JP2008087468A - Method for manufacturing coal ash slurry for cement based composition and cement based composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a coal ash slurry for a cement based composition which method can be employed for making a coal ash into a condition in which it can be used effectively as a material for manufacturing a cement based composition, and to provide a cement based composition containing a coal ash manufactured by the manufacturing method. <P>SOLUTION: Raw material coal ash generated in a thermoelectric power plant etc. is supplied to a mixing tank 10 of a mixer 1 with water. A mixer 1 includes a screw-like mixing impellers 13 and 14 and a wing plate 15 inside a mixing tank 10, and has a configuration in which these revolve with a rotary shaft 12 with the activation of a motor 16. When a mixer 1 is operated over a prescribed time in a condition that a raw material coal ash and water are supplied into a mixing tank 10, a coal ash slurry in which a coal ash atomized is dispersed in water is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a coal ash slurry for a cement composition, and a cement composition containing coal ash produced by the production method.

Conventionally, as disclosed in the following Patent Document 1 and the like, coal ash generated in a thermal power plant or the like has been used for the production of cementitious compositions.
Japanese Patent Laid-Open No. 7-242457

  However, coal ash generated at thermal power plants and the like is not necessarily suitable for use in the production of cementitious compositions. That is, most of the coal ash generated in thermal power plants and the like contains a relatively large amount of an expansion component such as calcium oxide (CaO), and the cementitious composition mixed with this expands during or after curing. There was a concern of cracking.

  Due to the concerns as described above, in the prior art, most of the coal ash generated at thermal power plants and the like has been discarded as industrial waste except for some high-quality ones. More specifically, in the conventional technology, among coal ash generated at thermal power plants, etc., it is classified into one or two types according to Japanese Industrial Standards standard number: JIS A 6201 (standard name: “fly ash for concrete”). Those specified are used as raw materials for cementitious compositions. However, most of the coal ash generated at thermal power plants and the like is out of the above-mentioned standards and has been discarded as industrial waste. For this reason, from the viewpoint of effective use of resources, it has been desired to effectively use the coal ash that is currently discarded for the production of cementitious compositions.

  Therefore, based on such knowledge, the present invention makes it possible to effectively use coal ash of a quality that cannot be used in the production of cementitious compositions in the prior art, or in the prior art. For producing a coal ash slurry for a cement-based composition capable of making the coal ash further suitable for the production of a cement-based composition, and a cement containing the coal ash produced by the production method An object is to provide a system composition.

  Based on the problems described above, the present inventors have investigated that coal ash that is suitably used for the production of cementitious compositions in the prior art is considered inappropriate in the production of cementitious compositions. We found that the particle size tends to be larger than that of coal ash. In addition, the present inventors have found that the particle size of coal ash can be reduced by charging and stirring the coal ash in a liquid such as water. Furthermore, when the present inventors repeated further examination, it is possible to neutralize expansion components such as calcium oxide (CaO) contained in the coal ash by adding and stirring the coal ash into the liquid. I found it.

  Accordingly, the invention according to claim 1 provided on the basis of such knowledge is a method for producing a coal ash slurry for a cement-based composition comprising a raw material containing coal ash, cement, water and aggregate, and has a passing rate. The raw material is coal ash having a particle size distribution with a 90% particle size larger than 20 μm, and the coal ash is slurried by stirring in liquid until the particle size distribution with a 90% particle size is 20 μm or less. A method for producing a coal ash slurry for a cement-based composition.

  According to such a configuration, coal ash, which has been considered inappropriate for the production of cementitious compositions in the prior art, is produced in the same manner as that used in the production of cementitious compositions in the prior art. The manufacturing method of the coal ash slurry which can be utilized suitably for use can be provided.

  In addition, since the coal ash slurry for cement-based composition produced by the production method of the present invention is a slurry, a cement-based composition in which dry coal ash or coal ash that is simply left after being added is prepared. Compared with the composition, it exhibits significantly higher fluidity. Therefore, if the coal ash slurry produced by the production method of the present invention is used, the cement composition can be used without increasing the amount of chemical admixture (AE agent, water reducing agent, AE water reducing agent, high performance AE water reducing agent). The product can be adjusted to the desired fluidity.

  Here, generally, when the chemical admixture as described above is added as a raw material for the cement-based composition, it increases the manufacturing cost of the cement-based composition, delays the freezing time, decreases workability, decreases strength, etc. There are concerns about the occurrence of various problems as represented. However, as described above, if the coal ash slurry produced by the production method according to the present invention is used as a raw material for the cement-based composition, the amount of chemical admixture added can be suppressed. Therefore, according to the method for producing a cementitious composition of the present invention, the amount of the chemical admixture can be suppressed, and the occurrence of various problems that may occur with the addition of the chemical admixture can be minimized. A fresh coal ash slurry can be provided.

  The invention according to claim 2, which is provided on the basis of the same knowledge, is a method for producing a coal ash slurry for a cement-based composition comprising a raw material containing coal ash, cement, water and aggregate, A coal ash having a particle size distribution with a particle size greater than 10 μm with a 50% rate is used as a raw material, and the coal ash is stirred in a liquid until the particle size distribution with a particle size of 10% or less with a 50% pass rate is obtained. It is the manufacturing method of the coal ash slurry for cement-type compositions characterized by making.

  According to this production method, as with the production method according to the first aspect of the present invention, a higher quality coal ash slurry can be provided when used as a cementitious composition.

  About the manufacturing method of the coal ash slurry for cement-type compositions of the said Claim 1 or Claim 2, these inventors are equipped with the stirring tank and the stirring means rotated inside the said stirring tank. In this experiment, coal ash and liquid were added and stirred, and the stirring conditions were investigated. As a result, the inventors of the present invention have made the coal ash finer and more suitable for cement-based compositions by setting the rotation speed of the stirring means to be higher than the predetermined rotation speed, rather than extending the stirring time of the coal ash. As a result, it was found to be beneficial to achieve the optimum condition.

  Therefore, the invention according to claim 3 provided on the basis of such knowledge is characterized in that, when stirring coal ash, the stirring means rotates relative to the stirring tank at a rotational speed of 1000 revolutions per minute or more. It is a manufacturing method of the coal ash slurry for cement-type compositions of Claim 1.

  According to such a manufacturing method, coal ash containing a large particle size can be smoothly atomized, and an optimum state for a cement-based composition can be obtained.

  The invention according to claim 4, which is provided based on the same knowledge, is a method for producing a coal ash slurry for a cement-based composition comprising a raw material containing coal ash, cement, water, and aggregate, which comprises stirring. The coal ash and liquid as raw materials are agitated by a stirrer equipped with a tank and a stirring means rotating inside the stirring tank, and the stirring means is rotated 1000 minutes per minute with respect to the stirring tank when the coal ash is stirred. It is a manufacturing method of the coal ash slurry for cementitious compositions characterized by carrying out relative rotation at the above number of rotations.

  According to such a method for producing a coal ash slurry for a cement-based composition, coal ash containing particles having a large particle size can be smoothly atomized, and an optimum state for a cement-based composition can be achieved.

  Moreover, the cementitious composition using what made the coal ash for cementitious compositions slurry by the manufacturing method of this invention is compared with what mix | blended the coal ash of the dry state, and the coal ash which just left still after adding water. The fluidity is extremely high. Therefore, when the coal ash slurry produced by the production method of the present invention is adopted in the preparation of the cement-based composition, chemical admixtures such as AE agent, water reducing agent, AE water reducing agent, high performance AE water reducing agent, etc. The cement-based composition can be adjusted to a desired fluidity while suppressing the amount used.

  5. The method for producing a coal ash slurry for a cement-based composition according to claim 3 or claim 4, wherein the stirring tank has a cylindrical shape extending in a predetermined direction, and the stirring means is an extension direction of the stirring tank. It is desirable that a spiral stirring blade is attached to a rotating shaft extending along the axis (Claim 5).

  Moreover, the manufacturing method of the coal ash slurry for cement-type compositions of any one of the said Claims 3-5 throws in coal ash in 30 to 40% of range with respect to the capacity | capacitance of a stirring tank. It is desirable that the liquid is introduced in a range of 30% to 40% with respect to the capacity of the stirring tank (claim 6).

  The method for producing a coal ash slurry for a cement-based composition according to any one of claims 3 to 6, wherein the coal ash and the liquid are in a range of 1: 1 to 0.8: 1.2 by weight ratio. It is desirable to carry out the operation so as to be within (claim 7).

  Here, when the present inventors have repeatedly studied, by introducing air or carbon dioxide into the liquid containing coal ash when stirring the coal ash in the liquid, calcium oxide contained in the coal ash It has been found that expansion components such as (CaO) can be neutralized more rapidly.

  Then, the invention of Claim 8 provided based on this knowledge introduce | transduces air or a carbon dioxide into the liquid containing coal ash during stirring of coal ash. It is a manufacturing method of the coal ash slurry for cement-type compositions of any one of these.

  According to this manufacturing method, what becomes an expansion | swelling component, such as a calcium oxide (CaO), can be rapidly neutralized with a carbon dioxide. Therefore, according to the present invention, the content of what becomes an expansion component is small, and a coal ash slurry having a quality suitable for producing a cementitious composition can be rapidly produced.

  In addition, in the method for producing a coal ash slurry for a cement-based composition of the present invention, when air is introduced or carbon dioxide derived from air is used, carbon dioxide present in the air can be used effectively.

  Here, most of the coal ash generated as a by-product in a thermal power plant or the like contains unburned coal (unburned carbon). When coal ash containing a large amount of unburned carbon is used as a raw material for a cement-based composition together with a chemical admixture such as an AE water reducing agent, the chemical admixture is adsorbed by the unburned carbon, and the amount of chemical admixture is increased accordingly. The amount used will increase. Further, as described above, when the amount of the chemical admixture used is increased, not only the production cost of the cementitious composition increases, but also various factors such as a delay in the freezing time of the cementitious composition, a decrease in workability, and a decrease in strength. There are concerns that this problem will occur. Accordingly, when coal ash is used as a raw material for the cementitious composition, it is desirable to reduce the unburned carbon content as much as possible.

  Therefore, in the invention according to claim 9 provided to solve such a problem, the coal ash is agitated in a liquid in which a surfactant is foamed. It is a manufacturing method of the coal ash slurry for cement-type compositions of any one.

  According to this manufacturing method, the unburned carbon contained in the coal ash can be captured and recovered by the surfactant in the foamed state. Therefore, according to the production method of the present invention, a high-quality coal ash slurry can be provided for use as a cement-based composition having a low content of unburned carbon.

  The invention according to claim 10 comprises a coal ash slurry produced by the method for producing a coal ash slurry for a cement-based composition according to any one of claims 1 to 9, cement, water, and aggregate. It is a cement-type composition which consists of a raw material containing.

  The cementitious composition of the present invention uses, as a raw material, a coal ash slurry that has been slurried by the production methods described in the above claims. Therefore, the cementitious composition of the present invention has high fluidity and excellent workability.

  In addition, since the cementitious composition of the present invention uses the above-described coal ash slurry as a raw material, even if a chemical admixture such as an AE water reducing agent is used, the amount used is minimized. can do. Therefore, according to the present invention, it is possible to provide a cement-based composition which is low in production cost and hardly causes problems such as a delay in freezing time and a decrease in strength which are concerned by using a chemical admixture.

  Here, the above-mentioned cementitious composition can use so-called virgin aggregate collected from a quarry or the like as the aggregate. However, from the viewpoint of effective use of resources, it is desirable to use a so-called recycled aggregate produced by crushing concrete waste generated when a concrete structure such as a building is dismantled.

  On the other hand, silica minerals or the like contained in the aggregate constituting the cement-based composition may cause a so-called alkali aggregate reaction with the alkali component contained in the cement-based composition. Presence / absence of alkali-aggregate reaction and reaction rate are assumed to largely depend on the characteristics and amount of the aggregate constituting the cement-based composition and the chemical admixture added as the raw material of the cement-based composition. . Therefore, in the cementitious composition, in order to suppress the alkali aggregate reaction, it is necessary to sufficiently grasp the characteristics of the aggregate used as a raw material or to suppress the amount of chemical admixture used.

  However, recycled aggregates are produced from concrete waste generated at various sites. Therefore, it is difficult to specify a reactive substance that is included in the recycled aggregate and plays a role in causing the alkali aggregate reaction. Therefore, when using a chemical admixture as a composition of a cement-type composition, it is desirable to suppress the usage-amount of a chemical admixture as much as possible.

  Therefore, the invention according to claim 11 provided on the basis of such knowledge is obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste as a part or all of the aggregate, and / or The cement-based composition according to claim 10, wherein recycled aggregate from which the asphalt component has been peeled is used.

  Since the cementitious composition of the present invention uses a coal ash slurry produced by the production method described in any of the above claims as a raw material, even if a chemical admixture is used, the amount used is small. Very few. Therefore, according to the present invention, it is possible to provide a cement-based composition that hardly causes an alkali aggregate reaction even when recycled aggregate is used as all or part of aggregate.

  ADVANTAGE OF THE INVENTION According to this invention, the coal ash for cementitious compositions which can be made into the state which can be effectively used for the manufacture of cementitious composition of the quality of coal ash which cannot be utilized for manufacture of a cementitious composition. The manufacturing method of a slurry and the cement-type composition containing the coal ash slurry manufactured by the said manufacturing method can be provided.

  Subsequently, a coal ash slurry for a cement-based composition (hereinafter simply referred to as a coal ash slurry) and a method for producing a cement-based composition using the coal ash slurry according to an embodiment of the present invention will be described in order. explain.

(Method for producing coal ash slurry)
Coal ash used as a raw material in this embodiment (hereinafter referred to as raw material coal ash as required) is a large amount of by-products generated from a pulverized coal combustion boiler of a coal-fired power plant, and is a Japanese Industrial Standard. (Standard name: “Fly ash for concrete” • Standard number: JIS A 6201). Moreover, the raw material coal ash contains what has a particle size larger than 20 micrometers. More specifically, the raw material coal ash is a coal ash having a particle size distribution in which the particle size having a passage rate of 90% is larger than 20 μm and the particle size having a passage rate of 50% is larger than 10 μm.

  The cement ash for cement composition (hereinafter, referred to as “coal ash slurry” if necessary) prepared in the present embodiment is a slurry obtained by adding the above-described raw material coal ash into water and stirring it. More specifically, the coal ash slurry prepared by the manufacturing method of the present embodiment is stirred by introducing raw coal ash and water (liquid) into a mixer 1 (stirring device) as shown in FIG. It is adjusted by.

  As shown in FIG. 1, the mixer 1 has a cylindrical stirring tank 10 and is provided with stirring means 11 therein. The stirring tank 10 is arranged horizontally as shown in the figure, and both end portions are sealed.

  Inside the agitation tank 10, an agitation means 11 is disposed. The stirring means 11 has a configuration similar to a so-called screw. That is, the stirring means 11 includes a rotating shaft 12 disposed along the longitudinal direction (axial direction) of the stirring tank 10, spiral stirring blades 13 and 14 attached to the rotating shaft 12, and a blade plate 15. It is composed of The rotating shaft 12 is connected to a motor 16 disposed outside the stirring tank 10.

  When the rotating shaft 12 rotates with the operation of the motor 16, the stirring means 11 rotates the stirring blades 13 and 14 and the blade plate 15 in conjunction therewith. As indicated by arrows in FIG. 1, the stirring blades 13, 14 can generate thrust in the direction toward the center from both longitudinal ends of the stirring tank 10 in the stirring tank 10 as the rotation occurs. It can be configured. In other words, the stirring blade 13 disposed on the left side of the stirring tank 10 in FIG. 1 applies a thrust in the direction from the left side to the center side of the stirring tank 10 in the stirring tank 10 as it rotates. Can be generated. Conversely, the stirring blade 14 disposed on the right side of the stirring tank 10 can generate a thrust in the direction from the right side of the stirring tank 10 toward the center side as it rotates.

  The vane plate 15 is attached to a substantially central portion in the longitudinal direction of the rotary shaft 12. The agitation means 11 can generate a thrust in a direction from the inside of the agitation tank 10 upward as indicated by an arrow in FIG. 1 by rotating the blade 15.

  The stirring tank 10 has openings 20 to 22 at positions on the upper side in the illustrated state. The openings 20 and 21 are respectively located at both ends in the longitudinal direction of the stirring tank 10, and the opening 22 is a position corresponding to the blade plate 15 attached to the rotary shaft 12 at the substantially central portion in the longitudinal direction of the stirring tank 10. Exists.

  In the state shown in FIG. 1, a circulating portion 25 is provided above the stirring tank 10. The circulating portion 25 is provided at a substantially central portion in the longitudinal direction of the stirring tank 10 and communicates with the circulating portion 25 through openings 20 to 22 provided in the stirring tank 10.

  The recirculation part 25 has recirculation flow paths 26 and 27, a constriction flow path 28, and a repulsion part 29. The reflux channels 26 and 27 communicate with the openings 20 and 21 provided in the agitation tank 10, respectively. Further, the constricted flow path 28 communicates with the opening 22 of the stirring tank 10. In addition, the circulation channels 26 and 27 communicate with the constriction channel 28 in the circulation portion 25.

  The repulsion part 29 is provided at a position facing the opening 22 connected to the constriction flow path 28. Therefore, when the agitated substance stirred in the agitation tank 10 flows into the constricted flow path 28 through the opening 22, the agitated substance collides with the repulsion portion 29 and changes the direction of the flow. Flow into.

  The raw material coal ash is introduced into the stirring tank 10 of the mixer 1 having the above-described configuration together with water and stirred. Here, the raw material coal ash is charged in a range of 30% to 40% with respect to the capacity of the stirring tank 10. Water is also added in a range of 30% to 40% with respect to the capacity of the stirring tank 10. Moreover, the raw material coal ash and water thrown into the stirring tank 10 are thrown in the range of 1: 1-0.8: 1.2 by weight ratio (raw material coal ash weight: water weight).

  In the production method of the present embodiment, when the raw material coal ash is agitated by the mixer 1, no other admixture or aggregate constituting the concrete is added or added. That is, in the production method of the present embodiment, only the coal ash and water are kneaded at the stage of slurrying the coal ash, and other raw materials such as admixture are not kneaded together. Moreover, in the manufacturing method of this embodiment, what is generally used as mixing water, such as tap water, groundwater, industrial water, is employ | adopted as water thrown into the mixer 1 with raw material coal ash.

  When the raw material coal ash and water are put into the stirring tank 10 under the conditions as described above, the motor 16 of the mixer 1 is operated, and the rotating shaft 12, the stirring blades 13 and 14 and the blade plate 15 constituting the stirring means 11 are moved. Rotate. At this time, the rotating shaft 12, the stirring blades 13 and 14, and the blade plate 15 rotate at a high speed. The rotational speed of the rotary shaft 12 and the like can be adjusted as appropriate, but it is desirable to rotate at a high speed of 1000 revolutions per minute, desirably 1200 revolutions per minute, and 1400 revolutions per minute. Most desirable. In the present embodiment, the rotary shaft 12 and the like rotate at a high speed of 1400 revolutions per minute or more.

  As described above, when the rotary shaft 12, the stirring blades 13 and 14, and the blade plate 15 begin to rotate at high speed, thrust is generated in the stirring tank 10 in the direction indicated by the arrow in FIG. Water is stirred. More specifically, when the stirring blades 13 and 14 are rotated, thrust is generated in the stirring tank 10 in the direction from both ends in the longitudinal direction (axial direction) of the stirring tank 10 toward the center. Further, when the vane plate 15 rotates, a thrust is generated in the direction shown in FIG. 1 toward the upper side, that is, toward the circulating portion 25 side. The raw material coal ash and water charged into the stirring tank 10 flows from the both ends of the stirring tank 10 toward the center side under the influence of thrust generated by the rotation of the stirring blades 13 and 14 and collides near the center. . In addition, the mixture of raw material coal ash and water collected near the center of the stirring tank 10 is affected by the thrust generated as the blade 15 rotates, and flows upward in the illustrated state. Flows into the constricted flow path 28 of the circulating portion 25 through the opening 22 provided at substantially the center in the longitudinal direction.

  The mixture of raw material coal ash and water that has flowed into the constricted flow path 28 flows further upward (downstream) and collides with the repulsion part 29. The mixture that has collided in the repulsion unit 29 bounces toward the reflux flow paths 26 and 27, and returns to the both ends of the agitation tank 10 through the flow paths 26 and 27 and the openings 20 and 21.

  The raw material coal ash and water charged into the agitation tank 10 flow and circulate in the agitation tank 10 and the circulating portion 25 as described above while the agitation means 11 is operating. Thus, when predetermined time passes after the stirring of the raw material coal ash and water in the mixer 1 is started, a coal ash slurry in which the raw material coal ash is uniformly dispersed in the stirring tank 10 is generated.

  The coal ash slurry obtained by kneading raw material coal ash and water as described above can be used as a raw material for concrete as it is, but it can be left in a mixing stirrer or the like for a period of more than half a day. It is desirable to keep it.

  In the method for producing the coal ash slurry of the present embodiment, the stirring time (stirring setting time T) of the raw material coal ash and water by the mixer 1 is the coal ash dispersed in the water when the raw material coal ash is slurried. The time required to adjust the particle size distribution so that the particle size distribution is 90 μm and the particle size distribution is 90 μm and the particle size distribution is 50 μm and the particle size is 10 μm or less. Set to Further, the required stirring time t can be derived by experiments or the like. When stirring using the above-described mixer 1 as in the present embodiment, the stirring setting time T is adjusted between about 2 to 5 minutes.

  In the manufacturing method of the cementitious composition of this embodiment, it mix | blends by mixing the coal ash slurry manufactured as mentioned above with cement, water, a chemical admixture, and an aggregate in a predetermined ratio. Here, in the method for producing a cement-based composition shown in the present embodiment, not only a so-called virgin aggregate (coarse aggregate, fine aggregate) collected in a quarry or the like is used as an aggregate, As a part or all of the aggregate, a so-called recycled aggregate obtained by processing a lump of concrete waste generated at a building demolition site or the like can be used. Hereinafter, the manufacturing method of the reproduction | regeneration aggregate utilized by this embodiment is demonstrated.

(Recycled aggregate manufacturing method)
Subsequently, a method for producing a recycled aggregate employed in the present embodiment will be described in detail with reference to the drawings. FIG. 2 is a conceptual diagram schematically showing a recycled aggregate manufacturing method employed as a raw material in the concrete manufacturing method of the present embodiment. The recycled aggregate production method shown in FIG. 2 is roughly divided into three flows: a pretreatment flow, a coarse aggregate collection flow, and a fine aggregate collection flow. Each of the pretreatment flow, the coarse aggregate recovery flow, and the fine aggregate recovery flow includes a plurality of steps. Hereinafter, a method for manufacturing a recycled aggregate will be described step by step with reference to the drawings.

  The recycled aggregate manufacturing method implemented in the present embodiment is a concrete scrap lump (hereinafter referred to as a concrete lump B if necessary) generated at a demolition site of a building by an aggregate regeneration plant 50 as shown in FIG. Will be processed). More specifically, when processing the concrete block B at the aggregate regeneration plant 50, first, the concrete block B transported by a truck or the like as the first stage (crushing step) of the pretreatment flow is put into the hopper 51. Is done.

  The concrete block B put into the hopper 51 is transferred by the reciprocating feeder 52 which is reciprocating, and is put into the jaw crusher 53 (crusher). Here, the jaw crusher 53 has a fixed plate 55 and a movable plate 56 that reciprocates in a direction approaching and separating from the fixed plate 55 as the rotating body 57 rotates. Therefore, when the concrete block B is introduced between the fixed plate 55 and the movable plate 56 of the jaw crusher 53, it is crushed and becomes a concrete crushed material V. When the crushing process for crushing the concrete block B is completed, the concrete crushed material V is put into the grinding machine 60, and the manufacturing process shifts to the grinding process.

  In the grinding process, the concrete crushed material V is ground by the grinding machine 60. The grinding machine 60 used here is a rod mill type in which a plurality of rod rods 68 (a grinding treatment member) are arranged in a hollow body 65 (stirring chamber) as shown in FIG. The main body 65 is configured to rotate. The grinding machine 60 has a configuration in which an input port 66 for supplying the crushed concrete V is provided on one end side of a cylindrical main body 65 and a discharge port 67 is provided on the other side.

  The discharge port 67 is provided with a universal adjustment plate 70 that can move so as to change the opening diameter. The discharge port 67 makes it possible to select the diameter of gravel crushed stone to be discharged by adjusting the fixing position of the universal adjustment plate 70. Further, a trommel classifier 72 composed of a wire mesh screen 71 is provided outside the discharge port 67. In this embodiment, the rod rod 68 is used as the grinding treatment member. However, the rod rod 68 may be replaced with a steel ball or the like. You may make it grind between gravel crushed stone parts, without using.

  When the crushed concrete V is put together with water into the charging port 66 of the grinding machine 60 and the main body 65 starts to rotate at a predetermined rotational speed, the grinding of the crushed concrete V is started. In the grinding process, the concrete crushed material V and the rod rod 68 collide with each other in the main body 65 and are pulverized, and the mortar component adhering to the surface of the concrete crushed material V is peeled and polished. When the rotation time of the main body 65 reaches a predetermined time, the rotation of the main body 65 stops, the mixture of the crushed concrete V and the mortar adhering thereto is discharged from the discharge port 67, and the grinding process is completed.

  As shown in FIG. 2, the crushed concrete V discharged from the discharge port 67 of the grinding machine 60 in the grinding process is supplied to the vibrating sieve 58, and the processing process shifts to the separation process. In the separation step, the crushed concrete V has a gravel crushed stone portion having a diameter of 30 mm or more (hereinafter referred to as an oversized crushed stone portion U) and a large-diameter gravel crushed stone portion having a diameter of about 5 mm to 30 mm (hereinafter referred to as the crushed concrete V). , And called a coarse gravel crushed stone portion S) and a gravel portion G having a diameter smaller than 5 mm. That is, the coarse gravel crushed stone portion S is crushed to a size corresponding to the coarse aggregate of the crushed concrete V, and the gravel portion G is crushed to a size corresponding to the fine aggregate. is there. The oversized crushed stone U is the same as or slightly smaller than the concrete crushed material V supplied to the jaw crusher 53, and the concrete crushed material V was discharged without being sufficiently crushed by the grinding machine 60. is there. Therefore, the excess crushed stone U is returned to the inlet 66 of the grinding machine 60 as indicated by an arrow in FIG. 2 and crushed again.

  The coarse gravel crushed stone S includes a coarse aggregate component that can be used as a coarse aggregate as a main component, and includes mortar and impurities that adhere to these surfaces. In addition, the gravel component G is mainly composed of a fine aggregate component that can be used as a fine aggregate, and includes mortar and impurities that adhere to these surfaces. When the separation process in which the crushed concrete V is separated into three types according to the particle size in the vibrating sieve 58 is completed, the processing flow shifts from the pretreatment flow to the fine aggregate recovery flow and the coarse aggregate recovery flow.

  When the processing flow proceeds to the fine aggregate recovery flow, the mixture of the gravel components G (mixed crushed material P) selected by the vibrating sieve 58 in the separation step described above is input to the grinding machine 61 and polished. The grinding machine 61 has the same structure as the grinding machine 60 described above. The mixed crushed material P is ground in the grinding machine 61 to become a regenerated fine aggregate N with a small amount of mortar M attached. In the recycled fine aggregate N taken out from the grinding machine 61, impurities such as mortar M and wood chips separated from the mixed crushed material P are mixed. Therefore, the mixture of recycled fine aggregate N and mortar content M taken out from the grinding machine 61 is put into the spiral classifier 75 and discarded including the recycled fine aggregate N (sand), mortar content M and impurities. Separated into things. Waste such as mortar M is separated from water by the thickener 76 and discarded.

  On the other hand, when the processing flow proceeds to the coarse aggregate recovery flow, as shown in FIG. 2, the coarse gravel crushed stone fraction S selected by the vibrating sieve 58 in the above-described separation step is input to the specific gravity sorting device 80, and the processing step Proceeds to the coarse gravel separation process.

  Here, the coarse gravel crushed stone S is mainly composed of the recycled coarse aggregate R from which the mortar M attached to the surface by crushing and grinding by the grinding machine 60 is removed, and is removed by the vibrating sieve 58. Some fine powdered mortar M, impurities, etc. that could not be filled were mixed. The coarse gravel crushed stone S also contains a coarse aggregate-like mortar M which has been hardened to the same particle size as the recycled coarse aggregate R and could not be crushed by the grinding machine 60. Therefore, the coarse gravel crushed stone portion S is input to the specific gravity sorting device 80 in order to sort these and collect the recycled coarse aggregate R.

  When the coarse gravel crushed stone S is input to the specific gravity sorting device 80, the processing step shifts to the coarse gravel separation step. As shown in FIG. 4, the specific gravity sorting device 80 includes a water tank 81 in which separation water is stored. In the water tank 81, a mesh-like screen plate 83 having a large number of through holes 82 is installed substantially horizontally so as to be immersed in the separation water. The upper part of the screen plate 83 functions as a separation chamber 84 for separating the coarse gravel crushed stone S. The lower part of the screen plate 83 is divided into three sections, and a first tank 86a, a second tank 86b, and a third tank 86c are formed. A lower end portion of each tank is opened, and the heavy aggregate that drops from the through hole 82 of the screen plate 83 can be discharged.

  The first, second, and third tanks 86a, 86b, and 86c are provided with air chambers 87a, 87b, and 87c that open downward. The air chambers 87a, 87b, and 87c are configured such that air can be forcibly introduced from the outside independently, and the air in the air can be sucked and discharged. The specific gravity sorting device 80 is configured to repeat supply and exhaust of air to and from the air chambers 87a, 87b, and 87c at a predetermined cycle. In addition, the air supply / exhaust timing in each of the air chambers 87a, 87b, 87c is gradually shifted from the upstream side (first tank 86a side) to the downstream side (third tank 86c side). Therefore, when the specific gravity sorting device 80 is operated, the water level in the water tank 81 moves up and down with the supply and exhaust of air in the air chambers 87a, 87b, and 87c, and the water for separation in the water tank 81 flows from the upstream side toward the downstream side. Ripples.

  A shooter 91 is provided at the downstream end of the water tank 81, that is, downstream of the third tank 86 c, and an inlet 93 (intake portion) that opens toward the separation chamber 84 is provided at the upper end of the shooter 91. ing. A rotary gate 95 that is rotated by a motor is provided inside the inlet 93. The inlet 93 of the shooter 91 is opened over a predetermined height from the upper surface of the screen plate 83, and the upper end of the opening is at a position lower than the water level for separation in the water tank 81. A cut gate 96 for moving in the vertical direction and adjusting the opening degree of the inlet 93 is disposed at the inlet 93 of the shooter 91.

  Above the entrance 93 of the shooter 91, a take-out portion 97 is provided for discharging the coarse gravel crushed stone S accumulated in the separation chamber 84 and having a light specific gravity accumulated on the upper side. The take-out part 97 and the inlet 93 are partitioned by a partition wall 98 (boundary part). The partition wall 98 is inclined outwardly and downward in order to smoothly and naturally flow the aggregate material having a small specific gravity overflowing from the water tank 81 to the outside of the water tank 81.

  Crude gravel crushed stone S introduced into the water tank 81 rides on the pulsation of separation water generated in the water tank 81 in accordance with the operation of the specific gravity sorting device 80 and floats and settles in the water tank 81 and gradually flows downstream. . The mortar and impurities in the coarse gravel crushed stone S have a greater buoyancy when the water flow is generated than the recycled coarse aggregate R, and the amount of sedimentation when the water flow is stopped is small. Therefore, after the coarse gravel crushed stone S is charged, when the specific gravity sorting device 80 continues to operate, the regenerated coarse aggregate R settles in layers downward based on the difference in the floating force and the amount of sedimentation in the water. The mortar part M hardened in the form of coarse aggregate is accumulated. In addition, light weights such as gravel G and fine mortar M are partly piled upward and the rest drifts upward in the separation water. Actually, the amount of mortar attached to the surface of the recycled coarse aggregate R is not uniform depending on the degree of crushing and grinding in the grinding machine 60. Therefore, also about the layer of the reproduction | regeneration coarse aggregate R, the thing with much adhesion amount of mortar moves upwards, and the thing with little adhesion amount of mortar will lie below.

  Of the coarse gravel crushed stone S accumulated in layers on the downstream side of the water tank 81, the recycled coarse aggregate R having a large specific gravity passes through the cut gate 96 and is forcibly taken into the shooter 91 by the rotary gate 95. The recycled coarse aggregate R taken into the shooter 91 is discharged from the opening 100 below the shooter 91 and collected.

  On the other hand, the layer accumulated on the upper side of the water tank 81 is a mixture of a light specific gravity aggregate with a large amount of adhesion of the mortar component M, a fine mortar component M, and impurities such as wood chips. Since these mixtures are wastes of low utility value, they are discarded after removing moisture in the thickener 76.

  In the recycled coarse aggregate R and recycled fine aggregate N collected as described above, the ratio of the mortar component in the total weight of the recycled coarse aggregate R and recycled fine aggregate N is 20% or less, and the ratio of the asphalt component. Is 5% or less, and is a quality that can be suitably used as a part or the whole of the coarse aggregate charged as a raw material in the method for producing a cementitious composition of the present embodiment.

(Method for producing cement-based composition)
In the concrete production method of the present embodiment, cement mortar or concrete is mixed with the coal ash slurry produced by the above-described method for producing coal ash slurry, cement, water, chemical admixture, and aggregate at a predetermined ratio. Is formulated. As the chemical admixture added here, a desired chemical admixture such as a conventionally known AE agent, water reducing agent, AE water reducing agent and / or high performance AE water reducing agent can be arbitrarily selected and employed. Moreover, although normal Portland cement (JIS R 5210) can be used suitably for the cement added here, it is also possible to use other types of cement, for example, early-strength cement.

  In the present embodiment, so-called recycled aggregate is employed as part or all of the coarse aggregate and the fine aggregate generally used as the aggregate. As the recycled aggregate used here, a crushed product obtained by crushing concrete or asphalt waste material by the above-described production method and grinding the mortar component or asphalt component can be employed. The recycled aggregate used in this embodiment desirably has a water absorption rate of 5% or less.

  The recycled aggregate employed in the method for producing a cementitious composition of the present embodiment desirably has a mortar component ratio of 20% or less in the total weight of the recycled aggregate. Although it is difficult to completely remove mortar at the time of production of recycled aggregate, the mortar content can be peeled off until the residual amount of mortar falls within the range of 3% to 20% of the total weight of the recycled aggregate If it has, it can be used suitably for manufacture of concrete. Moreover, as for the recycled aggregate employ | adopted in this embodiment, it is desirable that the ratio of the asphalt component in the total weight is 5% or less with respect to the total weight of the recycled aggregate. It is difficult to completely remove the asphalt component even when producing recycled aggregate from waste material containing asphalt, but the asphalt component is in the range of 1% to 5% with respect to the total weight of the recycled aggregate. Can be suitably used for the production of a cementitious composition.

When coal ash (coal ash slurry) obtained by slurrying raw material coal ash as described above is added to other raw materials such as aggregates, the fluidity is improved as compared with the case where dry coal ash is added. . Therefore, if a cement-based composition such as concrete is produced by the production method of the present embodiment, the addition amount or addition rate of a chemical admixture represented by a high-performance AE water reducing agent can be minimized. More specifically, according to the method for producing a cementitious composition of the present embodiment, the amount of chemical admixture added can be designed to be ½ or less of the conventional formulation. More specifically, according to the manufacturing method of the present embodiment, for example, the amount of the chemical admixture added can be reduced to a level below 2 kg / m ³ . Further, according to the production method of the present embodiment, for example, the amount of the chemical admixture added can be reduced to about 0.5% or less by weight.

  As described above, according to the method for manufacturing a cement-based composition of the present embodiment, the amount of chemical admixture used can be suppressed to the minimum, so that the manufacturing cost of the cement-based composition can be suppressed to a minimum. . In addition, according to the above-described production method, the freezing time of the cement-based composition assumed to occur with the addition of the chemical admixture, the workability deterioration, the strength reduction accompanying so-called alkali aggregate reaction, etc. The occurrence of defects can be minimized.

  In the manufacturing method of the cementitious composition of this embodiment, the usage-amount of the chemical admixture which causes an alkali aggregate reaction is small. Therefore, according to the method for producing a cementitious composition of the present embodiment, the raw material is an aggregate that is unknown or unstable in content such as silica mineral that causes an alkali aggregate reaction, such as recycled aggregate. It is possible to provide a cementitious composition that hardly causes an alkali aggregate reaction even when used.

  Moreover, if raw material coal ash is stirred in water like the manufacturing method of coal ash slurry mentioned above, most of expansion | swelling components, such as calcium oxide (CaO) contained in raw material coal ash, are neutralized. Can do. Therefore, if the coal ash slurry produced as described above as in the present embodiment is used as a raw material in the production of a cement-based composition, a cement-based composition that is less prone to problems such as expansion cracks even during and after curing. Things can be provided.

  Moreover, the mixed water stirring time of coal ash can be appropriately adjusted in consideration of the fresh properties of the cementitious composition or the physical properties during or after curing. That is, in the concrete production method of the present embodiment, the conditions such as the time for mixing and stirring the raw material coal ash, the input amount of the raw material coal ash and water, and the like are appropriately adjusted while considering the particle size distribution of the raw material coal ash. Thus, the fresh properties of the cementitious composition and the physical properties at the time of curing or after curing (flow value, expansibility of concrete, strength, etc.) can be appropriately adjusted.

  Here, in the said embodiment, the example which made the raw material coal ash mixed and stirred by the mixer 1 into the slurry as a raw material of cementitious composition was illustrated. However, the present invention is not limited to this, and when the raw material coal ash is made into a slurry, or after being made into a coal ash slurry and further processed separately, the raw material of the cementitious composition may be used. Is possible.

  More specifically, most of the coal ash that becomes the raw material coal ash is generated in thermal power plants, etc., but depending on the quality of coal used in thermal power plants, etc., the amount of unburned carbon in the coal ash Is often included. When coal ash containing a large amount of unburned carbon is used as a raw material for concrete, the air entrainment to concrete is hindered, or the hydrogen ion concentration (pH) of concrete due to calcium oxide contained in coal ash May increase and cause problems such as expansion cracks in concrete. Therefore, when there is such a concern, for example, when the raw material coal ash is processed into the coal ash slurry by the above-described manufacturing method, the following stabilization treatment can be performed. Hereinafter, the stabilization process of a coal ash slurry is demonstrated in detail.

(Coal ash slurry stabilization treatment)
The stabilization processing of the coal ash slurry is performed by adding a surfactant and causing foaming when the coal ash slurry is manufactured or after the coal ash slurry is manufactured.

  When the surfactant is added when producing the coal ash slurry, the surfactant is introduced into the stirring tank 10 of the mixer 1 together with the raw coal ash and water in the above-described coal ash slurry production process. Thereafter, when the mixer 1 is operated, the surfactant is foamed in the stirring tank 10, and most of the unburned components contained in the raw coal ash are taken into the foam.

  When a predetermined operation time has elapsed since the mixer 1 started to operate as described above, the mixer 1 is stopped. Here, the operating time (stirring setting time T) of the mixer 1 is the same as the above-described method for producing the coal ash slurry, when the raw material coal ash is slurried, and the passage rate of the coal ash dispersed in the water is determined. The 90% particle size is 20 μm or less, and the passing rate is set to be not less than the time necessary for adjusting the particle size distribution to be 50 μm or less (10 minutes required for stirring). The

  When the set stirring time T has elapsed since the mixer 1 started to operate as described above, the stirring by the mixer 1 is stopped. Then, the foam component which exists in the stirring tank 10 of the mixer 1 is discharged | emitted using the pump etc. which are not shown in figure. Thereby, the coal ash which hardly contains unburned components remains in the stirring tank 10 in a slurry state.

  On the other hand, when the surfactant is added after the coal ash slurry is produced, the raw material coal ash is slurried with the mixer 1 by the method for producing the coal ash slurry described in detail above, and then the mixture is put into the stirring tank 10 of the mixer 1. Surfactant is charged or the coal ash slurry is transferred from the stirring tank 10 to a separately prepared stirring device (not shown), and the surfactant is charged and stirred.

  After the surfactant is put into the coal ash slurry as described above, when the mixer 1 or a separately prepared stirring device is operated, the surfactant is foamed and dispersed in the coal ash slurry. Coal ash, which is an unburned component, is captured. When a predetermined time elapses after the operation of the mixer 1 and the stirring device starts, the mixer 1 and the stirring device are stopped, and the foam component is discharged using a pump or the like. Thereby, the coal ash slurry which hardly contains an unburned component is formed.

Here, when the raw material coal ash is slurried by the method for producing the coal ash slurry shown in the above embodiment, some air is taken into the water with stirring. Therefore, if the coal ash slurry is produced by the production method as described above, the high alkali component contained in the coal ash slurry is caused by carbon dioxide (CO ₂ ) contained in the air taken into the water. Can neutralize to some extent.

  In the method for producing the coal ash slurry shown in the above embodiment, the coal ash slurry can be neutralized to some extent by the air naturally taken in during stirring, but the present invention is not limited to this. More specifically, a gas introducing means for introducing air or carbon dioxide is provided in the stirring tank 10 of the mixer 1, and the air is supplied at an appropriate timing during the stirring of the raw coal ash or after the raw coal ash is slurried. Alternatively, it may be neutralized by blowing or carbon dioxide. With such a configuration, when the raw coal ash or coal ash slurry contains a high alkali component in an amount that cannot be neutralized only by air that is naturally taken in when stirring with the mixer 1 or the like. Even if it exists, these can be neutralized reliably.

Further, with the configuration to be introduced into the stirring tank 10 such as air or carbon dioxide as described above, can also be effectively utilized for carbon dioxide (CO ₂₎ contained in the air, contributing to the so-called CO ₂ measures it can.

  In the said embodiment, although the structure which the stirring means 12 of the mixer 1 rotated at high speed inside the stirring tank 10 was illustrated as one Embodiment of this invention, this invention is not limited to this, The stirring tank 10 It is good also as a structure which the side rotates at high speed with respect to the stirring means 12, or a structure in which both the stirring tank 10 and the stirring means 12 rotate. In other words, the mixer 1 only needs to be such that the stirring means 12 rotates relative to the stirring tank 10.

  In the above embodiment, as an example of the liquid stirred together with the raw coal ash, water or an example in which a surfactant is added to water is exemplified, but the present invention is not limited to this, You may employ | adopt liquids other than these. Moreover, in the said embodiment, although the example which introduce | transduces water and surfactant as what is stirred together with raw material coal ash was illustrated, things other than water and surfactant like a conventionally well-known dispersing agent, for example were used. It is good also as a structure thrown in with raw material coal ash.

  In the above embodiment, an example in which the recycled aggregate is adopted as a part or all of the aggregate is illustrated. However, all of the aggregate may be constituted by so-called virgin aggregate collected from a quarry or the like. . Moreover, the manufacturing method of the reproduction | regeneration aggregate described in the said embodiment is only an example, and the reproduction B material may be manufactured with the other manufacturing method.

  In the method for producing the coal ash slurry shown in the above embodiment, the raw material coal ash is agitated and slurried in the agitation tank 10 of the mixer 1, and the particle size of the coal ash that is dispersed in water is 90% and the particle size is 20 μm. The particle size distribution was adjusted so that the particle size distribution was 50 μm or less and the particle size distribution was 10 μm or less. However, the condition of the particle size distribution of coal ash dispersed in water was only one of them. It may satisfy. That is, the agitation conditions including the agitation setting time T may be set based only on the condition that the particle size when the passing rate of coal ash dispersed in water is 90% is 20 μm or less. Similarly, agitation conditions including the agitation setting time T may be set based only on conditions where the particle size of 50% of coal ash dispersed in water is 50 μm or less.

  In addition, the raw material coal ash used in the method for producing the coal ash slurry shown in the above embodiment has a particle size with a passing rate of 90% larger than 20 μm and a particle size with a passing rate of 50% larger than 10 μm. Although the coal ash has a distribution, the condition of the particle size distribution of the raw material coal ash may satisfy only one of the above conditions. That is, according to the method for producing the coal ash slurry shown in the above embodiment, the coal having a particle size distribution in which the particle size having a passage rate of 90% is larger than 20 μm and the particle size having a passage rate of 50% is smaller than 10 μm. Cement-based composition is also used as ash or coal ash having a particle size distribution with a passing rate of 90% smaller than 20 μm and a passing rate of 50% larger than 10 μm. Thus, a coal ash slurry having suitable properties as a raw material can be provided.

  Next, examples of the present invention will be described. As shown in the above-described embodiment, concrete (cement-based composition hereinafter also referred to as a test sample) prepared using the coal ash slurry prepared by stirring with the mixer 1 and coal ash without being slurried with the mixer 1 A test was conducted to compare the properties of concrete (hereinafter, also referred to as a standard sample) prepared by directly kneading as is.

The test sample and the standard sample were prepared by mixing the raw materials at the mixing ratio shown in Table 1 and rotating the mixer 1 at 1400 revolutions per minute. Specifically, the test sample and the standard sample are prepared by mixing each raw material so that water: cement: coal ash: fine aggregate: coarse aggregate = 178: 270: 178: 576: 977 by weight ratio. It was done. The water cement ratio [W / C] of the test sample and the standard sample was about 65%. The unit coarse aggregate bulk volume of the test sample and the standard sample was 650 [liter / m ³ ], and the actual rate of the coarse aggregate was 59%. In the preparation of the test sample and the standard sample, an amount of AE agent corresponding to 1% by weight with respect to the concrete was blended, and 10% by weight of AE assistant was blended with respect to the concrete.

  For the preparation of the test sample and the standard sample, coal ash specified as two types in Japanese Industrial Standards standard number: JIS A 6201 (standard name: “fly ash for concrete”) was used.

  Test samples and standard samples prepared as described above exhibited properties as shown in Tables 2 to 4. Specifically, as shown in Table 2, the test sample had a slump of 22.5 [cm], which was larger than the standard sample slump (22.0 [cm]). Here, as described above, the water cement ratio and the blending ratio of the AE agent and the AE auxiliary agent are the same between the test sample and the standard sample. Therefore, the test sample was more fluid than the standard sample. In addition, the air amount of the standard sample was 3.4 [%], whereas the air amount of the test sample was 2.4 [%]. Therefore, the compressive strength of the test sample was higher than that of the standard sample (see Tables 3 and 4).

More specifically, the standard samples and the test samples were measured for three strengths of 1, 4 weeks each. As a result, the weekly intensity of the standard sample was in the range of 19.9 [N / mm ² ] to 20.3 [N / mm ² ], whereas the weekly intensity of the test sample was 23.6. [N / mm ² ] to 24.1 [N / mm ² ], and the compressive strength of the test sample was higher by an average value of about 3.7 [N / mm ² ]. The 4-week intensity of the standard sample was in the range of 33.1 [N / mm ² ] to 34.0 [N / mm ² ], whereas the 1-week intensity of the test sample was 23.6 [N / mm ² ]. N / mm ² ] to 24.1 [N / mm ² ], and the compressive strength of the test sample was higher by about 3.5 [N / mm ² ] on average.

  As described above, the test sample using the coal ash slurry prepared in the present example was superior in fluidity and higher in compressive strength than the standard sample in which coal ash was blended as it was. Therefore, it was found that if concrete (cement-based composition) is prepared using a slurry of coal ash, it is possible to provide high-strength concrete with excellent workability.

It is sectional drawing which shows a mixer. It is the conceptual diagram which showed the manufacturing method of the reproduction | regeneration aggregate typically. It is sectional drawing which shows a grinding machine. It is sectional drawing which shows a specific gravity selection apparatus.

Explanation of symbols

1 Mixer (stirring device)
10 Stirrer 11 Stirring means 13, 14 Stirring blade

Claims (11)

A method for producing a coal ash slurry for a cement-based composition comprising a raw material containing coal ash, cement, water and aggregate,
Using coal ash having a particle size distribution with a particle size greater than 20 μm with a passage rate of 90% as a raw material, the coal ash is stirred in the liquid until a particle size distribution with a particle size of 90% and a particle size of 20 μm or less The manufacturing method of the coal ash slurry for cement-type compositions characterized by making into a slurry. A method for producing a coal ash slurry for a cement-based composition comprising a raw material containing coal ash, cement, water and aggregate,
The raw material is coal ash having a particle size distribution with a particle size greater than 10 μm with a 50% passage rate, and the coal ash is stirred in the liquid until the particle size distribution with a particle size of 10 μm or less is 50%. The manufacturing method of the coal ash slurry for cement-type compositions characterized by making into a slurry. The coal ash and liquid as a raw material are stirred by a stirring device equipped with a stirring tank and a stirring means that rotates inside the stirring tank,
The method for producing a coal ash slurry for a cement-based composition according to claim 1 or 2, wherein the agitation means rotates relative to the agitation tank at a rotation speed of 1000 revolutions per minute or more when the coal ash is agitated. . A method for producing a coal ash slurry for a cement-based composition comprising a raw material containing coal ash, cement, water and aggregate,
The coal ash and liquid as a raw material are stirred by a stirring device equipped with a stirring tank and a stirring means that rotates inside the stirring tank,
A method for producing a coal ash slurry for a cement-based composition, characterized in that when stirring coal ash, a stirring means is rotated relative to a stirring tank at a rotational speed of 1000 rpm or more. The stirring tank is a cylindrical one extended in a predetermined direction,
The coal ash slurry for a cement-based composition according to claim 3 or 4, wherein the stirring means has a helical stirring blade attached to a rotating shaft extending along the extending direction of the stirring tank. Manufacturing method. Coal ash is charged in a range of 30% to 40% with respect to the capacity of the stirring tank,
The method for producing a coal ash slurry for a cement-based composition according to any one of claims 3 to 5, wherein the liquid is charged in a range of 30% to 40% with respect to the capacity of the stirring tank. .   The cement according to any one of claims 3 to 6, wherein the coal ash and the liquid are added so that the weight ratio falls within a range of 1: 1 to 0.8: 1.2. Of producing a coal ash slurry for an aqueous composition.   Air or carbon dioxide is introduce | transduced in the liquid containing coal ash during stirring of coal ash, The manufacturing method of the coal ash slurry for cement-type compositions of any one of Claims 1-7 characterized by the above-mentioned. .   Coal ash is stirred in the liquid which made the surfactant foam, The manufacturing method of the coal ash slurry for cement-type compositions of any one of Claims 1-8 characterized by the above-mentioned.   The cement-type composition which consists of a raw material containing the coal ash slurry manufactured with the manufacturing method of the coal ash slurry for cement-type compositions of any one of Claims 1-9, cement, water, and an aggregate.   Recycled aggregate from which mortar component and / or asphalt component has been removed by grinding crushed material obtained by crushing concrete and / or asphalt waste as part or all of aggregate is used. The cement-based composition according to claim 10.

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