Activation method, carbon dioxide absorption method, cement composition manufacturing method, mortar composition manufacturing method, concrete manufacturing method, and precast concrete manufacturing method

Abstract

To provide a method of activating sewage sludge incineration ash so that a larger amount of the ash can be used as a material to be mixed in concrete.SOLUTION: The method of activating sewage sludge incineration ash comprises mixing water, sand, and a saturated calcium hydroxide solution with sewage sludge incineration ash and carrying out ball mill mixing using a rotary frame, in which: balls having a density higher than a specific density, for example, a density higher than a zirconia ball are used; a plurality of zirconia balls each having a different diameter are used; the rotation speed of the rotary frame is from 30 to 50 rpm; 25 to 200% of water, 40 to 80% of sand and 20 to 80% of the saturated calcium hydroxide solution relative to the mass of the sewage sludge incineration ash are mixed; and the ball mill mixing is carried out for a period of 1 to 5 hours.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates particularly to a method for activating sewage sludge incineration ash used in concrete production, a method for absorbing carbon dioxide, a method for producing a cement composition, a method for producing a mortar composition, a method for producing concrete, and a method for producing precast concrete. [Background technology]

[0002] Sewage sludge is the sludge that is generated in the sedimentation tanks and reaction tanks of a treatment plant during sewage treatment, and sewage sludge burnt ash (hereinafter abbreviated as "SSA") is the combustion ash obtained by incinerating sewage sludge to reduce its volume. In Japan, industrial waste is generated at a rate of approximately 380 million tons annually, with sewage sludge accounting for about 20% of that amount. The recycling rate for sewage sludge fell from 78% to 55% due to the Great East Japan Earthquake, but recovered to 73% in 2016. There are three main uses for recycled sewage sludge: (1) use in the cement sector, such as mortar compositions and concrete, including construction materials like bricks, cement, and alternative aggregates; (2) composting and using it as fertilizer in green farmland; and (3) use in the energy sector as solid fuel and digester gas. However, only a portion is being effectively utilized as a resource, and about 30% of sewage sludge is still disposed of in landfills. Therefore, a key technical challenge is to enhance the value of SSA as a resource, thereby promoting the expansion of its applications and increasing its usage volume.

[0003] Here, SSA has cement to As a material for this field, it has three advantages: (1) The Ca(OH)2 produced in the hydration reaction of cement undergoes a pozzolanic reaction with the silica component in SSA, potentially generating calcium silicate hydrate and increasing compressive strength; (2) there is little variation in its composition throughout the year; and (3) a stable supply is possible.

[0004] According to Patent Document 1, an acid-resistant concrete with a long service life that does not require coating is described, which is manufactured by blending water, industrial by-products, an alkaline stimulant, an expansive agent, fine aggregate, coarse aggregate, and a high-performance water-reducing agent. The acid-resistant concrete described in Patent Document 1 can also use SSA as industrial waste. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Patent Publication No. 2019 / 172349 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, unlike fly ash (FA), which is pulverized coal combustion ash, conventional SSA contains a large amount of phosphorus. Therefore, when conventional SSA is used in concrete production, the phosphorus component reacts with alite and belite, which are constituent compounds of cement, thus affecting the cement. to This was causing a setting delay phenomenon, which slowed down the hardening process. In addition, SSA has high water absorption due to its porous nature, unlike concrete. to This could negatively impact their workability. Therefore, there were quantitative limitations to using SSA as a concrete admixture, and there was a need for technology that would allow for its use in larger quantities.

[0007] This invention has been made in view of the above circumstances, and aims to resolve the aforementioned problems and provide a method for activating SSA that makes it possible to use SSA in larger quantities as a concrete admixture. [Means for solving the problem]

[0008] The present invention relates to a method for activating sewage sludge incineration ash, comprising mixing the sewage sludge incineration ash with water, sand, and a saturated calcium hydroxide solution. Density of 6.00 g / ml or higher This method is characterized by performing ball mill mixing using a rotating stand with balls. The activation method of the present invention is characterized in that the balls used are multiple balls of different diameters. The activation method of the present invention is characterized in that the rotation speed of the rotating frame is 30 rpm to 50 rpm, the amount of water is 25 to 200% of the mass of the sewage sludge incineration ash, the amount of sand is 40 to 80%, the amount of saturated calcium hydroxide solution is 20 to 80%, and the mixing time of the ball mill mixing is 0.3 to 2 hours. The activation method of the present invention is characterized by reducing the average particle size of the sewage sludge incineration ash to 5 μm or less by the ball mill mixing. The activation method of the present invention involves the ball mill mixing process, which produces a layered crystal This is characterized by the fact that the substance is attached to the surface of the particles. The carbon dioxide absorption method of the present invention is characterized by absorbing carbon dioxide extracted from the atmosphere and / or exhaust gas into the saturated calcium hydroxide solution according to the activation method and immobilizing it. The carbon dioxide absorption method of the present invention is characterized by further mixing any or any combination of blast furnace slag fine powder, fly ash, waste concrete crushed material, and concrete sludge. The carbon dioxide absorption method of the present invention involves adding water, sand, water, sand, water, sand, to any one or any combination of blast furnace slag fine powder, fly ash, waste concrete crushed material, and concrete sludge. saturation Mix the calcium hydroxide solution and perform ball mill mixing using a rotating stand. saturation This method is characterized by absorbing and immobilizing carbon dioxide extracted from the atmosphere and / or exhaust gases in a calcium hydroxide solution. The present invention relates to a method for producing a cement composition, characterized by incorporating the sewage sludge incineration ash activated by the activation method described above. The present invention relates to a method for producing a cement composition in which the activated sewage sludge incineration ash is used as cement toIt is characterized in that it is formulated so that the mass ratio is 5% to 25% and it is an internal substitution of sand. The method for producing a mortar composition according to the present invention is characterized in that a mortar composition is produced using the cement composition produced by the method for producing a cement composition. The method for producing concrete according to the present invention is a mixture of water, industrial by-products, an alkali stimulant, an expansion agent, fine aggregate, coarse aggregate, and a water reducing agent. The industrial by-products include fly ash, blast furnace slag fine powder, and silica fume Mu any one or any combination And, sewage sludge incineration ash and and the alkali stimulant includes slaked lime or calcium carbonate. The sewage sludge incineration ash is mixed with water, sand, and a saturated calcium hydroxide solution, Density of 6.00 g / ml or higher and ball mill mixing is performed using a ball on a rotating mount, and it is characterized in that it is activated. The method for producing precast concrete according to the present invention is characterized in that precast concrete is produced using the mortar composition produced by the method for producing a mortar composition or the concrete produced by the method for producing concrete.

Advantages of the Invention

[0009] According to the present invention, by mixing water, sand, and a saturated calcium hydroxide solution with SSA and performing ball mill mixing with a ball having a specific density or more, while inactivating the phosphorus component as calcium phosphate, the water absorption is improved by atomization and the workability is not adversely affected, an activation method of SSA that can activate SSA so that it can be used in large quantities in the cement field more than before can be provided.

Brief Description of the Drawings

[0011] The inventors of this invention decided to develop a technology to highly activate sewage sludge combustion ash (SSA) with the aim of increasing the compressive strength of mortar, reducing hardening delay, and improving water absorption, in order to promote the effective utilization of SSA.

[0012] Therefore, the inventors focused on a method of activating fly ash (hereinafter abbreviated as "FA"), which is pulverized coal combustion ash, by ball mill mixing. Based on this, they diligently conducted experiments and completed the method for activating SSA as a concrete admixture of the present invention. Specifically, as shown in the examples described later, SSA, water, sand, saturated calcium hydroxide solution, and ceramic balls were added to a wide-mouth reagent bottle and mixed using a ball mill on a rotating stand to improve the compressive strength development of the SSA. In particular, using zirconia balls as ceramic balls significantly improved the compressive strength development, and the activation effect of SSA, such as improved curing delay and suppression of decreased water absorption, was remarkable. In addition, the activation effect of SSA was also observed when stainless steel balls were used. In other words, by using zirconia balls with a density of approximately 6.00 g / ml, stainless steel balls with a density of approximately 7.9 g / ml, etc., as balls for ball mill mixing, it is possible to modify high-hardness SSA into a high-value-added concrete admixture. This makes it possible to incorporate activated SSA into the production of larger quantities of mortar compositions and concrete than before.

[0013] The following describes embodiments of the SSA activation method, the cement composition manufacturing method, the mortar composition manufacturing method, the concrete manufacturing method, and the precast concrete manufacturing method of the present invention.

[0014] [Methods for activating SSA] The activation method according to this embodiment is a method for activating SSA, characterized by mixing SSA with water, sand, and a saturated calcium hydroxide solution, and performing ball mill mixing using a rotating stand with balls of a specific density or higher.

[0015] The SSA according to this embodiment can be sewage sludge incineration ash obtained during ordinary sewage treatment, which may contain phosphorus. In this case, it is preferable to use SSA with an average particle size of about 10 to 15 μm. Furthermore, as the SSA in this embodiment, it is also possible to use "super ash," which is SSA with adjusted particle size, as described in Patent Document 1.

[0016] The water according to this embodiment is not particularly limited and may be tap water. The pH and other properties of the water according to this embodiment are also arbitrary.

[0017] The sand used in this embodiment can be standard sand, such as that used as fine aggregate in ordinary concrete. Specifically, for example, it can be sand that corresponds to JIS A 5005 Crushed Sand (Hard Sandstone) with a density of 2.62 g / cm³. 3 It is preferable to use materials of a certain quality. More specifically, it is possible to use JIS standard sand for mortar, silica sand, etc.

[0018] The saturated calcium hydroxide solution according to this embodiment is preferably prepared by dissolving, for example, slaked lime corresponding to JIS R 9001 Special Grade, i.e., calcium hydroxide (Ca(OH)2), in the aforementioned water to a saturated state. The density of the calcium hydroxide before dissolution is, for example, 2.30 g / cm³. 3 It is preferable that it be of a certain degree.

[0019] The ball mill mixing according to this embodiment is a mixing method in which the material and balls are placed in a container and rotated on a rotating stand to produce a fine powder (micronization). In this embodiment, ball milling is performed using balls with a density of a specific magnitude or higher. Specifically, zirconia (ZrO2) balls with a density of at least 6.00 g / ml are used as balls with a density of a specific magnitude or higher. Zirconia balls have a higher density than alumina ceramics (Al2O3, density 3.61 g / ml) and are ceramic spheres with the highest mechanical strength at room temperature. In addition, other ceramic spheres, stainless steel balls, etc., can also be used as balls with a density of a specific magnitude or higher according to this embodiment.

[0020] In this embodiment, it is preferable to use multiple balls of different diameters. Specifically, as shown in the examples described later, in the case of a 500 ml wide-mouth reagent bottle, for example, in the case of zirconia balls, it is preferable to include multiple balls with a diameter of 15 mm or more, specifically three or more balls. More specifically, it is preferable to use multiple balls of different diameters, as this will result in a greater activation effect. In the case of zirconia balls, as shown in the examples described later, it is more preferable to include 10 zirconia balls with a diameter of 15 mm and 5 zirconia balls with a diameter of 10 mm. Furthermore, when actually activating SSA, it is possible to scale up the configuration based on this 500ml wide-mouth reagent bottle.

[0021] More specifically, in the configuration of the ball mill mixing according to this embodiment, it is preferable that the rotation speed of the rotating stand be 30 rpm to 50 rpm, the amount of water be 25 to 200% of the mass of SSA, the amount of sand be 40 to 80%, the amount of saturated calcium hydroxide solution be 20 to 80%, and the mixing time of the ball mill mixing be 0.3 to 2 hours. Within this range, SSA can be sufficiently activated by adding high energy to it using balls of a specific density or higher to atomize it. Furthermore, as mentioned above, activation can be further enhanced by using multiple balls.

[0022] Furthermore, it is preferable to achieve an average particle size of 5 μm or less with the ball mill mixing according to this embodiment. Specifically, it is preferable to grind the SSA under the conditions described above or scaled-up conditions to reduce the apparent average particle size of the SSA particles to approximately 5 μm or less.

[0023] Furthermore, by ball mill mixing according to this embodiment, layered crystal It is preferable that the substance adheres to the surface of the particles. Specifically, during the crushing of SSA particles, it is possible to cause the phosphorus contained in the SSA to react with calcium hydroxide, thereby producing calcium phosphate crystals that suppress the setting delay phenomenon of concrete.

[0024] [Methods for absorbing carbon dioxide] In the above-described method for activating SSA, phosphorus contained in SSA is immobilized by reacting with a saturated calcium hydroxide solution. At this time, it is also possible to absorb and immobilize not only phosphorus but also carbon dioxide extracted from the atmosphere and / or exhaust gases into the saturated calcium hydroxide solution.

[0025] This carbon dioxide can be, for example, carbon dioxide absorbed or compressed from the atmosphere using an absorption and compression facility. Alternatively, uncompressible carbon dioxide present in the atmosphere at around 400 ppm may be used. Furthermore, carbon dioxide contained in the combustion exhaust gas of petroleum, coal, natural gas, etc., and / or waste incineration exhaust gas can also be used. Of these, the combustion exhaust gas can be the exhaust gas from a rotary kiln furnace used in cement production. Furthermore, the waste incineration exhaust gas can be the exhaust gas from the incineration of sewage sludge. In this case, the exhaust gas can be used for calcium carbonate production at the same time as obtaining the sewage sludge incineration ash mentioned above.

[0026] Furthermore, although the embodiments described above describe an example in which only SSA is activated, it is also possible to further mix in any combination of blast furnace slag powder, FA, crushed waste concrete, and concrete sludge. This concrete sludge is cement sludge (concrete sludge) discharged from centrifugal-formed concrete. Furthermore, it is also possible to use only blast furnace slag powder, FA, and waste concrete pulverized material without mixing in SSA. In this case, if only blast furnace slag powder, FA, and waste concrete pulverized material are used, and the hardness is relatively lower than that of SSA, it is also possible to use balls with a density below a certain level, such as alumina balls, as balls for ball mill mixing.

[0027] Here, FA in this embodiment is porazon coal ash (fly ash) for concrete, collected by a dust collector during the combustion of pulverized coal at a thermal power plant. FA in this embodiment is, for example, fly ash type II or a similar product as defined in JIS A 6201, with a density of 2.20 g / cm³. 3 It is preferable that it be of a certain degree.

[0028] Furthermore, the blast furnace slag fine powder according to this embodiment is a fine powder produced as a by-product in the pig iron manufacturing process. This blast furnace slag fine powder is preferably, for example, one with a specific surface area of ​​4000 fineness as specified in JIS A 6206. It also has a density of 2.91 g / cm³. 3 It is preferable that it be of a certain degree.

[0029] In addition, the aforementioned concrete sludge can be used as a substitute for, or in addition to, a saturated calcium hydroxide solution. This makes it possible to generate calcium carbonate and use it as an aggregate that absorbs carbon dioxide.

[0030] In summary, the carbon dioxide absorption method according to this embodiment is characterized by mixing water, sand, and a calcium hydroxide solution with any combination of SSA, blast furnace slag powder, FA, and waste concrete pulverized material as industrial waste, mixing with a ball mill using a rotating stand, and allowing the calcium hydroxide solution to absorb and fix carbon dioxide extracted from the atmosphere and / or exhaust gas, wherein the calcium hydroxide solution is a saturated calcium hydroxide solution and / or concrete sludge. In this case, it is preferable to use zirconia balls if the industrial waste contains SSA, and alumina balls or zirconia balls if it does not contain SSA.

[0031] [Method for manufacturing cement composition] The cement composition manufacturing method according to this embodiment is characterized by incorporating SSA activated by the activation method described above, and / or industrial waste that has absorbed carbon dioxide by the carbon dioxide absorption method described above. More specifically, when manufacturing the mortar composition according to this embodiment, it is also possible to prepare a premix or mixture (hereinafter simply referred to as "cement composition") containing cement or other admixtures, using the activated SSA and / or carbon dioxide-absorbing industrial waste mentioned above as admixtures.

[0032] In this embodiment, the cement can be ordinary Portland cement, blast furnace cement, fly ash cement, silica cement, or a mixture thereof. Of these, the ordinary Portland cement may be various types of Portland cement possessing properties such as moderate heat, low heat, rapid strength, ultra-rapid strength, and sulfate resistance. Furthermore, ordinary Portland cement, for example, has a density of 3.15 g / cm³ as specified in JIS R 5210, etc. 3 degree, specific surface area 3310cm 2 You may also use something around / g.

[0033] Alternatively, it is possible to prepare a cement composition that includes a concrete composition that does not use Portland cement, such as the concrete described in Patent Document 1.

[0034] Here, in the cement composition according to this embodiment, the industrial waste that has absorbed activated SSA and / or carbon dioxide is cement to It is preferable that the mixture be formulated in a mass ratio of 5% to 25% so that it replaces the sand (fine aggregate) within the mixture. In the case of the above-mentioned configuration that does not use Portland cement, it is possible to use a larger amount than that of SSA described in Patent Document 1.

[0035] Furthermore, the cement composition according to this embodiment may also be provided in a form that includes fine aggregate and / or any combination thereof. In this case, the mixing ratio and other parameters may be changed depending on whether it is precast or cast in place.

[0036] [Mortar composition and concrete manufacturing method] It is possible to manufacture a mortar composition or concrete using the cement composition manufactured by the cement composition manufacturing method according to this embodiment. Specifically, a mortar composition or concrete can be produced by adding water, fine aggregate, and other admixtures to the cement composition according to this embodiment, or by adding coarse aggregate as well, mixing, molding, and curing.

[0037] In this embodiment, the fine aggregate can be crushed sand (sand) and calcium carbonate. This sand can be the same type of sand used for the SSA activation described above, or other types of sand used in the cement industry. Furthermore, environmentally friendly calcium carbonate may be used, which is manufactured using carbon dioxide extracted from the atmosphere and / or exhaust gases as a raw material. In this case, it is also possible to use calcium carbonate obtained by reacting calcium hydroxide solution and / or concrete sludge with carbon dioxide using the carbon dioxide absorption method described above.

[0038] In this embodiment, the concrete may also contain activated SSA and / or industrial waste that has absorbed carbon dioxide. In this case, as a concrete that does not use Portland cement, it is also possible to use a structure that hardens using geopolymers, pozzolanic reactions, or latent hydraulics.

[0039] Here, when hardening concrete using the pozzolanic reaction or latent hydraulics, it is preferable to mix an alkaline stimulant with FA and blast furnace slag fine powder. Since FA's main components are silica and alumina, it can be hardened by the pozzolanic reaction, which generates calcium silicate hydrate and the like when an alkaline stimulant is used. Blast furnace slag fine powder can also be hardened by "latent hydraulics," which generates calcium silicate hydrate and calcium aluminate hydrate when an alkaline stimulant is used.

[0040] In this embodiment, the alkali stimulant preferably contains calcium carbonate (slaked lime) similar to that produced by the carbon dioxide absorption method described above. This alkali stimulant makes it possible to harden FA and blast furnace slag fine powder without using any conventional Portland cement. It is also possible to use calcium carbonate as the alkali stimulant to replace sand as fine aggregate.

[0041] Furthermore, as the fine aggregate in this embodiment, slag-based aggregates such as fine aggregate produced from granulated blast furnace slag, electric furnace oxidized slag aggregate, and silica fume can also be used.

[0042] In this embodiment, the silica fume is mostly amorphous, spherical silica (SiO2) collected as dust in the exhaust gas from an arc-type electric furnace. This silica fume has a density of 2.30 g / cm³ as specified in JIS A 6207. 3 It is preferable to use materials of a certain degree. Silica fume is preferably used for densification and strength improvement.

[0043] Furthermore, the coarse aggregate in this embodiment can be a general type of coarse aggregate such as sandstone. This coarse aggregate, for example, corresponds to JIS A 5005 Crushed Stone 2005 (Hard Sandstone) and has a density of 2.67 g / cm³. 3 It is preferable that it be of a certain degree.

[0044] In addition, in the production of the mortar composition or concrete of this embodiment, it is possible to appropriately incorporate fibers, water-reducing agents, high-performance water-reducing agents, fluidizers, retarders, waterproof admixtures, moisture-proof admixtures, foaming agents, thickeners, antifreeze agents, colorants, workability enhancers, antiseptics, defoaming agents, setting regulators, shrinkage reducers, cement hardening agents, polymer emulsions, and the like.

[0045] The concrete according to this embodiment may be manufactured by compacting with centrifugal force, by vibration molding, or by casting during on-site construction.

[0046] [Precast concrete] The concrete according to this embodiment can be used in the manufacture of precast concrete. This precast concrete is particularly suitable for use in products requiring high strength. In this case, by setting the optimal composition and strength when manufacturing concrete products in a dedicated factory, manufacturing efficiency can be increased and manufacturing costs can be optimized.

[0047] Here, the concrete according to this embodiment may be compacted by centrifugal molding. In this centrifugal molding, a mixture of water, cement composition, expansive agent, fine aggregate, coarse aggregate, and water-reducing agent (hereinafter simply referred to as "mixture") mixed in the above proportions is filled into a centrifugal molding mold, the mold is rotated at high speed on a molding machine, and the concrete is compacted using centrifugal force to an acceleration of approximately 30 to 50 G, and excess water is discharged as sludge water (concrete sludge). At this time, the acceleration may be increased in several stages to ensure that the excess water is properly drained and the concrete is compacted densely. For example, in these stages, the concrete may be compacted at 5 G, 15 G, and 35 G at rates of 1 minute, 1 minute, and 7 minutes, respectively. By manufacturing the concrete according to this embodiment by centrifugal molding in this way, it is possible to increase the strength, further shorten the steam curing time, and manufacture high-performance cylindrical structures, etc. Furthermore, it is also possible to add carbon dioxide to this concrete sludge and use it for the production of the calcium carbonate mentioned above.

[0048] Furthermore, the concrete of this embodiment can be used not only as precast concrete formed by centrifugal molding as described above, but also as precast concrete formed by vibration. Examples of products that can be manufactured using vibration molding include box culverts and manholes. All of these products can be manufactured using the same manufacturing method as precast concrete such as Hume pipes. In other words, they can be manufactured simply by changing centrifugal molding to vibration molding. Therefore, the mixture of this embodiment can also be applied to the manufacture of vibration-formed precast concrete products.

[0049] With proper curing methods and sufficient temperature control, it is possible to use the mixture of this embodiment for on-site concrete placement.

[0050] In this embodiment, the required performance of the concrete may differ depending on the product to which it is applied. In this case, the issue can be addressed simply by fine-tuning the ratio of water (W) to total powder content (P) in the mixture (W / P), which corresponds to the ratio of water (W) to cement (C) (W / C) in concrete. Alternatively, instead of W / P, the water (W) to binder (B) ratio (hereinafter referred to as "W / B") can be used for adjustment. In this embodiment, W / B can be decreased or increased within a range that satisfies the required strength and fluidity performance.

[0051] Furthermore, by appropriately adjusting the fine aggregate ratio (s / a) and the amount of admixtures (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 which it is applied. Furthermore, the concrete according to this embodiment may be cured under high pressure and high temperature after molding.

[0052] By configuring it as described above, the following effects can be obtained. Conventionally, when SSA is used in mortar compositions or concrete manufacturing, (1) the phosphorus component reacts with alite and belite, which are constituent compounds of cement, to (2) It causes a setting delay phenomenon that slows down the hardening of concrete, and because it is porous, it has high water absorption, to There was a problem in that it could negatively affect the workability. For this reason, SSA could not be used in large quantities in mortar compositions or concrete manufacturing.

[0053] In contrast, by using these zirconia balls to ball-mill the SSA, in this embodiment, the SSA is made into fine particles, (1) the phosphorus contained in the SSA reacts with calcium hydroxide to inactivate it as calcium phosphate, (2) the surface area of ​​the SSA increases, improving reactivity, reducing water absorption, and (3) increasing mechanical strength. This suppresses the setting delay phenomenon during the manufacturing of mortar compositions and concrete, prevents impact on workability, increases compressive strength, and enables early strength enhancement. As a result, SSA can be used in large quantities as a concrete admixture.

[0054] Specifically, as shown in the examples described later, in SSA, phosphorus components not contained in FA were converted into insoluble calcium phosphate, and an improvement in setting delay of about 40 minutes was confirmed. Furthermore, the compressive strength of a mixed cement mortar containing activated SSA at 20% by mass of cement was 19.1% higher than that of a mixed cement mortar containing untreated SSA after 7 days of underwater curing. In addition, experiments were conducted to determine whether the compressive strength could be increased after several days had elapsed since the activation of SSA. Even after 28 days, no decrease in compressive strength was observed, and it was higher than that of standard JIS mortar. Furthermore, when the duration of the activation effect of the SSA-containing slurry after ball mill mixing was investigated, it showed higher compressive strength than JIS mortar during a 28-day static period. Furthermore, preliminary experiments by the inventors have shown that by adding a dispersant, the time constraints after activation treatment are reduced, and the activation can be maintained for several months. Therefore, even if prepared in advance, the activated SSA can maintain its quality as a mismixture for a long period of time.

[0055] In the concrete according to this embodiment, the addition of calcium hydroxide (Ca) is expected to enhance the hardening activity. Furthermore, by adding calcium carbonate manufactured using carbon dioxide appropriately extracted from the atmosphere and / or exhaust gases as a raw material, it becomes possible to reduce carbon dioxide emissions during concrete production.

[0056] Furthermore, the concrete according to this embodiment can be used for purposes other than precast concrete. For example, the concrete according to the present embodiment can also be used in ordinary construction, various production and manufacturing facilities, etc.

[0057] Next, the present invention will be further described with reference to the drawings by way of examples, but the following specific examples do not limit the present invention.

Example

[0058] 〔Activation possibility of SSA〕 In order to determine whether the high-activation treatment by the ball mill mixing method is effective or not with SSA, the compressive strength enhancement rate of the activated SSA-added mortar was compared under the optimum mixing conditions. Thus, the activation of SSA was investigated. In addition, in order to examine the influence of the material and diameter of the ceramic balls, a comparison of the compressive strength enhancement rates of the activated SSA- and FA-added mortars with the change in the composition of the ceramic balls (hereinafter also referred to as "balls") was carried out.

[0059] (Materials used) The materials used were ordinary Portland cement (C: density 3.16 g·cm -3 ), sewage sludge incineration ash (SSA: density 2.60 g·cm -3 , BET specific surface area 3.78 m 2 ·g -1 ), fly ash type II (FA: density 2.23 g·cm -3 , Blaine specific surface area 4650 cm 2 ·g -1 ), tap water (W), standard sand (S: for the strength test of the Cement to Association), saturated calcium hydroxide solution (SSAt.Ca(OH)2), manufactured by Kanto Chemical Co., Ltd., and dissolved in special grade). The chemical compositions of the SSA and FA used in this example are shown in Table 1 below. The unit is mass%.

[0060] <>

Table 1

[0061] (Experimental procedure) Figure 1 illustrates the experimental procedure. First, powder containing SSA or FA was placed in a 500 ml wide-mouth reagent bottle and mixed with a ball mill. Then, it was mixed in a mortar mixer, molded using a 4-4-16 mold, and pre-cured. After that, it was demolded, cured in water (water temperature 20°C), and a compression test was performed. The following describes the details of those processes.

[0062] First, for ball mill mixing, 25% by mass of ordinary Portland cement was replaced with SSA or FA (either SSA or FA will be simply referred to as "admixture" below) in accordance with JIS A 6201, and SSA was similarly replaced for comparison. The ball mill mixing procedure involved adding SSA or FA, saturated calcium hydroxide solution, water, standard sand, and ceramic balls to a wide-mouth reagent bottle (73 mm outer diameter, 168 mm length, 500 ml capacity, made of low-density polyethylene), and mixing was performed using a two-stage ball mill rotating stand. The ceramic spheres are made of alumina balls (density 3.61 g·cm³), which have high wear resistance and can move freely within the reagent bottle. -3 ), and zirconia balls (density 6.00 g·cm³) -3 ) was used. The composition of these ceramic spheres is shown in Table 2 below.

[0063] [Table 2]

[0064] The ball mill mixing conditions other than the ball composition were based on the conventional optimal mixing method for factory automation and were as follows: (1) Rotation speed of the rotating stand was 30 rpm, (2) Mixing time was 1 hour, (3) Saturated calcium hydroxide solution amount was 50% of the mass of the admixture, (4) Water amount was 62%, and (5) Sand amount was 44%. The formulation and ball mill mixing conditions for ball mill mixing (Admixture) are shown in Table 3 below.

[0065] [Table 3]

[0066] The specimens were prepared in accordance with JIS R 5201. A JIS mortar mixer was used for mixing, and a 40 x 40 x 160 mm rectangular prism mold was used. After molding the specimens, they were pre-cured for 24 hours in a constant temperature chamber at 20°C. After that, they were demolded and cured in water at 20°C for 28 days. Mortar with activated admixture added (hereinafter referred to as "mortar with activated admixture") was prepared by adding cement, the remaining water and standard sand to the slurry containing the admixture after the ball mill mixing described above, and mixing. The mix design for the mortar with admixtures is shown in Table 4 below.

[0067] [Table 4]

[0068] The compression test was conducted in accordance with JIS R 5201. Six specimens were measured at a time, and the average was used as the measured value.

[0069] (Results and Discussion) Figure 2 shows the compressive strength of FA-added mortar, and Figure 3 shows the compressive strength of SSA-added mortar. The test specimen numbers were assigned as follows: JIS mortar containing only cement was designated "JIS," untreated FA or SSA-added mortar was designated (0), and activated admixture-added mortar mixed using a ball mill according to the ball mix designation in Table 2 was designated (1) to (8). As mentioned above, the age was 28 days, and the curing method was underwater. According to the results in Figures 2 and 3, the activated FA-added mortar showed increased compressive strength compared to untreated FA-added mortar. The greatest increase in compressive strength was observed in (4), a ball mixture of 10 x 15mm and 5 x 13mm alumina balls, with a compressive strength increase rate of 18.3%. Furthermore, activated SSA-added mortar showed increased compressive strength in some ball formulations compared to untreated SSA-added mortar. The greatest increase in compressive strength was observed in (6), a ball formulation consisting of 10 zirconia balls of 15 mm and 5 zirconia balls of 10 mm, with a compressive strength increase rate of 4.6%.

[0070] Figures 2 and 3 show that the compressive strength enhancement rate of the activated SSA-added mortar was improved, indicating that, similar to FA, highly activated treatment by the ball mill mixing method is effective for SSA. Furthermore, compared to FA, SSA showed a smaller increase in compressive strength, and in some cases, even a decrease in compressive strength. This is likely due to differences in the pozzolanic reactivity of each admixture, as well as the fact that ball mill mixing was performed under the optimal mixing conditions for FA. Therefore, it is considered necessary to explore mixing conditions suitable for SSA.

[0071] Furthermore, while FA showed improved compressive strength enhancement in all ball formulations, SSA showed improvement only in some ball formulations. From this, it can be concluded that in the activation of admixtures by the ball milling method, FA is less affected by the ball formulation and can be activated with a variety of ball formulations. In contrast, with SSA, the ball composition, i.e., the ball material, ball diameter, and combination, were considered to have a significant impact. In ball mill mixing of SSA, a combination of zirconia balls with multiple balls of 15 mm or larger in diameter showed an increase in compressive strength. From this, it is thought that a larger ball weight, i.e., more energy, is required for high activation of SSA compared to FA.

[0072] Furthermore, regarding the optimal ball combination in the ball mill mixing method, both SSA and FA tended to be more activated with ball combinations of multiple balls, including multiple balls of the same diameter, compared to ball combinations of a single ball diameter. In other words, a combination of multiple ball diameters, including multiple balls of the same diameter, was preferred. This is because, compared to a single ball combination, the admixture particles are finely ground and subdivided, which is thought to improve the reactivity with the added saturated calcium hydroxide solution and thus activate the mixture. In addition, combining multiple balls of the same diameter increases the grinding efficiency. This reduces uneven mixing, which is thought to result in higher activation. The common characteristic of samples (1), (3), (4), (5), and (7), which showed reduced compressive strength, was that they contained three or fewer zirconia balls larger than 15 mm. Therefore, it is thought that sufficient crushing was not achieved, leading to aggregation, which reduced the surface area and resulted in lower compressive strength compared to untreated SSA-added mortar. Thus, high activation by the ball mill mixing method is also effective for SSA. The optimal ball composition for high activation of SSA is a mixture of multiple zirconia balls, each 15 mm or larger in diameter. In this example, the optimal composition was zirconia balls, consisting of 10 balls with a diameter of 15 mm and 5 balls with a diameter of 10 mm. In this embodiment, ball mill mixing was performed using multiple zirconia balls as described above. However, while ball mill mixing is preferable in SSA using balls of a material with a specific density (specific gravity) or higher, it is believed that it may also be possible with a single ball depending on conditions such as ball density, size, grinding time, and vibration frequency.

[0073] [Searching for optimal mixing conditions] Based on the experimental results described above, the ball mill mixing conditions for SSA were optimized to further improve the rate of increase in compressive strength. The optimal mixing conditions were investigated for four experimental parameters of the ball mill mixing method: solid-liquid ratio, water volume, sand volume, and rotation speed. Furthermore, in this experiment, SSA was used as an external replacement for standard sand to compare its compressive strength with that of JIS mortar.

[0074] (Materials used) The materials used are ordinary Boltland cement (C: density 3.16 g·cm³). -3 ), SSA (density 2.60g cm -3 , BET specific surface area 3.78m 2 ·g -1 The materials used were tap water (W), standard sand (CS: for cement strength testing by the Cement Association), and saturated calcium hydroxide solution (manufactured by Kanto Chemical, special grade dissolved). The same SSA used was used as described above.

[0075] (Experimental procedure) SSA is cement to Standard sand was replaced with SSA at a mass ratio of 10%. The following ranges were investigated for the ball mill mixing conditions: (1) Rotation speed of the rotating stand was 30 rpm to 40 rpm, (2) saturated calcium hydroxide solution amount was 20 to 100% of the mass of SSA, (3) water amount was 25 to 200%, and (4) sand amount was 0 to 100%. Other conditions included a ball composition of 10 zirconia balls of 15 mm and 5 of 10 mm, a mixing time of 1 hour, and mixing using a 500 ml wide-mouth reagent bottle. Specimens were prepared using the same procedure as described above, and after demolding, they were cured in water for 7 days. Compression strength tests were also performed using the same procedure as described above, and the SSA mixing conditions were optimized based on the test results.

[0076] (result) Figures 4(a) to 4(f) show the results of this search for optimization conditions. Figure 4(a) shows the intensity peak for sand quantity, Figure 4(b) for rotation speed, Figure 4(c) for ball count, Figure 4(d) for water quantity, Figure 4(e) for mixing time, and Figure 4(f) for calcium hydroxide quantity. For both the FA and SSA series, the optimal conditions are marked with a circle. In addition, although the calcium hydroxide quantity in Figure 4(f) is shown as "0.03g~0.83g", this indicates that it is approximately 20%~500% of the mass of SSA.

[0077] Thus, by comparing the compressive strength enhancement rates of SSA-added mortars and optimizing the combinations of sand content, rotation speed, water content, and solid-liquid ratio through trial and error, the results are as follows: (a) The optimal sand amount was 60%, and (b) the optimal rotation speed of the rotating stand was 40 rpm. Also, (c) the ball composition was 10 zirconia balls of 15 mm and 5 of 10 mm, (d) the optimal water amount was 180%, (e) the optimal mixing time was 1 hour, and the optimal wide-mouth reagent bottle capacity was 500 ml. Furthermore, (f) the optimal amount of saturated calcium hydroxide solution relative to the mass of SSA was 40% (0.06 g in Figure 4(f)). These were defined as the optimal ball mill mixing conditions for SSA, and the following experiment was conducted.

[0078] [Morphological observation of SSA after mixing with Pallmill] To confirm the changes that occur in SSA particles due to ball mill mixing, morphological observation of SSA was performed using a scanning electron microscope.

[0079] (Experimental method) A sample of SSA slurry after ball mill mixing was collected, air-dried in a room at 20°C, and then D-dryed. The morphology of the activated SSA after ball mill mixing was observed. Morphological observation was also performed on untreated SSA to compare the changes in SSA particles due to ball mill mixing. A scanning electron microscope (SEM SU5000, Hitachi High-Tech Corporation) was used for observation. Pt+Pd deposition was performed before observation. Ball mill mixing was performed under the optimal mixing conditions described above.

[0080] (Results and Discussion) Figure 5 shows images observed by SEM. Figure 5(a) shows untreated SSA, and Figure 5(b) shows activated SSA ball-milled under optimal mixing conditions. Ball milling revealed that the SSA particles were pulverized, and their particle size decreased from approximately 10-15 μm to approximately 5 μm or less. Furthermore, Figure 5(b) shows layered structures that were not observed in Figure 5(a). crystalWe also observed that it was adhering to the surface of the particles. This was presumed to be due to the phosphorus component of SSA reacting with calcium hydroxide and changing into calcium phosphate.

[0081] Based on the above, it was concluded that the ball mill mixing method achieves high activation of SSA by: (1) increasing the surface area due to the pulverization of SSA particles; (2) reducing the setting delay effect as the phosphorus component of SSA reacts with calcium hydroxide to form calcium phosphate; and (3) eliminating the need to consider the water absorption of SSA by forming it into a slurry, i.e., reducing its water absorption. Of these, (1) to (3) are properties known to those skilled in the art as disadvantages of SSA, as described above, and it has been shown that these can be improved by the processing in this embodiment.

[0082] [Comparison of compressive strength] Ball mill mixing activated SSA-added mortar, untreated SSA-added mortar, cement to To compare the rate of increase in compressive strength of JIS mortar at different ages, the ages were set to 3, 7, 14, and 28 days. In addition, the same comparison was made when the SSA addition rate was varied, and the characteristics of the change in compressive strength were investigated.

[0083] (Experimental method) The materials used were the same as those described above. The addition rate of SSA was cement to The mass ratios were set to 5%, 10%, and 20%, and each was used as an external replacement for standard sand. Ball mill mixing was performed under the optimal mixing conditions described above. Specimens were prepared using the same procedure as described above, and after demolding, they were cured in water for the specified age periods of 3, 7, 14, and 28 days. The ball mill mixing conditions are shown in Table 5 below, and the SSA-added mortar mix design is shown in Table 6 below.

[0084] [Table 5]

[0085] [Table 6]

[0086] The compressive strength test was performed using the same procedure as described above.

[0087] (Results and Discussion) Figure 6 shows the results of compressive strength tests for activated SSA-added mortar at different additive rates. Furthermore, Table 7 below shows the compressive strength increase rate for each mix, based on the compressive strength of JIS mortar at 3 days of age.

[0088] [Table 7]

[0089] Figure 6 and Table 7 show that, regardless of whether or not SSA is activated, the addition of SSA results in a higher compressive strength than JIS mortar without SSA, and a trend was observed where the difference in compressive strength increase between untreated and activated SSA increased as the SSA addition rate increased. Furthermore, the compressive strength of wood with a 20% activated SSA additive rate was 19.1% higher at 7 days of age compared to untreated wood, and 6.4% higher at 28 days of age. Similar results were obtained with other additive rates, and the difference in compressive strength increase compared to untreated wood tended to decrease with longer ages. These results suggest that the ball milling process improved the compressive strength enhancement rate of SSA. This is because, during ball milling, the phosphorus component of SSA reacts with the saturated calcium hydroxide solution to form insoluble calcium phosphate, reducing the setting delay effect. As a result, the compressive strength enhancement rate due to the earlier hydration reaction increases compared to the untreated material. Additionally, the increased surface area due to grinding promotes hydration reactivity, leading to an increased compressive strength enhancement rate at earlier ages. Furthermore, the hydration reactivity here is considered to be a pozzolanic reaction, given that the composition of SSA contains substandard silica. saturation Calcium hydroxide solution Cement toThis may be increasing the hydration reaction rate.

[0090] [Time-dependent activation ability] With the aim of developing future applications for SSA slurry, we investigated the duration of SSA activation ability using the ball mill mixing method and estimated the shelf life of SSA slurry. In this experiment, the standing period of activated SSA slurry was set to 7, 14, 21, and 28 days, and the time dependence of activation ability was investigated by comparing the compressive strength of the SSA-added mortar.

[0091] (Experimental method) The materials used were the same as described above. The SSA addition rate was 10% by mass ratio to cement, and it was used as an external replacement for standard sand. Ball mill mixing was performed under the optimal mixing conditions described above. The wide-mouth reagent bottle after mixing was left to stand in a constant temperature room at 20°C, and the SSA slurry that had stood for the specified period was used as cement. to The mixture was then kneaded with water and standard sand. Specimens were prepared using the same procedure as described above for each test, and after demolding, they were cured in water for 7 days. The mix of the SSA-added mortar was the same as in Table 6 above. The compressive strength test was also performed using the same procedure as described above.

[0092] (Results and Discussion) Figure 7 shows the results of the compression test. The degree of activation tended to decrease slightly as the number of standing days increased. Furthermore, the activated SSA-added mortar showed higher compressive strength than the JIS mortar at all standing time intervals. Furthermore, in this embodiment, the decrease in compressive strength showed a decreasing trend after 28 days of standing. This is thought to be because the SSA particles, which were subdivided by pulverization, aggregated as the standing period lengthened, reducing their surface area and thus decreasing their reactivity. For this reason, preliminary experiments confirmed that by adding a dispersant, the time constraint could be extended, and the quality could be maintained for several months.

[0093] 〔summary〕 The findings obtained from this embodiment are shown below. (a) High activation by ball mill mixing is also effective in SSA. (b) SEM images show that the SSA particles were pulverized by ball milling and broken down to approximately 5 μm. (c) The rate of increase in compressive strength increased as the SSA addition rate increased, and under the optimal mixing conditions for SSA, no decrease in compressive strength was observed even at an addition rate of 20%. (d) We confirmed that ball mill mixing improved the rate of increase in compressive strength of SSA-added mortar at an early age. (e) The activation ability of the SSA slurry produced by the ball mill mixing method tended to decrease slightly over time. Furthermore, there was a risk of a rapid decrease after 28 days, so it was preferable to use it within about 14 days after mixing. (f) The ball mill mixing method was able to improve upon the disadvantages of SSA, namely the delayed setting phenomenon and high water absorption.

[0094] It goes without saying that the configuration and operation of the above embodiment are examples and can be modified as appropriate without departing from the spirit of the present invention.

Claims

1. A method for activating sewage sludge incineration ash, The aforementioned sewage sludge incineration ash is mixed with water, sand, and a saturated calcium hydroxide solution. Ball mill mixing is performed using a rotating stand with balls having a density of 6.00 g / ml or higher. A method for activation characterized by the following features.

2. The aforementioned balls are made up of multiple balls of different diameters. The activation method according to feature 1.

3. The rotational speed of the aforementioned rotating frame is 30 rpm to 50 rpm. With respect to the mass of the sewage sludge incineration ash, the amount of water is 25 to 200%, the amount of sand is 40 to 80%, and the amount of saturated calcium hydroxide solution is 20 to 80%. The mixing time for the ball mill mixing described above is set to 0.3 to 2 hours. The activation method according to feature 1.

4. The ball mill mixing process reduces the average particle size of the sewage sludge incineration ash to 5 μm or less. The activation method according to feature 1.

5. The ball milling process results in a state where layered crystals are attached to the surface of the particles. The activation method according to feature 1.

6. The saturated calcium hydroxide solution according to the activation method described in any one of claims 1 to 5 absorbs and immobilizes carbon dioxide extracted from the atmosphere and / or exhaust gas. A method for absorbing carbon dioxide, characterized by the features described above.

7. Further mix in any or any combination of blast furnace slag powder, fly ash, waste concrete pulverized material, and concrete sludge. The carbon dioxide absorption method according to feature 6.

8. Mix any or any combination of blast furnace slag powder, fly ash, waste concrete crushed material, and concrete sludge with water, sand, and saturated calcium hydroxide solution. Ball mill mixing is performed using a rotating stand. The saturated calcium hydroxide solution absorbs and fixes carbon dioxide extracted from the atmosphere and / or exhaust gas. A method for absorbing carbon dioxide, characterized by the features described above.

9. The sewage sludge incineration ash, activated by the activation method described in any one of claims 1 to 5, is blended. A method for producing a cement composition characterized by the following features.

10. The activated sewage sludge incineration ash is mixed in such a way that it replaces the sand in the cement at a mass ratio of 5% to 25%. The method for producing a cement composition according to feature 9.

11. A mortar composition is manufactured using the cement composition produced by the cement composition manufacturing method described in claim 9. A method for producing a mortar composition characterized by the following features.

12. It is a mixture of water, industrial by-products, alkaline stimulants, expanding agents, fine aggregates, coarse aggregates, and water-reducing agents. The aforementioned industrial by-products include fly ash, blast furnace slag powder, and silica fume, or any combination thereof, and sewage sludge incineration ash. The aforementioned alkaline stimulant contains slaked lime or calcium carbonate, The aforementioned sewage sludge incineration ash is activated by mixing it with water, sand, and saturated calcium hydroxide solution, and then mixing it in a ball mill using a rotating stand with balls having a density of 6.00 g / ml or more. A concrete manufacturing method characterized by the following features.

13. Precast concrete is manufactured using a mortar composition produced by the mortar composition manufacturing method described in claim 11, or concrete produced by the concrete manufacturing method described in claim 12. A method for manufacturing precast concrete characterized by the following features.

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