrates.

However, when fly ash with pozzolanic properties is used, the possibility of Ca(OH) ₂ dissolving is reduced because it reacts with calcium, potassium, and sodium when producing CSH.

At the initial age, the water tightness of concrete using fly ash is lower or similar to that of concrete without fly ash, but in the long term, it increases significantly due to the pozzolanic reaction of fly ash.

In addition, by suppressing water infiltration, the resistance to physical and chemical erosion of concrete structures is increased and durability is also improved.

In addition, water tightness increases as the fineness of fly ash increases. This is because fine particles fill the large pores of cement paste and reinforce the pores. It is known that the improvement in water tightness of concrete using fly ash is greater than the improvement in strength.

Meanwhile, the freeze-thaw resistance of concrete depends on air entrainment, stability of aggregate, age, degree of hydration, cement paste strength, and humidity conditions of concrete rather than fly ash mixing. Because concrete using fly ash has a slow initial strength development, the amount of binder must be increased to develop a degree of hydration suitable for 28 days, and the amount of air entraining agent added per unit volume of concrete must also be increased.

Since the particle size distribution of air entrained in concrete using fly ash shows little change compared to that without fly ash, the freeze-thaw resistance is known to be similar when strength and air volume are simultaneously compared.

In general, alkaline aggregate reaction refers to a reaction in which the alkaline component contained in materials such as cement and the silica component contained in the aggregate gradually create a new substance over a long period of time in the presence of moisture. The product of this reaction absorbs moisture and has an expansion effect. This causes cracks and peeling of concrete, and in severe cases, collapse.

When fly ash is used in concrete, the silica-based glass of the fly ash reacts with the alkali hydroxide of the cement paste, consuming the amount of alkali in the concrete that causes expansion when it reacts with the silica of the aggregate. Therefore, using an appropriate amount of fly ash can reduce the reaction of aggregate and prevent harmful expansion of concrete.

Fly ash as well as blast furnace slag are potential hydraulic materials that only absorb some moisture when they come into contact with water and do not exhibit any hardening properties through chemical reactions. However, if the overall alkalinity in the concrete increases due to the cement hydration reaction and stimulates the particle surface of the admixture, the chemical components of these particles may elute and react with surrounding components to exhibit hardening characteristics. The admixture itself does not have hydraulic properties, but the soluble components contained in it, such as SiO ₂ and Al ₂ O ₃ , slowly react with Ca(OH) ₂ generated when the cement constituent compounds C ₃ S and C ₂ S hydrate at room temperature, making them insoluble. This produces stable calcium silicate hydrate (CSH) or calcium aluminate hydrate (CAH), which is called a pozzolanic reaction.

Fly ash and blast furnace slag fine powder are binders that undergo a pozzolanic reaction. Calcium hydroxide produced as a result of a hydration reaction upon contact with water, such as cement constituent compounds C ₃ S and C ₂ S, and soluble components such as silica and alumina of fly ash. The reaction produces calcium silicate or calcium aluminate hydrate as a secondary product. Cement paste that has undergone a hydration reaction contains approximately 70% calcium silicate and 20% calcium hydroxide. It contains calcium hydroxide generated as a result of a hydration reaction. Calcium hydroxide generated as a result of the hydration reaction creates voids inside the hardened body and acts as a factor in reducing performance. When using fly ash and blast furnace slag fine powder, it can contribute to improving the performance of concrete by binding calcium hydroxide.

CH + S + H C-S-H; CH+A+H C-A-H

In addition to the pozzolanic reaction, blast furnace slag fine powder forms the main hydrate produced during the cement hydration reaction due to a latent hydraulic reaction caused by alkaline components including calcium hydroxide when mixed with cement and hydrated with water. Although the hydration reaction rate is slower than that of ordinary Portland cement, alkali and ordinary Portland cement increase the hydration reaction rate, and in the mixed acid hydration reaction of blast furnace slag fine powder and ordinary Portland cement, the blast furnace slag fine powder contains potassium, sodium, alkali, and CH. It reacts with to form calcium silicate hydrate.

The blast furnace slag may be generated in the following process. When reducing and refining metal oxides in ore, the low melting point material to which limestone is added is called slag, which is separated from the metal and remains when removed. It is separated into steel slag and non-ferrous slag. Non-ferrous slag is divided into copper, nickel, and silver slag depending on the non-ferrous metal being reduced. Steel slag is blast furnace slag produced during pig iron production and converter slag produced in the converter of the pig iron refining process. It is classified as Such slag has potential hydraulic properties and can be used for various purposes.

quality 1 type 2 types 3 types Density (g/cm ³ ) 2.80 or higher 2.80 or higher 2.80 or higher Specific surface area (cm ² /g) 8,000~10,000 6,000~8,000 4,000~6,000
Activity index (%) Age 7 days 95 and above 75 and above over 55 Age 28 105 or higher 95 and above 75 and above Age 91 days 105 or higher 105 or higher 95 and above Flow value ratio (%) 95 and above 95 and above 95 and above Magnesium Oxide (MgO) (%) below 10 below 10 below 10 Sulfur trioxide (SO ₃ ) (%) 4 or less 4 or less 4 or less Ignition loss (%) 3 or less 3 or less 3 or less Chloride ion (%) 0.02 or less 0.02 or less 0.02 or less

Quality regulations for blast furnace slag fine powder (KS F 2563)

type Blast furnace slag content (%) 1 type More than 5 but less than 30 2 types Above 30 but below 60 3 types Above 60 but below 70

Types of blast furnace slag cement (KS L 5210)

Blast furnace slag is created when added limestone reacts with the veins of iron ore, combustion ash of coke, and various oxidizing substances, and is separated and discharged by the difference in specific gravity from pig iron in a high-temperature molten state. Blast furnace slag can be classified according to the cooling method: quick-cooled slag, semi-quick-cooled slag, and slow-cooled slag. Among these, slowly cooled slag is naturally cooled and mostly crystallizes, so it has low potential hydraulic properties and is therefore unsuitable as a cement mixture. Quickly cooled slag is highly reactive because high temperature slag is rapidly cooled by water, air, etc., so it is used as blast furnace cement slag or cement. It is used as a mixing material.

The KS standard for blast furnace slag fine powder used in domestic concrete is KS F 2563 [Blast furnace slag fine powder for concrete]. The quality regulations for blast furnace slag fine powder for concrete specified in KS F 2563 are as shown in the table below. The main quality standards are classified into 1 to 3 types of blast furnace slag fine powder depending on the fineness, the density is specified as 2.80g/cm ³ or more, and the basicity of crushed blast furnace slag is specified as 1.60 or more.

Concrete using the fine powder of the blast furnace slag as an admixture shows different compressive strength depending on the name of the fine powder of the blast furnace slag, the powder degree and substitution rate, and the difference in age. The compressive strength of concrete mixed with blast furnace slag fine powder with a fineness of about 5,000 cm ² /g or less decreases at the beginning of aging compared to that without mixing, but the decrease in strength improves with aging, and at long-term aging, it is as good as that without mixing. It surpasses that of

In addition, when the chemical composition or glass mass of the slag is the same, the greater the fineness of the slag, the greater the surface area, and thus the greater the reactivity. The initial strength decreases compared to Portland cement concrete as the mixing ratio increases, and this tendency becomes more noticeable as the substitution ratio increases and the water-cement ratio decreases. However, as the fineness of slag increases, the difference in initial strength decreases, and when the fineness exceeds a certain level and an appropriate amount of gypsum is added, the initial strength becomes superior to that of Portland cement concrete. The ratio of compressive strength increases with age, and even when a large amount of slag is mixed at 70%, the compressive strength of concrete that has been cured in water at 20 degrees Celsius for 3 to 6 months is at least the same as that without slag. It gets big enough.

In addition, even when slag with a small fineness is mixed, the development of strength is large when aged for a long period of time, and when the aged is about 91 days, the effect of fineness on the compressive strength is not so significant. In long-term aging, the strength recovery of concrete replaced with slag depends on the latent water hardening of the slag. Therefore, as the fineness of the slag increases, the hydration reaction becomes more active, the development of latent hydraulic properties is further promoted, and the initial strength is improved.

Cracks in concrete have a significant impact on the structural strength and durability of a structure. In general, the hydration reaction of concrete using fine blast furnace slag powder is slightly slow, and the moisture dissipation from the surface is initially greater than that of ordinary concrete, so the test method specified in JIS A 1129 (Length change test method for mortar and concrete) is used. In the case of testing according to , the curing shrinkage rate is added to the drying shrinkage rate, and the initial shrinkage rate shows a large value compared to unmixed concrete.

However, caution is required as this occurs when wet curing is insufficient. Using 4,000cm ² /g, 6,000cm ² /g and 8,000cm ² /g of blast furnace slag fine powder, the drying shrinkage rate at 1 year of concrete age with a substitution rate of 30 to 70% and a water-binder ratio of 25 to 55% is 70x10 ^- Before and after ⁴ , it is almost the same as unmixed concrete.

Meanwhile, the drying shrinkage strain rate of concrete mixed with blast furnace slag fine powder is shown. There is no significant difference in the drying shrinkage strain rate between concrete mixed with blast furnace slag fine powder and concrete without mixed blast furnace slag powder.

The higher the fineness of the blast furnace slag fine powder, the smaller the self-contraction strain rate appears. It can be seen that it is effective to increase the fineness of the blast furnace slag fine powder to suppress cracking of high-strength concrete due to self-contraction deformation.

On the other hand, there is very little data on the creep of concrete mixed with blast furnace slag fine powder, but creep is observed in the air environment when loaded immediately after standard curing at 20 degrees Celsius for 7 or 28 days or when loaded after curing for a certain period of time. is slightly smaller than regular concrete without slag. Additionally, the basic creep in aquatic environments is greatly reduced by the use of slag. And the creep coefficient decreases as the substitution ratio of slag increases and the fineness increases.

Concrete using fine blast furnace slag powder improves the chemical resistance of Portland cement concrete. Portland cement contains minerals (C ₃ S, C ₂ S) that release large amounts of calcium hydroxide when hydrated or minerals (C ₃ A) that produce double salts in the presence of sulfate or chloride. When fine blast furnace slag powder is used, calcium hydroxide, which is diluted and released at the same time according to the substitution ratio, causes a pozzolanic reaction with silicate or aluminate eluted from the slag in the capillary pores, and some of it is consumed to form a dense tissue structure and permeate. It reduces the water content and thus inhibits the penetration of salts.

Meanwhile, three-component concrete is a concept that includes not only the combination of blast furnace slag and fly ash cement, but also coarse aggregate, fine aggregate, and other additives.

Even if at least one of the blast furnace slag and fly ash can replace cement, the coarse aggregate and fine aggregate themselves cannot be completely replaced.

When concrete is made with three-component cement, moisture is contained deep inside the concrete, which not only takes a long time to cure and harden, but also requires too much cement to form a specific volume of concrete, which is not economically superior. Therefore, the unit quantity and unit cement quantity can be reduced through coarse aggregate such as gravel, and the strength of the aggregate itself is high, so the strength of the entire concrete can be reinforced due to the strength of the aggregate itself.

The blast furnace slag can replace at least part of the coarse aggregate with gravel, thereby saving natural resources input into the concrete itself, thereby further improving eco-friendliness.

However, when only coarse aggregate is used, voids or empty spaces occur between the coarse aggregates, which does not guarantee the durability of the concrete itself. Therefore, there is a need for a fine aggregate that can improve the bonding strength between the cement and the entire aggregate by filling the voids with fine aggregate that has a smaller particle size than the coarse aggregate such as gravel.

The fine aggregate may generally be sand such as silicon-based sand.

Meanwhile, the sand is also a natural material, and in order to use it for concrete production, environmental destruction due to mining and transportation of sand may be a problem. Therefore, in order to produce eco-friendly concrete, sand can be replaced with the slag aggregate, electric furnace oxidation slag, and ferronickel slag.

For example, it is made of one or more selected from the group consisting of ferronickel slag and blast furnace slag or granulated blast furnace slag, electric furnace oxidation slag, and slag aggregate, and the strength, flexural strength, adhesion strength, abrasion resistance, freezing resistance, and melting resistance of the concrete , plays a role in improving physical properties such as chlorine ion penetration resistance.

The ferronickel slag is produced in more than 150,000 tons annually at domestic ferronickel smelters, and an alloy made with a composition ratio of 80% iron and 20% nickel is called ferro-nickel, and nickel ore is used to produce ferronickel. During smelting, the by-product generated while passing through production lines such as raw materials, iron making, and steelmaking is called ferro-nickel slag.

The raw material for ferronickel is nickel oxide ore, and the nickel grade is 2 to 25% by weight.

It is very low, and most of the other contents, such as SiO2, MgO, FeO, and CaO, are generated as slag, generating about 1 million tons of ferronickel slag.

The main components of ferronickel slag are 40 to 50% by weight of CaO and 30 to 40% by weight of MgO, and are in the form of spherical sand with a particle size of less than 10 mm.

In addition, blast furnace slag, slag aggregate, and electric furnace oxidation slag are obtained by rapidly cooling molten blast furnace slag, which is produced simultaneously with pig iron in a blast furnace, with high-pressure water or air. In particular, as slag is discharged from the blast furnace, high-pressure water is sprayed, so it has a crystalline phase. It is produced as amorphous sand-like particles.

Above, the ferronickel slag has a low water absorption rate and a spherical particle shape, making concrete

When used as a fine aggregate, it improves fluidity and can produce watertight concrete, thereby improving the strength and durability of concrete.

In addition, the blast furnace slag reduces the risk of material separation due to the high specific gravity of ferronickel slag when mixed with ferronickel slag, and has the effect of increasing bonding strength with cement due to surface hydraulic potential.

In other words, when steel slag mixed with ferronickel slag and blast furnace slag or granulated blast furnace slag is used as a fine aggregate, quality uniformity of concrete can be secured and a concrete composition that improves physical performance and durability is provided.

At this time, the ferronickel slag preferably has a particle size of 15 to 5 millimeters. If the particle size of the ferronickel slag is less than 15 millimeters, it overlaps with the particle size distribution of granulated blast furnace slag and deviates from the standard particle size. Therefore, excessive cement is required during concrete production, which reduces economic efficiency, and the particle size of the ferronickel slag is 5 mm. If it exceeds millimeters, the spherical nature of the particles is lost, resulting in a decrease in fluidity during concrete production.

In addition, the granulated blast furnace slag preferably has a particle size of 008 to 25 millimeters. If the particle size of the granulated blast furnace slag is less than 008 millimeters, the viscosity increases during concrete production, thereby deteriorating the surface finishing work, and the granulated blast furnace slag If the particle size exceeds 25 millimeters, the particle size distribution overlaps with that of ferronickel slag and deviates from the standard particle size distribution. Therefore, excessive cement is required when producing concrete, which reduces economic efficiency.

In addition, it is preferable that the mixing ratio of the ferronickel slag and granulated blast furnace slag is 1:04 to 1, wherein the granulated blast furnace slag serves to lower the high specific gravity of ferronickel slag and has a small size of 25 mm or less. It has the effect of filling the particle size to achieve a standard particle size distribution, and the bonding strength with cement is increased due to the latent hydraulic properties of the surface, thereby improving bending strength, adhesion strength, and waterproofing performance.

Meanwhile, concrete or three-component concrete can be produced using three-component cement and coarse aggregate and fine aggregate used as eco-friendly materials.

However, when the concrete is used as a paving material for roads on which vehicles travel, excessive loads are applied repeatedly, intensively, and continuously. Therefore, even if concrete is manufactured in an eco-friendly manner, it may lack durability or rigidity to withstand adverse conditions such as roads.

Accordingly, by adding a large amount of chemical additives or adjuncts such as latex to the three-component concrete, durability and strength can be strengthened and temperature deformation and self-contraction deformation of concrete can be suppressed.

However, there is a problem in that additives such as latex cannot achieve the rigidity or durability of concrete that is optimally suited to road conditions.

Moreover, adding a large amount of chemical additives such as latex can cause problems in the environment due to the toxicity of the latex itself, and when manufacturing the latex, a number of contaminants are generated, which does not meet the purpose of producing eco-friendly concrete. It may not be possible.

Therefore, the concrete composition or three-component concrete composition of the present invention can further improve strength and durability by adding nanometer-sized additives compared to common additives such as latex.

Of course, additional costs are incurred to manufacture the nanometer-sized additives (hereinafter referred to as nanomaterials), and in situations where concrete is needed, such as a general construction site, there is no room for use due to the problem of excessive cost.

In particular, the use of expensive nanomaterials in the process of using industrial by-products in the process of saving concrete costs is inconsistent with the purpose of producing eco-friendly concrete, so concrete containing nano-sized additives cannot be used throughout the industry. There wasn't.

However, in harsh environments such as roads where there is long-term traffic and exposure to large amounts of water during rainy weather, problems with concrete damage were frequent, and road maintenance processes occurred repeatedly.

Maintenance work on these roads incurs material costs, labor costs, equipment operation costs, etc., and traffic must be controlled for a certain period of time, resulting in very large social costs. Therefore, in environments where concrete maintenance occurs frequently, such as roads, etc., even if the nano-sized additive itself is expensive, it may be cheaper overall to use concrete in which durability and rigidity can be secured by adding nanomaterials. .

Therefore, the concrete of the present invention can further improve the durability and rigidity of concrete by adding nanomaterials to concrete, and this can be actively used for paving roads, etc.

Figures 3 and 4 show the effect of increasing the strength of the concrete composition of the present invention to which nanomaterials are added.

Since the nanomaterial is very small in size when added to the concrete composition, it can move without being hindered by the three-component cement, fine aggregate, and coarse aggregate.

Therefore, the nanomaterial can be spread evenly throughout the concrete composition by movement due to osmotic pressure or concentration difference, or can be easily delivered to the fine pores generated inside the concrete composition.

The nanomaterial has a much larger surface area than micro-sized materials or mm-meter-sized materials for the same mass. Due to this expanded surface area, even if the same mass of additives is added, the nanomaterial can generate strong adhesion by contacting the concrete composition.

For example, even if the nanomaterial does not chemically react or combine with the concrete composition, it can generate strong adhesion due to the attractive force generated inherent in the material, such as van der Waals force.

Accordingly, even if the nanomaterial is added in a small amount, the bonding force of the concrete composition can be greatly strengthened or the pores of the concrete composition can be filled in detail.

The nanomaterial may be made of a material such as calcium carbonate or silicon dioxide that does not chemically react with the concrete composition or water. This is because if the nanomaterial reacts chemically with the concrete composition, it cannot spread throughout the concrete composition when added to the concrete composition.

Meanwhile, when the nanomaterial reacts chemically with the concrete composition, reactivity can be further improved because the unit cross-sectional area per particle is very large. Therefore, if the nanomaterial fills voids or causes a pozzolanic reaction even when it is micrometer or millimeter in size, the degree to which it fills the void or causes a pozzolanic reaction will greatly increase if the nanomaterial is provided in nanometer sizes. will be.

Therefore, the impact of the nanomaterial on the concrete composition can be maximized.

Specifically, the nanomaterial may be made of calcium carbonate having a thickness of 50 nm or less.

When the calcium carbonate is added to the concrete, it hardly reacts chemically even though it is composed of nanomaterials. Therefore, when the nanometer-sized calcium carbonate is added to the concrete, it can spread evenly throughout the concrete through osmotic pressure or the like, and can strongly adhere to the concrete composition through van der Waals forces or the like.

In addition, the nanometer-sized calcium carbonate can be delivered to the micropores of the concrete and fill the micropores due to its characteristic of not chemically reacting.

As a result, the nanometer-sized calcium carbonate provided at 50 nm or less can effectively improve the durability and rigidity of the poured concrete.

On the other hand, when the calcium carbonate is provided in an amount of 50 nm or more, the effect of improving the strength or durability of the entire concrete composition may rapidly decrease. This means that if it is provided at 50nm or more, the area per unit particle is not sufficient for the Van Der Waals force to generate sufficient adhesion, or the speed or degree of diffusion within the concrete due to collision with the concrete composition may be insufficient. It can be understood as decreasing.

Meanwhile, the nanomaterial may further include a first additional material in addition to the nanometer-sized calcium carbonate itself. The first additional material may be provided to further amplify the performance of the nanometer-sized calcium carbonate without changing the physical and chemical properties of the nanometer-sized calcium carbonate.

The ratio of these additional materials and the nanometer-sized calcium carbonate may be set not to exceed 2 to 98 in mass ratio. For example, a nanometer-sized amount of calcium carbonate would be 98 and the total mass of the additional material would add up to 2.

Considering the specificity of the reaction with calcium carbonate, the first additional material may be at least one of magnesium oxide (MgO), silicon dioxide (SiO2), aluminum oxide (Al2O3), and iron oxide (FeO3). Of course, the first additional material may also be provided in nanometer size.

The first additional material may not be a single element in common, but may be comprised of ionic bonds such as redox reactions. When the first additional material is added to the concrete together with the nanometer-sized calcium carbonate, it is ionized and may contribute to increasing the propagation power of the nanometer-sized calcium carbonate or to increasing the bonding force between the calcium carbonate and the concrete composition. .

In addition, the additional material must be added in a very small amount to ensure that it does not interfere with the role of the calcium carbonate. Through very precise experiments, it was determined that the magnesium oxide should not be more than 0.35 percent of the total nanomaterial so that the calcium carbonate in the nanoparticles assists and does not hinder the strengthening and strengthening of the concrete composition.

Specifically, when the first additional material includes silicon dioxide, the silicon dioxide should not be more than 0.1 percent of the total nanomaterial so that the calcium carbonate of the nanoparticles can help strengthen the durability and rigidity of concrete. there is.

In addition, when the first additional material includes the iron oxide, the iron oxide should not be more than 0.1 percent of the total nanomaterial so that the calcium carbonate of the nanoparticles can help strengthen the durability and rigidity of the concrete composition.

In addition, when the first additional material includes the iron oxide, the aluminum oxide should not be more than 0.1 percent of the total nanomaterial, so that the calcium carbonate of the nanoparticles can help strengthen the durability and rigidity of the concrete composition. .

The first additional material may be composed of any one of magnesium oxide, silicon dioxide, aluminum oxide, and iron oxide. However, the first additional material may include all of the magnesium oxide, silicon dioxide, aluminum oxide, and iron oxide.

Meanwhile, the nanomaterial may be made of nanometer-sized silicon dioxide.

Even when the nanomaterial is comprised of silicon dioxide, the nanomaterial can greatly improve the strength and durability of the concrete. When the silicon dioxide is added to the concrete composition, unlike calcium carbonate, it causes a pozzolanic reaction with calcium hydroxide and the like.

At this time, when the silicon dioxide is provided as nanometer-sized nanoparticles, the pozzolanic reaction occurs more violently. In other words, the absolute amount of silicon dioxide that reduces hydroxide ions (ions related to alkaline aggregate reaction) increases, so that the ASR reaction of early concrete can be significantly prevented. Furthermore, the generation of low-calcium calcium silicate hydrate (CSH) with a large specific surface area increases the degree or amount of filling the voids inside the concrete, greatly enhancing the durability and rigidity of the overall concrete. Furthermore, the degree to which the adsorption of alkaline ions and the reduction in the speed of water movement and diffusion of Na ⁺ or K ⁺ due to the densification of the hardened cement paste structure is greatly amplified, further reducing the expandability of the concrete itself, thereby increasing the durability of the concrete. It can be further strengthened. The silicon dioxide may also be provided at a thickness of 50 nm or less.

Meanwhile, the nanomaterial may further include a second additional material in addition to nanometer-sized silicon dioxide.

The second additional material may be provided to further amplify the performance of the nanometer-sized silicon dioxide without changing the physical and chemical properties of the nanometer-sized silicon dioxide.

The ratio of this second additional material to the nanometer-sized silicon dioxide may be 2 to 98 or 1 to 99 in mass ratio.

Depending on the specificity of the reaction with silicon dioxide, the second additional material is not magnesium oxide (MgO), silicon dioxide (SiO2), aluminum oxide (Al2O3), or iron oxide (FeO3), but titanium (Ti), calcium (Ca), It may contain single elements such as sodium (Na) and iron (Fe).

When the second additional material includes titanium, the titanium should be added at less than 220 ppm based on the entire concrete composition so that the silicon dioxide of the nanoparticles can help strengthen the durability and rigidity of the concrete composition.

When the second additional material includes the calcium, the calcium should be added at less than 130 ppm based on the entire concrete composition so that the silicon dioxide of the nanoparticles can help strengthen the durability and rigidity of the concrete composition.

When the second additional material includes the calcium, the sodium should be added at less than 80 ppm based on the entire concrete composition to help the silicon dioxide of the nanoparticles strengthen the durability and rigidity of the concrete composition.

When the second additional material includes iron, the iron should be added in an amount of less than 40 ppm based on the entire concrete composition so that the silicon dioxide of the nanoparticles can help strengthen the durability and rigidity of the concrete composition.

The second additional material may include only one of titanium, calcium, sodium, and iron, or may include titanium, calcium, sodium, and iron.

Below, the effects of adding the nanomaterials to concrete made from various concrete compositions are explained in tables and graphs.

As described above, the nanomaterial is provided as nanometer-sized particles and may include at least one of calcium carbonate and silicon dioxide. Additionally, the nanomaterial may further include any one of the first additional material and the second additional material.

When the nanomaterial includes the calcium carbonate, the nanomaterial may further include the first additional material.

When the nanomaterial includes the silicon dioxide, the nanomaterial may further include the second additional material.

Figure 3 shows the effect of adding the nanomaterial to the concrete composition of the first embodiment of the present invention.

The concrete composition of the first embodiment of the present invention may require physical properties as shown in the table above to maintain certain durability and strength even in harsh environments such as roads.

Specifically, in order to satisfy the physical properties required for the concrete composition of the first embodiment, the diameter of the aggregate should not exceed 13 mm, and the rigidity should be maintained at 35 MPa or more. In addition, fluidity must be secured to ensure a slump of 190 mm, and the internal void ratio must be managed within the range of 3 to 6%. The combination ratio of water and binder should be 38%, and the fine aggregate ratio may be 55%.

Formulations that can satisfy these conditions are shown in the table above. In order for the concrete composition road of the first embodiment of the present invention to be paved so as to maintain durability in the environment, 107 kg/m3 of water, 200 kg/m3 of cement, 60 kg/m3 of fly ash, 140 kg/m3 of blast furnace slag, and 908 kg/m3 of sand were used. m3, gravel 752 kg/m3, and latex 85 kg/m3. The strength change over time of the concrete composition of the first embodiment without nanomaterials is as follows.

When nanoparticles are not added to the concrete composition of the first example mixed in this way, the change in strength over a period of time can be measured, and this can be set as a control group against which the effect of nanomaterials can be compared.

The effect of nanomaterials can be confirmed by measuring and comparing the change in strength over a period of time when nanomaterials are added to the concrete composition of the first example based on the control group.

Specifically, the table shows the change in strength over a specific period of time when nanomaterials were not added to three specimens of the concrete composition of the first example.

It can be seen that the average strength of the concrete of the first example is 27.04 MPa on the 7th day, and that the average strength increases as it hardens to 37.43 MPa on the 28th day.

The above table shows the change in strength over a specific period of time when nanomaterials composed of silicon dioxide were added to three specimens of the concrete composition of the first example at a rate of 1% of the total weight.

It can be seen that in the concrete of the first example, when nanomaterials made of silicon dioxide were added, the average strength value was 32.44Mpa on the 7th day, and the average strength value was 45.52Mpa on the 28th day.

In other words, when nanomaterials containing silicon dioxide were added, the strength increased by an average of 19.95% on the 7th day compared to when the nanomaterial was not added, and on the 28th day, the strength increased by an average of 21.62%.

The above table shows the change in strength over a specific period of time when nanomaterials composed of calcium carbonate were added to three specimens of the concrete composition of the first example at a rate of 1% of the total weight.

It can be seen that the concrete of the first example had an average strength of 29.04Mpa on the 7th day and 40.24Mpa on the 28th day when nanomaterials made of calcium carbonate were added.

In other words, when nanomaterials containing calcium carbonate were added, the strength increased by an average of 7.4% on the 7th day compared to when the nanomaterial was not added, and on the 28th day, the strength increased by an average of 7.5%.

However, it can be seen that the rate of increase in strength is lower than when the nanomaterial containing silicon dioxide is added.

The table above shows the change in strength over a specific period when nanomaterials containing both calcium carbonate and silicon dioxide were added to three specimens of the concrete composition of the first example at a rate of 0.5% of the total weight.

In other words, when nanomaterials containing both calcium carbonate and silicon dioxide were added to the concrete of the first example, the average strength value was 29.90Mpa on the 7th day, and the average strength value was 39.35Mpa on the 28th day. .

That is, when nanomaterials containing both calcium carbonate and silicon dioxide were added, the strength increased by 10.56% on average on the 7th day compared to when no nanomaterials were added, and on the 28th day, the strength increased by 5.13% on average. Able to know.

However, it can be seen that the rate of increase in strength is lower than when the nanomaterial containing silicon dioxide is added. Moreover, it can be seen that the trend of further increase in strength compared to when the nanomaterial containing calcium carbonate was added was not confirmed.

Figure 3 is a graph showing the change in intensity continuously measured during a specific period as shown in the table above. Based on the concrete composition of the first embodiment, the x-axis of the graph represents the period, and the y-axis represents the change in rigidity of the concrete composition over time.

Through the graph of FIG. 3, it is possible to see at a glance not only the effect of nanomaterials, but also what nanomaterials are made of that are more effective.

Referring to the graph of FIG. 3, no nanomaterials were added to the concrete composition of the first embodiment mixed at the above specific gravity during a specific period, and 1% of the total specific gravity of nanomaterials was added to the concrete composition of the first embodiment mixed at the above specific gravity. Addition of nano-sized nanomaterials of silicon dioxide, 1% of the total weight of nano-sized calcium carbonate nanomaterials added to the concrete composition of the first example mixed at the above-mentioned specific gravity, and addition of nano-sized calcium carbonate nanomaterials of the first embodiment mixed at the above-mentioned specific gravity. The change in rigidity can be seen when a nanomaterial containing 1% of the total weight of nano-sized calcium carbonate and silicon dioxide was added to the concrete composition of the example.

By analyzing the graph, it can be seen that the strength of the concrete composition of the first example without adding nanomaterials was the lowest during the entire period.

In addition, it can be seen that the rigidity of the concrete composition of the first example to which nanomaterials were added significantly increased regardless of the composition of the nanomaterials.

Therefore, it can be confirmed that the addition of nanomaterials has the effect of significantly improving the rigidity and durability of concrete over the entire period, and that the effect is further amplified as the period passes.

However, the strength of the concrete composition of the first example in which the nanomaterial of calcium carbonate was added and the concrete composition of the first example in which the nanomaterial containing both silicon dioxide and calcium carbonate were added are almost similar when considering the entire period. , it can be seen that the strength of the concrete composition of the first example in which silicon dioxide nanomaterials were added was significantly greater.

This may mean that the absolute ratio of calcium carbonate and silicon dioxide is more important than the incorporation of both calcium carbonate and silicon dioxide into concrete.

In other words, since the calcium carbonate and the silicon dioxide act independently of each other, the total mass of each has a greater effect on the reinforcing effect of rigidity and durability than the total mass of the calcium carbonate and the silicon dioxide compared to the mass of the concrete. You can see that

This means that the calcium carbonate reinforces the durability and rigidity of concrete through van der Waals' physical method, and the silicon dioxide reinforces the durability and rigidity of concrete through a chemical reaction, so each absolute value is more meaningful than the total mass. It can be interpreted as a factor that exists.

In addition, it can be confirmed that the effect of reinforcing the durability and rigidity of concrete is greater when the nanomaterial is made of silicon dioxide rather than calcium carbonate.

However, when the nanomaterial is composed of calcium carbonate, it does not chemically react with the concrete composition itself, so it has the effect of increasing durability and rigidity while maintaining the physical properties and properties of concrete as much as possible. You can.

As a result, concrete compositions containing nanomaterials have greater durability and rigidity than concrete compositions without nanomaterials, regardless of the composition of the nanomaterials, so they can be actively used in environments where maintenance is frequent, such as roads. As a result, the durability and rigidity of the road are further increased and the number of maintenance can be greatly reduced.

Figure 4 shows the effect of adding nanomaterials to the concrete composition of the second embodiment of the present invention.

The concrete composition of the second embodiment of the present invention may require physical properties as shown in the table above to maintain certain durability and strength even in harsh environments such as roads.

For example, for the above required properties, the diameter of the aggregate should not exceed 13 mm and the rigidity should be maintained at 35 MPa or more. In addition, fluidity must be secured to ensure a slump of 190 mm, and the internal void ratio must be managed within the range of 3 to 6%. The water and binder should be 39 percent, and the fine aggregate percentage may be 58 percent.

The concrete composition of the second embodiment of the present invention basically contains 148 kg/m3 of water, 190 kg/m3 of cement, 57 kg/m3 of fly ash, 133 kg/m3 of blast furnace slag, and 1031 kg of sand so that roads can be paved to maintain durability in the environment. /m3, gravel 764kg/m3. However, latex may be excluded.

When nanoparticles are not added to the concrete composition of the second example mixed in this way, the change in strength over a period of time can be measured, and this can be set as a control group against which the effect of nanomaterials can be compared.

The effect of nanomaterials can be confirmed by measuring and comparing the change in strength over a period of time when nanomaterials are added to the concrete composition of the first example based on the control group.

Specifically, the table shows the change in strength over a specific period of time when nanomaterials were not added to three specimens of the concrete composition of the second example.

It can be seen that the average strength of the concrete of the second example is 34.42 MPa on the 7th day, and that the average strength increases as it hardens to 53.76 MPa on the 28th day.

The above table shows the change in strength over a specific period of time when nanomaterials composed of silicon dioxide were added to three specimens of the concrete composition of the second example at a rate of 2% of the total weight.

It can be seen that the average strength of the concrete of the second example was 36.00Mpa on the 7th day and 63.95Mpa on the 28th day when nanomaterials made of silicon dioxide were added.

In other words, when nanomaterials containing silicon dioxide were added, the strength increased by an average of 4.59% on the 7th day compared to when the nanomaterial was not added, and on the 28th day, the strength increased by an average of 18.97%.

The table above shows the change in strength over a specific period of time when nanomaterials composed of calcium carbonate were added to three specimens of the concrete composition of the second example at a rate of 2% of the total weight.

It can be seen that in the concrete of the second example, when nanomaterials made of calcium carbonate were added, the average strength value was 35.71Mpa on the 7th day, and the average strength value was 56.07Mpa on the 28th day.

In other words, when nanomaterials containing calcium carbonate were added, the strength increased by an average of 3.74% on the 7th day compared to when no nanomaterials were added, and on the 28th day, the strength increased by an average of 4.30%.

However, it can be seen that the rate of increase in strength is lower than when the nanomaterial containing silicon dioxide is added.

The table above shows the change in strength over a specific period when nanomaterials containing both calcium carbonate and silicon dioxide were added to three specimens of the concrete composition of the second example at a rate of 1% of the total weight.

In other words, when nanomaterials containing both calcium carbonate and silicon dioxide were added to the concrete of the second example, the average strength value was 35.94Mpa on the 7th day, and the average strength value was 57.70Mpa on the 28th day. .

That is, when nanomaterials containing both calcium carbonate and silicon dioxide were added, the strength increased by an average of 4.42% on the 7th day compared to when no nanomaterials were added, and on the 28th day, the strength increased by an average of 7.33%. Able to know.

On the other hand, it can be seen that the concrete of the second embodiment, like the concrete of the first embodiment, has a lower rate of increase in strength than when the nanomaterial containing silicon dioxide is added.

Moreover, it can be seen that the trend of further increase in strength compared to when the nanomaterial containing calcium carbonate was added was not confirmed.

Figure 4 is a graph showing the change in intensity continuously measured over a specific period as shown in the table above. Based on the concrete composition of the second embodiment, the x-axis of the graph represents the period, and the y-axis represents the change in rigidity of the concrete composition over time.

Through the graph of FIG. 4, it is possible to see at a glance not only the effect of nanomaterials even when the composition of concrete is different, but also what nanomaterials are composed of that are more effective.

In other words, through the graph in Figure 4, it can be seen whether the effect of nanomaterials can still be proven even if the composition ratio of concrete changes.

Referring to the graph of FIG. 4, since no nanomaterial was added to the concrete composition of the second example mixed at the above specific gravity during a specific period, 2% of the total specific gravity of the nano material was added to the concrete composition of the second example mixed at the above specific gravity. Nanomaterials of the size of silicon dioxide were added, 2% of the total weight of nanosized calcium carbonate nanomaterials were added to the concrete composition of the second example mixed at the above specific gravity, and the first concrete composition mixed at the above specific gravity. The change in rigidity can be seen when a nanomaterial containing 2% of the total weight of nano-sized calcium carbonate and silicon dioxide was added to the concrete composition of the example.

By analyzing the graph, it can be seen that the strength of the concrete composition of the second example without adding nanomaterials was the lowest during the entire period.

In addition, it can be seen that the rigidity of the concrete composition of the second example to which nanomaterials were added significantly increased regardless of the composition of the nanomaterials.

Therefore, it can be confirmed that the addition of nanomaterials has the effect of significantly improving the rigidity and durability of concrete over the entire period, and that the effect is further amplified as the period passes.

However, the strength of the concrete composition of the first example in which the nanomaterial of calcium carbonate was added and the concrete composition of the first example in which the nanomaterial containing both silicon dioxide and calcium carbonate were added are almost similar considering the entire period. , it can be seen that the strength of the concrete composition of the first example in which silicon dioxide nanomaterials were added was significantly greater.

This may mean that the absolute ratio of calcium carbonate and silicon dioxide is more important than the incorporation of both calcium carbonate and silicon dioxide into concrete.

In other words, since the calcium carbonate and the silicon dioxide act independently of each other, the total mass of each has a greater effect on the reinforcing effect of rigidity and durability than the total mass of the calcium carbonate and the silicon dioxide compared to the mass of the concrete. You can see that

This means that the calcium carbonate reinforces the durability and rigidity of concrete through van der Waals' physical method, and the silicon dioxide reinforces the durability and rigidity of concrete through a chemical reaction, so each absolute value is more meaningful than the total mass. It can be interpreted as a factor that exists.

In addition, it can be confirmed that the effect of reinforcing the durability and rigidity of concrete is greater when the nanomaterial is made of silicon dioxide rather than calcium carbonate.

However, when the nanomaterial is composed of calcium carbonate, it does not chemically react with the concrete composition itself, so it has the effect of increasing durability and rigidity while maintaining the physical properties and properties of concrete as much as possible. You can.

As a result, concrete compositions containing nanomaterials have greater durability and rigidity than concrete compositions without nanomaterials, regardless of the composition of the nanomaterials, so they can be actively used in environments where maintenance is frequent, such as roads. As a result, the durability and rigidity of the road are further increased and the number of maintenance can be greatly reduced.

The concrete of the first embodiment and the concrete of the second embodiment can be considered as concrete with significant physical properties, such as differences in the presence or absence of latex. Nevertheless, since it can be seen that both durability and rigidity increase dramatically when nanomaterials are added, it can be concluded that nanomaterials increase both durability and rigidity in concrete compositions.

Furthermore, since the concrete composition of the present invention contains slag aggregate, electric furnace oxide slag, and ferronickel slag, which can replace sand, the van der Waals adhesion effect and chemical reaction between the slag aggregate, electric furnace oxide slag, and ferronickel slag and nanomaterials are increased. It can be interpreted that, unlike regular sand, it has the effect of strengthening stiffness and durability.

As a result, the concrete containing the nanomaterial of the present invention not only implements the functions of eco-friendly concrete, but also guarantees rigidity and durability, so it can be actively used for road paving, etc.

The present invention can be modified and implemented in various forms, and its scope is not limited to the above-described embodiments. Therefore, if the modified embodiment includes elements of the claims of the present invention, it should be considered to fall within the scope of the present invention.

G: Aggregate size
SiO2: Silicon dioxide
CaCO3: Calcium carbonate
N: Nanomaterial

Claims (7)

In a concrete composition containing a three-component cement containing cement, blast furnace slag, and fly ash,
At least one of slag aggregate, electric furnace oxidation slag, and ferronickel slag,
Further comprising a reinforcing material that enhances the rigidity of the concrete composition,
The slag aggregate, the electric furnace oxidation slag, and the ferronickel slag are provided to replace at least a portion of the sand,
The reinforcing material further includes nanomaterials having a nanometer (nm) size, and additional materials added in addition to the nanomaterials,
The nanomaterial includes either calcium carbonate (CaCO3) or silicon dioxide (SiO2),
If the nanomaterial contains the calcium carbonate, the additional material is provided only as an ionic bonding material,
When the nanomaterial includes the silicon dioxide, the additional material is provided only as a single element material,
All of the above nanomaterials are 50 nanometers (nm) or less,
When the nanomaterial includes the calcium carbonate, the ionic binding material includes at least one of magnesium oxide (MgO), silicon dioxide (SiO2), aluminum oxide (Al2O3), and iron oxide (FeO3),
When the ionic binding material includes the magnesium oxide, the magnesium oxide is added in a weight ratio of 0.35% or less based on 100 parts by weight of the total nanomaterial,
When the ionic binding material includes silicon dioxide, the silicon dioxide is added in a weight ratio of 0.1% or less based on 100 parts by weight of the total nanomaterial,
When the ionic binding material includes the aluminum oxide, the aluminum oxide is added at a weight ratio of 0.1% or less based on 100 parts by weight of the total nanomaterial,
When the ionic binding material includes the iron oxide, the iron oxide is added in a weight ratio of 0.1% or less based on 100 parts by weight of the total nanomaterial,
When the nanomaterial includes the silicon dioxide, the single element material includes one or more of titanium (Ti), calcium (Ca), sodium (Na), and iron (Fe),
When the single element material includes titanium, the titanium is added at less than 220 ppm based on the entire concrete composition,
When the single element material contains calcium, the calcium is added at less than 130 ppm based on the entire concrete composition,
When the single element material contains sodium, the sodium is added in an amount of less than 80 ppm based on the entire concrete composition,
When the single element material contains iron, the iron is added in an amount of less than 40 ppm based on the entire concrete composition.



delete According to paragraph 1,
A concrete composition, characterized in that the nanomaterial is provided in a weight of 0.5% to 2% of the total weight of the concrete composition.


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