JP2017154950A - Method for producing artificial stone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing artificial stone suppressing the variation of the strength development of artificial stone using mud as raw material and capable of securely expressing desired initial strength in a short time.SOLUTION: Provided is a method for producing artificial stone where mud and an alkali feed material are mixed to obtain a preliminary mixture to breakthrough the alkali adsorptivity of soil grains, then, the preliminary mixture and a binder to cause hydration reaction are mixed to obtain a mixture, and, the mixture is cured by hydration reaction to securely obtain desired initial strength in a short time. The alkali feed material is preferably steel slag, and the binder is preferably blast furnace slag.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing artificial stone manufactured using mud and slag. In particular, the present invention relates to a method for producing an artificial stone with a short curing period until reaching a desired strength.

  Mud soil contains soil particles and water, and has a high water content ratio. For example, dredged soil caused by dredging, such as navigation routes, anchorages, rivers, or construction soil discharged by construction work such as excavation. Is exemplified. The mud is soft because it has a high water content ratio, and is difficult to stack and transport on a dump truck or the like, and has fluidity that prevents people from walking on it. Therefore, it is difficult to reuse for civil engineering applications, and a technique for effectively utilizing mud is required.

  As such a technique, for example, as shown in Patent Documents 1 to 4, by adding a binding material such as blast furnace slag fine powder and an aggregate such as steelmaking slag to mud, A method for producing an artificial stone having the same strength has been proposed. Artificial stones manufactured in this way are used for harbor construction such as revetment, backfilling and landfilling, and sea area environmental restoration projects such as fish reefs.

JP 2011-93751 A JP 2011-93752 A JP 2011-246336 A JP 2012-12287 A

  The artificial stone obtained by the hydration reaction is cured, and the final strength is reached in about one month. However, when used for the above-mentioned applications, raw materials such as mud and steelmaking slag are hardened by putting them in pits of 10m to several tens of meters and then mixed, and then artificial stones during curing are appropriately specified. The size is divided into sizes (for example, a rectangular parallelepiped shape), transferred to another place, further cured, stored, and the like. Therefore, in order to divide the artificial stone in the course of curing, it is not necessary to reach the final strength, if it is cured to a strength that can be easily divided into a predetermined shape (hereinafter also referred to as initial strength). Good.

  However, even when the raw material composition is the same, there is a problem in that the strength of the artificial stone varies and the time to reach the initial strength is delayed (the solidification of the artificial stone is delayed). If the solidification of the artificial stone is delayed, the artificial stone cannot be transferred until the initial strength is reached, so that the production capacity of the artificial stone is reduced.

  The variation in strength tended to depend on the location where dredged soil used for mud was collected. Moreover, the solidification of the artificial stone tended to be delayed as the mixing ratio of the mud increased.

  This invention is made | formed in view of said situation, and it aims at providing the manufacturing method of the artificial stone which can express desired initial strength reliably in a short period of time.

  In order to solve the above problems, the present inventors have studied in detail the solidification mechanism of artificial stone, the alkali adsorption performance of the soil particles contained in the mud differs depending on the place where the mud is collected, After breaking through this alkali adsorption performance, by adding and mixing a binder that causes a hydration reaction, the strength of the artificial stone is reliably expressed, and the desired solidification can be achieved in a short period of time without delaying solidification. It was found that initial strength was obtained. Based on these findings, the present inventors have completed the present invention.

That is, the aspect of the present invention is
(1) After mixing mud and alkali supply material to obtain a preliminary mixture, the preliminary mixture and binder are mixed to obtain a mixture, and the mixture is hardened by a hydration reaction to artificial stone. It is the manufacturing method of the artificial stone characterized by obtaining.
(2) The method for producing an artificial stone according to (1), wherein the binder is blast furnace slag fine powder.
(3) The method for producing artificial stone according to (1) or (2), wherein the alkali supply material is steel slag.
(4) The method for producing an artificial stone according to any one of (1) to (3), wherein the alkali supply material is added at the time of mixing the preliminary mixture and the binder.
(5) The artificial stone manufacturing method according to any one of (1) to (4), wherein the content of the mud in the mixture is 40 vol% or more and 70 vol% or less.
(6) The method for producing an artificial stone according to any one of (1) to (5), wherein a moisture content of the mud is 70% or more and 250% or less.
(7) The method for producing an artificial stone according to any one of (1) to (6), wherein the mud is dredged soil.
(8) In any one of (1) to (7), the uniaxial compressive strength of the artificial stone after 10 days after obtaining the artificial stone is 5.0 N / mm ² or more. It is the manufacturing method of the described artificial stone.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the artificial stone which can express desired initial strength reliably in a short period can be provided.

FIG. 1 is a process diagram showing a manufacturing process of a method for manufacturing an artificial stone according to this embodiment. FIG. 2 is a diagram for explaining alkali adsorption characteristics of soil particles in the artificial stone manufacturing method according to the present embodiment. FIG. 3 is a graph showing the relationship between the location and time when the dredged soil was collected and the maximum amount of adsorbed alkali. FIG. 4 is a graph showing the relationship between the number of days for curing an artificial stone and the uniaxial compressive strength of the artificial stone for Examples and Comparative Examples of the present invention.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

(Manufacturing method of artificial stone)
In the method for producing an artificial stone according to the present embodiment, as shown in FIG. 1, first, mud and an alkali supply material are mixed to obtain a preliminary mixture. Thereafter, a binder is added to and mixed with the obtained preliminary mixture to obtain a mixture, and a hydration reaction is caused in the mixture to obtain an artificial stone in which the mixture is solidified. According to the manufacturing method of the artificial stone which concerns on this embodiment, desired initial intensity | strength can be achieved rapidly, without producing a solidification delay. Hereinafter, the manufacturing method of the artificial stone which concerns on this embodiment is demonstrated in detail.

(material)
As the raw material, mud, an alkali supply material and a binding material are used. Mud soil contains at least clayey soil particles and water, has a high water content ratio, is difficult to stack and transport on dump trucks, etc., and has fluidity that prevents people from walking on it Is shown. As a specific water content ratio, in the present embodiment, it is preferably 70 to 250%. The water content ratio of the mud is determined from the mass ratio (water / soil particles) of water and soil particles contained in the mud.

  Examples of mud include dredged soil and construction soil. Dredged soil is generally generated by dredging, including the purpose of expanding the routes and anchorage of ports, rivers, canals, etc., and the purpose of removing sludge and sediment from the bottom of the river, lakes, dams, etc. It is. Construction soil is soil discharged by construction work such as excavation.

  The alkali supply material is a raw material that supplies an alkaline component to the mud and the binder described later. In the premixing, an alkali component is supplied in order to break through the alkali adsorption ability of the soil particles contained in the mud.

  Examples of the alkali supply material include steelmaking slag, slaked lime, cement and the like. In this embodiment, steelmaking slag is used. Steelmaking slag is one of converter slag, pretreatment slag, decarburization slag, dephosphorization slag, desulfurization slag, desiliconization slag, electric furnace reduction slag, electric furnace oxidation slag, secondary refining slag, ingot slag, etc. What mixed 1 type (s) or 2 or more types can be used.

  The one where the particle size of an alkali supply material is fine is preferable. This is because as the surface area of the alkali supply material is larger, the alkali adsorption of the soil particles contained in the mud is promoted. In this embodiment, it is preferable that the particle size of the alkali supply material is 5 mm or less.

Examples of the binding material include blast furnace slag fine powder and various cements. Among them, fine powder of blast furnace slag is obtained by finely pulverizing blast furnace slag obtained by separating and recovering components other than iron together with ash in coke and other ingredients in iron ore melted in the blast furnace that produces pig iron. can get. Specifically, it is obtained by finely pulverizing granulated slag that has been rapidly cooled by, for example, injecting pressurized water into the molten slag. The specific surface area of the granulated slag fine powder is generally about 3000 to 8000 cm ² / g. Blast furnace slag fine powder is mixed with Portland cement and used as an AC type blast furnace slag cement, but it alone has latent hydraulic properties and takes time to cure. Therefore, the present invention is suitable for the present invention.

(Manufacturing process)
As shown in FIG. 1, in this embodiment, without adding a binder, first, mud and an alkali supply material are mixed to obtain a preliminary mixture. By doing in this way, the alkali adsorption ability which the mud soil particles have can be broken through.

As shown in FIG. 2, the clayey soil particles contained in the mud soil are negatively charged on the surface and adsorb cations (H ⁺ , Mg ²⁺ , Al ^3+, etc.). At this time, when it comes into contact with ionic components (Ca ²⁺ , OH ⁻ ) of water containing an alkaline component eluted from the alkali supply material, among the cations adsorbed on the surface, cations having a smaller affinity than Ca ²⁺ , Ca ²⁺ is ion-exchanged, and Ca ²⁺ is adsorbed. The dissociated OH ⁻ is consumed by a neutralization reaction (H ⁺ + OH ⁻ → H ₂ O) or a hydroxide precipitation reaction (Mg ²⁺ + 2OH ⁻ → Mg (OH) ₂ ).

  Conventionally, when man-made stones are produced by mixing mud, steelmaking slag and blast furnace slag fine powder, the order of mixing these raw materials is not particularly considered, and blast furnace slag fine powder which is mud and binder After mixing, steelmaking slag was generally added for alkali stimulation. In order to cause a hydration reaction that causes solidification, first, the mud containing moisture is mixed with a binder such as blast furnace slag fine powder containing amorphous substances such as Si and Al that cause the hydration reaction. Seems to have been considered preferable.

  However, when steelmaking slag is added to the mixture of mud and ground granulated blast furnace slag, the alkaline components supplied from the steelmaking slag are consumed preferentially for the mud's alkali adsorption. Until then, the alkali stimulation that promotes solidification by the hydration reaction is not sufficient, so there is a disadvantage that the solidification delay occurs and the time to reach the initial strength that can be taken out becomes long, and the production efficiency decreases. .

  In addition, the alkali adsorption characteristics described above vary depending on the mud, and, for example, the dredged soil varies depending on the sampling location, the sampling time, and the like. FIG. 3 shows the measurement results of the alkali adsorption capacity at the place where the dredged material was collected. As is clear from FIG. 3, the maximum alkali adsorption amount differs by about 3 to 4 times depending on the place where the dredged soil was collected, and also at the point E, there is a difference due to the difference in the collection time.

  Due to the difference in alkali adsorption characteristics, even if the same amount of steelmaking slag and ground granulated blast furnace slag is blended with mud such as dredged soil at different sampling locations or times, the alkaline adsorption performance of dredged soil will break through. Since the amount of alkali components required by the time differs depending on the clay, the time when alkali stimulation starts to work effectively varies. As a result, the degree to which solidification is promoted is also different, and it is considered that variation occurs in a period until a desired initial strength is developed.

  Therefore, in the present embodiment, as described above, first, mud and alkali supply material are mixed to form a preliminary mixture, thereby quickly breaking through the mud's alkali adsorption ability as shown in FIG. I made it. And after the alkali adsorption ability of the mud in the preliminary mixture breaks through, a binder is added and mixed to obtain a mixture. In this mixture, the alkali supply from the alkali supply material is consumed for alkali stimulation for the hydration reaction of the ground granulated blast furnace slag without being consumed for the alkali adsorption of the mud. As a result, the solidification reaction of the mixture is promoted, and an artificial stone having a desired initial strength can be obtained quickly. In addition, it is possible to suppress variations in the period until the initial strength due to the difference in alkali adsorption ability is reached.

  The content ratio of the mud in the mixture obtained by mixing the preliminary mixture and the binder is preferably 40 vol% or more and 70 vol% or less in volume ratio. Since the curing period until reaching the initial strength tends to increase as the content ratio of the mud increases, the effect obtained by the present invention increases when the content ratio of the mud is 40 vol% or more. When the content ratio of the mud exceeds 70 vol%, the content ratios of the alkali supply material and the binder are decreased, and the strength required for the artificial stone may not be obtained.

  It is preferable that the content rate of the alkali supply material in said mixture is 10 vol% or more and 50 vol% or less by volume ratio. When the content ratio of the alkali supply material is less than 10 vol%, the action as an alkali stimulant for wave surplus and blast furnace slag fine powder tends to be insufficient, and when it exceeds 50 vol%, the steelmaking slag expands due to hardening, The strength required for artificial stones may not be obtained.

  The content ratio of the binder in the above mixture is preferably 15 vol% or more and 50 vol% or less in volume ratio. If the content of the binder is less than 15 vol%, the bond strength tends to be insufficient, and if it exceeds 50 vol%, the strength of the artificial stone may be saturated.

  In addition to the water contained in the mud, water is added to the above mixture for the purpose of adjusting the moisture content of the mud, ensuring the fluidity of the mixture, ensuring workability when pouring the mixture into a mold, etc. May be. In this case, it is preferable that the water content ratio of the mud determined from the total amount of the water contained in the mud and the added water is within the above-described range.

  The mixing method in the preliminary mixing is not particularly limited. Commercially available mixers may be used, and when artificial stones are produced efficiently in large quantities, raw materials can be introduced into pits of several tens of meters and mixed using a shovel car or the like. In addition, the mixing time of the mud and the alkali supply material in the preliminary mixing is affected by the difference between the mixing amount at the laboratory level and the mixing amount at the actual machine level, but is not particularly limited as long as it is uniformly mixed. . For example, with a biaxial forced kneading mixer, it is usually sufficient if it is about 90 seconds or longer.

  Also in the case of obtaining a mixture by mixing the premix and the binder, the mixing method and time in the premix can be applied.

  It should be noted that moisture is added for the purpose of adjusting the moisture content of the mud, ensuring fluidity of the mixture, ensuring workability when pouring the mixture into a mold, etc. during either or both of premixing and mixing. It may be added.

(Artificial stone)
The artificial stone that has reached the initial strength is divided into a predetermined shape as needed, or transported to another place, and further cured until the final strength is reached. The artificial stone produced by the above-described method can exhibit a desired initial strength by curing for a short time. Since artificial stones may be piled up and cured, stored, etc., in this embodiment, the uniaxial compressive strength after curing for 10 days is preferably 5.0 N / mm ² or more.

Further, as the final strength of the artificial stone after completion of curing, the uniaxial compressive strength is preferably 9.8 N / mm ² or more.

  The shape is not particularly limited, and may be determined as appropriate according to the application. When used for port construction, sea area environment improvement construction, etc., for example, it is shaped like a rectangular parallelepiped and has a weight of about several hundred kg per piece.

(Effect of this embodiment)
In this embodiment, the mixing order of the mud, the binder, and the alkali supply material is clearly defined. That is, first, mud and alkali supply material are premixed to obtain a premix. In this preliminary mixture, the alkali component supplied from the alkali supply material is ion-exchanged with cations adsorbed on the soil particle surface of the mud, and the alkali component is adsorbed on the soil particle surface. As this reaction proceeds, the alkali adsorption ability of the mud soil particles contained in the premix is broken through.

  Subsequently, a binder is added to and mixed with the premix to obtain a mixture. When a binder is added, a hydration reaction occurs in the mixture, but the alkali component supplied from the alkali supplier is not consumed for alkali adsorption of the soil particles, and sufficient alkali stimulation is ensured on the binder. Therefore, solidification by hydration reaction is promptly promoted.

  As a result, since the solidification delay due to the alkali adsorption of the soil particles does not occur, the initial strength can be expressed quickly. Therefore, the production efficiency of artificial stone can be increased.

  Furthermore, although the alkali adsorption capacity of the soil particles varies depending on the place where the mud was collected, the alkali adsorption capacity is broken through during premixing, so even if the alkali adsorption capacity is different, the mixing of the premix and the binder Sometimes alkali stimulation occurs uniformly, so that variations in strength expression can be absorbed.

(Modification)
In the above-described embodiment, the alkali supply material blended at the time of the premixing supplies the alkali component so as to break through the alkali adsorption ability of the soil particles, and is further added in the mixing of the premixture and the bonding material. An alkali component is supplied so that alkali stimulation sufficiently occurs. In other words, the alkali supply material blended at the time of premixing has an alkali component amount sufficient to break through the alkali adsorption ability of the soil particles and cause alkali stimulation to the binder.

  However, the alkali supply material blended at the time of the premixing only needs to have a minimum amount of alkali components that can break through the alkali adsorption ability of the soil particles, and at the time of mixing the premix and the binder, You may further add the alkali supply material which has the amount of alkali components required to produce irritation. That is, an alkali supply material may be additionally added when mixing the premix and the binder. Also in this case, the same effect as the above-described embodiment can be obtained.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.

(Example)
As mud, dredged soil (water content 97%, wet density 1.32 g / cm ³ ) collected by dredging at a harbor was used. As the alkali supply material, steel slag collected at the Oita Works and having a density of 2.88 g / cm ³ and a particle size of 5 mm or less was used. As a binder, blast furnace slag fine powder 4000 (specific surface area 4000 cm ² / g) for concrete defined in JIS A 6206 was used.
Table 1 shows the properties of the clay, the steelmaking slag and the blast furnace slag fine powder, and the properties and ratios of these mixtures.

  First, clay and steelmaking slag were mixed for 120 seconds using a biaxial forced kneading mixer to obtain a preliminary mixture. After taking an hour for breakthrough from the separately measured alkali adsorption capacity test, add blast furnace slag fine powder and a predetermined amount of seawater to the obtained preliminary mixture and use a biaxial forced kneading mixer. Mix for 120 seconds to obtain a mixture. As shown in Table 1, in the obtained mixture, the volume ratio of the clay was 60.0 vol%, the volume ratio of the steelmaking slag was 11.9 vol%, and the volume ratio of the blast furnace slag fine powder was 22.6 vol%. .

  This mixture was packed into a mold and molded, and this was cured for 10 days under humid conditions at a temperature of 20 ° C. to obtain a test artificial stone of φ50 mm × height 100 mm. About the obtained artificial stone for a test, the uniaxial compressive strength was measured using the 1000 kN pressure | voltage resistant compression tester, when the 5th and 10th day passed from the start of curing. The results are shown in Table 2 and FIG.

(Comparative example)
As a comparative example, using the clay, steelmaking slag and blast furnace slag fine powder of the example, a mixture was obtained in the following order of mixing. In the comparative example, first, clay, blast furnace slag fine powder, and a predetermined amount of seawater were mixed for 120 seconds using a biaxial forced kneading mixer to obtain a preliminary mixture. Immediately thereafter, steelmaking slag was added to the obtained preliminary mixture and mixed for 120 seconds using a biaxial forced kneading mixer to obtain a mixture. As shown in Table 1, in the obtained mixture, the volume ratio of the clay is 60 vol%, the volume ratio of the steelmaking slag is 11.9 vol%, and the volume ratio of the blast furnace slag fine powder is 22.6 vol%, which is exactly the same as the example. The only difference is that after mixing the blast furnace slag fine powder, the order of adding the steelmaking slag and the time for breakthrough were taken.

  The obtained mixture was molded and cured in the same manner as in the example to prepare a test artificial stone, and the compressive strength was measured by the same method as in the example until the curing period of 45 days. About the obtained artificial stone for a test, the uniaxial compressive strength was measured using the 1000kN pressure | voltage resistant test machine when 6th, 12th, 38th, and 45th passed since the curing start. The results are shown in Table 2 and FIG.

From Table 2 and FIG. 4, in the example, the uniaxial compressive strength rapidly increased, and on the 10th day, the uniaxial compressive strength exceeded 6 N / mm ² and was strong enough to be easily divided into predetermined shapes (initial value). Strength). On the other hand, in the comparative example, the composition and the properties immediately after mixing are the same, and the curing period exceeds 10 days, even though the mixing order is different, and the compressive strength is also at the time of 12 days. It stayed at 0.15 N / mm ² , and the uniaxial compressive strength hardly increased. This is because, in the comparative example, the alkali component supplied from the steelmaking slag was preferentially used for the alkali adsorption of the clay particles of the clay, the alkali stimulation to the blast furnace slag fine powder was not sufficient, and the solidification delay occurred. Inferred.

  Regarding the final strength, it is considered that there is no difference between the example and the comparative example, but the curing period required to achieve the initial strength that can be carried out is about 5 days in the example, In the comparative example, it took about one month, and it was confirmed that there was a large difference. Therefore, the employment efficiency of the artificial stone can be remarkably improved by employing the present invention.

Claims (8)

  Mixing mud and alkali supply material to obtain a pre-mixture, and then mixing the pre-mixture and binder to obtain a mixture, and curing the mixture by hydration reaction to obtain an artificial stone An artificial stone manufacturing method characterized by the above.   The method for producing an artificial stone according to claim 1, wherein the binder is blast furnace slag fine powder.   The method for producing an artificial stone according to claim 1, wherein the alkali supply material is steel slag.   The method for producing an artificial stone according to any one of claims 1 to 3, wherein the alkali supply material is additionally added when the preliminary mixture and the binder are mixed.   The method for producing an artificial stone according to any one of claims 1 to 4, wherein a content ratio of the mud in the mixture is 40 vol% or more and 70 vol% or less.   The method for producing artificial stone according to any one of claims 1 to 5, wherein a moisture content of the mud is 70% or more and 250% or less.   The method for producing an artificial stone according to any one of claims 1 to 6, wherein the mud is dredged clay. 8. The artificial material according to claim 1, wherein the artificial stone has a uniaxial compressive strength of 5.0 N / mm ² or more at a curing period of 10 days after obtaining the artificial stone. Stone manufacturing method.