Hardened body using slag containing free MgO and method for manufacturing hardened body

Abstract

This invention provides a hardened body utilizing slag containing free MgO, such as steelmaking slag. This hardened body suppresses volume expansion caused by hydration reactions based on free MgO and addresses insufficient strength. The hardened body utilizing slag containing free MgO is manufactured by adding water to a mixture containing slag containing free MgO as a material, kneading the mixture, and then solidifying the mixture. In this hardened body, the unit amount of slag containing free MgO is 2000 kg / m³. 3 The following is the unit weight of alumina cement: 75 kg / m³ 3 Above and 200kg / m 3 The following unit weight of blast furnace slag powder is 330 kg / m³. 3 Above and 530kg / m 3 The following calculations use B2O3 as the unit amount for boron-containing substances, which is 0.5 kg / m³. 3 Above and 4.0 kg / m 3 the following.

Description

Technical Field

[0001] This invention relates to a hardened body manufactured using slag containing free MgO, such as steelmaking slag, as a material, and a method for manufacturing the hardened body. Background Technology

[0002] In the steelmaking process, to prevent MgO contained in refractory materials from dissolving into the slag during refining and causing refractory loss, MgO with a saturation solubility exceeding a certain level is sometimes added to the slag. The slag produced by such refining contains MgO remaining in an unreacted state from the refining process, as well as MgO that crystallizes during slag cooling. This unreacted MgO and crystallized MgO are referred to as free MgO.

[0003] As an attempt to fully utilize steelmaking slag, a hydrated hardened body of steelmaking slag has been used, for example, as disclosed in Patent Document 1. The hydrated hardened body described in Patent Document 1 comprises aggregate and binder material, which hardens upon the addition of water and mixing. The aggregate contains steelmaking slag containing unreacted CaO that has undergone a hydration reaction, and the binder material contains 50% by weight or more of a silica-containing substance with potential hydraulic properties and solidifies through a hydration reaction.

[0004] However, steelmaking slag containing free MgO has the property of expanding due to the long-term hydration reaction of free MgO. Therefore, there is a risk of expansion cracks in the hardened body, making it difficult to fully utilize it as a material for hydration hardening. Here, the hydration reaction of free MgO refers to the reaction in which free MgO in steelmaking slag comes into contact with moisture such as rainwater and seawater to form Mg(OH)2 (MgO + H2O → Mg(OH)2). Due to this reaction, the volume expands.

[0005] In the field of refractories, for example, the method for inhibiting the hydration of MgO by forming a crystalline film such as boric acid on the surface of a refractory, as disclosed in Patent Document 2, is well known. Patent Document 2 discloses a method for preventing the disintegration of basic refractory bricks, which includes forming a crystalline film of one or more of sulfate, boric acid, and borate on the surface of the basic refractory bricks. The film is formed by immersing the basic refractory bricks in an aqueous solution, or by coating the basic refractory bricks with the aqueous solution and then drying the aqueous solution. The aqueous solution is an aqueous solution in which the value of the mathematical expression 100c / (a×b) has a value of 0.2 or more and 1.0 or less, given that the weight of water is a (g), the saturated solubility is b (g), and the weight of the solute is c (g).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 3582263

[0009] Patent Document 2: Japanese Patent Application Publication No. 8-169783 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, based on the aforementioned existing technology, an attempt was made to prepare a slag hardened body containing B2O3 to suppress the hydration expansion of free MgO, using steelmaking slag containing free MgO as the material. The result was that the compressive strength of the obtained hardened body after 28 days was less than 20 N / mm². 2 It is not tolerable as a substitute for cement / concrete.

[0012] The present invention was made in view of the above circumstances, and its object is to provide a hardened body utilizing slag containing free MgO, such as steelmaking slag, which suppresses volume expansion caused by hydration reaction based on free MgO and solves the problem of insufficient strength of the hardened body. In addition, a method for manufacturing the hardened body is also provided.

[0013] Problem Solving Methods

[0014] The main idea of ​​the present invention for solving the above problems is as follows.

[0015] [1] A hardened body utilizing slag containing free MgO,

[0016] In the aforementioned hardened body, the slag containing free MgO has a unit content of 2000 kg / m³. 3 The following is the unit weight of alumina cement: 75 kg / m³ 3 Above and 200kg / m 3 The following unit weight of blast furnace slag powder is 330 kg / m³. 3 Above and 530kg / m 3 The following calculations use B2O3 as the unit amount for boron-containing substances, which is 0.5 kg / m³. 3 Above and 4.0 kg / m 3 the following.

[0017] [2] A method for manufacturing a hardened body using slag containing free MgO, wherein the method comprises:

[0018] The unit quantity of slag containing free MgO is set at 2000 kg / m³. 3 The unit weight of alumina cement is set at 75 kg / m³. 3 Above and 200kg / m 3Hereinafter, the unit quantity of blast furnace slag powder is set at 330 kg / m³. 3 Above and 530kg / m 3 In the following, the unit amount of boron-containing substances is converted to B2O3 and set to 0.5 kg / m³. 3 Above and 4.0 kg / m 3 The following mixture is formed.

[0019] Water is added to the mixture, and the mixture is kneaded. Then, the kneaded mixture is allowed to solidify.

[0020] [3] A method for manufacturing a hardened body using slag containing free MgO, wherein the method comprises:

[0021] Slag containing free MgO is impregnated in a solution containing dissolved boron, or a solution containing dissolved boron is sprayed onto slag containing free MgO, so that boron-containing substances, calculated as B2O3, at least 0.10% by mass, are pre-adhered to the surface of the slag containing free MgO.

[0022] The unit quantity of the above-mentioned slag containing free MgO, which is pre-attached with boron-containing substances, is set at 2000 kg / m³. 3 The following is an example of setting the amount of boron-containing material adhering to the surface of the slag to 0.5 kg / m³ (converted to B₂O₃). 3 Above and 4.0 kg / m 3 The unit weight of alumina cement is set at 75 kg / m³. 3 Above and 200kg / m 3 Hereinafter, the unit quantity of blast furnace slag powder is set at 330 kg / m³. 3 Above and 530kg / m 3 The following mixture is formed.

[0023] Water is added to the mixture, and the mixture is kneaded. Then, the kneaded mixture is allowed to solidify.

[0024] The effects of the invention

[0025] According to the present invention, a hardened body can be obtained that does not exhibit expansion cracks caused by hydration expansion based on free MgO even when using slag containing free MgO, such as steelmaking slag, as a material during the manufacture of the hardened body, and has sufficient strength as a substitute for cement / concrete. Detailed Implementation

[0026] Hereinafter, an example of this embodiment will be described.

[0027] The hardened body (hereinafter also referred to as "slag hardened body") utilizing slag containing free MgO in this embodiment is manufactured by adding water to a mixture containing slag containing free MgO as a material, kneading it, and then allowing the kneaded mixture to solidify. In this hardened body, the unit amount of slag containing free MgO is 2000 kg / m³. 3 The following is the unit weight of alumina cement: 75 kg / m³ 3 Above and 200kg / m 3 The following unit weight of blast furnace slag powder is 330 kg / m³. 3 Above and 530kg / m 3 The following calculations use B2O3 as the unit amount for boron-containing substances, which is 0.5 kg / m³. 3 Above and 4.0 kg / m 3 The following applies. Depending on the requirements, slag or natural aggregates that do not contain free MgO can be used as materials. Natural aggregates include, for example, "gravel and sand".

[0028] The slag hardened body of this embodiment is characterized in that, on average, per 1m 3 The hardened body contains 0.5 kg / m³ of B₂O₃. 3 Above and 4.0 kg / m 3 The following boron-containing substances are used. By adding boron-containing substances to slag containing free MgO, a crystalline film of boric acid or borate is formed on the surface of the free MgO in the slag. This crystalline film prevents the surface of the free MgO from contacting moisture in the gaseous atmosphere, such as the air. In other words, the crystalline film of boric acid or borate functions as a moisture-absorbing material, inhibiting the hydration of free MgO and preventing expansion cracks in the hardened slag body caused by the hydration expansion based on free MgO.

[0029] In the slag hardened body of this embodiment, the unit amount of boron-containing material used to suppress the hydration expansion of free MgO is set to 0.5 kg / m³ (converted to B₂O₃). 3 Above and 4.0 kg / m 3 The following is because the inventors discovered that the unit amount of boron-containing substances, converted to B2O3, is less than 0.5 kg / m³. 3 At that time, the effect of inhibiting hydration swelling was small; on the other hand, the concentration of B2O3 was greater than 4.0 kg / m³. 3 At that time, the hardened body will not solidify.

[0030] As a boron-containing substance, any substance in which boron is dissolved in water is acceptable, without any particular limitation. For example, boron trioxide (B2O3), boric acid (H3BO3), borax (Na2B4O5(OH)4·8H2O), and other boron oxides and boron compounds can be used.

[0031] Another feature of the slag hardened body of this embodiment is the use of alumina cement as a binder. The reason for using alumina cement is that: (1) it can suppress the expansion of free MgO in the slag hardened body without destroying the boric acid or borate crystal film on the surface of free MgO formed by boron-containing substances; and (2) the slag hardened body containing boron-containing substances can also obtain sufficient strength as a substitute for cement / concrete.

[0032] It can be assumed that in the slag hardened body with added boron-containing substances, a magnesium borate-based crystalline film is formed on the surface of free MgO.

[0033] In the combination of blast furnace slag micropowder, commonly used as a binder material in slag hardened bodies, and ordinary Portland cement, the high pH (hydrogen ion concentration index) of the ordinary Portland cement (approximately 12.7) causes magnesium borate crystals to dissolve within the film, reducing its effect on inhibiting the expansion of free MgO. Furthermore, B₂O₃, a boron-containing substance, acts as a setting delayer in cement and exhibits acidity; therefore, it hinders the supply of alkali required to express the potential hydraulic properties of the blast furnace slag micropowder, leading to delayed setting and reduced strength of the slag hardened body.

[0034] Therefore, in the slag hardened body of this embodiment, alumina cement, which has a lower pH than ordinary silicate cement, a faster hydration rate, and thus can suppress setting delay, is used as the binding material.

[0035] In the slag hardened body of this embodiment, the alumina cement in the slag hardened body is set to an average of 1m 3 75 kg / m³ of hardened slag 3 Above and 200kg / m 3 The following is because the unit weight of alumina cement is less than 75 kg / m³. 3 At that time, the compressive strength of the material after 28 days was 20 N / mm². 2 The following are difficult to use as a substitute for cement / concrete. Here, "age" refers to the number of days since the slag hardening body was cast. On the other hand, due to the high cost of alumina cement, it is unlikely to be used as a substitute if the mix exceeds 200 kg / m³. 3 If this is not done, the economic efficiency will decrease. Therefore, the unit yield of alumina cement is set at 200 kg / m³. 3 the following.

[0036] Alumina cement used in manufacturing the slag hardened body of this embodiment includes, for example, HI-ALUMINA CEMENT H manufactured by Denka Corporation.

[0037] In the slag hardened body of this embodiment, on average per 1m3 Hardened slag body combined with blast furnace slag micro powder 330kg / m 3 Above and 530kg / m 3 The following is because, by limiting the unit amount of blast furnace slag powder to this range, the quantitative balance between the amount of alkali ions provided by alumina cement and the amount of reactive SiO2 in the blast furnace slag powder with potential hydraulicity becomes appropriate, resulting in a hardened body with sufficient strength.

[0038] The blast furnace slag powder used in manufacturing the hardened slag body of this embodiment is obtained by pulverizing blast furnace water-crushed slag. Preferably, the blast furnace slag powder has a particle size of about 0.1 mm or less and a specific surface area of ​​about 3000 cm² based on Blaine's method. 2 / g or more. Additionally, if a specific surface area of ​​4000 cm² is used based on the Blaine method... 2 Blast furnace slag micro powder with a concentration of / g or higher has higher activity and is a further preferred option.

[0039] The slag containing free MgO used in manufacturing the slag-hardened body of this embodiment refers to slag in which periclase peaks are confirmed by X-ray diffraction. Slag generated during the smelting of high-chromium molten ferroalloys is particularly preferred. Examples of high-chromium molten ferroalloys include: chromium-containing molten pig iron, high-chromium molten steel (typically with a chromium content of 5% by mass or more, such as stainless steel), and chromium-containing master melts used to manufacture such high-chromium steel (e.g., molten ferroalloys smelted in an electric furnace or the like with a chromium concentration of 5% by mass or more and a carbon concentration of 1% by mass or more and less than 2% by mass).

[0040] For chromium-containing molten pig iron, smelting is typically carried out in electric arc furnaces, iron bath reduction furnaces, or vertical shaft reduction furnaces through the smelting and reduction of chromium ore. For high-chromium molten steel, smelting is carried out in primary refining furnaces such as electric arc furnaces, converters, and AOD furnaces, and secondary refining furnaces such as VOD furnaces, RH vacuum degassing devices, and ladle refining furnaces. In addition, the chromium-containing master melt used to manufacture high-chromium steel is mainly smelted in electric arc furnaces and converters.

[0041] In these smelting and refining furnaces, for molten reduction furnaces that moltenly reduce chromium ore, in order to protect the furnace refractory, an operation is performed to add MgO with a saturation solubility greater than that of the slag to the slag. Therefore, the resulting slag (chromium smelting slag) contains free MgO. Such slag is suitable for manufacturing the slag hardened body of this embodiment.

[0042] Although the free MgO content of the slag (referred to as "converter decarburization slag") produced when pure oxygen is supplied to the molten pig iron in the converter from top-blown lances or the like for decarburization refining of molten pig iron is lower than that of chromium smelting slag, it can still be used as slag containing free MgO when manufacturing the slag hardened body of this embodiment.

[0043] Furthermore, for the slag hardened body, strength is achieved by filling the gaps between aggregates such as slag with a paste-like component containing blast furnace slag powder, alumina cement, and water, thereby achieving bonding. In the slag hardened body of this embodiment, the unit amount of slag containing free MgO is limited to an average of 1 m³. 3 2000 kg / m³ of hardened slag 3 The following is because if the unit amount of slag containing free MgO exceeds 2000 kg / m³... 3 If the amount of blast furnace slag powder, alumina cement, and water in the hardened slag body decreases, the bonding force of the aggregate will decrease and the strength of the hardened slag body will decrease.

[0044] On the other hand, in the slag hardening body of this embodiment, there is no lower limit on the unit amount of slag containing free MgO. This is because slag containing free MgO functions as aggregate in the slag hardening body, but slag without free MgO or natural aggregate can also be used as materials as needed. Therefore, it is not necessary to technically limit the lower limit on the unit amount of slag containing free MgO. However, if the unit amount of slag is too small, it is not conducive to the effective utilization of slag. Therefore, it is preferable to have an average of 1 m³ of slag containing free MgO. 3 The unit weight of slag containing free MgO in the hardened slag body is set at 300 kg / m³. 3 Therefore, slag containing free MgO can be effectively utilized.

[0045] Furthermore, in the slag hardened body of this embodiment, a high-performance water-reducing agent is preferably incorporated. When manufacturing the slag hardened body, reducing the amount of water added during mixing can increase the strength of the slag hardened body. However, if the amount of water added during mixing is reduced, the material cannot be dispersed. The high-performance water-reducing agent is used to disperse the material while reducing the amount of water added. For example, a polycarboxylate-based high-performance water-reducing agent can be used. Generally, the amount of high-performance water-reducing agent used is preferably 0.3% by mass or more and 0.5% by mass or less, which is the sum of the unit amount of blast furnace slag powder and the unit amount of alumina cement.

[0046] Next, the method for manufacturing the hardened slag body according to this embodiment will be described. There are two methods for manufacturing the hardened slag body according to this embodiment.

[0047] The method for manufacturing a slag hardened body is as follows: the unit amount of slag containing free MgO is set at 2000 kg / m³. 3 The unit weight of alumina cement is set at 75 kg / m³. 3 Above and 200kg / m 3 Hereinafter, the unit quantity of blast furnace slag powder is set at 330 kg / m³. 3 Above and 530kg / m 3 In the following calculations, the unit amount of boron-containing substances is set to 0.5 kg / m³ using B₂O₃ as the conversion factor. 3 Above and 4.0 kg / m 3 Next, a mixture is formed, water is added to the mixture, and the mixture is kneaded. Then, the kneaded mixture is allowed to solidify.

[0048] In this case, slag or natural aggregates without free MgO can be used as materials, as needed. Additionally, an appropriate amount of high-performance water-reducing agent can be used.

[0049] Another method for manufacturing hardened slag is as follows: Slag containing free MgO is impregnated in a solution containing dissolved boron, or a mist of a solution containing dissolved boron is sprayed onto the slag containing free MgO, so that the boron-containing substance, calculated as B2O3, at least 0.10% by mass, is pre-adhered to the surface of the slag containing free MgO. Then, the unit weight of the slag containing free MgO pre-adhered with boron is set at 2000 kg / m³. 3 The following is an example of setting the amount of boron-containing material adhering to the surface of the slag to 0.5 kg / m³ (converted to B₂O₃). 3 Above and 4.0 kg / m 3 The unit weight of alumina cement is set at 75 kg / m³. 3 Above and 200kg / m 3 Hereinafter, the unit quantity of blast furnace slag powder is set at 330 kg / m³. 3 Above and 530kg / m 3 The mixture is then formed. Water is added to the mixture, and the mixture is kneaded. The kneaded mixture is then solidified. The reason for attaching boron-containing substances of 0.10% by mass (equivalent to B2O3) or more to the surface of slag containing free MgO beforehand is that when the boron content is less than 0.10% by mass (equivalent to B2O3), the effect of inhibiting hydration expansion is insufficient.

[0050] In this case, slag or natural aggregates without free MgO can be used as materials, depending on the need. Additionally, an appropriate amount of high-performance water-reducing agent can be used.

[0051] As explained above, according to this embodiment, when manufacturing slag hardened bodies, even when using slag containing free MgO, such as steelmaking slag, as a material, it is possible to obtain slag hardened bodies that do not experience expansion cracks caused by hydration expansion based on free MgO and have sufficient strength as a substitute for cement / concrete.

[0052] Example 1

[0053] The following describes this embodiment. In this embodiment, a hardened slag body was prepared using three types of slag (slag A to C) with the compositions shown in Table 1. It should be noted that in Table 1, "CaO / SiO2" represents the ratio of CaO concentration (mass%) to SiO2 concentration (mass%) in the slag (referred to as "basicity"), and "MgO" and "free MgO" represent the MgO concentration (mass%) and free MgO concentration (mass%) in the slag, respectively.

[0054] [Table 1]

[0055]

[0056] In the slag shown in Table 1, a hardened body (example of the present invention) was prepared by combining alumina cement, blast furnace slag powder, natural aggregate (coarse aggregate), boron-containing substances, high-performance water-reducing agent, and water in the unit amounts specified above within the scope of the present invention. In the example of the present invention, the unit amount of boron-containing substances converted from B2O3 was set to 0.5 kg / m³. 3 1.5kg / m 3 3.5kg / m 3 4.0kg / m 3 For the unit amount of boron-containing substances converted from B2O3, the unit amount of alumina cement is set to 75 kg / m³. 3 83kg / m 3 90kg / m 3 100kg / m 3 110kg / m 3 180kg / m 3 200kg / m 3 In addition, for comparison, hardened bodies with alumina cement content outside the scope of this invention, hardened bodies without boron-containing substances, and hardened bodies with a boron-containing substance content converted from B2O3 set at 4.5 kg / m³ were also manufactured. 3 The hardened body (comparative example). In this embodiment, boron trioxide (B2O3) was used as the boron-containing substance and dissolved in water used to manufacture the slag hardened body.

[0057] For the hardened specimens, two types were manufactured: one for strength testing and the other for expansion assessment. For the hardened specimens used for strength testing, after solidification, they were removed from the frame and cured in water at 20°C for 28 days. The compressive strength was then measured based on JIS A 1108. For the hardened specimens used for expansion assessment, after solidification, they were removed from the frame and cured in water at 20°C for 14 days. After curing, they were immersed in water at 80°C. The hardened specimens were observed 45 days after immersion to check for large cracks. A compressive strength of 20 N / mm² was used. 2 The above are considered acceptable. In the expansion assessment, cases without identified cracks are considered "acceptable," while cases with identified cracks are considered "unacceptable." A "cannot be determined" result in the compressive strength and expansion assessment column indicates that the material has not solidified or has undergone hydration expansion without forming a hardened body.

[0058] Table 2 shows the fit table of the test specimens made using slag A, as well as the results of the compressive strength and expansion determination.

[0059] [Table 2]

[0060]

[0061] In Comparative Examples 1-8 without added boron, cracks were detected after 45 days, indicating expansion of free MgO. The boron-containing substance was calculated to be 4.5 kg / m³ using B₂O₃ as the unit weight. 3 In Comparative Examples 9-15, the test specimens did not solidify, so compressive strength and expansion could not be measured.

[0062] In contrast, it was confirmed that the unit amount of boron-containing substances, converted to B2O3, was 0.5 kg / m³. 3 Above and 4.0 kg / m 3 In the following examples 1 to 28 of the present invention, there is no breakage; they are in an intact state.

[0063] In addition, it can be confirmed that the unit weight of alumina cement is 44 kg / m³. 3 In Comparative Example 1, the compressive strength was less than 20 N / mm. 2 However, the unit weight of alumina cement is 75 kg / m³. 3 In Examples 1 to 28 of the present invention above, the compressive strength exceeds 20 N / mm². 2 It can achieve strength equal to or higher than that of ordinary concrete.

[0064] Table 3 shows the fit table of the test specimens made using slag B, as well as the results of the compressive strength and expansion determination.

[0065] [Table 3]

[0066]

[0067] In Comparative Examples 16-23 without added boron, cracks were detected after 45 days, indicating expansion of free MgO. The boron-containing substance was calculated to be 4.5 kg / m³ using B₂O₃ as the unit weight. 3 In Comparative Examples 24-30, the test specimens did not solidify, so compressive strength and expansion could not be measured.

[0068] In contrast, it was confirmed that the unit amount of boron-containing substances, converted to B2O3, was 0.5 kg / m³. 3 Above and 4.0 kg / m 3 In the following examples 29 to 56 of the present invention, there is no breakage; they are in an intact state.

[0069] In addition, it can be confirmed that the unit weight of alumina cement is 44 kg / m³. 3 In Comparative Example 16, the compressive strength was less than 20 N / mm. 2 However, when the unit quantity of alumina cement is set at 75 kg / m³ 3 In Examples 29 to 56 of the present invention above, the compressive strength exceeds 20 N / mm². 2 It can achieve strength equal to or higher than that of ordinary concrete.

[0070] Table 4 shows the fit table of the test specimens made using slag C, as well as the results of the compressive strength and expansion determination.

[0071] [Table 4]

[0072]

[0073] Although the unit amount of slag C is 2000 kg / m³ 3 In comparative examples 31-38 (without added boron), cracks were confirmed after 45 days, indicating that free MgO had expanded. Although the slag C content was 2000 kg / m³... 3 The following calculations assume the unit amount of boron-containing substances is 4.5 kg / m³ (converted to B₂O₃). 3 In Comparative Examples 39–44, the test specimens did not solidify, so compressive strength and expansion could not be measured.

[0074] The unit quantity of slag C is set at 2379 kg / m³. 3 In Comparative Example 45, the paste composition containing water, blast furnace slag powder, and alumina cement was insufficient; therefore, the strength of the test specimen was low, with a compressive strength of less than 20 N / mm². 2 .

[0075] In contrast, it was confirmed that the unit quantity of slag C was set at 2000 kg / m³. 3The following calculations assume that the unit amount of boron-containing substances is 0.5 kg / m³, converted to B₂O₃. 3 Above and 4.0 kg / m 3 In the following examples 57-80 of the present invention, there is no breakage; they are in an intact state.

[0076] In addition, it can be confirmed that the unit weight of alumina cement is 44 kg / m³. 3 In comparative examples 31 and 35, the compressive strength was less than 20 N / mm. 2 However, when the unit quantity of alumina cement is set at 75 kg / m³ 3 In the above examples 57-80 of the present invention, the compressive strength exceeds 20 N / mm². 2 It can achieve strength equal to or higher than that of ordinary concrete.

[0077] Example 2

[0078] The following experiment was conducted: Three types of slag (slag A to C) shown in Table 1 were brought into contact with a boron-containing substance. A hardened body was manufactured using slag with the boron-containing substance pre-adhered to its surface. Boron trioxide (B₂O₃) was used as the boron-containing substance. This boron trioxide reagent was dissolved in 50 times its mass of water to prepare an aqueous solution (boric acid solution). This aqueous solution was sprayed onto the slag in a mist, allowing the boron-containing substance (boric acid) to adhere to the slag surface. The slag was then dried and used as the material for the hardened body.

[0079] In slag pre-attached with boron-containing substances of 0.10% by mass (equivalent to B2O3), a hardened body was manufactured by mixing alumina cement, blast furnace slag powder, natural aggregate (coarse aggregate), high-performance water-reducing agent, and water in unit amounts within the scope of the present invention (Example of the present invention). Additionally, for comparison, a hardened body with a boron-containing substance attachment amount outside the scope of the present invention was also manufactured (Comparative Example).

[0080] In addition, two types of hardened bodies were manufactured: one for strength measurement and the other for expansion determination. The compressive strength and expansion determination of the manufactured hardened bodies were performed under the same conditions as in Example 1 above.

[0081] Table 5 shows the fit table of the test specimens made using slag A, as well as the results of the compressive strength and expansion determination.

[0082] [Table 5]

[0083]

[0084] It was confirmed that the unit weight of alumina cement was set at 75 kg / m³. 3 Above and 200kg / m 3The following is defined as follows: the boron-containing material adhering to the slag surface is calculated as B2O3, which is 0.10% or more of the slag. The amount of boron-containing material in the hardened body, calculated as the product of the unit amount of slag and the mass ratio of the adhering boron-containing material (calculated as B2O3), is the amount of boron-containing material in the hardened body (calculated as B2O3 in kg / m³). 3 = Unit weight of slag (kg / m³) 3 The mass ratio (mass%) of B2O3 converted from the amount of boron-containing substances adhered to it (%) / 100 is set to 0.5 kg / m³. 3 Above and 4.0 kg / m 3 In the following examples 81 to 101 of the present invention, the compressive strength is 20 N / mm². 2 In conclusion, even after being immersed in water at 80°C for 45 days, the hardened body remained intact.

[0085] On the other hand, in Comparative Examples 45-51, where the boron-containing material adhering to the slag surface was calculated as 0.05% by mass of the slag (based on B2O3 conversion), the amount of boron-containing material in the hardened body, calculated based on the product of the unit amount of slag and the mass ratio of the adhering boron-containing material converted to B2O3, did not reach 0.5 kg / m³. 3 In the expansion determination, a crack was confirmed after 45 days, indicating that the free MgO had expanded.

[0086] Table 6 shows the fit table of the test specimens made using slag B, as well as the results of the compressive strength and expansion determination.

[0087] [Table 6]

[0088]

[0089] It was confirmed that the unit weight of alumina cement was set at 75 kg / m³. 3 Above and 200kg / m 3 The following definition assumes that the boron-containing material adhering to the slag surface, converted to B2O3, accounts for at least 0.10% of the slag by mass, and that the unit amount of boron-containing material converted to B2O3 in the hardened body, calculated based on the product of the unit amount of slag and the mass ratio of the adhering boron-containing material converted to B2O3, is 0.5 kg / m³. 3 Above and 4.0 kg / m 3 In the following examples 102 to 122 of the present invention, the compressive strength is 20 N / mm². 2 Furthermore, even after being immersed in water at 80°C for 45 days, the hardened body remained intact.

[0090] On the other hand, in Comparative Examples 52-58, where the boron-containing material adhering to the slag surface was calculated as 0.05% by mass of the slag (based on B2O3 conversion), the amount of boron-containing material in the hardened body, calculated based on the product of the unit amount of slag and the mass ratio of the adhering boron-containing material converted to B2O3, did not reach 0.5 kg / m³. 3 In the expansion determination, a crack was confirmed after 45 days, indicating that the free MgO had expanded.

[0091] The fit table of the test specimens made using slag C, as well as the results of the compressive strength and expansion determination, are shown in Table 7.

[0092] [Table 7]

[0093]

[0094] It was confirmed that the unit weight of alumina cement was set at 75 kg / m³. 3 Above and 200kg / m 3 The following definition assumes that the boron-containing material adhering to the slag surface, converted to B2O3, accounts for at least 0.10% of the slag by mass, and that the unit amount of boron-containing material converted to B2O3 in the hardened body, calculated based on the product of the unit amount of slag and the mass ratio of the adhering boron-containing material converted to B2O3, is 0.5 kg / m³. 3 Above and 4.0 kg / m 3 In the following examples 123 to 131 of the present invention, the compressive strength is 20 N / mm². 2 In conclusion, even after being immersed in water at 80°C for 45 days, the hardened body remained intact.

[0095] On the other hand, although the boron-containing material adhering to the slag surface accounts for more than 0.10% by mass of the slag when converted to B2O3, the amount of boron-containing material in the hardened body, calculated based on the product of the unit amount of slag and the mass ratio of the adhering boron-containing material converted to B2O3, exceeds 4.0 kg / m³. 3 In comparative examples 59-61, the test specimens did not solidify. Furthermore, the unit quantity of slag C was set at 2379 kg / m³. 3 Comparative Example 62 had insufficient paste content, resulting in low compressive strength of the hardened body, less than 20 N / mm². 2 .

Claims

1. A hardened body utilizing slag containing free MgO, In the hardened body, the slag containing free MgO has a unit amount of 300 kg / m³. 3 Above and 2000 kg / m 3 The following is the unit weight of alumina cement: 75 kg / m³ 3 Above and 200kg / m 3 The following unit weight of blast furnace slag powder is 330 kg / m³. 3 Above and 530kg / m 3 The following calculations use B2O3 as the unit amount for boron-containing substances, which is 0.5 kg / m³. 3 Above and 4.0 kg / m 3 the following.

2. A method for manufacturing a hardened body using slag containing free MgO, wherein the method utilizes slag containing free MgO as a material to manufacture the hardened body, the method comprising: The unit quantity of slag containing free MgO is set at 300 kg / m³. 3 Above and 2000 kg / m 3 The unit weight of alumina cement is set at 75 kg / m³. 3 Above and 200kg / m 3 Hereinafter, the unit quantity of blast furnace slag powder is set at 330 kg / m³. 3 Above and 530kg / m 3 In the following calculations, the unit amount of boron-containing substances is set to 0.5 kg / m³ using B₂O₃ as the conversion factor. 3 Above and 4.0 kg / m 3 The following mixture is formed. Water is added to the mixture, and the mixture is kneaded. Then, the kneaded mixture is allowed to solidify.

3. A method for manufacturing a hardened body using slag containing free MgO, wherein the method utilizes slag containing free MgO as a material to manufacture the hardened body, the method comprising: Slag containing free MgO is impregnated in a solution containing dissolved boron, or a solution containing dissolved boron is sprayed onto slag containing free MgO, so that boron-containing substances, calculated as B2O3, at least 0.10% by mass of the slag, are pre-adhered to the surface of the slag containing free MgO. The unit quantity of the slag containing free MgO pre-attached with boron-containing substances is set at 300 kg / m³. 3 Above and 2000 kg / m 3 The following is an example of setting the amount of boron-containing material adhering to the surface of the slag to 0.5 kg / m³ (converted to B₂O₃). 3 Above and 4.0 kg / m 3 The unit weight of alumina cement is set at 75 kg / m³. 3 Above and 200kg / m 3 Hereinafter, the unit quantity of blast furnace slag powder is set at 330 kg / m³. 3 Above and 530kg / m 3 The following mixture is formed. Water is added to the mixture, and the mixture is kneaded. Then, the kneaded mixture is allowed to solidify.

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