WO2014167874A1 - Method for producing hydrated solidified body, and hydrated solidified body - Google Patents

Abstract

A method for producing a hydrated solidified body is a method for producing a hydrated solidified body by kneading a granular steel-making slag and a SiO₂-containing substance together with water. The method is characterized in that the steel-making slag to be used is one that can have a disintegration rate of 2.5 mass% or less after being immersed in warm water having a temperature of 80˚C for 10 days and has a coarse granule ratio of 4.5 or more, and the SiO₂-containing substance to be used is a blast furnace slag fine powder or a mixture of a blast furnace slag fine powder and fly ash.

Description

Method for producing hydrated solid body and hydrated solid body

The present invention relates to a method for producing a hydrated solid product produced by kneading a granular steelmaking slag and a SiO ₂ -containing substance with water, and to a hydrated solid product.

Slag generated in the steelmaking process (hereinafter abbreviated as steelmaking slag) has a high basicity and contains a large amount of free CaO. For this reason, since steelmaking slag is easy to expand | swell by a hydration reaction, it is not suitable for the use as a civil engineering / construction material like a blast furnace slag, and is difficult to process. Therefore, in recent years, a technique for actively utilizing steelmaking slag has been proposed in order to overcome such a situation. Specifically, Patent Document 1 contains 50% or more of one or two of an aggregate containing steelmaking slag, a silica-containing material having latent hydraulic properties, and a silica-containing material having pozzolanic reactivity. A method for producing a hydrated solid body by mixing a binder that solidifies by a hydration reaction is described. Patent Document 2 discloses a steel slag obtained by pulverizing and crushing all of a binder, fine aggregate, and coarse aggregate, and using a steel slag mixed with blast furnace slag and steelmaking slag as a binder. Slag blocks (hydrated solids) are described.

Japanese Patent Laid-Open No. 10-152364 JP-A-2-233539 Japanese Patent No. 3654122 Japanese Patent No. 4438307

However, when the inventors of the present invention prototyped a hydrated solid body made of steel slag as a raw material using the production methods described in Patent Documents 1 and 2, the following problems were revealed.

That is, according to the manufacturing method described in Patent Document 1, when converter slag is used as steelmaking slag, the hydrated solidified body may not be satisfactory when cured in water at 20 ° C. . Therefore, as a result of detailed investigation of the cause by the inventors of the present invention, when the CaO content and the MgO content added in the steelmaking process are not completely dissolved in the slag, or are precipitated during cooling. In addition, it was found that the hydrated solidified body collapsed. This is because the CaO content and MgO content present in the form of CaO and MgO in the slag are hydrated and expanded by underwater curing. On the other hand, when the steelmaking slag including the binder is mainly used as in the manufacturing method described in Patent Document 2, in most cases, the compressive strength of the hydrated solidified body is insufficient and stable. It was difficult to develop the strength. Therefore, the hydrated solid body produced by the production method described in Patent Document 2 cannot withstand use as a substitute for cement and concrete.

In order to solve such problems, a method for producing a hydrated solid body using a material mainly composed of blast furnace slag fine powder as a binding material has been proposed and put into practical use, while limiting the types of steelmaking slag. ing. In this production method, hot metal pretreatment slag is used as the steelmaking slag, and the ratio of particles having a particle size of 1.18 mm or less is within the range of 15 to 55% by mass of the total amount excluding water. 3. Patent Document 4 describes a technique for producing a stable hydrated solid body by limiting the powdering rate of steelmaking slag.

Therefore, the inventors of the present invention have confirmed that good properties can be obtained with respect to strength and volume stability as a result of producing a hydrated solid body based on these findings. As a result of the follow-up investigation by exposing the hydrated solid body thus obtained to various environments, it was found that there was no particular problem when it was immersed in the sea or river. However, it has been found that there are rare cases where large-scale cracks and breakage occur after several years when exposed to rain and sunshine on the coastal tidal zone and on land. About this, in the range which removed the core etc. from the residual part and evaluated the static compressive strength, the big strength fall was not recognized but the cause which a crack etc. generate | occur | produced was not clear.

In order to use industrial by-products represented by steelmaking slag more effectively, hydrated solidified products are not limited to being used in the sea or underwater, but can be used as a substitute for wave-dissipating blocks in coastal areas and soil concrete in land areas. It is indispensable to use it for various purposes. In that case, since the hydrated solidified body is used over a long period of time in various natural environments such as air temperature and sunshine, long-term durability is also a necessary characteristic. Conventionally, many studies have been made on the durability resulting from the expansion stability of steelmaking slag. However, even when using steel slag with a stable volume based on past knowledge, there is no problem with small sizes, but durability may be inferior when large products are exposed under certain conditions. I found out that there was a need for countermeasures.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a hydrated solid body capable of obtaining a hydrated solid body having high durability even in an environment where repeated stress is applied. There is to do. Another object of the present invention is to provide a hydrated solid body having high durability even in an environment where repeated stress is applied.

It is said that a powdered steelmaking slag having a low pulverization rate has a function similar to that of aggregate in concrete and partly contributes to the reaction of the binder. There is no special provision for the particle size of steel slag other than 25 mm or less (see “Steel Slag Hydrated Solid Technology Manual” (Coastal Technology Research Center)). Further, as described above, Patent Document 3 describes that the ratio of particles of 1.18 mm or less is within the range of 15 to 55% by mass of the total blending amount excluding water.

The inventors of the present invention kneaded steelmaking slag satisfying this condition under various blending conditions, and as a result of evaluating the exposure of the hydrated solidified product, it was found that there was no problem with rubble or small blocks. It was. However, cracks will occur if the block is a large block that weighs more than 2.5 tons as a lump, or if it is placed in an environment where the heat environment and dryness and humidity change cyclically. I found out that there was a case.

And the inventors of the present invention have found that the influence of the grain size of the steelmaking slag is extremely large as a result of intensive investigation of the cause. The inventors of the present invention not only determine the proportion of particles having a fine particle size of 1.18 mm or less, but also find that it is important that particles having a large particle size are present in an appropriate proportion. I came up with the idea.

The method for producing a hydrated solid body according to the present invention is a method for producing a hydrated solid body produced by kneading a granular steelmaking slag and a SiO ₂ -containing substance with water, and as the steelmaking slag, A steelmaking slag having a powdering rate of 2.5% by mass or less after being immersed in warm water of 80 ° C. for 10 days and a coarse rate of 4.5 or more is used, and the blast furnace slag is used as the SiO ₂ -containing material. Fine powder or blast furnace slag fine powder and fly ash are used.

In the above invention, the method for producing a hydrated solid body according to the present invention uses, as the steelmaking slag, a steelmaking slag having a particle size within a range of 0.5 mm or less in a ratio of 10% by mass or more. It is characterized by.

The method for producing a hydrated solid product according to the present invention is the above-mentioned invention, wherein one or two selected from alkali metal and / or alkaline earth metal oxides, hydroxides, sulfates, and chlorides are used. The seed or more is added within a range of 0.2 to 20% by mass with respect to the total content of blast furnace slag fine powder and fly ash.

The method for producing a hydrated solid body according to the present invention is the above-described invention, wherein one or more selected from ordinary Portland cement, fly ash cement, and composite cement are contained in total of fine blast furnace slag powder and fly ash. 200 mass% is added as an upper limit with respect to the quantity, It is characterized by the above-mentioned.

The method for producing a hydrated solid product according to the present invention is the above invention, wherein naphthalene sulfonic acid and / or polycarboxylic acid is mixed with blast furnace slag fine powder, fly ash, and an oxide of alkali metal and / or alkaline earth metal, It is characterized by being added within a range of 0.1 to 2.0% by mass with respect to the total content of hydroxide, sulfate and chloride.

The hydrated and solidified product according to the present invention is characterized by being manufactured using the method for producing a hydrated and solidified product according to the present invention.

The hydrated solidified material according to the present invention is characterized in that, in the above-mentioned invention, the 1 million times fatigue strength after solidification exceeds 50% of the static fatigue strength.

In the above invention, the hydrated and solidified product according to the present invention is characterized by being used in a tidal zone, a splash zone, or a land area on the coast of the sea area.

In the above invention, the hydrated solid body according to the present invention is used for a member having a weight of 1 ton or more.

According to the present invention, it is possible to provide a hydrated solid body having high durability even in an environment where repeated stress is applied.

FIG. 1 is a diagram illustrating an example of the relationship between the FM value of steelmaking slag and the number of repeated loads until failure. FIG. 2 is a diagram showing an example of the relationship between the slag diameter on the fine grain side 10% and the slump of the kneaded product.

A hydrated solid body produced using steelmaking slag is produced by using a steelmaking slag having low expansion stability as an aggregate equivalent material, and further adding a binder and water and kneading. In the present invention, in order to obtain high durability, steelmaking slag that satisfies the following conditions (1) and (2) including the above is used. Further, in the present invention, as a binder, using a blast furnace slag or blast furnace slag and SiO ₂ containing material such as fly ash.

(1) Low content of expansive minerals such as CaO and MgO and low powdering rate (2) Coarse grain ratio (FM value) of 4.5 or more

Examples of the steelmaking slag include hot metal pretreatment slag (such as dephosphorization slag and desiliconization slag), 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.

In the steelmaking slag, CaO and MgO are mixed in the refining process. Many parts of CaO and MgO form complex oxides with other elements such as SiO ₂ and FeO, but some exist in the state of free CaO and free MgO. If a large amount of free CaO or free MgO remains as it is, it reacts with moisture to become Ca (OH) ₂ or Mg (OH) ₂ and expands. These mineral phases can be kept low by controlling the composition and cooling of the steelmaking slag.

By freezing steelmaking slag in the outdoor yard for a long time or by steam aging to promote the hydration reaction, free CaO and free MgO are converted into Ca (OH) before being used for the production of hydrated solidified bodies. ₂ or Mg (OH) ₂ . Thereby, there is no problem when using the steelmaking slag as an aggregate equivalent material. About this, if the steelmaking slag to be used has a ratio of 2.5% by mass or less when it is heated to 80 ° C. for 10 days with hot water curing, the strength of the hydrated solid body is not affected. Therefore, even if such a steelmaking slag is used in small product applications that are less susceptible to environmental changes such as stress, there is no effect on product damage or the like.

Based on conventional knowledge, only a ratio of particles with a particle size of 1.18 mm or less was specified for steelmaking slag, and a large block was manufactured and exposed to land and tidal zones. Was observed to occur. Applications using large shapes need to be large, in other words, it is not desirable that the weight of a single unit be reduced due to breakage during use. Therefore, high durability is required compared to uses such as stone substitutes.

As a result of intensive investigations on the conditions that do not cause breakage based on the raw material composition and material characteristics of such a large shape that has broken, not only the fine particle size ratio of the steelmaking slag to be used, but also the balance of the overall particle size It was found that the durability greatly changes depending on the condition. Steelmaking slag is different from natural stone, and uses a product obtained by solidifying and crushing the melt as a by-product.Therefore, the particle size varies depending on the subsequent use. Was found to be important.

Therefore, it was investigated how many times the load was applied when a repeated load having a strength equivalent to 50% when the static fracture strength of each condition was 100% was applied. As a result, it was found that when the characteristics of the aggregate were evaluated by FM (Fitness Modulus) value, which is an index of particle size, the relationship became clear. That is, the particle size distribution is measured by sieving with sieves having a sieve opening of 37.5, 19.0, 9.50, 4.75, 2.36, 1.18, 0.60, 0.30, and 0.15 mm. Then, the total number of masses remaining on the sieve was summed and divided by 100, and the number of fractures was examined as an FM value. As a result, as shown in FIG. 1, when the FM value becomes small, the breakage easily occurs. When the FM value is 4.5 or more, the fatigue durability exceeding 1 million times, and the FM value is 4.8 or more. Thus, it was found that fatigue durability of 2 million times or more can be secured. That is, the inventors of the present invention have found that when the FM value of steelmaking slag is 4.5 or more, more desirably 4.8 or more, a highly durable hydrated solid body can be obtained.

In addition, in this specification, a large-sized member means a member having a weight exceeding 1 ton by itself. For a member having a weight of less than 1 ton, stable performance can be roughly obtained even if the FM value is less than 4.5. However, when a part of the structure is structurally loaded or when the wet and dry fluctuation is large, it is desirable to use a member having an FM value of 4.5 or more even for a member having a weight less than 1 ton.

On the other hand, even if the FM value is increased, from the viewpoint of fluidity, the range is naturally limited depending on the construction method and the like, and the FM value should be 6.4 or less, more preferably 6.0 or less. Is preferred. For example, when only steelmaking slag of about 5 mm is used, the fluidity of the kneaded material is lowered and the workability is deteriorated. For this reason, the inventors of the present invention further examined the conditions necessary for maintaining workability. As a result, the inventors of the present invention have found that the proportion of fine portions of steelmaking slag has a strong influence on kneading and construction.

Therefore, by paying attention to the diameter of the fine particle side 10 weight percent of the slag of steel slag _{(D 10),} the kneaded product in the same formulation (water 198 kg / ^{m 3,} the binder 527kg / ^{m 3,} steelmaking the remainder slag) The slump was investigated. As a result, as shown in FIG. 2, if the D ₁₀ of was below 0.5mm, in other words, if the ratio of particles less than 0.5mm was more than 10 mass%, good workability is maintained It was done. On the contrary, if the D ₁₀ of exceeds 0.5mm is, 0 cm in order to top of the specimen at the time of disconnect the slump cone had collapsed sideways without sinking, as an evaluation of the slump It was.

In the present invention in which the FM value is increased over the entire particle size, that is, the durability is ensured by increasing coarse particles, a steelmaking slag having an appropriate particle size distribution that has a ratio of particles of 0.5 mm or less is 10% by mass or more is used. This makes it possible to ensure high durability and good kneading / constructing properties.

By using the slag, a solidified body having high durability can be obtained by using steelmaking slag as an aggregate. Because of its high durability, it can be used not only for small applications but also for large members whose weight exceeds 1 ton. Especially for coastal tidal and splash zones where wetness and dryness are repeated, on land where rainfall and sunshine are repeated, etc., as a substitute for natural stones, as well as for concrete blocks such as wave-dissipating blocks It is possible to use.

The present invention ensures long-term durability by using the steelmaking slag as described above. In addition, 0.2% by mass or more of one or more selected from alkali metal and / or alkaline earth metal oxides, hydroxides, sulfates, and chlorides may be added. Good. Thereby, the initial strength of the hydrated solid body can be expressed stably, the solidification can be promoted, and the time required for curing can be shortened. Although the upper limit of the addition amount is not particularly limited, the effect is saturated even if added over 20% by mass, so the upper limit of the addition amount is 20% by mass.

Ordinary Portland cement, fly ash cement, and composite cement can also be used as auxiliary materials for SiO ₂ -containing materials. For example, when it is not economically advantageous to obtain a large amount of blast furnace slag fine powder, such as where the production site of the blast furnace slag fine powder is separated from the production site of the solidified body, or oxidation of alkali metal and / or alkaline earth metal Suitable for products, hydroxides, sulfates, and chlorides that are difficult to obtain. In this case, since the particle size composition of the fine powder portion changes and steelmaking slag having a high specific gravity is easily separated, the upper limit of these contents is 200% by mass with respect to the total content of the blast furnace slag fine powder and fly ash.

Addition of naphthalenesulfonic acid and / or polycarboxylic acid improves kneadability when the raw material is kneaded with water. Therefore, the amount of water required for kneading can be reduced, and as a result, a higher strength hydrated solidified product can be obtained. Effective if the addition amount is less than 0.1% by mass with respect to the total content of blast furnace slag fine powder, fly ash and alkali metal and / or alkaline earth metal oxides, hydroxides, sulfates and chlorides poor. On the other hand, even if added over 2.0 mass%, the effect is saturated, so the addition amount is limited to the range of 0.1 to 2.0 mass%.

〔Example〕
In the present Example, the hydrated solid body was produced using the granular steelmaking slag which adjusted the particle size. As the granular steelmaking slag, the hot metal pretreatment slag generated when the blast furnace hot iron discharged from the blast furnace was dephosphorized was used. In addition, blast furnace granulated slag fine powder and fly ash were used as the binder, and ordinary Portland cement was used as the alkali stimulating material. The particle size of the steel slag used in the test, FM value, and D ₁₀ represent respectively the particle diameters was selected as the condition of the range of the present invention and comparative. At that time the particle size, FM value, and _{D 10} shown in Table 1.

Powdered steelmaking slag, a binder, an alkali stimulant, and water were kneaded using a mixer with the formulation shown in Table 2. In order to evaluate workability, the slump of the kneaded product was measured by the slump test method of Japanese Industrial Standard JIS A 1101, and then molded into a 10 cm × 10 cm × 40 cm mold. The molded product was deframed after 2 days and cured in water at 20 ° C. for 28 days, and then subjected to a bending fatigue test. The bending fatigue test was repeatedly loaded at a frequency of 7 Hz with the 50% stress as the upper limit stress and the 5% stress as the lower limit stress based on the fracture stress obtained by the bending strength test method of Japanese Industrial Standard JIS A 1106. According to the number of times until destruction occurred, a case where the number of times exceeded 1 × 10 ⁶ times was judged as “◯”, and a case where the number of times was less than 1 × 10 ⁶ times was judged as “x”. The slump and durability results are also shown in Table 1.

As shown in Table 1, high durability was obtained when the coarse grain ratio of the steelmaking slag was within the range of the present invention. On the other hand, it was confirmed that durability was not able to be secured enough about the thing with a low coarse grain rate of steelmaking slag. Further, under the condition D ₁₀ of greater, although the durability can be secured, collapse around without the upper part of the specimen pulled slump cone fresh state sinks, could not be measured slump. D ₁₀ is depending largely be shaped and molding method can be molded, in order to workability and finish with a good solidified product, it is desirable to a D ₁₀ in the range of 0.5 or less Was confirmed. As described above, by making it within the scope of the present invention, it has become possible to stably exhibit high durability that has not been achieved in the past.

As described above, the present invention can be applied to the steel slag powder particulate and SiO ₂ containing material to a process of producing a hydrated solid material by kneading with water.

Claims (9)

1. A method for producing a hydrated solid body produced by kneading a granular steel-making slag and a SiO ₂ -containing substance with water,
   As the steelmaking slag, a steelmaking slag having a pulverization rate of 2.5% by mass or less after being immersed in hot water at 80 ° C. for 10 days and a coarse particle rate of 4.5 or more is used, and contains the SiO ₂ Blast furnace slag fine powder or blast furnace slag fine powder and fly ash are used as a substance, The manufacturing method of the hydrated solid body characterized by the above-mentioned.
2. 2. The method for producing a hydrated solid body according to claim 1, wherein the steelmaking slag is a steelmaking slag having a particle size within a range of 0.5 mm or less of 10% by mass or more. .
3. One or more selected from oxides, hydroxides, sulfates, and chlorides of alkali metals and / or alkaline earth metals with respect to the total content of blast furnace slag fine powder and fly ash The method for producing a hydrated solid body according to claim 1 or 2, wherein the addition is performed within a range of 0.2 to 20% by mass.
4. One or more kinds selected from ordinary Portland cement, fly ash cement, and composite cement are added up to 200 mass% with respect to the total content of blast furnace slag fine powder and fly ash. The manufacturing method of the hydrated solid body of any one of Claims 1 thru | or 3.
5. Naphthalene sulfonic acid and / or polycarboxylic acid with respect to the total content of blast furnace slag fine powder, fly ash, and alkali metal and / or alkaline earth metal oxides, hydroxides, sulfates, and chlorides It adds within the range of 0.1 to 2.0 mass%, The manufacturing method of the hydrated solid body of any one of Claims 1 thru | or 4 characterized by the above-mentioned.
6. A hydrated and solidified product produced using the method for producing a hydrated and solidified product according to any one of claims 1 to 5.
7. The hydrated solidified body according to claim 6, wherein the fatigue strength of 1 million times exceeds 50% of the static fatigue strength.
8. The hydrated solidified body according to claim 6 or 7, wherein the hydrated solidified body is used in a tidal zone, a splash zone, or a land area along the coast of the sea area.
9. The hydrated solid body according to any one of claims 6 to 8, which is used for a member having a weight of 1 ton or more.

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