JP2008273993A - Heavy metal elution inhibitor and heavy metal elution-inhibiting construction method - Google Patents

Heavy metal elution inhibitor and heavy metal elution-inhibiting construction method Download PDF

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JP2008273993A
JP2008273993A JP2006216955A JP2006216955A JP2008273993A JP 2008273993 A JP2008273993 A JP 2008273993A JP 2006216955 A JP2006216955 A JP 2006216955A JP 2006216955 A JP2006216955 A JP 2006216955A JP 2008273993 A JP2008273993 A JP 2008273993A
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cement
heavy metal
reducing
hexavalent chromium
metal elution
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Hideaki Otsugi
英章 緒續
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TS SOLUTION Inc
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    • 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
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a hexavalent chromium elution inhibitor and a heavy metal elution-inhibiting construction method that can surely suppress elution of hexavalent chromium to an allowable value or lower, does not require the change of the construction method to comparatively expensive other construction methods such as a piling method and permits economical rapid execution. <P>SOLUTION: The heavy metal elution inhibitor comprises a reducing agent for converting hexavalent chromium in a known cement or a cement-solidifying material to trivalent chromium, a reducing auxiliary agent endowed with functions for maintaining a reducing atmosphere preventing trivalent chromium from changing to hexavalent chromium and, if required, a fixing agent endowed with fixing functions for chemically fixing chromium reduced to a trivalent state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description


本発明は、セメント並びにセメント系固化材用いた地盤改良土からの六価クロム等の重金属溶出抑制剤とそれを用いた溶出抑止方法に関する。
The present invention relates to an elution inhibitor for heavy metals such as hexavalent chromium from ground improved soil using cement and cement-based solidifying material, and a method for inhibiting elution using the same.


セメント並びにセメント系固化材は、六価クロム等のクロム化合物を含有しているため、これらの材料を用いた地盤改良土から、土質等の条件によっては、有害な六価クロムが環境基準（０．０５ｍｇ／Ｌ）を超えて溶出する。
このため、国は国直轄の全工事について、施工前に六価クロム溶出試験を行い、許容値を超える場合は、適切な措置を講じることとなった。
Since cement and cement-based solidified materials contain chromium compounds such as hexavalent chromium, depending on soil conditions, harmful hexavalent chromium from environmentally improved soils (0) .05 mg / L).
For this reason, the national government conducted a hexavalent chromium elution test before construction for all construction work under the direct control of the country, and took appropriate measures if it exceeded the allowable value.

この対策として、クロム含有量が少ない固化材や六価クロムを無害な三価クロムに還元する薬剤等が開発されたが、これらを用いても許容値をオーバーすることがあり、止む無く割高な杭打工などに工法変更を余儀なくされる場合が生じるなど問題がある。
これと前後して、セメントメーカーでは、従来のセメント系固化材のセメント分を２０％前後減らし六価クロムの少ない高炉スラグ等を混入することにより、六価クロム溶出量を削減できる固化材を開発し、特殊土用の「新型固化材」として販売している。 As countermeasures, solidification materials with low chromium content and chemicals that reduce hexavalent chromium to harmless trivalent chromium have been developed. However, even if these are used, the allowable value may be exceeded, and it is expensive. There is a problem that the construction method may be forced to change in pile driving.
Around this time, cement makers developed a solidified material that can reduce the amount of hexavalent chromium elution by reducing the cement content of conventional cement-based solidified materials by about 20% and mixing blast furnace slag with low hexavalent chromium. It is sold as a “new type solidification material” for special soil.

また、六価クロムを消滅させるため、還元剤を主剤とする手法が多々開発され産業廃棄物処理等に用いられている。
例えば硫酸第一鉄によって六価クロムを無害な三価クロムに還元する方法が開示されている（特許文献１、特許文献２、特許文献３）。
また還元剤として、塩化バリウムを使用する方法が開示されている(特許文献４、特許文献５、特許文献６)。また、亜硫酸ソーダを使用する方法が開示されている(特許文献７)。 In addition, in order to eliminate hexavalent chromium, many methods using a reducing agent as a main agent have been developed and used for industrial waste treatment and the like.
For example, a method of reducing hexavalent chromium to harmless trivalent chromium with ferrous sulfate is disclosed (Patent Document 1, Patent Document 2, and Patent Document 3).
Moreover, the method of using barium chloride as a reducing agent is disclosed (Patent Document 4, Patent Document 5, Patent Document 6). Further, a method using sodium sulfite is disclosed (Patent Document 7).

また、特殊土用の「新型固化材」は、許容値をクリアできない場合があり、改良土の強度も一般用固化材を下回る場合があることなどから、「新々固化材」の開発検討が行われている(例えば、特許文献８、特許文献９、特許文献１０、特許文献１１)。
また、クロムを吸着・固定する手法も検討され開示されている(例えば、特許文献１２)。 In addition, the “new type solidification material” for special soil may not be able to meet the allowable value, and the strength of the improved soil may be lower than that for general use. (For example, Patent Document 8, Patent Document 9, Patent Document 10, and Patent Document 11).
A technique for adsorbing and fixing chromium has also been studied and disclosed (for example, Patent Document 12).

しかし、実際の施工現場では「新固化材」の水準で施工しており、その改良技術は実用化には至っていない。
特開昭４７−３１８９４号公報 特開昭４９−１６７１４号公報 特開昭６２−６５７８７号公報 特開昭５５−１６１９５号公報 特開平１−９２１９３号公報 特開平１０−２３５１６号公報 特開２００５−１１２７０６号公報 特開平１０−２７９９３７号公報 特開２００４−２９２５６８号公報 特開２００４−２９９９７２号公報 特開２００５−３０６９１１号公報 特開２００５−１１２７０６号公報 However, the actual construction site is constructed at the level of “new solidified material”, and the improved technology has not been put to practical use.
JP 47-31894 A JP 49-16714 A JP-A-62-65787 JP 55-16195 A JP-A-1-92193 Japanese Patent Laid-Open No. 10-23516 JP-A-2005-112706 JP-A-10-279937 JP 2004-292568 A JP 2004-299972 A JP-A-2005-306911 JP-A-2005-112706


前記した従来の六価クロム溶出抑制剤とその抑止方法にあっては、次のような問題点がある。
（１）上記のような特殊土用の新型固化材を用いても土質条件等によっては基準値を超える場合がある。国交省の国直轄工事における平成１２年３月から１５年４月までの実態調査では新固化材を使用しても約２０%の箇所で許容値を超えている（非特許文献１）。
The above-described conventional hexavalent chromium elution inhibitor and its inhibiting method have the following problems.
(1) Even if a new type solidification material for special soil as described above is used, the standard value may be exceeded depending on the soil condition and the like. According to the actual survey from March 2000 to April 2015 in the work under the direct control of the Ministry of Land, Infrastructure, Transport and Tourism, even if newly solidified material is used, the allowable value is exceeded in about 20% (Non-Patent Document 1).

また、還元剤を主剤とする手法を地盤改良に用いても大きな効果は得られていない。
（２）したがって、これらの手法を用いても環境基準をクリアしない場合は、割高な杭打工などに工法変更を余儀なくされている。
（３）固化材の六価クロム量をさらに減らすためには、六価クロムを含有するセメントを減らし、高炉スラグ、石灰質材料等を増量する必要があるが、その場合セメント成分が減少するので、目的とする軟弱地盤の固化機能が低下する恐れがあり、セメント混合率の低下策には限界がある。
（４）六価クロムをほとんど含有しない固化材としては、従来より石灰が使われているが、固化機能特性から使用範囲が限られている。また新材料による固化材も検討されているが固化強度不足等のため実用化されていない(例えば、特許文献１３)。
（５）還元剤を主剤とする手法をセメント並びにセメント系固化材に用いた場合、六価クロムの溶出を多少減少させる効果はあるが、環境基準を満たすまでには至らない事例が多く、実用化されていない。 Moreover, even if the technique which uses a reducing agent as a main ingredient is used for ground improvement, the big effect is not acquired.
(2) Therefore, if the environmental standards are not cleared even if these methods are used, the construction method is forced to be changed to expensive pile driving or the like.
(3) In order to further reduce the amount of hexavalent chromium in the solidified material, it is necessary to reduce the cement containing hexavalent chromium and increase the amount of blast furnace slag, calcareous material, etc. There is a possibility that the solidification function of the intended soft ground may be lowered, and there are limits to the measures to lower the cement mixing rate.
(4) As a solidifying material containing almost no hexavalent chromium, lime has been used conventionally, but the range of use is limited due to the solidifying functional characteristics. Further, a solidified material using a new material has been studied, but has not been put into practical use due to insufficient solidification strength (for example, Patent Document 13).
(5) When the method using a reducing agent as the main component is used for cement and cement-based solidified material, it has the effect of reducing the elution of hexavalent chromium to some extent, but there are many cases where it does not meet the environmental standards and is practical. It has not been converted.

上記のようなことから、本発明者はセメントの固化と六価クロムの消長のメカニズムについて鋭意研究を続けた結果、次のようなことが明らかになった。
（１）セメント並びにセメント系固化材に一定量の還元剤を添加すると六価クロムは三価クロムに変化し、溶出しない筈である。しかし、公知のように六価クロムは還元雰囲気では三価クロムになり、その三価クロムは酸化雰囲気で六価クロムヘと可逆的に変化する性質がある。このため、セメントの固化進行に伴い還元雰囲気が酸化雰囲気に変わり、三価クロムが六価クロムになって溶出するものと考えられる。
（２）関東ローム土の場合、六価クロム溶出量は養生日数が３日と７日の比較では３日のほうが大きいと報告されている(非特許文献２)。
（３）しかし関係が深いと見られる混合後のpHと六価クロム溶出量の状況や３日までの経緯が解らず、メカニズムも解明できないため、本発明者が混合後のpHと六価クロム溶出量の時問的変化の実験を行った。
（４）これによると、表３の（１）のように、セメント系固化材、土、水、に１％の還元剤(硫酸第１鉄)を添加すると、その直後に六価クロムは不検出となった。しかし、時間の経過とともにその量は増加し、混合後１日目には０．０６ｍｇ／Ｌ、３日目には０．２１ｍｇ／Ｌと、無添加時の約１/２まで上昇してピークを迎え、その後固化のためか０．１８ｍｇ／Ｌと若干低下するがそのまま推移することが判明した。
（５）また、比較案として表３の（２）のように、還元剤を添加しない固化材のみの実験でも、六価クロムは混合時に０．２２ｍｇ／Ｌであったものが、３日後には約２倍の０．５１ｍｇ／Ｌ、８日後には０．３９ｍｇ／Ｌと数値は高いがほぼ同じ傾向を示している。また、本発明者が実施した関連実験によると、条件により変わるが、３日から６日の間でピークになることが確かめられている。 From the above, the present inventor has conducted earnest research on the mechanism of cement solidification and the decay of hexavalent chromium, and as a result, the following has been clarified.
(1) When a certain amount of reducing agent is added to cement and cement-based solidified material, hexavalent chromium is changed to trivalent chromium and should not be eluted. However, as is well known, hexavalent chromium becomes trivalent chromium in a reducing atmosphere, and the trivalent chromium has a property of reversibly changing to hexavalent chromium in an oxidizing atmosphere. For this reason, it is considered that as the cement solidifies, the reducing atmosphere is changed to an oxidizing atmosphere, and trivalent chromium is eluted as hexavalent chromium.
(2) In the case of Kanto loam soil, it has been reported that the hexavalent chromium elution amount is larger on the 3rd in comparison with the 3rd and 7th curing days (Non-patent Document 2).
(3) However, since the situation of pH and hexavalent chromium elution amount after mixing, which seems to be closely related, and the process up to 3 days cannot be understood and the mechanism cannot be clarified, the present inventor has determined the pH after mixing and hexavalent chromium. Experiments were conducted on the temporal change in the amount of elution.
(4) According to this, as shown in Table 3 (1), when 1% reducing agent (ferrous sulfate) is added to cement-based solidified material, soil and water, hexavalent chromium is not immediately after that. It became detection. However, the amount increased with the passage of time, peaked at 0.06 mg / L on the first day after mixing, and 0.21 mg / L on the third day, rising to about 1/2 without addition. After that, it was found that the temperature remained as it was, although it decreased slightly to 0.18 mg / L due to solidification.
(5) Further, as shown in Table 3 (2) as a comparative plan, even in the experiment using only the solidifying material to which no reducing agent was added, the hexavalent chromium was 0.22 mg / L at the time of mixing. Is about twice as high as 0.51 mg / L, and after 8 days it is 0.39 mg / L, showing a high value but almost the same tendency. Further, according to a related experiment conducted by the present inventor, it has been confirmed that the peak occurs between 3 and 6 days, although it varies depending on conditions.

（６）また、カオリン粘土の場合も表４に示す如く、固化剤のみの実験でも、六価クロムは混合時に０．０９ｍｇ／Ｌであったものが、３日後には０．１２ｍｇ／Ｌ、８日後には０．０８ｍｇ／Ｌとほぼ同じ傾向を示している。 (6) In the case of kaolin clay, as shown in Table 4, even in the experiment using only the solidifying agent, the hexavalent chromium was 0.09 mg / L at the time of mixing, but after 3 days it was 0.12 mg / L, After 8 days, it shows almost the same tendency as 0.08 mg / L.

（７）また、固化土の六価クロム溶出量は、固化による物理的固定作用などにより、長期的には徐々に低下してゆくことが確かめられている（非特許文献１、第２０頁）。
（８）これは、セメント類は水和・固化過程で水酸化カルシウムを生成して液相は高アルカリ性になるため、還元剤で一旦は三価クロムに変化した六価クロムが再び六価に舞戻るばかりでなく、元来の三価クロムも六価クロムに変化して六価クロム量が増大し、溶出量が大きくなるものと推定され、このセメント類の水和・固化過程と六価クロムの消長メカニズムを基づいた対策手法が必要であることが判明した。
（９）また、地盤改良における六価クロム溶出量は、土質により差があり、火山灰性粘土などの場合に大きい。これは、火山灰性粘土などに含まれる粘土鉱物が先行してセメント中のカルシウムを静電気的に引き寄せ吸着し、さらに粘土鉱物が六価クロムと同じ負電荷を持つため互いに反発して、六価クロムが外に追い出されるためとされているが、この粘土鉱物の特性をふまえた対策が必要である。
（１０）さらに最近においては、溶出量が許容値以下であっても、工事という人的行為により、人命に係わる六価クロムを新たに負荷させることが問題視されている。特に生活環境が重視される一戸建て新築住宅では、六価クロムが発生しない地盤改良工事が求められている。
特開２００５−３５０６３６号公報 国土交通省セメント系固化処理土検討委員会発行「セメント系固化処理土に関する検討最終報告書（案）」平成１５年６月３０日第６頁、第２頁 秋間健著、「セメント改良土からの六価クロム溶出原因の特定」財団法人環境地質科学研究所 研究年報第１３号 ２００２年 (7) Moreover, it is confirmed that the hexavalent chromium elution amount of the solidified soil gradually decreases in the long term due to a physical fixing action due to the solidification (Non-patent Document 1, page 20). .
(8) This is because cements produce calcium hydroxide during the hydration and solidification process, and the liquid phase becomes highly alkaline, so the hexavalent chromium once changed to trivalent chromium by the reducing agent becomes hexavalent again. Not only does it return, but the original trivalent chromium is also changed to hexavalent chromium, which increases the amount of hexavalent chromium and increases the amount of elution. It was found that a countermeasure method based on the chromic mechanism of chromium is necessary.
(9) Moreover, the amount of hexavalent chromium elution in ground improvement varies depending on the soil quality, and is large in the case of volcanic ash clay. This is because the clay minerals contained in volcanic ash clay etc. are preceded by electrostatically attracting and adsorbing calcium in the cement, and since the clay mineral has the same negative charge as hexavalent chromium, it repels each other, and hexavalent chromium Is said to be driven out, but it is necessary to take measures based on the characteristics of this clay mineral.
(10) More recently, even if the amount of elution is less than the allowable value, it has been regarded as a problem to newly load hexavalent chromium related to human life by a human act of construction. In particular, single-family homes where the living environment is emphasized require ground improvement work that does not generate hexavalent chromium.
JP-A-2005-350636 Issued by the Ministry of Land, Infrastructure, Transport and Tourism Cement-Based Solidified Soil Examination Committee, “Final Review Report on Cement-Based Solidified Soil (Draft)” June 30, 2003, pages 6, 2 Ken Akima, "Identification of the cause of hexavalent chromium elution from cement-modified soil" Research Institute for Environmental Geology, Annual Report 13, 2002


そこで本発明は、セメント中の六価クロムを三価クロムに変化させる還元剤、および三価クロムを六価クロムに変化させない還元雰囲気の維持機能を備えた還元助剤とよりなる重金属溶出抑制剤とするものである。
さらに、セメント中の六価クロムを三価クロムに変化させる還元剤、三価クロムを六価クロムに変化させない還元雰囲気の維持機能を備えた還元助剤、および三価になったクロムを化学的に固定する固定機能を備えた固定剤からなる重金属溶出抑制剤をとするものである。
Therefore, the present invention provides a heavy metal elution inhibitor comprising a reducing agent that changes hexavalent chromium in cement to trivalent chromium, and a reducing assistant that has a reducing atmosphere maintaining function that does not change trivalent chromium to hexavalent chromium. It is what.
Furthermore, reducing agents that change hexavalent chromium in cement to trivalent chromium, reducing assistants that maintain a reducing atmosphere that does not change trivalent chromium to hexavalent chromium, and trivalent chromium are chemically treated. A heavy metal elution inhibitor composed of a fixing agent having a fixing function for fixing to a metal.

さらに、本発明の重金属溶出抑制工法は、前記に記載の重金属溶出抑制剤を使用し、この重金属溶出抑制剤をセメント並びにセメント系固化材に添加混合して地盤土と撹拌・混合する重金属溶出抑制工法としたものである。     Furthermore, the heavy metal elution inhibitor construction method of the present invention uses the heavy metal elution inhibitor described above, and this heavy metal elution inhibitor is added and mixed with cement and cement-based solidified material and agitated and mixed with the ground soil. It is a construction method.


上記した構成によると、本発明の重金属溶出抑制剤およびその溶出抑制工法は、施工初期から施工完了（養生期間を含む。）までの間に六価クロムの溶出を許容値以下に確実に抑制することができ、杭打工などの割高な他工法への工法変更の必要がなく、経済的で迅速な施工が可能となる。
また、一般の固化材を使用して六価クロムの溶出量を不検出水準まで抑制することができ、強度への悪影響がないために、従前通りの設計のままで、施工初期から施工完了間での間六価クロム溶出許容値をクリアできるばかりでなく、添加量を増せば溶出量を減少できるので、溶出総量を減少させたいときには、特に効果を発揮する。
According to the above configuration, the heavy metal elution inhibitor and the elution control method of the present invention reliably suppress the elution of hexavalent chromium below the allowable value from the initial stage of construction to the completion of construction (including the curing period). Therefore, there is no need to change the construction method to an expensive construction method such as pile driving, and economical and quick construction is possible.
In addition, the elution amount of hexavalent chromium can be controlled to a non-detectable level by using a general solidifying material, and there is no adverse effect on strength. Not only can the hexavalent chromium elution allowance be cleared during this period, but the amount of elution can be reduced by increasing the amount added, which is particularly effective when the total amount of elution is to be reduced.


以下本発明の好適な実施の形態を詳細に説明する。
Hereinafter, preferred embodiments of the present invention will be described in detail.


本発明の重金属溶出抑制剤は、従来、施工初期に一旦は消滅した六価クロムがセメント類の水和・固化過程における高アルカリ化のため、還元雰囲気が低下して、施工中（養生中を含む。）にさらに量を増して生成されることを防ぐことを基本とし、万一発生した六価クロムは三価クロムに戻したあと化学的に固定して溶出を防ごうとするものである。
すなわち、セメント中の六価クロムを三価クロムに変化させる還元機能の還元剤と、三価クロムを六価クロムに変化させない還元雰囲気の維持機能を有する還元助剤と、三価クロムになったクロムを化学的に固定する固定機能を有する固定剤とからなるものであり、その３機能のうち、前の２機能と必要に応じて使用する固定機能を有する固定剤を提供するものである。
The heavy metal elution inhibitor of the present invention has conventionally been reduced in the reducing atmosphere due to the high alkalinity in the hydration / solidification process of the cements once the hexavalent chromium once disappeared in the initial stage of construction. In order to prevent elution, the generated hexavalent chromium should be chemically fixed after returning to trivalent chromium. .
That is, a reducing agent having a reducing function for changing hexavalent chromium in cement to trivalent chromium, a reducing agent having a reducing atmosphere maintaining function for not changing trivalent chromium to hexavalent chromium, and trivalent chromium. A fixing agent having a fixing function for chemically fixing chromium is provided, and among the three functions, the previous two functions and a fixing agent having a fixing function to be used as needed are provided.

また、かかる重金属溶出抑制剤を使用して、地盤の六価クロム溶出を抑制する工法である。
本発明の実施例をセメント系地盤改良の場合を例として説明する。
還元剤
本発明の還元剤は、硫酸第１鉄、塩化バリウム、硫酸バリウム、重亜硫酸ソーダ等を使用することができる。 In addition, the heavy metal elution inhibitor is used to suppress hexavalent chromium elution from the ground.
An embodiment of the present invention will be described by taking a cement-based ground improvement as an example.
Reducing agent For the reducing agent of the present invention, ferrous sulfate, barium chloride, barium sulfate, sodium bisulfite and the like can be used.

ただし、他の薬剤との反応がない、相性のよいもので、取り扱い易く安全なものがよい。
この観点から、硫酸第１鉄、硫酸バリウムがより好ましい。
添加量は、セメント中のクロム総量の相当量以上であればよく、一般に１〜４％程度である。 However, those that are compatible with other drugs and that are easy to handle and safe are preferred.
From this viewpoint, ferrous sulfate and barium sulfate are more preferable.
The addition amount may be equal to or greater than the total amount of chromium in the cement, and is generally about 1 to 4%.

還元剤はｐＨが３前後であり、還元雰囲気醸成にも効果があることやセメントと、土との混合時のロスを見込んで多めに設定する。
還元助剤
還元雰囲気維持剤(以下還元助剤という。)は、長期間還元状態を保持し、他の薬剤との反応がなく相性のよいものであれば良い。 The reducing agent has a pH of around 3, and is set to be large in consideration of the effect of fostering a reducing atmosphere and a loss during mixing of cement and soil.
Reducing aid A reducing atmosphere maintaining agent (hereinafter referred to as a reducing aid) may be any one that maintains a reduced state for a long period of time and does not react with other chemicals and has good compatibility.

この薬剤としては、長期間の薬効が必要であることから、有機酸を中心に用いる。
有機酸としては、解離すると負電荷を持ちアルカリとの中和反応を示すカルボキシル基、ケト基、水酸基、フェノール性水酸基等の酸官能基構造を有するものを使用するのがよい。
実施例では、乳酸、酢酸、アミノ酸、クエン酸、グルコン酸、およびその塩類、アルコール類、酵素等を調合し良い結果が得られた。 As this drug, since long-term efficacy is necessary, organic acids are mainly used.
As the organic acid, it is preferable to use an organic acid having an acid functional group structure such as a carboxyl group, a keto group, a hydroxyl group, and a phenolic hydroxyl group that has a negative charge when dissociated and exhibits a neutralization reaction with an alkali.
In the examples, lactic acid, acetic acid, amino acid, citric acid, gluconic acid, and salts thereof, alcohols, enzymes and the like were prepared, and good results were obtained.

配合比及び添加量は、セメントの固化過程のｐＨが１１、好ましくは１０台に保つことを条件に実験的に求めればよいが、原材料でセメント量の１〜２％程度が目途となる。
固定剤
固定剤は還元剤及び還元助剤だけでは阻止できなかった六価クロムを三価クロムにして化学的に固定し外部への溶出を防ぐもので、化学構造的にクロムを取り込み安定化する機能が認められ、固化機能を害さないものであればよい。 The blending ratio and addition amount may be obtained experimentally on the condition that the pH of the cement solidification process is maintained at 11, preferably 10 units, but about 1 to 2% of the cement amount is a raw material.
Fixing agent Fixing agent is made by converting hexavalent chromium, which could not be blocked by reducing agent and reducing aid alone, into trivalent chromium, and chemically fixing it to prevent elution to the outside. Any function that is recognized and does not impair the solidification function may be used.

公知のゼオライト等があるが、セメント系固化材は固化体の強度が最も重要であるので、固化強度を害しない機能性材料として、ＳｉＯ４ ４− 、ＨＳｉＯ４ ３−などの珪酸イオン水溶液を用いた。
この添加量は多いほど六価クロムに対し安全であり、強度も増加するが、適量は還元剤と還元助剤の六価クロム削減効果結果をみて実験的に決める必要がある。 There are known zeolites and the like. However, since the strength of the solidified material is the most important for cement-based solidified materials, silicate ion aqueous solutions such as SiO 4 4- and HSiO 4 3- are used as functional materials that do not impair the solidified strength. It was.
The larger the added amount, the safer the hexavalent chromium and the stronger the strength. However, the appropriate amount needs to be determined experimentally by looking at the effect of reducing the hexavalent chromium by the reducing agent and reducing aid.

実施例では原液でセメント量の１〜２０％の範囲である。
なお、この固定剤は必ずしも使用しなくてはならないものではない。
総合配合比
上記３種の薬剤の配合比は、その３機能の総合効果が最大になるよう土質等の条件毎に実験的に決められるが、六価クロムの溶出が最も大きい火山灰性粘土における配合比を基本にすれば安全側にある。 In an Example, it is the range of 1-20% of the amount of cement with a stock solution.
Note that this fixing agent is not necessarily used.
Total blending ratio The blending ratio of the above three chemicals is determined experimentally for each condition such as soil so that the total effect of the three functions is maximized, but it is blended in volcanic ash clay with the largest elution of hexavalent chromium. Based on the ratio, it is on the safe side.

表１に本発明で完成した溶出抑制剤を関東ローム土に対してセメント系固化材を使用した場合のｐＨと六価クロム溶出量(Cr6+)の時問的変化について示した。
表１の（１）、（２）の配合は、セメントもしくはセメント固化材に対して、還元剤３％、還元助剤（１）:０．５％、（２）:１％、固定剤５％である。 Table 1 shows the time-dependent changes in pH and hexavalent chromium elution (Cr 6+ ) when a cement-based solidifying material was used for the dissolution inhibitor completed in the present invention against Kanto loam soil.
The composition of (1) and (2) in Table 1 is 3% of reducing agent, reducing aid (1): 0.5%, (2): 1%, and fixing agent 5 with respect to cement or cement solidifying material. %.

また、表２にカオリン粘土に対してもセメント系固化材を使用した場合のｐＨと六価クロム溶出量(Cr6+)の時問的変化について示した。
表２の配合は、セメントもしくはセメント系固化材に対して、還元剤２％、還元助剤０．５％、固定剤２％である。 Table 2 shows the temporal changes in pH and hexavalent chromium elution (Cr 6+ ) when cement-based solidification material is used for kaolin clay.
The formulation in Table 2 is 2% reducing agent, 0.5% reducing aid, and 2% fixing agent with respect to cement or cement-based solidified material.

他の実施例を含めると、好ましい配合比は、火山灰性粘土の場合、セメントもしくはセメント系固化材の量に対し、還元剤１〜５％、還元助剤１〜２％、固定剤１以上であり、カオリン粘土の場合では、同様に、還元剤１〜２％、還元助剤０．５〜１％、固定剤１％以上である。
なお、上記各使用範囲において、上記した各最低値以下ではそれぞれの効果は期待できない。しかし、例えば、１％が０．９％や０．８％ではだめかというと必ずしもだめな数値ではなく、略１％という数値である。土木工事においては、セメントや使用土の量は膨大であり、その程度の数値の違いは生じることである。 When other examples are included, the preferable blending ratio is 1 to 5% of reducing agent, 1 to 2% of reducing aid, and 1 or more of fixing agent with respect to the amount of cement or cement-based solidifying material in the case of volcanic ash clay. Yes, in the case of kaolin clay, similarly, the reducing agent is 1 to 2%, the reducing aid is 0.5 to 1%, and the fixing agent is 1% or more.
In addition, in each said use range, each effect cannot be expected below each said minimum value. However, for example, if 1% is not good at 0.9% or 0.8%, it is not necessarily a bad numerical value, but a numerical value of approximately 1%. In civil engineering work, the amount of cement and soil used is enormous, and there is a difference in numerical values.

最高値は、還元剤は、１％程度でも量的にはよいが、少ないと反応時間が長くなるために５％としたもので、それ以上多くてもよい場合があるが、還元剤中の硫酸分の将来的影響を考慮するとあまり多量の使用は好ましくないと思われる。さらに、コストも、セメントの２０倍ほどであり、多量の使用は好ましくない。
還元助剤は、セメントの固化に悪い影響をおよぼすために多くの使用は好ましくなく２％程度を限度とした。 As for the maximum value, the amount of the reducing agent may be about 1%, but the amount may be 5% because the reaction time becomes long if the amount is small. Considering the future effects of sulfuric acid content, use of a large amount is not desirable. Furthermore, the cost is about 20 times that of cement, and a large amount of use is not preferable.
Reducing aids are unfavorable for many uses because they adversely affect cement solidification, and are limited to about 2%.

固定剤は、珪酸系であるためにカルシウムとの相性はよく、そのために多く使用してもかまわないものであるが、コストを考慮すると固定効果が生じる値で十分である。
これらの薬剤を実用化するためには、薬剤同士の反応や時間的経過によって薬効を低下させないように薬剤をいくつかのグループに分離して、粉体、液体の別を決め、さらに、セメントと土に混合する場合の混合順序などについて決める必要があるが、これもセメントと土の条件により実験的に決定する必要がある。 Since the fixing agent is silicic acid-based, it has a good compatibility with calcium. Therefore, the fixing agent may be used in a large amount, but considering the cost, a value that produces a fixing effect is sufficient.
In order to put these drugs into practical use, the drugs are separated into several groups so that the drug efficacy does not decrease due to the reaction between the drugs and the passage of time. It is necessary to determine the mixing order when mixing with soil, but this also needs to be determined experimentally according to the conditions of cement and soil.

実施例では、還元剤と還元助剤が粉体の場合は混合しても効果に問題はないが、固定剤は還元剤と反応するので単独収納とし、前者をセメントに混合してから時間差をおいて最後に投入する方法がよい。
還元剤と還元助剤が一方または両者が液体の場合は、還元剤の酸化を防ぐため、直前混合がよい。 In the examples, when the reducing agent and the reducing aid are powder, there is no problem even if they are mixed. However, since the fixing agent reacts with the reducing agent, it should be stored separately, and the time difference after mixing the former with cement. The last method is good.
When one or both of the reducing agent and the reducing aid are liquid, mixing immediately before is good in order to prevent oxidation of the reducing agent.

最終的には、現場の施工機械、施工方法や物流条件によって取り扱いを決めることになる。
地盤土との撹拌・混合
上記で説明した重金属溶出抑制剤を使用し、この重金属溶出抑制剤にセメントもしくはセメント系固化材を添加、混合して地盤土と撹拌・混合する。 Ultimately, the handling will be decided according to the construction machine, construction method and physical distribution conditions.
Agitation / mixing with ground soil Using the heavy metal elution inhibitor described above, cement or cement-based solidifying material is added to and mixed with the heavy metal elution inhibitor, and the ground soil is stirred and mixed.

この撹拌・混合方法は、公知のあらゆる地盤改良工法を利用することができる。
用途
本発明の六価クロム溶出抑制剤はこれを、クロムメッキ、生コンクリート工場およびコンクリート打設時の廃水、六価クロムを含む産業廃棄物や工場跡地における六価クロム溶出抑制対策として利用することができる。 Any known ground improvement method can be used for this stirring / mixing method.
Use The hexavalent chromium elution inhibitor of the present invention should be used as a countermeasure for suppressing hexavalent chromium elution in chrome plating, ready-mixed concrete factory and wastewater at the time of concrete placement, industrial waste containing hexavalent chromium and factory sites. Can do.

そのためには、六価クロム含有母材、含有量等による添加濃度、添加方法、処理物の撤去あるいは固定方法等の適切な施工法が必要となる。
また本発明の重金属溶出抑制剤はこれを、コンクリート構造物並びにコンクリート製品の六価クロム溶出抑制対策として利用することができる。
そのためには、六価クロム溶出抑制効果が最大となるよう薬剤の種類、配合比等を適切に調合すること、各薬剤の性質を考慮した混合方法や単位セメント量、水セメント比、六価クロム含有量、コンクリート構造物及びコンクリート製品の水分との接触状況等による添加濃度、添加方法等の適切な施工法が必要となる。 For this purpose, an appropriate construction method such as a hexavalent chromium-containing base material, an addition concentration depending on the content and the like, an addition method, a removal or fixing method of the processed material is required.
Moreover, the heavy metal elution inhibitor of this invention can be utilized as a hexavalent chromium elution suppression measure of a concrete structure and a concrete product.
For this purpose, appropriate types of chemicals, compounding ratios, etc. should be prepared to maximize the effect of inhibiting the dissolution of hexavalent chromium, mixing methods and unit cement amounts, water cement ratios, hexavalent chromium, taking into account the properties of each drug. Appropriate construction methods such as addition concentration and addition method depending on the content, contact status of concrete structures and concrete products with moisture, etc. are required.

また本発明の重金属溶出抑制剤はこれを、自然水域の水質改善の一環として利用することができる。
その場合は、六価クロムの削減・抑制効果が最大となるよう薬剤の種類、配合比、各薬剤の性質を考慮した混合方法、水中の六価クロム濃度、水のpH状況等による添加濃度、添加方法等などが必要となる。 Moreover, the heavy metal elution inhibitor of this invention can be utilized as part of the water quality improvement of a natural water area.
In that case, the type of drug, mixing ratio, mixing method that considers the properties of each drug, the concentration of hexavalent chromium in water, the concentration of water added depending on the pH status, etc. The addition method etc. are needed.

Claims (7)

セメント並びにセメント系固化材中の六価クロムを三価クロムに変化させる還元剤および三価クロムを六価クロムに変化させない還元雰囲気の維持機能を備えた還元助剤からなる重金属溶出抑制剤。 A heavy metal elution inhibitor comprising a reducing agent for changing hexavalent chromium in cement and cement-based solidified material to trivalent chromium, and a reducing aid having a reducing atmosphere maintaining function that does not change trivalent chromium to hexavalent chromium. 硫酸第１鉄、塩化バリウム、硫酸バリウム、重亜硫酸ソーダの内の１つからなる還元剤と、
カルボキシル基、ケト基、水酸基、フェノール性水酸基等の酸官能基構造を有する還元助剤とよりなる請求項１記載の重金属溶出抑制剤。 A reducing agent comprising one of ferrous sulfate, barium chloride, barium sulfate, and sodium bisulfite;
The heavy metal elution inhibitor according to claim 1, comprising a reducing aid having an acid functional group structure such as a carboxyl group, a keto group, a hydroxyl group, and a phenolic hydroxyl group. 請求項２において、セメントもしくはセメント系固化材の量に対し、還元剤１〜５％、還元助剤０．５〜２％である重金属溶出抑制剤。 The heavy metal elution inhibitor according to claim 2, wherein the reducing agent is 1 to 5% and the reducing aid is 0.5 to 2% with respect to the amount of cement or cement-based solidifying material. セメント並びにセメント系固化材中の六価クロムを三価クロムに変化させる還元剤、三価クロムを六価クロムに変化させない還元雰囲気の維持機能を備えた還元助剤、および三価になったクロムを化学的に固定する固定機能を備えた固定剤とからなる重金属溶出抑制剤。 Reducing agent that changes hexavalent chromium in cement and cement-based solidified material to trivalent chromium, reducing aid that maintains a reducing atmosphere that does not change trivalent chromium to hexavalent chromium, and trivalent chromium A heavy metal elution inhibitor comprising a fixing agent having a fixing function for chemically fixing a metal. 硫酸第１鉄、塩化バリウム、硫酸バリウム、重亜硫酸ソーダの内の１つからなる還元剤と、
カルボキシル基、ケト基、水酸基、フェノール性水酸基等の酸官能基構造を有する還元助剤と、
ＳｉＯ４ ４− 、ＨＳｉＯ４ ３−などの珪酸イオン水溶液からなる固定剤とよりなる請求項３記載の重金属溶出抑制剤。 A reducing agent comprising one of ferrous sulfate, barium chloride, barium sulfate, and sodium bisulfite;
A reduction aid having an acid functional group structure such as a carboxyl group, a keto group, a hydroxyl group, and a phenolic hydroxyl group;
SiO 4 4-, heavy metal elution inhibitor become more claim 3, wherein the fixing agent consisting of silicate ions aqueous solutions, such as HSiO 4 3-. 請求項５において、セメントもしくはセメント系固化材の量に対し、還元剤１〜５％、還元助剤０．５〜２％、固定剤１％以上である重金属溶出抑制剤。 The heavy metal elution inhibitor according to claim 5, wherein the reducing agent is 1 to 5%, the reducing auxiliary agent is 0.5 to 2%, and the fixing agent is 1% or more based on the amount of cement or cement-based solidifying material. 請求項１または請求項４に記載の重金属溶出抑制剤を使用し、
この重金属溶出抑制剤をセメントもしくはセメント系固化材に添加混合して地盤土と撹拌・混合する重金属溶出抑制工法。 Using the heavy metal elution inhibitor according to claim 1 or 4,
A heavy metal elution inhibitor construction method in which this heavy metal elution inhibitor is added to and mixed with cement or cement-based solidified material and stirred and mixed with the ground soil.
JP2006216955A 2006-08-09 2006-08-09 Heavy metal elution inhibitor and heavy metal elution-inhibiting construction method Pending JP2008273993A (en)

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JP2010150601A (en) * 2008-12-25 2010-07-08 Meltex Inc Method of treating chrome plated film
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010150601A (en) * 2008-12-25 2010-07-08 Meltex Inc Method of treating chrome plated film
JP2016191716A (en) * 2012-10-29 2016-11-10 太平洋セメント株式会社 Radioactive cesium removal method and burned product manufacturing method
WO2019093589A1 (en) * 2017-11-10 2019-05-16 조병학 Cement additive and method for producing same
DE112018005437T5 (en) 2017-11-10 2020-08-06 Byeong Hak Jo Cement aggregate and manufacturing process
JP2021502321A (en) * 2017-11-10 2021-01-28 ジョ, ビョン ハクJO, Byeong Hak Cement additive and its manufacturing method
US11214516B2 (en) 2017-11-10 2022-01-04 Byeong Hak Jo Cement additive and method for producing same
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