Concrete and method for producing same

Abstract

The present invention provides a kind of concrete and its preparation method.The concrete includes: 11wt% to 20wt% of sodium (Na), 3wt% to 6wt% of magnesium (Mg), 7wt% to 11wt% of aluminum (Al), 15wt% to 22wt% of silicon (Si), 0.4wt% to 0.7wt% of potassium (K), and 49wt% to 53wt% of calcium (Ca), based on the total weight of sodium, magnesium, aluminum, silicon, potassium and calcium in the concrete, and the concrete includes calcium alumino-silicate compound.

Description

Technical Field

[0001] This invention relates to a type of concrete and a method for preparing the concrete. Background Technology

[0002] Concrete is a material used in various construction projects, such as public infrastructure, buildings, and home maintenance. The main components of concrete are cement and water. Traditional concrete has very high carbon emissions, with 90% of these emissions coming from cement production. However, cement production requires the use of fossil fuels and rotary kiln calcination processes. Statistics show that cement production accounts for approximately 8% of global carbon dioxide emissions. Faced with increasingly stringent emission standards and pressure to reduce carbon emissions, there is a need to develop low-carbon cement technologies. Furthermore, concrete manufacturing requires large quantities of natural sand and gravel, a finite natural resource; therefore, replacing or reducing the use of natural sand and gravel is an urgent issue that the industry must address.

[0003] On the other hand, steel mills face the problem of disposing of furnace slag, such as reduction slag, oxide slag, and sand. Currently, most steelmaking furnace slag is directly transported to self-planned slag dumps for dumping and landfill, causing serious environmental pollution. In addition, industrial waste alkali generated from the pretreatment of dust collection ash requires costly treatment methods to avoid pollution.

[0004] Therefore, there is an urgent need to provide an advanced concrete and its preparation method that reduces carbon emissions in the concrete production process and effectively reuses waste, in order to solve the problems faced by conventional technologies. Summary of the Invention

[0005] According to embodiments of the present invention, the present invention provides a concrete. The concrete may contain 11 wt% to 20 wt% sodium (Na), 3 wt% to 6 wt% magnesium (Mg), 7 wt% to 11 wt% aluminum (Al), 15 wt% to 22 wt% silicon (Si), 0.4 wt% to 0.7 wt% potassium (K), and 49 wt% to 53 wt% calcium (Ca), based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium in the concrete, and the concrete contains a calcium aluminum silicate compound.

[0006] According to embodiments of the present invention, the present invention provides a method for preparing concrete, for preparing the concrete described herein. The method for preparing concrete may include the following steps: providing a concrete mixture, wherein the concrete mixture may include a cementitious material and a waste alkali solution; performing a casting process on the concrete mixture to obtain a green body; and performing a curing process on the green body at room temperature to obtain the concrete described herein. The cementitious material comprises 35 to 70 parts by weight of blast furnace slag and 30 to 65 parts by weight of reducing aggregate. The waste alkali solution may contain sodium ions, and the concentration of the sodium ions is 100,000 ppm to 150,000 ppm; and the weight ratio of the waste alkali solution to the cementitious material may be 3:10 to 5:10. Attached Figure Description

[0007] Figure 1 This is a flowchart of the concrete preparation method 10 according to an embodiment of the present invention.

[0008] Figure 2 The image is a scanning electron microscope (SEM) image of the concrete column (1) described in Example 1.

[0009] Figure 3 For comparison, the scanning electron microscope (SEM) images of the concrete column (4) described in Example 1 are shown.

[0010] In the attached figures, the following labels are used:

[0011] 10. Methods for preparing concrete; and

[0012] Steps 12, 14, and 16. Detailed Implementation

[0013] The following provides a detailed description of the concrete and its preparation method according to the present invention. It should be understood that the following description provides many different embodiments or examples for implementing different variations of the invention. The specific components and arrangements described below are merely a simplified description of the invention. Of course, these are only illustrative and not intended to limit the invention. The term "about" as used in this invention refers to a value that includes the stated value and a range of acceptable deviations taken into account by those skilled in the art, considering measurement problems and measurement errors (i.e., limitations of the measurement system). For example, "about" may represent a value within one or more standard deviations of the stated value or within ±5% of the stated value. The quantities given herein are approximate quantities, meaning that the meanings of "about," "approximately," and "substantially" are implied even without specific descriptions of "about," "approximately," or "substantially." In this invention, the expression "a to b" indicates values ​​greater than or equal to a and values ​​less than or equal to b.

[0014] It is understood that although terms such as "first," "second," and "third" may be used herein to describe various components, constituent parts, regions, layers, and / or portions, these components, constituent parts, regions, layers, and / or portions should not be limited by these terms, and these terms are only used to distinguish different components, constituent parts, regions, layers, and / or portions. Therefore, a first component, constituent part, region, layer, and / or portion discussed below may be referred to as a second component, constituent part, region, layer, and / or portion without departing from the teachings of some embodiments of the present invention.

[0015] Unless otherwise defined, all terms used in this invention (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary knowledge in the art to which this invention pertains. It will be further understood that terms defined in common dictionaries shall be interpreted as having the same meaning as their meaning in the relevant art and in the content of this invention, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0016] This invention provides a concrete and a method for preparing the same, for example, concrete prepared using industrial by-products (or waste) and its preparation method. This invention enables the resource-based reuse of industrial by-products (or waste) to obtain environmentally friendly concrete that can cure at room temperature, has high compressive strength, and low toxicity. The concrete preparation method of this invention provides a concrete mixture, wherein the concrete mixture is obtained by mixing a specific cementitious material derived from industrial by-products (or waste) with a waste alkaline solution, wherein the cementitious material contains a specific amount of blast furnace slag and reducing aggregate, and the waste alkaline solution contains sodium ions, and the concentration of the sodium ions is from 100,000 ppm to 150,000 ppm. By using this waste alkaline solution as an alkali activator (replacing expensive chemical alkalis) and mixing it with the cementing material in a specific ratio, the metal oxides such as silicon dioxide (SiO2), aluminum oxide (Al2O3), calcium oxide (CaO), and magnesium oxide (MgO) in the cementing material can undergo alkali activation, recombination, and polymerization reactions at room temperature. This results in an inorganic polymer containing highly dense gel-like calcium aluminum silicate, which helps to fix and encapsulate heavy metals, preventing their release. Consequently, the concrete mixture of this invention has an appropriate curing speed at room temperature, and the resulting concrete exhibits low toxicity, anti-expansion properties, and high compressive strength. In summary, the concrete and its preparation method of this invention have the following advantages: good workability, lower raw material costs, avoidance of the use of natural sand and gravel, solution to waste disposal problems, low carbon emissions, and achievement of resource reuse. It can replace traditional concrete (e.g., concrete mixtures containing Portland Type I cement, natural sand and gravel, and chemical alkalis).

[0017] According to an embodiment of the present invention, the concrete of the present invention may contain about 11 wt% to 20 wt% (such as 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, or 19 wt%) of sodium (Na), 3 wt% to 6 wt% (such as 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, or 5.5 wt%) of magnesium (Mg), 7 wt% to 11 wt% (such as 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, or 10.5 wt%) of aluminum (Al), 15 wt% to 22 wt% (such as 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, or 21 wt%) of silicon (Si), 0.4 wt% to 0.7 wt% (such as 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%, or 0.65 wt%) of potassium (K), and 49 wt% to 53 wt% (such as 49.5 wt%, 50 wt%, 50.5 wt%, 51 wt%, 51.5 wt%, 52 wt%, or 52.5 wt%) of calcium (Ca). The weight percentages of the above elements are based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium elements in the concrete. According to an embodiment of the present invention, the contents of sodium, magnesium, aluminum, silicon, potassium, and calcium elements in the concrete of the present invention can be determined by an X-ray fluorescence spectrometer (XRF).

[0018] According to an embodiment of the present invention, the concrete contains a calcium aluminosilicate compound. According to an embodiment of the present invention, the calcium aluminosilicate compound has a structure shown in Formula (I).

[0019] Ca a Al b (SiO4) c Formula (I)

[0020] , where 0 < a ≤ 3, 0 < b ≤ 2, and 0 < c ≤ 3. For example, the structure of the calcium aluminosilicate compound is Ca3Al2(SiO4)3.

[0021] According to an embodiment of the present invention, the concrete of the present invention is substantially composed of sodium, magnesium, aluminum, silicon, potassium, calcium, oxygen, and sulfur elements. Here, "the concrete is substantially composed of sodium, magnesium, aluminum, silicon, potassium, calcium, oxygen, and sulfur elements" means that the content of elements other than sodium, magnesium, aluminum, silicon, potassium, calcium, oxygen, and sulfur elements in the concrete is less than 5 wt% (such as less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1 wt%), based on the total weight of the concrete.

[0022] According to embodiments of the present invention, the concrete further comprises element X, wherein element X refers to elements other than sodium, magnesium, aluminum, silicon, potassium, calcium, oxygen, and sulfur, and the weight ratio of element X in the concrete to the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium in the concrete can be approximately 0.1:99.9 to 10:90, for example, approximately 0.2:99.8, 0.5:99.5, 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, or 9:91. The content of each element in the concrete of the present invention can be determined using an X-ray fluorescence spectrometer (XRF).

[0023] According to embodiments of the present invention, in the concrete described herein, the weight ratio of sodium to silicon can be approximately 1:2 to 4:3 (e.g., approximately 2:3, 3:4, 4:5, 9:10, 1:1, 10:9, 7:6, or 5:4). According to embodiments of the present invention, when the atomic ratio of sodium to silicon in the concrete described herein is within the above range, the concrete of the present invention has a denser structure, thereby improving the physical properties of the concrete (e.g., compressive strength).

[0024] According to embodiments of the present invention, the sodium, magnesium, aluminum, silicon, potassium, and / or calcium contained in the concrete of the present invention may exist in the form of oxides (e.g., sodium oxide, magnesium oxide, aluminum oxide, silicon oxide, potassium oxide, calcium oxide, calcium silicate, magnesium silicate, aluminum silicate, calcium magnesium silicate, calcium aluminum silicate, and / or calcium aluminum silicate, etc.), therefore the concrete of the present invention is a composite oxide.

[0025] According to an embodiment of the present invention, the characteristic peak value (2θ) of calcium aluminum silicate in the X-ray diffraction spectrum of the concrete described in the present invention is 43.4 degrees to 44.5 degrees.

[0026] According to an embodiment of the present invention, the characteristic peak value (2θ) of the X-ray diffraction pattern of the concrete at 43.4 degrees to 44.5 degrees may have a first integrated intensity (S1), and the characteristic peak value (2θ) of the X-ray diffraction pattern of the concrete at 31.9 degrees to 32.2 degrees may have a second integrated intensity (S2), wherein the ratio of the first integrated intensity to the second integrated intensity (S1 / S2) is 0.03 to 0.15, for example, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, or 0.14. When the ratio (S1 / S2) is too low or is 0, it indicates that the cementitious material used to form the concrete does not tend to gel, resulting in a low content of calcium aluminosilicate in the concrete or no formation of calcium aluminosilicate, and the resulting concrete has a looser structure (lower density and larger average pore size). This results in a decrease in the compressive strength of the concrete, and the loose structure makes it easier for heavy metal elements contained in the concrete column to diffuse out.

[0027] According to an embodiment of the present invention, the density of the concrete can be approximately 2.2 g / cm³. 3 Up to 2.4 g / cm 3 According to an embodiment of the present invention, the concrete described herein, after being cured at room temperature for 28 days, has a compressive strength greater than or equal to 440 kgf / cm². 2 (For example, it could be approximately 440 kgf / cm²) 2 Up to 700 kgf / cm 2 According to an embodiment of the present invention, the compressive strength is assessed by measuring it using a compressive strength measuring instrument (model Zwick Roell Z020, Zwick / Roell GmbH) according to the method specified in ASTM C109.

[0028] According to an embodiment of the present invention, in the Fourier-transform infrared spectroscopy (FTIR) image of the concrete described in the present invention, at 1,000 cm⁻¹... -1 Up to 1,150cm -1 The presence of characteristic peaks within the range indicates that the blast furnace slag reacts with the reducing slag and undergoes changes or recombination of the gel structure to form a Si-OT (T is SiO4 or AlO4) structure.

[0029] According to embodiments of the present invention, the present invention also provides a method for preparing concrete, for preparing the concrete described herein. Please refer to... Figure 1According to an embodiment of the present invention, the concrete preparation method 10 includes providing a concrete mixture (step 12). The concrete mixture is subjected to a casting process to obtain a green body (step 14). The green body is then subjected to a curing process at room temperature to obtain the concrete (step 16).

[0030] According to an embodiment of the present invention, the concrete mixture may comprise a binder and a waste alkali solution. According to an embodiment of the present invention, the binder may be entirely derived from steel mill waste. For example, the binder may comprise 35 to 70 parts by weight (e.g., 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, or 69 parts by weight). ) blast furnace slag, and 30 to 65 parts by weight (e.g., 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, or 64 parts by weight) of reducing slag.

[0031] According to embodiments of the present invention, since the reactivity of the reducing slag is relatively low, when the amount of reducing slag is too high (i.e., the amount of blast furnace ash is too low), the resulting concrete structure is less dense (i.e., the porosity increases), leading to insufficient compressive strength of the concrete. Furthermore, when the amount of reducing slag is too low (i.e., the amount of blast furnace ash is too high), the concrete mixture is prone to having a shorter curing time, affecting the formation of calcium aluminosilicates within the concrete.

[0032] According to embodiments of the present invention, the cementing material may be composed of the blast furnace slag and the reducing slag. According to embodiments of the present invention, the blast furnace slag and / or the reducing slag may be derived from converter slag, oxide slag, coal fly ash, coal bottom ash, aluminum slag, waste catalyst, waste building materials, waste gypsum, sludge, bottom mud, sulfuric acid slag, calcium sulfate, or a combination thereof. According to embodiments of the present invention, the blast furnace slag may contain 0.1 wt% to 0.5 wt% (e.g., 0.2 wt%, 0.3 wt%, or 0.4 wt%) of sodium (Na), 5 wt% to 8 wt% (e.g., 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, or 7.5 wt%) of magnesium (Mg), and 13 wt% to 16 wt% (e.g., 13.5 wt%, 14 wt%, 14.5 wt%, 15 wt%, or 15.5 wt%) of sodium (Na), magnesium (Mg), and reducing slag (Mg). The blast furnace ore contains 24 wt% to 27 wt% (e.g., 24.5 wt%, 25 wt%, 25.5 wt%, 26 wt%, or 26.5 wt%) of aluminum (Al), 0.2 wt% to 0.7 wt% of potassium (K), and 50 wt% to 55 wt% (e.g., 51 wt%, 52 wt%, 53 wt%, or 54 wt%) of calcium (Ca), based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium in the blast furnace ore. According to embodiments of the present invention, the reducing slag may contain 0.2 wt% to 0.6 wt% (e.g., 0.3 wt%, 0.4 wt%, or 0.5 wt%) of sodium (Na), 3 wt% to 6 wt% (e.g., 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, or 5.5 wt%) of magnesium (Mg), 1 wt% to 3 wt% (e.g., 1.5 wt%, 2 wt%, or 2.5 wt%) of aluminum (Al), and 16 wt% to 20 wt% (e.g., 17 wt%, 18 ...16 wt% to 20 wt% (e.g., 17 wt%, 18 wt%) of magnesium (Mg), 1 wt% to 3 wt% (e.g., 1.5 wt%, 2 wt%, or 2.5 wt%) of aluminum (Al), 16 wt% to 20 wt% (e.g., 17 wt%, 18 wt%) of sodium (Na), 16 wt% to 20 wt% (e.g., 17 wt%, 18 wt%) of sodium (Na), 16 wt% to 20 wt% (e.g., 17 wt%, 18 wt%) of The blast furnace slag contains 19 wt% (t%) of silicon (Si), 0.05 wt% to 0.3 wt% (e.g., 0.1 wt%, 0.15 wt%, 0.2 wt%, or 0.25 wt%) of potassium (K), and 70 wt% to 80 wt% (e.g., 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, or 79 wt%) of calcium (Ca), based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium in the blast furnace slag. The elemental contents of the blast furnace slag and reducing slag can be determined using X-ray fluorescence spectrometer (XRF).

[0033] According to embodiments of the present invention, the particle size distribution D90 value of the blast furnace slag can be from 40 μm to 90 μm, for example, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, or 85 μm. According to embodiments of the present invention, the particle size distribution D90 value of the reducing slag can be from 50 μm to 100 μm, for example, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, or 95 μm. Here, particle size distribution D90 indicates that 90% of the powder volume has a diameter smaller than the value defined by D90. According to embodiments of the present invention, the particle size distribution D90 is determined according to the method specified in ISO 13322-1:2004.

[0034] According to embodiments of the present invention, the waste alkaline solution may be a sodium-containing aqueous solution derived from industrial waste alkaline solution generated during the pretreatment of dust collection ash. For example, the waste alkaline solution may be semiconductor grinding waste alkaline solution, aluminum slag regeneration alkaline solution, ceramic process cleaning waste alkaline solution, or a combination thereof. According to embodiments of the present invention, the waste alkaline solution may contain sodium ions, and the sodium ion concentration of the waste alkaline solution may be from about 100,000 ppm to 150,000 ppm, such as 105,000 ppm, 110,000 ppm, 115,000 ppm, 120,000 ppm, 125,000 ppm, 130,000 ppm, 135,000 ppm, 140,000 ppm, or 145,000 ppm. When the sodium ion concentration of the waste alkali solution is too low, the amount of waste alkali solution added to the concrete mix needs to be increased, leading to a decrease in the alkali equivalent concentration. This not only increases the curing time of the concrete mix but also results in concrete with more porosity, reducing its compressive strength. Conversely, when the sodium ion concentration of the waste alkali solution is too high, the amount added to the concrete mix needs to be reduced, leading to an increase in the alkali equivalent concentration. This tends to result in a shorter curing time for the concrete mix, affecting the formation of calcium aluminum silicate within the concrete.

[0035] According to embodiments of the present invention, since the waste alkali solution can be derived from industrial waste alkali, it may contain other cations besides sodium ions. The total concentration of these cations, excluding sodium ions, can be from approximately 5,000 ppm to 30,000 ppm, for example, 8,000 ppm, 10,000 ppm, 15,000 ppm, 20,000 ppm, or 25,000 ppm. These cations, excluding sodium ions, can be lead ions, cadmium ions, chromium ions, selenium ions, copper ions, barium ions, arsenic ions, mercury ions, or combinations thereof. Because the concrete mixture of the present invention forms gel-like calcium aluminum silicate during the curing process, it increases the structural density of the resulting concrete, helping to fix and coat heavy metals and prevent the release of heavy metals (e.g., lead, cadmium, chromium, arsenic, mercury). Therefore, even if the waste alkali solution used has a high concentration of heavy metal ions, the concrete of the present invention still has an extremely low concentration of heavy metal leaching, effectively solving the problem of waste disposal. According to an embodiment of the present invention, the ion concentration of the waste alkaline solution can be determined using an inductively coupled plasma optical emission spectrometer (ICP-OES).

[0036] According to embodiments of the present invention, the weight ratio of the waste alkali solution to the cementitious material in the concrete mixture can be approximately 3:10 to 5:10, for example, 3.5:10, 4:10, or 4.5:10. When the amount of waste alkali solution is too low, in addition to the concrete mixture being less likely to mix evenly, it can easily lead to a shortened curing time of the concrete mixture, affecting the formation of calcium aluminum silicate in the concrete. When the amount of waste alkali solution is too high, the water content of the concrete mixture is too high, resulting in increased porosity in the resulting concrete and a reduction in the compressive strength of the concrete.

[0037] According to embodiments of the present invention, the alkali equivalent concentration (eq / L) of the waste alkaline solution can be from 2.45 eq / L to 2.65 eq / L, for example, 2.50 eq / L, 2.55 eq / L, or 2.60 eq / L. When the alkali equivalent concentration is too low, in addition to increasing the curing time of the concrete mixture, it will also result in the concrete having more porosity, reducing the compressive strength of the concrete. When the alkali equivalent concentration is too high, the violent reaction leads to a shorter curing time for the concrete mixture, affecting the formation of calcium aluminum silicate within the concrete.

[0038] According to embodiments of the present invention, the concrete mixture may further include oxide slag derived from industrial waste, such as oxide sand slag, oxide slag aggregate (partially sized), oxide slag aggregate (six parts sized), or a combination thereof. According to embodiments of the present invention, the oxide slag may be glass fragments, aluminum slag aggregate, incinerator fly ash aggregate, or a combination thereof. According to embodiments of the present invention, since oxide slag generally has a rough surface, the contact area with the inorganic polymer (obtained by recombining / dehydration / polymerization of the cementing material) is increased, improving the bonding ability of the oxide slag and thus increasing the compressive strength.

[0039] According to embodiments of the present invention, the oxide residue comprises 5 wt% to 13 wt% (e.g., 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, or 12 wt%) of magnesium (Mg), 3 wt% to 6 wt% (e.g., 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, or 5.5 wt%) of aluminum (Al), and 18 wt% to 21 wt% (e.g., 18.5 wt%, 19 wt%, or 19.5 wt%). The oxide slag contains 20 wt% to 20.5 wt% silicon (Si), 0.2 wt% to 0.5 wt% potassium (K) (e.g., 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%), and 64 wt% to 70 wt% calcium (Ca) (e.g., 65 wt%, 66 wt%, 67 wt%, 68 wt%, or 69 wt%), based on the total weight of magnesium, aluminum, silicon, potassium, and calcium in the oxide slag. According to embodiments of the invention, the particle size distribution D90 value of the oxide slag can be from about 500 μm to 3 cm, for example 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 1 cm, 1.5 cm, 2 cm, or 2.5 cm. The elemental content of the oxide residue can be determined using X-ray fluorescence spectrometer (XRF). According to embodiments of the present invention, the weight ratio of the oxide residue to the cementitious material can be from 1:100 to 4:1, for example, 1:50, 1:20, 1:10, 1:5, 1:3, 1:2, 1:1, 2:1, or 3:1. When the amount of oxide residue added is too high, the resulting concrete structure is less dense (i.e., the porosity increases), leading to insufficient compressive strength.

[0040] According to embodiments of the present invention, the concrete mixture of the present invention may be composed of the cementitious material, waste alkali solution, and oxide slag, wherein the cementitious material, waste alkali solution, and oxide slag are all industrially recycled waste materials. According to embodiments of the present invention, the blast furnace slag, reduction slag, and oxide slag are all industrial waste materials produced by electric arc furnaces in steel plants. According to embodiments of the present invention, the concrete mixture of the present invention does not contain natural stone. Compared with the concrete of the present invention, since natural stone generally has a smooth surface (with low surface roughness), the contact area with inorganic polymers (obtained by recombining / dehydration / polymerization of cementitious materials) is reduced, therefore concrete prepared using natural stone exhibits poor compressive strength. Based on the above, the raw materials used in the concrete of the present invention are all recycled materials, thus having advantages such as low carbon emissions, low cost, and resource recycling of waste.

[0041] To make the above-mentioned and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings.

[0042] Table 1 lists the compositional analysis of blast furnace slag, reducing slag, silica sand, oxide slag three-part stone, and oxide slag six-part stone used in the embodiments and comparative examples of the present invention, as well as the compositional analysis of natural sand and natural stone used in the comparative examples (listing the contents of sodium, magnesium, aluminum, silicon, potassium, and calcium, based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium) (elemental analysis was performed using an X-ray fluorescence spectrometer (XRF). Furthermore, Table 1 lists the particle size distribution D90 values ​​of blast furnace slag, reducing slag, silica sand, oxide slag three-part stone, and oxide slag six-part stone used in the embodiments and comparative examples of the present invention, as well as the particle size distribution D90 values ​​of natural sand and natural stone used in the comparative examples (particle size distribution D90 was determined according to the method specified in ISO 13322-1:2004).

[0043] Table 1

[0044]

[0045]

[0046] Example 1

[0047] 67.14 parts by weight of blast furnace slag, 32.89 parts by weight of reducing slag, and 40 parts by weight of dust ash filtrate (an aqueous solution containing sodium sulfate, with a sodium sulfate concentration of approximately 17.63 wt%) were added to a mixing tank and thoroughly mixed to obtain concrete mixture (1). Next, the concrete mixture (1) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature (the initial and final setting times of the concrete mixture were observed to be 73 minutes and 93 minutes, respectively). After curing for 1 day and demolding, a concrete column (1) was obtained.

[0048] Example 2

[0049] Example 2 was prepared according to the method for preparing the concrete mixture (1) described in Example 1, except that the amount of dust filtrate was increased from 40 parts by weight to 45 parts by weight to obtain the concrete mixture (2). Next, the concrete mixture (2) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (2) was obtained.

[0050] Example 3

[0051] Example 3 was prepared according to the method for preparing the concrete mixture (1) described in Example 1, except that the amount of dust filtrate was increased from 40 parts by weight to 50 parts by weight, resulting in a concrete mixture (3). Next, the concrete mixture (3) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (3) was obtained.

[0052] Comparative Example 1

[0053] Comparative Example 1 was prepared according to the method for preparing the concrete mixture (4) described in Example 1, except that the dust filtrate was replaced with pure water to obtain the concrete mixture (4). Next, the concrete mixture (4) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature (the initial setting and final setting times of the concrete mixture were observed to be 600 minutes and 1140 minutes, respectively). After curing for 1 day and demolding, a concrete column (4) was obtained.

[0054] Comparative Example 2

[0055] Comparative Example 2 was prepared according to the method for preparing the concrete mixture (1) described in Example 1, except that the dust filtrate was replaced with pure water and 1 part by weight of sodium hydroxide (NaOH) was added to obtain the concrete mixture (5). Next, the concrete mixture (5) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (5) was obtained.

[0056] Comparative Example 3

[0057] Comparative Example 3 was prepared according to the method for preparing the concrete mixture (1) described in Example 1, except that the dust filtrate was replaced with pure water, and 0.67 parts by weight of sodium metasilicate and 1 part by weight of sodium hydroxide were added to obtain concrete mixture (6). Next, the concrete mixture (6) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (6) was obtained.

[0058] Comparative Example 4

[0059] Comparative Example 4 was prepared according to the method for preparing the concrete mixture (1) described in Example 1, except that the dust filtrate was replaced with pure water, and 1.37 parts by weight of sodium metasilicate and 1 part by weight of sodium hydroxide were added to obtain concrete mixture (7). Next, the concrete mixture (7) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (7) was obtained.

[0060] Comparative Example 5

[0061] Comparative Example 5 was prepared according to the method for preparing the concrete mixture (1) described in Example 1, except that the dust filtrate was replaced with pure water, and 2.73 parts by weight of sodium metasilicate and 1 part by weight of sodium hydroxide were added to obtain concrete mixture (8). Next, the concrete mixture (8) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (8) was obtained.

[0062] Table 2 shows the components and dosages used to form the concrete mixture in Examples 1-3 and Comparative Examples 1-5, as well as the converted alkali equivalent concentrations.

[0063] Table 2

[0064]

[0065]

[0066] Elemental analysis of concrete columns (1)-(3) was performed using an X-ray fluorescence spectrometer (XRF) to confirm the content of sodium, magnesium, aluminum, silicon, potassium and calcium in the concrete columns (1)-(3). The results are shown in Table 3.

[0067] Table 3

[0068]

[0069]

[0070] Next, the concrete column (1) was analyzed using an X-ray diffractometer (XRD). The obtained X-ray diffractogram showed characteristic peaks of calcium aluminum silicate (Ca3Al2(SiO4)3) at characteristic diffraction angles (2θ) of 43.4 to 44.5 degrees, and characteristic peaks of calcium silicate (Ca2(SiO4)3) at characteristic diffraction angles (2θ) of 31.9 to 32.2 degrees. Then, the integrated intensity (S1) of the characteristic peaks at diffraction angles (2θ) of 43.4 to 44.5 degrees and the integrated intensity (S2) of the characteristic peaks at diffraction angles (2θ) of 31.9 to 32.2 degrees were calculated. The ratio of integrated intensity (S1) to integrated intensity (S2) (S1 / S2) was calculated, and the results are shown in Table 4. In addition, the concrete column (4) was analyzed using an X-ray diffractometer (XRD). The obtained X-ray diffractogram showed that the concrete column (4) did not exhibit characteristic peaks at characteristic diffraction angles (2θ) of 43.4 to 44.5 degrees, but only at characteristic diffraction angles (2θ) of 31.9 to 32.2 degrees, representing calcium silicate (Ca2(SiO4)3). Next, the integrated intensity (S2) of the characteristic peaks at diffraction angles (2θ) of 31.9 to 32.2 degrees was calculated, and the results are shown in Table 4.

[0071] Table 4

[0072]

[0073] Next, on the 7th and 28th day after curing of concrete columns (1)-(8), the compressive strength of concrete was measured, and the results are shown in Table 5. The compressive strength of concrete was measured according to the method specified in ASTM C109 (sample size was 50mm x 50mm x 50mm).

[0074] Table 5

[0075]

[0076]

[0077] As shown in Tables 2 to 5, the concrete column (1) prepared in Example 1 uses blast furnace slag and reducing slag (containing silicon, aluminum and calcium components) as the source of inorganic polymers. At the same time, it is combined with industrial waste alkali filtrate (i.e. dust ash filtrate) to provide alkali activation effect, so that the metal oxides such as silicon oxide (SiO2), aluminum oxide (Al2O3), calcium oxide (CaO), and magnesium oxide (MgO) in blast furnace slag and reducing slag are activated and reorganized by alkali and undergo polymerization reaction, so that the resulting inorganic polymer has a high-strength gel-like calcium aluminosilicate (CASO) (as can be seen from the X-ray diffraction pattern, the concrete column (1) has the characteristic peak of calcium aluminosilicate (Ca3Al2(SiO4)3), and the ratio of the integral intensity (S1) of the characteristic peak of calcium aluminosilicate to the integral intensity (S2) of the characteristic peak of calcium silicate (S1 / S2) can reach about 0.1). After dehydration, the concrete column solidifies through polycondensation (exhibiting a relatively short curing time) and forms an ionic bond structure at room temperature. The concrete column (1) was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 2 As shown. By Figure 2 It can be seen that the inorganic polymer in the concrete column (1) has a relatively dense layered microstructure (density of about 2.4 g / cm³). 3 With an average pore size of approximately 0.42 μm, it exhibits excellent compressive strength (as shown in Table 5) and can physically encapsulate heavy metals contained within concrete columns.

[0078] In contrast, the concrete column (4) prepared in Comparative Example 1, due to the use of pure water instead of dust ash filtrate, was cured in an environment with an alkali equivalent concentration of 0%, failing to generate a high-strength gel-like calcium aluminosilicate (CASO) (as can be seen from the X-ray diffraction pattern, the concrete column (4) does not have the characteristic peaks of calcium aluminosilicate (Ca3Al2(SiO4)3)) (i.e., a highly dense inorganic polymer gel cannot be obtained). The concrete column (4) was observed using a scanning electron microscope (SEM), and the results are as follows. Figure 3 As shown. By Figure 3 It is known that, since blast furnace slag cannot react with reducing slag to form an inorganic polymer with gel-like calcium aluminum silicate, the concrete column (4) exhibits a granular microstructure (density of approximately 2.2 g / cm³). 3The average pore size is approximately 2.196 μm, resulting in poor compressive strength (as shown in Table 5), and the loose structure makes it easy for heavy metal elements contained in the concrete column to diffuse out. In addition, the concrete mixture (4) described in Comparative Example 1 requires an extremely long curing time.

[0079] Furthermore, Fourier-transform infrared spectroscopy (FTIR) was used to measure the concrete column (1) and concrete column (4), respectively. The results show that, compared to the concrete column (4) described in Comparative Example 1, the concrete column (1) described in Example 1 is located at 748 cm. -1 A distinct peak appears, characteristic of short-bonded Si-O / Al-O, indicating the presence of silicon-oxygen (Si-O) or aluminum-oxygen (Al-O) bonds in the concrete column (1). Furthermore, the concrete column (1) described in Example 1 shows a peak at 1018 cm⁻¹. -1 and 1108cm -1 All samples exhibited distinct absorption peaks, confirming the reaction between blast furnace slag and reducing slag, resulting in a change or recombination of the gel structure to form a Si-OT (T is SiO4 or AlO4) structure. The Fourier transform infrared spectra of the concrete columns described in Example 1 and Comparative Example 1 show that adding dust ash filtrate as an alkali activator during concrete preparation increases the stretching vibration of the main Si-OT peak, making the bonding peaks (silicon-oxygen (Si-O) or aluminum-oxygen (Al-O) bonds) more pronounced. Combined with the results shown in Table 5, it can be seen that when the alkalinity is high (i.e., dust ash filtrate replaces water), the stretching vibration of the Si-OT peak increases (i.e., at 1018 cm⁻¹). -1 and 1108cm -1 The characteristic peaks of the concrete column are significantly increased, and the compressive strength of the resulting concrete column is also increased accordingly.

[0080] Compared to Comparative Example 2, Examples 1 to 3 use dust ash filtrate instead of expensive chemical alkali, which not only effectively solves the waste disposal problem, but also the industrial waste alkali exhibits a lower exothermic rate compared to chemical alkali, avoiding excessively short curing time that reduces the formation of gel-like calcium aluminum silicate in the inorganic polymer. Therefore, the concrete columns described in Examples 1 to 3 have stronger compressive strength. Furthermore, even if the alkali equivalent used in Comparative Example 2 is increased (i.e., Comparative Examples 3 to 5), the compressive strength of the resulting concrete columns is still lower than that of the concrete columns described in this invention (as shown in Tables 2 and 5). As can be seen from Tables 2 and 5, the compressive strength of the concrete columns (1) to (3) obtained in Examples 1 to 3 is affected by the liquid-cement ratio in the concrete mixture (i.e., the ratio of the weight of dust ash filtrate to the total weight of blast furnace slag and reducing slag).

[0081] Example 4

[0082] 64.49 parts by weight of blast furnace slag, 30.51 parts by weight of reducing slag, 107.54 parts by weight of oxidized sand slag, 108.72 parts by weight of oxidized slag (partial slag), 131.79 parts by weight of oxidized slag (partial slag), and 40 parts by weight of dust collection filtrate (an aqueous solution containing sodium sulfate, with a sodium sulfate concentration of approximately 17.63 wt%) were added to a mixing tank and thoroughly mixed to obtain concrete mixture (9). Next, the concrete mixture (9) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (9) was obtained.

[0083] Example 5

[0084] 52.20 parts by weight of blast furnace slag, 47.80 parts by weight of reducing slag, 80.78 parts by weight of oxidized sand slag, 81.67 parts by weight of oxidized slag (partial slag), 99 parts by weight of oxidized slag (partial slag), and 40 parts by weight of dust ash filtrate (an aqueous solution containing sodium sulfate, with a sodium sulfate concentration of approximately 17.63 wt%) were added to a mixing tank and thoroughly mixed to obtain a concrete mixture (10). Next, the concrete mixture (10) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (10) was obtained.

[0085] Example 6

[0086] 38.14 parts by weight of blast furnace slag, 61.86 parts by weight of reducing slag, 59.02 parts by weight of oxidized sand slag, 59.67 parts by weight of oxidized slag (partial slag), 72.33 parts by weight of oxidized slag (partial slag), and 40 parts by weight of dust collection filtrate (an aqueous solution containing sodium sulfate, with a sodium sulfate concentration of approximately 17.63 wt%) were added to a mixing tank and thoroughly mixed to obtain concrete mixture (11). Next, the concrete mixture (11) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (11) was obtained.

[0087] Comparative Example 6

[0088] 64.49 parts by weight of blast furnace slag, 30.51 parts by weight of reduction slag, 107.54 parts by weight of natural sand, 240.51 parts by weight of natural slag, and 40 parts by weight of dust ash filtrate (an aqueous solution containing sodium sulfate, with a sodium sulfate concentration of approximately 17.63 wt%) were added to a mixing tank and thoroughly mixed to obtain a concrete mixture (12). Next, the concrete mixture (12) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (12) was obtained.

[0089] Comparative Example 7

[0090] 64.49 parts by weight of blast furnace slag, 30.51 parts by weight of reducing slag, 107.54 parts by weight of oxidized sand slag, 108.72 parts by weight of oxidized slag (3 parts by weight), 131.79 parts by weight of oxidized slag (6 parts by weight), 9.61 parts by weight of sodium metasilicate, 3.50 parts by weight of sodium hydroxide, and 40 parts by weight of pure water were added to a mixing tank and thoroughly mixed to obtain concrete mixture (13). Next, the concrete mixture (13) was poured into a column mold (10 cm in diameter and 20 cm in length) and dried at room temperature. After curing for 1 day and demolding, a concrete column (13) was obtained.

[0091] The components and dosages used to form the concrete mixture in Examples 4-6 and Comparative Examples 6 and 7, as well as the converted alkali equivalent concentrations, are shown in Table 6.

[0092] Table 6

[0093]

[0094]

[0095] Elemental analysis was performed on concrete columns (9) to (11) using an X-ray fluorescence spectrometer (XRF) to confirm the content of sodium, magnesium, aluminum, silicon, potassium, and calcium in the concrete columns (9) to (11). The results are shown in Table 7.

[0096] Table 7

[0097]

[0098]

[0099] Next, the concrete column (11) described in Example 6 was analyzed using an X-ray diffractometer (XRD). The obtained X-ray diffractogram showed characteristic peaks of calcium aluminum silicate (Ca3Al2(SiO4)3) at characteristic diffraction angles (2θ) of 43.4 to 44.5 degrees, and characteristic peaks of calcium silicate (Ca2(SiO4)3) at characteristic diffraction angles (2θ) of 31.9 to 32.2 degrees. Next, the integrated intensity (S1) of the characteristic peak of the concrete column (11) at a diffraction angle (2θ) of 43.4 to 44.5 degrees and the integrated intensity (S2) of the characteristic peak of the concrete column (11) at a diffraction angle (2θ) of 31.9 to 32.2 degrees were calculated, and the ratio of integrated intensity (S1) to integrated intensity (S2) (S1 / S2) was calculated. The results are shown in Table 8. In addition, the concrete column (13) described in Comparative Example 7 was analyzed using an X-ray diffractometer (XRD). From the obtained X-ray diffraction pattern, it can be seen that the concrete column (13) did not show a characteristic peak at a characteristic diffraction angle (2θ) of 43.4 to 44.5 degrees, but only a characteristic peak of calcium silicate (Ca2(SiO4)3) appeared at a characteristic diffraction angle (2θ) of 31.9 to 32.2 degrees. Next, the integral strength (S2) of the concrete column (13) at the characteristic peak with a diffraction angle (2θ) of 31.9 degrees to 32.2 degrees was calculated, and the results are shown in Table 8.

[0100] Table 8

[0101]

[0102] Next, the compressive strength of concrete columns (9) to (13) was measured on the 7th and 28th days after curing, respectively. The results are shown in Table 9. The compressive strength of concrete was measured according to the method specified in ASTM C109.

[0103] Table 9

[0104]

[0105] As shown in Tables 6 to 9, since the concrete column (9) prepared in Example 4 uses blast furnace stone and reducing slag (containing silicon, aluminum and calcium components) as the source of inorganic polymer, and is combined with industrial waste alkali filtrate (i.e. dust ash filtrate) to provide alkali activation, the metal oxides such as silicon oxide (SiO2), aluminum oxide (Al2O3), calcium oxide (CaO), and magnesium oxide (MgO) in blast furnace stone and reducing slag can be activated and reorganized by alkali and undergo exothermic dehydration to carry out polymerization reaction, so that the resulting inorganic polymer has a high-strength gel-like calcium aluminosilicate (CASO) (as can be seen from the X-ray diffraction pattern, the concrete column (1) has the characteristic peak of calcium aluminosilicate (Ca3Al2(SiO4)3), and the ratio of the integral intensity (S1) of the characteristic peak of calcium aluminosilicate to the integral intensity (S2) of the characteristic peak of calcium silicate (S1 / S2) can reach about 0.44). Furthermore, Example 4 further incorporates waste stone materials (such as oxidized sand, oxidized slag three-part stone, and oxidized slag six-part stone) to replace natural sand and gravel in the preparation of concrete columns, which not only effectively solves the waste disposal problem but also allows the concrete columns to maintain high compressive strength.

[0106] Furthermore, after 28 days of curing, the concrete column (9) prepared in Example 4 was subjected to heavy metal release testing, and the results are shown in Table 10. The heavy metal release testing was conducted according to the method specified in EPA Method 1311. The ion content of the dust filtrate was analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES) (Agilent 5100).

[0107] Table 10

[0108]

[0109] As shown in Table 10, the concrete column (9) does have a coating effect on heavy metal ions, which significantly reduces the concentration of heavy metal leaching, thus meeting the regulatory requirements.

[0110] Furthermore, as shown in Table 9, compared with Comparative Example 6 which uses natural sand and gravel, the compressive strength and density of the concrete columns (9) and (10) prepared in Examples 4 and 5 are higher than those of the inorganic polymer concrete made from natural sand and gravel. The main reason is that the surface of the oxidized slag sand is rougher than that of natural sand and gravel, thus increasing the contact area with the inorganic polymer obtained by the reaction of blast furnace slag and reducing slag, improving the bonding ability of the oxidized slag sand, and thus improving the compressive strength of the concrete column.

[0111] In summary, this invention utilizes industrial by-products (or waste) to obtain environmentally friendly concrete that can cure at room temperature, possesses high compressive strength, and has low toxicity. Furthermore, by using waste alkali solution as an alkali activator (replacing expensive chemical alkalis) and mixing it with the cementitious material in a specific ratio, the metal oxides such as silicon dioxide (SiO2), aluminum oxide (Al2O3), calcium oxide (CaO), and magnesium oxide (MgO) in the cementitious material undergo alkali activation, recombination, and polymerization at room temperature. This results in an inorganic polymer containing highly dense gel-like calcium aluminum silicate, which helps to fix and encapsulate heavy metals, preventing their release. Therefore, the concrete mixture of this invention has an appropriate curing speed at room temperature, and the resulting concrete exhibits low toxicity, resistance to expansion, and high compressive strength.

[0112] Although the present invention has been disclosed above with reference to several embodiments, it is not intended to limit the present invention. Anyone with common knowledge in the art can make any modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the appended claims.

Claims

1. A type of concrete, comprising: The concrete contains 11 wt% to 20 wt% sodium (Na), 3 wt% to 6 wt% magnesium (Mg), 7 wt% to 11 wt% aluminum (Al), 15 wt% to 22 wt% silicon (Si), 0.4 wt% to 0.7 wt% potassium (K), and 49 wt% to 53 wt% calcium (Ca), based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium in the concrete, and the concrete contains calcium aluminum silicate compounds.

2. The concrete according to claim 1, wherein the characteristic peak value (2θ) of the calcium aluminum silicate compound in the X-ray diffraction pattern of the concrete is 43.4 degrees to 44.5 degrees.

3. The concrete according to claim 1, wherein the characteristic peak value (2θ) of the X-ray diffraction pattern of the concrete has a first integrated intensity (S1) at 43.4 degrees to 44.5 degrees, and the characteristic peak value (2θ) of the X-ray diffraction pattern of the concrete has a second integrated intensity (S2) at 31.9 degrees to 32.2 degrees, wherein the ratio of the first integrated intensity to the second integrated intensity (S1 / S2) is 0.03 to 0.

15.

4. The concrete according to claim 1, wherein the Fourier transform infrared spectrum of the concrete is at 1,000 cm⁻¹ -1 Up to 1,150cm -1 It has characteristic peaks within the range.

5. A method for preparing concrete, comprising the following steps: A concrete mixture is provided, wherein the concrete mixture comprises a binder and a waste alkali solution, wherein the binder comprises 35 to 70 parts by weight of blast furnace slag and 30 to 65 parts by weight of reducing slag; the waste alkali solution contains sodium ions, and the concentration of the sodium ions is 100,000 ppm to 150,000 ppm; and the weight ratio of the waste alkali solution to the binder is 3:10 to 5:

10. The concrete mixture is subjected to a casting process to obtain a blank; and The green body is cured at room temperature to obtain the concrete as described in claim 1.

6. The method for preparing concrete according to claim 5, wherein the waste alkaline solution further comprises cations other than sodium ions, wherein the total concentration of the cations other than sodium ions is from 5,000 ppm to 30,000 ppm.

7. The method for preparing concrete according to claim 5, wherein the waste alkaline solution is semiconductor grinding waste alkaline solution, aluminum slag regeneration alkaline solution, ceramic process cleaning waste alkaline solution, or a combination thereof.

8. The method for preparing concrete according to claim 5, wherein the blast furnace slag comprises 0.1 wt% to 0.5 wt% sodium (Na), 5 wt% to 8 wt% magnesium (Mg), 13 wt% to 16 wt% aluminum (Al), 24 wt% to 27 wt% silicon (Si), 0.2 wt% to 0.7 wt% potassium (K), and 50 wt% to 55 wt% calcium (Ca), based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium in the blast furnace slag.

9. The method for preparing concrete according to claim 5, wherein the particle size distribution D90 value of the blast furnace stone is 40 μm to 90 μm.

10. The method for preparing concrete according to claim 5, wherein the reduced slag contains 0.2 wt% to 0.6 wt% sodium (Na), 3 wt% to 6 wt% magnesium (Mg), 1 wt% to 3 wt% aluminum (Al), 16 wt% to 20 wt% silicon (Si), 0.05 wt% to 0.3 wt% potassium (K), and 70 wt% to 80 wt% calcium (Ca), based on the total weight of sodium, magnesium, aluminum, silicon, potassium, and calcium in the reduced slag.

11. The method for preparing concrete according to claim 5, wherein the particle size distribution D90 value of the reduced slag is 50 μm to 100 μm.

12. The method for preparing concrete according to claim 5, wherein the concrete mixture further comprises slag monoxide.

13. The method for preparing concrete according to claim 12, wherein the weight ratio of the oxide residue to the cementitious material is from 1:100 to 400:

100.

14. The method for preparing concrete according to claim 12, wherein the precipitate comprises 5 wt% to 13 wt% magnesium (Mg), 3 wt% to 6 wt% aluminum (Al), 18 wt% to 21 wt% silicon (Si), 0.2 wt% to 0.5 wt% potassium (K), and 64 wt% to 70 wt% calcium (Ca), based on the total weight of magnesium, aluminum, silicon, potassium, and calcium in the precipitate.

15. The method for preparing concrete according to claim 12, wherein the particle size distribution D90 value of the oxide slag is 500 μm to 3 cm.

16. The method for preparing concrete according to claim 5, wherein the concrete mixture does not contain natural aggregate.

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