Cured product, composition for cured product, and method for blending cured product

Abstract

To provide a hardened concrete having higher performance than conventional concrete. [Solution] The composition contains water, a hydration-reactive material, a latent hydraulic material, a pozzolanic-reactive material, a hydroxide ion supplying material, an expansive material, fine aggregate, coarse aggregate, and a high-performance water-reducing agent. The hydration-reactive material, latent hydraulic material, and pozzolanic-reactive material are prepared in terms of particle size or specific surface area so that the portion of the hardened body excluding the fine and coarse aggregate is filled with hardening reaction products generated and precipitated on the particle surfaces during the hardening reaction of the material particles, resulting in densification. This reduces the penetration of aqueous solutions into the hardened body and improves the durability of structures using the hardened body. This improves salt damage resistance.

Description

[Technical Field]

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

[0002] Concrete is a hardened substance made by mixing one or a combination of hydration-reactive materials such as cement, materials with latent hydraulic properties (hereinafter referred to as "latent hydraulic materials"), and materials with pozzolanic reactivity (hereinafter referred to as "pozzolanic reactive materials"), and hardening them through a hydration reaction, latent hydraulic reaction, or pozzolanic reaction, or a combination of these reactions.

[0003] Conventionally, in order to improve chemical resistance, improve resistance to sulfuric acid, and inhibit the penetration of hydrogen sulfide and carbon dioxide and the intrusion of seawater, there have been products in which ordinary Portland cement is mixed with industrial by-products such as ground granulated blast furnace slag or fly ash, or in which the amount of ordinary Portland cement is reduced.

[0004] Furthermore, Patent Document 1 describes acid-resistant concrete, which is a hardened body obtained by adding fine and coarse aggregate to a mixture of ground granulated blast furnace slag, fly ash, silica fume, and sewage sludge incineration ash instead of ordinary Portland cement, and then hardening the mixture. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Patent Publication No. 2019 / 172349 Summary of the Invention [Problem to be solved by the invention]

[0006] It was thought that by making a hardened body denser, which is manufactured from a single material or a mixture of multiple materials like the conventional concrete described in Patent Document 1, it would be possible to improve its resistance to sulfuric acid and chemicals, as well as its resistance to the penetration of carbon dioxide and seawater. For this reason, there was a technical need to establish a mixing method that would densify the hardened body by causing the materials to undergo a hardening reaction.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a method for compounding a cured product with higher performance by solving the above problems. [Means for solving the problem]

[0008] The hardened body of the present invention is characterized in that it is a mixture of water, a hydration-reactive material, a latent hydraulic material, a pozzolanic-reactive material, a hydroxide ion supplying material, an expansive material, a fine aggregate, a coarse aggregate, and a high-performance water-reducing agent, and the hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared in such a way that, in terms of particle size or specific surface area, the portion of the hardened body excluding the fine aggregate and coarse aggregate is filled with hardening reaction products that are generated and precipitated on the particle surfaces by the hardening reaction of the material particles, thereby densifying the hardened body. The hardened product of the present invention is characterized in that the hydration-reactive material includes any one or any combination of portland cement, blast furnace cement, fly ash cement, calcium hydroxide, and materials that harden by undergoing a hydration reaction; the latent hydraulic material includes any one or any combination of blast furnace slag fine powder, sewage sludge incineration ash, and materials that harden by undergoing a hydraulic reaction in an alkaline atmosphere; the pozzolanic-reactive material includes any one or any combination of fly ash, sewage sludge incineration ash, silica fume, fine volcanic glass powder for concrete, and materials that harden by undergoing a pozzolanic reaction in response to the stimulation of alkali; and the hydroxide ion supplying material includes any one or any combination of potassium hydroxide, potassium carbonate, and hydrated lime. The hardened body of the present invention is characterized in that the hardening reaction products that are produced and precipitated on the surfaces of the material particles block the expanded bottoms of the pores present in the portion excluding the fine aggregate and coarse aggregate, which is modeled as a cylindrical or conical shape, and are adjusted so as not to inhibit the movement of hardening reaction-required substances, which are present in the narrowed portion of the pores and are necessary for the hardening reaction of materials with small particle sizes or large specific surface areas, from the narrowed portion of the pores, and the reaction-required substances include gel water, hydroxide ions, silicate compounds, and magnesium oxide. The hardened body of the present invention is characterized in that it is a mixture of water, a hydration-reactive material, a latent hydraulic material, a pozzolanic-reactive material, a hydroxide ion supplying material, an expansive material, a fine aggregate, a coarse aggregate, and a high-performance water-reducing agent, and the hydroxide ion supplying material includes any one or any combination of potassium hydroxide, potassium carbonate, slaked lime, and hydroxide ion compound materials other than the hydroxide ion supplying material. The composition for a hardened body of the present invention is characterized in that it contains water, a hydration-reactive material, a latent hydraulic material, a pozzolanic-reactive material, a hydroxide ion supplying material, an expansive material, fine aggregate, coarse aggregate, and a high-performance water-reducing agent, and the hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared so that the particle sizes or specific surface areas of the hardened body, excluding the fine aggregate and coarse aggregate, are densified by a hardening reaction product that precipitates on the particle surfaces when the hardening reaction of the materials occurs. The method for blending a hardened body of the present invention is characterized in that water, a hydration-reactive material, a latent hydraulic material, a pozzolanic-reactive material, a hydroxide ion supplying material, an expansive material, a fine aggregate, a coarse aggregate, and a high-performance water-reducing agent are blended, and the hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared in such a way that, in terms of particle size or specific surface area, the portion of the hardened body excluding the fine aggregate and coarse aggregate is filled with hardening reaction products that are produced and precipitated on the particle surfaces by the hardening reaction of the material particles, thereby densifying the hardened body. The method for blending a hardened product of the present invention is characterized in that the hydration-reactive material includes any one or any combination of portland cement, blast furnace cement, fly ash cement, calcium hydroxide, and materials that harden by undergoing a hydration reaction; the latent hydraulic material includes any one or any combination of ground blast furnace slag, sewage sludge incineration ash, and materials that harden by undergoing a hydraulic reaction in an alkaline atmosphere; the pozzolanic-reactive material includes any one or any combination of fly ash, sewage sludge incineration ash, silica fume, finely powdered volcanic glass for concrete, and materials that harden by undergoing a pozzolanic reaction in response to the stimulation of alkali; and the hydroxide ion supplying material includes any one or any combination of potassium hydroxide, potassium carbonate, and hydrated lime. The method for blending a hardened body of the present invention is characterized in that the hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared so that the start of the hardening reaction of a material with a large particle size or a small specific surface area is delayed compared to a material with a small particle size or a large specific surface area. The method for blending a hardened body of the present invention is characterized in that a hardened reaction product produced by hardening the hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material fills voids present in the portion of the hardened body excluding fine aggregate and coarse aggregate, thereby densifying the portion, the hardened reaction product including calcium silicate, calcium hydroxide, calcium aluminosilicate hydrate, calcium silicate hydrate, hydrotalcite, ettringite, and monosulfate, and the voids include gel voids, capillary voids, micropores, mesopores, and macropores. The method for blending a hardened body of the present invention is characterized in that the hardening reaction products that are produced and precipitated on the surfaces of material particles block the expanded bottoms of pores present in the part of the hardened body that is modeled as a cylindrical or conical shape, excluding the fine aggregate and coarse aggregate, and are adjusted so as not to inhibit the movement of hardening reaction necessary substances that are present in the narrowed parts of the pores and are necessary for the hardening reaction of materials with small particle sizes or large specific surface areas present in the narrowed parts of the pores to the narrowed parts of the pores, and the hardening reaction necessary substances include gel water, hydroxide ions, silicate compounds, and magnesium oxide. The method for blending a hardened body of the present invention is characterized by blending the pozzolan-reactive material, which takes a long time to initiate the hardening reaction, with the latent hydraulic material, which initiates the hardening reaction quickly, and a hydration-reactive material, so that the hardening reaction begins from materials with small particle diameters or large specific surface areas to materials with large particle diameters or small specific surface areas; promoting the movement of the substances necessary for the hardening reaction toward the narrowed portions of the pores; promoting the hardening reaction of materials with small particle diameters or large specific surface areas that are present in and near the narrowed portions of the pores, and promoting the production and precipitation of the hardening reaction products on the surfaces of the material particles; and filling the pores, which are modeled as cylindrical or conical, present in the part of the hardened body excluding the fine aggregate and coarse aggregate, from the narrowed portion to the expanded portion with the hardening reaction products. [Effects of the Invention]

[0009] According to the present invention, a method for compounding hardened concrete can be provided in which voids present in the portion of the hardened concrete excluding the fine aggregate and coarse aggregate are filled with a hydration-reactive material and a hardening reaction product that precipitates and forms on the surfaces of the material particles as the latent hydraulic material and pozzolanic-reactive material harden, thereby densifying this portion. This results in a dense hardened concrete that is more effective at improving chemical resistance, sulfuric acid resistance, resistance to carbonation, and resistance to salt damage than conventional concrete. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a graph showing the experimental results of the reduction in pore volume due to hardening reaction products on the particle surfaces of IBPM concrete according to Example 1 of the present invention. [Figure 2] 10 is a graph showing experimental results regarding the reduction in pore volume due to hardening reaction products on the particle surfaces of OPC concrete according to a comparative example of the present invention. [Figure 3] 1 is a graph showing the experimental results of the reduction in pore volume due to hardening reaction products on the particle surfaces of FC concrete according to Example 1 of the present invention. [Figure 4]1 is a graph showing the relationship between the pore size and pore volume of pores in IBPM concrete in a salt damage resistance test according to Example 1 of the present invention. [Figure 5] 3 is a graph showing the change in concentration of chloride ions penetrating into the interior of IBPM concrete in a salt damage resistance test according to Example 1 of the present invention. [Figure 6] 1 is a graph showing the relationship between the pore size and pore volume of pores from OPC concrete in a salt damage resistance test according to a comparative example of the present invention. [Figure 7] 1 is a graph showing the change in concentration of chloride ions penetrating into the inside of OPC concrete in a salt damage resistance test according to a comparative example of the present invention. [Figure 8] 10 is a graph showing the relationship between water penetration depth and immersion time for IBPM concrete according to Example 2 of the present invention. [Figure 9] 10 is a graph showing the relationship between water penetration depth and immersion time for OPC concrete according to a comparative example of the present invention. [Figure 10] 10 is a photograph showing the state of water penetration depth measurement (30 MPa) according to Example 2 of the present invention. [Figure 11] 10 is a graph showing the calculation results of the water penetration rate coefficient according to Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Embodiment> The inventors of the present invention have carried out intensive development aimed at densifying the hardened concrete by incorporating material particles with different hardening reaction onset times into the hardened concrete, and inducing a hardening reaction according to the particle size. Conventional concrete using industrial by-products as hardened concrete has focused on ensuring early strength development by adjusting the types of materials used and their mixing ratios. In this invention, we have not only adjusted the types, mixing ratios, and proportions of materials to be mixed into the hardened body, but also carried out extensive experiments and development with the aim of improving the density of the hardened body in the areas excluding the fine and coarse aggregates by varying the particle size of the materials to be mixed, or the specific surface area of ​​the material particles, or the time it takes for the materials to start to undergo a hardening reaction.

[0012] Specifically, in concrete made with conventional ordinary Portland cement, or blast furnace cement or fly ash cement, the volume of pores in the range of 3 nm to less than 0.01 μm, which affect the durability of the concrete, could not be reduced by increasing the curing period, out of the capillary voids that are distributed over a wide range from 3 nm to 30 μm within the voids that exist in the part of the concrete excluding the fine and coarse aggregates. Therefore, in this invention, by adjusting the type, particle size, or specific surface area of ​​the materials used while taking into account the difference in the time until the hardening reaction of the mixed materials begins, it is possible to further densify the portion of the hardened body excluding the fine and coarse aggregates, thereby reducing the pore volume from 3 nm to less than 0.01 μm. The portion of the hardened body excluding the fine and coarse aggregates can be filled with pores (hereinafter referred to as "pores") of various diameters present in the hardened body, such as gel voids, capillary voids, micropores, mesopores, and macropores. As a result, it was confirmed that the concrete can be significantly densified compared to conventional concrete (referring to concrete mixed by setting the type of materials and particle size without considering the difference in the time until the hardening reaction of the material particles begins).

[0013] To explain in more detail, the method for mixing a hardened body according to this embodiment is characterized in that water, a hydration-reactive material, a pozzolanic-reactive material, a latent hydraulic material, slaked lime, a hydroxide ion supplying material, an expansive material, fine aggregate, coarse aggregate, and a high-performance water-reducing agent are mixed, and the hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared in terms of particle size or specific surface area in accordance with the differences in the types of hardening reactions of the materials, so that the portions of the hardened body excluding the fine aggregate and coarse aggregate are densified. By adjusting the properties of the materials mixed into the hardened body in this way, the hardened body can be made denser, which improves its resistance to corrosion by sulfuric acid and chemicals, penetration by hydrogen sulfide and carbon dioxide, and intrusion by seawater.

[0014] Hereinafter, the details of the embodiment of the method for compounding the cured product of the present invention will be described. The method for blending a hardened body according to this embodiment reduces the pores present in the portion of the hardened body excluding the fine and coarse aggregates. Then, the particle size or specific surface area is set while taking into consideration the difference in the time it takes for the hardening reaction of the material particles to begin, which is necessary to reduce the total pore volume. This allows the hardening reaction products generated and precipitated on the particle surfaces by the hardening reaction of the material particles to fill and densify the particles.

[0015] Specifically, in the method for blending a hardened body according to this embodiment, one or more types of materials are blended into the portion of the hardened body excluding the fine aggregate and coarse aggregate. When one type is used, particles with two different particle sizes or particles with two different specific surface areas are blended in consideration of filling the pores present in the portion of the hardened body excluding the fine aggregate and coarse aggregate. In addition, when two or more types of hydration-reactive materials, latent hydraulic materials, and pozzolanic-reactive materials are mixed, the particle size of each material particle is adjusted taking into consideration the filling of pores present in the part of the hardened body excluding fine aggregate and coarse aggregate. In this case, the larger the particle size or the smaller the specific surface area of ​​the material to be mixed into the hardened body, the longer it takes for the material to begin to harden. Specifically, when mixing two types of materials, the larger particle size can be a pozzolanic reactive material that begins to harden slowly, and the smaller particle size can be a latent hydraulic material or hydration reactive material that begins to harden quickly.

[0016] The combinations of hardening reactions when the two types of materials mentioned above are blended are (1) pozzolanic reaction (material with large particle size or small specific surface area) and latent hydraulic reaction (material with small particle size or large specific surface area), (2) pozzolanic reaction (material with large particle size or small specific surface area) and hydration reaction (material with small particle size or large specific surface area), or (3) either latent hydraulic reaction or hydration reaction, or material with large particle size or small specific surface area, or material with small particle size or large specific surface area. In addition, combinations of large particle size, particles smaller than particles with small specific surface area, or particles with large specific surface area that start to harden quickly are possible.

[0017] Specifically, in the method for blending a hardened body according to this embodiment, the hydration-reactive material includes any one or any combination of Portland cement, blast-furnace cement, fly ash cement, calcium hydroxide, and other materials that undergo a hydration reaction and harden. Among these, the Portland cement may be ordinary Portland cement, high-early-strength Portland cement, moderate-heat Portland cement, or low-heat Portland cement. Furthermore, materials that harden by undergoing a hydration reaction other than these may also be, for example, inorganic compounds that are used to produce hardened bodies similar to concrete.

[0018] On the other hand, the latent hydraulic material includes any one or any combination of ground granulated blast furnace slag, sewage sludge incineration ash, and other materials that undergo a hydraulic reaction and harden in an alkaline atmosphere. The pozzolanic reactive material includes any one or any combination of fly ash, sewage sludge incineration ash, silica fume, fine volcanic glass powder for concrete, pozzolanic reactive materials, and other materials that undergo a pozzolanic reaction and harden when stimulated by alkali.

[0019] More specifically, in the method for compounding the hardened body according to this embodiment, fly ash (hereinafter also abbreviated as "FA") and ground granulated blast furnace slag (hereinafter also abbreviated as "BFS") are used as the main ingredients, similar to the acid-resistant concrete described in Patent Document 1, and industrial by-products including "super ash" (hereinafter also abbreviated as "SA"), which is sewage sludge incineration ash that has been particle-sized, and silica fume (hereinafter also abbreviated as "SF") are blended in. Hereinafter, the hardened body according to this embodiment will also be referred to as "IBPM" (Industrial By-Product Materials). Here, the following Table 1 shows an example of the physical properties (properties), specific gravity, specific surface area, particle size, and hardening reaction conditions of the materials used in the compounding method for the hardened body according to this embodiment.

[0020] [Table 1]

[0021] In this embodiment, as described above, the setting is made based on the types of materials with different particle sizes or different specific surface areas, and the difference in the time until the onset of the hardening reaction. The characteristics of these materials blended into the cured product according to this embodiment are as follows.

[0022] The SF in this embodiment is mostly amorphous, spherical silica (SiO2) collected as dust in the exhaust gas from an electric arc furnace. Silica fume is a spherical material similar to fly ash, but its particle size is even smaller than that of fly ash.

[0023] As the sewage sludge incineration ash according to this embodiment, SA, which is obtained by adjusting the particle size of sewage sludge incineration ash as described in Patent Document 1, was used. SA is made by crushing and pulverizing sewage sludge incineration ash to a specific particle size, and exhibits hydraulic properties similar to ground granulated blast furnace slag. The particle size distribution of SA is wider than that of FA or ground granulated blast furnace slag. For this reason, it is a material composed of particles with smaller particle sizes that harden through a latent hydraulic reaction, while larger particles exhibit a pozzolanic reaction. In this embodiment, SA is such that materials with particle sizes smaller than the average particle size in the particle size distribution with the average particle size calculated from the specific surface area and specific gravity as the median exhibit the properties of latent hydraulic materials, and materials with particle sizes larger than the average particle size exhibit the properties of pozzolanic reactive materials.

[0024] The BFS according to this embodiment is a fine powder that is a by-product in the pig iron manufacturing process. BFS has a "latent hydraulic property" that hardens by generating calcium silicate hydrate and calcium aluminate hydrate. It hardens when water is supplied and an alkaline stimulant is added. It is the material that mainly generates strength in the hardened body according to this embodiment.

[0025] The FA in this embodiment is polazon coal ash (fly ash) for concrete, which is collected by dust collectors from pulverized coal combustion at thermal power plants. Fly ash is primarily composed of silica and alumina, and hardens in an alkaline atmosphere when exposed to an alkaline stimulant through a pozzolanic reaction that produces calcium silicate hydrate and other compounds. Specifically, the FA according to this embodiment is a spherical material with a particle size of more than 7 μm.

[0026] In addition to these, materials related to the densification according to this embodiment other than fly ash, ground granulated blast furnace slag, sewage sludge incineration ash, and silica fume can also be used as materials. For example, ground volcanic glass for concrete, ground waste glass, and concrete materials that harden in an alkaline atmosphere can also be used.

[0027] Hereinafter, in this embodiment, the latent hydraulic material includes, for example, either BFS and SA or any combination thereof. In this embodiment, the pozzolanic reactive material is characterized by including any one or any combination of FA, SA, and SF.

[0028] The hydroxide ion supply material according to this embodiment may contain any one or any combination of potassium hydroxide, potassium carbonate, and hydrated lime. When potassium carbonate dissolves in water, it decomposes into KOH and H2CO3 by hydrolysis, and KOH further decomposes into K + and OH - ionized into OH - It is believed that this liberates hydroxide ions and acts as an inducer for the latent hydraulic reaction or pozzolanic reaction. In other words, in this embodiment, in a broad sense, it is possible to use a material that supplies hydroxide ions during the reaction of the hardened body. Furthermore, it is also possible to use hydroxide ion compound materials other than those mentioned above.

[0029] To explain in more detail, the method for mixing a hardened body according to this embodiment focuses on the difference between the particle size of the materials to be mixed and the time when the hardening reaction begins to occur, and prepares a mixture of a hydration-reactive material, a latent hydraulic material, and a pozzolanic-reactive material so that the particles mixed into the concrete reduce the diameter of the pores present in the part of the hardened body excluding the fine aggregate and coarse aggregate, thereby densifying this part.

[0030] That is, in the method for compounding a hardened body according to this embodiment, the time at which the hardening reaction begins to occur is set according to the particle size of the compounded materials and the type of hardening reaction of the materials. This fills the pores in the hardened body, excluding the fine and coarse aggregates, with the hardening reaction product that precipitates on the surfaces of the mixed material particles. As a result, the pore diameter and volume of the pores in the hardened body are reduced, making the above-mentioned parts denser.

[0031] Specifically, in the method for blending a hardened body according to this embodiment, a pozzolan-reactive material and a latent hydraulic material or a hydratable material are combined and blended for materials ranging from large to small particle size.

[0032] More specifically, in the method for blending a hardened body according to this embodiment, the particle sizes of the hydration reactive material, latent hydraulic material, and pozzolanic reactive material to be blended are adjusted from small to large, and further, the hardening reaction is initiated in the order from small to large diameter materials. This improves the ability to fill voids compared to ordinary Portland cement, which contains a single particle of the same particle size that begins the hardening reaction simultaneously, and makes it possible to densify the hardened body of this embodiment, excluding the fine aggregate and coarse aggregate.

[0033] Alternatively, the sizes of the particles to be mixed are combined in accordance with the difference in the time it takes for the hydration reactive material, latent hydraulic material, and pozzolanic reactive material to begin to exhibit hardening reactions. This also makes it possible to reduce the volume of pores present in the hardened body excluding the fine aggregate and coarse aggregate by the hardening reaction product, which is a precipitate deposited on the surface of the particles.

[0034] More specifically, it is effective to combine a variety of hydration-reactive materials, or latent hydraulic materials and pozzolanic-reactive materials, ranging from materials with small particle sizes or large specific surface areas to materials with large particle sizes or small specific surface areas. In this case, it is preferable to mix SA whose particle size is distributed over a wide range and which exhibits the hardening reactivity of both a latent hydraulic material and a pozzolanic reactive material depending on the particle size of the material.

[0035] By configuring the material in this manner, small particles or materials with large specific surface areas begin to harden after the materials are mixed, and as the curing period increases, large particles or materials with small specific surface areas begin to harden. As a result, the pores in the hardened body excluding the fine and coarse aggregates are filled with hardening reaction products generated on the particle surfaces, resulting in densification. These hardening reaction products include calcium silicate, calcium hydroxide, calcium aluminosilicate hydrate, calcium silicate hydrate, hydrotalcite, ettringite, and monosulfate.

[0036] In summary, in this embodiment, the hardened body is formulated in order of particle size from largest to smallest: FA (a pozzolanic reactive material), BFS (a latent hydraulic material), SA (a latent hydraulic material), SA (a pozzolanic reactive material), and SF (a pozzolanic reactive material). This allows the hardening reaction of the smaller particles or larger specific surface area materials to occur before the hardening reaction of the larger particles or smaller specific surface area materials. This prevents the expanded cylindrical or conical pores from being blocked by the hardening reaction products deposited on the particle surfaces, preventing the supply of the hardening reaction materials necessary for the hardening of the smaller particles or larger specific surface area particles (SF in this embodiment) in the narrowed pores. This allows all the material particles to harden, depositing the hardening reaction products on the particle surfaces, thereby reducing the pore diameter and cumulative pore volume in the hardened body, excluding the fine and coarse aggregates.

[0037] Furthermore, in this embodiment, the portion of the hardened body excluding the fine aggregate and coarse aggregate is composed of latent hydraulic materials and pozzolanic reactive materials of different particle sizes, as shown in the physical properties of the materials in Table 1. The latent hydraulic materials exhibit a faster hardening reaction than the pozzolanic reactive materials. For this reason, by making the particle size of the latent hydraulic material blended into the hardened body smaller than that of the pozzolanic reactive materials or by increasing the specific surface area, the precipitation of the hardened product on the particle surfaces does not block the expanded bottoms of the cylindrical or conical pores, preventing the movement of substances necessary for the hardening reaction to the narrowed ends of the pores. By blending a pozzolanic reactive material that takes a long time to initiate the hardening reaction and has a large particle size or a small specific surface area, it is possible to continue supplying the substances necessary for the pozzolanic reaction necessary for the hardening of the pozzolanic reactive material with a small particle size or a large specific surface area up to the narrow end of the cylindrical or conical pores, and further, until the hardening reaction of the pozzolanic reactive material is complete, thereby promoting the hardening reaction of SF, the pozzolanic reactive material present in the narrow end of the pores, and precipitation of the hardening reaction products on the particle surfaces.

[0038] The composition for hardened body according to this embodiment may be provided in the form of a premix or mixture (hereinafter simply referred to as "mixture") obtained by removing water from the materials mixed by the above-described method for mixing a hardened body. This mixture may also be provided in a form that further removes one or any combination of coarse aggregate, sand contained in fine aggregate, and a high-performance water-reducing agent. In this case, the mixing ratio may be changed depending on whether the product is precast or cast in place.

[0039] The hardened body according to this embodiment may be produced by compacting using centrifugal molding, vibrating molding, or by pouring at the site.

[0040] Specifically, the hardened product according to this embodiment can be used to manufacture precast concrete. This precast concrete is suitable for products that require particularly high strength. When manufacturing concrete products in a dedicated factory, setting the optimal composition and strength can improve manufacturing efficiency and optimize manufacturing costs.

[0041] The hardened body according to this embodiment may be compacted by centrifugal compaction. In this centrifugal compaction, a mixture (hereinafter simply referred to as the "mixture") containing water, latent hydraulic material, pozzolanic reactive material, hydroxide ion supply material, expansive material, fine aggregate, coarse aggregate, and high-performance water-reducing agent in the above-mentioned proportions is filled into a centrifugal compaction form, which is then rotated at high speed on a compacting machine. Finally, the mixture is compacted at an acceleration of approximately 30 to 50 G using centrifugal force, and excess water is discharged as sludge. The acceleration may be increased in several stages to ensure adequate drainage of excess water and dense compaction. For example, compaction is performed at 5 G, 15 G, and 35 G for 1 minute, 1 minute, and 7 minutes, respectively. By producing the hardened body using centrifugal compaction in this way, it is possible to increase not only the strength but also the acid resistance of the hardened body according to this embodiment, and further to shorten the steam curing time, thereby making it possible to produce high-performance cylindrical structures, etc.

[0042] Furthermore, the hardened body of this embodiment can be used as precast concrete formed by vibration in addition to the above-mentioned centrifugal molding. Examples of vibration-molded products include box culverts and manholes. Both of these products can be manufactured using the same manufacturing process as precast concrete products such as Hume pipes. In other words, they can be manufactured simply by replacing centrifugal molding with vibration molding. Therefore, the mixture of this embodiment can also be applied to the manufacture of vibration-molded precast concrete products.

[0043] In this case, the cured product of this embodiment may have different required performance depending on the product to which it is applied. In this case, it is possible to achieve this by simply fine-tuning the ratio (W / P) of the water (W) to the total powder (P) in the mixture so that it corresponds to the ratio (W / C) of water (W) to cement (C) in concrete. Alternatively, instead of W / P, it is also possible to adjust the water (W) to binder (B) ratio (hereinafter referred to as "W / B"). Here, the W / B in this embodiment can be decreased or increased within a range that satisfies the required performance of strength and fluidity.

[0044] Furthermore, by adjusting the fine aggregate ratio (s / a) and the amount of admixture (Ad) added as needed, it is possible to match the fresh properties of the mixture (slump: SL and air content: Air) to the required performance of the product to be applied. Furthermore, if an appropriate curing method and temperature control are implemented, the mixture of this embodiment can also be poured on-site.

[0045] Furthermore, the hardened body according to this embodiment is characterized in that it is steam cured after molding, and the pre-curing time for this steam curing is 1.5 hours or more. Precast concrete is sometimes steam cured to shorten the time until demolding and increase production efficiency. In this case, it is preferable to adjust the steam curing conditions, such as pre-curing time, temperature rise (heating), maximum temperature, holding time, and cooling method, depending on the target product and mix conditions. Of these, the pre-curing time is the time from when water is poured until the temperature starts to rise. In this embodiment, for example, the pre-setting time is 1.5 to 6 hours, the temperature is increased at a rate of 15 to 25°C / hour, and the mixture is maintained at 60 to 75°C for 3 to 5 hours or more, and then the mixture is slowly cooled to the laboratory temperature and cured in air. By performing steam curing under such conditions, the setting and hardening of the mixture (strength development) can be accelerated, and production efficiency can be improved.

[0046] Furthermore, the hardened body according to this embodiment is characterized in that it may be subjected to high-pressure and high-temperature curing after molding. That is, strength can be further increased by combining autoclave curing (high-pressure, high-temperature curing). The high-pressure, high-temperature curing conditions include, for example, curing in a high-temperature, autoclave at 90 to 220°C for about 1 to 6 hours.

[0047] Furthermore, the slump flow of the hardened product according to this embodiment is preferably about 550±100 mm. In other words, the fresh properties of the mixture according to this embodiment are high fluidity. This improves the filling ability into the formwork during molding, allows excess water to be smoothly drained as sludge water, and enables good compaction effects. Furthermore, the weight ratio of water to the mixture (hereinafter simply referred to as the "water-powder ratio") is about 20 to 60%.

[0048] The air content of the cured body according to this embodiment is preferably 2.0±1.5%, that is, 0.5 to 3.5%, which allows the desired strength to be obtained while improving workability. In this embodiment, the air content can be adjusted using an air entraining (AE) agent or other air content regulator. Examples of AE agents include various anionic, cationic, nonionic, and amphoteric surfactants. Examples of anionic surfactants include resin-based, alkylbenzene sulfonic acid-based, and higher alcohol ester-based surfactants. In this embodiment, it is particularly preferable to use a modified rosin acid compound-based anionic surfactant. It is also possible to use an AE water-reducing agent that has the properties of both an AE agent and a water-reducing agent.

[0049] The cured product according to this embodiment may contain fibers or the like. Examples of such fibers include various organic or inorganic fibrous materials such as vinylon fibers, acrylic fibers, carbon fibers, and metal fibers. In addition, zeolite, siliceous fine powder, calcium carbonate, clay minerals such as bentonite, gypsum, calcium silicate, and the like may also be appropriately blended.

[0050] Furthermore, in the hardened body according to this embodiment, other additives such as superplasticizers, retarders, waterproofing admixtures, moisture-proofing admixtures, foaming agents, thickeners, antifreeze agents, colorants, workability enhancers, anti-slip agents, antifoaming agents, setting regulators, shrinkage reducing agents, cement quick hardening agents, polymer emulsions, etc. can be appropriately blended.

[0051] The hardened body according to this embodiment can also be used for purposes other than precast concrete produced by centrifugal molding. For example, the hardened body according to this embodiment can also be used in ordinary construction, various production and manufacturing facilities, and the like.

[0052] In addition, as the industrial by-product of this embodiment, materials other than FA, ground granulated blast furnace slag, sewage sludge incineration ash, and silica fume can also be used. For example, incineration ash from a biomass power plant, soot dust, residues from mineral refining, and the like, which contain Ca, Si, various inorganic metals, etc., can also be used. Furthermore, as the sewage sludge incineration ash, materials other than the super ash described in Patent Document 1 can also be used. In addition to slaked lime, alkali metal hydroxides such as sodium hydroxide, gypsum, etc. can also be used as the alkaline stimulant. [Example]

[0053] Hereinafter, examples of the present invention will be described with reference to the drawings, but the present invention is not limited to these examples.

[0054] (Formulation examples of hardened composition and hardened product) In this example, the materials shown in Table 1 were mixed, taking into consideration the diameter or specific surface area of ​​the mixed material particles and the difference in the speed of the material's hardening reaction, and air curing tests were conducted in a constant temperature and humidity chamber at a temperature of 20°C and a relative humidity of 50% until the material reached an age of 14 and 91 days. This was used to investigate whether the total pore volume of the hardened body according to this example, excluding the fine aggregate and coarse aggregate, could be reduced.

[0055] First, the material ratio table of the hardened body according to this example is shown in Table 2 below. 3 The compounding ratio and unit weight ratio are per unit.

[0056] [Table 2]

[0057] The composition of the hardened body according to this example is shown in Table 3 below. 3 An example of a suitable blend is shown below.

[0058] [Table 3]

[0059] (Production and testing of hardened compositions and hardened bodies) The hardened body composition of this example was produced by mixing the IBPM listed in Table 1 with FA, a pozzolanic reactive material, BFS, a latent hydraulic reactive material, SA, which has the properties of both a latent hydraulic material and a pozzolanic reactive material, and SF, a pozzolanic reactive material, in the proportions shown in Table 2. The materials were then mixed according to the proportions listed in Table 3 to produce IBPM concrete as the hardened body of this example. Then, at ages of 14 and 91 days, the pore size distribution was measured in the hardened body after removing the fine and coarse aggregates using a mercury intrusion porosimeter.

[0060] (result) First, the types and particle sizes of material particles to be mixed into the concrete were set in accordance with the above-described embodiment. Figure 1 shows the results of measurements of the reduction in pore volume due to hardening reaction products on the particle surfaces of IBPM concrete mixed using the mixing method of this example. Specifically, the pore distribution of the hardened concrete, excluding the fine and coarse aggregates, was measured using a mercury intrusion porosimeter. Figure 1(a) shows the results measured after air curing for 14 days, and Figure 1(b) shows the results measured after air curing for 91 days. In each graph, the left vertical axis represents cumulative pore volume (ml / g), the right vertical axis represents pore volume (ml / g), and the horizontal axis represents pore diameter (μm). The solid line represents pore volume (ml / g), and the dashed line represents cumulative pore volume (ml / g).

[0061] As a result, when the curing period of the hardened body (IBPM concrete) containing IBPM of this example was extended from 14 days to 91 days, the pore volume of the pores with diameters in the range of 0.003 μm to 0.010 μm shown in Figure 1 (a) decreased, and the parts of the hardened body excluding the fine aggregate and coarse aggregate became dense. Specifically, when the air curing age of the hardened body containing IBPM increased from 14 days to 91 days, the total pore volume of the hardened body excluding the fine and coarse aggregates decreased from 0.211 ml / g to 0.169 ml / g. In other words, the volume of the pores in the hardened body excluding the fine and coarse aggregates decreased.

[0062] In this way, it was shown that differences in the size or specific surface area of ​​the material particles mixed into the hardened body and differences in the time it takes for the hardening reaction of the material particles in the hardened body to begin are related to the densification of the part of the hardened body excluding the fine aggregate and coarse aggregate.

[0063] Next, the type of material of the hardened body, the size of the material particles used, the pore diameter and pore volume of the pores present in the part of the hardened body excluding the fine aggregate and coarse aggregate, as well as the pore diameter and cumulative pore volume were measured. Specifically, OPC (hereinafter simply referred to as "OPC") composed of one type of mixed material was used as a comparative example, and FC concrete (hereinafter simply referred to as "FC") composed of two types of mixed materials, with differences in the time at which the hardening reaction of the materials began to occur, was used as the present example.The pore size distribution, pore volume, and cumulative pore volume of the portion excluding the fine aggregate and coarse aggregate were measured using a mercury intrusion porosimeter.

[0064] Table 4 shows the specific gravity, specific surface area, particle size, and 1m2 of the material for each hardened body of OPC and FC, which verify the relationship between the particle size of the material particles and the occurrence of the hardening reaction. 3 Indicates the unit weight per unit.

[0065] [Table 4]

[0066] In Table 4, as mentioned above, OPC is a hardened product of ordinary Portland cement. FC is a hardened product made by blending ordinary Portland cement with other materials. FC is a hardened product made by blending fly ash, which has a larger particle size or a smaller specific surface area than ordinary Portland cement and takes longer to initiate the hardening reaction.

[0067] Here, OPC is composed of a single hardening reaction material with the same particle size or specific surface area and no difference in the time it takes for the hardening reaction to begin. FC is composed of fly ash, a pozzolanic reaction material with a large particle size or small specific surface area and a slow hardening reaction to begin, and ordinary Portland cement, a hydration reaction material with a smaller particle size or a larger specific surface area than fly ash and a faster hardening reaction to begin. That is, here, OPC is the comparative example, and FC is the present embodiment.

[0068] Table 5 shows the relationship between the particle size of the material and the hardening process. 3 The compound weight per unit is shown.

[0069] [Table 5]

[0070] As a comparative example, Figure 2 shows the results of measurements using a mercury intrusion porosimeter to examine the reduction in pore volume due to hardening reaction products on the particle surfaces of OPC concrete, excluding the fine and coarse aggregates. Figure 2(a) shows the results measured after air curing for 14 days. Figure 2(b) shows the results measured after air curing for 91 days. In each graph, the left vertical axis represents cumulative pore volume (ml / g), the right vertical axis represents pore volume (ml / g), and the horizontal axis represents pore diameter (μm). The solid line represents pore volume (ml / g), and the dashed line represents cumulative pore volume (ml / g).

[0071] As a result, as the period of air curing increased from 14 days in Figure 2(a) to 91 days in Figure 2(b), the volume of large pores exceeding 0.3 μm (Figure 2(a)) decreased, and the volume of pores with diameters in the range of 0.3 μm to 0.006 μm (Figure 2(b)) increased. On the other hand, the volume of pores with diameters less than 0.006 μm (Figure 2(c)) did not decrease.

[0072] That is, when a single type of material, particle size, or material particles with a single specific surface area produced by OPC was mixed, the volume of pores with a diameter exceeding 0.3 μm among the pores with a radius of 3 nm to 30 μm (hereinafter referred to as "capillary voids") present in the hardened body excluding the fine and coarse aggregates was reduced. However, the volume of pores with a diameter of less than 0.006 μm was not reduced.

[0073] In other words, for a mix with one type of hardening reaction material and a single particle size or specific surface area, even if the air curing period was increased from 14 days to 91 days, the pore size distribution of particles with a diameter of less than 0.006 μm did not change, as shown in Figure 2(c), and the pore diameter could not be reduced by the occurrence of the hardening reaction of the material particles. Therefore, it was shown that when material particles with a single particle size or specific surface area are blended together, there is no difference in the time until the hardening reaction begins, and the hardened body contains material particles with a single particle size or specific surface area, the pore size distribution changes but the total pore volume does not decrease.

[0074] Next, in this example, the pore size distribution of FC concrete was measured using two types of material particles: hydration-reactive material and pozzolanic-reactive material. The larger particles were used as the pozzolanic-reactive material and the smaller particles were used as the hydration-reactive material. Specifically, the two types of materials used were hydration-reactive material and pozzolanic-reactive material, and two different particle sizes or two different specific surface areas were used. The larger particle size was fly ash, while the smaller particles or particles with a large specific surface area were ordinary Portland cement. The time until the hardening reaction began was shorter for ordinary Portland cement, which is a hydration-reactive material, and later for fly ash, which is a pozzolanic-reactive material.

[0075] Figure 3 shows the reduction in pore volume due to hardening reaction products on the particle surfaces of FC concrete. Specifically, the pore distribution of pores present in the area excluding fine and coarse aggregates was measured using a mercury intrusion porosimeter. Figure 3(a) shows the measurement results after air curing for 14 days. Figure 3(b) shows the measurement results after air curing for 91 days. The vertical axis on the left side of the figure represents cumulative pore volume (ml / g), the vertical axis on the right side represents pore volume (ml / g), and the horizontal axis represents pore diameter (μm). The solid line in the figure represents pore volume (ml / g), and the dashed line represents cumulative pore volume (ml / g).

[0076] As a result, the pore distribution of the hardened concrete, excluding the fine and coarse aggregates, made with fly ash cement type B, which is composed of particles of two types of materials, showed that as the air curing age increased from 14 to 91 days, the volume of pores with diameters of less than 0.03 μm decreased, as shown in "A" in Figure 3. Furthermore, as shown in "B" in Figure 3, the volume of pores with diameters of less than 0.006 μm, which is smaller than the lower limit of capillary voids, also decreased.

[0077] In other words, by shortening the time it takes for the hardening reaction to begin in ordinary Portland cement, which has particles with a small particle size or a large specific surface area, compared to fly ash, which has particles with a large particle size or a small specific surface area, it was possible to reduce the volume of pores with a pore diameter of less than 0.006 μm, which is smaller than the lower limit of capillary voids.

[0078] In this way, in a hardened body made by blending materials that take different times until the hardening reaction begins, the particle size or specific surface area of ​​the material that takes the earliest time to begin the hardening reaction is reduced, or the specific surface area is increased, and the particle size or specific surface area of ​​the material that takes the latest time to begin the hardening reaction is increased, thereby reducing the pore volume of the pores that exist in the part of the hardened body excluding the fine aggregate and coarse aggregate, and that have a pore diameter of less than 0.006 μm, which is smaller than the lower limit of capillary voids, and making the body more dense.

[0079] [Salt damage resistance test] Next, as a salt damage resistance test, the hardened IBPM concrete and OPC concrete were cured in air in a constant temperature and humidity chamber at a temperature of 20°C and a relative humidity of 50% until they reached an age of 14 days. 3 An immersion test was carried out for 91 days using an aqueous solution of the above. As a result, it was confirmed that reducing the total pore volume of the hardened body excluding fine and coarse aggregates and reducing the pore diameter can suppress the amount of chloride ions that penetrate from the surface of the hardened body to the interior, and can also suppress the movement of chloride ions, which is a factor that determines the penetration distance. The salt damage resistance test according to this example will be described in detail below.

[0080] (Production and testing of hardened bodies) Table 6 shows the hardened body 1m according to this example. 3 The compound weight per unit is shown.

[0081] [Table 6]

[0082] A hardened IBPM concrete body was produced by mixing the mixture proportions shown in Table 6 above, and a hardened OPC concrete body was produced as a comparative example. The mixture proportions other than those shown in Table 6 are the same as those in Tables 2 and 4 above. These hardened materials were treated at a chloride ion concentration of 10 kg / m after 14 days. 3 The specimens were immersed in a saline solution (hereinafter referred to as the "immersion aqueous solution") for 91 days. After that, cylindrical cores 10 cm in diameter were taken from the surface. A mercury intrusion porosimeter was then used to measure the pore size distribution in the area excluding the fine and coarse aggregates. Furthermore, the amount of salt that migrated from the surface to the depths was measured using the area analysis method for elements in concrete using an EPMA (Electron Probe Micro Analyzer) specified in JIS-A1154 and JSCE-G574.

[0083] (result) The results of this immersion test will be described with reference to FIGS. First, the results of the hardened IBPM concrete will be described with reference to FIGS. Figure 4 shows the diameter and volume of pores in the portion of IBPM concrete excluding the fine and coarse aggregates after 14 days of air curing, as well as the cumulative pore volume of the pores. The vertical axis on the left shows cumulative pore volume (ml / g), the vertical axis on the right shows pore volume (ml / g), and the horizontal axis shows pore diameter (μm). The solid line in the figure shows pore volume (ml / g), and the dashed line shows cumulative pore volume (ml / g).

[0084] As shown in Figure 4, the voids in the IBPM concrete excluding the fine and coarse aggregates were distributed with pore diameters ranging from 0.003 μm to 0.050 μm, with the maximum pore volume being 0.018 μm in diameter (pore volume: 0.0421 ml / g). The cumulative pore volume of pores in this range was 0.2055 ml / g, accounting for 97.4% of the total pore volume (0.211 ml / g) of the IBPM concrete excluding the fine and coarse aggregates. Furthermore, the pores comprising the voids in the IBPM concrete excluding the fine and coarse aggregates were classified as mesopores, with pore diameters of 0.050 μm or less. Specifically, most pore diameters were in the 0.002 μm to 0.050 μm range.

[0085] Figure 5 is a graph showing the change in chloride ion concentration from the surface to the depth of IBPM concrete that was immersed in an immersion solution for 91 days after curing up to 14 days. The vertical axis shows the chloride ion concentration (kg / m 3 ) and the horizontal axis indicates the distance (mm) from the surface of the hardened body.

[0086] Range (A) in Figure 5 is the point where the chloride ion concentration in IBPM concrete gradually increases to that of the aqueous solution, and this was at a distance of just 0.3 mm from the surface. As shown in Figure 5, the pores in IBPM concrete are made up of tiny mesopores, so the penetration of chloride ions into IBPM concrete is affected by the surface tension of the aqueous solution. Therefore, it is thought that mesopores have a greater effect in inhibiting chloride ions from passing through the surface and penetrating deeper than macropores or pores larger than them.

[0087] Area (b) in Figure 5 is the area where the amount of chloride ions in the pores has increased, resulting in an increase in chloride ion concentration. In this area, the chloride ion aqueous solution that has penetrated into the IBPM concrete is absorbed into the mesopores by capillary action, and then the chloride ions are sorbed on the inner surface of the mesopores. As this sorption area expands due to capillary action, the amount of chloride ions sorbed increases and the aqueous solution held in the mesopores becomes diluted. It is thought that chloride ions then move from the outside into the diluted aqueous solution inside the mesopores by concentration diffusion. Here, the increase in chloride ion concentration decreased as one went deeper into the hardened body. This is thought to be because the voids are mainly composed of mesopores, as shown in Figure 4. In other words, the surface tension of the aqueous solution and the suppressing effect of the capillary action of the mesopores described above inhibit the movement of the aqueous solution from the surface to the depths, and therefore the chloride ions that try to penetrate through the surface decrease as one goes deeper.

[0088] More specifically, as shown in range (c) of Figure 5, the concentration of chloride ions gradually decreased with increasing depth. This is thought to be because, as mentioned above, the pores that make up the voids in the IBPM concrete where the fine and coarse aggregates have been removed are primarily mesopores. In other words, mesopores, due to their diameter and the surface tension of the chloride ion aqueous solution, inhibit the movement of chloride ions that pass through the surface and penetrate into the interior. Furthermore, as the aqueous solution moves from the surface into the mesopores deeper, the movement itself is thought to be suppressed by the suppressing effect of the capillary action of the mesopores.

[0089] Next, the results of the hardened body of OPC concrete, which is a comparative example, will be described with reference to FIGS. Figure 6 shows the diameter and volume of pores in the OPC concrete excluding the fine and coarse aggregates after 14 days of air curing, as well as the cumulative pore volume of the pores. The vertical axis on the left shows cumulative pore volume (ml / g), the vertical axis on the right shows pore volume (ml / g), and the horizontal axis shows pore diameter (μm). The solid line in the figure shows pore volume (ml / g), and the dashed line shows cumulative pore volume (ml / g).

[0090] In the area of ​​the OPC concrete shown in Figure 6, where the fine and coarse aggregates had been removed, a wide range of pore sizes was found, from mesopores with diameters of 0.002 to 0.050 μm to macropores with diameters exceeding 0.050 μm. The cumulative pore volume of pores smaller than mesopores in the OPC concrete was 0.1326 ml / g, accounting for 54.3% of the total pore volume (0.244 ml / g). The volume of pores larger than mesopores accounted for 45.7% of the total pore volume. Of these, pores larger than macropores ranged in diameter from over 0.050 μm to several μm.

[0091] As such, the pores in OPC concrete are composed of mesopores and macropores. In other words, the diameter of the pores that make up the pores in OPC concrete is larger than that in IBPM concrete. For this reason, the surface tension of the aqueous solution containing chloride ions is less likely to hinder the penetration of the solution through the surface of the OPC concrete into the depths. In other words, it is thought that the hindering effect of the surface tension of the aqueous solution is small, and the concrete is easily filled with the aqueous chloride ion solution.

[0092] Figure 7 is a graph showing the change in chloride ion concentration from the surface to the depth of OPC concrete that was immersed in an immersion solution for 91 days after aging 14 days. The vertical axis shows the chloride ion concentration (kg / m 3 ) and the horizontal axis indicates the distance (mm) from the surface of the hardened body.

[0093] In OPC concrete, the distance from the surface (mm) shown in range (B) and the chloride ion concentration (kg / m 3 ) at a depth of 2 mm from the surface, the concentration of chloride ions reaches its maximum concentration of 23.8 kg / m 3 At a depth of 0.5 mm from that point, the concentration was 9.0 kg / m 3 (14.8 kg / m 3 ) and the concentration of chloride ions decreased to 0.0 kg / m3 as shown in range (C). 3 A point was formed where the temperature gradually decreased to

[0094] Range (b) in Figure 7 is an area with a high chloride ion concentration. As mentioned above, chloride ions that penetrate OPC concrete move together with water as an aqueous solution. Specifically, when OPC concrete is immersed in an aqueous chloride ion solution, the pores on the surface have an effect of inhibiting the penetration of the solution due to surface tension. This inhibiting effect varies depending on the size of the pores, with macropores with larger diameters having a smaller inhibiting effect. For this reason, the aqueous chloride ion solution that penetrates the macropores is easily absorbed inside and then moves to deeper pores by capillary action. As mentioned above, OPC concrete has many such macropores.

[0095] Here, the chloride ion aqueous solution that passes through the surface of the OPC concrete is held inside both macropores and mesopores by capillary action, and chloride ions are sorbed on their inner surfaces. In all mesopores, macropores, and pores larger than macropores, this sorption, along with the dilution of the chloride ion concentration in the aqueous solution inside the pores due to sorption, the increase in the amount of chloride ions inside the pores due to the movement of chloride ions through the surface to deeper pores and chloride ions outside the pores, and the movement of the chloride ion aqueous solution to deeper pores by capillary action, occur simultaneously.

[0096] However, unlike mesopores, macropores have a weaker ability to retain the chloride ion solution stored inside them through capillary action. Therefore, compared to mesopores, the chloride ion solution stored in macropores moves more easily to other pores that do not store the solution or are not completely saturated with the solution. For this reason, it is thought that the inhibitory effect on the penetration of chloride ion solution through the surface of OPC concrete is smaller than that of IBPM concrete.

[0097] As mentioned above, OPC concrete contains a mixture of pores larger than macropores, through which the chloride ion solution can easily pass, and mesopores, through which it is difficult to pass. As mentioned above, mesopores are smaller than macropores, and therefore have a stronger inhibitory effect on the penetration of the solution due to surface tension than macropores. For this reason, even in OPC concrete, mesopores inhibit the movement of the chloride ion solution that passes through the surface and heads toward the interior. Furthermore, the retention effect of the capillary action of the mesopores prevents the chloride ion solution that has penetrated from the surface into the interior from moving into the pores located deeper.

[0098] This results in differences in the inhibitory effect on the penetration of chloride ion aqueous solution in OPC concrete, and the chloride ion concentration fluctuates greatly. Therefore, in areas where the distance from the surface of the OPC concrete is small, such as in range (b), the influence of chloride ions penetrating from the surface is greater, and it is thought that the fluctuations in chloride ion concentration will be greater. In addition, in range (c), it is thought that the chloride ions gradually decrease as a result of the combined effects of the supply of chloride ions by pores larger than macropores and the movement of chloride ions between pores, and the inhibition of the supply of chloride ions by mesopores and the suppression of the movement of chloride ions between pores.

[0099] (Consideration) Comparing the results of the immersion tests of IBPM concrete and OPC concrete from Figures 4 to 7 above, it is clear that the concentration of chloride ions penetrating deep into the concrete through the surface after immersion is 0.0 kg / m 3The distance from the surface where chloride ions penetrated was 10.8 mm for IBPM concrete, which was shorter than the distance from the surface where chloride ions penetrated. This means that IBPM concrete was more effective at inhibiting the penetration and migration of chloride ions than OPC concrete.

[0100] Compared to OPC concrete, IBPM concrete has fine mesopores as the pores that make up the voids in the areas where the fine and coarse aggregates have been removed from the hardened concrete. This makes it more resistant to chloride ions that penetrate through the surface from the outside and penetrate deeper into the concrete. In other words, by making the hardened concrete mainly mesopores, the concrete is made more dense, and it is possible to prevent chloride ions from migrating through the surface of the hardened concrete to the interior.

[0101] Furthermore, by densifying the area of ​​the hardened concrete excluding the fine and coarse aggregates, the pores that make up the voids in that area can be made into mesopores or pores smaller than mesopores, which makes it possible to inhibit the penetration of chloride ions in aqueous solutions from the surface of the hardened concrete and their migration deep into the hardened concrete. This reduces the occurrence of salt damage caused by chloride ions migrating with water through the surface of the hardened concrete to the interior. This makes it possible to improve the salt damage resistance of hardened concrete. [Example]

[0102] Next, as Example 2, the results of calculating the water penetration rate coefficient for IBPM concrete containing no cement are shown. The Japan Society of Civil Engineers' Standard Specifications for Concrete (Construction Edition) uses the moisture penetration rate coefficient to confirm the quality of concrete used in PCa products, and also suggests its application in evaluating the corrosion of rebar inside concrete. The IBPM concrete used in this example contains a large amount of industrial by-product admixture, making it susceptible to carbonation. However, due to the material's properties, the interior of the concrete is dense, which is presumably why water penetration is small and the impact of rebar corrosion is minimal. Therefore, in accordance with the Japan Society of Civil Engineers standard JSCE-G 582-2018, "Test Method for Water Penetration Rate Coefficients in Concrete Subjected to Short-Term Water Exposure," we compared the IBPM concrete with OPC concrete at design strengths of 30, 50, and 70 MPa to examine water penetration.

[0103] [Test Overview] (Example of materials used and concrete mix) The materials used in the composition for the cured product of this example are shown in Table 7 below.

[0104] [Table 7]

[0105] The composition of the hardened body according to this example is shown in Table 8 below. 3 An example of a suitable blend is shown below.

[0106] [Table 8]

[0107] In this example, crushed sand of hard sandstone type and crushed stone 2005 were used as aggregates. The binder for the IBPM concrete was a premix of ground granulated blast furnace slag (BFS), fly ash (FA), silica fume (SF), etc., similar to that used in Example 1. The slump flow value (SLF) and slump value (SL) were set to 50±7.5cm for the IBPM concrete and 6±2cm for the OPC concrete, and were adjusted with a high-performance water-reducing agent.

[0108] (Mixing method and curing method) The concrete was mixed using a forced biaxial mixer. The specimens were φ100 x 200 mm in diameter and packed in two layers, with each layer vibrated for 15 to 30 seconds using a table vibrator. After pouring, the concrete was steam cured under two conditions: an initial temperature of 20°C for 6 hours and an initial temperature of 20°C for 3 hours, after which the temperature was increased at a rate of 20°C / hour (h) to a maximum temperature of 65°C over a period of 4 hours. After steam curing, the specimens were removed from the mold and left to rest in a constant temperature room (20°C, RH 60%).

[0109] (Water penetration test) The test method complied with JSCE-G 582-2018. The specimens used for the moisture penetration test were cut 25 mm from the bottom in the circumferential direction, resulting in specimens 175 mm high. After curing in a constant temperature room for 91 days, it was confirmed that the mass change over 24 hours was 0.1% or less, and then they were used for the moisture penetration test.

[0110] The test specimens were sealed by applying aluminum foil tape to the cylindrical test specimens after they had dried, leaving a 25mm cut from the bottom and both sides of the poured surface. Nine test specimens were used for each mix, with three for immersion times of 5, 24, and 48 hours. After immersion, the test specimens were split open at the designated measurement time, sprayed with a water-sensitive developer (NDIS3423 compliant), and the distance that color developed was measured with a metal ruler. Measurements were taken at five points, 30mm from the side and every 10mm, to measure the water penetration distance from the test surface, and the average value was used.

[0111] (Test results) 8 and 9 show the relationship between the moisture penetration depth and the penetration time when the steam curing condition was a preliminary 6 hours. Figure 8 shows the results for the IBPM concrete of this example, and Figure 9 shows the results for the OPC concrete of the comparative example. In each figure, the horizontal axis represents immersion time (square root of time), and the vertical axis represents water immersion depth (mm). Each figure also shows the measurement results at 70 MPa, 50 MPa, and 30 MPa, as well as the regression equation and coefficient of determination.

[0112] In the relationship between the water penetration depth and the immersion time, the IBPM concrete according to the present example generally had a smaller water penetration depth than the OPC concrete according to the comparative example.

[0113] Next, the moisture penetration rate coefficient was calculated using the moisture penetration depth and the square root of the immersion time for 5, 24, and 48 hours, according to the formula described in JSCE-G582-2018.

[0114] Figure 10 shows the measurement results of water penetration depth at 30 MPa. (a) shows the results for the OPC concrete of the comparative example, and (b) shows the results for the IBPM concrete. When comparing the strength classes, the difference between the OPC concrete of the comparative example and the IBPM concrete of this example became significant, especially after 48 hours of immersion at 30 MPa.

[0115] Figure 11 shows the results of calculating the moisture penetration rate coefficient. The vertical axis shows the moisture penetration rate coefficient (mm / √h). The horizontal axis shows the moisture penetration rate coefficient values ​​at 70 MPa, 50 MPa, and 30 MPa for IBPM concrete when the steam curing conditions according to this example were a 6-hour pre-curing period, IBPM concrete when the steam curing conditions according to this example were a 3-hour pre-curing period, and OPC concrete when the steam curing conditions according to the comparative example were a 6-hour pre-curing period. Only at 30 MPa, values ​​calculated using the prediction formula of the Japan Society of Civil Engineers for OPC concrete and values ​​calculated using the prediction formula of the Japan Society of Civil Engineers for e-CON (registered trademark), an acid-resistant concrete according to Patent Document 1, are shown.

[0116] The moisture penetration rate coefficient of the IBPM concrete according to this example was 25%, 41%, and 29% of that of the OPC concrete according to the comparative example at 30, 50, and 70 MPa, respectively, and the strength of all of these concretes was lower than that of the OPC concrete. This is thought to be due to the properties of the binder in the IBPM concrete and the effect of the densification of the hardened body due to the low W / B ratio.

[0117] In a comparison between IBPM concrete with steam curing conditions of 3 hours and 6 hours, the one with 30 MPa and 3 hours of pre-curing had the highest moisture penetration rate coefficient. This was presumed to be due to the slow setting caused by the binder. For this reason, it is thought that an appropriate pre-curing time is necessary before steam curing.

[0118] In addition, the Japan Society of Civil Engineers' prediction formula, which is calculated from W / B, has an applicable range of 40-60%. When comparing the values ​​calculated at the applicable pressure of 30 MPa, both OPC concrete and IBPM concrete had values ​​smaller than the predicted value.

[0119] Table 9 below shows the approximate characteristic values ​​of the moisture penetration rate coefficients listed in the Japan Society of Civil Engineers' Standard Specifications for Concrete (Construction Edition).

[0120] [Table 9]

[0121] According to this, it was found that the moisture penetration rate coefficient of the IBPM concrete according to this embodiment is smaller than the characteristic value described in the Standard Specifications for Concrete (Construction Edition) of the Japan Society of Civil Engineers.

[0122] (summary) (1) The water penetration rate coefficient of IBPM concrete was about 25-41% of that of OPC concrete, and was smaller than that of OPC concrete at all design strengths. (2) The moisture penetration rate coefficient of IBPM concrete was smaller than the characteristic value described in the Standard Specifications for Concrete (Construction Edition) of the Japan Society of Civil Engineers.

[0123] It goes without saying that the configurations and operations of the above-described embodiments are merely examples, and can be modified as appropriate within the scope of the present invention.

Claims

1. The concrete mixture is made by blending water, a hydration reactive material, a latent hydraulic material, a pozzolanic reactive material, a hydroxide ion supplying material, an expansive material, a fine aggregate, a coarse aggregate, and a high-performance water reducing agent, The hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared in such a way that, in terms of particle size or specific surface area, the portion of the hardened body excluding the fine aggregate and coarse aggregate is filled with hardening reaction products that are generated and precipitated on the particle surfaces by the hardening reaction of the material particles, and are densified. A hardened body characterized by the above-mentioned.

2. The hydration-reactive material includes any one or any combination of portland cement, blast furnace cement, fly ash cement, calcium hydroxide, and a material that hardens by exhibiting a hydration reaction; the latent hydraulic material includes any one or any combination of ground granulated blast furnace slag, sewage sludge incineration ash, and a material that undergoes a hydraulic reaction and hardens in an alkaline atmosphere; The pozzolanic reactive material includes any one or any combination of fly ash, sewage sludge incineration ash, silica fume, fine volcanic glass powder for concrete, and a material that exhibits a pozzolanic reaction and hardens when stimulated by alkali, The hydroxide ion supplying material includes any one of potassium hydroxide, potassium carbonate, and slaked lime, or any combination thereof. The hardened body according to claim 1 .

3. The hydration reactive material, the latent hydraulic material, and the pozzolanic reactive material are The material is prepared so that the hardening reaction of a material with a large particle size or a small specific surface area begins later than that of a material with a small particle size or a large specific surface area. The hardened body according to claim 1 .

4. a hardening reaction product produced by hardening the hydration reactive material, the latent hydraulic material, and the pozzolanic reactive material fills voids present in a portion of the hardened body excluding the fine aggregate and the coarse aggregate, thereby densifying the portion; the hardened reaction product comprises calcium silicate, calcium hydroxide, calcium aluminosilicate hydrate, calcium silicate hydrate, hydrotalcite, ettringite, and monosulfate; The pores include gel pores, capillary pores, micropores, mesopores, and macropores. The hardened body according to claim 3 .

5. The hardening reaction products that are generated and precipitated on the surfaces of the material particles block the expanded bottom portions of the pores present in the portion of the hardened body excluding the fine aggregate and coarse aggregate, which is modeled as a cylindrical or conical shape, and are adjusted so as not to inhibit the movement of hardening reaction-required substances, which are present in the narrowed portions of the pores and are necessary for the hardening reaction of materials with small particle sizes or large specific surface areas, to the narrowed portions of the pores; The hardening reaction necessary materials include gel water, hydroxide ions, silicate compounds, and magnesium oxide. The hardened body according to claim 4 .

6. The pozzolan-reactive material, which takes a long time to initiate the hardening reaction, the latent hydraulic material, which initiates the hardening reaction quickly, and a hydration-reactive material are combined and blended so that the hardening reaction starts from a material with a small particle size or a large specific surface area to a material with a large particle size or a small specific surface area, Promoting the movement of the substance necessary for the curing reaction to the narrowed portion of the pore, Promoting the occurrence of a hardening reaction of a material having a small particle size or a large specific surface area present in the narrowed portion of the pore and in the vicinity of the narrowed portion of the pore, and promoting the generation and precipitation of the hardening reaction product on the surface of the material particle; The hardened body described in claim 5, characterized in that the hardening reaction product on the surface of the material particles fills pores that are modeled as cylindrical or conical and exist in the part of the hardened body excluding the fine aggregate and coarse aggregate, from the narrowed portion to the expanded portion.

7. A method for producing a concrete mixture comprising: mixing water, a hydration reactive material, a latent hydraulic material, a pozzolan reactive material, a hydroxide ion supplying material, an expansive material, a fine aggregate, a coarse aggregate, and a high-performance water reducing agent; The hydroxide ion supply material includes any one or any combination of potassium hydroxide, potassium carbonate, slaked lime, and hydroxide ion compound materials other than the hydroxide ion supply material. The hardened body according to claim 1 .

8. The concrete mixture is made by blending water, a hydration reactive material, a latent hydraulic material, a pozzolanic reactive material, a hydroxide ion supplying material, an expansive material, a fine aggregate, a coarse aggregate, and a high-performance water reducing agent, The hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared so that the particle size or specific surface area of ​​the hardened body, excluding the fine aggregate and coarse aggregate, is densified by the hardening reaction product that precipitates on the particle surface when the hardening reaction of the materials occurs. A composition for a cured body, characterized in that:

9. The concrete mixture is made by blending water, a hydration reactive material, a latent hydraulic material, a pozzolanic reactive material, a hydroxide ion supplying material, an expansive material, a fine aggregate, a coarse aggregate, and a high-performance water reducing agent, The hydration-reactive material, the latent hydraulic material, and the pozzolanic-reactive material are prepared in such a way that, in terms of particle size or specific surface area, the portion of the hardened body excluding the fine aggregate and coarse aggregate is filled with hardening reaction products that are generated and precipitated on the particle surfaces by the hardening reaction of the material particles, and are densified. A method for compounding a hardened product.

10. The hydration-reactive material includes any one or any combination of portland cement, blast furnace cement, fly ash cement, calcium hydroxide, and a material that hardens by exhibiting a hydration reaction; the latent hydraulic material includes any one or any combination of ground granulated blast furnace slag, sewage sludge incineration ash, and a material that undergoes a hydraulic reaction and hardens in an alkaline atmosphere; The pozzolanic reactive material includes any one or any combination of fly ash, sewage sludge incineration ash, silica fume, fine volcanic glass powder for concrete, and a material that exhibits a pozzolanic reaction and hardens when stimulated by alkali, The hydroxide ion supplying material includes any one of potassium hydroxide, potassium carbonate, and slaked lime, or any combination thereof.

10. A method for compounding a cured product according to claim 9.

11. The hardening reaction products that are generated and precipitated on the surfaces of the material particles are adjusted so as not to block the expanded bottom portions of the pores present in the cylindrical or conical modeled portions formed in the portions excluding the fine aggregate and coarse aggregate, thereby preventing the movement of hardening reaction-required substances, which are present in the narrowed portions of the pores and are necessary for the hardening reaction of materials with small particle sizes or large specific surface areas, from the narrowed portions of the pores. The hardening reaction necessary materials include gel water, hydroxide ions, silicate compounds, and magnesium oxide.

10. A method for compounding a cured product according to claim 9.

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