KR101007928B1 - Premix admixture composition for cement replacement by improving the physical properties of blast furnace slag powder and binder composition for concrete comprising the same - Google Patents

Abstract

The present invention provides a premix admixture composition which optimally improves the intrinsic properties of the blast furnace slag fine powder by appropriately formulating the blast furnace slag fine powder, the limestone fine powder and the gypsum so that it can be preferably used as a substitute for cement, and for the concrete having appropriately formulated the admixture composition. A binder composition is disclosed.

Cement substitute premix admixture composition according to the present invention, blast furnace slag fine powder 60 to 80% by weight; Limestone high fine powder 15-30% by weight; And, gypsum 5 ~ 10% by weight; The limestone high fine powder, calcium carbonate (CaCO ₃ ) occupies 75 ~ 90% by weight as the main component, while the powder degree of 6,000 ~ 12,000㎠ / g and the average particle size of 4 It is characterized by having a density of ˜6 μm and a density of 2.6-7 g / cm 3.

The binder composition for concrete according to the present invention is characterized in that the composition by substituting 10 to 35% by weight of the premix admixture composition for cement replacement.

Blast furnace slag, limestone fine powder, gypsum, admixture, initial strength

Description

Premix admixture composition for cement replacement and concrete binder composition using the same by improving the properties of blast furnace slag fine powder

The present invention provides a premix admixture composition which optimally improves the intrinsic properties of the blast furnace slag fine powder by appropriately formulating the blast furnace slag fine powder, the limestone fine powder and the gypsum so that it can be preferably used as a substitute for cement, and for the concrete having appropriately formulated the admixture composition. A binder composition is disclosed.

In the manufacture of concrete, blast furnace slag powder, fly ash, and other natural pozzolanic materials are commonly used as admixtures. Admixtures contribute to economics as well as resource recycling because they replace some of the relatively expensive cement by industrial by-products. In addition, it has been found to contribute to the improvement of durability, such as by developing strength, increasing chemical resistance, and reducing heat of hydration of concrete, and thus the admixture is a useful material for producing functional concrete, and its performance has been increasing.

Among various admixtures, blast furnace slag fine powder has been widely used because of its improved chemical resistance, control of temperature rise by heat of hydration of concrete, inhibition of alkali aggregate reaction, resistance to seawater and long-term strength.

However, when the blast furnace slag powder comes into contact with water, the impermeable acidic film surrounds the particles on the surface of the blast furnace slag particles, thereby inhibiting the hydration reaction. Therefore, when the blast furnace slag powder is used, the initial hydration expression rate is significantly lowered. The characteristic of low intensity expression at low temperature is shown. Such a characteristic becomes a factor that inhibits the active use of blast furnace slag fine powder.

Meanwhile, in the process of crushing and transporting raw materials during cement production, scattering dust (kilndust) is generated along with the flow of air, and the scattering dust is collected through a separate dust collector and then re-introduced into the manufacturing process. . However, since 90% or more of the cement raw material is composed of limestone, the main component is also limestone fine powder (CaCO ₃ ), which is a very fine particle. Impede the flow or increase adhesion with some volatiles, reducing the efficiency of the installation.

Then, it is desirable to collect and remove the fugitive dust generated during the cement manufacturing process in order to improve the efficiency of cement production and cement productivity, and furthermore, if the collected fugitive dust can be recycled, it would be preferable in terms of resource recycling.

Accordingly, the present inventors have studied the recycling method of fly ash dust, and as a result, the study on the availability of fly ash (kilndust) as a cement admixture, and filed and registered it as a patent application No. 10-2001-0008806 . However, since patent application No. 10-2001-0008806 only remains to examine the availability of fugitive dust as a cement admixture, practical research on the effective use of fugitive dust is needed for the active use of fugitive dust. Situation. In this situation, the present inventors have developed the present invention by conducting a study on the optimum blending range of fugitive dust.

The present invention was developed in order to improve the above-mentioned problems, and in order to optimally improve the physical properties of the blast furnace slag powder, the premix admixture composition for cement replacement using the limestone high powder in an optimum combination ratio, and the admixture composition are preferably substituted. There is a technical problem in providing a binder composition.

In order to solve the above technical problem, the present invention, blast furnace slag fine powder 60-80% by weight; Limestone high fine powder 15-30% by weight; And, gypsum 5 ~ 10% by weight; The limestone high fine powder, calcium carbonate (CaCO ₃ ) occupies 75 ~ 90% by weight as the main component, while the powder degree of 6,000 ~ 12,000㎠ / g and the average particle size of 4 It provides ˜6 μm and the density is 2.6-7 g / cm 3 to provide a premix admixture composition for cement replacement.

In addition, the present invention provides a binder composition for concrete, characterized in that the composition by substituting 10 to 35% by weight of the above-mentioned cement substitute premix admixture composition.

According to the present invention, the following effects can be expected.

First, it is possible to maximize the utilization of the blast furnace slag powder as a cement replacement because it can improve the problems of lowering initial strength and low temperature characteristics while maintaining the advantages of the blast furnace slag fine powder. In particular, while using the blast furnace slag fine powder as a main component can provide a miscible material that can secure sufficient initial strength even under low temperature curing conditions. Therefore, using the admixture according to the present invention can provide a concrete of excellent quality at multiple angles.

Second, the limestone high fine powder, which is one of the raw materials, is proposed as an industrial by-product, so it can not only produce concrete economically while recycling resources, but also protect the environment.

Cement substitute premix admixture composition according to the present invention, blast furnace slag fine powder 60 to 80% by weight; Limestone high fine powder 15-30% by weight; And, 5 to 10% by weight of gypsum.

Blast furnace slag powder is generally excellent in long-term strength, and when used in combination with cement has been used in the existing ready-mixed concrete because of the cost reduction effect and excellent reactivity, the present invention utilizes the same characteristics as it is. However, the blast furnace slag powder has a disadvantage in that the initial strength falls, this disadvantage is compensated by using in combination with limestone high powder and gypsum.

The blast furnace slag fine powder in the admixture composition according to the present invention accounts for 60 to 80% by weight, and this content range is most preferably determined as a range through the following experimental example. In other words, when the blast furnace slag powder is 60% by weight or less, the durability and long-term strength performance, which are advantages of the blast furnace slag powder, are not significantly highlighted, and the limestone high powder is relatively increased, and thus the initial fluidity decreases, and the blast furnace slag powder is 80 wt%. If it is more than%, the effect of improving the initial strength of the blast furnace slag fine powder is insufficient and the effectiveness is inferior.

Limestone fine powder is composed of calcium carbonate (CaCO ₃ ) 75-90% by weight, the powder of 6,000 ~ 12,000 ㎠ / g, the average particle diameter of 4 ~ 6㎛, density 2.6 ~ 7g / ㎠, SiO ₂ , It is characterized by including trace components such as Al ₂ O ₃ , Fe ₂ O ₃ , MgO, SO ₃ , K ₂ O, Na ₂ O (see Table 3 below). Such limestone fine powder exhibits the effect of promoting the initial hydration of the blast furnace slag fine powder by synergistic action by the fine powder filling effect and a small amount of alkali-stimulating component.

In particular, the present invention proposes to use a high concentration of limestone powder collected by the bag filter of fly ash dust generated in the grinding and conveying process of the raw material in the cement manufacturing process. If the limestone fine powder is obtained from limestone ore, the cost increase will be inevitable due to the process of grinding the limestone ore into the fine powder, but in the present invention, the limestone fine powder is obtained by collecting fugitive dust that acts adversely in the cement manufacturing process. Rather, it is possible to reduce costs and to expect resource recycling.

Limestone high fine powder in the admixture composition according to the present invention, the blast furnace slag fine powder in the admixture composition according to the present invention occupies 15 to 30% by weight, and this content range is most preferably determined as a range through the following experimental example. In other words, when the limestone high fine powder is 15 wt% or less, the initial strength improvement effect is lowered by the filling effect, and when the limestone high fine powder is 30 wt% or more, problems of fluidity decrease and strength decrease due to the increase of the powder level occur.

Gypsum serves as a source of SO ₄ ^2- ions in the production of hydration products (ethrinzite) and acts as a stimulator for blast furnace slag fine powder.

In the admixture composition according to the present invention, the gypsum occupies 5 to 10% by weight, and if it is 5% by weight or less, the role of the stimulator of the blast furnace slag powder is insufficient, and the initial strength is improved. It is unfavorable because of the increase in long-term strength due to over-addition.

The premix admixture composition consisting of the above three types of blast furnace slag powder, limestone high powder and gypsum is preferably substituted with 10 to 35% by weight of the total binder, which is economical formulation and initial strength of the blast furnace slag powder. For improvement. In other words, when the amount of admixture of the admixture according to the present invention is 10% by weight or less, the amount of admixture of the blast furnace slag fine powder becomes too small, so that the characteristics and advantages of the blast furnace slag fine powder are not sufficiently obtained, resulting in an uneconomical mixture and the amount of admixture according to the present invention. If the weight is more than 35% by weight, the limestone high fine powder is relatively increased, so that the change in fluidity over time is not only large, but also the initial strength and the long-term strength after 28 days also decrease. Here, "binder" means a powder in which cement and various admixtures are combined, and the admixture composition according to the present invention is included in the binder as a kind of admixture for concrete. Such admixture composition can be directly applied to the production of ready-mixed type concrete, in which the premix admixture composition is pre-mixed and put into one silo.

Hereinafter, look at whether the admixture composition according to the present invention can be used as a cement substitute admixture based on the experimental example. However, the following experimental examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Experimental Example 1] Mortar Quality Characteristics Test for Derivation of Desirable Composition of Admixtures

(1) admixture composition materials

①Blast furnace slag fine powder

Chemical and physical properties of the blast furnace slag fine powder used in the present experimental example are as shown in Table 1 and Table 2.

Chemical Properties of Blast Furnace Slag Powders ingredient LOI SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ K ₂ O Na ₂ O SUM content(%) 0.20 34.41 15.80 1.41 40.02 5.51 2.20 0.40 0.05 100

Physical Properties of Blast Furnace Slag Powders division Activity index basicity Cl density Specific surface area
(Cm 2 / g) 7 days 28 days 91 days KS standard 55 ↑ 75 ↑ 95 ↑ 1.6 ↑ 0.02 ↓ 2.80 ↑ 4,000 ~ 6,000 Slag powder 70 94 108 1.83 0.01 2.91 4,430

② limestone fine powder

Limestone high fine powder used in this Experimental Example is a dust collection of dust scattered in the process of crushing and transporting raw materials in the cement manufacturing process with a bag filter, and has the chemical properties as shown in the following [Table 3]. It is 7,850 cm <2> / g.

Chemical Properties of Limestone Fine Powder ingredient Ignition loss SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ K ₂ O Na ₂ O SUM content(%) 36.50 10.39 3.31 2.23 44.78 1.52 0.64 0.62 0.01 100

③ Gypsum (CaSO ₄ 2H ₂ O)

Gypsum used in the present experimental example has the chemical properties as shown in the following [Table 4] and the powder degree (Blaine) is 4,760 cm 2 / g level.

Chemical Properties of Gypsum ingredient LOI SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ K ₂ O Na ₂ O SUM content(%) 2.49 2.01 0.79 0.46 43.66 0.73 49.62 0.17 0.06 100

(2) Experimental method

Experimental plan was established to derive the optimal combination factor of the admixture composition according to the present invention with the above materials. That is, as shown in the following [Table 5] and [Table 6], SBF1 and MBF1, SBF1 and MBF1 in which plain and admixtures using only ordinary portland cement were replaced with blast furnace slag fine powder (BFS) by 25% and 50%, respectively Experimental plans for SBF2 ~ 8 and MBF2 ~ 8 were prepared by adjusting the admixture with limestone fine powder and gypsum.

Meanwhile, the mortar test specimen was manufactured and cured according to ISO 679 (Method of testing cement- Determination of strength).

Mortar formulation with 25% substituted admixture division cement
(g) sand
(g) water
(g) Admixture
(g)
Admixture Composition Ratio (%) Blast furnace slag
Fine powder Limestone
Fine powder gypsum Plain 450 1,350 225 0 0 0 0 S
(R =
25%)
BF1 337.5 1,350 225 112.5 100 0 0 BF2 337.5 1,350 225 112.5 75 15 10.0 BF3 337.5 1,350 225 112.5 65 25 10.0 BF4 337.5 1,350 225 112.5 60 30 10.0 BF5 337.5 1,350 225 112.5 70 25 5.0 BF6 337.5 1,350 225 112.5 70 24 6.0 BF7 337.5 1,350 225 112.5 70 23 7.0 BF8 337.5 1,350 225 112.5 70 22 8.0 Cement: Class 1 Common Portland Cement
Sand: ISO Standard Yarn
Water: Tap water specified in KS F 4009

Mortar formulation with 50% substituted admixture division cement
(g) sand
(g) water
(g) Admixture
(g)
Admixture Composition Ratio (%) Blast furnace slag
Fine powder Limestone
Fine powder gypsum Plain 450 1,350 225 0 0 0 0 M
(R =
50%)
BF1 225.0 1,350 225 225.0 100 0 0 BF2 225.0 1,350 225 225.0 75 15 10.0 BF3 225.0 1,350 225 225.0 65 25 10.0 BF4 225.0 1,350 225 225.0 60 30 10.0 BF5 225.0 1,350 225 225.0 70 25 5.0 BF6 225.0 1,350 225 225.0 70 24 6.0 BF7 225.0 1,350 225 225.0 70 23 7.0 BF8 225.0 1,350 225 225.0 70 22 8.0 Cement: Class 1 Common Portland Cement
Sand: ISO Standard Yarn
Water: Tap water specified in KS F 4009

(3) Experimental results

As a result of evaluating the physical properties of the mortar according to the combination of [Table 5] and [Table 6], it was confirmed as shown in [Table 7].

Mortar Property Evaluation Results division Mortar Property Evaluation Results Flow
(Mm) Flexural strength (N / ㎡) Compressive strength (N / ㎡) 1 day 3 days 7 days 28 days 91 days 1 day 3 days 7 days 28 days 91 days Plain 82.5 3.9 5.8 6.9 8.3 8.9 14.3 25.8 33.7 50.0 55.8 SBF1 82.3 2.7 5.1 6.7 8.6 8.6 8.8 22.1 34.0 56.5 56.7 SBF2 76.6 3.7 6.6 8.3 9.5 9.8 13.6 29.4 37.1 53.0 63.5 SBF3 79.7 4.6 6.1 8.7 9.5 9.5 14.5 27.3 41.4 52.0 58.8 SBF4 81.5 4.1 6.6 8.6 9.5 9.8 13.4 28.9 44.4 51.2 55.8 SBF5 83.5 4.3 6.4 8.0 9.0 9.4 14.0 26.9 44.3 49.3 52.4 SBF6 81.9 4.4 5.7 7.1 9.3 9.7 14.9 27.5 43.3 46.9 51.3 SBF7 83 3.8 5.8 8.1 9.2 9.2 12.9 27.1 42.3 47.2 55.0 SBF8 83.5 3.8 5.7 8.0 8.9 9.2 13.2 25.1 43.8 45.8 53.8 MBF1 90.8 2.1 4.7 5.8 8.4 10.4 7.2 17.0 34.1 54.9 62.4 MBF2 85.4 2.4 5.5 7.5 9.8 10.7 7.9 21.6 38.7 52.8 58.3 MBF3 83.6 2.2 5.2 7.3 9.6 9.8 7.8 22.0 32.4 49.4 56.2 MBF4 82.5 2.2 5.5 7.0 10.1 10.5 7.7 22.4 31.7 49.5 55.6 MBF5 78.9 2.3 4.7 7.1 9.2 10.3 7.4 20.5 29.1 51.5 51.1 MBF6 83.5 2.4 5.3 6.5 9.9 10.0 7.7 21.6 28.5 49.7 56.9 MBF7 90.1 2.2 5.3 7.7 9.0 9.8 7.8 21.3 37.0 48.5 55.2 MBF8 89.9 1.8 5.1 7.7 8.5 9.9 6.5 21.8 36.3 47.1 52.8

On the other hand, the physical properties of the mortar as shown in the above [Table 7] summarized as shown in Figs.

Figure 1 shows the flow value, the overall mortar flow tends to be larger when the substitution ratio is 50% than when the substitution ratio of the admixture is 25%. However, in some cases, it is confirmed that sufficient fluidity is secured, so it will not be a problem in use.

Figure 2 shows the mortar bending strength by age, SBF3 was the most excellent initial strength improvement effect compared to plain as well as all ages, and in other cases was shown to be lower than plain at some ages.

Figure 3 shows the mortar compressive strength by age, SBF3 is superior to plain at all ages, and in other cases it was shown to be lower than plain at some ages.

In conclusion, SBF3 is the only flexural strength and compression at early age and medium and long-term age. The strength was higher than the plain level. Thus, the present invention proposes a mixed material composition composed of 60 to 80% by weight of blast furnace slag fine powder, 15 to 30% by weight of limestone high powder, and 5 to 10% by weight of gypsum in a preferred optimum range.

[Experimental Example 2] Mortar quality characteristics test for deriving desirable amount of admixture

(1) Experimental method

As the mixed material composition SBF3 of the optimum composition derived in [Experimental Example 1], an experimental plan was established to derive the preferred amount of use (substitution amount) of the mixed material composition according to the present invention. That is, as shown in the following [Table 11], ABF1, BBF1 and CBF1, admixtures substituted with 10%, 20%, and 30%, respectively, using plain plain admixture using only ordinary portland cement as blast furnace slag fine powder alone, [Experimental Example] Experimental plans for ABF2, BBF2, and CBF2 substituted with 10%, 20%, and 30%, respectively, were made with the mixed composition SBF3 having the optimum composition derived from 1].

On the other hand, the experimental materials and the test method were the same as in [Experimental Example 1].

Mortar division cement
(g) sand
(g) water
(g) Admixture
(g) Admixture Ratio (%) Blast furnace slag
Fine powder Limestone
Fine powder gypsum Plain 450 1,350 225 0 0 0 0 A
(R = 10%) BF1 405.0 1,350 225 45.0 100 0 0 BF2 405.0 1,350 225 45.0 65 25 10 B
(R = 20%) BF1 360.0 1,350 225 90.0 100 0 0 BF2 360.0 1,350 225 90.0 65 25 10 C
(R = 30%) BF1 315.0 1,350 225 135.0 100 0 0 BF2 315.0 1,350 225 135.0 65 25 10

(2) Experimental results

As a result of evaluating the physical properties of mortar according to the formulation of [Table 8], it was confirmed as shown in [Table 9].

Mortar Property Evaluation Results division Mortar Property Evaluation Results Flow
(Mm) Flexural strength (N / ㎡) Compressive strength (N / ㎡) 1 day 3 days 7 days 28 days 91 days 1 day 3 days 7 days 28 days 91 days Room temperature

(20 ℃) Plain 198 3.4 5.4 6.2 7.8 7.8 13.6 26.7 41.5 47.5 57.8 ABF1 198 3.3 5.2 6.4 8.1 8.1 12.0 25.9 44.5 52.4 61.2 ABF2 203 3.8 6.3 6.7 8.3 8.2 14.2 31.3 45.6 52.3 60.3 BBF1 192 2.8 5.2 6.4 8.3 8.7 10.1 25.2 34.9 46.9 60.9 BBF2 200 4.2 6.6 7.3 9.2 9.1 14.2 32.0 46.8 51.8 65.6 CBF1 207 2.6 5.0 6.2 8.0 8.4 8.7 23.5 32.5 46.1 59.8 CBF2 203 3.8 6.4 7.2 9.1 9.2 12.9 30.4 43.2 50.9 62.6 Low temperature
(10 ℃) Plain ― ― 4.8 5.8 ― ― ― 18.6 32.6 ― ― ABF1 ― ― 4.1 5.6 ― ― ― 16.4 28.7 ― ― ABF2 ― ― 4.8 5.7 ― ― ― 19.3 31.1 ― ― BBF1 ― ― 3.8 5.3 ― ― ― 14.8 26.3 ― ― BBF2 ― ― 4.9 5.6 ― ― ― 19.5 30.9 ― ― CBF1 ― ― 3.3 5.0 ― ― ― 13.0 23.6 ― ― CBF2 ― ― 4.2 5.6 ― ― ― 17.7 29.9 ― ―

On the other hand, the physical properties of the mortar as shown in Table 9 summarized as shown in Figs.

4 shows the flow values, which in some cases are confirmed to have sufficient fluidity.

5 and 6 show the mortar bending strength and compressive strength of each age at room temperature, ABF2, BBF2, BBF2, which substituted the admixture composition according to the present invention as compared to ABF1, BBF1, CBF1 substituted with plain or blast furnace slag fine powder as a whole CBF2 was found to be remarkably superior in the characteristics of flexural strength and compressive strength.

7 and 8 show the 3 and 7 day mortar bending strength and compressive strength at room temperature and low temperature, the case of replacing the admixture composition according to the present invention was equivalent to that of plain, but stronger than when the blast furnace slag fine powder alone Expression characteristics were found to be good. In particular, the strength expression in the low temperature environment is relatively large compared to the case of using the blast furnace slag powder alone, it was confirmed that the early strength improvement effect is excellent in the low temperature environment.

In conclusion, the strength expression characteristics of the mortar's flexural and compressive strengths for deriving the desired amount of admixture composed of blast furnace slag powder, limestone powder, and gypsum were investigated. Flexural strength and compressive strength at were higher than that of plain. Thus, the present invention proposes to replace the admixture composition consisting of blast furnace slag fine powder, limestone high fine powder, gypsum 10 to 35% by weight with respect to the total binder with reference to these results.

Experimental Example 3 Examination of Concrete Application Characteristics of Admixture Composition

(1) Experimental method

An experimental plan was established to confirm whether the admixture composition according to the present invention can be preferably applied to concrete. That is, as shown in Table 10 below, PC (Plain Concrete) using only ordinary ordinary Portland cement, BC (Blast Furnace Slag Concrete) substituted with blast furnace slag fine powder 20% alone, admixtures, and admixtures [Experimental Example 1 Experimental plan was established for MC (Mix Concrete) substituted with 20% of admixture composition SBF3 of optimum composition.

Concrete mix division W / B
(%) G _max
(Mm) S / a
(%) W Unit weight (kg / ㎥) Binder S G AE
Water reducing agent C Slag Admixture P-C 51.5 20 46.5 175 340 0 0 809 967 1.7 B-C 51.5 20 46.5 175 272 68 0 809 967 1.7 M-C 51.5 20 46.5 175 272 0 68 809 967 1.7 Cement: Class 1 Common Portland Cement
Water: Tap water specified in KS F 4009
Fine Aggregate: Maritime (assembly 2.23)
Coarse aggregate: Crushed aggregate (assembly 6.83)
AE water reducing agent: Naphthalene-based high performance AE water reducing agent (standard type)

On the other hand, concrete mixing is mixed with fine aggregate, cement (blast furnace slag fine powder, admixture) and coarse aggregate for 30 seconds using a forced fan mixer in a laboratory at 20 ± 2 ℃, and then dilute AE water reducing agent. The mixture was added for 90 seconds to complete the mixing for a total of 120 seconds. The fabrication of test specimens was carried out in accordance with the Korean Industrial Standard (KS) for each test item. Specific test methods for checking the properties of the concrete properties are shown in Table 11 below.

Concrete property test method Concrete property test method slump  KS F 2402 Air volume  KS F 2421 (using Washington type air flow meter) Compressive strength  KS F 2405 Chloride Penetration Resistance (1) Applying potential difference to specimen-> forced passage of chlorine-ion concrete-> concrete penetration resistance evaluation by passing charge
(2) Penetration resistance test finished test splits 2> KS M ISO 6353-2 R 28
Nitric Acid 0.1N Aqueous Solution Spray-> Determination of Chlorine Ion Penetration Depth

(2) Experimental results

As a result of evaluating the physical properties of the concrete according to the formulation of [Table 10] according to the method of [Table 11], it was confirmed as in the following [Table 12] and [Table 13].

Properties Evaluation of Uncured Concrete division Slump (cm) Air volume (%) Immediately after mixing 40 minutes later Immediately after mixing 40 minutes later P-C 18.5 15.5 6.2 3.7 B-C 21.5 16.0 4.8 3.8 M-C 17.0 15.5 4.1 3.6

Properties Evaluation of Hard Concrete division Compressive strength (N / ㎡) Chloride Penetration Resistance Room temperature (20 ℃) Low temperature
(10 ℃) Passing charge
(× 10 ³ Columbs) Penetration depth
(Mm) 1 day 3 days 7 days 28 days 56 days 3 days P-C 4.7 19.9 24.4 30.9 32.0 14.7 5.124 31.5 B-C 3.0 16.2 21.4 31.9 34.8 10.3 3.862 21.7 M-C 4.4 19.0 27.3 37.6 37.1 13.4 2.983 14.9

On the other hand, the physical properties of the concrete as shown in Table 12 and Table 13 are summarized as shown in Figures 9 to 13.

Figure 9 shows the slump of the concrete and the change over time, as shown, the concrete slump immediately after mixing was measured to have the highest B-C. Although the concrete MC using the admixture composition according to the present invention shows a reduced characteristic compared to the PC, the tolerance of ± 2.5cm in the slump of more than 8cm prescribed in KS F 4009: 2004 (Ready Mixed Concrete) (Within ± 13.8% of the target slump), it does not matter in application.

10 shows the air content and change over time of the concrete, as shown, the concrete air amount immediately after mixing was measured to have the highest P-C. Although the air amount of M-C using the admixture composition according to the present invention was shown to be reduced compared to P-C, it is not a problem in application because it was measured to satisfy the target air amount of 4.5 ± 1.5%.

Figure 11 shows the compressive strength characteristics of concrete by age, MC was measured to express the same level or more strength than the PC in the early age and higher than the PC in the medium and long-term age, MC is the early age and It can be evaluated as being good for securing the compressive strength in the medium to long term age. In addition, Figure 12 shows the characteristics of the compressive strength according to the low temperature (10 ℃) curing of the concrete, the compressive strength of the low-temperature curing concrete is -26.1 ~ -36.2% compared to the compressive strength of the room temperature curing concrete of the same overall Although it is measured to be low, MC is similar to PC, but it is confirmed to be superior to BC, and it is excellent in early strength improvement effect in low temperature environment, so the utilization of MC can be evaluated as a very good level in terms of strength.

Figure 13 shows the amount of penetration charge and chlorine ion penetration depth according to the chlorine ion penetration resistance, as shown in the M-C it is confirmed that the chloride penetration resistance performance is significantly improved compared to P-C and B-C.

After all, the admixture composed of blast furnace slag powder, limestone high powder, and gypsum can be suitably applied to concrete as one of the binders.

1 to 3 show mortar property evaluation results (slump, flexural strength, and compressive strength) for each composition of the admixture composition.

4 to 8 show mortar physical properties evaluation results (slump, flexural strength, compressive strength) for each usage amount of the admixture composition.

9 to 13 show concrete property evaluation results (slump, air amount, compressive strength, chlorine ion passage charge amount, chloride penetration depth) of the admixture composition.

Claims (3)

Blast furnace slag fine powder 60-80% by weight; Limestone high fine powder 15-30% by weight; And, Gypsum 5-10% by weight; The fine limestone powder is characterized in that calcium carbonate (CaCO ₃ ) occupies 75 to 90% by weight, while the powder is 6,000 to 12,000 cm 2 / g, the average particle diameter is 4 to 6 ㎛ and the density is 2.6 to 7 g / cm 3 Premix admixture composition for cement replacement by improving the physical properties of the blast furnace slag fine powder. In claim 1, The limestone high fine powder, Premix admixture composition for cement replacement by improving the physical properties of the blast furnace slag fine powder, characterized in that the dust collected from the grinding and conveying process of the raw material in the cement manufacturing process with a bag filter. The binder composition for concrete, characterized in that the composition by replacing 10 to 35% by weight of the premix admixture composition for cement replacement of claim 1 or 2.

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