JP4372810B2 - Construction material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a construction material and a method for producing the same, and more particularly to a construction material that can be used to regenerate mud soil having a high water content generated in civil engineering as soil, and a method for producing the same.

  In order to move the high moisture content mud generated in civil engineering work quickly and easily from the site, it is necessary to absorb the mud's moisture and regenerate it as soil. As means for absorbing the mud's moisture, a method is known in which (1) incineration ash, (2) cement, or (3) a polymer absorbent is added and mixed at the construction site.

  However, although the method (1) of adding and mixing incineration ash is excellent in water absorption, there is a problem that fine particles are not easy to handle and dust is generated. In addition, the method of adding and mixing the cement of (2) is excellent in solidification strength, but not only does it take time to solidify, but also requires crushing when reusing the mud after treatment, and the elution pH. However, there is a problem that vegetation has an adverse effect and is not suitable for reuse. Although the method (3) of adding and mixing the polymer absorbent is excellent in water absorption, the treated soil obtained contains a gel-like polymer absorbent. There is a problem that the yield strength is low.

  Furthermore, since the incineration ash of (1) contains harmful substances such as boron and fluorine regulated by the Ministry of the Environment Notification No. 18 of 2003, when using the incineration ash, this treatment can be done by applying some kind of treatment. You must meet the regulations.

  Then, the method of adding limestone etc. to a combustion furnace is proposed as a measure which insolubilizes the harmful substance contained in incineration ash, and / or makes it slightly soluble (for example, patent document 1).

As another method, a method of mixing incineration ash with a calcium compound, cement, and aluminum sulfate in the presence of water and adjusting the amount of fluorine and boron eluted to a soil environment standard or less has been proposed (for example, Patent Document 2).
JP 2005-134098 A JP 2006-181535 A

  However, in the method described in Patent Document 1, due to solidification and aggregation of limestone, sufficient water absorption cannot be ensured, and since the particle size of limestone is fine, dust is generated during handling and use as incinerated ash. There was a problem. Moreover, since it does not pay attention to removal of harmful substances derived from soil when mixed with soil, it is considered difficult to exhibit sufficient ability to remove harmful substances when mixed with soil.

  In the method described in Patent Document 2, the amount of fluorine and boron eluted from the treated incineration ash itself can satisfy the soil environment standard, but the amount of fluorine eluted from the mud itself is below the soil environment standard. It has been found that when mixed and used as a soil conditioner, a phenomenon that the amount of fluorine elution from the mixed mud increases significantly may occur. The reason for this is not clear, but at least cement can be mixed with incinerated ash in the presence of water to suppress the elution of fluorine because it is generally due to the incorporation of fluorine into the ettringite crystal structure. However, it is considered that this crystal structure is relatively easily broken by carbon dioxide or the like to liberate fluorine.

  On the other hand, although the soil of general environment contains fluorine at a concentration of 90 to 600 ppm, the elution amount is less than about 0.8 ppm relative to the fluorine content because fluorine is ionic with aluminum in the soil. It is presumed that they are coordinated to the soil, but the construction materials made from incineration ash treated with alkaline treatment agents such as cement, calcium, magnesium, and paper sludge incineration ash containing a large amount of calcium are used as mud. When mixed, it is presumed that hydroxide ions derived from alkaline substances coordinate with aluminum and thus liberate fluorine.

  As described above, a stable construction material and a method for producing the same, in which the fluorine elution amount is suppressed even by mixing with mud, have not been proposed.

  The present invention has been made in view of the above-mentioned problems, and is a construction material mainly composed of incinerated ash capable of absorbing moisture from mud with a high water content. It is an object of the present invention to provide a construction material that is suppressed in elution and has excellent ground strength, and a method for producing the same.

The construction material of the present invention used to solve the above-mentioned problems is a construction material obtained by blending an incinerated ash granulated material mainly composed of incinerated ash, aluminum sulfate and cement with an alkaline earth metal compound. The incinerated ash granulated product is obtained by mixing the incinerated ash with the aluminum sulfate and the cement in the presence of at least water to obtain a granulated product (a), and drying the granulated product. In accordance with the aggregate sieving test specified in JISA1102, it passes through a sieve with a nominal opening of 8 mm specified in JISZ8801-1 and passes through a sieve with a nominal opening of 106 μm. The mass ratio of the formulation which does not pass is 60 mass% or more of the whole. The moisture content of the incinerated ash granulated product is preferably 3% by mass or less. More preferably, it is 0.5-3.0 mass%, More preferably, it is 1.0-2.5 mass%, Preferably, the said alkaline earth metal compound is calcium oxide, calcium hydroxide, magnesium oxide, hydroxylation. Magnesium, or a combination thereof. The amount of the alkaline earth metal compound is preferably 3 to 25 parts by mass with respect to 100 parts by mass of the dry mass of the incinerated ash granulated product.

  Furthermore, when the construction material is mixed with mud to make treated soil, the amount of fluorine eluted by the dissolution test method based on the Ministry of the Environment Notification No. 18 of 2003 is 0.8 mg / L or less. It is preferable.

  Further, the present invention is a method for producing a construction material comprising a mixture of incinerated ash granulated material mainly composed of incinerated ash, aluminum sulfate and cement, and an alkaline earth metal compound, wherein the incinerated ash is At least in the presence of water, the aluminum sulfate and the cement are mixed to obtain a granulated product (a), and the granulated product is dried (b), and then the incinerated ash granulated product. And the step of mixing the incinerated ash granulated product and the alkaline earth metal compound in this order.

  When mud is treated with the construction material of the present invention, it is possible to suppress elution of fluorine from the treated soil obtained after mixing. Further, according to the production method of the present invention, it is possible to provide a construction material capable of suppressing elution of fluorine even when mixed with mud.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The construction material according to the present invention is a mixture of dried incineration ash and aluminum sulfate, cement, and water for making toxic substances in the incineration ash non-eluting, granulated, and dried the granulated product. An incinerated ash granulated product and an alkaline earth metal compound are blended. FIG. 1 is a flowchart showing a construction material manufacturing method according to this embodiment. In this embodiment, as shown in FIG. 1, incineration ash is used as a main raw material, aluminum sulfate and cement are mixed in the presence of water (st1), and the mixed raw material is granulated (st2). With or without curing, the granulated product is dried (st3) to prepare an incinerated ash granulated product. Then, an alkaline earth metal compound is added to the incinerated ash granulated product after drying (st4) to produce a construction material. The granulation step (st2) reduces the amount of fluorine elution after mixing with mud, and facilitates the prevention and handling of dust from construction materials. The incineration ash used as a raw material in the present invention is combustion ash generated when burning coal, RPF (fuel consisting of paper, waste materials, waste plastics, etc.), waste tires, wood chips, building waste materials or papermaking sludge. is there. In the present embodiment, incineration ash (paper sludge incineration ash) generated when papermaking sludge is burned is preferably used.

  This paper sludge incineration ash is made of paper such as ash that is captured by the dust collector when sludge produced by wastewater treatment from the paper mill is incinerated, and ash that is discharged from the lower part of the incinerator without being scattered from the incinerator. This refers to incineration ash that has been discharged from the factory and generally disposed of after being incinerated, and usually contains traces of harmful substances regulated by the Ministry of the Environment Notification No. 18 such as fluorine and boron. It is out.

  In order to insolubilize the above-mentioned harmful substances, it is preferable to mix aluminum sulfate, cement, and water with the raw material used in the mixing treatment of st1. In addition to the above, sulfate, phosphate, aluminum compounds, and other materials that have toxic substance aggregating ability and toxic substance adsorbing ability are adjusted individually or in combination depending on the type, content, etc. of toxic substances, and their addition The amount may be adjusted appropriately for use.

  Moreover, in st1, it is preferable to contain the solidifying agent for adjusting the intensity | strength of the construction material obtained in a raw material. As the solidifying agent, a calcium compound such as cement, gypsum, lime, etc., such as a material that exhibits solidification ability and coagulation ability by hydration reaction or the like, is adjusted alone or in combination, and the amount of addition is also adjusted appropriately. Cement is preferably used from the viewpoint of the granulating property described later, as well as the insolubilizing effect of harmful substances. Cement also has the advantage of being inexpensive. As the cement, blast furnace cement obtained by uniformly mixing blast furnace slag with Portland cement can be suitably used.

  The mixing treatment of st1 is performed in the presence of water. The water addition rate is based on the insolubility reaction of fluorine and the appropriate solidification reaction of construction materials, mixing properties, granulation properties as described below, and dryness (shortening drying time, energy suppression), in terms of total moisture content. It is preferable to adjust the content to be 20 to 40% by mass. In addition, when the raw material and other additive materials contain water in advance, the total moisture content including the contained water is 20 to 40% by mass, and more preferably, the granulating property and the It is preferable to adjust so that it may become 25-35 mass% from the porous surface of a granule, especially 28-32 mass%. Various known mixers can be used for mixing incineration ash, aluminum sulfate, cement, water and the like.

  In this embodiment, a granulated product is obtained by performing the granulation process of st2 after mixing the incinerated ash, aluminum sulfate, cement, water and the like.

  As a granulation method of the mixture, a granulator of a known method such as a reverse flow method, a rolling method, a stirring method, an extrusion method, or a crushing method can be appropriately used. Preferably, from the point of having both functions of mixing and granulation, performing mixing and granulation efficiently, and easily adjusting the porosity of the granulated product and the softness of the lump. A reverse flow mixer is preferably used.

  When granulation is performed in a reverse flow manner, the particle diameter can be adjusted by the granulation time. When the granulation time is short, granulation does not proceed and the particle size is reduced, and when the granulation time is long, granulation proceeds and the particle size is increased. However, the particle size does not grow beyond a certain size. This is presumably because the larger the particle diameter, the more the force applied to the particles during granulation concentrates on a part of the whole particles, so that the particles are easily broken. The granulation time is preferably 1 to 30 minutes, more preferably 3 minutes to 20 minutes, and even more preferably 5 minutes to 15 minutes.

  The granulation treatment can be performed after drying of st3, but is preferably performed before drying. After the granulation, when an alkaline earth metal compound is added through a drying process, it passes through a sieve with a nominal opening of 8 mm specified in JISZ8801-1 according to the aggregate screening test specified in JIS A1102, The mass ratio of the composition that does not pass through the 106 μm sieve is 60% by mass or more of the total. Therefore, the particle diameter of the granulated product (hereinafter, when the particle diameter varies depending on the measurement position in the particle, the “particle diameter” means “particle long diameter”) is 106 μm or more and 8 mm or less. It is preferable to adjust the granulation time to be 80% by mass or more. This is because in the subsequent drying step, particles are destroyed during drying and the particle size is reduced, and since the alkaline earth metal compound has a particle size of about 0.1 mm, an alkaline earth metal compound was added. This is because the construction material obtained later has a particle diameter that is lower than that of the granulated product.

  There are the following two reasons for adjusting the particle diameter after granulation. First, by adjusting the specific surface area of the granulated product within a predetermined range by granulation, the carbon incorporated in the ettringite crystal structure is prevented from being destroyed by carbon dioxide. It is for adjusting the specific surface area which touches.

  The second reason is to allow a later-described alkaline earth metal compound to adhere appropriately to the surface of the granulated product. That is, when the granulated product having a particle diameter of less than 106 μm increases, the surface area per unit mass increases and the alkaline earth metal compound can adhere only to a part of the granulated product surface. Moreover, when the granulated product having a particle diameter exceeding 8 mm increases, the alkaline earth metal compound may be excessive with respect to the surface area of the granulated product in a large granulated product, and the fluorine is not eluted. Therefore, it becomes difficult for the alkaline earth metal compound of the amount necessary to adhere to the surface of each granule evenly. Any of them is not preferable because it is difficult to prevent elution of fluorine from the treated soil in which the construction material and the mud are mixed.

  From the above, it is preferable to adjust 80% by mass or more of the incinerated ash granulated product before adding the alkaline earth metal compound to a particle size of 106 μm or more and 8 mm or less. About 60 mass% or more of the whole construction material after the addition can be adjusted to a particle diameter of 106 μm or more and 8 mm or less. By setting the particle diameter of the construction material within this range, elution of fluorine from the treated soil after mixing the construction material and mud can be effectively suppressed.

  In this embodiment, in order to further improve fluorine non-elution and to suppress the generation of dust and improve handling, the granulated product may be sieved before drying. As a sieving method, a known system such as a vibration type or a rotary type can be used.

  The average particle diameter before drying of the granulated product obtained by the granulation is preferably 0.1 to 8 mm, more preferably 0.2 to 2 mm from the viewpoint of drying. If it is less than 0.1 mm, the drying property is good, but it is easy to make fine particles, so that fluorine is easily eluted. On the other hand, dust is generated during use. If it exceeds 8 mm, it may be difficult to perform a uniform drying treatment.

  The granulated product having a particle diameter of less than 0.1 mm obtained by sieving the above-mentioned granulated product may be added to the raw material before the granulation treatment. Such a granulated product has an effect of facilitating the generation of the granulated product as a seed mass of granulation in the granulation process, and can improve the production efficiency. A granulated product having a particle size of 8 mm or more obtained by sieving the above-mentioned granulated product may be granulated with a desired particle size by crushing with a crusher. As the crusher, those of various known types can be used, but in the case of a soft material having a total water content of 20 to 40% by mass as in this embodiment, a crusher of the vertical axis type is used. It is preferable to use it because it is difficult to improve production efficiency and generate unnecessary fine granulated products. In addition, although the process of crushing and sieving may be performed after curing as described later, it is preferable to perform after granulation and before curing in order to obtain stable quality efficiently. In order to promote the reaction of the incinerated ash, sulfuric acid band, cement, and water blended in the above granulated product, it is preferable to provide a curing period after granulation. The curing time is preferably 4 hours or longer and less than 7 days, more preferably 12 hours to 2 days, and most preferably 18 hours to 36 hours. In curing for 7 days or more, the granulated material may solidify. In less than 4 hours, the harmful substances may not be sufficiently fixed and elution may occur, and the moisture distribution of the granulated material is stabilized. In many cases, there is a problem that the lump of the granulated product is broken during drying in the next step.

  After granulation, curing is preferably performed, followed by drying treatment of st3. As a drying method, a known method such as a kiln method, a conveyor belt conveyance method, or a fluidized bed method can be adopted. In the fluidized bed method, either a vertical type or a horizontal type can be used. Among these, a method in which the granulated product is not miniaturized by a mechanical external force during drying and thermal efficiency is preferable. Here, the kiln type is a drying method in which the granulated material is continuously charged from one end of the rotating drum, the inside of the drum is directly heated by a burner, and the dried granulated material is continuously taken out from the other end of the drum. Say. Moreover, a conveyor belt conveyance type means the system which conveys granulated material with a conveyor belt toward the other end from the heated dome, and performs drying. Furthermore, the fluidized bed type means that the granulated material is continuously charged into a fluidized bed having a large number of hot air blowing holes on the bottom surface, and the granulated material is moved upward or side as the drying proceeds with the hot air blown from the bottom surface of the fluidized bed. This is a system in which the dried granulated product is continuously taken out from the take-out port. In the fluidized bed system, there are a vertical type and a horizontal type as described above, but in the case of the present invention, a horizontal type that is less susceptible to breakage due to dropping is preferable, and an agitation delivery mechanism that applies an external force to an object to be dried inside the drying apparatus. A method that does not have the above is more preferable. In addition, weirs are provided inside to divide the fluidized bed into a plurality of sections, and the granulated material thrown into the upstream section moves upward as the drying proceeds with hot air blown from the bottom, and further downstream Those designed to move to the compartment are more preferable from the viewpoint of drying efficiency.

  FIG. 2 is a diagram showing a specific configuration of a horizontal fluidized bed drying apparatus provided with the above-mentioned weirs. The horizontal fluidized bed drying apparatus 12 includes a ventilation plate 1 and a plurality of 2 that divides the ventilation plate 1 into a plurality of sections, and a granulated product 10 is supplied from a conveyor 7 on the upstream side of the ventilation plate 1. The Below the ventilation plate 1, a fan 3 for taking in outside air and a heater 4 for heating the air from the fan 3 with steam are provided. The hot air supplied from the heater 4 passes through the ventilation plate 1 and comes into contact with the granulated product 10, whereby the granulated product 10 is dried. The air after coming into contact with the granulated material 10 is discharged to the outside through the fan 5 and the silencer 6. The granulated product 10 heated on the ventilation plate 1 loses moisture and becomes gradually lighter, and moves over the weir 2 to the next section. In the next section, the granulated material 10 is further heated and finally discharged onto the conveyor 8 on the downstream side. The moisture content of the dried granulated product is preferably 3.0% by mass or less so that the cement solidification reaction does not proceed excessively.

  Further, in order to effectively attach the alkaline earth metal compound added in the post-process to the granulated product, the water content after drying the granulated product is 3.0 mass% or less, preferably 0.8%. It is 5-3.0 mass%, More preferably, you may be 1.0-2.5 mass%. At these moisture contents, since the alkaline earth metal compound effectively adheres to the surface of the granulated product, the effect of non-eluting free fluorine is high. In other words, when the construction material is mixed with mud, hydroxide ions of alkaline substances derived from the construction material are generated, coordinated to aluminum, and even if fluorine in the mud is liberated, hydroxide ions are generated. When the alkaline earth metal compound is present on the surface of the construction material, the released fluorine immediately reacts with the alkaline earth metal compound, so that the fluorine can be effectively eliminated.

  If the moisture content is less than 0.5% by mass, the alkaline earth metal compound is not adsorbed on the surface of the construction material because the moisture content is low. If the moisture content exceeds 3% by mass, the moisture content is too high. Alkaline earth metal compounds are difficult to adhere uniformly to the surface of construction materials. In any case, unevenness in the fluorine non-eluting effect tends to occur, and there are cases where prevention of fluorine elution from the treated soil is not sufficient.

  An alkaline earth metal compound is added to the granulated material after the drying treatment (st4) to prepare a construction material. The adding step is, for example, by adding a certain amount of the alkaline earth metal compound stored in the silo to the granulated product discharged through the drying treatment with a quantitative feeder.

  The alkaline earth metal compound used in the present invention is preferably a calcium compound and / or a magnesium compound, such as calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, or a combination thereof. More preferably, magnesium oxide, magnesium hydroxide, or a combination thereof, more preferably magnesium oxide is used. This is because when a compound is formed with fluorine, the effect of non-eluting is high and the risk of exothermic reaction during storage and handling is low.

  The alkaline earth metal compound is preferably added in an amount of 3 to 25 parts by mass with respect to 100 parts by mass of the incinerated ash granulated product after the drying treatment. If it is less than 3 parts by mass, the effect of suppressing fluorine eluted when mixed with mud is not sufficient, and if it exceeds 25 parts by mass, there is no significant difference in the effect, so the economic efficiency deteriorates, which is not preferable.

  After the alkaline earth metal compound is added, the performance of the construction material may be deteriorated due to moisture absorption from the outside air. Therefore, the alkaline earth metal compound is preferably stored in a packaging container with little moisture fluctuation.

  The construction material thus obtained conforms to the aggregate screening test specified in JIS A1102, passes through a sieve with a nominal opening of 8 mm specified in JIS Z8801-1, and does not pass through a sieve with a nominal opening of 106 μm. It is prepared so that the mass ratio of a thing may be 60 mass% or more of the whole.

  If it is less than 60% by mass, the specific surface area in contact with carbon dioxide cannot be adjusted to such an extent that fluorine taken in the ettringite crystal structure is prevented from being destroyed by carbon dioxide, and an alkaline earth metal compound is added. Since the surface of the granulated material is not adequately adhered, the obtained construction material cannot effectively suppress the elution of fluorine from the treated soil after mixing with the mud soil. In particular, in order to prevent the amount of fluorine elution measured by the dissolution test method based on the Ministry of the Environment Notification No. 18 of 2003 from the treated soil after mixing the construction material and mud, the construction material must not exceed 0.8 mg / L. Therefore, it is necessary to make the fluorine non-eluting effectively. In addition, the more particles having a small particle diameter, the more easily dust is generated during use, and the use is not durable.

  According to the construction material of the present invention, by adding the alkaline earth metal compound to the granulated product after the drying treatment, the alkaline earth metal compound is not consumed by reaction with fluorine in the incineration ash, and the construction material Especially excellent for non-elution of fluorine from treated soil obtained after mixing mud. For this reason, the fluorine derived from mud and the alkaline earth metal compound react selectively, so that the elution of fluorine can be prevented, and the elution of fluorine from the treated soil can be suppressed below the soil environmental standard. In order to achieve non-elution of fluorine from the treated soil, simply mixing the granulated material and alkaline earth metal compound is not effective, and it is necessary to add the alkaline earth metal compound after granulation and drying. In addition, the particle diameter of the granulated product at the time of addition is preferably within a predetermined range.

  The construction material according to the present invention can be used for various applications such as soil improvement material, snow melting material, grassland improvement material, backfill material, embankment and the like.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to a following example.
(Examples 1-25, Comparative Examples 1-7)
As Examples 1 to 25 and Comparative Examples 1 to 7, incinerated ash, aluminum sulfate, cement, and water were mixed and granulated to obtain a granulated product. The granulated product was sieved and dried, and then the construction material was manufactured with or without the alkaline earth metal compound shown in Table 2 as an additive.
(Preparation of construction material of Example 1)
As a raw material for the construction material, paper sludge incinerated ash, aluminum sulfate, blast furnace cement, and water were blended in the proportions shown below. Aluminum sulfate and cement were used to insolubilize harmful substances in the incineration ash and adjust the strength of the construction material obtained by granulation. A reverse flow mixer (manufactured by Nihon Eirich Seisakusho) was used for mixing. Using this backflow mixer, mixing and granulation were performed for 10 minutes.

<Raw material formulation>
Papermaking sludge incineration ash 1000kg
Sulfuric acid band 200kg
Blast furnace cement 100kg
250 kg of water
Next, the obtained granulated material was sieved. A rotary sieving apparatus was used to screen out the soft granulated product so as not to make it fine. The sieve diameter of the sieve device was set to 3 mmφ. The large particle size separated by this sieving was crushed by a crusher and sieved again. The crusher used was a vertical axis. The average particle diameter of the granulated product was 0.5 mm.

  Next, the granulated product after sieving was cured. This curing was carried out in the presence of water to promote the reaction between the incinerated ash, aluminum sulfate and cement. The curing conditions were 24 hours at a temperature of 23 ° C. and a humidity of 50%.

  Furthermore, the granulated product after curing was dried using a horizontal fluidized bed dryer provided with a weir as shown in FIG. As drying conditions, hot air of 150 ° C. was used, and the average residence time inside the drying apparatus was 1 hour. The dried granulated material was obtained by the above process. The obtained granulated material was measured in accordance with an aggregate screening test specified in JIS A1102, passing through a sieve having a nominal aperture of 8 mm specified in JIS Z8801-1, and measuring an amount not passing through a sieve having a nominal aperture of 106 μm. . The results are shown in Table 2.

  As shown in Table 2, an alkaline earth metal compound was added to the dried granulated material to obtain a construction material. The addition amount described in Table 2 is expressed in parts by mass with respect to 100 parts by mass of dry mass of the incinerated ash granulated product. The obtained construction material was measured in accordance with an aggregate sieving test specified in JIS A1102, passing through a sieve having a nominal opening of 8 mm specified in JIS Z8801-1 and not passing through a sieve having a nominal opening of 106 μm. The results are shown in Table 2.

(Preparation of construction materials of Examples 2-5)
It was manufactured in the same manner as in Example 1 except that the addition amount of the alkaline earth metal compound was changed as shown in Table 2.

(Preparation of construction materials of Examples 6 to 20)
It manufactured like Example 1 except having changed the kind and addition amount of the alkaline-earth metal compound as shown in Table 2.

(Preparation of construction materials of Examples 21 to 24)
The time for drying the incinerated ash granulation was adjusted, the moisture content was adjusted as shown in Table 2, and the type and amount of the alkaline earth metal compound were changed as shown in Table 2. Manufactured.

(Preparation of construction material of Example 25)
Manufactured in the same manner as in Example 1 except that the type and amount of the alkaline earth metal compound were changed as shown in Table 2 and the alkaline earth metal compound was added even when mixing the raw materials in the granulated product production process (st1). .

(Preparation of construction materials of Comparative Examples 1 to 3)
Production was carried out in the same manner as in Example 1 except that the alkaline earth metal compound was not added.

(Preparation of construction materials for Comparative Examples 4 and 5)
After changing the kind and addition amount of the alkaline earth metal compound as shown in Table 2 and adding the alkaline earth metal compound to the raw material mixing (st1) in the granulated product production process, and drying the granulated product (st4) Was prepared in the same manner as in Example 1 except that no alkaline earth metal compound was added.

(Preparation of construction materials for Comparative Examples 6 and 7)
Manufacture was carried out in the same manner as in Example 1 except that the sieve diameter of the sieving apparatus used for the sieving treatment after granulation was set to 1 mmφ, and the kind and addition amount of the alkaline earth metal compound were changed as shown in Table 2.
(Effectiveness confirmation test)
The effect confirmation test was done about the construction material of each Example and each comparative example. In the effect confirmation test, the construction material of each example and each comparative example and mud (mud A, B, or C) are mixed at a mass ratio of 10: 100, and the amount of fluorine eluted from the soil after being mixed (treated soil), This was done by measuring the pH and earth resistance. As mud used for the effect confirmation test, mud of general environment was collected, and three kinds of mud (mud A, B, C) having different fluorine contents and pH were selected. Table 1 shows the fluorine content, fluorine elution amount, and pH of the eluate of each mud.

  The fluorine elution amount was measured by the dissolution test method based on the Ministry of the Environment Notification No. 18 in 2003, and the pH was measured by the test method based on the Ministry of the Environment Notification No. 46. The measured values are shown in Table 2. As a ground strength test, the treated soil was stepped on with a foot and evaluated based on the following evaluation criteria.

    ○: Treated soil is not deformed even if it is stepped on, and has excellent ground strength.

Δ: Soil is slightly deformed and the ground strength is poor when stepped on. ×: The soil is easily deformed and the ground strength is very poor when stepped on.

（評価結果）
酸化カルシウム、水酸化カルシウム、酸化マグネシウム、または水酸化マグネシウムを添加して調製した建設材料は、硫酸カルシウム、または硫酸マグネシウムを添加して調製した建設材料と比較して、フッ素溶出抑制効果が高い。特に水酸化カルシウムおよび水酸化マグネシウムに比べて酸化カルシウムおよび酸化マグネシウムの方が、また酸化カルシウムに比べて酸化マグネシウムの方が、添加によるフッ素溶出抑制効果が優れている。またｐＨが比較的高い泥土との混合では、酸化カルシウムを添加した建設材料を用いた場合に高ｐＨとなってしまうので、処理土の利用が制限される。したがって、かかる点からも酸化マグネシウムの添加が優れている。リン酸化合物は、フッ素溶出抑制効果を有するが、薬品コストが高くなるので好適には用いられない。造粒後の水分含有率を、０．５質量％未満、あるいは、３．０質量％を超過すると、水分含有率が０．５質量％〜３．０質量％の場合と比べて、フッ素溶出抑制効果が低下した。また、焼却灰混合時（ｓｔ１）にアルカリ土類金属化合物を添加すると、造粒物が硬く締まったために、泥土から水を吸収できず、処理土が軟弱となったため、耐地力が低下した。また、乾燥後（ｓｔ４）にアルカリ土類金属化合物を添加しない場合は、フッ素溶出抑制効果が低下した。建設材料の粒子径が１０６μｍ以上８ｍｍ以下の量が全体の６０質量％未満の建設材料は、６０％以上の建設材料と比べ、処理土のフッ素溶出が多く、フッ素溶出抑制効果が低下した。

(Evaluation results)
A construction material prepared by adding calcium oxide, calcium hydroxide, magnesium oxide, or magnesium hydroxide has a higher fluorine elution suppressing effect than a construction material prepared by adding calcium sulfate or magnesium sulfate. In particular, calcium oxide and magnesium oxide are superior to calcium hydroxide and magnesium hydroxide, and magnesium oxide is superior to calcium oxide in suppressing fluorine elution. In addition, mixing with mud having a relatively high pH results in a high pH when a construction material to which calcium oxide is added is used, so that the use of treated soil is limited. Therefore, addition of magnesium oxide is excellent also from this point. Phosphoric acid compounds have an effect of suppressing fluorine elution, but are not suitably used because the chemical cost increases. When the water content after granulation is less than 0.5% by mass or exceeding 3.0% by mass, the elution of fluorine is compared with the case where the water content is 0.5% by mass to 3.0% by mass. The inhibitory effect decreased. Moreover, when an alkaline earth metal compound was added at the time of incineration ash mixing (st1), since the granulated material was tightly tightened, water could not be absorbed from the mud, and the treated soil became soft, so the ground strength was reduced. Further, when no alkaline earth metal compound was added after drying (st4), the effect of suppressing fluorine elution was lowered. The construction material in which the particle diameter of the construction material is 106 μm or more and 8 mm or less is less than 60% by mass of the construction material has more fluorine elution from the treated soil than the construction material of 60% or more, and the fluorine elution suppression effect is reduced.

  When mud is treated with the construction material of the present invention, the elution of fluorine in the treated soil can be suppressed, so that the present invention can be used in the field of building materials. The construction material of the present invention can be used as, for example, a soil improvement material, a snow melting material, a grassland improvement material, a backfill material, and embankment.

It is a flowchart which shows the manufacturing method of the construction material of this embodiment. It is a figure which shows the specific structure of a horizontal type fluidized bed type drying apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ventilation plate 2 Weirs 3, 5 Fan 4 Heater 6 Silencer 7, 8 Conveyor 10 Granulated material 12 Horizontal fluid bed type dryer

Claims (6)

A construction material composed of incinerated ash granulated material mainly composed of incinerated ash, aluminum sulfate and cement, and an alkaline earth metal compound,
The incinerated ash granulated product is a step (a) of obtaining a granulated product by mixing the incinerated ash with the aluminum sulfate and the cement in the presence of water, and a step of drying the granulated product. Obtained through (b),
According to the aggregate screening test specified in JIS A1102, the mass ratio of the composition that passes through a sieve with a nominal opening of 8 mm specified in JIS Z8801-1 and does not pass through a sieve with a nominal opening of 106 μm is 60% by mass or more. A construction material characterized by that.   The construction material according to claim 1, wherein a moisture content of the incinerated ash granulated material is 3% by mass or less.   The construction material according to claim 1, wherein the alkaline earth metal compound is calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, or a combination thereof.   4. The construction according to claim 1, wherein the amount of the alkaline earth metal compound is 3 to 25 parts by mass with respect to 100 parts by mass of the dry mass of the incinerated ash granulated product. material.   The amount of fluorine elution measured by a dissolution test method based on the Ministry of the Environment Notification No. 18 of 2003 of the treated soil obtained by mixing the construction material and mud is 0.8 mg / L or less, The construction material according to any one of claims 1 to 4. A method for producing a construction material comprising a mixture of incinerated ash granulated material mainly composed of incinerated ash, aluminum sulfate and cement, and an alkaline earth metal compound,
The incinerated ash is subjected to a process of mixing the aluminum sulfate and the cement in the presence of at least water to obtain a granulated product, and a step of drying the granulated product (b), The manufacturing method of the construction material characterized by including the process of manufacturing incinerated ash granulated material, and the process of mixing the said incinerated ash granulated material and the said alkaline-earth metal compound in this order.

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