JP2006306679A - Method for producing cement-based composition, and cement-based composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a cement-based composition where coal ash and reclaimed aggregate can be effectively utilizable as the raw material for a cement-based composition, and to provide concrete. <P>SOLUTION: Coal ash 103 is mixed with water, and the mixture is stirred in a ready-mixed concrete workshop 102 or the like, and is made into slurry. Unburned carbon comprised in coal ash 103 is captured by bubbles generated by the addition of a surfactant, and is recovered. Further, iron comprised in the coal ash 103 is removed from stabilization treated coal ash 104 (coal ash slurry). The coal ash concrete 111 is produced by stirring the coal ash 103 made into the stabilization treated coal ash 104 together with an admixture 107, cement 109 and aggregate 110 by a mixer 108. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a cement-based composition and a cement-based composition formed using the cement-based composition produced by the production method.

  In recent years, the disposal of a tremendous amount of concrete waste generated with the dismantling of concrete structures such as buildings and factories has become a social problem. Concrete waste contains a large amount of aggregate components such as coarse aggregate and fine aggregate. Therefore, from the viewpoint of environmental problems, it is desirable to collect and reuse these aggregate components.

  The above-mentioned concrete waste material is in a state where a mortar component adheres to the surface of the coarse aggregate and fine aggregate contained in the concrete simply by crushing. For this reason, recycled aggregates that are simply crushed concrete waste have high water absorption and are extremely poor in quality for reuse as aggregates. Therefore, the present inventors put the crushed concrete waste into the water in which the water flow is generated in the vertical direction as disclosed in Patent Document 1 below, and the mortar component adheres based on the difference in specific gravity. We have found a way to selectively extract the aggregate components that are not used, and have put them into practical use.

JP 10-25140 A

  Here, conventionally, it has been confirmed that a cement-based composition such as concrete expands due to a so-called alkali aggregate reaction, and cracks and the like may occur. Alkali-aggregate reaction is a phenomenon in which aggregate constituents such as silica minerals and volcanic glass contained in aggregates and alkali components contained in cement cause a long-term chemical reaction. It is considered that the presence or absence and the reaction rate greatly depend on the characteristics of the aggregate.

  In the alkali aggregate reaction, the reaction rate changes when the ratio of the reactive substance exhibiting the reaction is changed. The change in the reaction rate of the alkali-aggregate reaction does not increase with the amount of the reactive substance, but is maximized when the reactive substance is present in a certain proportion (Pecimum phenomenon). The ratio of the reactive substance when the reaction rate of the alkali aggregate reaction is maximized varies depending on the type and composition ratio of the reactive substance contained in the aggregate. For this reason, when using aggregate recovered from waste materials generated at construction sites, such as recycled aggregate, it is difficult to specify the type of reactive substance that plays a role in causing alkali aggregate reaction. It is assumed. Therefore, in order to further promote the use of recycled aggregate, a cement-based composition that can suppress alkali aggregate reaction regardless of the type and composition ratio of the reactive substances contained in the recycled aggregate. There is a need to provide a manufacturing method.

  Therefore, the present invention provides a method for producing a cement-based composition that can suppress alkali-aggregate reaction to a minimum while using recycled aggregate, and a concrete using the cement-based composition produced by the production method. For the purpose of provision.

  Therefore, the invention according to claim 1 provided to solve the above-mentioned problem is a method for producing a cementitious composition prepared by mixing a raw material containing coal ash, cement, water, aggregate and mortar, As a part or all of the aggregate, the recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating the mortar component and / or asphalt component is used. Is a method for producing a cementitious composition, characterized in that

  According to the production method of the present invention, the fluidity of a cementitious composition using a regenerated aggregate can be improved. Therefore, according to the production method of the present invention, the uncured properties (fresh properties) of the cement-based composition such as workability, consistency, plasticity, and finishability of the cement-based composition can be improved. .

  In addition, according to the production method of the present invention, a cement-based composition in which an alkali aggregate reaction is unlikely to occur regardless of the amount or type of the reactive substance that causes the alkali aggregate reaction contained in the recycled aggregate. Can be provided.

  In addition, soluble silica contained in coal ash has a property of densifying the hardened structure of concrete by producing a calcium silicate by reacting with soluble calcium hydroxide generated during the hydration reaction of cement and pozzolanic. Therefore, the cementitious composition of the present invention has an increased long-term strength, improved water tightness, improved resistance to chemicals compared to the case where no coal ash is added, and further reduced the heat of hydration. The properties of the cementitious composition after or after curing can be improved.

  Here, as a result of further studies by the present inventors, it has been found that many of the products obtained as by-products in coal-fired power plants and the like often contain unburned carbon. Unburned carbon has the property of adsorbing chemical admixtures (AE agent, water reducing agent, AE water reducing agent, high performance AE water reducing agent) as a raw material for cementitious compositions. Therefore, when coal ash is added to a part of the raw material during the production of concrete, unburned carbon remaining in the coal ash adsorbs a chemical admixture such as an AE agent. Therefore, when coal ash is added as a part of the raw material, for example, even when blending the same amount of AE agent (air entraining agent) as concrete containing no coal ash, the target air amount of concrete is achieved as desired. It has been found that there is a possibility of problems such as difficulty.

  In addition, when coal ash is mixed as a raw material for the cementitious composition, depending on the type and composition of the coal ash, a large amount of chemical admixture such as a water reducing agent or a high-performance AE water reducing agent may be used to ensure initial fluidity. It has been found that it may be necessary to add. When such a situation occurs, there are concerns that problems such as an increase in the manufacturing cost of the cementitious composition accompanying an increase in the amount of chemical admixture, a delay in setting time, a workability of concrete, and a decrease in strength may occur. The

Further, coal ash contains a relatively large amount of expansion components such as calcium oxide (CaO) and sulfur dioxide (SO ₃ ). Therefore, in concrete mixed with coal ash, there is a concern that partial destruction of the concrete structure due to expansion cracks may occur during or after curing.

  On the other hand, a large amount of coal ash is generated at coal-fired power plants, and most of it is discarded. Therefore, in order to effectively use coal ash as a raw material for cementitious compositions, coal ash can be easily and effectively used as a raw material for cementitious compositions while eliminating the problems associated with the addition of coal ash as described above. There is a need to provide a method for producing such cementitious compositions.

Therefore, the invention according to claim 2 provided based on such knowledge is a method for producing a cementitious composition prepared by preparing a raw material containing coal ash, cement, water and aggregate and mortar,
As a part or all of the aggregate, a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating a mortar component and / or an asphalt component is used. A method for producing a cementitious composition comprising blending with other raw materials in the state of a coal ash slurry that is slurried by mixing with water.

  The cement-based composition prepared by blending the coal ash slurry exhibits remarkably high fluidity as compared with the cement-based composition prepared by blending the dried coal ash or the coal ash that is simply left after addition of water. Therefore, according to the method for producing a cementitious composition of the present invention, the desired flow of concrete can be achieved without increasing the amount of chemical admixture (AE agent, water reducing agent, AE water reducing agent, high performance AE water reducing agent) used. Sex can be achieved. In addition, according to the production method of the present invention, there are problems in the conventional production method in which dry coal ash is mixed with cement, water, and aggregate, that is, the expansibility of the cementitious composition containing coal ash and The problem of strength reduction can be solved.

  Furthermore, according to the method for producing a cement-based composition of the present invention, even if a recycled aggregate contains a substance that causes an alkali-aggregate reaction, the cement-based composition hardly causes an alkali-aggregate reaction. Can provide. Therefore, according to the production method of the present invention, utilization of recycled aggregate and coal ash can be promoted as a raw material for the cementitious composition.

  Invention of Claim 3 is a manufacturing method of the cement-type composition which mix | blended the raw material containing coal ash, cement, water, aggregate, and mortar, Comprising: Concrete and / or as a part or all of the said aggregate Or, use the reclaimed aggregate from which the crushed material obtained by crushing the waste material of asphalt and grinding the mortar component and / or the asphalt component is removed, and the coal ash in the liquid containing the surfactant and foaming the surfactant. A method for producing a cementitious composition comprising blending coal ash that has undergone a step of removing part or all of unburned carbon contained therein and other raw materials.

  According to this production method, unburned components contained in the coal ash can be separated, and the amount of the chemical admixture that can cause an alkali-aggregate reaction can be minimized. Moreover, according to the production method of the present invention, it is possible to provide a cement-based composition that hardly causes an alkali aggregate reaction even if the recycled aggregate contains a substance that can cause an alkali aggregate reaction.

  According to the present invention, the regenerated aggregate can be used as a part or all of the aggregate without any special treatment or test, and the utilization of the regenerated aggregate is promoted to contribute to the effective use of resources. Can do.

  Moreover, according to the manufacturing method of this invention, the desired fluidity | liquidity of concrete can be ensured, suppressing the usage-amount of a chemical admixture. Moreover, according to the manufacturing method which concerns on this invention, the problem of the expansibility of the cementitious composition which mix | blended coal ash and a strength fall can be eliminated.

  Invention of Claim 4 is a manufacturing method of the cementitious composition which mix | blended the raw material containing coal ash, cement, water, and an aggregate and mortar, Comprising: A part or all of the said aggregate is concrete and / or Or, use the reclaimed aggregate from which the crushed material obtained by crushing the asphalt waste material and then removing the mortar component and / or asphalt component was used, and the coal ash was mixed with water for a predetermined time to form a slurry. It is a method for producing a cementitious composition comprising blending with other raw materials in a state of coal ash slurry that has been blown and neutralized to around pH 7.

  In the method for producing a cementitious composition of the present invention, high alkali components contained in coal ash can be neutralized using carbon dioxide in the air by blowing air into the coal ash slurry. Therefore, according to the method for producing a cement-based composition of the present invention, it is possible to provide a cement-based composition in which expansion cracks are unlikely to occur during or after curing of the cement-based composition.

  Moreover, in the manufacturing method of the cementitious composition of this invention, the carbon dioxide contained in the air is used for neutralization of the alkali content contained in coal ash. Therefore, according to the production method of the present invention, the alkali content contained in coal ash can be neutralized easily and inexpensively.

  According to the production method of the present invention, the desired fluidity of concrete can be ensured without increasing the amount of chemical admixture used. Moreover, according to the manufacturing method of this invention, the expansion | swelling of a cement-type composition can be suppressed and the strength reduction accompanying addition of coal ash can be suppressed. Furthermore, according to the manufacturing method of the present invention, waste materials such as coal ash, concrete, and asphalt that have been conventionally treated as industrial waste can be effectively used.

  According to the method for producing a cement-based composition of the present invention, it is possible to provide a cement-based composition that hardly causes an alkali aggregate reaction regardless of which recycled aggregate is used.

  The invention according to claim 5 is a cement-based composition in which coal ash, cement, water, aggregate prepared by mixing coarse aggregate and fine aggregate at a predetermined ratio, and a raw material containing mortar are prepared. A method for producing, using as a part or all of the aggregate, a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating a mortar component and / or an asphalt component, Coal ash is blended by external blending with respect to the unit cement amount, and the fine aggregate is blended by reducing the mass corresponding to the coal ash amount, thereby producing a cementitious composition. Is the method.

  As described above, the target compressive strength and durability after hardening of the cement-based composition can be obtained by manufacturing the cement-based composition by the outer-spread blending of coal ash with cement and water. Can be secured. Moreover, according to the manufacturing method described above, densification of the structure occurs due to the mixing of coal ash, and the strength and durability can be improved from the young age. Furthermore, according to the present invention, it is possible to provide a method for producing a cementitious composition that hardly causes an alkali aggregate reaction regardless of the composition of the recycled aggregate.

  In the method for producing a cementitious composition of the present invention, it is possible to effectively use coal ash, concrete and asphalt waste materials that have been conventionally discarded as industrial waste.

  Invention of Claim 6 is a manufacturing method of the cementitious composition which mix | blended the raw material containing coal ash, cement, water, and an aggregate and mortar, Comprising: As a part or all of the said aggregate, concrete and / or Or use the reclaimed aggregate from which the mortar component and / or the asphalt component is exfoliated by grinding the crushed material obtained by crushing the asphalt waste, and the amount of coal ash and aggregate, as well as the unit cement amount and water cement ratio, By adjusting based on the target strength at the time of curing of the system composition, it is possible to adjust any one or more of the properties, strength and neutralization speed of the cement-based composition when uncured This is a method for producing a cementitious composition.

  According to such a production method, it is possible to provide a cement-based composition capable of arbitrarily adjusting the properties and strength of the cement-based composition when uncured and the neutralization rate.

  In addition, the method for producing a cementitious composition of the present invention uses recycled aggregate made from coal ash, concrete, or asphalt waste, which was often discarded as industrial waste. It can contribute to use.

  In the method for producing a cementitious composition according to any one of claims 1 to 6, the coal ash is preferably mixed and stirred for 24 hours or more.

  In the method for producing a cementitious composition according to any one of claims 1 to 6, it is more desirable that the coal ash is mixed and stirred for 72 hours or more (claim 8).

  The coal ash slurry obtained by mixing and stirring the coal ash for 24 hours or more has a good dispersibility or stability of the slurry, and is a cement-based composition in which dry coal ash or coal ash that is simply left after being added is prepared. Compared with, it shows remarkably high fluidity. In addition, the coal ash slurry obtained by mixing the water for a long time as in the present invention can maintain the fluidity of the cementitious composition at a high level even if the coal ash slurry is allowed to stand after completion of the mixed water stirring. .

  Further, by using a coal ash slurry mixed and stirred for a long time of 24 hours or more as in the present invention, it expands or compresses when the cementitious composition is cured as in the case of using dry coal ash. Can be solved. This is considered to be due to the fact that free lime (CaO) contained in the coal ash is almost completely digested by the mixed water stirring of the coal ash.

  In the method for producing a cementitious composition according to any one of claims 1 to 8, the coal ash is preferably slurried by continuously performing mixed water stirring (claim 9). ).

  According to this structure, a cementitious composition can be manufactured using the coal ash slurry excellent in the dispersibility and stability. Therefore, according to the production method of the present invention, it is possible to provide a cement-based composition that has high fluidity and is less prone to problems such as expansion and decrease in compressive strength during and after curing.

  Further, in the method for producing a cementitious composition according to any one of claims 1 to 9, the coal ash is made into a coal ash slurry by mixing with water and left to stand for more than half a day, and then cement, water and bone. It is desirable to be mixed with a material (claim 10).

  In the manufacturing method of the cementitious composition in any one of Claims 1 thru | or 10, it is also possible to control fresh property by controlling the mixed water stirring time of coal ash (claim 11).

  Here, in this specification, the “fresh property” is represented by workability, consistency, plasticity, finishability, etc., and the physical properties when the cementitious composition is in an uncured state. It points out.

  According to the method for producing a cement-based composition of the present invention, the fresh properties can be controlled by controlling the mixed water stirring time, and the amount of chemical admixture used can be minimized. Therefore, according to the production method of the present invention, it is possible to provide a cement composition with high quality and stability easily and inexpensively.

  Moreover, in the manufacturing method of the cementitious composition in any one of Claims 1 thru | or 11, the physical property of the cementitious composition at the time of hardening or after hardening is controlled by controlling the mixed water stirring time of coal ash. It is also possible (claim 12).

  According to such a production method, a high quality and stable cementitious composition can be provided easily and inexpensively.

  Invention of Claim 13 calculates | requires the mixing | blending from which the fluidity | liquidity of the raw material containing coal ash, cement, water, and mortar becomes the optimal from the gap ratio of a raw material. It is a manufacturing method of the described cementitious composition.

  Here, in this specification, the “gap ratio” is a value obtained by dividing the void amount when the particle group is filled in the container by the total particle group volume, and is an index representing the size of the void amount.

  In the method for producing a cementitious composition of the present invention, the formulation that optimizes the fluidity (flow value, etc.) of the cementitious composition can be theoretically and quantitatively determined based on the theoretically or actually measured gap ratio. it can. Therefore, according to the method for producing a cement-based composition of the present invention, a cement-based composition with stable quality can be provided.

  Moreover, according to the manufacturing method of the cementitious composition of this invention, the coal ash from which a particle size distribution differs can be mix | blended comparatively easily. Therefore, according to the present invention, it is possible to effectively utilize the coarse powder of coal ash that has been considered to be relatively low in the prior art.

  In the invention described in claim 14, the theoretical close-packed gap ratio and the theoretical close-packed composition are obtained from the inherent gap ratio of the raw material to be blended, and the blend with the optimum fluidity is obtained as the theoretical close-packed gap ratio and the theoretical close-packed composition. The method for producing a cementitious composition according to any one of claims 1 to 13, wherein the method is determined based on the formula (1).

  Here, in this specification, the “theoretical close-packed gap ratio” and “theoretical close-packed composition” are theoretically obtained based on the inherent gap ratio of each constituent material of the cementitious composition. In addition, “theoretical close-packed composition” and “theoretical close-packed gap ratio” refer to a composition and a gap ratio that give the minimum value of the theoretical gap ratio in the close-packed packing theory.

  According to the method for producing a cementitious composition of the present invention, the fluidity is excellent and the amount of chemical admixture added can be minimized.

  Invention of Claim 15 is what coal ash contains coarse powder and fine powder finer than coarse powder, and adjusts the mixing ratio of coarse powder and fine powder, coal ash, cement, The method for producing a cementitious composition according to any one of claims 1 to 14, wherein the fluidity of the cementitious composition containing water, aggregate and mortar is adjusted.

  According to such a manufacturing method, it is possible to effectively utilize the coarse powder of coal ash that has been considered to be relatively low in the prior art.

  The method for producing a cementitious composition according to any one of claims 1 to 15, wherein the compressive strength of the concrete is a mortar or a simple cement, and the strength increase value due to coal ash mixing. The strength increase value may be defined as a function of the unit coal ash amount and age (claim 16).

  Moreover, the manufacturing method of the cementitious composition in any one of the said Claims 1 thru | or 16 WHEREIN: The compressive strength of the concrete formed using a cementitious composition makes the void amount of the cement composition after mixing a factor. May be settable (claim 17).

  According to this manufacturing method, the compressive strength of concrete can be accurately grasped, and the mixing ratio of the raw materials of the cement-based composition can be adjusted so as to express the desired compressive strength.

  Here, as a result of intensive studies by the present inventors, the compressive strength of the concrete formed using the cement-based composition produced by the production method described above is highly correlated with the amount of voids having a void diameter of 50 nm or more. Found that there is.

  Accordingly, the invention according to claim 18 provided on the basis of such knowledge is formed using a cementitious composition in accordance with an increase in the void amount, by determining a void amount of 50 nm or more in the void diameter. The method for producing a cement-based composition according to any one of claims 1 to 17, wherein the compressive strength of the cement-based composition can be set.

  According to this manufacturing method, the compressive strength of concrete can be grasped more accurately, and the compressive strength of concrete can be adjusted.

  The method for producing a cementitious composition according to any one of claims 1 to 18, wherein the concrete formed using the cementitious composition is neutralized in accordance with an increase in the amount of unit coal ash. It is also possible to reduce the neutralization rate coefficient to be (claim 19).

  According to this manufacturing method, the speed at which the concrete is neutralized can be accurately grasped, and the raw material for the cement-based composition can be formulated at a blending ratio suitable for suppressing the neutralization of the concrete.

  In the invention according to claim 20, the recycled aggregate is obtained by immersing a polishing mineral obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material in water, and intermittently flowing water from below to above in the water. The method for producing a cementitious composition according to any one of claims 1 to 19, wherein the method is prepared by taking out a gravel / crushed stone layer gathered in a lower layer by being generated.

  A crushed product obtained by crushing concrete and asphalt waste materials has a mortar content and asphalt remaining on the surface, and it is highly possible that the crushed material does not have sufficient quality to be used as an aggregate. Polished minerals obtained by grinding concrete and asphalt crushed material to remove mortar and asphalt contain mixed mortar and asphalt in addition to aggregate components (gravel and crushed stone). Therefore, it is insufficient for use as an aggregate. Therefore, in order to use the recovered material recovered from concrete and asphalt waste as aggregate, it is necessary to remove exfoliation such as mortar and asphalt and impurities contained in concrete waste. . However, it is difficult to separate the aggregate component from the mortar content, the asphalt content, and the like, and in particular, the mortar content is difficult to remove because it looks similar to the aggregate component.

  However, in the present invention, by immersing the abrasive mineral in water in which an intermittent water flow from the bottom to the top is generated, the aggregate component is separated from the mortar and asphalt components using the difference in specific gravity, Gravel and crushed stone layers that are heavier than mortar and asphalt and collect on the lower layer are taken out and used as recycled aggregate. Therefore, the recycled aggregate used in the present invention is a high-quality one that has a small amount of mortar or asphalt attached to the surface and hardly contains impurities.

  Since the recycled aggregate used in the method for producing a cement-based composition of the present invention is high quality as described above, it can be used under the same conditions as so-called virgin aggregate. Therefore, according to the present invention, it is possible to provide a high-quality cementitious composition while using recycled aggregate recovered from concrete or asphalt waste.

  In the method for producing a cementitious composition according to any one of claims 1 to 20, it is desirable to use recycled aggregate having a water absorption of 5% or less (claim 21).

  According to this configuration, the recycled aggregate can be used under the same conditions as the virgin aggregate, which can contribute to the effective use of resources.

  In general, when the water content of the cementitious composition is high, deterioration of strength and neutralization tend to proceed if freeze-thawing is repeated. Since the cement-based composition obtained by the production method of the present invention has a water absorption rate of 5% or less, it is difficult for deterioration and neutralization to occur even if freeze-thawing is repeated.

  The recycled aggregate employed in the method for producing a cementitious composition according to any one of claims 1 to 21 preferably has a mortar component ratio of 20% or less based on the total weight (claim 22). .

  Here, the mortar component generally has a high water absorption rate. For this reason, a cement-based composition using a regenerated aggregate with a large amount of mortar component attached to part or all of the aggregate tends to easily deteriorate in strength or become neutralized by repeated freezing and thawing. The cementitious composition obtained by the production method of the present invention has an aggregate water absorption of 20% or less, so that deterioration and neutralization hardly occur even when freeze-thawing is repeated.

  Similarly, in the recycled aggregate employed in the method for producing a cementitious composition according to any one of claims 1 to 22, the proportion of the asphalt component in the total weight is desirably 5% or less ( Claim 23).

  The invention described in claim 24 is a cement-based composition manufactured by the manufacturing method according to any one of claims 1 to 23.

  Since the cementitious composition of the present invention is prepared by the above-described manufacturing method, it has high strength and is unlikely to suffer from problems such as alkali aggregate reaction and deterioration due to neutralization.

  According to the present invention, a cement-based composition that can effectively use coal ash and recycled aggregate as a raw material for a cement-based composition, and that can solve problems caused by using coal ash as a raw material for the cement-based composition. A production method and concrete using the cementitious composition can be provided.

  Then, the concrete formed by the manufacturing method of the concrete which is a cement-type composition which is one Embodiment of this invention, and the concrete manufactured by the said manufacturing method is demonstrated. In the concrete manufacturing method of the present embodiment, coal ash and recycled aggregate are used as raw materials.

  Coal ash is generated in large quantities as a by-product from pulverized coal combustion boilers of coal-fired power plants. In the concrete production method of the present embodiment, the coal ash is continuously mixed and stirred for 24 hours (1 day) or longer, more preferably 72 hours (3 days) or longer. The coal ash slurry produced by continuous mixed water stirring for 24 hours (one day) or more shows stable slurry properties. In the manufacturing method of the present embodiment, coal ash slurry that has been allowed to stand for half a day or more after stirring is stopped is used for mixing concrete.

  More specifically, the coal ash is charged into a forced kneading pan type mixing stirrer (mixer) together with water. The mixing stirrer is continuously operated for a predetermined time of 24 hours (one day) or more. Thereby, the coal ash thrown into the mixing stirrer is slurried. When the coal ash is slurried, other admixtures and aggregates constituting the concrete are not added or charged into the mixing stirrer. 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, what is generally used as mixing water, such as tap water, ground water, industrial water, is employ | adopted for the kneading | mixing water thrown into a mixing stirrer with coal ash.

  When the coal ash and water are kneaded for 24 hours as described above, a coal ash slurry in which the coal ash is uniformly dispersed in the mixing stirrer is generated. The slurried coal ash can be used as a raw material for concrete as it is, but it is desirable to leave it in a mixing stirrer or the like for a period of more than half a day.

  The coal ash slurry produced in this way is further mixed with cement, water, chemical admixture and aggregate according to a predetermined formulation to prepare cement mortar or concrete. 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. The recycled aggregate used here is obtained by grinding a crushed material obtained by crushing concrete or asphalt waste as in the known art and separating the mortar component and asphalt component. The recycled aggregate used in the present embodiment can be manufactured, for example, by a manufacturing method described later, and the water absorption rate is desirably 5% or less.

  The recycled aggregate employed in the concrete production method 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 is, it can be used suitably for manufacture of concrete suitably. 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. If the asphalt component can be removed, it can be suitably used for the production of concrete.

In the concrete manufacturing method of the present embodiment, the amount or rate of addition of a chemical admixture typified by a high-performance AE water reducing agent can be blended and designed to be ½ or less of the conventional blending. More specifically, according to the manufacturing method of the present embodiment, it is possible to reduce, for example, the amount of chemical admixture added to about 2 kg / m ³ or less. 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.

  Subsequently, a method for producing a recycled aggregate employed in the present embodiment will be described in detail with reference to the drawings. FIG. 1 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 method for producing a recycled aggregate shown in FIG. 1 is roughly divided into three flows: a pretreatment flow, a coarse aggregate recovery flow, and a fine aggregate recovery 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.

  In the method for producing recycled aggregate shown in FIG. 1, a lump of concrete waste material (hereinafter referred to as a concrete lump B if necessary) generated at the site of building demolition in the crushing process, which is the first stage of the pretreatment flow. ) Is transported by a truck or the like and put into the hopper 1.

  The concrete block B put into the hopper 1 is transferred by the reciprocating feeder 2 which is reciprocating and is put into the jaw crusher 3 (crusher). When the concrete block B is thrown in, the jaw crusher 3 has a fixed plate 5 and a movable plate 6 that reciprocates in a direction approaching and separating from the fixed plate 5 as the rotating body 7 rotates. The jaw crusher 3 crushes the concrete block B introduced between the fixed plate 5 and the movable plate 6 to obtain a concrete crushed material V. When the crushing process for crushing the concrete block B is completed, the concrete crushed material V is charged into the grinding machine 10, and the manufacturing process shifts to the grinding process.

  In the grinding process, the concrete crushed material V is ground by the grinding machine 10. The grinding machine 10 used here is a rod mill type in which a plurality of rod bars 18 (a grinding treatment member) are arranged in a hollow body 15 (stirring chamber) as shown in FIG. The main body 15 is configured to rotate. The grinding machine 10 has a configuration in which a loading port 16 for loading the concrete crushed material V is provided on one end side of a cylindrical main body 15 and a discharge port 17 is provided on the other side. The discharge port 17 is provided with a universal adjustment plate 20 that is movable so as to change the opening diameter. The discharge port 17 makes it possible to select the diameter of gravel crushed stone to be discharged by adjusting the fixing position of the universal adjustment plate 20. A trommel classifier 22 made of a wire mesh screen 21 is provided outside the discharge port 17. In this embodiment, the rod rod 18 is used as the grinding member, but this may be replaced with a ball state such as iron, and the rod rod 18 or the grinding member such as the ball state may be used. You may make it grind between gravel crushed stone parts, without using.

  When the concrete crushed material V is thrown into the charging port 16 of the grinding machine 10 together with water and the main body 15 starts rotating at a predetermined rotational speed, the grinding of the concrete crushed material V is started. In the grinding process, the concrete crushed material V and the rod rod 18 collide with each other in the main body 15 and are pulverized, and the mortar component adhering to the surface of the concrete crushed material V is peeled off and polished. When the rotation time of the main body 15 reaches a predetermined time, the rotation of the main body 15 is stopped, and the mixture of the crushed concrete V and the mortar adhering thereto is discharged from the discharge port 17 to complete the grinding process.

  The crushed concrete V discharged from the discharge port 17 of the grinding machine 10 in the grinding process is supplied to the vibrating sieve 8, 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 8 , 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 excessively large crushed stone U is equivalent to or slightly smaller than the concrete crushed material V supplied to the jaw crusher 3, and the concrete crushed material V is discharged without being sufficiently crushed by the grinding machine 10. is there. Therefore, the excess crushed stone U is returned to the inlet 16 of the grinding machine 10 as shown by the arrow in FIG. 1 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 8 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 gravel components G (mixed crushed material P) selected by the vibrating sieve 8 in the above-described separation step is put into the grinding machine 11 and polished. The grinding machine 11 has the same structure as the grinding machine 10 described above. The mixed crushed material P is reclaimed fine aggregate N with a small amount of mortar M attached by being ground in the grinding machine 11. The recycled fine aggregate N taken out from the grinding machine 11 is mixed with impurities such as mortar M and wood chips separated from the crushed material P and atomized. Therefore, the mixture of recycled fine aggregate N and mortar content M taken out from the grinding machine 11 is put into the spiral classifier 25 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 26 and discarded.

  On the other hand, when the processing flow proceeds to the coarse aggregate recovery flow, the coarse gravel crushed stone fraction S selected by the vibrating sieve 8 in the separation step described above is input to the specific gravity sorting device 30 as shown in FIG. Proceed to 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 has been removed by crushing and grinding by the grinding machine 10 and removed by the vibrating sieve 8. Some fine powdered mortar M, impurities, etc. that could not be filled were mixed. The coarse gravel crushed stone portion S also contains a coarse aggregate-like mortar portion M that has been hardened to the same particle size as the recycled coarse aggregate R and could not be crushed by the grinding machine 10. Therefore, the coarse gravel crushed stone portion S is input to the specific gravity sorting device 30 in order to sort these and collect the recycled coarse aggregate R.

  When the coarse gravel crushed stone portion S is input to the specific gravity sorting device 30, the treatment process shifts to the coarse gravel separation process. As shown in FIG. 3, the specific gravity sorting apparatus 30 includes a water tank 31 in which separation water is stored. In the water tank 31, a mesh-like screen plate 33 having a large number of through holes 32 is installed substantially horizontally so as to be immersed in the separation water. The upper part of the screen plate 33 functions as a separation chamber 34 for separating the coarse gravel crushed stone S. The lower part of the screen plate 33 is divided into three sections, and a first tank 36a, a second tank 36b, and a third tank 36c are formed. The lower end portion of each tank is opened, and the heavy aggregate that falls from the through hole 32 of the screen plate 33 can be discharged.

  Air chambers 37a, 37b, and 37c that open downward are provided in the first, second, and third tanks 36a, 36b, and 36c, respectively. Each of the air chambers 37a, 37b, and 37c is configured to be able to forcibly introduce air from the outside independently and to suck and discharge the air inside the air chambers 37a, 37b, and 37c. The specific gravity sorting device 30 is configured such that air supply / exhaust to the air chambers 37a, 37b, and 37c is repeated at a predetermined cycle. In addition, the timing of air supply / exhaust in each air chamber 37a, 37b, 37c is gradually shifted from the upstream side (first tank 36a side) to the downstream side (third tank 36c side). Therefore, when the specific gravity sorter 30 operates, the water level in the water tank 31 moves up and down with the supply and exhaust of air in the air chambers 37a, 37b, and 37c, and the separation water in the water tank 31 flows from the upstream side toward the downstream side. Ripples.

  A shooter 41 is provided at the downstream end of the water tank 31, that is, downstream of the third tank 36 c, and an inlet 43 (intake portion) that opens toward the separation chamber 34 is provided at the upper end of the shooter 41. ing. A rotary gate 45 that is rotated by a motor is provided inside the inlet 43. The inlet 43 of the shooter 41 is opened over a predetermined height from the upper surface of the screen plate 33, and the upper end of the opening is at a position lower than the water level for separation in the water tank 31. A cut gate 46 for moving in the vertical direction and adjusting the opening degree of the inlet 43 is disposed at the inlet 43 of the shooter 41.

  Above the inlet 43 of the shooter 41, a take-out portion 47 is provided for discharging the coarse gravel crushed stone S accumulated in the separation chamber 34 and having a light specific gravity accumulated on the upper side. The take-out portion 47 and the inlet 43 are partitioned by a partition wall 48 (boundary portion). The partition wall 48 is inclined outward and downward in order to smoothly and naturally flow the aggregate material having a small specific gravity overflowing from the water tank 31 to the outside of the water tank 31.

  The coarse gravel crushed stone S introduced into the aquarium 31 rides on the pulsation of separation water generated in the aquarium 31 in accordance with the operation of the specific gravity sorter 30, floats and settles in the aquarium 31, 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, when the specific gravity sorter 30 continues to operate after the coarse gravel crushed stone S is charged, the recycled coarse aggregate R settles in a layered manner 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 10. 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 a layer on the downstream side of the water tank 31, the recycled coarse aggregate R having a large specific gravity passes through the cut gate 46 and is forcibly taken into the shooter 41 by the rotary gate 45. The coarse gravel crushed stone S taken into the shooter 41 is discharged from the opening 50 below the shooter 41 and collected.

  On the other hand, the layer accumulated on the upper side of the water tank 31 is a mixture of light specific gravity aggregate with a large amount of adhesion of the mortar component M, fine mortar component M, and impurities such as wood chips. Since these mixtures are wastes having low utility value, they are discarded after removing moisture in the thickener 26.

  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 mixed as a part or all of the coarse aggregate as a raw material in the concrete manufacturing method of the present embodiment.

  When the coal ash slurried 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, according to the concrete manufacturing method of the present embodiment described above, the addition amount or addition rate of a chemical admixture represented by a high-performance AE water reducing agent can be minimized. In addition, as described above, the cement formed by blending coal ash is unlikely to undergo an alkali aggregate reaction regardless of the type and composition of the recycled aggregate.

  In the concrete manufacturing method of the present embodiment, the mixed water stirring time of coal ash is 24 hours. However, the present invention is not limited to this, and for example, the mixed water stirring may be performed for a longer time. More specifically, for example, the mixed time of coal ash can be arbitrarily set within a range of 24 hours to 72 hours.

  Further, the mixing time of the coal ash mixed water can be appropriately adjusted in consideration of the fresh properties of the concrete or the properties at the time of curing or after curing. That is, in the concrete manufacturing method of the present embodiment, the fresh properties of concrete and the physical properties during or after curing can be controlled based on the mixed water stirring time of coal ash. More specifically, for example, by appropriately setting the mixing time of coal ash within a range of 24 hours to 72 hours, the flow value of cement mortar and concrete mixed with coal ash slurry, the expansibility of concrete, and The strength and the like can be adjusted.

  Here, in the said embodiment, the example which throws coal ash and water into a mixing stirrer as it is and stirs was illustrated. If concrete is manufactured with the manufacturing method of the said embodiment, fluidity | liquidity can be improved and the usage-amount of a chemical admixture can be suppressed. However, depending on the quality of coal used in thermal power plants and the like, a large amount of unburned carbon may be contained in the coal ash. 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 such a situation is a concern, the above-described coal ash slurry is desirably subjected to a stabilization treatment described later before being mixed with cement or the like. Hereinafter, the adjustment method of a coal ash slurry is demonstrated in detail, referring drawings.

The method for adjusting the coal ash slurry roughly includes the steps shown in the following (1) and (2). In the present embodiment, the iron content is further removed in the step (3).
(1) Separating coal ash having a low unburned carbon content from coal ash containing a large amount of unburned carbon by adding a surfactant to the slurryed coal ash to cause foaming.
(2) A highly alkaline coal ash having a pH of 11 to 12 is slurried and blown with air, and neutralized to around pH 7.
(3) Separating iron as iron oxide from slurry-like coal ash using a magnet.

  More specifically, as shown in FIG. 4, the coal ash 103 is transported in powder form from a coal-fired power plant 101 or the like to a ready-mix factory 102 or the like. The coal ash 103 is slurried at the ready-mix factory 102 as shown in step S1 of FIG. Slurry of the coal ash 103 in step S1 is performed similarly to the said embodiment.

  In step S2, concentration of unburned carbon, neutralization of the slurry that has become high pH due to concentration, and recovery of iron (magnetite) are performed. The slurry-like stabilized coal ash 104 produced in the process of step S2 is transported to the mixer 108 with water 106 and admixture 107 added to the existing equipment 105 existing in a general ready-mix factory 102, where cement is added. 109 and aggregate 110 are kneaded and shipped as coal ash concrete 111.

  Next, an example of a coal ash slurry adjustment facility and a method for producing a coal ash slurry using the coal ash slurry adjustment facility will be described in detail with reference to the drawings. FIG. 5 is a schematic diagram of the adjustment facility of the present embodiment, and FIG. 6 is a schematic configuration diagram of a cylindrical slurry mixer employed in the adjustment facility shown in FIG.

  The coal ash 103 discharged from the coal-fired power plant is transported to the factory 102 by a powder transport vehicle 112 or the like and loaded on the stock yard 113. The coal ash 103 loaded in the stock yard 113 is put into the powder container 115 by the belt conveyor 114. The coal ash 103 in the powder container 115 is discharged to a cylindrical slurry mixer 108 installed therebelow.

  As shown in FIG. 6, the mixer 108 includes a supply pipe 116 that supplies coal ash from the powder container 115 into the mixer 108, a water injection pipe 117 that pours water into the mixer 108, and a foam-like discharged ash content into the concrete mixer. A bubble discharge pipe 118 for discharging air, a pneumatic feed pipe 119 for pumping air into the mixer 108, an ash discharge pipe 120 for discharging residual ash, an iron discharge pipe 121 for discharging iron, and a hole having a built-in electromagnet A stirring plate 123 made of a rotating plate is provided. Each pipe is provided with control valves 122A to 122F, respectively.

5 and 6, the coal ash slurry is adjusted through the following steps (1) to (4).
(1) Only the control valves 122A and 122C are opened, and coal ash and water (including a surfactant) are injected into the mixer 8.
(2) Only the control valve 122D is opened, and the stirring plate 123 is rotated while the electromagnet is on while pumping air. After confirming the neutralization, the control valve 122B is opened to discharge the foamy ash.
(3) After closing the control valves 122B and 122D, the control valve 122E is opened while the electromagnet is on, and the coal ash slurry is discharged.
(4) After closing the control valve 122E, the electromagnet is turned off, the control valve 122F is opened, and iron is discharged.

When the coal ash slurry is adjusted as described above, the surfactant added together with water to the coal ash is foamed with the rotation of the stirring plate 23. Most of the unburned carbon contained in the coal ash is recovered by the foamed surfactant. Therefore, when the electromagnetic valve 122B is opened and the surfactant is discharged in the step (2) described above, unburned carbon is discharged to the outside of the mixer 108 together with the coal ash 103 containing almost no unburned carbon. As shown in the above-described embodiment, the coal ash 103 is mixed and stirred for a long period of time, for example, for 24 hours or longer. The slurryed coal ash is neutralized to about pH 7 by CO _{2 in the} air blown in the middle of the mixed water stirring. When it is confirmed that the coal ash slurry has been neutralized to around pH 7, the control valve 122E is opened while the electromagnet is turned on, and the coal ash slurry is discharged. Thereby, the iron content contained in the coal ash slurry is recovered by the electromagnet. When the discharge of the coal ash slurry is completed, the electromagnet is turned off and the control valve 122F is opened. As a result, the iron collected by the electromagnet is discharged from the iron discharge pipe 121.

  By removing unburned carbon from the coal ash slurry as described above, low quality coal ash containing a large amount of unburned carbon can also be sufficiently used as a raw material for concrete. That is, according to the adjustment method described above, regardless of the quality of the coal ash, air entrainment to the concrete is good, the coal ash slurry in a neutral state or a state close to this can be adjusted, and problems such as expansion cracks We can provide the hard-to-occur concrete.

Moreover, if the coal ash slurry is adjusted by the adjustment method described above, resources such as unburned carbon and iron contained in the coal ash can be recovered and reused as raw materials for the ceramic industry, the steel industry, etc. it can. Furthermore, in the adjustment method described above, air or blown air can be used to neutralize water or slurry containing coal ash with carbon dioxide (CO ₂ ) contained therein. Therefore, according to the adjustment method described above, carbon dioxide (CO ₂ ) contained in the air can be effectively used, which can contribute to so-called CO ₂ countermeasures.

  Here, the amount of coal ash to be blended as a concrete raw material in the above-described embodiment can be blended by so-called internal split blending as in the prior art. That is, it is possible to adjust the blending amount of coal ash based on the replacement rate of cement with coal ash. In other words, as shown in Table 1, it is possible to adjust the mixing ratio of coal ash and cement so that the sum of the amount of coal ash and the amount of cement is constant. According to this blending method, not only the amount of expensive cement used can be relatively reduced, but also the use of good quality coal ash has the advantage that the fluidity of the concrete can be improved. Furthermore, when the above-mentioned so-called internal blending is carried out, there is an advantage that the hydration heat generation can be reduced in the high powder concrete.

  On the other hand, when the blending amount of coal ash is adjusted by the above-described internal blending, problems such as a decrease in strength and a decrease in durability tend to occur with an increase in the replacement rate of cement with coal ash. Moreover, when the substitution rate of cement with coal ash is increased, there is a concern that durability may be lowered due to neutralization. For this reason, when adjusting the blending amount of coal ash by the internal split blending, the upper limit value of the unit coal ash amount tends to be regulated by the concrete strength and durability. Therefore, if the internal split blending is adopted, the amount of chemical admixture increases because the amount of coal ash blended is suppressed, and the consumption of coal ash cannot be increased. Etc. may occur and the reaction rate may increase.

  Then, based on this knowledge, the above-mentioned concrete manufacturing method may adjust the blending amount of coal ash by so-called outer split blending. That is, the concrete manufacturing method of the above embodiment is configured such that the blending amount of coal ash with respect to the unit cement amount is set by the outer split blending method, and an amount of coal ash slurry corresponding to this is blended and added to cement or the like. Also good.

  More specifically, when determining the blending ratio of cement, water, aggregate, and coal ash as described above, the unit cement amount is first determined, and the coal ash blending amount is based on this unit cement amount. Is determined by the outer split formulation. Then, the fine aggregate preparation amount is reduced by an amount corresponding to the mass corresponding to the coal ash preparation amount determined here.

  When the outer split blending is performed as described above, the proportion of the coal ash amount in the concrete constituent material becomes larger than that in the case of performing the blending design by the inner split blending. Therefore, when the blending amount of coal ash is adjusted by external blending, the fineness of the constituent materials, the difference in the type of coal ash, and the like have a relatively large influence on the fluidity of the concrete. If the blending amount of coal ash is adjusted by outer split blending, the theoretically derived gap ratio, the gap ratio obtained by actual measurement, or the theoretical closest gap ratio theoretically obtained from the gap ratio inherent to each constituent material Based on the theoretical close-packed composition, it is possible to theoretically and quantitatively determine a formulation that optimizes the fluidity (flow value, etc.) of the concrete and a formulation that can minimize the amount of chemical admixture added.

  Moreover, as above-mentioned, if the compounding quantity of coal ash is adjusted with external preparation, the coal ash from which a particle size distribution differs can be mixed comparatively easily. Therefore, it is possible to effectively utilize coal ash coarse powder that has been conventionally recognized as being relatively low in availability.

  Here, there is a composition in which the flow value becomes maximum when the mixing ratio of fine powder and coarse powder of coal ash is changed in concrete. That is, in the production of concrete, the fluidity of concrete can be optimized by adjusting the mixing ratio of fine powder and coarse powder of coal ash. More specifically, the excess water amount corresponding to the unit water amount is predicted from the relationship between the gap ratio corresponding to the unit water amount in each preparation (maximum gap ratio that can be filled with water) and the gap ratio of the mixed powder. The fluidity of concrete can be adjusted. Therefore, the fluidity of the concrete can be adjusted by adjusting the mixing ratio between the fine powder of coal ash and the coarse powder when carrying out the outer preparation. It is also possible to set the limit at which the addition of a high performance AE water reducing agent or the like becomes indispensable from the gap ratio and the unit water amount.

  Moreover, the compressive strength of the concrete comprised using the concrete manufactured by the manufacturing method of this embodiment adds the strength increase value by coal ash mixing with respect to the compressive strength obtained in the case of a cement plain. Is required. Here, the strength increase value is defined as a function of the unit coal ash amount and the concrete age. That is, the compressive strength of the concrete made using the concrete can be set based on the void amount of the concrete obtained by the manufacturing method of the present embodiment. That is, according to the concrete manufacturing method of the present embodiment, the compressive strength of concrete can be set using the void amount of concrete as a factor. Moreover, the level of compressive strength of concrete is greatly influenced by the amount of voids having a void diameter of 50 nm or more among voids contained in the concrete. Therefore, the compressive strength of concrete can be set with the amount of voids having a void diameter of 50 nm or more as a factor.

  When using coal ash as a raw material as in the concrete of the present embodiment, the neutralization rate coefficient is reduced in accordance with the increase in the amount of unit coal ash. When adjusting the blending amount of coal ash by external blending as in this embodiment, the neutralization rate coefficient can be shown as a function of the unit coal ash amount. When the blending ratio is adjusted by external blending, the neutralization rate coefficient always decreases as the amount of coal ash used increases. Therefore, if coal ash is used in large quantities, neutralization of concrete can be suppressed regardless of the water-cement ratio.

  When the alkali silica reactivity test is performed on concrete made using coal ash as part of the raw material and concrete made without using coal ash by the above-mentioned concrete manufacturing method, coal ash is mixed. The finished concrete tends to exhibit a higher kinematic modulus than concrete without coal ash. In addition, concrete with coal ash mixed has a kinematic coefficient of elasticity that gradually increases with age, whereas concrete without coal ash has a kinematic coefficient of elasticity that increases to a certain age, and then the age of the concrete increases. It tends to decrease as it grows. Therefore, by mixing coal ash into the concrete, a certain effect can be obtained in suppressing the alkali aggregate reaction.

Further, the compressive strength of concrete tends to increase as the water absorption rate of recycled aggregate used as a concrete raw material increases. Further, the compressive strength of concrete tends to increase as the unit coal ash amount (Kg / m ³ ) increases, regardless of the water absorption rate of the recycled aggregate. Therefore, high-strength concrete can be provided by slurrying coal ash as described above, or by blending by external blending.

  In addition, when concrete is produced with the concrete water / cement ratio by the method shown in the above embodiment, the amount of unit coal ash is increased regardless of the water absorption rate of recycled aggregate used as a raw material. The neutral acceleration coefficient tends to decrease.

When concrete freeze-thaw tests were performed on concrete made using coal ash as part of the raw material and concrete made without using coal ash by the above-described concrete production method, Concrete having a relatively high silica content (SiO ₂ ) content tends to have a significant decrease in relative dynamic elastic modulus each time the number of cycles is repeated, compared with concrete having a low silica content. In addition, the concrete with a small amount of coal ash tends to have a lower relative dynamic elastic modulus every time the number of cycles is repeated than the sample concrete with a large amount of coal ash under the same silica content. .

It is the conceptual diagram which showed typically the manufacturing method of the reproduction | regeneration aggregate used in one Embodiment of this invention. It is sectional drawing which shows the grinding machine used in the manufacturing method of the reproduction | regeneration aggregate shown in FIG. It is sectional drawing which shows the specific gravity sorting apparatus used in the manufacturing method of the reproduction | regeneration aggregate shown in FIG. It is a flowchart which shows the flow of the stabilization process of the coal ash implemented in the manufacturing method of the concrete which is one Embodiment of this invention. It is the schematic which shows an example of the adjustment equipment of the coal ash slurry used in the stabilization process of the coal ash shown in FIG. It is a schematic block diagram of the slurry mixer employ | adopted in the adjustment equipment of the coal ash slurry shown in FIG.

Explanation of symbols

103 Coal ash 104 Stabilized coal ash 106 Water 110 Aggregate 111 Coal ash concrete R Recycled coarse aggregate N Regenerated fine aggregate

Claims (24)

A method for producing a cementitious composition in which raw materials including coal ash, cement, water and aggregate and mortar are prepared,
As a part or all of the aggregate, a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating the mortar component and / or asphalt component,
A method for producing a cementitious composition comprising mixing the recycled aggregate and other raw materials. A method for producing a cementitious composition in which raw materials including coal ash, cement, water and aggregate and mortar are prepared,
As a part or all of the aggregate, a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating the mortar component and / or asphalt component,
A method for producing a cementitious composition comprising blending the coal ash with other raw materials in a state of a coal ash slurry obtained by mixing water for a predetermined time to form a slurry. A method for producing a cementitious composition in which raw materials including coal ash, cement, water and aggregate and mortar are prepared,
As a part or all of the aggregate, a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating the mortar component and / or asphalt component,
Coal ash and other raw materials prepared by removing a part or all of unburned carbon contained in coal ash in a liquid containing a surfactant and foamed with the surfactant A method for producing a cementitious composition. A method for producing a cementitious composition in which raw materials including coal ash, cement, water and aggregate and mortar are prepared,
A part or all of the aggregate is a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and peeling off the mortar component and / or asphalt component,
Cement characterized in that the coal ash is blended with other raw materials in a state of coal ash slurry neutralized to about pH 7 by blowing air into a slurry obtained by stirring with mixed water for a predetermined time. Method for producing a system composition. Coal ash, cement, water, an aggregate prepared by mixing coarse aggregate and fine aggregate at a predetermined ratio, and a method for producing a cement-based composition prepared from a raw material containing mortar,
As a part or all of the aggregate, a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating the mortar component and / or asphalt component,
The coal ash is blended by external blending with respect to the unit cement amount,
A method for producing a cementitious composition, wherein the fine aggregate is prepared by reducing the mass corresponding to the amount of coal ash. A method for producing a cementitious composition in which raw materials including coal ash, cement, water and aggregate and mortar are prepared,
As a part or all of the aggregate, a recycled aggregate obtained by grinding a crushed material obtained by crushing concrete and / or asphalt waste material and exfoliating the mortar component and / or asphalt component,
By adjusting the amount of coal ash and aggregate, and the unit cement amount and water cement ratio based on the target strength at the time of hardening of the cement-based composition, the properties, strength and A method for producing a cementitious composition, wherein any one or more of the neutralization rates can be adjusted.   The method for producing a cementitious composition according to any one of claims 1 to 6, wherein the coal ash is slurried by stirring with mixed water for 24 hours or more.   The method for producing a cementitious composition according to any one of claims 1 to 6, wherein the coal ash is slurried by mixing with water for 72 hours or more.   The method for producing a cementitious composition according to any one of claims 1 to 8, wherein the coal ash is slurried by continuously performing mixed water stirring.   The cement ash according to any one of claims 1 to 9, wherein the coal ash is made into a coal ash slurry by stirring with mixed water, and the coal ash slurry is allowed to stand for half a day or more and then mixed with cement, water, and aggregate. A method for producing a system composition.   The method for producing a cementitious composition according to any one of claims 1 to 10, wherein the fresh property is controlled by controlling the mixing time of coal ash mixed water.   The production of a cementitious composition according to any one of claims 1 to 11, wherein the physical properties of the cementitious composition at the time of curing or after curing are controlled by controlling the mixing time of coal ash mixed water. Method.   The cement according to any one of claims 1 to 12, characterized in that a blend that optimizes the fluidity of a raw material including coal ash, cement, water, aggregate, cement mortar, or concrete is obtained from a gap ratio of the raw material. A method for producing a system composition.   Characteristically, the theoretical close-packed gap ratio and the theoretical close-packed composition are obtained from the inherent gap ratio of the raw material to be blended, and the formulation with the optimum fluidity is determined based on the theoretical close-packed gap ratio and the theoretical close-packed composition. A method for producing a cementitious composition according to any one of claims 1 to 13. Coal ash contains coarse powder and fine powder finer than coarse powder,
15. The fluidity of a cementitious composition containing coal ash, cement, water and aggregate and cement mortar or concrete is adjusted by adjusting the mixing ratio of coarse powder and fine powder. The manufacturing method of the cementitious composition in any one of.   Based on the compressive strength of the cementitious composition derived by adding the strength increase value defined as a function of unit coal ash amount and age to the compressive strength obtained in the case of mortar or cement alone The method for producing a cementitious composition according to any one of claims 1 to 15, wherein the blending amount of coal ash is adjusted.   The compressive strength of the cementitious composition formed using the cementitious composition can be set by using the void amount of the cementitious composition after blending as a factor. The manufacturing method of the cementitious composition of this.   A void amount having a void diameter of 50 nm or more is obtained, and the compressive strength of the cement-based composition formed using the cement-based composition can be set in accordance with the increase in the void amount. The manufacturing method of the cementitious composition in any one of 1 thru | or 17.   The method for producing a cementitious composition according to any one of claims 1 to 18, wherein the neutralization rate coefficient of the cementitious composition is reduced in accordance with an increase in the amount of unit coal ash.   Gravel that collects in the lower layer by reclaiming aggregate by immersing abrasive minerals obtained by grinding crushed concrete and / or asphalt waste into ground water and generating intermittent water flow from the bottom to the top of the water. The method for producing a cementitious composition according to any one of claims 1 to 19, wherein the cement-based composition is prepared by removing a crushed stone layer.   The method for producing a cementitious composition according to any one of claims 1 to 20, wherein a recycled aggregate having a water absorption rate of 5% or less is used.   The method for producing a cementitious composition according to any one of claims 1 to 21, wherein a recycled aggregate having a mortar component ratio of 20% or less in the total weight is used.   The method for producing a cementitious composition according to any one of claims 1 to 22, wherein a recycled aggregate having an asphalt component ratio of 5% or less in the total weight is used.   A cementitious composition produced by the production method according to any one of claims 1 to 23.

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