JP2014065659A - Cement-based solidification material using sludge dry powder and manufacturing method thereof - Google Patents
Cement-based solidification material using sludge dry powder and manufacturing method thereof Download PDFInfo
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- 239000010802 sludge Substances 0.000 title claims abstract description 89
- 239000000463 material Substances 0.000 title claims abstract description 51
- 239000004568 cement Substances 0.000 title claims abstract description 46
- 239000000843 powder Substances 0.000 title claims abstract description 42
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 238000007711 solidification Methods 0.000 title abstract description 17
- 230000008023 solidification Effects 0.000 title abstract description 17
- 238000002411 thermogravimetry Methods 0.000 claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims abstract description 9
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000000292 calcium oxide Substances 0.000 claims abstract description 6
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 239000011398 Portland cement Substances 0.000 claims description 6
- 239000010440 gypsum Substances 0.000 claims description 6
- 229910052602 gypsum Inorganic materials 0.000 claims description 6
- 239000002893 slag Substances 0.000 claims description 6
- 210000004556 brain Anatomy 0.000 claims 1
- 239000002689 soil Substances 0.000 abstract description 17
- 239000002002 slurry Substances 0.000 abstract description 16
- 230000003247 decreasing effect Effects 0.000 abstract description 2
- 239000002253 acid Substances 0.000 abstract 1
- 238000000034 method Methods 0.000 description 14
- 230000007423 decrease Effects 0.000 description 9
- 238000001035 drying Methods 0.000 description 7
- 230000036571 hydration Effects 0.000 description 7
- 238000006703 hydration reaction Methods 0.000 description 7
- 239000004606 Fillers/Extenders Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 230000004580 weight loss Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000012669 compression test Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- JLDKGEDPBONMDR-UHFFFAOYSA-N calcium;dioxido(oxo)silane;hydrate Chemical compound O.[Ca+2].[O-][Si]([O-])=O JLDKGEDPBONMDR-UHFFFAOYSA-N 0.000 description 1
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000007655 standard test method Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
Landscapes
- Treatment Of Sludge (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
Abstract
Description
本発明は、生コンクリート工場などから発生するコンクリートスラッジを有効利用したセメント系固化材に関し、特に固化材スラリーの流動性を低下させず、また固化処理土の強度が良好なセメント系固化材に関する。 The present invention relates to a cement-based solidified material that effectively uses concrete sludge generated from a ready-mixed concrete factory and the like, and more particularly, to a cement-based solidified material that does not decrease the fluidity of the solidified material slurry and has good strength of the solidified soil.
コンクリートスラッジ(以下、「スラッジ」という)は、生コンクリート工場、コンクリート製品工場などで副生する生コンクリートの洗い残渣、すなわち主としてセメントペーストおよび細骨材微粒部分からなる泥状の産業廃棄物である。これをセメント等の添加材として有効利用する場合、特に多量の水分が含まれることから、固形分の有効利用に際しては、品質の問題に加えて、輸送・運搬や処分時の法規制、経済性などの制約を解決する必要がある。特に、セメントの水和に伴う流動性の低下や強度低下の品質問題を解決しなければならない。 Concrete sludge (hereinafter referred to as “sludge”) is a washing residue of raw concrete produced as a by-product in ready-mixed concrete factories, concrete product factories, etc., that is, muddy industrial waste mainly composed of cement paste and fine aggregate fine particles. . When this is used effectively as an additive such as cement, it contains a large amount of water, so in addition to quality issues, it also has legal restrictions and economics during transportation / transportation and disposal. It is necessary to resolve such constraints. In particular, it is necessary to solve the quality problems of fluidity reduction and strength reduction due to cement hydration.
このような問題を解決する方法として、特許文献1には、スラッジを濾過脱水(フィルタープレス)し、加熱乾燥したのち、振動微粉砕してセメント未水和物を表面に出現させたセメント成分を含むスラッジ微粉を得る方法が開示されている。また、特許文献2には、スラッジ中のセメント水和物は吸水率が高いため、そのまま増量材として用いるとコンクリートのワーカビリチーが低下することから、スラッジの微粉部分を炭酸化する方法が開示されている。さらに、特許文献3には、スラッジの低い脱水乾燥効率と得られる粉粒体の粒度の限界を改善するために、風力粉砕する前に乾燥スラッジを予め破砕しておく方法が開示されている。 As a method for solving such a problem, Patent Document 1 discloses a cement component in which sludge is filtered and dehydrated (filter press), heated and dried, and then vibrationally pulverized to make cement unhydrated appear on the surface. A method of obtaining sludge fines containing is disclosed. Further, Patent Document 2 discloses a method for carbonating a fine powder portion of sludge because cement hydrate in sludge has a high water absorption rate, so that when used as an extender, the workability of concrete decreases. Yes. Further, Patent Document 3 discloses a method of previously crushing dried sludge before wind milling in order to improve the low dewatering drying efficiency of sludge and the limit of the particle size of the obtained granular material.
このような方法で得られたスラッジ乾燥粉は、コンクリートに用いられるセメントの増量材などに用いられる。しかし、たとえば、特許文献1に記載された方法により得られたスラッジを増量材として使用する場合、粘り気や材料の分離抵抗が高いものの、スラッジを砂の一部として約7〜10質量%の少量使用する場合にはコンクリートの圧縮強度を向上できる。しかし、セメントの一部として約23質量%もの比較的大量に使用する場合は圧縮強度を減少させてしまう。また、特許文献2に開示された方法により得られたスラッジを増量材として使用したコンクリートは、それを使用しないコンクリート製品と比較して遜色のない品質が得られているが、炭酸化処理は煩雑で経済的でない。また、これらのスラッジを土壌の安定化処理用のセメント系固化材に添加する場合、使用状況が異なることから、スラッジの性状によっては、それを添加した固化材スラリーの流動性の低下や固化処理土の強度低下を招く場合があり、あるいは処理工程が煩雑であり経済的でないことから、その有効利用が制限される場合がある。 The sludge dry powder obtained by such a method is used as a cement extender used in concrete. However, for example, when the sludge obtained by the method described in Patent Document 1 is used as an extender, a small amount of about 7 to 10% by mass with sludge as part of sand, although the stickiness and separation resistance of the material are high. When used, the compressive strength of concrete can be improved. However, when a relatively large amount of about 23% by mass is used as a part of the cement, the compressive strength is reduced. Moreover, although the concrete which used the sludge obtained by the method disclosed by patent document 2 as an extender has the quality comparable with the concrete product which does not use it, carbonation processing is complicated. It is not economical. In addition, when these sludges are added to cement-based solidification materials for soil stabilization treatment, the use conditions differ, so depending on the properties of the sludge, the fluidity of the solidification material slurry to which it is added or the solidification treatment In some cases, the strength of the soil may be reduced, or the effective use may be limited because the treatment process is complicated and not economical.
本発明は、スラッジを有効利用するとともに、スラリーの流動性の低下が少なく、且つ、性状の異なる各種の土壌に対して強度低下が少ないセメント系固化材およびその製造方法を提供することを目的とする。 An object of the present invention is to provide a cement-based solidified material that effectively uses sludge, has a small decrease in fluidity of slurry, and has a small decrease in strength with respect to various soils having different properties, and a method for producing the same. To do.
本発明者らは、上記課題を達成すべく種々検討した結果、スラッジ中のセメントを適度に水和させた後、脱水・加熱し、水和物の一部を脱水させたスラッジ乾燥粉を所定量添加したセメント系固化材が、固化材スラリーとしての適正な流動性を維持しつつ、性状の異なる各種の土壌に対し、十分な強度発現性を有することを知見した。また、そのスラッジ乾燥粉を得るための適正条件を見出した。すなわち、スラッジ中のセメントの水和の程度を、熱重量分析(TG)における400〜500℃における質量減少量と600〜800℃における質量減少量とを指標として表し、これらを制御することで、本発明の目的を達成することができることを知見した。 As a result of various studies to achieve the above-mentioned problems, the present inventors have obtained a sludge dry powder in which cement in sludge is appropriately hydrated and then dehydrated and heated to partially dehydrate the hydrate. It was found that the cementitious solidified material added quantitatively had sufficient strength development for various soils with different properties while maintaining proper fluidity as a solidified material slurry. Moreover, the suitable conditions for obtaining the sludge dry powder were found. That is, the degree of hydration of the cement in the sludge is expressed using the mass reduction amount at 400 to 500 ° C. and the mass reduction amount at 600 to 800 ° C. in thermogravimetric analysis (TG) as an index, and by controlling these, It has been found that the object of the present invention can be achieved.
本発明は、上記知見に基づいてなされたもので、本発明の目的に適うスラッジの指標として、熱重量分析(TG)における400〜500℃での質量減少量が0.5〜4.5%、600〜800℃での質量減少量が3.5〜8.5%であり、かつ、酸不溶残分(insol)を3〜10質量%、酸化カルシウムを45〜60質量%含み、ブレーン比表面積が5000〜10000cm2/gであるコンクリートスラッジ加熱乾燥粉である。本発明は、また、このコンクリートスラッジ加熱乾燥粉を2〜10質量%含むセメント系固化材である。本発明は、さらにまた、コンクリートスラッジ加熱乾燥粉の製造方法であって、コンクリートスラッジを、セメントが水と接触し始めてから、熱重量分析(TG)における400〜500℃での質量減少量が0.5〜4.5質量%、600〜800℃での質量減少量が3.5〜8.5質量%となるような時間内に取り出すと工程と、取り出したコンクリートスラッジを脱水する工程と、コンクリートスラッジの脱水物を600〜800℃の温度で加熱し、次いで粉砕する工程と、を含むコンクリートスラッジ加熱乾燥粉の製造方法である。 The present invention has been made based on the above findings, and as a sludge index suitable for the purpose of the present invention, the mass loss at 400 to 500 ° C. in thermogravimetric analysis (TG) is 0.5 to 4.5%. The amount of mass loss at 600 to 800 ° C. is 3.5 to 8.5%, the acid-insoluble residue (insol) is 3 to 10% by mass, calcium oxide is 45 to 60% by mass, A concrete sludge heat-dried powder having a surface area of 5000 to 10000 cm 2 / g. The present invention is also a cement-based solidified material containing 2 to 10% by mass of this concrete sludge heat-dried powder. The present invention is also a method for producing dry powder of concrete sludge, wherein the mass loss at 400 to 500 ° C. in thermogravimetric analysis (TG) is 0 after the cement sludge has started to come into contact with water. A step of removing the concrete sludge that has been taken out, and a step of dehydrating the taken-out concrete sludge; And heating the concrete sludge dehydrated material at a temperature of 600 to 800 ° C. and then crushing the dehydrated concrete sludge.
本発明によれば、従来、その多くが廃棄処分されていたスラッジをセメント系固化材の添加材として好適に有効利用することができる。また、本発明のセメント系固化材は、各種の軟弱地盤の安定処理に好適に使用することができる。 According to the present invention, sludge that has been disposed of in the past can be used effectively as an additive for cement-based solidifying materials. Moreover, the cement-type solidification material of this invention can be used suitably for the stable process of various soft grounds.
以下に、本発明のセメント系固化材およびその製造方法について詳細に説明する。 Below, the cement-type solidification material of this invention and its manufacturing method are demonstrated in detail.
本発明で使用するスラッジとは、生コンクリート工場、コンクリート製品工場などで発生する汚泥状物質である。主にアジテータ車のドラム内部に付着したモルタルや残コンクリート、戻りコンクリートの洗い残渣であり、セメント水和物や未水和物を含有する。スラッジ中の固形分は、セメントおよび高炉スラグのほか、フライアッシュや石灰石粉などの混和材が50〜95質量%含有され、残部が細骨材の微粒部からなる。このうち、セメント水和物はケイ酸カルシウム水和物(C−S−H)、水酸化カルシウムおよびカルシウムアルミノサルフェート水和物などである。また、通常、スラッジ水にはコンクリート用各種化学混和剤が溶解しているが、その存在が特に限定されるものではない。 The sludge used in the present invention is a sludge-like substance generated in a ready-mixed concrete factory, a concrete product factory, or the like. It is a washing residue of mortar, residual concrete, and return concrete mainly adhering inside the drum of an agitator car, and contains cement hydrate and non-hydrate. In addition to cement and blast furnace slag, the solid content in the sludge contains admixtures such as fly ash and limestone powder in an amount of 50 to 95% by mass, and the remainder consists of fine-grained fine aggregates. Among these, cement hydrates include calcium silicate hydrate (C—S—H), calcium hydroxide and calcium aluminosulfate hydrate. In addition, various chemical admixtures for concrete are usually dissolved in sludge water, but their presence is not particularly limited.
このようなスラッジを後述のように脱水し、加熱乾燥、解砕することにより、本発明のスラッジ乾燥粉が得られる。本発明のスラッジ乾燥粉中の水和状態を示す指標として、熱重量分析(TG)における400〜500℃での質量減少量が0.5〜4.5質量%、600〜800℃での質量減少量が3.5〜8.5質量%であり、好ましくは、400〜500℃での質量減少量が0.6〜4.0質量%、600〜800℃での質量減少量が4.0〜8.0質量%である。スラッジがこの範囲の質量減量値を示すとき、セメント水和が適切な状態にあること、およびその一部が脱水された化合物の含有量を示す指標となる。すなわち、熱重量分析(TG)において、400〜500℃では主にスラッジ中のセメント水和物であるCa(OH)2の分解が生じる。600〜800℃では、主にCaCO3の分解が生じる。400〜500℃での質量減少量が0.5質量%未満、600〜800℃での質量減少量が3.5質量%未満では、スラッジを固化材に添加した場合、固化処理土の強度発現が十分でなく、一方、400〜500℃での質量減少量が4.5質量%を超え、600〜800℃での質量減少量が8.5質量%を超えると、スラッジを添加した固化材の流動性の低下が大きくなるとともに、固化処理土の強度も低下するため好ましくない。スラッジの加熱乾燥粉の強熱減量をこの範囲に制御するためには、後述のように、スラッジの接水時間や乾燥温度を適切に制御する必要がある。 The sludge dry powder of the present invention is obtained by dehydrating such sludge as described below, drying by heating and crushing. As an index indicating the hydration state in the sludge dry powder of the present invention, the mass loss at 400 to 500 ° C. in thermogravimetric analysis (TG) is 0.5 to 4.5 mass%, and the mass at 600 to 800 ° C. The amount of reduction is 3.5 to 8.5% by mass, preferably the amount of mass reduction at 400 to 500 ° C. is 0.6 to 4.0% by mass, and the amount of mass reduction at 600 to 800 ° C. is 4. It is 0-8.0 mass%. When the sludge shows a weight loss value in this range, it becomes an index indicating that the cement hydration is in an appropriate state and the content of the partially dehydrated compound. That is, in thermogravimetric analysis (TG), at 400 to 500 ° C., decomposition of Ca (OH) 2 that is cement hydrate in sludge mainly occurs. At 600 to 800 ° C., mostly decomposition of CaCO 3 occurs. When the mass reduction amount at 400 to 500 ° C. is less than 0.5 mass% and the mass reduction amount at 600 to 800 ° C. is less than 3.5 mass%, when sludge is added to the solidified material, the strength expression of the solidified soil is exhibited. On the other hand, if the mass loss at 400 to 500 ° C. exceeds 4.5% by mass and the mass loss at 600 to 800 ° C. exceeds 8.5% by mass, the solidified material to which sludge has been added This is not preferable because the decrease in fluidity of the soil increases and the strength of the solidified soil also decreases. In order to control the loss on ignition of the sludge heat-dried powder within this range, it is necessary to appropriately control the water contact time and the drying temperature of the sludge as will be described later.
本発明のスラッジ乾燥粉中の酸不溶残分(insol)は3〜10質量%であり、好ましくは、5〜8質量%である。酸不溶残分が3質量%未満では、固化材スラリーの流動性の低下が大きく、一方、10質量%を超えると固化材の強度発現性が低下するため好ましくない。スラッジの加熱乾燥粉の酸不溶残分をこの範囲に制御するには、コンクリートに用いるセメント鉱物組成の選定や洗浄対象となるコンクリートの単位セメント量を管理することで制御することができる。 The acid-insoluble residue (insol) in the sludge dry powder of the present invention is 3 to 10% by mass, preferably 5 to 8% by mass. If the acid-insoluble residue is less than 3% by mass, the fluidity of the solidified material slurry is greatly reduced. On the other hand, if it exceeds 10% by mass, the strength developability of the solidified material is lowered, which is not preferable. In order to control the acid-insoluble residue of the heat-dried powder of sludge within this range, it can be controlled by selecting the cement mineral composition used for the concrete and managing the unit cement amount of the concrete to be cleaned.
また、本発明のスラッジ加熱乾燥粉中の酸化カルシウムは45〜60質量%であり、好ましくは、48〜55質量%程度である。酸化カルシウムの含有量が45質量%未満であると、相対的にセメント成分の含有量が少なく、スラッジ加熱乾燥粉を添加した固化材の強度発現性が低下する。また、60質量%を超えると、固化材スラリーの流動性の低下が大きくなることから好ましくない。スラッジ加熱乾燥粉中の酸化カルシウムをこの範囲に制御するには、酸不溶残分と同様にして制御する。 Moreover, the calcium oxide in the sludge heat dried powder of this invention is 45-60 mass%, Preferably, it is about 48-55 mass%. When the content of calcium oxide is less than 45% by mass, the content of the cement component is relatively small, and the strength development property of the solidified material to which the sludge heat-dried powder is added decreases. Moreover, when it exceeds 60 mass%, since the fall of the fluidity | liquidity of a solidification material slurry becomes large, it is unpreferable. In order to control the calcium oxide in the sludge heat-dried powder within this range, it is controlled in the same manner as the acid-insoluble residue.
さらに、本発明のスラッジ加熱乾燥粉のブレーン比表面積は5000〜10000cm2/gであり、より好ましくは6000〜9000cm2/gである。ブレーン比表面積が5000cm2/g未満では、スラッジ加熱乾燥粉を添加した固化材の強度発現性が低下する。また、10000cm2/gを超えると、スラッジ加熱乾燥粉を添加した固化材のスラリーの流動性の低下が大きく好ましくない。スラッジ加熱乾燥粉のブレーン比表面積をこの範囲に制御するには、セメントの接水時間のほか、スラッジの分級、加熱・乾燥時の粉砕時間などが挙げられる。 Furthermore, the Blaine specific surface area of the sludge heating dry powder of the present invention is 5000~10000cm 2 / g, more preferably 6000~9000cm 2 / g. When the Blaine specific surface area is less than 5000 cm 2 / g, strength development of the solidified material to which the sludge heat-dried powder is added is lowered. Moreover, when it exceeds 10,000 cm < 2 > / g, the fall of the fluidity | liquidity of the slurry of the solidification material which added the sludge heat dried powder is not preferable. In order to control the Blaine specific surface area of the sludge heat-dried powder within this range, in addition to the water contact time of cement, classification of sludge, grinding time during heating and drying, and the like can be mentioned.
本発明のスラッジ加熱乾燥粉は、セメント系固化材に2〜10質量%、好ましくは3〜7質量%添加する。スラッジ加熱乾燥粉の添加量が2質量%未満である場合、スラッジの有効利用の観点から十分でなく、10質量%を超えて添加した場合、固化材スラリーの流動性が低下するかあるいは固化強度の低下が過大となる。 The sludge heat-dried powder of the present invention is added to the cement-based solidified material in an amount of 2 to 10% by mass, preferably 3 to 7% by mass. When the amount of sludge heat-dried powder is less than 2% by mass, it is not sufficient from the viewpoint of effective use of sludge, and when it is added in excess of 10% by mass, the fluidity of the solidified slurry decreases or the solidification strength. The reduction of is excessive.
本発明のスラッジ加熱乾燥粉を2〜10質量%含む固化材スラリーは、水/固化材の質量比が0.4〜1.2、好ましくは0.5〜1.0で用いられる。0.4未満であるとスラリー施工に必要な流動性が得られず、1.2以上であると材料分離や固化処理土の強度低下が問題となる場合がある。 The solidified material slurry containing 2 to 10% by mass of the sludge heat-dried powder of the present invention is used at a water / solidified material mass ratio of 0.4 to 1.2, preferably 0.5 to 1.0. If it is less than 0.4, the fluidity required for slurry construction cannot be obtained, and if it is 1.2 or more, material separation or strength reduction of the solidified soil may become a problem.
スラッジ加熱乾燥粉を上記の所定量添加するセメント系固化材は特に制限されないが、ポルトランドセメント80〜95質量%、残部が石膏類よりなるもの、または、ポルトランドセメント40〜60質量%、高炉スラグ20〜40質量%、残部が石膏類よりなるものが好適である。特に、高炉スラグを配合した後者の固化材は、六価クロムの溶出量を少なくすることができるのでより好ましい。ポルトランドセメントとしては、JIS R 5210−2003ポルトランドセメントに規定の各種セメントを好適に使用することができる。高炉スラグはブレーン比表面積で3000〜8000cm2/g程度のものが望ましい。石膏としては、排脱二水石膏、天然石膏、ふっ酸製造時の副生の無水石膏等が好適に用いられ、その適正な粒度はブレーン比表面積で3000〜6000cm2/g程度である。 The cement-based solidified material to which the predetermined amount of the sludge heat-dried powder is added is not particularly limited, but Portland cement is 80 to 95% by mass, the remainder is made of gypsum, or Portland cement is 40 to 60% by mass, blast furnace slag 20 What consists of -40 mass% and the balance consists of gypsum is suitable. In particular, the latter solidified material blended with blast furnace slag is more preferable because it can reduce the elution amount of hexavalent chromium. As the Portland cement, various types of cement specified in JIS R 5210-2003 Portland cement can be suitably used. The blast furnace slag preferably has a Blaine specific surface area of about 3000 to 8000 cm 2 / g. As the gypsum, expelled dihydrate gypsum, natural gypsum, anhydrous gypsum by-produced during the production of hydrofluoric acid, and the like are preferably used, and the appropriate particle size is about 3000 to 6000 cm 2 / g in terms of the specific surface area of branes.
本発明のスラッジ加熱乾燥粉は次のような方法で好適に製造することができる。すなわち、まず、スラッジを脱水する。脱水方法としては、公知のフィルタープレス、ドラムプレス、遠心脱水装置などを用いることができる。なかでもフィルタープレスの使用が、水分低下率の面から好ましい。 The sludge heat-dried powder of the present invention can be suitably produced by the following method. That is, first, sludge is dehydrated. As a dehydration method, a known filter press, drum press, centrifugal dehydrator or the like can be used. Among these, the use of a filter press is preferable from the viewpoint of the moisture reduction rate.
スラッジに含まれるセメント成分は含水状態において水和が継続的に進行する。この水和物は、スラッジの加熱乾燥過程で、一部が脱水する。この脱水物は、多量の水分を速やかに捕捉するとともに、それが添加されるセメント系固化材中のセメントの速やかな水和を促す可能性があり、水分の適正量を超過すると強度低下に繋がる。このため、スラッジの加熱・乾燥までの接水時間を、JIS R 5201 8.3.2(1)に示されるセメントの凝結試験における始発時間〜24時間とするのが望ましい。なお、凝結試験における始発時間とは、スラッジ中に含まれるコンクリートに使用したセメントの凝結試験における開始時間を意味し、セメントの種類、品質で異なる。 Hydration of the cement component contained in the sludge proceeds continuously in a water-containing state. This hydrate is partially dehydrated during the heat drying process of the sludge. This dehydrated product quickly captures a large amount of water, and may promote rapid hydration of the cement in the cement-based solidified material to which it is added. Exceeding the appropriate amount of water leads to a decrease in strength. . For this reason, it is desirable that the water contact time until the sludge is heated and dried is set to the initial time to 24 hours in the cement setting test shown in JIS R 5201 8.3.2 (1). The initial time in the setting test means the start time in the setting test of the cement used for the concrete contained in the sludge, and differs depending on the type and quality of the cement.
スラッジの加熱方法としては、従来から公知のロータリーキルン、熱風循環式乾燥器などを用いることができる。なかでも、ロータリーキルンの使用が処理効率の点で好ましい。乾燥したスラッジは同時に解砕して粉状化する。乾燥温度は600℃〜800℃で処理する。 As a method for heating the sludge, a conventionally known rotary kiln, hot air circulation dryer or the like can be used. Of these, the use of a rotary kiln is preferable in terms of processing efficiency. The dried sludge is simultaneously crushed and powdered. The drying temperature is 600 ° C to 800 ° C.
以下、本発明の実施例と比較例とを対比参照しながら、本発明を具体的に説明する。 Hereinafter, the present invention will be described in detail with reference to an example of the present invention and a comparative example.
使用したスラッジ加熱乾燥粉の熱重量分析(TG)試験結果、JIS R5201−1997、JIS R5202−1999による分析値を表1に示す。図1には、熱重量分析(TG)の減量曲線を示した。ここでは、セメントの接水時間を変えて、異なる熱重量分析(TG)の減量曲線を有するスラッジ乾燥粉を調製した。熱重量分析(TG)はセイコーインスツルメンツ(株)製 TG−DTA320型を用い、窒素気流中、昇温速度10℃/分で25℃から1000℃まで測定した Table 1 shows the thermogravimetric analysis (TG) test results of the used sludge heat-dried powder and the analysis values according to JIS R5201-1997 and JIS R5202-1999. FIG. 1 shows a thermogravimetric analysis (TG) weight loss curve. Here, sludge dry powder having different thermogravimetric analysis (TG) weight loss curves was prepared by changing the water contact time of the cement. Thermogravimetric analysis (TG) was measured from 25 ° C. to 1000 ° C. at a heating rate of 10 ° C./min in a nitrogen stream using a TG-DTA320 type manufactured by Seiko Instruments Inc.
これらのスラッジ加熱乾燥粉を、表3に示す添加量で固化材に添加・混合し、供試固化材を調製した。なお、固化材は、表2に示す割合で、普通ポルトランドセメント、高炉スラグおよびII型無水石膏を配合したものである。 These sludge heat-dried powders were added to and mixed with the solidified material in the addition amounts shown in Table 3 to prepare test solidified materials. The solidified material is a mixture of ordinary Portland cement, blast furnace slag and type II anhydrous gypsum in the proportions shown in Table 2.
調製した固化材を水/固化材比0.6の固化材スラリーとし、Haake社製 Rotovisco RV−1を用いてせん断速度とせん断応力との関係を測定し、せん断速度200S−1、400S−1および600S−1における見掛け粘度を測定した。その結果を表3および図2に示す。表3には、各試験結果について、スラッジ加熱乾燥粉無添加(0質量%)の見かけ粘度を100%とした場合の比率を併記した。 The prepared solidified material was used as a solidified material slurry having a water / solidified material ratio of 0.6, and the relationship between the shear rate and the shear stress was measured using a Hato Rotovisco RV-1, and the shear rates were 200 S −1 and 400 S −1. And the apparent viscosity at 600S- 1 . The results are shown in Table 3 and FIG. In Table 3, for each test result, the ratio when the apparent viscosity of no added sludge heated dry powder (0% by mass) is 100% is also shown.
固化強度試験は次の方法によった。すなわち、所定割合に配合した固化材を表4に示す3種類の試料土に所定の配合で添加し、ソイルミキサーで3分間混合した。一軸圧縮試験の供試体は、セメント協会標準試験方法JCAS L−01:2006「セメント系固化材による改良体の強さ試験方法」に準じ、径5cm×長さ10cmとした。一軸圧縮試験は、JIS A 1216−1998「土の一軸圧縮試験方法」に準じた。材齢は7日および28日とした。その結果を表5、図3に示す。表5には、各試験結果について、スラッジ加熱乾燥粉無添加(0質量%)の固化処理土の強度を100%とした場合の強度比率を併記した。 The solidification strength test was performed according to the following method. That is, the solidified material blended at a predetermined ratio was added to the three types of sample soil shown in Table 4 in a predetermined blend, and mixed for 3 minutes with a soil mixer. The specimens for the uniaxial compression test were 5 cm in diameter and 10 cm in length according to the Cement Association standard test method JCAS L-01: 2006 “Strength test method for improved body with cement-based solidified material”. The uniaxial compression test conformed to JIS A 1216-1998 “Soil uniaxial compression test method”. The age was 7 and 28 days. The results are shown in Table 5 and FIG. Table 5 also shows the strength ratio when the strength of the solidified soil without addition of sludge heat-dried powder (0% by mass) is defined as 100% for each test result.
スラリーの流動性試験(見掛け粘度試験)の結果より、本発明の固化材のスラリー(スラッジA、Cを3、5、7質量%添加)の見かけ粘度の平均値は、参考例1として示したスラッジ乾燥粉無添加の見かけ粘度比率を100%とした場合、せん断速度Gp*=400S−1で102〜114%にとどまり施工上の大きな問題は生じない(実施例1〜6)。一方、乾燥までの接水時間が32時間と長く、それによりセメントの水和が進み過ぎ熱重量分析における各温度域での質量減少が大きくなり、併せてブレーン比表面積も本発明の範囲を逸脱するスラッジDを3、5、7質量%添加した固化材スラリーの見かけ粘度比率の平均値は、約130%と高く、施工上の支障となることがわかる(比較例1〜3)。 From the results of the slurry fluidity test (apparent viscosity test), the average value of the apparent viscosity of the solidified material slurry of the present invention (addition of 3, 5, and 7 mass% of sludges A and C) is shown as Reference Example 1. When the apparent viscosity ratio with no added sludge dry powder is set to 100%, the shear rate Gp * = 400 S −1 is only 102 to 114%, and no major problem in construction occurs (Examples 1 to 6). On the other hand, the water contact time until drying is as long as 32 hours, which leads to excessive hydration of the cement, resulting in a large mass loss in each temperature region in thermogravimetric analysis, and the Blaine specific surface area also deviates from the scope of the present invention. It can be seen that the average value of the apparent viscosity ratio of the solidified slurry added with 3, 5, and 7% by mass of sludge D is as high as about 130%, which hinders construction (Comparative Examples 1 to 3).
また、固化試験結果より、本発明の固化材(スラッジA、Cを3、5、7質量%添加)による固化処理土の強度は、参考例1として示したスラッジ加熱乾燥粉無添加に比較して、やや増加もしくは低下するものの、強度比の平均値で95〜105%の範囲であり、実質的にスラッジ加熱乾燥粉無添加と大差ないことがわかる(実施例7〜24、参考例2〜4)。一方、上記のスラッジDを3、5、7質量%まで添加した固化材による固化処理土の強度は、平均値で参考例1の約92質量%に低下する場合があり、この場合は固化材量を増加しなければならないことかわかる(比較例4〜9、参考例2〜4)。 From the results of the solidification test, the strength of the solidified soil using the solidified material of the present invention (addition of 3, 5, and 7 mass% of sludge A and C) is compared with that of the sludge heat-dried powder addition as shown in Reference Example 1. However, although it is slightly increased or decreased, it is found that the average value of the strength ratio is in the range of 95 to 105%, which is not substantially different from the addition of no sludge heated dry powder (Examples 7 to 24, Reference Examples 2 to 2). 4). On the other hand, the strength of the solidified soil by the solidified material to which the sludge D is added up to 3, 5, and 7% by mass may be reduced to about 92% by mass of Reference Example 1 in average, in which case the solidified material It can be seen that the amount must be increased (Comparative Examples 4 to 9, Reference Examples 2 to 4).
Claims (4)
コンクリートスラッジを、セメントが水と接触し始めてから、熱重量分析(TG)における400〜500℃での質量減少量が0.5〜4.5質量%、600〜800℃での質量減少量が3.5〜8.5質量%となるような時間内に取り出すと工程と、
取り出したコンクリートスラッジを脱水する工程と、
コンクリートスラッジの脱水物を600〜800℃の温度で加熱し、次いで粉砕する工程と、を含むコンクリートスラッジ加熱乾燥粉の製造方法。 A method for producing dried concrete sludge powder,
The concrete sludge has a mass loss at 400 to 500 ° C. and a mass loss at 600 to 800 ° C. in thermogravimetric analysis (TG) after cement starts to come into contact with water. When taken out in a time such that it becomes 3.5 to 8.5% by mass,
Dehydrating the concrete sludge taken out;
Heating the concrete sludge dehydrated material at a temperature of 600 to 800 ° C., and then crushing it.
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