Hydraulic composition, hardened body, and production method of hardened body

Abstract

To provide a hydraulic composition containing blast furnace slag powder that can reduce blue coloration immediately after curing when made into a hardened body.SOLUTION: The hydraulic composition comprises a hydraulic material and a hardening accelerator, wherein the hydraulic material comprises blast furnace slag powder, and the hardening accelerator comprises an inorganic peroxide.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hydraulic composition, a hardened product, and a method for producing the hardened product. [Background technology]

[0002] For example, Patent Document 1 discloses a method for manufacturing a concrete block, which comprises the steps of pouring a concrete material containing a binder and aggregate, wherein the binder contains 30% by weight or more of ground granulated blast furnace slag, to form a concrete block, applying a design to the surface of the concrete block, and oxidizing the designed surface of the concrete block. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-91207 Summary of the Invention [Problem to be solved by the invention]

[0004] Hydraulic compositions using blast furnace slag powder as a part of the hydraulic material and their hardened products are known. However, it is known that hardened products of hydraulic compositions using blast furnace slag powder develop a blue color immediately after curing.

[0005] Although the blue color of such a hardened product fades over time, it may take several months for the color to fade. Furthermore, since hardened products are often stored in stacks, the blue color may not fade even after several months on surfaces that are less exposed to the air. For this reason, when concrete blocks or the like are manufactured as hardened products of hydraulic compositions, they must wait until the blue color has sufficiently faded before shipping, which significantly hinders the inspection and shipping of concrete blocks. Therefore, in the past, treatments such as those for fading the blue color of hardened products have been performed.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hydraulic composition containing blast furnace slag powder that can reduce the blue color that occurs immediately after curing when made into a hardened body. [Means for solving the problem]

[0007] The hydraulic composition of the present disclosure includes a hydraulic material and a hardening accelerator, The hydraulic material includes blast furnace slag powder, The curing accelerator includes an inorganic peroxide. [Effects of the Invention]

[0008] The present invention can provide a hydraulic composition containing blast furnace slag powder that can reduce the blue color that appears immediately after curing when made into a hardened body. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and substitutions can be made to the following embodiments without departing from the scope of the present invention. [Hydraulic composition] The hydraulic composition of this embodiment includes a hydraulic material and a hardening accelerator. The hydraulic material includes blast furnace slag powder. The hardening accelerator includes an inorganic peroxide.

[0010] In this specification, hydraulic composition refers to a composition that hardens through a chemical reaction when mixed with water. The hydraulic composition may be a mixture of solid powders or the like that does not contain water, and may also contain water as described below. When it is necessary to distinguish between hydraulic compositions that do not contain water and those that contain water, the hydraulic composition that does not contain water may be referred to as hydraulic powder. Furthermore, the hydraulic composition that contains water may be referred to as a water-containing hydraulic composition, and when the water content is particularly high and the fluidity is high, it may be referred to as a hydraulic slurry. (1) Components contained in hydraulic compositions The components contained in the hydraulic composition of this embodiment will be described below. (1-1) Hydraulic material The hydraulic composition of this embodiment can contain a hydraulic material.

[0011] The hydraulic material means a material that hardens when water is added or when an alkaline stimulus or the like is further added.

[0012] The hydraulic material may include blast furnace slag powder.

[0013] Blast furnace slag powder is a by-product obtained during the production of pig iron in a blast furnace. It is ground slag obtained by the reaction of non-iron components contained in iron ore, limestone as an auxiliary material, and ash from coke in the blast furnace used to produce pig iron.

[0014] Blast furnace slag powder has latent hydraulic properties, which means that it hardens when exposed to alkaline stimulation. Since blast furnace slag powder is a by-product of steelmaking, the carbon dioxide emissions during its production are counted as part of the steelmaking process. Therefore, the hydraulic composition of this embodiment containing blast furnace slag powder can reduce carbon dioxide emissions and can be said to be a material with a low environmental impact.

[0015] Although the blast furnace slag powder is not particularly limited, it preferably has a high Blaine value in order to increase the initial strength of the hardened hydraulic composition, for example, 3000 Blaine or more is preferable, and 4000 Blaine or more is more preferable.

[0016] There is no particular upper limit to the Blaine value of the blast furnace slag powder, but a Blaine value of 8000 or less is preferable because a high Blaine value tends to make it difficult to handle, such as by adhering to the inside of a storage silo.

[0017] Therefore, for example, a material with a Blaine value of 3000 or more and 8000 or less can be used as the blast furnace slag powder, and it may also be a material with a Blaine value of 4000 or more and 8000 or less. When the Blaine value is within the above range, the blast furnace slag powder becomes a fine powder with a small particle size, and therefore the blast furnace slag powder may be referred to as ground blast furnace slag powder.

[0018] The Blaine value of the above-mentioned blast furnace slag powder refers to the Blaine value that is added when indicating the type (quality) of blast furnace slag powder, such as blast furnace slag powder 3000, in the standard for blast furnace slag powder for concrete, JIS A 6206 (2013).

[0019] In the above JIS standard, for blast furnace slag powder 3000 (Blaine value 3000), the specific Blaine specific surface area is 2750 cm 2 / g or more 3500cm 2 / g or less.

[0020] In the case of blast furnace slag powder 4000 (Blaine value 4000), the specific Blaine specific surface area is 3500 cm 2 / g or more 5000cm 2 / g or less.

[0021] In the case of blast furnace slag powder 6000 (Blaine value 6000), the specific Blaine specific surface area is 5000 cm 2 / g or more 7000cm 2 / g or less.

[0022] In the case of blast furnace slag powder 8000 (Blaine value 8000), the specific Blaine specific surface area is 7000 cm 2 / g or more 10000cm 2 / g or less.

[0023] Therefore, blast furnace slag powder with a Blaine specific surface area of ​​3000 or more and 8000 or less is 2750 cm 2 / g or more 10000cm 2 / g. In addition, blast furnace slag powder with a Blaine specific surface area of ​​4000 or more and 8000 or less means that the Blaine specific surface area is 3500 cm 2 / g or more 10000cm 2 / g.

[0024] The specific Blaine specific surface area can be evaluated according to JIS R 5201 (2015). The Blaine specific surface area in this specification means the specific surface area evaluated using a Blaine air permeation device as described in JIS R 5201 (2015).

[0025] The hydraulic material of the hydraulic composition of this embodiment may be composed of blast furnace slag powder alone, or may further contain other components.

[0026] The hydraulic composition of this embodiment may contain fly ash or limestone powder as a hydraulic material in addition to blast furnace slag powder. When the hydraulic composition of this embodiment contains a component other than blast furnace slag powder as a hydraulic material, the content thereof is preferably 0 to 30 parts by mass per 100 parts by mass of blast furnace slag powder. When the hydraulic composition of this embodiment contains multiple types of components other than blast furnace slag powder as hydraulic materials, the total content thereof preferably satisfies the above range.

[0027] The blending ratio of the hydraulic material in the hydraulic composition of this embodiment is not particularly limited, and can be selected depending on the strength required for the hydraulic composition of this embodiment.

[0028] The unit hydraulic material-hardening accelerator amount, which is the total unit amount of the hydraulic material and the hardening accelerator described later contained in the hydraulic composition of this embodiment, is 200 kg / m 3 More than 800kg / m 3 may be less than 250 kg / m 3 More than 800kg / m 3 It may be the following:

[0029] For example, the unit amount of hydraulic material-hardening accelerator is 200 kg / m3 More than 600kg / m 3 May be less than 200 kg / m 3 More than 550kg / m 3 The unit amount of hydraulic material-hardening accelerator is 200 kg / m 3 More than 600kg / m 3 By satisfying the following conditions, it is possible to at least satisfy the compressive strength classification A (08) for basic blocks of JIS A 5406 (2023).

[0030] In particular, when high strength is required for the hardened product of the hydraulic composition of this embodiment, the unit hydraulic material-hardening accelerator amount is 550 kg / m 3 More than 800kg / m 3 It may be the following:

[0031] The unit amount means the mass of the target material contained in a unit volume of a kneaded product of a hydraulic composition containing water, which is prepared in the process of producing a hardened body, for example, in the kneading step described below. Therefore, the unit amount of hydraulic material-hardening accelerator means the total mass of the hydraulic material and hardening accelerator contained in a unit volume of a kneaded product of a hydraulic composition containing water. (1-2) Curing accelerator (1-2-1) About hardening accelerators Blast furnace slag powder has latent hydraulic properties, which means that it hardens when exposed to an alkaline stimulus. The hardening accelerator becomes a material that imparts an alkaline stimulus to the blast furnace slag powder when mixed with water. Therefore, the hardening accelerator becomes a material that can impart an alkaline stimulus to the blast furnace slag powder when mixed with water. (Inorganic peroxide) The more the content of blast furnace slag powder in the hydraulic composition increases, and the more accelerated curing using steam is performed after molding the hydraulic composition, the more likely the set product of the hydraulic composition will have a strong blue color immediately after curing. This is thought to be because the sulfur component contained in the blast furnace slag powder forms sulfur salts, which then develop a color, resulting in the blue color.

[0032] Although the blue color of such a hardened product fades over time, it may take several months for the color to fade. Furthermore, since hardened products are often stored in stacks, the blue color may not fade even after several months on surfaces that are less exposed to the outside air. For this reason, when concrete blocks or the like are manufactured as hardened products of hydraulic compositions, they must be shipped until the blue color has sufficiently faded, which causes significant problems in the inspection and shipping of concrete blocks.

[0033] Therefore, the inventors of the present invention conducted research and found that when a curing accelerator contains an inorganic peroxide, the blue color of the cured product can be reduced. The curing accelerator may be composed only of an inorganic peroxide, or may contain an inorganic peroxide and further other components, as described below.

[0034] The mechanism by which the inclusion of an inorganic peroxide in the hardening accelerator reduces the blue color of the hardened body immediately after curing is presumed to be as follows.

[0035] When inorganic peroxides react with water, they produce hydroxide salts and hydrogen peroxide.

[0036] When the inorganic peroxide is calcium peroxide, calcium peroxide reacts with water according to the chemical formula shown in the following formula (1) to produce calcium hydroxide and hydrogen peroxide.

[0037] CaO2+2H2O→Ca(OH)2+H2O2··(1) Since hydrogen peroxide functions as an oxidizing agent, it is thought that when the hydraulic composition contains inorganic peroxide, the sulfur components contained in the blast furnace slag powder are oxidized, thereby reducing the blue color of the hardened hydraulic composition immediately after curing.

[0038] As described above, when inorganic peroxides react with water, they produce hydroxide salts in addition to hydrogen peroxide. The hydroxide salts dissolve in water and exhibit alkaline properties, which provide alkaline stimulation to the blast furnace slag powder and also function as a hardening accelerator.

[0039] The inorganic peroxide is not particularly limited, but is preferably an inorganic peroxide containing one or more elements selected from alkali metal elements and alkaline earth metal elements. The hydraulic composition of this embodiment may also contain multiple types of inorganic peroxides containing different elements.

[0040] In this specification, alkali metal elements include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

[0041] In this specification, alkaline earth metal elements refer to alkaline earth metal elements in a broad sense, such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

[0042] As the inorganic peroxide, it is preferable to use one or more selected from lithium peroxide (Li2O2), sodium peroxide (Na2O2), potassium peroxide (K2O2), magnesium peroxide (MgO2), calcium peroxide (CaO2), and barium peroxide (BaO2). In particular, because of low cost and excellent handling properties, it is preferable that the inorganic peroxide contains one or more selected from calcium peroxide and magnesium peroxide, and the inorganic peroxide may consist of only one or more selected from calcium peroxide and magnesium peroxide.

[0043] In particular, the inorganic peroxide preferably contains calcium peroxide because of its low cost and easy availability, and the inorganic peroxide may consist solely of calcium peroxide.

[0044] The inorganic peroxide may be used as a powder or formed into granules (pellets). By using the inorganic peroxide as a powder, the dispersibility of the inorganic peroxide can be improved when preparing the hydraulic composition. By forming the inorganic peroxide into a molded body such as granules, the workability of operations such as measuring can be improved.

[0045] To improve handleability, inorganic peroxides may be mixed with other bulking agents to form a mixture. When mixed with other bulking agents to form a mixture, the concentration of the inorganic peroxide contained in the mixture is not particularly limited, but can be, for example, 10% by mass or more and 35% by mass or less. By setting the concentration of the inorganic peroxide in the mixture to 10% by mass or more, the concentration of the inorganic peroxide in the mixture can be sufficiently high, allowing for a reduction in the amount of the mixture added when preparing a hydraulic composition. Furthermore, by setting the concentration of the inorganic peroxide in the mixture to 35% by mass or less, the reactivity of the inorganic peroxide in the mixture can be adjusted and stabilized, thereby improving handleability. When a mixture contains multiple types of inorganic peroxides, it is preferable that the total concentration of the inorganic peroxides satisfy the above range. Furthermore, the mixture may be used as a powder as described above, or may be used as a molded product such as granules. (Alkaline stimulant) The hardening accelerator may further include an alkaline stimulant.

[0046] As the alkaline stimulant, any material other than inorganic peroxides that can impart alkaline stimuli to hydraulic materials when mixed with water can be used.

[0047] The alkaline irritant may preferably be one or more selected from hydroxides and carbonates, and preferably contains one or more elements selected from alkali metal elements and alkaline earth metal elements.

[0048] Therefore, the alkali activator may contain one or more elements selected from alkali metal elements and alkaline earth metal elements, and may be one or more salts selected from hydroxides and carbonates. Since the alkali metal elements and alkaline earth metal elements have already been explained, their explanation will be omitted. The hydraulic composition of this embodiment may also contain multiple types of alkali activators containing different elements and salts.

[0049] As the alkaline stimulant, for example, one or more selected from calcium hydroxide (Ca(OH)2), sodium hydroxide (NaOH), potassium hydroxide (KOH), potassium carbonate (K2CO3), and sodium carbonate (Na2CO3) can be more preferably used.

[0050] From the viewpoint of increasing the strength of the set product of the hydraulic composition of this embodiment, the alkaline activator is more preferably one or more selected from sodium carbonate (soda ash) and calcium hydroxide.

[0051] The curing accelerator may be composed of only inorganic peroxide and may not contain an alkaline stimulant, however, since alkaline stimulants such as sodium carbonate are less expensive and more readily available than inorganic peroxides, it is preferred that the curing accelerator be a mixture of inorganic peroxide and alkaline stimulant.

[0052] However, when the ratio of the alkali stimulant contained in the hardening accelerator is high, the blue color of the cured body of the hydraulic composition may become relatively stronger compared to when the ratio of the alkali stimulant contained in the hardening accelerator is low. Also, when the ratio of the alkali stimulant contained in the hardening accelerator is high, efflorescence, which is a white precipitate, is more likely to occur on the surface of the molded body or the hardened body compared to when the ratio of the alkali stimulant contained in the hardening accelerator is low.

[0053] Efflorescence in concrete, which is a hardened product of ordinary cement, is formed when alkaline lye contained in the cement components precipitates on the surface of the concrete, etc. Therefore, the main component of efflorescence in ordinary concrete is calcium carbonate (CaCO3), which precipitates when calcium oxide (CaO), the main component of cement, reacts with water and carbon dioxide gas.

[0054] In the course of the inventors' research into hydraulic compositions, they found that when hydraulic compositions were prepared using sodium carbonate as an alkaline stimulant without adding inorganic peroxides or cement components as hardening accelerators, efflorescence sometimes precipitated on the surface of the molded or hardened concrete. That is, while the efflorescence in ordinary concrete is mainly composed of calcium carbonate, white precipitates were sometimes observed even though no calcium component was added.

[0055] Therefore, a qualitative analysis of the elements contained in the precipitated efflorescence was performed using an X-ray microanalyzer, and the main elements were found to be oxygen, sodium, sulfur, and carbon. This indicated that the observed efflorescence contained sodium carbonate, which was added as an alkaline irritant, as its main component. It was also confirmed that the amount of efflorescence generated could be reduced by adding inorganic peroxide as a hardening accelerator in addition to the alkaline irritant.

[0056] As described above, the curing accelerator contains an inorganic peroxide, which can reduce the occurrence of efflorescence in molded products and cured products. Furthermore, increasing the proportion of inorganic peroxide in the curing accelerator can particularly reduce the occurrence of efflorescence. Therefore, the mixing ratio of the inorganic peroxide and the alkaline irritant in the curing accelerator can be selected depending on the degree of efflorescence reduction required for the cured product, the degree of blue color, etc. For example, the proportion of the inorganic peroxide in the curing accelerator, based on the total amount of the inorganic peroxide and the alkaline irritant, may be 1% by mass or more and 100% by mass or less, 2% by mass or more and 80% by mass or less, 5% by mass or more and 50% by mass or less, or 5% by mass or more and 30% by mass or less.

[0057] The hydraulic composition of this embodiment preferably does not contain various cements that have conventionally been used as alkaline activators in hydraulic compositions using blast furnace slag powder, etc. Although cement may also function as a hydraulic material, it is preferable that the hydraulic composition of this embodiment does not contain various cements regardless of their function.

[0058] In the manufacturing process of cement, limestone (CaCO3) is burned at high temperatures and decarbonated to produce calcium oxide (CaO), which is the main component. Therefore, a large amount of carbon dioxide is emitted during the manufacturing process of cement, and the hydraulic composition of this embodiment does not contain various cements, so that the amount of carbon dioxide emitted during the manufacturing process can be reduced, making it a material with a low environmental impact.

[0059] The fact that the hydraulic composition of this embodiment does not contain various cements can also be rephrased as, for example, not containing ground clinker.

[0060] Here, the hydraulic composition of this embodiment does not contain various cements, i.e., does not contain ground clinker, means that they are not intentionally added, and does not exclude the possibility of them being mixed in as inevitable impurities during the manufacturing process, etc. In the hydraulic composition of this embodiment, the content of ground clinker can be set to 1 mass % or less, taking into account the mixing in of inevitable impurities, etc. (1-2-2) About the content of hardening accelerator The content of the hardening accelerator in the hydraulic composition of this embodiment is not particularly limited and can be selected depending on the strength required of the hydraulic composition, etc. The hydraulic composition of this embodiment preferably contains 3 to 25 parts by mass, more preferably 3 to 20 parts by mass, of the hardening accelerator per 100 parts by mass of the hydraulic material. The hydraulic material may be composed only of blast furnace slag powder, or may contain fly ash or limestone in addition to the blast furnace slag powder.

[0061] The hydraulic composition of this embodiment contains 3 parts by mass or more of a hardening accelerator per 100 parts by mass of hydraulic material, thereby increasing the strength of the set body. Although the strength of the set body also increases by increasing the ratio of the hardening accelerator to the hydraulic material, the degree of increase in the strength of the set body saturates at a ratio of about 25 parts by mass of hardening accelerator per 100 parts by mass of hydraulic material. Therefore, the hydraulic composition of this embodiment preferably contains 25 parts by mass or less of a hardening accelerator per 100 parts by mass of hydraulic material. (1-3) Other additives The hydraulic composition of this embodiment may further contain other additive components. (1-3-1)Water The hydraulic composition of this embodiment may further contain water.

[0062] The amount of water contained in the hydraulic composition of this embodiment is not particularly limited, and can be selected depending on the fluidity required for the hydraulic composition, the strength required for the set product, and the like.

[0063] The hydraulic composition of this embodiment can be molded using a mold, for example, and used as a concrete block or the like. By forming a hard-mix hydraulic composition with zero slump, it becomes possible to immediately demold the composition after filling it into a mold. That is, by forming a hydraulic composition with zero slump, it becomes possible to maintain the molded shape even after immediate demolding, and the time left after filling it into a mold can be shortened, thereby increasing productivity.

[0064] Therefore, the hydraulic composition of this embodiment has a unit water amount of 130 L / m 3 The hydraulic composition of this embodiment may have a unit water amount of 130 L / m 3 By setting the temperature below, zero slump can be achieved, and productivity of hardened products such as concrete blocks can be improved.

[0065] The lower limit of the unit water content of the hydraulic composition of this embodiment is not particularly limited, but is, for example, 60 L / m 3 It can do more than that.

[0066] For example, in order to perform pour molding, the unit water amount of the hydraulic composition of this embodiment is set to 130 L / m 3 In this case, the upper limit of the unit water content of the hydraulic composition of this embodiment is not particularly limited, but it can be, for example, 500 L / m 3 Therefore, the hydraulic composition of this embodiment may have a unit water amount of 130 L / m or less. 3 More than 500L / m 3 The following may also be used.

[0067] The unit water content means the amount of water per unit volume of the kneaded product of the water-containing hydraulic composition prepared in the process of producing the hardened body, for example, in the kneading step described below. The density of water is 1 g / cm 3 So, L / m 3 is kg / m 3 It may also be possible to use the following. (1-3-2) Aggregate The hydraulic composition of this embodiment may also contain aggregate.

[0068] The aggregate may be one or more selected from sand, gravel, crushed sand, crushed stone, various slags, etc. The sand may be natural aggregate such as river sand, and the crushed stone may be crushed rock or boulders.

[0069] (1-3-3) Other additives In addition to the above materials, the hydraulic composition of this embodiment may also contain admixtures such as air-entraining agents and water-reducing agents, and colorants such as chromium oxide, iron oxide, red iron oxide, and titanium oxide. [Cured body] The hardened product of this embodiment can be a hardened product of the hydraulic composition according to one aspect of the present disclosure.

[0070] The hydraulic composition described above contains a hydraulic material and a hardening accelerator, the hydraulic material containing blast furnace slag powder, and the hardening accelerator containing an inorganic peroxide. Therefore, the hardened body of this embodiment can reduce the blue color and suppress the occurrence of efflorescence even immediately after curing.

[0071] Furthermore, the cured product of this embodiment can reduce carbon dioxide emissions during production, resulting in a cured product with low environmental impact.

[0072] The hardened product of this embodiment may be a molded product obtained by molding the hydraulic composition according to one aspect of the present disclosure into a predetermined shape. Examples of the hardened product of this embodiment include concrete blocks, and may be one or more types selected from, for example, concrete blocks for construction such as hollow blocks and formwork blocks, and concrete blocks for paving such as interlocking blocks. Although the term "concrete block" is used because of the use of commonly used trade names, the hydraulic composition according to one aspect of the present disclosure preferably does not contain cement, and therefore the concrete block, which is its hardened product, preferably also does not contain a cement component.

[0073] The hardened body of this embodiment can reduce the blue color on the surface immediately after curing, for example, within 7 days after the end of curing, or within 7 days after the end of a curing process such as an accelerated curing process. For example, compared with a case in which the hardening accelerator contained in the hydraulic composition used in the hardened body of this embodiment does not contain an inorganic peroxide and contains only an alkaline irritant, L * a * b * b in color space (JIS Z 8781-4(2013)) * The color can be compared between a set product using a hydraulic composition in which the inorganic peroxide is replaced with the same mass of an alkali irritant, for example. The color may also be compared between a set product using a hydraulic composition containing only an alkali irritant, but no inorganic peroxide as a hardening accelerator, and the same unit amounts of other components.

[0074] The hardened body of this embodiment can be, for example, L * a * b * b in color space * can also be greater than 0. [Method of manufacturing the hardened product] The method for producing a hardened body of this embodiment can include the following kneading step, molding step, and demolding step. Note that, since the method for producing a hardened body of this embodiment can produce a hardened body according to one aspect of the present disclosure, and a hydraulic composition can also be produced in the process, some of the matters already explained will not be explained again. Each step will be explained below. (1) Mixing process In the kneading step, a hydraulic material, a hardening accelerator, and water are kneaded to form a hydraulic composition. The hydraulic material may include blast furnace slag powder. The hardening accelerator may include inorganic peroxide.

[0075] In the kneading step, components that can be contained in the hydraulic composition can be kneaded. Each component has already been explained, so explanation will be omitted. Note that, since water is also added in the kneading step, a water-containing hydraulic composition, which is a hydraulic composition containing water, is obtained.

[0076] The unit water amount of the hydraulic composition obtained in the kneading step is not particularly limited, but is, for example, 130 L / m 3 The unit water volume may be 130 L / m or less. 3 By doing so, zero slump can be achieved and immediate demolding can be performed in the molding process, thereby increasing the productivity of concrete blocks, etc.

[0077] In addition, when pouring and molding, the unit water volume is 130L / m 3 More than 500L / m 3 The following may also be used. (2) Molding process In the molding step, the hydraulic composition can be filled into a mold to form a molded body.

[0078] The mold used in the molding step is not particularly limited, and can have a shape that matches the concrete block or the like to be manufactured. (3) Demolding process In the demolding step, the molded body can be demolded from the mold.

[0079] The timing of demolding is not particularly limited, but the molded body can be demolded at a timing depending on the fluidity of the hydraulic composition constituting the molded body, etc., so that the demolded molded body can maintain the desired shape.

[0080] For example, if the unit water content of the hydraulic composition obtained in the kneading step is sufficiently small, the demolding step can be carried out immediately after the molding step. That is, immediate demolding can be carried out. By enabling immediate demolding, productivity of the hardened body can be increased. (4) Other processes The method for producing a cured body according to the present embodiment may further include an optional step. (4-1)Curing process The method for producing a hardened body according to the present embodiment may also include a curing step of curing the molded body after the demolding step.

[0081] The conditions for the curing step are not particularly limited, but for example, steam curing can be performed using a steam curing facility in an environment of 40°C or higher.

[0082] The upper limit of the temperature during steam curing in the curing step is not particularly limited, but can be, for example, 65° C. or lower. The duration of steam curing is not particularly limited, but, for example, the heating time to reach the above temperature range may be 2 hours or more and 12 hours or less.

[0083] In the curing step, curing can also be performed using an autoclave, in which case curing can be performed by maintaining a temperature of 180°C to 190°C and a pressure of 10 to 11 atmospheres for approximately 3 to 5 hours. When curing using an autoclave, it is preferable to perform curing under isothermal and isobaric conditions in which the temperature and pressure are maintained after the above temperature and pressure are reached.

[0084] Accelerated curing of the compact can improve the initial strength of the hardened body even if the hydraulic material contains a large amount of blast furnace slag powder. Curing using an autoclave, in particular, can reduce the occurrence of efflorescence. [Example]

[0085] The present invention will be explained below by giving specific examples, but the present invention is not limited to these examples. (Evaluation method) (1) Compressive strength The compressive strength was evaluated using the compressive strength test method specified in Appendix B of JIS A 5406 (2023).

[0086] The measurements were carried out after the curing process. (2) Color evaluation After the curing step, at least one surface of the hardened body was immersed in water for 7 days, and then the color of the surface of the hardened body was measured using a colorimeter (manufactured by Minolta, model: CR-310). [Experimental Example 1] [Example 1-1] A hydraulic composition and a hardened product were produced according to the following procedure.

[0087] The raw materials were weighed to obtain the ratios shown in Table 1 and kneaded to prepare a hydraulic composition (kneading step). The blast furnace slag powder used was 4000 ground granulated blast furnace slag as specified in JIS A 6206 (2013), and the specific evaluation value of the Blaine specific surface area was 4720 cm. 2 In the other examples and comparative examples below, the same blast furnace slag powder is used as the blast furnace slag powder indicated as "Blast furnace slag powder 4000 Blaine" in the recipe.

[0088] Next, the obtained hydraulic composition was filled into a mold to form a molded body (molding step).

[0089] The molded body was demolded from the mold (demolding step). The demolding step was immediate demolding, which was carried out immediately after the molding step.

[0090] After the demolding process, the molded body was steam cured in an environment of 65°C. After the steam curing, it was further subjected to natural curing for 7 days (curing process). That is, the hardened body after 7 days of steam curing was evaluated as follows.

[0091] The cured product was evaluated as described above, and the evaluation results are shown in Table 2. [Comparative Example 1-1] A hydraulic composition was prepared (kneading step) by kneading the raw materials weighed to obtain the ratios shown in Table 1. In Comparative Example 1-1, calcium peroxide, which is an inorganic peroxide, was not added as a hardening accelerator, and calcium peroxide was replaced with soda ash, which is sodium carbonate.

[0092] Except for the above points, molded articles and cured articles were produced under the same conditions as in Example 1-1, and evaluations were carried out. The evaluation results are shown in Table 2. [Example 1-2] A hydraulic composition was prepared (kneading step) by kneading raw materials weighed to obtain the ratios shown in Table 1. In Example 1-2, a black pigment was further added so that the occurrence of efflorescence could be confirmed.

[0093] Except for the above points, molded articles and cured articles were produced under the same conditions as in Example 1-1, and evaluations were carried out. The evaluation results are shown in Table 2. [Comparative Example 1-2] A hydraulic composition was prepared (kneading step) by kneading the raw materials weighed to obtain the ratios shown in Table 1. In Comparative Example 1-2, calcium peroxide, which is an inorganic peroxide, was not added as a hardening accelerator, and calcium peroxide was replaced with soda ash.

[0094] Except for the above points, molded articles and cured articles were produced and evaluated under the same conditions as in Example 1-2. The evaluation results are shown in Table 2. [Examples 1-3 to 1-5] The raw materials were weighed so as to have the ratios shown in Table 1 and kneaded together to prepare hydraulic compositions (kneading step).

[0095] In Example 1-3, no alkaline stimulant was used as the hardening accelerator, and only calcium peroxide, an inorganic peroxide, was added. The unit amount of the hardening accelerator was set to the same value as in Example 1-1.

[0096] In Example 1-4, no alkaline stimulant was used as the hardening accelerator, and only calcium peroxide, an inorganic peroxide, was added. In this case, more inorganic peroxide was added than in Example 1-3 so that the unit amount of inorganic peroxide was the value shown in Table 1.

[0097] In Examples 1-5, no alkaline irritant was used as the hardening accelerator, and only calcium peroxide, an inorganic peroxide, was added. In this case, the calcium peroxide was mixed with a bulking agent to make the calcium peroxide concentration 35% by mass, which improved handling. By keeping the calcium peroxide at 35% by mass or less, it is no longer classified as a hazardous material under the Fire Service Act. The inorganic peroxide was added so that the unit amount mixed with the bulking agent was the value shown in Table 1.

[0098] Therefore, in Table 1, the unit amount of inorganic peroxide (calcium peroxide) is 110 kg / m 3 However, the unit amount of calcium peroxide excluding the bulking agent is 38.5 kg / m 3 becomes.

[0099] Except for the above points, molded articles and cured articles were produced under the same conditions as in Example 1-1, and evaluations were carried out. The evaluation results are shown in Table 2.

[0100] [Table 1]

[0101] [Table 2] According to the results shown in Table 2, the compressive strength was 16 N / mm in both Example 1-1 and Example 1-2. 2 It was confirmed that the specimens had high compressive strength.

[0102] For Examples 1-3, the compressive strength was 16 N / mm 2 Although the compressive strength was below 16 N / mm in Examples 1-4 and 1-5, in which the amount of inorganic peroxide added was increased,2 It was confirmed that it exceeds

[0103] According to the results shown in Table 2, in Examples 1-1 and 1-2 in which calcium peroxide was added as a hardening accelerator, the hardening rate was higher than that of the corresponding Comparative Examples 1-1 and 1-2. * It was confirmed that the value of b increased and the blue hue was reduced. * It was confirmed that the value was greater than 0.

[0104] For Example 1-3, the b * It was confirmed that the value of b increased and the blue hue was reduced. * It was confirmed that the value was greater than 0.

[0105] In Examples 1-4 and 1-5, in which the amount of inorganic peroxide added was further increased compared to Example 1-3, the * It was confirmed that the value of b increased and the blue hue was reduced. * It was confirmed that the value was greater than 0.

[0106] In addition, when Example 1-2 in which a black pigment was added was compared with Comparative Example 1-2, Comparative Example 1-2 had a higher L * It was confirmed that the occurrence of efflorescence was reduced in Example 1-2. Note that, since Examples 1-1, 1-3, 1-4, and 1-5, and Comparative Example 1, are not colored black, the L * The occurrence of efflorescence cannot be determined from brightness. [Experimental Example 2] In Experimental Example 2, the cases where magnesium peroxide was used as the inorganic peroxide and calcium hydroxide was used as the alkaline irritant were examined. [Example 2-1] A hydraulic composition and a hardened product were produced according to the following procedure.

[0107] The raw materials were weighed so as to obtain the ratios shown in Table 3 and kneaded to prepare hydraulic compositions (kneading step). The blast furnace slag powder used was ground granulated blast furnace slag 4000 as specified in JIS A 6206 (2013).

[0108] In this example, magnesium peroxide is used as the inorganic peroxide, and no alkaline irritant is added.

[0109] Next, the obtained hydraulic composition was filled into a mold to form a molded body (molding step).

[0110] The molded body was demolded from the mold (demolding step). The demolding step was immediate demolding, which was carried out immediately after the molding step.

[0111] After the demolding step, the green body was steam cured in an environment of 65° C. After the steam curing, natural curing was also carried out for an additional 7 days (curing step).

[0112] The cured product was evaluated as described above, and the evaluation results are shown in Table 4. [Example 2-2] A hydraulic composition was prepared (kneading step) by kneading raw materials weighed to obtain the ratios shown in Table 3. In Example 2-2, magnesium peroxide, which is an inorganic peroxide, was used in the unit amount shown in Table 3, and soda ash was added as an alkaline stimulant.

[0113] Except for the above points, molded articles and cured articles were produced under the same conditions as in Example 2-1, and evaluations were carried out. The evaluation results are shown in Table 4. [Example 2-3] The raw materials were weighed out so as to obtain the ratios shown in Table 3 and kneaded to prepare hydraulic compositions (kneading step). In Example 2-3, calcium peroxide, an inorganic peroxide, was used in the unit amounts shown in Table 3. In this case, the calcium peroxide was mixed with a bulking agent to make the calcium peroxide concentration 32 mass % and improve handleability. The inorganic peroxide was added so that the unit amount mixed with the bulking agent was the value shown in Table 3.

[0114] Therefore, in Table 3, the unit amount of calcium peroxide, which is an inorganic peroxide, is 20 kg / m 3 However, the unit amount of calcium peroxide excluding the bulking agent is 6.4 kg / m 3 becomes.

[0115] Calcium hydroxide is added instead of soda ash as an alkaline stimulant.

[0116] Except for the above points, molded articles and cured articles were produced under the same conditions as in Example 2-1, and evaluations were carried out. The evaluation results are shown in Table 4.

[0117] [Table 3]

[0118] [Table 4] According to Table 4, it was confirmed that the compressive strength of all of Examples 2-1, 2-2, and 2-3 at least met the low level of compressive strength category 08 of JIS A 5406 (2023) for concrete blocks for construction. In other words, it was confirmed that the hydraulic composition according to one embodiment of the present disclosure has hardening properties and sufficient compressive strength, regardless of the type of inorganic peroxide or alkaline activator. In particular, in Examples 2-2 and 2-3, in which an alkaline activator was added, the compressive strength was 16 N / mm 2 It was confirmed that the specimens had high compressive strength.

[0119] According to the results shown in Table 4, in Examples 2-1 and 2-2 in which magnesium peroxide was added as a hardening accelerator, and in Example 2-3 in which calcium hydroxide was used as an alkaline stimulant, *It was confirmed that the value was greater than 0. In other words, it was confirmed that the blue tint could be reduced in all of the cured bodies of Examples 2-1 to 2-3, regardless of the type of inorganic peroxide or alkaline irritant. [Experimental Example 3] In Experimental Example 3, the influence of the Blaine specific surface area of ​​blast furnace slag powder was investigated. [Example 3-1] A hydraulic composition and a hardened product were produced according to the following procedure.

[0120] The raw materials were weighed to obtain the ratios shown in Table 5 and kneaded to prepare hydraulic compositions (kneading step). The blast furnace slag powder used was 6000 ground granulated blast furnace slag as specified in JIS A 6206 (2013), and the specific evaluation value of the Blaine specific surface area was 5840 cm. 2 / g.

[0121] In Example 3-1, calcium peroxide, an inorganic peroxide, was used in the unit amount shown in Table 5. In this case, the calcium peroxide was mixed with a bulking agent to make the calcium peroxide concentration 32 mass % to improve handling. The inorganic peroxide mixed with the bulking agent was added so that the unit amount was the value shown in Table 5.

[0122] Therefore, in Table 5, the unit amount of calcium peroxide, which is an inorganic peroxide, is 110 kg / m 3 However, the unit amount of calcium peroxide excluding the bulking agent is 35.2 kg / m 3 becomes.

[0123] Next, the obtained hydraulic composition was filled into a mold to form a molded body (molding step).

[0124] The molded body was demolded from the mold (demolding step). The demolding step was immediate demolding, which was carried out immediately after the molding step.

[0125] After the demolding step, the green body was steam cured in an environment of 65° C. After the steam curing, natural curing was also carried out for an additional 7 days (curing step).

[0126] The cured product was evaluated as described above, and the evaluation results are shown in Table 6. [Example 3-2] The blast furnace slag powder used was 8000 granulated blast furnace slag as specified in JIS A 6206 (2013), and the specific evaluation value of the Blaine specific surface area was 8150 cm 2 / g.

[0127] Except for the above points, molded articles and cured articles were produced under the same conditions as in Example 3-1, and evaluations were carried out. The evaluation results are shown in Table 6.

[0128] [Table 5]

[0129] [Table 6] According to the results shown in Table 6, the compressive strength was 16 N / mm in both Example 3-1 and Example 3-2. 2 It was confirmed that the blast furnace slag powder had high compressive strength regardless of its Blaine value.

[0130] According to the results shown in Table 6, regardless of the Blaine specific surface area of ​​the blast furnace slag powder, b * It was confirmed that the value was greater than 0. That is, it was confirmed that the blue tint was reduced in both the cured products of Example 3-1 and Example 3-2. [Experimental Example 4] In Experimental Example 4, the production of a hardened body by casting was investigated. [Example 4-1] A hydraulic composition and a hardened product were produced according to the following procedure.

[0131] The raw materials were weighed so as to obtain the ratios shown in Table 7 and kneaded to prepare hydraulic compositions (kneading step). The blast furnace slag powder used was ground granulated blast furnace slag 4000 as specified in JIS A 6206 (2013).

[0132] In Example 4-1, calcium peroxide, an inorganic peroxide, was used in the unit amount shown in Table 7. In this case, the calcium peroxide was mixed with a bulking agent to make the calcium peroxide concentration 32 mass % to improve handling. The inorganic peroxide mixed with the bulking agent was added so that the unit amount was the value shown in Table 7.

[0133] Therefore, in Table 7, the unit amount of calcium peroxide, which is an inorganic peroxide, is 34 kg / m 3 However, the unit amount of calcium peroxide excluding the bulking agent is 10.88 kg / m 3 becomes.

[0134] To prevent the unit water volume from becoming excessively large, a water-reducing agent, a chemical admixture for concrete, is used, as shown in Table 7.

[0135] Next, the obtained hydraulic composition was poured into a mold to form a molded body (molding step).

[0136] The molded body was demolded from the mold (demolding step). The demolding step was carried out after it was confirmed that the molded body had sufficiently hardened after the molding step.

[0137] After the demolding process, underwater curing was carried out (curing process).

[0138] The cured product was evaluated as described above, and the evaluation results are shown in Table 8.

[0139] Four types of test specimens (hardened specimens) were prepared with different curing days (material ages): 3 days (3d), 7 days (7d), 14 days (14d), and 28 days (28d), and compressive strength tests were conducted. Color evaluation using a colorimeter was conducted on test specimens that had been cured for 3 days. [Example 4-2] The unit amount of calcium peroxide, an inorganic peroxide, was changed, and soda ash, an alkaline irritant, was not added. In addition, ingredients other than calcium peroxide and soda ash were weighed and mixed to achieve the unit amounts shown in Table 7.

[0140] Except for the above points, molded articles and cured articles were produced under the same conditions as in Example 4-1, and then evaluated. The evaluation results are shown in Table 8.

[0141] [Table 7]

[0142] [Table 8] According to the results shown in Table 8, in both Example 4-1 and Example 4-2, the compressive strength was 16 N / mm 2 It was confirmed that the specimens had high compressive strength, exceeding the age of 100 days. In particular, the specimens with longer ages had higher compressive strength, demonstrating that the specimens had higher compressive strength than the other experimental examples.

[0143] According to the results shown in Table 8, in Examples 4-1 and 4-2, even though the test specimens were cured for three days, which is the period when the blue color is most likely to appear, * The value was greater than 0, and it was confirmed that the blue hue was reduced.

Claims

1. Contains a hydraulic material and a hardening accelerator, The hydraulic material includes blast furnace slag powder, The hydraulic composition, wherein the hardening accelerator comprises an inorganic peroxide.

2. The hydraulic composition according to claim 1 , wherein the hardening accelerator further comprises an alkaline activator.

3. 3. The hydraulic composition according to claim 1, wherein the inorganic peroxide comprises at least one selected from calcium peroxide and magnesium peroxide.

4. 3. The hydraulic composition according to claim 1, wherein the hardening accelerator is contained in an amount of 3 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the hydraulic material.

5. It further contains water, and the unit water volume is 130 L / m ３ The hydraulic composition according to claim 1 or 2, wherein:

6. A hardened product of the hydraulic composition according to claim 1 or 2.

7. a kneading step of kneading a hydraulic material, a hardening accelerator, and water to form a hydraulic composition; a molding step of filling the hydraulic composition into a mold to form a molded body; and a demolding step of demolding the molded body from the mold, The hydraulic material includes blast furnace slag powder, The method for producing a cured body, wherein the curing accelerator contains an inorganic peroxide.

8. The unit water amount of the hydraulic composition obtained in the kneading step is 130 L / m ３ The method for producing a cured body according to claim 7, wherein the cured body is:

9. 9. The method for producing a hardened body according to claim 7, further comprising, after the demolding step, a curing step of steam curing the molded body in an environment of 40°C or higher.

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