WO2011136395A1

WO2011136395A1 - Method for producing artificial stone material

Info

Publication number: WO2011136395A1
Application number: PCT/JP2011/060801
Authority: WO
Inventors: 高橋　克則; 渡辺　圭児; 薮田　和哉; 本田　秀樹; 林　正宏; 松本　剛; 操鈴木; 靖史林堂
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2010-04-30
Filing date: 2011-04-28
Publication date: 2011-11-03

Abstract

Disclosed is a method for stably producing an artificial stone material having a strength equal to or higher than a semi-hard stone using large amounts of mud such as dredged spoil. When producing the artificial stone material by hydration hardening of a mixed material containing mud and a binder, the mixed material satisfies the following conditions (a)-(c). (a) The mixed material contains 40 percent by volume or more of mud per 100 percent by volume of the mixed material. (b) The binder is composed of at least one component selected from a group consisting of blast furnace slag micropowder, blast furnace slag micropowder added with an alkaline stimulant, portland blast furnace slag cement, and ordinary portland cement. (c) The amount of the binder has a mass ratio of 1.7 times or more relative to soil particles (solid content) in the mud, and satisfies (mass of the blast furnace slag micropowder + mass of lime powder + mass of hydrated lime + mass of ordinary portland cement ×2)/(mass of water in the mixed material)<2.0, and when further blending fly ash as a part of the binder, satisfies (mass of the blast furnace slag micropowder + mass of lime powder + mass of hydrated lime + mass of ordinary portland cement ×2 + mass of fly ash ×0.35)/(mass of water in the mixed material)≤1.5.

Description

Manufacturing method of artificial stone

The present invention relates to a method for producing artificial stone by solidifying mud such as clay with a binder.

Soft mud, represented by dredged soil, is generated with the construction of channel dredging and various civil engineering works. Among them, those useful as civil engineering materials such as sand can be used as they are for the construction of shallow fields and backfilling. However, mud with a high ratio of silt is often in a water-containing state, and since it can hardly be expected to have strength as soil, it often becomes waste.
Various techniques have been proposed and implemented for effective use of mud. The most representative one is a technique for improving the characteristics of soil and using it in the same way as high-quality soil. For example, “Stable treatment method for soft ground with lime” by the Japan Lime Association (Kashima Publishing Co., Ltd.) shows various techniques for improving the properties of the ground by adding cement and lime to mud.

Patent Document 1 discloses a technique for improving strength by mixing steel slag with clay. In this technique, the strength of the clay is improved mainly by a pozzolanic reaction between the CaO content of the steel slag and Si, Al, etc. of the clay. Patent Document 2 discloses a technique for performing solidification treatment (improvement of strength) by adding converter slag containing free CaO and blast furnace cement to soft soil.
However, these methods are improvement of characteristics as a soil material, and although the strength of the soil material level is expressed, it is limited to the use as soil.
On the other hand, Patent Document 3 discloses a method of obtaining a block material (solidified body) by mixing a solidified material such as cement with clay and solidifying it.

JP 2009-121167 A Japanese Patent Laid-Open No. 2006-231208 JP 2008-182898 A

However, the strength of the block material obtained by the method of Patent Document 3 is on average at a 6N / mm ² approximately, only about 8N / mm ² at most. Here, in order to use it as a substitute for stone or concrete material, strength (9.8 N / mm ² or more) higher than the semi-hard stone specified in JIS-A-5006: 1995 (split stone) is required. . The strength of the block material obtained in Patent Document 3 is the lowest quality soft stone level (less than 9.8 N / mm ² ). Although the level of soft stone is considerably higher than the improvement level of soil materials, it is not strong enough to be used for various purposes as an alternative to stone and concrete materials. Further, when a large amount of mud having a high silt content (75 μm or less), which is often seen in soft dredged soil, is used, it is easily expected that securing strength becomes more difficult.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, use a large amount of mud such as dredged soil, and have a strength higher than that of semi-hard stone, especially a safety factor (+3 N / mm ² ). An object of the present invention is to provide a production method capable of stably producing an artificial stone material that sufficiently satisfies the characteristics of quasi-hard stone even when considered.

Conventionally, manufacturing technology of steel slag hydrated solidified body using steel slag as a main raw material is known (for example, “Steel Slag Hydrated Solidified Body Technical Manual”, Coastal Technology Research Center). In this technique, a steel slag is used as an aggregate, and a blast furnace slag fine powder and an alkali stimulant are used as a binder, and a hydrated solid body is produced. The inventors of the present invention conducted a production experiment of a solidified body in which the material of the hydrated solidified body of steel slag was replaced with clay based on the production technology of the hydrated solidified body of steel slag.

Strength index = (mass of ground granulated blast furnace slag + mass of slaked lime + 2 × mass of ordinary Portland cement + 0.35 × mass of fly ash) / water as an index representing the degree of strength development of hydrated solidified steel slag Mass is used. In the production of a hydrated and solidified steel slag, kneading is performed when the strength index exceeds 2 in order to develop a stable strength. Since it was thought that securing strength was important even when using clay as in the present invention, the ratio of water and binder contained in the clay was set and kneaded so as to satisfy the strength index according to the above. Carried out. However, in this test, it was found that the fluidity of the kneaded material was drastically reduced, and as a result, voids entered during casting, the hydrated solidified body became brittle, and the strength was not sufficiently developed. . That is, it was thought that the strength would be difficult to develop by mixing the clay, so the ratio of the binder and water was maintained at the conventional level of knowledge (production technology for hydrated solidified steel slag), but appropriate kneading・ It was found that it was difficult to manufacture artificial stones and blocks made of clay as raw materials with conventional manufacturing techniques that could not be placed.

Therefore, in order to improve the fluidity of the kneaded material, the present inventors adjust the water content by further adding water to the clay originally holding water, while reducing the ratio of the binder and water to some extent. The conditions for kneading were examined. As a result, depending on the conditions, the strength may be exhibited in some cases, but it was also found that sufficient strength may not be obtained even with a relatively close blending. As a result of further examination of this cause, mud soil typified by dredged soil may inhibit the pozzolanic reaction due to surface adsorption of the soil particles, and when trying to use a large amount of dredged soil, It was found that the inhibition of pozzolanic reaction by surface adsorption had a great influence on the strength development.

It was found that dredged soil has an action of adsorbing Ca ²⁺ and OH ⁻ , although the degree varies depending on the type of soil. FIGS. 1 (a) and 1 (b) show examples of changes in the concentration of Ca and pH when a calcium hydroxide solution is permeated through dredged soil collected from the Tamagawa River and dredged soil collected from Tokyo Bay. In this test, 2 g of clay was filled in a permeation tube with filter paper on the bottom, and a calcium hydroxide aqueous solution adjusted to pH 12 was added dropwise at 1 mL / min to recover the leached solution. The Ca concentration and OH ⁻ concentration were measured. According to FIG. 1, it can be seen that the Ca concentration and OH ⁻ concentration (pH) of the solution change greatly only by permeating the clay. Ca ²⁺ and OH ⁻ are main components of a reaction product (CaO—SiO ₂ —H ₂ O gel) at the time of hydration solidification represented by cement. It is considered that Ca ²⁺ and OH ⁻ are adsorbed on the soil particles of the clay and the concentration is lowered, so that the solidification is inhibited. Such an adsorption action of Ca ²⁺ and OH ⁻ is peculiar when mud such as dredged soil is used, and was not conscious at all in a normal steel slag hydrated solid body containing no mud as a material. . As a result of repeated studies to solve such problems, the mass ratio of the binder to the soil particles in the mud is set to a predetermined value or more, and the water / binder ratio is a conventional technology for producing hydrated solidified steel slag. It was found that a solidified body (stone) having a stable strength can be obtained by using a large amount of mud such as dredged soil by optimizing it in a different range.

The present invention has been made on the basis of such findings and has the following gist.
[1] A method for producing an artificial stone material by hydrating and hardening a mixed material containing mud and a binder, wherein the mixed material satisfies the following conditions (a) to (c): Production method.
(A) Contains 40 volume% or more of mud.
(B) For 100% by volume of the mixed material, the binder comprises at least one selected from blast furnace slag fine powder, blast furnace slag fine powder to which an alkali stimulant is added, blast furnace cement, and ordinary Portland cement.
(C) The amount of the binder is 1.7 times or more by mass ratio with respect to the soil particles (solid content) in the mud and satisfies the following formula.
(Mass of blast furnace slag fine powder + Mass of lime powder + Mass of slaked lime + Mass of ordinary Portland cement × 2) / (Mass of water in mixed material) <2.0
[2] In the production method of [1], the binder contains 80 to 95% by mass of blast furnace slag fine powder, and the balance is one or more selected from ordinary Portland cement, lime powder, slaked lime, and blast furnace cement. A method for producing an artificial stone, characterized in that

[3] A method for producing an artificial stone material by hydrating and hardening a mixed material containing mud and a binder, wherein the mixed material satisfies the following conditions (d) to (f): Production method.
(D) Containing 40 volume% or more of mud with respect to 100 volume% of mixed materials.
(E) The binder comprises at least one selected from blast furnace slag fine powder, blast furnace slag fine powder to which an alkali stimulant is added, blast furnace cement, and ordinary Portland cement, and fly ash.
(F) The amount of the binder is 1.7 times or more by mass ratio with respect to the soil particles (solid content) in the mud and satisfies the following formula.
(Mass of blast furnace slag fine powder + Mass of lime powder + Mass of slaked lime + Mass of ordinary Portland cement × 2 + Mass of fly ash × 0.35) / (Mass of water in mixed material) ≦ 1.5

[4] In the production method of [3], the binder contains 70 to 85% by mass of blast furnace slag fine powder, and fly ash is contained in an amount of 10 to 30% by mass relative to the mass of the blast furnace slag fine powder. A method for producing an artificial stone, wherein the balance is at least one selected from ordinary Portland cement, lime powder, slaked lime, and blast furnace cement.
[5] The method for producing an artificial stone material according to any one of the above [1] to [4], wherein the mixed material further contains an aggregate.
[6] The method for producing an artificial stone material according to [5], wherein the aggregate is steel slag.
[7] The method for producing an artificial stone material according to [6], wherein the blending amount of the steelmaking slag per unit volume in the mixed material is 700 kg / m ³ or more.
[8] The method for producing an artificial stone material according to any one of the above [1] to [7], wherein the mud contains 65% by volume or more of particles having a particle size of 0.075 mm or less.
[9] In the manufacturing method according to any one of [1] to [8] above, the mud is dredged material generated by dredging work, and the dredged material is temporarily stored in the dredging yard and stored in the dredging yard. A method for producing an artificial stone material comprising producing an artificial stone material using mud clay.

According to the present invention, an artificial stone material having a strength equal to or higher than that of semi-hard stone can be stably produced by using a large amount of mud such as clay.

FIG. 1 is a graph showing an example of changes in solution Ca concentration and pH when a calcium hydroxide solution is permeated through the clay. Fig. 2 shows the mass ratio of the binder compounded in the mixed material and the soil particles (solid content) in the mud [binding material / soil particles in the mud] and the strength of the solidified body (uniaxial compressive strength after 28 days of curing) It is a graph which shows the relationship. FIG. 3 shows the strength index B / water (= [mass of blast furnace slag fine powder + mass of lime powder + mass of slaked lime) + mass of ordinary Portland cement × 2 + fry of the mixed material containing fly ash as a part of the binder. It is a graph which shows the relationship between the mass of ash x 0.35] / [the mass of water in the mixed material]) and the slump value. FIG. 4 is a graph showing the relationship between the curing period and the strength of the solidified body (uniaxial compressive strength). FIG. 5 is a diagram for explaining an embodiment of the present invention using a dredging site.

The present invention is a method for producing an artificial stone material by kneading a mixed material containing mud and a binder, more preferably an aggregate, and hydrating and hardening (solidifying the binder by a hydration reaction). Satisfies the following conditions (a) to (c).
(A) Contains 40 volume% or more of mud.
(B) The binder comprises at least one selected from blast furnace slag fine powder, blast furnace slag fine powder to which an alkali stimulant is added, blast furnace cement, and ordinary Portland cement.
(C) The amount of the binder is 1.7 times or more by mass ratio with respect to the soil particles (solid content) in the mud and satisfies the following formula.
(Mass of blast furnace slag fine powder + Mass of lime powder + Mass of slaked lime + Mass of ordinary Portland cement × 2) / (Mass of water in mixed material) <2.0

Further, fly ash can be further blended as the binder, and in this case, the mixed material satisfies the following conditions (d) to (f).
(D) Contains 40% by volume or more of mud.
(E) The binder comprises at least one selected from blast furnace slag fine powder, blast furnace slag fine powder to which an alkali stimulant is added, blast furnace cement, and ordinary Portland cement, and fly ash.
(F) The amount of the binder is 1.7 times or more by mass ratio with respect to the soil particles (solid content) in the mud and satisfies the following formula.
(Mass of blast furnace slag fine powder + Mass of lime powder + Mass of slaked lime + Mass of ordinary Portland cement × 2 + Mass of fly ash × 0.35) / (Mass of water in mixed material) ≦ 1.5

The mud used in the present invention is typically dredged, but other examples include mud generated from excavation work and construction sludge. Here, the muddy soil generally refers to a material that cannot be piled up and exhibits fluidity that prevents people from walking on it. As an approximate strength, the cone index defined by JIS-A-1228: 2009 (cone index test method for compacted soil) is 200 N / mm ² or less.
The production method according to the present invention is particularly useful because mud soil typified by dredged material has a higher ion adsorption effect as the silt content is larger, and it becomes difficult to obtain a solidified body having an appropriate strength with the conventional technology. Specifically, it can be said that the present invention is particularly useful when a mud soil containing 65 volume% or more of soil particles (silt content) having a particle size of 0.075 mm or less is targeted.
In the following description, the term “silt” of mud refers to soil particles having a particle size of 0.075 mm or less.

The purpose of the present invention is to effectively utilize mud represented by dredged soil, and therefore it is preferable that the proportion of mud in the mixed material is as large as possible. Therefore, the proportion of mud in the mixed material (originally mud The ratio of the water content contained in is 40% by volume or more. The upper limit of the proportion of mud is not particularly limited, but if the proportion of dredged soil is 60% by volume or less, the relative amount of steelmaking slag becomes an appropriate amount, and the specific gravity of the solidified body greatly increases to 2.0. Never fall below. If the specific gravity is not significantly lower than 2.0, it has utility as a stone substitute. Therefore, the proportion of mud in the mixed material is desirably 60% by volume or less.

Examples of the binder include blast furnace slag fine powder, blast furnace slag fine powder to which an alkali stimulant is added, blast furnace cement, and ordinary Portland cement, and one or more of these can be used.
From the viewpoint of reducing the environmental load without using natural materials as much as possible, and from the viewpoint of securing the strength of the artificial stone material (hereinafter sometimes referred to as “solidified body”) and the manufacturing cost, What added the alkali stimulant to the blast furnace slag fine powder is desirable. By using an alkali stimulator together with the blast furnace slag fine powder as a binder, an alkaline environment can be created, and thereby the hydraulic properties of the blast furnace slag fine powder can be exhibited. That is, the hydration reaction of the blast furnace slag fine powder can be promoted, and the strength of the solidified body can be ensured.

As the alkali stimulating agent, for example, one or more kinds of lime powder, slaked lime, ordinary Portland cement, blast furnace cement and the like can be used. In this case, it is preferable that 80 to 95% by mass of blast furnace slag fine powder is contained, and the balance is one or more selected from lime powder, slaked lime, ordinary Portland cement, and blast furnace cement. When an alkali stimulant is used together with the blast furnace slag fine powder as a binder, if the proportion of the blast furnace slag fine powder is 80% by mass or more, an excess alkali component does not remain in the solidified body. For this reason, when using a solidified body in the sea etc., the load of the alkali with respect to seawater environment is small. It is also economically advantageous. On the other hand, it is possible to knead and solidify even if the ratio of the blast furnace slag fine powder exceeds 95% by mass. However, if it is 95% by mass or less, it is easy to stably disperse, and since the effect of the stimulant is reduced due to the alkali suppression effect of the clay, the effect of adding blast furnace slag fine powder is effective. It is expensive and does not require the use of various raw materials and does not impose equipment load, so it has economic validity.

Since mud such as dredged soil has an adsorption action of Ca ²⁺ and OH ⁻ as shown in FIG. 1, the amount of the soil particles may greatly affect the adsorption amount of Ca ²⁺ and OH ⁻ . In the case of solidification by gelation such as cement, it was considered important to form a gel network. Therefore, the factors involved in strength development were examined while changing the balance between the clay and the binder. As a result, it was found that the amount of the binder and the ratio of the soil particles contained in the dredged material have a great influence on the strength.
The relationship between the mass ratio of the binder compounded in the mixed material and the soil particles (solid content) in the mud [the binder / soil particles in the mud] and the strength of the solidified body (uniaxial compressive strength after 28 days of curing) The result of the examination is shown in FIG. In this test, clay with a silt content of 90% by volume was used as mud, blast furnace slag fine powder was mainly used as a binder, and slaked lime and ordinary Portland cement were used as alkali stimulants. The ratio of the amount of binder in the mixed material to water is (mass of blast furnace slag fine powder + mass of lime powder + mass of slaked lime + mass of ordinary Portland cement × 2) / (mass of water in the mixed material) ) <2.0.

According to FIG. 2, it can be seen that in order to ensure the strength of the solidified body, a certain amount or more of binding material is necessary with respect to the amount of mud soil particles. As the strength of the solidified body, there is no essential problem as long as it can clear the required strength level of quasi-hard stone of 9.8 N / mm ² or more. However, in consideration of variations in dredged soil and manufacturing variations, it is necessary for ensuring the quality that the target strength has a strength margin of about 3 N / mm ² as in the case of ready-mixed concrete. Specifically, if [binding material / soil particles in mud] ≧ 1.7, it can be seen that the uniaxial compressive strength after curing for 28 days can be about 15 N / mm ² with a strength margin. For this reason, the amount of the binder in the mixed material is 1.7 times or more by mass ratio with respect to the soil particles (solid content) in the mud. Moreover, it is more preferable that the mass ratio is 2.2 times or more because stable strength can be expected even if the clay is uneven.

On the other hand, when the amount of the binding material is simply increased, the amount of the binding material becomes too much with respect to water, and on the contrary, strength reduction and poor filling are likely to occur. About the ratio of the water and the binder in the mixed material, the strength index according to the strength index used in the steel slag hydrated solidified body, that is, (mass of blast furnace slag fine powder + mass of lime powder + slaked lime Mass + normal Portland cement mass x 2) / (mass of water in the mixed material). Since blast furnace cement is a mixture of blast furnace slag fine powder and ordinary Portland cement, the mass corresponding to the mixing ratio of the blast furnace slag fine powder of the blast furnace cement is referred to as “mass of blast furnace slag fine powder”, and ordinary Portland cement of blast furnace cement is used. The above formula is applied with the mass corresponding to the mixing ratio of the particles as “mass of ordinary Portland cement”.

In the case of steel slag hydrated solidified material, the mixing ratio of the binder and water is designed so that the strength index is 1.5 or more, and the condition exceeding 2.0 is general (“steel slag See "Hydro-solidified technical manual"). On the other hand, it was found that completely different conditions were necessary when using clay. Water content ratio of dredged soil 220% (water content ratio = ([moisture content of dredged soil (mass%)] / [solid content of dredged soil (mass%)]) × 100), relative volume ratio of dredged soil 50% Table 1 shows the results of examining the relationship between the strength index of the mixed material kneaded under sufficient water conditions and the strength of the obtained solidified body (uniaxial compressive strength after 28-day curing). According to this, although the strength increases as the strength index increases (that is, the ratio of the binder to water increases), it reaches a peak at about 1.95, and the kneading failure occurs under a condition exceeding 2.3. From the above results, the amount of the binder is less than 2.0 (mass of blast furnace slag fine powder + mass of lime powder + mass of slaked lime + mass of ordinary Portland cement × 2) / (mass of water in the mixed material). , Preferably 1.95 or less.

As the binder, fly ash can be further blended. For example, as described later, when steelmaking slag is blended in the mixed material as an aggregate, a large amount of Ca may be contained in the steelmaking slag, so that the alkali content may be excessive. Since the clay is mainly composed of SiO ₂ , it can be stabilized by a hydration reaction with excess alkali. However, the mineral phase that constitutes the solid particles of dredged soil varies depending on dredged areas and occurrence history, so the reactivity may not be stable. In such a case, the fly ash is blended as a part of the binder, that is, selected from blast furnace slag fine powder, blast furnace slag fine powder added with an alkali stimulant, blast furnace cement, and ordinary Portland cement. It is desirable to use fly ash in combination with more than seeds.

Since the composition of fly ash is mainly composed of amorphous SiO ₂ and Al ₂ O ₃ , it can be expected that a pozzolanic reaction will occur more quickly than the crystalline material when an excessive alkali content is generated. . However, when fly ash is added excessively, the amount of Ca in the binder becomes too small, and the stability of the reaction, which is the original role, may be impaired. From this point of view, when fly ash is blended, it is a ratio to the total of one or more selected from blast furnace slag fine powder, blast furnace slag fine powder added with an alkali stimulant, blast furnace cement, and ordinary Portland cement. It is preferable that the upper limit is about 40% by mass.

Also, as mentioned above, the binder added to the mixed material is particularly preferably a blast furnace slag fine powder added with an alkali stimulant. When fly ash is used in combination with such a binder, the blast furnace slag fine powder is contained in an amount of 70 to 85% by mass and the fly ash is contained in an amount of 10 to 30% by mass with respect to the mass of the blast furnace slag fine powder. The balance is preferably at least one selected from ordinary Portland cement, lime powder, slaked lime, and blast furnace cement. The reason why the blast furnace slag fine powder is blended in the above range is basically the same as the reason described above. However, since fly ash is used in combination, the blending ratio of the blast furnace slag fine powder is relatively reduced. Further, as described above, when fly ash is added excessively, the amount of Ca in the binder becomes too small, and the stability of the reaction, which is the original role, may be impaired. For this reason, the blending amount of fly ash is preferably about 30% by mass with respect to the mass of the blast furnace slag fine powder. On the other hand, in order to obtain the effect of blending fly ash, the lower limit is preferably about 10% by mass with respect to the mass of the blast furnace slag fine powder.

Further, when fly ash is blended as a part of the binder, the ratio of water and binder in the mixed material is a strength index according to the strength index used in the steel slag hydrated solidified body, that is, It was found that (mass of blast furnace slag fine powder + mass of lime powder + mass of slaked lime + mass of ordinary Portland cement × 2 + mass of fly ash × 0.35) / (mass of water in the mixed material). Since blast furnace cement is a mixture of blast furnace slag fine powder and ordinary Portland cement, the mass corresponding to the mixing ratio of the blast furnace slag fine powder of the blast furnace cement is referred to as “mass of blast furnace slag fine powder”, and ordinary Portland cement of blast furnace cement is used. The above formula is applied with the mass corresponding to the mixing ratio of the particles as “mass of ordinary Portland cement”.

As described above, the strength of the solidified body when fly ash is not blended as a binder is peaked at a strength index of 1.95, and kneading is poor at 2.3. However, when fly ash is blended, Since the amount of the powder further increases, kneading failure tends to occur. About this, the result of having investigated the relationship between the said strength index and the slump value of a mixed material on the conditions which mix | blended fly ash 25 mass% in the ratio with respect to the mass of blast furnace slag fine powder is shown in FIG. In this test, clay with a silt content of 92% by volume was used as mud, blast furnace slag fine powder was mainly used as a binder, slaked lime and ordinary Portland cement were used as alkali stimulants, and fly ash was further blended.

According to FIG. 3, when the strength index is up to 1.5, the slump value is 3 cm or more and an appropriate kneading state is obtained, but when the strength index exceeds 1.5, the slump value is greatly reduced. In addition, the tendency to start kneading failure was also confirmed visually. For this reason, if the strength index exceeds 1.5, the strength itself reaches the peak, but if the strength index further increases, the strength decreases. Therefore, when fly ash is blended as a part of the binder, the strength index is desirably 1.5 or less.

The amount of water in the mixed material is determined by the moisture content, volume ratio and strength index of the clay. Generally, the volume ratio in the mixed material is about 30 to 50%.
Aggregates can be blended into the mixed material in the same manner as concrete and the like, and it is desirable to blend aggregates in terms of characteristics such as volume stability. As the aggregate, natural sand and natural crushed stone can be used in the same manner as ordinary concrete. However, from the viewpoint of obtaining a high strength material containing as little natural resources as possible, it is desirable to use steel slag. Moreover, since steelmaking slag is heavier (larger specific gravity) than natural crushed stone, the weight (high specific gravity) of a solidified body can be ensured by using this as an aggregate.

Examples of the steelmaking slag include hot metal pretreatment slag (dephosphorization slag, desiliconization slag, desulfurization slag, etc.), converter decarburization slag, electric furnace slag, and the like, and one or more of these can be used. The steelmaking slag preferably has a maximum particle size of 25 mm or less.
About 15 to 50% of the aggregate is appropriate as the volume ratio in the mixed material. Moreover, when using steelmaking slag as an aggregate, it is preferable that the amount of steelmaking slag in a mixed material is 700 kg / m < ³ > or more from a viewpoint of the weight ensuring as a solidified body, and volume stability.

In the production method of the present invention, mud, a binder, and more preferably an aggregate are blended, a mixed material to which water is added as necessary is kneaded, and the kneaded material is solidified by a hydration reaction of the binder to produce artificial material. Get stone.
Remove mud such as dredged material with a sieve if necessary. As a means for kneading the mixed material, for example, a normal fresh concrete kneading facility may be used, but it may be carried out in a yard such as outdoors using a heavy machine for civil engineering work such as an excavator.
In order to solidify the kneaded material, for example, it may be poured into an appropriate mold and solidified and cured (hydration hardening), or it may be cast in a layer on the yard such as outdoors to solidify and cure (hydration hardening). You may let them. In particular, when a large amount of stone is produced, it is preferable to place the yard in layers.

The results of examining the relationship between the curing period and the strength of the solidified body (uniaxial compressive strength after 28 days of curing) are shown in FIG. In this test, clay with a silt content of 60% by volume was used as mud, blast furnace slag fine powder was mainly used as a binder, and slaked lime and ordinary Portland cement were used as alkali stimulants. The ratio of the amount of binder in the mixed material to water is (mass of blast furnace slag fine powder + mass of lime powder + mass of slaked lime + mass of ordinary Portland cement × 2) / (mass of water in the mixed material) ) <2.0. The curing period is a period until a target compressive strength is obtained. Generally, about 7 days or more is appropriate as shown in FIG.

The obtained stone is crushed to an appropriate size as necessary. This crushing treatment may be performed using a crusher, and when the kneaded material is placed in layers in the yard as described above, the solidified body of the yard is roughly crushed with a breaker, and then crushed. You may crush with a machine. Moreover, normally, the solidified body (lumps) subjected to the crushing process is classified with a sieve to obtain a chunk of a predetermined size. For example, when used as a submerged dike material, a lump having a size of about 150 to 500 mm is obtained.

The stone material has a uniaxial compressive strength after curing on the 28th of 9.8 N / mm ² (the hardness of semi-hard stone specified in JIS-A-5006: 1995) or more, preferably 15 N / mm ² or more. Although preferable, according to the manufacturing method of the present invention, a stone having such strength can be easily manufactured. In particular, solidified bodies manufactured using steelmaking slag as aggregate, especially solidified manufactured using steelmaking slag as aggregate and blast furnace slag fine powder and alkaline stimulant (eg ordinary Portland cement) as binder. The body can ensure sufficient strength and weight (high specific gravity).

Next, a method for manufacturing the artificial stone material using the dredged soil stored in the dredging yard once stored in the dredging yard is described below.

浚渫 The dredged soil generated by dredging works varies in moisture content depending on dredging location. In addition, when marine products (such as seaweed and oysters) are cultivated in the vicinity of dredging work, the dredging of seawater due to dredging work may affect the marine products. Rather, there is a limit on the construction period (ie seasonality). When carrying out the present invention in such a situation, the dredged soil generated by dredging work is temporarily stored in the dredging yard, and a solidified body is produced using the dredged soil stored in the dredging yard. Is preferred. This makes it possible to average the moisture content of the dredged soil by storing it in the dredging yard once (i) even if the moisture content of the dredged soil varies depending on the dredging location, etc. Even when the construction period is limited and there is a period when dredging can not be collected annually, it is possible to stably supply dredged soil to the solidified body manufacturing process by storing mud in the dredging yard. iii) By storing the dredged soil in the dredging yard, the water content ratio can be easily evaluated, managed and adjusted, and the like can be obtained.

FIG. 5 is an explanatory view showing an embodiment of the present invention using a dredging site. The dredged soil generated during dredging work is temporarily stored in the dredging yard. The form and structure of the dredging yard is arbitrary, for example, it may be a thing that piles earth and sand, slag, etc. in a yard to form an annular bank and stores dredged mud inside. The dredged soil generated during dredging work is transported to the dredging yard and stored, regardless of its water content and other properties. The above-mentioned binder, more preferably aggregate, is mixed into the clay supplied from this dredging site, and a mixed material to which water is added as necessary is kneaded. To obtain artificial stone.

[Example 1]
Table 2 and blended materials in compounding conditions shown in Table 3 (mixed for 5 minutes at 0.75 m ³ kneading plant, discharged after a predetermined time has elapsed) kneading, diameter 100 mm × a kneaded product of this mixed material A solid body (artificial stone material) was produced by molding into a mold having a height of 200 mm and solidifying. The dredged soil used was 90% by volume of silt collected from the bottom of Tokyo Bay. Water was adjusted as necessary by adding water. Moreover, converter slag (particle size 0-25 mm) was used as the steelmaking slag, which is an aggregate. The uniaxial compression strength of the solidified body after curing for 28 days was measured by a compression test (JIS-A-1108: 2006). The results are also shown in Table 2 and Table 3.

According to Table 2 and Table 3, in the example of the present invention, a solidified body (stone material) having a stable strength that sufficiently satisfies the characteristics of the quasi-hard stone even when the safety factor (+3 N / mm ² ) is taken into consideration. . On the other hand, in the comparative example, the strength is 9.8 N / mm ² or more, which is higher than that of Patent Document 3, but a solidified body having sufficient strength is obtained in consideration of the safety factor. Absent.

[Example 2]
By mixing the materials with the blending conditions shown in Table 4 (mixed for 5 minutes at 0.75 m ³ kneading plant, discharged after a predetermined time has elapsed) kneading, the kneaded product a diameter 100 mm × height 200mm of this mixed material A solid body (artificial stone) was manufactured by molding into a mold of the size. The dredged soil used was 92% by volume of silt collected from the bottom of the Seto Inland Sea, and water was adjusted as necessary by adding water. Moreover, converter slag (particle size 0-25 mm) was used as the steelmaking slag, which is an aggregate. The uniaxial compression strength of the solidified body after curing for 28 days was measured by a compression test (JIS-A-1108: 2006). The results are also shown in Table 4.

According to Table 4, in the example of the present invention, a solidified body (stone material) having a stable strength that sufficiently satisfies the characteristics of the semi-hard stone even when the safety factor (+3 N / mm ² ) is taken into consideration. On the other hand, in the comparative example, the strength is 9.8 N / mm ² or more, which is higher than that of Patent Document 3, but a solidified body having sufficient strength is obtained in consideration of the safety factor. Absent.

Claims

A method for producing an artificial stone material by hydrating and hardening a mixed material containing mud and a binder, wherein the mixed material satisfies the following conditions (a) to (c).
(A) Containing 40 vol% or more of mud with respect to 100 vol% of the mixed material.
(B) The binder comprises at least one selected from blast furnace slag fine powder, blast furnace slag fine powder to which an alkali stimulant is added, blast furnace cement, and ordinary Portland cement.
(C) The amount of the binder is 1.7 times or more by mass ratio with respect to the soil particles (solid content) in the mud and satisfies the following formula.
(Mass of blast furnace slag fine powder + Mass of lime powder + Mass of slaked lime + Mass of ordinary Portland cement × 2) / (Mass of water in mixed material) <2.0
2. The binder according to claim 1, wherein the binder contains 80 to 95% by mass of blast furnace slag fine powder, and the balance is at least one selected from ordinary Portland cement, lime powder, slaked lime, and blast furnace cement. Manufacturing method for artificial stone.
A method for producing an artificial stone material by hydrating and hardening a mixed material containing mud and a binder, wherein the mixed material satisfies the following conditions (d) to (f).
(D) Containing 40 volume% or more of mud with respect to 100 volume% of mixed materials.
(E) The binder comprises at least one selected from blast furnace slag fine powder, blast furnace slag fine powder to which an alkali stimulant is added, blast furnace cement, and ordinary Portland cement, and fly ash.
(F) The amount of the binder is 1.7 times or more by mass ratio with respect to the soil particles (solid content) in the mud and satisfies the following formula.
(Mass of blast furnace slag fine powder + Mass of lime powder + Mass of slaked lime + Mass of ordinary Portland cement × 2 + Mass of fly ash × 0.35) / (Mass of water in mixed material) ≦ 1.5
The binder contains 70 to 85% by mass of ground granulated blast furnace slag and 10 to 30% by mass of fly ash in proportion to the mass of ground granulated blast furnace slag, with the balance being ordinary Portland cement, lime powder, slaked lime, blast furnace The method for producing an artificial stone material according to claim 3, wherein the method is one or more selected from cement.
The method for producing an artificial stone material according to any one of claims 1 to 4, wherein the mixed material further contains an aggregate.
The method for producing an artificial stone according to claim 5, wherein the aggregate is steel slag.
The method for producing an artificial stone material according to claim 6, wherein the compounding amount of the steelmaking slag per unit volume in the mixed material is 700 kg / m 3 or more.
The method for producing an artificial stone material according to any one of claims 1 to 7, wherein the mud contains 65 vol% or more of particles having a particle size of 0.075 mm or less.
The mud is a dredged material generated by dredging work, and the dredged material is temporarily stored in a dredging yard, and artificial stone is produced using the dredged material stored in the dredging yard. Item 9. The method for producing an artificial stone material according to any one of Items 1 to 8.