JP2020033225A - Manufacturing method of artificial stone material - Google Patents

Abstract

To provide a manufacturing method of an artificial stone material that can inexpensively produce an artificial stone material with high hardness, while retaining the ratio of an artificial stone material crushed powder occupying in a stone raw material.SOLUTION: The present invention relates to a manufacturing method of an artificial stone material that contains as stone raw materials aggregate, a solidification material and water, in which the aggregate contains an artificial stone material crushed powder with an absorption coefficient of 10 mass% or more, and the blending amount of the artificial stone material crushed powder to the stone raw material is 20 mass% or more and 40 mass% or less. The manufacturing method of the artificial stone material includes the steps of: removing blocks with a prescribed grain diameter or more from the artificial stone material crushed powder; smoothing a surface of the removed blocks; mixing the aggregate comprising the blocks after the smoothing step, the solidification material and water; and curing a mixture obtained in the mixing step in a wet state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an artificial stone.

  As one method of effectively using coal ash, steelmaking slag, and the like, there is an artificial stone material in which these materials are solidified using a cementing material such as cement. After the artificial stone itself is used, it becomes waste. However, it is possible to regenerate the artificial stone using the material obtained by crushing the artificial stone to be used as a stone material.

  However, in general, crushed artificial stone powder has a low density and a high water absorption rate, so that its surface is easily dried and hardly wet. For this reason, the artificial stone crushed powder does not sufficiently undergo a hydration reaction with, for example, cement, and the strength of the artificial stone is likely to decrease. Therefore, in the artificial stone material using the artificial stone material crushed powder, the ratio of the artificial stone material crushed powder as the stone material is limited, or the use is not limited to the application in which the strength is not required.

  On the other hand, a method of manufacturing a high-strength artificial stone while using a stone raw material having a high water absorption has also been proposed (for example, see Japanese Patent Application Laid-Open Nos. 9-12349 and 2003-192419). In these conventional methods of manufacturing artificial stone materials, after the stone material having a high water absorption is reduced in particle size, the bulk density of the stone material is improved by granulation treatment or the like, thereby ensuring the strength of the obtained artificial stone material. ing.

  However, such a conventional method of manufacturing artificial stone requires time and effort because it requires a particle size reduction process and a granulation process of the stone material, and requires a respective processing facility, which increases the manufacturing cost. easy.

JP-A-9-12349 JP-A-2003-192419

  The present invention has been made on the basis of the above-described circumstances, and a method of manufacturing an artificial stone material capable of manufacturing a high-strength artificial stone material at low cost while maintaining the proportion of the artificial stone crushed powder in the stone material. The purpose is to provide.

  The present inventors have studied in detail the mechanism by which the strength of the artificial stone material is reduced when the artificial stone material crushed powder having a high water absorption is used. There are many recessed parts, and it is difficult for the consolidated material to adhere to these parts, and fine voids are created at the interface between the artificial stone crushed powder and the consolidated material, so that the strength of the obtained artificial stone decreases. I found it. The present inventors have succeeded in reducing the fine cavities by smoothing the angular and depressed portions of the artificial stone material crushed powder having a relatively large particle size, and can reduce the strength of the obtained artificial stone material. Was reached, and the present invention was completed.

  That is, the present invention made in order to solve the above-mentioned problems includes an aggregate, a consolidated material, and water as stone raw materials, and the aggregate includes artificial stone crushed powder having a water absorption of 10% by mass or more. A method for producing an artificial stone material in which the amount of the artificial stone material crushed powder with respect to the stone material is 20% by mass or more and 40% by mass or less, wherein a step of extracting a lump having a predetermined particle size or more from the artificial stone material crushed powder is taken out. A step of smoothing the surface of the lump, a step of mixing the aggregate containing the lump after the above-mentioned lump, consolidating material and water, and a step of curing the mixture obtained in the mixing step in a wet state And

  In the method for manufacturing an artificial stone material, a lump having a predetermined particle size or more is taken out from the crushed artificial stone powder, and the surface of the lump is smoothed. For this reason, in the mixing step, fine voids are unlikely to be formed at the boundary surface between the crushed artificial stone powder and the consolidated material, and the strength of the obtained artificial stone material can be increased. Further, the above-mentioned smoothing step can be performed by inexpensive means. Therefore, by using the method for manufacturing an artificial stone material, it is possible to manufacture an artificial stone material having high strength at low cost while maintaining the ratio of the crushed artificial stone material as a stone material within the above range.

  The predetermined particle size in the lump removal step is preferably 2 mm or more and 4 mm or less. As described above, by setting the predetermined particle size in the lump removal step to be within the above range, the strength of the obtained artificial stone material can be increased while appropriately controlling the amount of the lump to be smoothed.

  The smoothing step may include a step of attaching a steelmaking slag having a water absorption of less than 5% by mass and a particle size of less than the predetermined particle size to the surface of the lump. In this way, by adhering the steelmaking slag to the surface of the lump in the smoothing step, the surface of the lump is smoothed as artificial stone crushed powder and pseudo-particles of steelmaking slag, and the artificial stone crushed powder and the consolidated material are mixed. The generation of minute cavities at the interface can be suppressed. Further, since the steelmaking slag adheres easily only by being mixed with, for example, crushed artificial stone powder, the cost required for smoothing can be further reduced. Furthermore, since steelmaking slag has a higher basicity and a greater hydraulic effect than fine sand or granulated blast furnace slag, the consolidation strength can be increased during the hydration reaction.

  The above-mentioned smoothing step may include a step of removing the corners of the lump so that the average circularity is 0.76 or more. In this way, the surface of the lump is smoothed, and the interface between the crushed artificial stone material and the compacted material is obtained by performing the corner dropping of the lump so that the average circularity is equal to or more than the lower limit in the smoothing step. The formation of minute cavities can be suppressed. Moreover, since the average circularity of the crushed artificial stone powder can be made to be equal to or more than the above lower limit by, for example, rotating with a rotary drum, a large-scale facility is not required, and the cost required for smoothing can be further reduced.

  Here, the “water absorption rate” is a value calculated by the following procedure. First, several hundred g of a target sample is taken, dried at 105 ° C., and the mass W1 [g] of the sample in a completely dry state is measured. Next, the sample is immersed in water for 24 hours to absorb moisture, and after draining, the water film on the surface is wiped off, and the weight W2 [g] of the sample in the surface dry and saturated state is measured. From these masses, (W2−W1) / W1 × 100 [%] is calculated, and the calculated value is defined as the water absorption.

The “circularity” indicates the degree of circularity, and is represented by 4π × area / (perimeter) ² . The circularity is a numerical value of 0 or more and 1 or less, and when the circularity is 1, it is a perfect circle. Specifically, the average circularity was measured by the following procedure. First, 20 particles are randomly collected from particles placed on a plane, and the perimeter and area are measured from the projected image. Next, the circularity of each particle is calculated from the obtained perimeter and area according to the above formula, and the average value is defined as the average circularity.

  As described above, by using the method for manufacturing an artificial stone of the present invention, an artificial stone having high strength can be manufactured at low cost while maintaining the proportion of the crushed artificial stone in the stone raw material.

It is a flow figure showing the manufacturing method of the artificial stone material concerning one embodiment of the present invention. It is a graph which shows the compressive strength of the artificial stone in the reference example.

[First Embodiment]
Hereinafter, a method for manufacturing an artificial stone material according to an embodiment of the present invention will be described.

  The method for manufacturing an artificial stone shown in FIG. 1 includes an aggregate, a consolidated material, and water as stone raw materials, wherein the aggregate includes an artificial stone crushed powder having a water absorption of 10% by mass or more. Is a method for producing an artificial stone material in which the mixing amount with respect to the above-mentioned stone material material is 20% by mass or more and 40% by mass or less. The method for manufacturing an artificial stone material includes a lump removal step S1, a smoothing step S2, a mixing step S3, and a curing step S4. In addition, the method for manufacturing an artificial stone material includes, as a smoothing step S2, a step of attaching a steelmaking slag having a water absorption of less than 5% by mass and a particle diameter of less than the predetermined particle diameter to the surface of the lump. Prepare.

<Stone materials>
The “stone raw material” as a raw material of the artificial stone refers to all raw materials used in the production of the artificial stone, and includes aggregates including artificial stone crushed powder, consolidated materials, water, additives, and the like. The stone raw material used in the method for producing the artificial stone includes at least an artificial stone crushed powder having a water absorption of 10% by mass or more (hereinafter, also simply referred to as “artificial stone crushed powder”), a consolidated material, and water.

(aggregate)
Aggregate refers to a filler for mixing with a consolidated material to produce an artificial stone such as concrete or mortar.

  As described above, the stone material used in the method for producing artificial stone includes crushed artificial stone as an aggregate. Artificial stone crushed powder is one type of aggregate and is obtained by crushing artificial stone. Artificial stone crushed powder has a relatively high water absorption, usually showing a water absorption of 10% or more.

  The particle size of the crushed artificial stone powder is not particularly limited, but is usually 10 mm or less. The particle size of the artificial stone crushed powder has a relatively wide distribution. For example, in the artificial stone crushed powder crushed so that the maximum particle diameter becomes 10 mm, the artificial stone crushed powder having a particle size of 5 mm or less accounts for 50% by mass or more of the whole. The distribution is such that the artificial stone crushed powder having a particle size of 70% by mass or less and a particle size of 3 mm or less occupies 30% by mass or more and 40% by mass or less of the whole.

  The lower limit of the amount of the artificial crushed stone powder mixed with the stone material is 20% by mass, and more preferably 25% by mass. On the other hand, the upper limit of the amount of the artificial stone material crushed powder is 40% by mass, and more preferably 35% by mass. If the amount of the artificial stone crushed powder is less than the above lower limit, the reuse of the artificial stone becomes insufficient, and the production cost of the obtained artificial stone may increase. Conversely, if the amount of the artificial stone crushed powder exceeds the above upper limit, the strength of the obtained artificial stone may be reduced.

  The above-mentioned stone material may contain other aggregates as the aggregate in addition to the above-mentioned artificial stone crushed powder. Examples of other aggregates include natural aggregates such as sand, gravel and crushed stone, and artificial by-product aggregates such as slag and lime.

  As a minimum of the compounding quantity of the above-mentioned aggregate to the above-mentioned stone material, 60 mass% is preferred and 65 mass% is more preferred. On the other hand, the upper limit of the amount of the aggregate is preferably 80% by mass, and more preferably 75% by mass. If the amount of the aggregate is less than the lower limit, the strength of the obtained artificial stone may be reduced. Conversely, when the amount of the aggregate exceeds the upper limit, the amount of the consolidated material described below is relatively insufficient, so that the production of the artificial stone becomes difficult, and the strength of the obtained artificial stone may be reduced. .

(Consolidation material)
The consolidated material is set and solidified by a hydration reaction, and the aggregate is combined to form an artificial stone material. Various cements can be used as the solidifying material. Cement contains Ca, Si, Al and the like, and oxide ions and Ca ions of these elements existing as monomers come into contact with water to form hydrates such as ettringite, and solidification and solidification progress. As the cement, besides known Portland cement and the like, blast furnace cement containing blast furnace slag containing a large amount of CaO, SiO ₂ , Al ₂ O _3, etc. as a main component and containing about 4% by mass of gypsum can also be used. By using the blast furnace cement in this way, the production cost of artificial stone can be further reduced.

  As a minimum of the compounding quantity of the above-mentioned consolidated material to the above-mentioned stone material, 10 mass% is preferred and 15 mass% is more preferred. On the other hand, the upper limit of the amount of the binder is preferably 30% by mass, more preferably 25% by mass. When the compounding amount of the above-mentioned consolidated material is less than the above lower limit, the aggregate cannot be sufficiently bonded, and the strength of the obtained artificial stone material may be reduced. Conversely, if the amount of the consolidated material exceeds the upper limit, the aggregate is relatively insufficient, and the strength of the obtained artificial stone may be reduced.

(water)
Water is added to cause the hydration reaction of the consolidated material.

  The lower limit of the amount of the water relative to the stone material is preferably 5% by mass, more preferably 7% by mass. On the other hand, the upper limit of the amount of water is preferably 15% by mass, and more preferably 12% by mass. If the amount of the water is less than the lower limit, the fluidity of the stone raw material also deteriorates, so that the hydration reaction does not sufficiently occur, and the strength of the obtained artificial stone may decrease. Conversely, when the amount of the water exceeds the upper limit, unnecessary water remains, so that the strength of the obtained artificial stone may be reduced, and its removal, for example, time may be required for evaporation. There is a possibility that the production efficiency of the product may be reduced and the production cost may be increased.

  The lower limit of the ratio of water to water (cement ratio) is preferably 0.4, more preferably 0.45. On the other hand, the upper limit of the water cement ratio is preferably 0.6 and more preferably 0.55. When the water-cement ratio is less than the lower limit, the hydration reaction does not sufficiently occur, and the strength of the obtained artificial stone material may be reduced. Conversely, when the water-cement ratio exceeds the upper limit, unnecessary water remains, so removal of the water, for example, time is required for evaporation, the production efficiency of artificial stone decreases, and the production cost increases. There is a risk.

(Additive)
The stone raw material may contain various additives. As such an additive, for example, a surfactant that disperses moisture and promotes a hydration reaction can be exemplified. As the surfactant, for example, an AE water reducing agent can be used.

  The amount of the additive (addition amount of each additive when a plurality of types of additives are used) is very small. For example, the amount of the additive to the stone material is less than 1% by mass, preferably 0%. It is less than 0.5% by mass.

  The stone material may be prepared by mixing except for water, or may be separately prepared for each type. In particular, from the viewpoint of the processing efficiency of the lump removal step S1 described below, it is preferable that the artificial stone material crushed powder is separately prepared from the others.

<Lump removal process>
In the lump extracting step S1, lump having a predetermined particle size or more is extracted from the crushed artificial stone powder.

  The method of removing the lump is not particularly limited, but can be performed by, for example, using a sieve having a mesh having the predetermined particle size, sifting the crushed artificial stone powder, and removing the crushed artificial stone powder remaining on the sieve. .

  The lower limit of the predetermined particle size that defines the size of the lump to be taken out is preferably 2 mm, more preferably 2.5 mm. On the other hand, the upper limit of the predetermined particle size is preferably 4 mm, more preferably 3.5 mm. If the predetermined particle size is less than the lower limit, the amount of lumps to be treated in the smoothing step S2 to be described later increases, so that the production efficiency of the artificial stone material may decrease, and the production cost may increase. Conversely, when the predetermined particle size exceeds the upper limit, in the mixing step S3 described later, the proportion of the artificial stone material crushed powder in which fine voids are generated at the interface with the consolidated material increases, so that the obtained artificial stone material The strength may be reduced.

<Smoothing step>
In the smoothing step S2, the surface of the extracted lump is smoothed. Specifically, a steelmaking slag having a water absorption of less than 5% by mass and a particle size of less than the predetermined particle size is attached to the surface of the lump.

  Steelmaking slag is slag generated in a steelmaking process and functions as an aggregate in the production of artificial stone. Examples of such steelmaking slag include converter slag. Steelmaking slag has a relatively low water absorption, usually showing a water absorption of 5% or less.

  As a method for obtaining steelmaking slag having a particle diameter smaller than the predetermined particle diameter, for example, a sieve having a mesh having the predetermined particle diameter can be used as in the lump removing step S1. The steelmaking slag is sieved, and the sieved steelmaking slag may be used.

  Since the steelmaking slag can be attached to the surface of the lump only by mixing the steelmaking slag and the lump, for example, it can be performed without using special equipment such as a granulator. Therefore, equipment costs for manufacturing artificial stone can be reduced. Further, in order to promote the adhesion of the steelmaking slag to the surface of the lump, it is preferable to further add water and mix. The amount of water to be added is preferably 5% by mass or more and 7% by mass or less based on the mass. If the amount of water is less than the lower limit, the effect of promoting the adhesion of the steelmaking slag may be insufficient. Conversely, if the added amount of water exceeds the above upper limit, the effect of washing away the steelmaking slag with water is superior, and the steelmaking slag may not sufficiently adhere to the lump.

  The time for mixing the steelmaking slag and the lump may be a time sufficient for the steelmaking slag to adhere to the lump, and is, for example, 3 minutes or more.

  Since the particle size of the steelmaking slag is smaller than the particle size of the lump, the steelmaking slag mainly adheres to the depressed portion of the lump and forms pseudo particles in which the surface of the lump is smoothed. Therefore, in the mixing step S3, it is possible to suppress the occurrence of fine voids at the interface with the consolidated material.

  In addition, the pseudo particles have a reduced water absorption at a portion where the slag is attached due to the steel slag attached to the surface. Therefore, the surface of the pseudo-particles can be easily maintained in a wet state as compared with a single artificial stone crushed powder. Therefore, the hydration reaction in the mixing step S3 and the curing step S4 can be promoted.

<Mixing process>
In the mixing step S3, the aggregate containing the lumps, the consolidated material, and the water after the smoothing step are mixed.

  Specifically, to the above-mentioned lump after the smoothing step S3, crushed artificial stone particles having a particle diameter smaller than a predetermined particle diameter, which is the remaining part after removing the above-mentioned lump in the lump removing step S1, and steelmaking slag as necessary were added. An aggregate, a consolidated material, water, and a stone raw material to which an additive is added as necessary are mixed with a kneading mixer such as a concrete mixer. In addition, when steelmaking slag is added, the particle size is not particularly limited, and the steelmaking slag may include a steelmaking slag having a predetermined particle size or more used in the smoothing step S2.

  The hydration reaction is started by mixing the stone materials. The mixing time of the stone raw material is not particularly limited as long as the mixing time is such that a hydration reaction occurs, and is, for example, 3 minutes or more.

<Curing process>
In the curing step S4, the mixture obtained in the mixing step S3 is cured in a wet state. This curing step S4 promotes the hydration reaction and improves the strength of the artificial stone obtained.

  The curing step S4 may be performed by immersing the mixture in water, but may be performed under conditions that do not dry the mixture. For example, the mixture may be covered with a wet cloth or the like and cured in the atmosphere. The curing period is appropriately set so that the strength is sufficiently improved, and is, for example, 25 days or more.

<Advantages>
In the method for manufacturing an artificial stone material, a lump having a predetermined particle size or more is taken out from the crushed artificial stone powder, and the surface of the lump is smoothed. For this reason, in the mixing step S3, fine voids are unlikely to be formed at the interface between the crushed artificial stone powder and the consolidated material, and the strength of the obtained artificial stone material can be increased. Further, the smoothing step S2 can be performed by inexpensive means. Therefore, by using the method for manufacturing an artificial stone material, it is possible to manufacture an artificial stone material having high strength at low cost while maintaining the ratio of the crushed artificial stone material as a stone material within the above range.

  In the method of manufacturing an artificial stone material, a step of attaching a steelmaking slag having a water absorption of less than 5% by mass and a particle diameter of less than the predetermined particle diameter to the surface of the lump as the smoothing step S2. Prepare. By adhering the steelmaking slag to the surface of the lump in the smoothing step S2 in this manner, the surface of the lump is smoothed as artificial stone crushed powder and pseudo-particles of the steelmaking slag, and the artificial stone crushed powder and the consolidated material are mixed. The generation of minute cavities at the interface can be suppressed. Further, since the steelmaking slag adheres easily only by being mixed with, for example, crushed artificial stone powder, the cost required for smoothing can be further reduced. Furthermore, since steelmaking slag has a higher basicity and a greater hydraulic effect than fine sand or granulated blast furnace slag, the consolidation strength can be increased during the hydration reaction.

[Second embodiment]
Hereinafter, a method for manufacturing an artificial stone material according to an embodiment of the present invention, which is different from the first embodiment, will be described.

  The method for manufacturing an artificial stone material includes an aggregate, a consolidated material, and water as stone materials, wherein the aggregate includes a crushed artificial stone powder having a water absorption of 10% by mass or more, and This is a method for producing an artificial stone material in which the blending amount with respect to the raw material is 20% by mass or more and 40% by mass or less. The method for manufacturing an artificial stone material includes a lump removing step, a smoothing step, a mixing step, and a curing step. In addition, the method for manufacturing an artificial stone material includes, as a smoothing step, a step of removing a corner of the lump so that the average circularity is equal to or more than a predetermined value.

  The stone raw material is the same as the stone raw material in the first embodiment, and a detailed description thereof will be omitted. In addition, in the method for manufacturing an artificial stone material, the lump removing step, the mixing step, and the curing step are the same as the lump removing step S1, the mixing step S3, and the curing step S4 in the first embodiment, and thus a detailed description thereof will be omitted.

<Smoothing step>
In the smoothing step, the surface of the extracted lump is smoothed. More specifically, the block is cut so that the average circularity of the block becomes a predetermined value or more.

  The predetermined value, which is the target value of the average circularity after the corners are dropped, is preferably 0.76 or more, more preferably 0.8 or more. When the above-mentioned predetermined value is less than the above-mentioned lower limit, the effect of smoothing the above-mentioned lumps becomes insufficient, and fine voids are easily generated at the interface between the crushed artificial stone powder and the consolidated material. For this reason, the strength of the obtained artificial stone material may be insufficient.

  The corners can be cut by, for example, rotating the blocks using a rotating drum. As described above, the predetermined value, which is the target value of the average circularity, can be set relatively low, for example, 0.76, so that highly accurate circularization processing using a granulator or the like can be omitted. For this reason, since special equipment such as a granulator is not required, equipment cost for producing artificial stone can be reduced.

  The number of rotations when the above-mentioned lump is removed using a rotating drum can be, for example, 1000 rotations or more and 2000 rotations or less. If the rotation speed is less than the lower limit, there is a possibility that the angle of the lump is insufficiently reduced. Conversely, if the number of rotations exceeds the upper limit, the time required to cut off the lumps becomes unnecessarily long, so that the production efficiency of the artificial stone material may be reduced and the production cost may be increased.

<Advantages>
In the method of manufacturing an artificial stone material, the surface of the mass is smoothed by dropping the lump so that the average circularity is equal to or more than a predetermined value in the smoothing step, so that the artificial stone material is compacted with the crushed powder. The generation of fine voids at the interface with the material can be suppressed. Moreover, since the average circularity of the crushed artificial stone powder can be made to be equal to or more than the predetermined value by, for example, rotating it with a rotating drum, large-scale equipment is not required, and the cost required for smoothing can be further reduced.

[Other Embodiments]
In addition, the manufacturing method of the artificial stone material of the present invention is not limited to the above embodiment.

  In the first embodiment, a case in which steelmaking slag is adhered to a lump of crushed artificial stone as the smoothing step will be described. In the second embodiment, a case in which the lump is squared off as the smoothing step will be described. Although described, the smoothing step is not limited to these.

  In addition, both the attachment of steelmaking slag and the removal of lumps can be performed. By performing both of the smoothing processes in this manner, both the depressed portion and the angular portion of the crushed artificial stone powder are smoothed, so that the effect of the smoothing can be further improved. In the case where both of the above-described processes are performed as the smoothing process, it is preferable that the steelmaking slag is attached after the corners are cut off. By performing the smoothing treatment in this order, the steelmaking slag can be effectively attached.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[Stone materials]
Aggregate, consolidated material, water, and additives were prepared as stone materials.

(aggregate)
Artificial stone crushed powder and steelmaking slag were prepared as the aggregate. The maximum particle size is 10 mm in each case. Tables 1 and 2 show the specifications and particle size distribution of the artificial stone crushed powder and steelmaking slag. The amount of the above-mentioned aggregate (sum of artificial stone crushed powder and steelmaking slag) with respect to the above-mentioned stone raw material was 70% by mass.

(Consolidation material)
Blast furnace slag was prepared as the consolidated material. The amount of the above-mentioned consolidated material with respect to the above-mentioned stone raw material was set to 20% by mass.

(water)
Water was prepared such that the ratio of water to the above-mentioned consolidated material (water-cement ratio) was about 0.5.

(Additive)
An AE water reducing agent was prepared as the additive, and the amount of the additive relative to the stone material was 0.1% by mass.

<Relationship between amount of artificial stone powder and compressive strength>
First, the relationship between the mixing amount of the artificial stone powder and the compressive strength of the artificial stone produced without performing the smoothing step of the method for producing the artificial stone on the crushed artificial stone powder was examined.

[Reference Example 1]
First, the above-mentioned stone material was kneaded for 3 minutes using a general concrete mixer having a capacity of about 46 L. Thereafter, the obtained mixture was cured for 28 days.

  The mixing amount of the artificial crushed stone powder with respect to the stone raw material was changed from 0% by mass to 60% by mass. The blending amount of the steelmaking slag is changed in accordance with the blending amount of the artificial stone crushed powder, and the blending amount of the aggregate (sum of the artificial stone crushed powder and the steelmaking slag) with respect to the stone material is fixed to 70% by mass. did.

  In addition, curing was performed in two ways, namely, air curing which is kept in the air in a dry state, and underwater curing which is kept in the water (wet state). In this way, an artificial stone material subjected to atmospheric curing and an artificial stone material subjected to underwater curing were obtained.

  According to the above-mentioned procedure, the compressive strength was measured for various artificial stones having different mixing amounts of artificial stone crushed powder and curing conditions. For the compression test, three test samples were manufactured using a container having a diameter of 50 mm and a height of 100 mm, and the compression strength of each test was measured using a commercially available uniaxial compression tester according to JIS-A-1108: 2006. And the average value was calculated. The results are shown in FIG.

  From FIG. 2, it can be seen that when air curing is performed, the compressive strength of artificial stone materials containing more than 10% by mass of the crushed artificial stone powder decreases. In addition, the compressive strength can be improved by performing wet curing, but the compressive strength tends to decrease in artificial stones in which the amount of the artificial stone crushed powder exceeds 20% by mass. It is not sufficiently high in large cases.

<Effect of improving compressive strength>
The effect of improving the compressive strength by performing the smoothing step of the method for producing artificial stone using a stone raw material in which the mixing amount of the artificial stone crushed powder is 40% by mass (the ratio of steelmaking slag is 30% by mass) is examined. Was.

[Example 1]
First, a lump having a particle diameter of 3 mm or more was taken out from the crushed artificial stone powder using a sieve having a mesh of 3 mm. The lump thus taken out was put into a rotating drum, and was turned 1200 times to cut off the corners. At this time, the average circularity of the block was 0.76. As the rotating drum, a cylindrical drum having a diameter of 130 mm and a depth of 200 mm and having two lifters having a height of 20 mm was used at a rotation speed of 30 rpm.

  Using a sieve having a mesh size of 3 mm, a steel slag having a particle size of less than 3 mm (hereinafter, also referred to as “steel slag fine powder”) was taken out. 6% by mass of water is added to the lump of artificial stone crushed powder which has been subjected to the above-mentioned corner-dropping, and this steelmaking slag fine powder is further added and mixed manually for several minutes, and the steelmaking slag fine powder is added to the lump of artificial stone crushed powder. To give pseudo particles.

  Next, the stone material containing pseudo particles obtained by adhering the fine steelmaking slag powder to the crushed artificial stone powder was kneaded for 3 minutes using a general concrete mixer having a capacity of about 46 L. Thereafter, the obtained mixture was subjected to underwater curing for 28 days.

  Thus, the artificial stone material of Example 1 was obtained.

[Example 2]
An artificial stone material of Example 2 was obtained in the same manner as in Example 1 except that the number of rotations of the rotating drum was changed to 600 when the block of the artificial stone material crushed powder was dropped. At this time, the average circularity of the block was 0.74.

[Example 3]
An artificial stone material of Example 3 was obtained in the same manner as in Example 1 except that the lump of the artificial stone material crushed powder was not cut off.

[Example 4, Example 5, Comparative Example 1]
The artificial stone materials of Examples 4, 5, and Comparative Example 1 were respectively made in the same manner as in Examples 1, 2, and 3, except that the fine steelmaking slag powder was not adhered to the mass of the crushed artificial stone materials. I got

[Comparative Example 2 to Comparative Example 7]
The artificial stone materials of Comparative Examples 2 to 7 were obtained in the same manner as in Examples 1 to 5 and Comparative Example 1 except that the curing was air curing.

[Measurement]
The compressive strength of the artificial stone materials of Examples 1 to 5 and Comparative Examples 1 to 7 was measured. Table 3 shows the results. In addition, about the comparative example 1, since the number of samples which can be measured after wet curing was small (N = 1), it was made into the estimated value from the measurement result (N = 3) after air curing. For this reason, in Table 3, () is shown. Specifically, it is known that, when the blending amount of the artificial stone crushed powder is set to 40% by mass and the lump is not attached and the corners are not cut off, the compressive strength is improved by about 6% by humid curing against air curing. Therefore, the value was converted to a value equivalent to wet curing by multiplying by the compressive strength of 1.06 during the atmospheric curing of Comparative Example 1.

  In Table 3, "-" of the number of rotations of the drum means that the corners were not dropped.

  From the results in Table 3, Examples 1 to 3 in which the steelmaking slag fine powder was adhered to the mass of the artificial stone crushed powder and made into pseudo-particles to smooth the depressed portion of the mass and the artificial stone crushed Example 1, Example 4 and Example 5 in which the angular portion of the lump was smoothed by de-squaring the lump of powder were the compressive strengths of Comparative Example 1 or higher in which none of the smoothing processes was performed. It can be understood that it can be done.

  In addition, from the results in Table 3, it can be seen that Examples 1 to 5 in which the wet curing was performed have higher compressive strength than Comparative Examples 2 to 7 in which the air curing was performed.

  From the above results, after removing a lump having a predetermined particle size or more from the artificial stone crushed powder, performing a smoothing process, mixing the stone raw materials, and curing the resulting mixture in a wet state, the artificial strength having a high strength is obtained. It can be said that stone is obtained.

  Furthermore, comparing Example 4 and Example 5 which do not adhere the steelmaking slag fine powder and differ in the number of rotations of the drum, i.e., the circularity after dropping the corner, Example 4 has higher compressive strength. In other words, it can be said that the angle of the block is reduced so that the average circularity is 0.76 or more, so that the strength of the obtained artificial stone can be further increased.

  As described above, by using the method for manufacturing an artificial stone of the present invention, an artificial stone having high strength can be manufactured at low cost while maintaining the proportion of the crushed artificial stone in the stone raw material.

Claims (4)

The aggregate contains aggregates, consolidated materials and water as the stone raw material, wherein the aggregate contains crushed artificial stone powder having a water absorption of 10% by mass or more, and the blending amount of the crushed artificial stone powder with respect to the stone material is 20% by mass A method for producing an artificial stone material that is at least 40 mass% or less,
A step of taking out a lump having a predetermined particle size or more from the crushed artificial stone powder,
A step of smoothing the surface of the mass taken out,
Aggregate containing the lump after the smoothing step, a step of mixing the cement and water,
Curing the mixture obtained in the mixing step in a wet state.   The method for producing an artificial stone material according to claim 1, wherein the predetermined particle size in the lump removing step is 2 mm or more and 4 mm or less. As the smoothing step,
The method for producing an artificial stone material according to claim 1 or 2, further comprising: attaching a steelmaking slag having a water absorption of less than 5% by mass and a particle size of less than the predetermined particle size to the surface of the lump. . As the smoothing step,
The method for producing an artificial stone material according to claim 1 or 2, further comprising a step of cutting off the lump so that the average circularity is 0.76 or more.

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