High-strength concrete
By using electric furnace slag aggregates and a ternary cement composition, the concrete maintains high compressive strength and achieves a significantly enhanced Young's modulus, addressing the limitations of conventional methods while optimizing workability and cost.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TAISEI CORP
- Filing Date
- 2022-11-04
- Publication Date
- 2026-05-13
AI Technical Summary
Existing methods to increase the Young's modulus of concrete for buildings with large aspect ratios, such as using coarse aggregates with high Young's modulus, result in a decrease in compressive strength, and adjusting the water-cement ratio to maintain strength leads to increased costs and reduced fluidity.
Incorporating electric furnace slag fine and coarse aggregates within specific volume ranges and a ternary cement composition, including ordinary Portland cement, silica fume, and slag lime-based admixture, to achieve high compressive strength without significantly reducing Young's modulus.
The concrete maintains high compressive strength and achieves a Young's modulus that is 20% larger than conventional methods, with improved fluidity and workability, and reduces costs by optimizing the water-cement ratio.
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Abstract
Description
[Technical Field]
[0001] This invention provides a compressive strength of 80 N / mm² at 28 days of age. 2 The above concerns high-strength concrete. [Background technology]
[0002] With the increasing number of skyscrapers, the proportion of buildings with larger aspect ratios is increasing, and this trend is expected to continue. Buildings with large aspect ratios tend to experience greater bending deformation due to horizontal loads such as wind and earthquakes. Therefore, measures such as increasing the rigidity of the column axes are necessary to suppress bending deformation (horizontal displacement associated with bending deformation). Methods to increase the rigidity of the column axis include (1) increasing the amount of reinforcement, (2) increasing the thickness of the concrete-filled steel tube structure (CFT structure), (3) increasing the strength of the concrete, and (4) increasing the Young's modulus of the concrete. Method (1) involves problems such as increased reinforcement work and ensuring proper concrete filling, while method (2) leads to increased costs. Methods (3) and (4) can be achieved by adjusting the concrete mix, but since the rate of increase in column axial stiffness due to the increase in Young's modulus is greater than the rate of increase in column axial stiffness due to the increase in concrete strength, method (4) is more effective than method (3). Regarding the Young's modulus of concrete in (4), various technologies have been reported, as follows: For example, Non-Patent Document 1 shows that concrete containing more coarse aggregate than fine aggregate is more effective in increasing the Young's modulus. Furthermore, Non-Patent Document 2 shows that the type of coarse aggregate has a significant effect on the Young's modulus of concrete, while, unlike coarse aggregate, the type of fine aggregate does not have much effect on the Young's modulus of mortar. Furthermore, Non-Patent Document 3 shows that in ultra-high-strength concrete, the concrete strength tends to decrease as the Young's modulus of the coarse aggregate increases. [Prior art documents]
Non-Patent Literature
[0003]
Non-Patent Literature 1
Non-Patent Literature 2
Non-Patent Literature 3
Summary of the Invention
Problems to be Solved by the Invention
[0004] According to the descriptions in Non-Patent Literatures 1 and 2, it can be seen that fine aggregate does not significantly affect the Young's modulus of concrete, while using coarse aggregate with a high Young's modulus can obtain concrete with a high Young's modulus. However, as described in Non-Patent Literature 3, it has been known that in ultra-high-strength concrete, using coarse aggregate with a high Young's modulus will result in a decrease in the strength of the concrete. Therefore, in order to increase the Young's modulus of the concrete, it was necessary to use coarse aggregate with a large Young's modulus while accepting that the compressive strength would decrease. Also, when the decrease in the compressive strength of the concrete cannot be tolerated, the water-cement ratio may be reduced, but this not only reduces the fluidity and makes the placing work time-consuming but also increases the cost. Therefore, the inventors considered creating high-strength concrete that achieves both high compressive strength and high Young's modulus, which could not be realized by the conventional techniques including the above-mentioned non-patent literatures without changing the water-cement ratio.
[0005] Therefore, an object of the present invention is to provide high-strength concrete having a large Young's modulus without a significant decrease in compressive strength.
Means for Solving the Problems
[0006] The high-strength concrete according to the present invention for solving the above problems is high-strength concrete having a compressive strength of 80 N / mm or more at 28 days of age, 2 including 500 to 1000 kg / m of binder B containing cement, 3 and 150 to 180 kg / m of water W added so that the weight ratio W / B to the binder is 15 to 30%, and contains 3 at least one of electric furnace slag fine aggregate EFS having an absolute volume of 130 to 430 L / m and electric furnace slag coarse aggregate EFG having an absolute volume of 165 to 330 L / m. 3 3 3 3 Further, the electric furnace slag fine aggregate of the high-strength concrete according to the present invention preferably has an absolute dry density of 3.6 g / cm or more and a water absorption rate of 2.0% or less. 3 3 Further, the binder of the high-strength concrete according to the present invention is a ternary cement. When the total weight of the binder is 100, the weight of ordinary Portland cement is preferably 68 to 72, the weight of silica fume is 8 to 12, and the weight of slag lime-based admixture is 18 to 22. Since the high-strength concrete according to the present invention contains at least one of electric furnace slag fine aggregate and electric furnace slag coarse aggregate so that the absolute volume is within a predetermined range, the compressive strength does not significantly decrease and the Young's modulus becomes a large value.
Advantages of the Invention
[0007] The high-strength concrete according to the present invention has a large Young's modulus without a significant decrease in compressive strength.
Brief Description of the Drawings
[0009] The following describes an embodiment of the high-strength concrete according to the present invention (high-strength concrete according to this embodiment). [High-strength concrete] The high-strength concrete according to this embodiment contains a binder including cement and water, and contains at least one of an electric furnace oxidized slag fine aggregate and an electric furnace oxidized slag coarse aggregate. And, in the high-strength concrete according to this embodiment, the content of the binder, the weight ratio and content of water, the content of the electric furnace oxidized slag fine aggregate, and the content of the electric furnace oxidized slag coarse aggregate are each within a predetermined range. Hereinafter, each constituent element will be described in detail.
[0010] (Electric furnace oxidized slag fine aggregate) The electric furnace slag is an electric furnace slag generated when melting and refining iron scrap, and includes oxidized slag generated by oxidative refining and reduced slag generated by reduction refining. And, the electric furnace oxidized slag fine aggregate is a material using oxidized slag, and specifically, it is a fine aggregate that satisfies the requirements described in "Slag Aggregate for Concrete - Part 4: Electric Furnace Oxidized Slag Aggregate" of JIS A 5011-4:2018. The inventors have found that the electric furnace oxidized slag fine aggregate can increase the Young's modulus without significantly reducing the compressive strength of concrete. (Absolute volume of electric furnace oxidized slag fine aggregate) The volume (absolute volume) of the electric furnace oxidized slag fine aggregate per 1 m 3 of high-strength concrete. If it is less than 130 L / m 3 , there is a possibility that the effect of increasing the Young's modulus cannot be obtained sufficiently. On the other hand, if the absolute volume of the electric furnace oxidized slag fine aggregate exceeds 430 L / m 3 , there is a possibility that the fluidity will decrease. Therefore, the absolute volume of the electric furnace oxidized slag fine aggregate is 130 to 430 L / m 3 , preferably 130 to 410 L / m 3 . (Properties of electric furnace oxidized slag fine aggregate) The properties of the electric furnace oxidized slag fine aggregate are not particularly limited, but the absolute dry density is 3.6 g / cm 3 or more (preferably 3.7 g / cm 3(As described above) The water absorption rate is 2.0% or less (preferably 0.8% or less), and the coarseness ratio is 2.00 to 3.50. Furthermore, the oven-dry density and water absorption rate can be measured according to the method described in JIS A 1109:2020, and the coarseness ratio can be measured according to the method described in JIS A1102:2014.
[0011] (Electric furnace oxidized slag coarse aggregate) Electric furnace slag coarse aggregate refers to coarse aggregate made from electric furnace slag, which is produced when iron scrap is melted and refined. Among electric furnace slag coarse aggregates, electric furnace oxidized slag coarse aggregate is a coarse aggregate that meets the requirements described in the JIS standard, similar to the electric furnace oxidized slag fine aggregate mentioned above. The inventors have found that, similar to fine aggregates made from electric furnace oxidized slag, coarse aggregates made from electric furnace oxidized slag can increase the Young's modulus of concrete without significantly reducing its compressive strength. (Absolute volume of coarse aggregate in electric furnace oxidized slag) High-strength concrete 1m 3 The volume (absolute volume) of coarse aggregate in an electric furnace oxidized slag is 165 L / m³. 3 If the value is less than 330 L / m³, the effect of increasing the Young's modulus may not be fully obtained. On the other hand, if the absolute volume of the coarse aggregate of the electric furnace oxidized slag is 330 L / m³ 3 If it exceeds this level, a decrease in liquidity may occur. Therefore, when electric furnace oxidized slag coarse aggregate is included, the absolute volume of the electric furnace oxidized slag coarse aggregate is 165 to 330 L / m³. 3 That is the case. (Characteristics of coarse aggregate made from electric furnace oxidized slag) The properties of coarse aggregate from electric furnace oxidized slag are not particularly limited, but the oven-dry density is 3.5 g / cm³. 3 (preferably 3.65 g / cm³) 3 (As described above) The water absorption rate is 1.5% or less (preferably 0.7% or less), and the coarseness ratio is 5.00 to 7.50. In the high-strength concrete according to this embodiment, if either electric furnace oxidized slag fine aggregate or electric furnace oxidized slag coarse aggregate is included, it is sufficient to include them in a predetermined absolute volume. If both electric furnace oxidized slag fine aggregate and electric furnace oxidized slag coarse aggregate are included, it is preferable to include them in a predetermined absolute volume.
[0012] (Binding material) The binder is composed of cement. The binder may be a premixed product that has been mixed in a predetermined proportion beforehand, or it may be mixed during the concrete manufacturing process. And, high-strength concrete 1m 3 The weight (absolute weight) of the binder per unit area is 500-1000 kg / m 3 That is the case. Furthermore, the binder is preferably a three-component cement, consisting of ordinary Portland cement, silica fume, and a slag-gypsum-based admixture. When the total weight of the binder is set to 100, the weight of ordinary Portland cement is preferably 68 to 72, the weight of silica fume is preferably 8 to 12, and the weight of slag gypsum-based admixture is preferably 18 to 22. Ordinary Portland cement refers to materials conforming to the specifications described in JIS R 5210:2009. Silica fume refers to materials defined in JIS A 6207:2016. Slag gypsum admixtures refer to materials conforming to the standards described in Annex 3 of JASS 5 M-701:2018.
[0013] (water) If the weight ratio of water to the binder is less than 15%, the fluidity may deteriorate. Furthermore, if the weight ratio of water to the binder exceeds 30%, the desired compressive strength may not be achieved. Therefore, water is added in such a weight ratio to the binder that it is 15-30%. Also, high-strength concrete 1m 3 The weight of water per unit volume is 150 kg / m³. 3If the water content is below a certain level, the fluidity of the fresh concrete deteriorates, reducing workability. Also, the water content must be 180 kg / m³. 3 If this amount is exceeded, the amount of binder will increase, which may reduce durability. Therefore, the unit water volume is 150-180 kg / m³. 3 That is the case.
[0014] (Compressive strength) The high-strength concrete according to this embodiment has a compressive strength of 80 N / mm² at 28 days of age. 2 That's all. Furthermore, the compressive strength at 28 days of age refers specifically to the value obtained by the test method specified in JIS A1108:2018, "Test Method for Compressive Strength of Concrete," when a cylindrical specimen with a diameter of 10 cm and a height of 20 cm is subjected to standard curing (curing in water at 20°C) at 28 days of age.
[0015] (Young's modulus) In the high-strength concrete according to this embodiment, the Young's modulus (static elastic modulus) is Ec = 3.35 × K × (γ / 2.4) as shown in "Architectural Institute of Japan: Standard Specifications for Building Construction and Commentary JASS5 Reinforced Concrete Construction". 2 ×(Fc / 60) 1 / 3 This value is more than 20% larger than the calculated value (K=1.0, γ=2.4) obtained by "[this method]". The Young's modulus (static modulus) is an index that indicates the amount of deformation of a material when a static force is applied, and is a value obtained by the test method specified in JIS A1149:2017 "Test Method for Static Modulus of Concrete".
[0016] (others) In addition to the binder, electric furnace oxidized slag fine aggregate, electric furnace oxidized slag coarse aggregate, and water, the high-strength concrete according to this embodiment may also contain the following: In addition to electric furnace oxidized slag fine aggregate, the material may also contain one or more types of fine aggregate selected from mountain sand, river sand, sea sand, crushed sand, silica sand, lime sand, etc. In addition to electric furnace oxidized slag coarse aggregate, natural gravel or crushed stone coarse aggregate may also be included as coarse aggregate. Furthermore, the high-strength concrete according to this embodiment may contain conventionally known admixtures such as segregation reducing agents, water-reducing agents, high-performance water-reducing agents, defoaming agents, setting retarders, setting accelerators, air-entraining agents, air-entraining water-reducing agents, and high-performance air-entraining water-reducing agents, as well as organic fibers, steel fibers, and other substances commonly used in concrete. [Examples]
[0017] [Example 1] [Test details for Example 1] Table 2 shows the composition of the mortar and concrete materials used in Example 1. The symbols in Table 2 are as shown in Table 1. First, 10 liters each of the mortars (No. 1-2) shown in Table 2 were pre-mixed using a Hobart mixer. After the mortars (No. 1-2) were mixed, coarse aggregate was added as needed, and concrete (No. 3-7) was mixed by hand. Immediately after mixing, three test specimens (cylindrical cylinders with a diameter of 10 cm and a height of 20 cm) were taken for each type of concrete. The collected specimens were placed in a sealed state in a constant temperature and humidity chamber at 20°C. After one day, they were demolded, and standard curing (curing in water at 20°C) was started. Compressive strength tests and static elastic modulus tests were then performed on each of the three specimens at 28 days of age in an environment of approximately 20°C, and the average values were calculated to determine the compressive strength and Young's modulus (static elastic modulus). The compressive strength test was conducted in accordance with JIS A1108:2018, "Test Method for Compressive Strength of Concrete". The static elastic modulus test was conducted in accordance with JIS A1149:2017, "Test Method for Static Elastic Modulus of Concrete". Furthermore, the EFS, which is the fine aggregate of electric furnace oxidized slag used in Example 1, was manufactured by crushing and then classifying slowly cooled slag (electric furnace oxidized slag). Furthermore, the oven-dry density and water absorption rate shown in Table 1 were measured according to the method described in JIS A1109:2020, the coarseness ratio was measured according to the method described in JIS A1102:2014, and the volume ratio was measured according to the method described in JIS A1104:2019.
[0018] [Table 1]
[0019] [Table 2]
[0020] [Table 3]
[0021] (Review of results regarding mortar) Figure 1 shows the results for the compressive strength and Young's modulus of mortars No. 1 and 2. From the results in Figure 1 and Table 3, it was confirmed that the compressive strength of the mortar increased with the use of EFS (No.2[M-S10]). Furthermore, it was confirmed that the Young's modulus of the mortar also increased by approximately 13% with the use of EFS (No.2 [M-S10]).
[0022] (Review of results regarding concrete) Figure 2 shows the results of the compressive strength of concrete samples No. 3 to 7. From the results in Figure 2 and Table 3, it was confirmed that the compressive strength of concrete increases with the use of EFG, regardless of the type of fine aggregate (No. 4 [C-G10], No. 6 [C-S10-G5], No. 7 [C-S10-G10]). Furthermore, comparing No. 3[C] and No. 5[C-S10] in Figure 2 and Table 3, it was confirmed that the compressive strength of the concrete did not change with the use of EFS. In other words, even with the use of EFS, the compressive strength of the concrete did not decrease, and sufficient compressive strength (100 N / mm²) was maintained. 2 We confirmed that the above conditions were met. Figure 3 shows the results for the Young's modulus of concrete samples No. 3 to 7. Comparing Figure 3 and Table 3, No. 3[C] and No. 5[C-S10], it was confirmed that the Young's modulus of concrete increases with the use of EFS. Therefore, these results confirm that the use of electric furnace oxidized slag fine aggregate (EFS) allows for the maintenance of high compressive strength without significantly reducing the compressive strength of concrete, while also increasing the Young's modulus.
[0023] Figure 4 shows the relationship between the compressive strength (Fc) and Young's modulus (Ec) of concrete samples No. 3 to 7. The results in Figure 4 show that, when comparing concretes with similar compressive strengths, the Young's modulus of concrete using EFS (legend: square) tends to be approximately 10% larger than that of concrete without EFS (legend: circle). Note that the solid line in Figure 4 represents "Ec = 3.35 × K × (γ / 2.4) 2 ×(Fc / 60) 1 / 3 This formula is obtained by substituting K=1.2 and γ=2.4 into the equation shown above, which is presented in "Architectural Institute of Japan: Standard Specifications for Building Construction and Commentary JASS5 Reinforced Concrete Construction".
[0024] Figure 5 shows the relationship between the Fc / Fm values of concrete No. 3 to 7 and the apparent Young's modulus of the coarse aggregate. In detail, based on the Hashin-Hansen formula, the "apparent Young's modulus of coarse aggregate" for samples No. 3-7 was calculated from the measured Young's modulus values of mortar and concrete and the volume of coarse aggregate. Then, Fc / Fm was calculated from the measured Young's modulus values (Fc) of concrete for samples No. 3-7 and the corresponding measured Young's modulus values (Fm) of mortar, and plotted in Figure 5. The Hashin-Hansen formula is as follows: E H·H =[{(1-Va)Em+(1+Va)Ea} / {(1+Va)Em+(1-Va)Ea}]Em E H·H : Estimated value of Young's modulus of concrete (×10 4 N / mm 2 ) Em: Young's modulus of mortar (×10 4 N / mm 2 ) Ea: Young's modulus of coarse aggregate (×10 4 N / mm 2 ) Va: Absolute volume of coarse aggregate per unit (m³) 3 / m 3 ) In Figure 5, "G used" refers to plots for No. 3 and 5, "G and EFG used" refers to plots for No. 6, and "EFG used" refers to plots for No. 4 and 7 in Table 3. As shown in Figure 5, even when using the same coarse aggregate, variations in the apparent Young's modulus were observed. However, the Fc / Fm value tended to be higher and the concrete strength higher when using EFG (electric furnace oxidized slag coarse aggregate) compared to when using G (limestone). Furthermore, a positive correlation was observed between the apparent Young's modulus and the Fc / Fm value regardless of the type of coarse aggregate. However, this result differs from previous findings (such as Non-Patent Document 3) that, when comparing mortar strengths at the same level, a smaller Young's modulus of the coarse aggregate leads to higher concrete strength.
[0025] [Example 2] [Test details for Example 2] Table 5 shows the composition of the concrete material used in Example 2. The symbols in Table 5 are as shown in Table 4. First, 10 liters each of mortar (materials other than the coarse aggregate shown in Table 5) were pre-mixed using a Hobart mixer. After the mortar was mixed, coarse aggregate was added as needed, and concrete (No. 8-20) was mixed by hand. Immediately after mixing, three test specimens (cylindrical cylinders with a diameter of 10 cm and a height of 20 cm) were taken for each test. The collected specimens were left undisturbed in a sealed state in a constant temperature and humidity chamber at 20°C. After one day, they were demolded, and standard curing (curing in water at 20°C) was started. Compressive strength tests and static elastic modulus tests were then performed on each of the three specimens at 28 days of age in an environment of approximately 20°C, and the average values were calculated to determine the compressive strength and Young's modulus (static elastic modulus). The compressive strength test and static modulus test were performed in accordance with JIS standards, as in Example 1. Furthermore, the EFS (fine aggregate) and EFG (coarse aggregate) of electric furnace oxidized slag used in Example 2 were manufactured by crushing and classifying slowly cooled slag (electric furnace oxidized slag). Furthermore, the oven-dry density, water absorption rate, and coarseness ratio shown in Table 4 were measured using the method described in JIS, as in Example 1.
[0026] [Table 4]
[0027] [Table 5]
[0028] [Table 6]
[0029] (Review of the results of Example 2) Figure 6 shows the results for compressive strength and Young's modulus of concrete samples No. 8-11 (W / B ratio of 30%). Figure 7 shows the results for compressive strength and Young's modulus of concrete samples No. 12-15 (W / B ratio of 20%). Figure 8 shows the results for compressive strength and Young's modulus of concrete samples No. 16-20 (W / B ratio of 15%). The results shown in Figures 6-8 confirm that, regardless of the W / B ratio and aggregate content, the Young's modulus was higher when EFS was used compared to when NS was used. Furthermore, the increase in Young's modulus due to the use of EFS was particularly pronounced when the W / B ratio was high or when the binder B was of low strength, with an increase of approximately 30% observed at a W / B ratio of 30%. Regarding compressive strength, the samples using EFS were equivalent to or better than those using NS, and no adverse effects due to the use of EFS were observed. In No. 20 [C15-E-E310], which used EFG as coarse aggregate, not only was the Young's modulus further increased, but a 10-20% increase in compressive strength was also observed. This is thought to be due to the fact that electric furnace oxidized slag coarse aggregate has a more uneven surface than general coarse aggregate, resulting in better adhesion with mortar.
[0030] Figure 9 shows the relationship between the compressive strength and Young's modulus of concrete samples No. 8 to 20. Furthermore, the solid line in Figure 9 represents the formula "Ec = 3.35 × K × (γ / 2.4)" as shown in the aforementioned "Architectural Institute of Japan: Standard Specifications for Building Construction and Commentary JASS5 Reinforced Concrete Construction". 2 ×(Fc / 60) 1 / 3 The equation is obtained by substituting K=1.0 and γ=2.4, and the dotted line in Figure 9 is obtained by substituting K=1.2 and γ=2.4 into the same equation. The results in Figure 9 confirm that using EFS yields a Young's modulus 1.2 times the calculated value shown in "Architectural Institute of Japan: Standard Specifications and Commentary for Building Construction JASS5 Reinforced Concrete Construction". Furthermore, it was confirmed that a Young's modulus 1.2 times the calculated value was obtained regardless of whether limestone coarse aggregate (LG) or electric furnace oxidized slag coarse aggregate (EFG) was used.
[0031] Above, W / B30~15%, coarse aggregate amount 250~370L / m 3 , fine aggregate amount 126~413L / m 3 Based on experimental data, we were able to demonstrate that the use of electric furnace oxidized slag fine aggregate increases the Young's modulus within the specified range (achieving a Young's modulus 1.2 times the calculated value shown in "Architectural Institute of Japan: Standard Specifications for Building Construction and Commentary JASS5 Reinforced Concrete Construction"). The reason for the increase in the Young's modulus of concrete due to the use of electric furnace oxidized slag fine aggregate is considered to be the high Young's modulus of the electric furnace oxidized slag fine aggregate, as shown in the Hashin-Hansen equation. Therefore, it is assumed that a similar Young's modulus increase effect can be obtained even when the W / B ratio is greater than that shown in the example, or when the binder B is in the low-strength range. Furthermore, the effects observed in the examples are not limited to the type of materials used; similar effects can be obtained with formulations that include fibers, for example, which are mixed in to suppress spalling in ultra-high-strength concrete.
[0032] (Effects and Benefits) The high-strength concrete of this embodiment has a compressive strength of 80 N / mm² at 28 days of age. 2 The above high-strength concrete contains cement with a density of 500-1000 kg / m³ 3 The binder and 150-180 kg / m³ added in a weight ratio of 15-30% to the binder. 3 It contains water and has an absolute volume of 130-430 L / m³. 3 The electric furnace oxidized slag fine aggregate has an absolute volume of 165-330 L / m³. 3 This is achieved by containing at least one of the following: electric furnace oxidized slag coarse aggregate and the electric furnace oxidized slag fine aggregate having an oven-dry density of 3.6 g / cm³. 3 Preferably, the water absorption rate is 2.0% or less. Furthermore, the binder is a three-component cement, and when the total weight of the binder is 100, it is preferable that the weight of ordinary Portland cement is 68 to 72, the weight of silica fume is 8 to 12, and the weight of slag gypsum-based admixture is 18 to 22. According to the high-strength concrete of this embodiment, since it contains at least one of electric furnace oxidized slag fine aggregate and electric furnace oxidized slag coarse aggregate such that their absolute volumes are within a predetermined range, the compressive strength does not decrease significantly, and the Young's modulus is high.
Claims
1. Compressive strength at 28 days of age: 80 N / mm ２ The above high-strength concrete, 500-1000 kg / m³ including cement ３ The binder and The additive is 150-180 kg / m³, added in a weight ratio of 15-30% to the aforementioned binder. ３ It contains water, Absolute volume is 130-430 L / m³ ３ The electric furnace oxidized slag fine aggregate has an absolute volume of 165 to 330 L / m³. ３ It contains at least one of the following: electric furnace oxidized slag coarse aggregate, The aforementioned electric furnace oxidized slag fine aggregate is a high-strength concrete characterized by having an oven-dry density of 3.6 g / cm³ or more and a water absorption rate of 2.0% or less.
2. Compressive strength at 28 days of age: 80 N / mm ２ The above high-strength concrete, 500-1000 kg / m³ including cement ３ The binder and The additive is 150-180 kg / m³, added in a weight ratio of 15-30% to the aforementioned binder. ３ It contains water, The electric furnace oxidized slag fine aggregate with an absolute volume of 130 to 430 L / m ３ and the electric furnace oxidized slag coarse aggregate with an absolute volume of 165 to 330 L / m ３ contains at least one of them The binder is a three-component cement, and when the total weight of the binder is 100, the weight of ordinary Portland cement is 68 to 72, the weight of silica fume is 8 to 12, and the weight of slag gypsum-based admixture is 18 to 22, making it a high-strength concrete.