JP4150190B2

JP4150190B2 - Cement activity detection method

Info

Publication number: JP4150190B2
Application number: JP2002020475A
Authority: JP
Inventors: 正美矢田; 英一勝部
Original assignee: Kitagawa Iron Works Co Ltd
Current assignee: Kitagawa Iron Works Co Ltd
Priority date: 2002-01-29
Filing date: 2002-01-29
Publication date: 2008-09-17
Anticipated expiration: 2022-01-29
Also published as: JP2003222623A

Description

【０００１】
【発明の属する技術分野】
本発明は、セメントミルク、モルタル、生コンクリート、あるいはセメントを含んだ水等、各種検体中に存在する未固化状態のセメントの活性度検出方法に関する。
【０００２】
【従来の技術】
セメントミルク、モルタル、生コンクリート、あるいはセメントを含んだ水に存在するセメントの活性度を検出する方法としては、ポルトランドセメントの化学分析方法（ＪＩＳＲ５２０２）の中の強熱減量の定量方法に準じて前記試料を水に懸濁した後、０．６ｍｍと０．１５ｍｍの二つのふるいを通し、得られた濁水を吸引ろ過によって固液分離し、更に固形分をアセトン洗浄した後１０５℃で恒温状態になるまで乾燥させた試料について、測定される強熱減量を見ることで活性度の有無を推定できることが知られている。また、セメントを含んだスラッジ水中のセメントの活性度を検出する方法として、特開平１１−２２３６２８号公報によると、スラッジ水にグルコース等の還元糖を添加し、例えば酵素法によるとグルコースオキシダーゼ、ペルオキシダーゼ及びｏ−トリジンからなる反応試薬で呈色反応させて前記還元糖の存在を検出し、セメントの活性度を間接的に検査するものが開示されている。
【０００３】
【発明が解決しようとする課題】
前記ポルトランドセメントの化学分析方法（ＪＩＳＲ５２０２）の強熱減量を定量するセメント活性度の検査方法は時間と熟練を要すると共に、計量器及び乾燥機などの機器を使用するため現場において実施することが困難である。また、添加した還元糖を呈色反応により検出する特開平１１−２２３６２８号公報に開示された方法は、基本的に呈色の有無を目視するものであり、記録あるいは結果に基づいた制御等の自動化に適していない。また、還元糖の添加が不可欠であり反応試薬も使い捨てであるため、多くの検体に実施する場合には好ましい方法とはいえず、更に使用する酵素の失活防止等、使用する反応試薬の管理及び長期保存に留意が必要である。
本発明は、これらの問題を解決するためになされたもので、各種検体中に存在するセメントの活性度を簡便に検出する方法を提供することにある。
【０００４】
【課題を解決するための手段】
上記事情に鑑み鋭意検討した結果、出願人は、セメントの活性度が特定の金属材料で構成された電極間を流れる電流値の変動パターンと相関があることを見出し本発明を完成するに至った。即ち、本発明は、セメントミルク、モルタル、生コンクリート、あるいは少なくともセメントを含んだ水等に存在するセメントの活性度検出方法であって、陽極及び陰極とからなる少なくとも一対の検出用電極を使用し、該検出用電極が、少なくとも陽極には、電極表面へ酸化被膜を生成しやすい不動態化金属を用い、前記検出用電極間に電圧を印加する際に流れる電流値を測定し、電圧印加直後の電極表面の酸化被膜生成に起因する電流値の変動パターンに基づいてセメントの活性度を判断するセメントの活性度の検出方法である。
本発明に係るセメントの活性度の検出については未だ不明な点もあるが、陽極にアルミニウム等を用い、水酸化ナトリウムあるいは水酸化カルシウム等のアルカリ溶液中で電圧を印加すると、直ちに電極表面の酸化被膜生成に起因すると考えられる電流値の急激な低下（不動態化現象という）を示すことが確認できる。（このときに使用するアルミニウム等の金属を不動態化金属と呼ぶ。）同じアルカリ溶液であるセメントを含んだ試料についてもセメントの水和反応が終了した試料については、前記電流値の低下現象が認められたが、唯一セメントの水和反応が終了していない活性度が残存する試料についてのみ、何らかの要因が作用し電流値の低下が起きないことを見出し、セメントの活性度を検出する方法として発展させたものである。
【０００５】
【発明の実施の形態】
本発明に係るセメントの活性度の検出装置の基本構成は、陽極と陰極からなる検出用電極と、電圧印加用の電源手段と、電流値のモニターなどを備える。
検出用電極は電流値の変動パターンを測定できるものであればよく、形状、大きさ、電極間距離には特に制限はないが、陽極は酸化被膜を生成しやすい不動態化金属を使用する。陽極には、特に、入手及び加工のしやすさからアルミニウムを含有する金属材料が好ましい。また、陰極は陽極と同じ材料でも、異なる材料でも使用できる。
次に、検出用電極の内、陽極の電極機能を回復させるための洗浄手段として陽極の極性反転を実施し、陽極を一時的に陰極に転換できるようにする。この際、検出用電極を構成する陽極と陰極の極性を入れ換えてもよく、また、検出用電極以外に補助電極を配置し、補助電極を陽極及び検出用電極を構成する両電極を陰極として電圧を印加することもできる。
前記電圧印加用の電源手段で印加する電圧は定電圧が好ましく、また、直流が好ましい。また、印加する電圧値は、検出用電極の大きさ、形状及び材質、更には検体の濃度及び性状を基に電流値の変動パターンが確認できる範囲で決定すればよく、通常、１Ｖ〜１００Ｖの範囲を使用する。
電流値の変動パターンは、通常電圧印加直後から２分以内の電流値の変動パターンを測定すればよい。
【０００６】
本発明の活性度の範囲とはセメントの固化反応の内、次の反応状態を示す。即ち、セメントの硬化反応は解明されていない部分があるが、まず、セメントと水が接すると一組成物の３ＣａＯ・Ａl_２Ｏ_３の表面に石膏（Ｃａ_２ＳＯ_４・２Ｈ_２Ｏ）によって微細なエトリンガイト結晶で緻密な被膜が作られ、３ＣａＯ・Ａl_２Ｏ_３の水和反応速度を一時的に抑制し、その一方で、３ＣａＯ・ＳｉＯ_２が３ＣａＯ・Ａl_２Ｏ_３と同様に水和反応を開始するが、やはり表面に薄い水和物の被膜を生じて水和反応が低調な状態がしばらく続く。普通ポルトランドセメントの場合、水と接してから４〜５時間このような状態が継続し、その後１０数時間にわたって３ＣａＯ・ＳｉＯ_２の最も活発な水和反応が起こり、セメント粒子の間隙が生成するＣＳＨゲル（カルシウム−シリケート−ハイドレート）等によって緻密に埋められながら固化が進行する。この水と接してから最も活発な水和反応が鎮静化するまでの状態を対象としている。
本発明で示すセメントの活性度の検出方法では、例えば、陽極をアルミニウム及び陰極を鉄から構成される検出用電極を用い、電極間に電圧を印加した場合、セメントの活性度に応じて電流値の変動パターンは、例えば、図１−(A)、図１−(B)、図１−(C)に代表されるような形となる。セメント分の活性が十分残存している場合の電流値の変動パターンは図１−(B) のように電流値はほぼ一定か図１−(A)のような上昇傾向を示す。一方、活性度が低下している場合の電流値の変動パターンは図１−(C)のように電圧印加直後から急激な低下傾向を示す。従って、検体に電極を挿入した際に図１−(A)、図１−(B)に示す様な電流値の変動パターンになることを確認するだけでセメントの活性度が残存することが簡単に分かる。
【０００７】
本発明の実施に当たっては携帯用の測定器とすることが可能で、例えば図２に示すように電流計２、記録計３を備えた電源手段１に陽極５及び陰極６から構成される検出用電極４を接続する。使用する際には、検体に検出用電極４を挿入するだけで簡単にセメントの活性度を確認できる。また、検出用電極を現場に設置し、管理室等のモニターで監視することも可能で、更に、電流値の変動パターンを記憶、演算処理する手段を用いることで一定時間内の電流値の変化量を数値化し、この数値に基づいて活性度を自動判定しランプの点灯等で表示したり、電気信号として記録あるいは種々の制御に反映することができる。例えば、本発明者らが開発したセメントを含むスラッジ水を電解処理し脱水処理する方法（特願２００１−３９６６７６号）において、電解処理を制御する際の手段に利用できる。
【０００８】
【実施例】
以下、実施例で本発明を説明する。
（実施例１）陽極及び陰極にアルミニウム板（厚さ１ｍｍ、縦横各10ｍｍ）を使用し、電極間隔10ｍｍのセメントの活性度の検出用電極を作成した。この電極間に１９Vの定電圧を印加する電源手段及び電流計を接続した測定器を作成し、試験に用いた。
普通ポルトランドセメント１重量部に対し砂３重量部、砂利（最大寸法２０ｍｍ）３重量部、水0.5重量部、コンクリート用化学混和剤（AE減水剤、商品名「ポゾリス78S」）0.015重量部を混練して調整した生コンクリートに前記検出用電極を挿入し、室温約２０℃の状態で静置した。挿入しておいた検出用電極に対して生コンクリートを調整してから５時間目、１０時間目、２０時間目、３０時間目にそれぞれ１分間電圧を印加した際の電流値の測定結果を図３に示す。図に示されるように５時間目及び１０時間目の電流値の変動パターンは、それぞれ上昇傾向及び一定となったが、２０時間目及び３０時間目の電流値の変動パターンは低下傾向を示した。また、前記試験とは別に各時間目の生コンクリート試料１００ｇ程度を採取し、５時間目及び１０時間目の試料については直接、また、固化が始まった２０時間目及び３０時間目の試料についてはハンマーで砕き砂利を除いた後にアセトン２L中に懸濁し吸引ろ過で回収後、１０５℃で恒温状態になるまで乾燥させた各試料の内０．１５ｍｍのふるいを通過したものについて、強熱減量をポルトランドセメントの化学分析方法（ＪＩＳＲ５２０２）に従い測定したところ、５時間目及び１０時間目の試料の強熱減量は、それぞれ２．１％、３．６％であり、一方、電流値の変動パターンが低下傾向を示した２０時間目及び３０時間目の試料の強熱減量は、それぞれ８．８％、１０．２％と結合水の量が多く水和反応がかなり進行していることが分かった。
尚、本試験例では生コンクリートの場合について説明したが、セメントミルク、モルタル等についても同様に測定できる。
本発明のセメント活性度の検出方法を用いることで、セメントミルク、モルタル及び生コンクリート等に存在するセメント活性度を簡便に検出でき、セメントの評価試験に有効である。また、社会的に問題となっているコンクリートのコールドジョイントの防止関連技術として利用できる。
【０００９】
（実施例２）陽極に厚み３ｍｍのアルミニウム板（浸漬面積：80×50mm）、陰極に厚み３ｍｍの鉄板（浸漬面積：80×50mm）から構成され、陽極及び陰極の電極間隔６cmのセメントの活性度の検出用電極を作成し、この電極間に６０Vの定電圧を印加する電源手段及び電流計を接続し試験に用いた。
試料は普通ポルトランドセメント１重量部に対し砂3重量部、砂利（最大寸法２０ｍｍ）３重量部、水0.5重量部、コンクリート用化学混和剤（AE減水剤、商品名「ポゾリス78S」）0.015重量部の生コンクリートを調整し、調整後３時間経過した生コンクリートに対し重量比で約５倍量の水を加えて作成したセメントを含んだスラッジ水を検体として使用した。尚、検体は撹拌機で撹拌しておき、随時１ｋｇ宛てをアクリル板で製作したL160×W120×H120mmの水槽に取り試験に用いた。
図４は前記スラッジ水作成から１時間、５時間、１５時間、２５時間経過したものに対して電圧を印加してから２分間の電流値の変動パターンを示したグラフである。図４から分かるように作成から１時間及び５時間経過したスラッジ水の電流値は上昇傾向を示すのに対して、１５時間、２５時間経過したスラッジ水は電流値の低下が見られた。また、前記試験とは別に各経過時間のスラッジ水から吸引ろ過によって固形分を集め、１週間後の一軸圧縮強度を確認したところ、スラッジ水作成から１時間及び５時間経過したものについては、それぞれ１７．６Ｎ／mm²、１５．８N／mm²を示し固化活性が十分に残存していたことが分かった。一方、１５時間及び２５時間経過したスラッジ水につては、それぞれ６．７Ｎ／mm²、５．８N／mm²であり固化活性が低下していたことが分かった。
尚、本試験例では生コンクリートから生じたスラッジ水の場合について説明したが、少なくともセメントを含んだ水、即ち、重金属が混入した廃水等に対し意図的にセメントを添加した水についても同様に測定できる。
【００１０】
（実施例３）実施例２で示したセメント活性度の検出用電極を用い、生コンクリート製造工場のスラッジ水槽から採取したスラッジ水（固形分濃度約６％、スラッジ水発生後からの経過時間不明）及び同工場のミキサー車洗車過程から採取したスラッジ水（固形分濃度約５％）に対して活性度の検出を試みた結果を図５に示す。図５に示されるようにスラッジ水槽から採取したスラッジ水の電流値の変動パターンは低下傾向を示し、ミキサー車洗車過程から採取したものは電流値の変動パターンが上昇傾向を示した。更に、前記試験とは別にスラッジ水槽及びミキサー車洗車過程から採取したスラッジ水について吸引ろ過によって固形分を集め、１週間後の一軸圧縮強度を確認したところ、スラッジ水槽から採取したスラッジ水につては、５．１N／mm²と低い値を示したのに対し、ミキサー車洗車過程のスラッジ水については、１４．２Ｎ／mm²の高い値となり十分な固化活性が残存していたことが分かった。
本発明のセメント活性度の検出方法を用いることで、生コンクリートの混練設備や残存した生コンクリートの処理工程から排出されるセメントを含んだスラッジ水を脱水処理し高強度のケーキを製造しリサイクルする際に、スラッジ水中のセメント活性度を時間的な判断ではなく、実際の活性度の有無として把握することが可能になり、安定的に高強度のケーキを得ることができる。また、前記スラッジ水を生コンクリートの練り水に再利用する際には、セメントの活性度の有無を電気信号として出力させることで遅延剤供給等の自動化が可能になる。
【００１１】
（実施例４）実施例２で示したセメントの活性度の検出用電極を用い、実施例２で作成したスラッジ水（スラッジ水作成から２５時間経過したもの）に対して測定時間１分間の活性度検出を５回連続して実施した。この時、前記検出用電極の陽極の極性反転を実施しない場合の結果を図６−(A)、及び活性度の検出後に毎回１分間の極性反転として陽極を陰極に、陰極を陽極とする転換を実施した場合の結果を図６−(B)に示す。実施例２と同様に作成から２５時間経過したスラッジ水は、本実施例においても電流値の変動パターンからいずれの場合もセメントの活性度が低いと判定されるが、極性反転を実施しない場合は、測定回数が増す毎に電圧印加直後の初期電流値が低下、つまり、検出用電極の電極機能の低下が見られるのに対し、極性反転を実施した場合は検出用電極の電極機能が回復することが分かる。
【００１２】
（実施例５）図７に示す様にセメントの活性度の検出用電極７を構成する陽極８に対向するように鉄板（浸漬面積：80×50mm）製の補助電極１０を設け、陽極８を中心に陰極９と補助電極１０がそれぞれ左右に配置されたセメントの活性度の検出用電極７を作成した。この検出用電極７を用い、実施例４と同様に測定時間１分間の活性度の検出を５回連続して実施した。この時、活性度の検出後に毎回１分間、検出用電極の陽極８を陰極とし、補助電極１０を陽極として６０Vの電圧を印加する極性反転を実施した場合の結果を図８に示す。実施例２と同様に２５時間経過したスラッジ水は、本実施例においても電流値の変動パターンから常にセメントの活性度が低いと判定されると共に、補助電極１０と検出用電極の陽極８との間で電圧を印加することで、検出用電極を構成する陽極の電極機能が回復することが分かる。
【００１３】
【発明の効果】
請求項１によれば、各種検体中のセメントの活性度が簡便に検出できるだけでなく、電流値の測定により電気信号として扱えることから記録の容易性、あるいは結果に基づいた後工程の制御等の自動化がきわめて容易になる。
請求項２によれば、検出用電極の内、少なくとも陽極に酸化被膜を生成しやすい不動態化金属を用いることで、セメント活性度がない場合の電流値の変動パターンがより明確になる。
請求項３によれば、検出用電極の内、少なくとも陽極にアルミニウムを含有する材質が利用できるため、電極材料の入手及び加工が容易になる。
請求項４及び請求項５によれば、電圧印加のみで検出用電極の電極機能が回復するため、１本の検出用電極で繰り返し使用できる。
【図面の簡単な説明】
【図１】A、Bは、セメントの活性度が十分残存している場合の電流値の変動パターンのグラフ。Cはセメントの活性度が低下している場合の電流値の変動パターンのグラフを示す。
【図２】電流値を測定する測定器の一例を示す概念図を示す。
【図３】混練後の経過時間に対する生コンクリート中の電流値の変動パターンのグラフを示す。
【図４】作成後の経過時間に対するスラッジ水中の電流値の変動パターンのグラフを示す。
【図５】検知体の違いによる電流値の変動パターンのグラフを示す。
【図６】検出用電極の陽極と陰極を転換した場合としない場合の電流値の変動パターンのグラフを示す。
【図７】補助電極を使用する場合の概念図を示す。
【図８】補助電極を用いて極性反転した場合の電流値の変動パターンのグラフを示す。
【符号の説明】
１電源手段
２電流計
３記録計
４,７検出用電極
５,８陽極
６,９陰極
１０補助電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for detecting the activity of unsolidified cement present in various specimens such as cement milk, mortar, ready-mixed concrete, or water containing cement.
[0002]
[Prior art]
As a method for detecting the activity of cement present in cement milk, mortar, ready-mixed concrete, or water containing cement, it is in accordance with the quantitative analysis method of loss on ignition in the chemical analysis method of Portland cement (JIS R 5202). The sample was suspended in water, passed through two sieves of 0.6 mm and 0.15 mm, and the resulting turbid water was separated into solid and liquid by suction filtration. Further, the solid content was washed with acetone and then kept at 105 ° C. It is known that the presence or absence of activity can be estimated by observing the measured loss on ignition of a sample dried to a state. Further, as a method for detecting the activity of cement in sludge water containing cement, according to JP-A-11-223628, a reducing sugar such as glucose is added to sludge water. For example, according to an enzymatic method, glucose oxidase, peroxidase In addition, there is disclosed a method in which the presence of the reducing sugar is detected by a color reaction using a reaction reagent comprising o-tolidine and the cement activity is indirectly examined.
[0003]
[Problems to be solved by the invention]
The cement activity inspection method for quantifying the loss on ignition of the Portland cement chemical analysis method (JIS R 5202) requires time and skill, and should be carried out in the field because it uses equipment such as a meter and a dryer. Is difficult. In addition, the method disclosed in Japanese Patent Application Laid-Open No. 11-223628, which detects the added reducing sugar by a color reaction, is basically a visual check for the presence or absence of coloration. Not suitable for automation. In addition, since the addition of reducing sugar is indispensable and the reaction reagent is also disposable, it is not a preferable method when applied to many specimens, and the management of the reaction reagent to be used, such as prevention of inactivation of the enzyme to be used. Attention should be paid to long-term storage.
The present invention has been made to solve these problems, and it is an object of the present invention to provide a method for simply detecting the activity of cement present in various specimens.
[0004]
[Means for Solving the Problems]
As a result of intensive studies in view of the above circumstances, the applicant has found that the activity of the cement has a correlation with the fluctuation pattern of the current value flowing between the electrodes made of a specific metal material, and has completed the present invention. . That is, the present invention is a method for detecting the activity of cement existing in cement milk, mortar, ready-mixed concrete, water containing at least cement, etc., and uses at least a pair of detection electrodes comprising an anode and a cathode. , the detection electrode is at least an anode, using the generated easily passive metal oxide film to the electrode surface to measure the current value flowing when a voltage is applied between the detection electrode, immediately after the voltage application This is a method for detecting the activity of cement, in which the activity of cement is judged based on the fluctuation pattern of the current value resulting from the formation of an oxide film on the electrode surface .
Although there are still unclear points regarding the detection of the activity of the cement according to the present invention, when aluminum or the like is used for the anode and a voltage is applied in an alkaline solution such as sodium hydroxide or calcium hydroxide, the electrode surface is immediately oxidized. It can be confirmed that there is a rapid decrease in current value (referred to as a passivation phenomenon) that is considered to be caused by film formation. (A metal such as aluminum used at this time is referred to as a passivating metal.) With respect to a sample containing cement that is the same alkaline solution, the phenomenon of the decrease in the current value is observed for the sample in which the cement hydration reaction is completed. As a method for detecting the activity of cement, it was found that only a sample with activity where the hydration reaction of cement was not completed was found, and that there was no decrease in current value due to some factor. It was developed.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The basic structure of the cement activity detection apparatus according to the present invention includes a detection electrode composed of an anode and a cathode, a power supply means for voltage application, a current value monitor, and the like.
The detection electrode is not particularly limited as long as it can measure the fluctuation pattern of the current value, and the shape, size, and distance between the electrodes are not particularly limited, but the anode uses a passivated metal that easily forms an oxide film. In particular, a metal material containing aluminum is preferable for the anode from the viewpoint of availability and processing. The cathode can be the same material as the anode or a different material.
Next, the polarity of the anode is inverted as a cleaning means for restoring the electrode function of the anode among the detection electrodes, so that the anode can be temporarily converted into the cathode. At this time, the polarity of the anode and the cathode constituting the detection electrode may be interchanged, and an auxiliary electrode is arranged in addition to the detection electrode, and the auxiliary electrode serves as the anode and both electrodes constituting the detection electrode serve as a voltage. Can also be applied.
The voltage applied by the power supply means for voltage application is preferably a constant voltage, and is preferably a direct current. The voltage value to be applied may be determined within a range in which a fluctuation pattern of the current value can be confirmed based on the size, shape, and material of the detection electrode, and also the concentration and properties of the specimen, and is usually 1V to 100V. Use ranges.
The current value fluctuation pattern may be a current value fluctuation pattern within 2 minutes immediately after application of the normal voltage.
[0006]
The activity range of the present invention indicates the following reaction state among cement solidification reactions. That is, there is a part where the hardening reaction of cement has not been elucidated, but first, when the cement comes into contact with water, the surface of 3CaO · Al ₂ O ₃ of one composition is finely formed by gypsum (Ca ₂ SO ₄ · 2H ₂ O). A dense film is made of ettringite crystals, and the hydration reaction rate of 3CaO.Al ₂ O ₃ is temporarily suppressed, while hydration reaction of 3CaO.SiO ₂ is similar to 3CaO.Al ₂ O _3. However, a thin hydrate film is formed on the surface, and the state in which the hydration reaction is low continues for a while. In the case of ordinary Portland cement, such a state continues for 4 to 5 hours after coming into contact with water, and then the most active hydration reaction of 3CaO.SiO ₂ occurs over a period of several tens of hours, resulting in formation of cement particle gaps. Solidification proceeds while being densely filled with gel (calcium-silicate-hydrate) or the like. It covers the state from the contact with water until the most active hydration reaction subsides.
In the method for detecting the activity of the cement according to the present invention, for example, when a detection electrode composed of aluminum as the anode and iron as the cathode is used, and a voltage is applied between the electrodes, the current value depends on the activity of the cement. For example, the variation pattern of FIG. 1 is in a form represented by FIG. 1- (A), FIG. 1- (B), and FIG. The fluctuation pattern of the current value when the activity of the cement remains sufficiently, the current value is almost constant as shown in FIG. 1- (B) or shows an increasing tendency as shown in FIG. 1- (A). On the other hand, the fluctuation pattern of the current value in the case where the activity is decreasing shows a rapid decreasing tendency immediately after voltage application as shown in FIG. Therefore, it is easy for the cement activity to remain simply by confirming that the current value variation pattern shown in FIGS. 1- (A) and 1- (B) is obtained when the electrode is inserted into the specimen. I understand.
[0007]
In carrying out the present invention, a portable measuring instrument can be used. For example, as shown in FIG. 2, a power source means 1 having an ammeter 2 and a recorder 3 has a positive electrode 5 and a negative electrode 6 for detection. Connect the electrode 4. In use, the cement activity can be easily confirmed simply by inserting the detection electrode 4 into the specimen. It is also possible to install a detection electrode on site and monitor it with a monitor such as a management room. Furthermore, by using a means to store and calculate the current value fluctuation pattern, the current value changes within a certain time. The amount can be converted into a numerical value, and the activity can be automatically determined based on this numerical value and displayed by turning on the lamp or recorded as an electric signal or reflected in various controls. For example, in the method (Japanese Patent Application No. 2001-396676) of electrolytically treating and dewatering sludge water containing cement developed by the present inventors, it can be used as a means for controlling the electrolytic treatment.
[0008]
【Example】
Hereinafter, the present invention will be described by way of examples.
(Example 1) An aluminum plate (thickness 1 mm, vertical and horizontal 10 mm) was used for the anode and the cathode, and an electrode for detecting the activity of cement with an electrode interval of 10 mm was prepared. A measuring instrument in which a power supply means for applying a constant voltage of 19 V and an ammeter were connected between the electrodes was prepared and used for the test.
3 parts by weight of sand, 3 parts by weight of gravel (maximum dimension 20mm), 0.5 parts by weight of water, 0.015 parts by weight of chemical admixture for concrete (AE water reducing agent, trade name "Pozoris 78S") per 1 part by weight of ordinary Portland cement Then, the detection electrode was inserted into the prepared ready-mixed concrete and allowed to stand at a room temperature of about 20 ° C. Fig. 6 shows the measurement results of current values when voltage is applied for 1 minute each at 5th, 10th, 20th, and 30th hours after preparing ready-mixed concrete for the inserted detection electrode. 3 shows. As shown in the figure, the fluctuation pattern of the current value at the 5th hour and the 10th hour became an upward trend and constant, respectively, but the fluctuation pattern of the current value at the 20th hour and the 30th hour showed a downward tendency. . Separately from the above test, about 100 g of ready-mixed concrete samples at each hour were collected, and the samples at the 5th and 10th hours were directly, and the samples at the 20th and 30th hours when solidification started. After pulverizing gravel with a hammer, the sample was suspended in 2 L of acetone, collected by suction filtration, and then dried to a constant temperature at 105 ° C. When measured according to the chemical analysis method of Portland cement (JIS R 5202), the loss on ignition of the samples at 5 hours and 10 hours was 2.1% and 3.6%, respectively, while the fluctuation of the current value was The ignition loss of the 20th and 30th hour samples whose patterns showed a decreasing tendency was 8.8% and 10.2%, respectively, and the amount of bound water was large and the hydration reaction was proceeding considerably. It was found.
In addition, although the case of ready-mixed concrete was demonstrated in this test example, it can measure similarly about cement milk, mortar, etc.
By using the method for detecting cement activity of the present invention, the cement activity existing in cement milk, mortar, ready-mixed concrete and the like can be easily detected, which is effective for cement evaluation tests. It can also be used as a technology related to the prevention of cold joints in concrete, which is a social problem.
[0009]
(Example 2) The activity of a cement composed of an aluminum plate having a thickness of 3 mm (immersion area: 80 × 50 mm) as the anode and an iron plate having a thickness of 3 mm (immersion area: 80 × 50 mm) as the cathode and having an electrode distance of 6 cm between the anode and the cathode. A power supply means for applying a constant voltage of 60 V and an ammeter were connected between the electrodes and used for the test.
Samples are 3 parts by weight of sand, 1 part by weight of normal Portland cement, 3 parts by weight of gravel (maximum dimension 20 mm), 0.5 parts by weight of water, 0.0115 parts by weight of chemical admixture for concrete (AE water reducing agent, trade name “Pozoris 78S”) The ready-mixed concrete was prepared, and sludge water containing cement prepared by adding approximately 5 times the weight of water to the ready-mixed concrete that had passed 3 hours after the adjustment was used as a specimen. The specimen was stirred with a stirrer, and the 1kg address was taken in a L160 × W120 × H120mm water tank made of an acrylic plate and used for the test.
FIG. 4 is a graph showing a fluctuation pattern of the current value for 2 minutes after the voltage is applied to those that have passed 1 hour, 5 hours, 15 hours, and 25 hours since the sludge water was created. As can be seen from FIG. 4, the current value of sludge water after 1 hour and 5 hours from the production showed an increasing tendency, whereas the sludge water after 15 hours and 25 hours had a decrease in current value. In addition to collecting the solid content from the sludge water of each elapsed time by suction filtration separately from the above test, and confirming the uniaxial compressive strength after 1 week, about what passed 1 hour and 5 hours from the sludge water preparation, 17.6 N / mm ² and 15.8 N / mm ² , indicating that the solidification activity remained sufficiently. On the other hand, connexion sludge water after 15 hours and 25 hours, respectively 6.7 N / mm ^2, is solidified activity at 5.8N / mm ² was found to have decreased.
In this test example, the case of sludge water generated from ready-mixed concrete was described, but the same measurement was also performed for water containing at least cement, that is, water intentionally added to waste water mixed with heavy metals. it can.
[0010]
(Example 3) Sludge water collected from a sludge water tank of a ready-mixed concrete manufacturing plant using the cement activity detection electrode shown in Example 2 (solid content concentration of about 6%, elapsed time after generation of sludge water is unknown ) And the results of attempts to detect the activity of sludge water (solid content concentration of about 5%) collected from the mixer car washing process in the same factory are shown in FIG. As shown in FIG. 5, the fluctuation pattern of the current value of the sludge water collected from the sludge water tank showed a decreasing tendency, and the fluctuation pattern of the current value showed an increasing tendency of those collected from the mixer car washing process. In addition to the above tests, solid content was collected by suction filtration for sludge water collected from the sludge water tank and mixer car washing process, and the uniaxial compressive strength after one week was confirmed. About sludge water collected from the sludge water tank, whereas showed low as 5.1 N / mm ^2, for sludge water mixer truck wash process, it was found that sufficient solidification activity becomes high value of 14.2N / mm ² was left .
By using the cement activity detection method of the present invention, sludge water containing cement discharged from the ready-mixed concrete mixing facility and the remaining ready-mixed concrete treatment process is dehydrated to produce and recycle a high-strength cake. At this time, it becomes possible to grasp the cement activity in the sludge water as the presence / absence of the actual activity rather than the temporal judgment, and a high-strength cake can be stably obtained. Further, when the sludge water is reused as ready-mixed concrete mixing water, it is possible to automate the supply of a retarder or the like by outputting the presence or absence of the cement activity as an electric signal.
[0011]
(Example 4) Using the electrode for detecting the activity of the cement shown in Example 2, the activity for a measurement time of 1 minute with respect to the sludge water prepared in Example 2 (25 hours after the sludge water was created) The degree detection was performed 5 times in succession. At this time, the result when the polarity of the anode of the detection electrode is not reversed is shown in FIG. 6- (A), and the polarity is reversed for 1 minute each time after detecting the activity, and the anode is converted into the cathode and the cathode is switched as the anode FIG. 6- (B) shows the result when the above is performed. As in Example 2, sludge water that has been produced for 25 hours is determined to have low cement activity in both cases from the current value fluctuation pattern in this example, but when polarity reversal is not performed. Each time the number of measurements increases, the initial current value immediately after voltage application decreases, that is, the electrode function of the detection electrode decreases. On the other hand, when polarity inversion is performed, the electrode function of the detection electrode recovers. I understand that.
[0012]
(Embodiment 5) As shown in FIG. 7, an auxiliary electrode 10 made of an iron plate (immersion area: 80 × 50 mm) is provided so as to face the anode 8 constituting the electrode 7 for detecting the activity of cement. A cement activity detection electrode 7 having a cathode 9 and an auxiliary electrode 10 arranged on the right and left in the center was prepared. Using this detection electrode 7, the activity was detected 5 times continuously in the same manner as in Example 4 for a measurement time of 1 minute. At this time, FIG. 8 shows the result when polarity reversal is performed in which a voltage of 60 V is applied using the detection electrode anode 8 as the cathode and the auxiliary electrode 10 as the anode for 1 minute each after the detection of the activity. Similarly to Example 2, sludge water that has passed for 25 hours is always determined to have low cement activity from the fluctuation pattern of the current value in this example as well, and between the auxiliary electrode 10 and the anode 8 of the detection electrode. It can be seen that the electrode function of the anode constituting the detection electrode is restored by applying a voltage between them.
[0013]
【The invention's effect】
According to claim 1, not only can the activity of cement in various specimens be detected easily, but also it can be handled as an electric signal by measuring the current value, so that the ease of recording or the control of subsequent processes based on the results, etc. Automation becomes extremely easy.
According to the second aspect, by using a passivated metal that easily forms an oxide film on at least the anode among the detection electrodes, the fluctuation pattern of the current value when there is no cement activity becomes clearer.
According to the third aspect, since a material containing aluminum at least in the anode can be used, the electrode material can be easily obtained and processed.
According to the fourth and fifth aspects, since the electrode function of the detection electrode is restored only by voltage application, the detection electrode can be repeatedly used.
[Brief description of the drawings]
FIGS. 1A and 1B are graphs of fluctuation patterns of current values when cement activity remains sufficiently. C shows a graph of the fluctuation pattern of the current value when the activity of the cement is lowered.
FIG. 2 is a conceptual diagram showing an example of a measuring instrument that measures a current value.
FIG. 3 is a graph showing a fluctuation pattern of a current value in ready-mixed concrete with respect to an elapsed time after kneading.
FIG. 4 is a graph showing a fluctuation pattern of a current value in sludge water with respect to an elapsed time after creation.
FIG. 5 is a graph showing a fluctuation pattern of a current value due to a difference between detection bodies.
FIG. 6 is a graph showing a fluctuation pattern of a current value when the anode and the cathode of the detection electrode are switched.
FIG. 7 shows a conceptual diagram when an auxiliary electrode is used.
FIG. 8 is a graph showing a fluctuation pattern of a current value when polarity is inverted using an auxiliary electrode.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power supply means 2 Ammeter 3 Recorder 4,7 Detection electrode 5,8 Anode 6,9 Cathode 10 Auxiliary electrode

Claims

Cement milk, mortar, a ready-mixed concrete or at least cement laden activity detection method of the cement present in the water or the like, using at least a pair of detection electrodes consisting of an anode and a cathode, the said detection electrode , at least an anode, using a passivating metal to the electrode surface tends to produce an oxide film, a current flowing when a voltage is applied between the detection electrode is measured, oxide film of the electrode surface just after the voltage application A method for detecting the activity of cement, comprising determining the activity of cement based on a fluctuation pattern of a current value caused by generation .

The cement activity detection method according to claim 1, wherein when the current value fluctuation pattern shows a rapid decrease tendency, the cement activity is determined to be decreasing .

The detection electrode, activity detection method of the cement according to claim 1 or 2, characterized in that a metal containing aluminum at least in the anode.

The activity detection of cement according to any one of claims 1 to 3, wherein the detection electrode performs polarity reversal using an anode as a cathode in order to restore the function of the electrode. Method.

The detection electrode includes an auxiliary electrode other than the detection electrode to restore the function of the electrode, and performs polarity reversal using the auxiliary electrode as an anode and the detection electrode as a cathode. Item 4. Cement activity detection method according to item 4