KR101366174B1 - Ecofriendly cement binder composite - Google Patents

Abstract

The present invention 5 ~ 20wt% cement, blast furnace slag powder 30 ~ 70wt%, fly ash 10 ~ 30wt%, high calcium ash 5 ~ 15wt%, activated binder made of at least one of gypsum, anhydrous gypsum and desulfurized gypsum 3 ~ 7wt It provides an environmentally friendly binder composition comprising%.

Description

Ecofriendly cement binder composite

The present invention relates to an environmentally friendly binder composition for carbon reduction concrete using industrial by-products containing high calcium ash.

Currently, the establishment of a global cooperation system to prevent global warming is in progress, and accordingly, the demand for globalization, green construction, and technological innovation in the field of construction is becoming a hot topic. Carbon emissions, which account for most of Korea's greenhouse gases, was about 490 million tons in 2007, ranking 6th in the OECD and 9th in the world. Of these, construction and transportation account for 43.2%. . In particular, the domestic construction industry accounts for 17% of GDP, and construction materials, which account for 38%, are industrial sectors that consume a large amount of carbon and consume about 25% of national energy consumption, such as cement and steel. .

In 2008, the total carbon generation in Korea was 6.6 billion tons, which is estimated to be about 10% in the concrete industry among the construction materials. Most of the carbon is generated during cement production. About 0.8 tonnes of carbon dioxide is produced in the production of one tonne of cement, more than 60% of which is produced by the decarbonate reaction of limestone in the process.

Commonly used cement mixtures include industrial by-products such as blast furnace slag powder and fly ash, and limestone fine powder. The use of mixtures is a function of carbon due to the reduction of the amount of clinker. It not only reduces emissions, but also improves hydration heat characteristics of concrete and improves durability such as chemical resistance and chlorine ion penetration resistance through high density, and is suitable for producing super flow concrete due to its low specific gravity and appropriate rheological properties.

Industrial by-products such as blast furnace slag powder and fly ash, however, react with calcium hydroxide, which is a hydrate product of lime and cement, to form a stable insoluble compound, but its reactivity is relatively slow, resulting in the initial strength of concrete when used in large quantities. If the cement, which is a Ca ion source, is below a certain level, it may not activate the reactivity of the pozzolanic material, which may cause the strength and durability of the concrete to decrease. In addition, excessively increasing the amount of binder used to increase the strength or decrease the number of units, may result in a poor workability due to the increase in the viscosity of the concrete and the economical efficiency of the structure due to the increase in the cost of concrete.

Therefore, it is necessary to develop carbon-reduced eco-friendly cement by actively responding to the climate change convention and increasing industrial by-products in order to enhance the competitiveness of the cement industry.

The present invention is to provide a binder composition for eco-friendly concrete containing a high ratio of calcium ash and an active binder in a certain ratio in order to improve the strength and durability of the concrete according to the use of a large amount of industrial by-products and the decrease in the amount of cement used.

In particular, blast furnace slag powder and fly ash as the main raw material, and the addition of an activated binder composed of any one of anhydrous gypsum, dihydrate gypsum and desulfurized gypsum in a certain range to significantly improve the early strength reduction due to the use of a large amount of industrial by-products To provide an environmentally friendly binder composition for concrete.

In order to solve the above problems, the present invention, cement 5 ~ 20wt%, blast furnace slag powder 30 ~ 70wt%, fly ash 10 ~ 30wt%, high calcium ash 5 ~ 15wt%, dihydrate gypsum, anhydrous gypsum and desulfurized gypsum It provides an environmentally friendly concrete binder composition comprising 3 ~ 7wt% of the activated binder made of.

In this case, the high calcium ash may be characterized in that the glass lime (CaO) content 20 ~ 60wt%, SO ₃ content is 2 ~ 7wt%, the powder degree 2,000 ~ 5,000 ㎠ / g.

In addition, the blast furnace slag powder is a pulverized blast furnace slag, it may be characterized in that the powder degree is 3,000 ~ 4,500 cm 2 / g.

The binder composition according to the present invention contains a small amount of cement, and contains a large amount of industrial by-products such as high calcium ash, fly ash, blast furnace slag powder, and thus plays a major role in environmental conservation by reducing carbon emissions generated during cement production.

In addition, when the binder according to the present invention is applied to concrete, high calcium ash and gypsum as an activating binder supply a large amount of Ca ions, thereby continually performing the latent hydraulic activation and pozzolanic reaction of blast furnace slag powder and fly ash. Therefore, unlike the existing low cement binder, there is no need to use a large amount of alkali stimulant, thereby preventing workability degradation, rapid freezing and whitening that may occur when using a large amount of alkali stimulant, and improving concrete workability.

Meanwhile, when the binder according to the present invention is applied to concrete, it compensates for the decrease in strength due to the reduction of cement due to the glass lime and SO ₃ present in the high calcium ash and gypsum, and excellent performance in terms of durability such as reduction of heat of hydration and increase of salt resistance. It can be used.

1 is a high calcium ash thermal analysis results table.

The present invention is any one of cement 5 ~ 20wt%, blast furnace slag powder 30 ~ 70wt%, fly ash 10 ~ 30wt%, high calcium ash 5 ~ 15wt% containing free lime (CaO), dihydrate gypsum, anhydrous gypsum and desulfurized gypsum It provides an environmentally friendly concrete binder composition comprising 3 ~ 7wt% of the activated binder made of.

In another aspect, the present invention provides a high calcium ash glass lime (CaO) content of 20 ~ 60wt%, SO ₃ content of 2 ~ 7wt%, powder also provides an environment-friendly concrete binder composition, characterized in that 2,000 ~ 5,000㎠ / g. do.

In another aspect, the present invention is a blast furnace slag fine powder is a pulverized blast furnace slag, provides a binder composition for eco-friendly concrete, characterized in that the powder degree is 3,000 ~ 4,500 cm 2 / g.

In addition, the present invention is a cement, blast furnace slag powder, high calcium ash, the binder component of the binder composition SO ₃ Is included, the content of free lime for the whole of the binder composition is provided with an environmentally-friendly concrete binder composition, characterized in that 1 to 8wt%, SO ₃ content is 4 to 8wt%.

Hereinafter, look at the binder composition of the present invention, to explain the characteristics of the present invention according to a specific experiment according to the powder ratio proposed in the present invention.

1. The present invention Binders  Composition

(1) Cement

Cement in the binder composition of the present invention is a composition generally used as a component of the binder required for the production of concrete. The main components of the cement are CaO, SiO ₂ , Al ₂ O ₃ and Fe ₂ O _3, etc. These are the basis for estimating and judging the composition of the main minerals that govern the action of hydration, condensation, hardening, etc. do. The cement causes a hydration reaction with water, thereby allowing the coagulation and curing reactions to proceed. Representative products of the hydration reaction proceeding at room temperature and atmospheric pressure are CSH hydrate (calcium silicate hydrate) and Ca (OH) ₂ (calcium hydroxide).

The general binder composition is composed mostly of cement, but the binder composition according to the present invention is a low cement binder composition containing 5 to 20wt% of cement, which emits a large amount of carbon dioxide as decarbonated limestone, so that the amount of cement can be significantly reduced. It is environmentally friendly. The point of containing 5 ~ 20wt% of cement is less than 5wt%, the lack of a main binder that expresses the strength of concrete and the lack of a source of Ca ions that activates the reaction of other mixtures. May occur, the carbon of which is the object of the present invention if more than 20wt% This is because the heat of hydration of the binder is increased and the probability of temperature cracking when applied to concrete increases because it does not meet the purpose of reducing the generation amount.

(2) Blast furnace slag Fine powder

The blast furnace slag powder is an industrial by-product generated in steel mills. Generally, the blast furnace slag powder does not reach the fly ash, but it has a certain effect of reducing the heat of hydration. It is preferable that content of blast furnace slag fine powder in the total weight ratio of the binder composition of this invention is 30-70 wt%. When the content of blast furnace slag powder is 30wt% or less, the content of main material which plays a major role in early strength expression decreases as the amount of cement used decreases, so that strength expression is insufficient, and when the content of blast furnace slag powder is 70wt% or more, the viscosity of the binder increases. This is because not only the concrete workability is lowered, but also the probability of cracking is increased due to the increase of drying and self shrinkage due to high powder.

In particular, the blast furnace slag fine powder is preferably pulverized powder of 3,000 ~ 4,500 cm 2 / g, when the powder is less than 3,000 cm 2 / g, the particles are coarse to delay the latent hydraulic hardness to adversely affect the strength development When the degree of powder is 4,500 cm 2 / g or more, because the powder of the binder is excessively high and may cause a decrease in workability of the concrete as the viscosity increases.

(3) Fly ash

Fly ash (fly ash) is preferably in the content of 10 ~ 30wt% in the environmentally friendly binder to be developed through the present invention. In general, fly ash is not hydrophobic in itself, but the silica component reacts slowly with calcium hydroxide, which is a hydration product of lime and cement, to form a stable insoluble compound and to harden it. It is preferable that it is 10-30 wt%.

(4) High calcium ash

High calcium ash is an industrial by-product of cogeneration and papermaking. Small and medium-sized cogeneration plants have very different chemical characteristics than fly ash (KS L 5405) generated from thermal power plants because the combustion temperature is relatively low at 850 ° C, unlike general thermal power plants, to minimize emissions of nitric oxide and sulfur oxides. have. In the papermaking process, sludge containing a large amount of fine limestone powder is generated, and ash is collected in the electrostatic precipitator during incineration of the sludge. This occurs during the process of maintaining the combustion temperature at about 850 ℃ to prevent the release of nitric oxide in the cogeneration plant, and spraying ammonia, so that a high content of free lime (CaO) exists, SO ₃ and MgO It is characterized in that it contains a large amount compared to the general fly ash. This difference can be seen in [Table 1], which is a comparison table comparing the characteristics of the thermal power plant refined fly ash and the high calcium ash used in the present invention.

Item Fired power plant refined fly ash  High calcium ash Combustion temperature About 1,350 DEG C About 850 ° C Desulfurization equipment Separate wet desulfurization facility operation Desulfurization of limestone Denitrification facility Separate denitrification facility operation Low combustion temperature and ammonia spray Major Chemical Components SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ SiO ₂ , Al ₂ O ₃ , MgO, Free CaO (40 to 60 wt%), SO ₃ (3 to 7 wt%),

The binder composition of the present invention contains 5 ~ 15wt% of high calcium ash generated in the cogeneration plant and the papermaking process to compensate for the decrease in strength according to the reduction of the amount of cement used, in particular the high calcium ash 20 ~ 60wt%, SO ₃ Is preferably contained at 2 to 7wt%. Ca ions are sufficiently supplied through the content of high calcium ash, so that the latent hydrocurable and pozzolanic reactions of blast furnace slag powder and fly ash can be continuously performed, thereby promoting excellent long-term strength expression and durability improvement of concrete.

The glass lime plays a major role in the strength expression by contributing to the pozzolanic reactivity of the blast furnace slag powder and fly ash, such as fly ash, when less than 20wt%, insufficient strength expression due to the lack of hydration products by the pozzolanic reaction of the mixture In case of more than 60wt%, Ca ions are excessively generated due to the rapid reaction of glass lime, which delays the hydration reaction, resulting in delayed strength expression.

In addition, the content of SO ₃ contained in the high calcium ash is preferably in the range of 2 to 7 wt%. Like glass lime, SO ₃ promotes the reactivity of the cement and the mixed material, thereby effectively acting at early strength, but in the range of 2 to 7 wt%. This is because when the hydration product is insufficient and the hydration retardation action is reduced the strength expression of the cured product.

On the other hand, the powdery range of high calcium ash is preferably in the range of 2,000 to 5,000 cm 2 / g. If it is 2,000 cm 2 / g or less, when coarse particles remain unreacted until long-term age, the expansion of the pressure of the lime caused by the late reaction of free lime It may be a factor causing cracks in the structure, when the 5,000 ㎠ / g or more there is a fear that the workability of concrete and the change over time due to the rapid reaction of high calcium ash initially increases.

(5) activation Binders

The activated binder is composed of at least one of dihydrate gypsum, anhydrous gypsum, and desulfurized gypsum. In the present invention, the content of the activated binder is 3-7 wt%. In general, although gypsum acts as a coagulation retardant to control the initial rapid reaction of cement in cement, gypsum used as an active binder in the present invention promotes latent hydraulic properties of blast furnace slag powder because the present invention includes a large amount of mixture. This is because it plays a key role in securing initial workability and strength by reacting with glass lime which causes rapid reaction with high heat generation. If the content of the activated binder is less than 3wt%, the strength of the mixture is insufficient due to the lack of SO ₃ content, the strength expression is insufficient, and if more than 7wt% the strength expression is delayed due to excessive SO ₃ 3 ~ proposed in the present invention It is preferred to include 7 wt% of the activated binder.

(6) full Binders  Contained in the composition Glass lime  Content and SO ₃ Content ratio

In particular, in the present invention, the high calcium ash is contained in the high calcium ash of the binder composition, and the cement, the blast furnace slag powder, the high calcium ash, and the active binder is partially contained SO ₃ contained in the high calcium ash content and SO ₃ Not only the content ratio but also the free lime and SO ₃ The content ratio is also important.

It is preferable that the content of free lime is 1 to 8 wt% and the SO ₃ content is 4 to 8 wt% based on the total amount of the binder composition. Cement contains about 2.5wt% of SO ₃ in cement, blast furnace slag powder contains about 3wt%, and activated binders such as gypsum contain about 40 ~ 53wt% of SO ₃ . It is effective for compressive strength and durability to apply _{3 to} the content of ₃ to 4 ~ 8wt%, glass lime content of 1 ~ 8wt%.

2. The present invention Binders  Test on the composition

(1) Formulation conditions for the test of the present invention

The binder composition of the present invention is to lower the cement content contributing to the strength expression, the main raw material of the blast furnace slag powder and fly ash, mixed with an active binder composed of at least one of anhydrous gypsum, dihydrate gypsum and desulfurized gypsum and high calcium ash Ca Enough ions are supplied.

In particular, to promote the reactivity of the mixture includes a high calcium ash and an activated binder gypsum. Glass lime, the main component of high calcium ash, delays the strength development slightly initially, but plays a major role in the development of long-term strength. SO ₃ contained in gypsum promotes the activation of latent hydraulic properties of blast furnace slag powder, which is excellent for early strength development. Will be used. However, if the content of high calcium ash and gypsum is insufficient or excessive, the proper level of performance can not be achieved, and this can be adjusted to an appropriate mixing ratio in consideration of the chemical composition of high calcium ash and gypsum. This may be insufficient, and the strength development time may be excessively delayed to satisfy the performance to be obtained in the present invention.

Therefore, the present invention provides a binder composition for concrete, in which anhydrous gypsum is mixed with cement, blast furnace slag fine powder, fly ash, high calcium ash and an activated binder. In the case of using the binder composition of the present invention, the cement composition according to KS L ISO 679 Tests were conducted to confirm that they exhibited moderate good early strength and long term strength.

Table 2 below shows powder blending conditions of Examples and Comparative Examples belonging to the present invention.

Powder compounding condition (wt%) Chemical composition (wt%) OPC SP3 SP4 SP7 FA HA1 HA2 GY CaO content SO3 content Example 1 10 60 20 5 5 1.59 5.78 Example 2 10 55 20 10 5 3.18 5.85 Example 3 10 55 20 10 3 3.18 4.84 Example 4 10 55 20 10 5 2.91 5.41 Example 5 10 55 20 10 5 3.18 5.98 Comparative Example 1 10 70 20 - 3.17 Comparative Example 2 10 70 20 - 3.34 Comparative Example 3 10 70 20 - 3.03 Comparative Example 4 10 60 20 10 3.18 3.31 Comparative Example 5 10 60 20 10 2.91 2.89 Comparative Example 6 10 67 20 3 - 4.69 Comparative Example 7 10 65 20 5 - 5.71 Comparative Example 8 10 55 20 5 10 1.59 8.32 * OPC: Cement
* SP3: Blast Furnace Slag Powder Powder 3000cm2 / g
* SP4: Blast Furnace Slag Powder Powder 4000cm2 / g
* SP7: Blast Furnace Slag Powder 7000cm2 / g
* FA: Fly Ash
* HA1, 2: high calcium ash
* GY: Natural Anhydrous Gypsum

Table 3 below shows the results of high calcium ash chemical analysis.

Chemical composition (weight ratio) Powder figure
(Cm 2 / g) SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ HA1 27.60 12.95 6.85 35.25 5.98 5.57 4848 HA2 25.50 13.28 5.42 45.70 5.27 1.29 2150

In the present invention, as shown in the chemical analysis results of Table 3, the test was performed using two samples having different CaO contents.

1 is a high calcium ash thermal analysis results table. As shown in the thermal analysis results of FIG. 1, the endothermic peak due to calcium hydroxide near 450 ° C. and the endothermic peak due to decarbonated acid near 750 ° C. appear, and in the case of HA1, the content of free lime present as pure CaO is about It is 33wt%, it can be seen that HA2 contains about 28wt% level of free lime.

(2) compressive strength

In order to confirm the compressive strength of the mortar using the present invention, Examples 1 to 5 shown in [Table 2] were compared and evaluated for the compressive strength expression characteristics of the present invention according to KS L ISO 679 and Comparative Examples 1 to 8.

Mortar Compressive Strength (MPa) 3 days 7 days 28th Example 1 13.2 28.2 36.0 Example 2 12.1 26.6 36.9 Example 3 16.4 26.6 35.5 Example 4 16.9 25.3 33.5 Example 5 10.7 25.6 34.2 Comparative Example 1 9.4 15.4 28.2 Comparative Example 2 9.3 14.4 25.1 Comparative Example 3 11.0 16.0 23.9 Comparative Example 4 10.3 17.2 29.3 Comparative Example 5 9.6 17.2 28.4 Comparative Example 6 14.1 20.3 25.0 Comparative Example 7 16.1 24.1 27.8 Comparative Example 8 11.2 19.4 26.7

Table 4 shows the mortar compressive strength measurement results using the mixing conditions of the examples and comparative examples presented in the above [Table 2].

In the case of the embodiment of the present invention, the strength was excellent from the early stage, the early strength of 25MPa or more at 7 days of age to express the early strength superior to Comparative Examples 1 to 3 without the addition of high calcium ash and gypsum. In addition, although the cement content is reduced, excellent results are shown in comparison with the comparative example even in long-term strength expression. This is the result of the formation of high sulfate in the early hydration when gypsum is added, which plays a major role in the early strength expression.Afterwards, the free lime contained in high calcium ash reacts with blast furnace slag powder and fly ash and pozzolanic reaction to improve long-term strength expression. to be.

In addition, as shown in Comparative Examples 4 to 8, when out of the range of the binder composition belonging to the scope of the present invention, the compressive strength expression performance to be obtained in the present invention by reducing the initial strength expression and reduced long-term strength expression due to the lack of cement content It can be confirmed that it can not be obtained, in particular, in the case of Comparative Example 8 can be confirmed that the strength expression is poor until the 28 days of age after the early strength delay, according to the out of the scope of the present invention by excessive addition of gypsum.

Concrete mixture and concrete properties prepared using the binder is as shown in Table 5 below.

Formulation Name W / B
(vol%) S / a
(vol%) Binder
(kg / m ³ ) WR / B
(wt%) slump flow
(mm) Air
(vol%) Concrete Compressive Strength (MPa) 3 days 7 days 28th Example 1 27.5 45.0 550 0.75 640 3.2 20.6 40.3 58.0 Example 2 0.75 660 3.3 19.4 41.1 59.6 Example 3 0.75 680 3.0 19.8 38.7 56.9 Example 5 0.70 650 3.1 18.2 35.1 52.8 Comparative Example 1 0.75 620 2.9 16.0 29.2 33.6 Comparative Example 2 0.75 650 3.0 15.0 26.8 30.2 Comparative Example 3 0.85 630 2.6 21.4 34.4 45.3

(W / B = water binder, S / a = fine aggregate ratio, Binder = binder, WR = water reducing agent)

Table 5 shows the experimental results for the concrete blended using the binder composition provided by the present invention. At this time, the water binder ratio is the volume% of water compared to 100% by volume of the binder, and the aggregate aggregate means the volume% of the fine aggregate relative to 100% by volume of the total aggregate, which is the coarse aggregate and the fine aggregate. The units of the binding agent will represented by the weight (kg) per unit volume per 1m ³ of concrete, a water-reducing agent is a weight% (wt%), based on the binder 100 weight% (wt%), air amount is based on a concrete total 100% by volume It is expressed in one volume percent.

When comparing Example 3 and Comparative Example 2 in the first [Table 5] in the case of Example 3 using the binder of the present invention containing a high calcium ash under the same conditions it is confirmed that the high slump flow value can be improved workability Can be.

In addition, when comparing the Example 5 and Comparative Example 2, the slump flow is 650mm in Comparative Example 2 containing the water reducing agent 0.75% by volume in the same conditions, while in Example 5, because the water reducing agent is contained 0.70% by volume, When the present invention is applied, the same slump flow value can be obtained even if the content of the reducing agent is low. This is because the glass lime present in the high calcium ash delays the hydration reaction of the cement early to improve the working performance.

On the other hand, the compressive strength characteristics of concrete also shows that the embodiment exhibits superior strength expression characteristics from the early stage compared to the comparative example, it can be confirmed that it is maintained until the age of 28 days, except for Comparative Example 3 in which the blast furnace slag powder of the high powder degree is applied. It was confirmed that strength expression was low from 3 days of age, so that the strength expression was insufficient until 28 days of age.

Comparative Example 3 exhibited excellent strength expression characteristics initially due to the densification of concrete structure due to the high powder density of blast furnace slag powder, but it was confirmed that the strength expression was poor at 28 days due to the lack of cement content for the reaction of pozzolanic materials.

In addition, the mortar compressive strength of Example 4 was significantly maintained as compared to Comparative Example 8 on the 28th day when comparing the Example 4 and Comparative Example 8 with respect to the effect of the content ratio of glass lime and SO ₃ of the entire binder composition This can be confirmed through.

Therefore, in the case of using the binder composition of the present invention also in the concrete properties, the slump flow is relatively increased, showing excellent work performance, and the compressive strength also shows the characteristics of excellent strength expression from 3 days old to 28 days old. It can be seen that is maintained.

(3) Salt resistance

The durability evaluation according to the concrete salt resistance was evaluated by calculating the salinity diffusion coefficients for some of the examples and comparative examples of the above [Table 2]. Table 6 shows the calculation results of the salinity diffusion coefficients of the 7th and 28th days of the Examples 1 and 2 and Comparative Examples 1 and 2.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Salinity Diffusion Coefficient
(10 ^-12 m ² / s) 7 days 10.2 9.8 12.5 13.6 28th 2.8 2.4 6.6 7.3

In the seventh day, relatively large amounts of industrial by-products are used in comparison with cement, so that Examples 1 and 2 and Comparative Examples 1 and 2 do not show significant differences, but Examples 1 and 2 are slightly lower than Comparative Examples 1 and 2. It shows salinity diffusion coefficient and shows excellent durability from the beginning, and in 28 days, it was confirmed that Examples 1 and 2 showed superior durability compared to Comparative Examples 1 and 2 due to continuous densification of concrete structure by continuous pozzolanic reactivity. Can be.

As described above, the binder composition for eco-friendly concrete according to the present invention is eco-friendly because it brings the effect of reducing carbon by using industrial by-products, and has excellent characteristics compared to conventional binders in terms of compressive strength and salt resistance.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Therefore, the claims of the present invention include modifications and variations that fall within the true scope of the invention.

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Claims (4)

Cement 5 ~ 20wt%, blast furnace slag powder 30 ~ 70wt%, fly ash 10 ~ 30wt%, high calcium ash 5 ~ 15wt%, hydrated gypsum, anhydrous gypsum and desulfurized gypsum comprising 3 ~ 7wt% of one or more activated binder But
The high calcium ash is characterized in that the glass lime (CaO) content 20 ~ 60wt%, SO ₃ content is 2 ~ 7wt%, powder degree 2,000 ~ 5,000 ㎠ / g, The blast furnace slag powder is finely ground blast furnace chain slag As one, the binder composition for eco-friendly concrete, characterized in that the powder degree is 3,000 ~ 4,500 cm 2 / g.
delete delete In claim 1,
Cement, blast furnace slag powder, high calcium ash, the activated binder of the binder composition is SO ₃ Contains,
The content of free lime for the whole of the binder composition is 1 ~ 8wt%, SO ₃ content of 4 ~ 8wt% eco-friendly concrete binder composition, characterized in that.

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