JP4021674B2 - Manufacturing method and construction method of cement mixture - Google Patents
Manufacturing method and construction method of cement mixture Download PDFInfo
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- JP4021674B2 JP4021674B2 JP2002023665A JP2002023665A JP4021674B2 JP 4021674 B2 JP4021674 B2 JP 4021674B2 JP 2002023665 A JP2002023665 A JP 2002023665A JP 2002023665 A JP2002023665 A JP 2002023665A JP 4021674 B2 JP4021674 B2 JP 4021674B2
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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
- Y02W30/00—Technologies for solid waste management
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Description
【０００１】
【発明が属する技術分野】
本発明は粒鉄を含むセメント混合物の製造方法および施工方法に関する。
【０００２】
【従来の技術】
ケーソンなどの港湾構造物では、比較的大きな揚圧力が作用することがあり、この場合、揚圧力に対抗するために構造物の躯体内にコンクリートを打設し、これをウエイト材料とすることで構造物の重量を増加させて安定を図っている。
【０００３】
また揚圧力の問題は港湾構造物のみならず、市街地における構造物には生じている。すなわち、近年の市街地においては地下水位が上昇する傾向が認められ、この地下水位の上昇に伴なって地下構造物には大きな揚圧力が作用し、特に、地震時においては地下構造物が浮上する可能性も指摘されており、ここでも、ウエイト材料の必要性が高まっている。
【０００４】
【発明が解決しようとする課題】
上記のような問題に対し、コンクリートをウエイト材料として使用することが提案されているが、通常のコンクリートの比重は約２．３５ｔ／ｍ3程度であり、充分な重量を得ようとするとウエイト材料の容量が大きくなるため、構造物自体の容量も大きくなり、全体の材料及び施工コストも上昇するという欠点がある。
【０００５】
またウエイト材料として従来の遮蔽用コンクリートなどの重量コンクリートを使用することも考えられるものの、重量コンクリートをコンクリート製造プラントで練り混ぜると、設備コストが高くなる。また一バッチ当たりの練混ぜ量も少なく、ミキサーの摩耗も激しいことからランニングコストも高くなるという欠点がある。
【０００６】
本発明は上記のような問題点を解決するためになされたものであり、その課題は、比重が約２．３５ｔ／ｍ3程度の従来のコンクリートに比べると比重が大きく、したがって、構造物自体の容量を小さくしても、揚圧力に対して充分に対抗可能なウエイト材料、すなわち、セメント混合物を製造する方法を提供することにある。
【０００７】
本発明の別の課題は、セメント混合物を混合するための装置の摩耗による損失を抑制し、セメント混合物製造のための設備コスト、ランニングコストを抑制できるセメント混合物の製造方法を提供することにある。
【０００８】
また本発明の別の課題は、比重が約２．３５ｔ／ｍ3程度の従来のコンクリートに比べると比重が大きいセメント混合物を比較的容易に打設することができて、しかも、所要の圧縮強度を確実に得ることができる、セメント混合物を用いた施工法を提供することにある。
【００１０】
【課題を解決するための手段】
本発明によれば、作業ヤードにコンクリートスラブを形成し、該コンクリートスラブ上の所定面積を囲むように、所定長にわたる所定高さの壁体を形成し、該コンクリートスラブと該壁体とで囲まれた内部を、粒鉄の容量を計測するための計測枡として使用し、該計測後に計測枡内に所定量の砂および所定量のセメントを加えて攪拌し、さらに、スランプが０になる程度の水を計測枡内に加えて攪拌することを特徴とするセメント混合物の製造方法が提供される。
【００１１】
さらに、本発明によれば、上記のように製造されたセメント混合物を搬送車両の荷台に積載して打設現場に搬送し、該打設現場でセメント混合物を荷台から降ろしてほぼ平らに敷均し、この後にセメント混合物を振動ローラーで転圧して締め固めることを特徴とするセメント混合物を用いた施工方法が提供される。
【００１２】
【発明の実施の形態】
前記粒鉄とは、鉄鋼製造における副産物であり、高炉で作られる銑鉄から燐、硫黄、炭素を取り除く精錬工程で生成される溶銑予備処理スラグ、転炉スラグ等の製鋼スラグを破砕する際に磁選回収される鉄分であり、本発明においては、特に密度が５ｇ／ｃｍ3以上の粒鉄を使用することが好ましい。
【００１３】
前記粒鉄は、蒸気エージングを実施して水膨張率を０．１％以下にしたものを使用することが好ましい。上述の如く、粒鉄は、破砕した製鋼スラグから磁選回収された鉄分であるため、製鋼スラグを含有することがある。製鋼スラグは不安定な鉱物相からできているため、セメントと混合して硬化体を作ったときには遊離石灰の水和反応による膨張が問題になる。したがって、粒鉄に製鋼スラグが含まれるか否かにかかわらず、あらかじめ粒鉄に蒸気エージングを実施しておくことが好ましく、これにより、粒鉄に製鋼スラグが含まれている場合にも、膨張率は０．１％以下に抑えることが可能になる。
【００１４】
前記セメント混合物の製造方法において、計測枡を構成する壁体の内面には粒鉄の容量を規定する目印の線をあらかじめ引いておくことが好ましく、これにより、この線を目安に計測枡内に粒鉄を入れるだけで粒鉄の容量を容易に計測することができる。
また計測枡を構成する壁体の内面には、粒鉄の容量を規定する目印線に加えて、この目印線の上に砂の容量を規定する目印の線を設けても良い。この場合、最初に、粒鉄を計測枡内の目印線まで入れて表面を均し、この粒鉄の上から砂を入れて目印の線にあわせれば、砂の計量も容易に計測することができる。
【００１５】
前記計測枡内において粒鉄、砂、セメントを攪拌する手段、また前記計測枡内に更に水を加えて攪拌する手段としては、下記のような装置を用いることができる。すなわち、履体付車輪を含む自走手段と、伸縮シリンダーにより角度可変に形成されて該自走手段上に設けられたアームと、該アームの先端に角度可変に枢着されたバケットとを含む装置を、攪拌手段として用いることができる。このような攪拌装置としては、例えば、バックホウ、スケルトン付バックホウ又はツインヘッダ等がある。
上述のような計測枡で粒鉄や砂を計測し、この計測枡内で前記攪拌装置によりセメントと水等を混合すれば、従来の二軸強制練りミキサーなどの装置による練混ぜ工程に較べて、設備コストやランニングコストを低減することができる。
【００１６】
【実施例】
以下、本発明の好適な実施例を説明するが、本発明はこれらに限定されるものではない。
【００１７】
＜粒径の水浸膨張比試験＞
粒径がほぼ５〜７０ｍｍの範囲内に収まるように粒鉄をふるい分けし、これに２４時間の蒸気エージングを実施して促進養生した。蒸気エージング前後の粒鉄に対し、ＪＩＳＡ５０１５付属書２に規定された水浸膨張比試験を行い、その結果を図１に示した。
水浸膨張比試験の結果、蒸気エージングを実施しない粒鉄では、水浸膨張比が０．４％を越えて上昇したのに対し、２４時間の蒸気エージングを実施した粒鉄では、水浸膨張比が０．１％以下に抑制されていた。
【００１８】
＜セメント混合物の室内試験練り＞
蒸気エージングを実施した粒鉄を使用して室内試験練りを実施した。試験練りは、単位セメント量１００ｋｇ／ｍ3、水セメント比１１０％の貧配合のものと、単位セメント量１９２ｋｇ／ｍ3、水セメント比６５％の富配合のものについて実施した。また両配合についてフライアッシュを混入したものとしないものとを実施し、それぞれについてＶＣ値が２０秒程度となる配合を定めて、ＪＩＳＡ１０００に規定された供試体を作成した。これらの供試体について圧縮強度試験と、粒鉄の膨張による破壊の確認試験とを実施し、その結果を表１に示した。
【表１】
なお、比較例として、蒸気エージング前の粒鉄を使用し、フライアッシュを混入しない富配合のものと同じ配合で供試体を作成したが、これには、ひび割れの発生が認められた。
【００１９】
＜試験施工のための示方配合＞
以上の室内試験練り結果から、セメント混合物の配合を表２のように定めた。
【表２】
また単位水量は、セメント混合物のスランプが０で、かつＶＣ値が２０秒程度に定め、超硬練状態になるようにした。このように単位水量を定めた場合、セメントの使用量に対して水の使用量が少ないため、単位セメント量を少なくすることができて、少ない単位セメント量の割には、大きな圧縮強度を得ることができる。また、このような超硬練状態にすることで、単位粗骨材量、すなわち粒鉄の単位量を大きくすることができるので、セメント混合物自体の単位容積重量も大きくできるという利点がある。さらに、超硬練状態にすることで、セメント混合物を構成する材料の材料分離を防止することが可能になり、汎用機械であるダンプトラックやブルドーザー、振動ローラーでの施工が可能になった。
なお、ＶＣ値とは標準ＶＣ試験から得られる値であり、この標準ＶＣ試験は、硬練りコンクリートのコンシステンシーを評価する方法の一つとして採用されているものである。すなわち、標準ＶＣ試験とは、硬練りコンクリートをモールドに詰め込み、このモールドに約５０Ｈｚ、振幅１ｍｍ程度の振動を与え、モルタルが表面に浮き上がるまでの時間を測定するものであり、この時間をＶＣ値とするものである。一般的なＲＣＤコンクリートにおいて、ＶＣ値は２０±１０秒程度である。
【００２０】
＜計測枡の形成＞
計測枡について以下に説明する。
捨てコンクリートを作業ヤードに打設してスラブ版を形成し、このスラブ版の上に、長方形の三辺を描くように所定高さの連続壁を形成し、これらのスラブ版と連続壁とで囲まれた内部を、粒鉄や細骨材の容量を計測するとともに、これらの材料とセメント等の材料を混合するための計測枡とする。連続壁の内面には、粒鉄の容量を規定する線と、細骨材の容量を規定する線とを引く。これらの線は、例えば、粒鉄を計測枡に入れて平らに均したときに、その表面が線とほぼ同じ高さになるように目印にする線であり、粒鉄のための線の上方に、細骨材のための線を設けるか、あるいは逆に設けても良い。
なお、密度が判っている細骨材を使用し、重量があらかじめ計測されている場合には、計測枡に細骨材の容量を規定する線を設ける必要はない。
本実施例では、縦×横＝１０ｍ×１０ｍの長方形のうち、一辺を除いた三辺に沿って高さ０．７ｍで厚さ２０ｃｍの連続壁をスラブ版の上に形成し、これらのスラブ版と連続壁とで囲まれた約７０ｍ3を計測枡とし、この計測枡内で５０ｍ3程度のセメント混合物を製造した。
【００２１】
＜セメント混合物の製造方法＞
次に、上記した配合でセメント混合物を製造する方法について説明する。
最初に、粒鉄をストックヤードから作業ヤードまで搬送し、上記計測枡内に入れて敷き均し、その表面が連続壁の目印線とほぼ同じ高さになったら、粒鉄の投入を停止する。次に、粒鉄のうえから細骨材を入れて敷き均し、同様に、目印線に達したら細骨材の投入を停止し、この上から所定量のセメントを散布してほぼ均等になるようにバックホウにて攪拌する。粒鉄、細骨材、セメントが充分に練り混ぜられたら、必要量の水を散水してバックホウで再度練混ぜると、セメント混合物が生成される。
最後に、粒鉄、細骨材、セメントが均等に練り混ぜられたことを確認するために、セメント混合物の複数の箇所でフェノールフタレイン溶液を霧吹きで吹き付ける。セメント混合物が均等に赤紫色に変色すれば、セメントが均等に分散していることが判る。
粒鉄を含むセメント混合物をバッチャープランントのミキサーで練混ぜると、粒鉄の衝突でミキサーが摩耗し、設備のメンテナンスコストが大きくなるという欠点がある。またウエイト材料としてセメント混合物を用いるような場合には、厳格な品質管理が要求されない。したがって、上記のような計測枡による計量および練混ぜにより、セメント混合物を製造すれば、設備コストを低く抑えながら、しかも、充分な品質のセメント混合物を製造することができる。
【００２２】
＜セメント混合物の施工方法＞
次に、上述の如く製造されたセメント混合物を施工する方法について説明する。
製造されたセメント混合物をバックホウによりダンプトラックの荷台に積み込んで打設現場まで搬送し、打設現場でダンプトラックの荷台を傾けてセメント混合物を降ろし、このセメント混合物をブルドーザーでほぼ平らに敷き均し、この後にセメント混合物を振動ローラーで転圧して締め固めれば、セメント混合物の施工が完了する。
【００２３】
＜試験施工条件＞
本実施例の試験施工では、上記計量枡でセメント混合物を製造し、このセメント混合物を０．７ｍ3のバックホウで１０トンのダンプトラックの荷台に積み込み、１５トン級のブルドーザーでダンプトラック１台分のセメント混合物を１リフト（１層）３０ｃｍの厚さに敷き均し、この後に、１０トン級の振動ローラーを使用して１２回転圧して締め固め、以上のセメント混合物製造から転圧までの工程を三回繰り返して３リフト（３層）からなるセメント硬化体を作成した。
試験施工当日の天候は、晴れ後一時薄曇りで日中平均気温は２５．６度、最高気温は３０．６度であった。
【００２４】
＜試験施工の所要時間＞
粒鉄、細骨材、セメントが練り混ぜられものに加水を開始したのち、練混ぜ、敷き均し及び転圧が終了するまでの時間を各リフト毎に計測したが、その平均時間は１５１分であった。
【００２５】
＜試験施工におけるＶＣ値＞
各リフトを構成するセメント混合物について、練り混ぜ直後に、標準ＶＣ試験を実施したところ、全採取試料のＶＣ値の平均は１８．２秒、変動係数は８８．９％であった。またＶＣ値の経時変化を求めたところ、練り混ぜ直後に５秒程度であったＶＣ値が約２時間後に２０秒程度、約４時間後に６０秒程度になった。本発明によるセメント混合物のＶＣ値の経時変化は、通常のＲＣＤ用コンクリートと比較して特に劣るものではなく、練り混ぜ直後のＶＣ値がほぼ２０秒以下であれば、たとえ、練り混ぜ後から転圧開始までの間に２時間程度が経過しても、締め固め作業は充分に実施可能である。
【００２６】
＜試験施工における沈下量＞
各リフト毎に振動ローラーの転圧による沈下量を測定し、この結果を図２に示した。図２において沈下率とは、各リフト厚さ３０ｃｍに対する沈下量の比率を表したものである。各リフトの平均沈下量は２〜４ｃｍ程度であり、沈下率は約１０％であった。４回の転圧で、沈下量のほとんどが発現しているものの、１２回の転圧までは沈下率が上昇傾向を示している。従来のＲＣＤ工法の実績では、リフト厚さ５０ｃｍの場合には転圧回数は６回と規定された例がほとんどであり、本発明によるセメント混合物も、従来のＲＣＤ用コンクリートと同様な締め固め易さを有することが判る。
【００２７】
＜セメント硬化体の圧縮強度＞
各リフト毎に採取した試料について直径１００ｍｍ、高さ２００ｍｍの円柱供試体を作成し、ＪＩＳＡ１０００に規定された圧縮強度試験を実施した。材齢２８日の全供試体の平均値は２１．７Ｎ／ｍｍ2、変動係数は２１．７％であった。従来のＲＣＤ工法の実績では、ＲＣＤ用コンクリートの設計強度が７〜１５Ｎ／ｍｍ2程度に定められたものが多く、本発明によるセメント混合物の圧縮強度は、これと比較しても、特に劣るものではない。
【００２８】
＜セメント硬化体の単位容積重量＞
各リフトから採取した圧縮強度試験のための供試体ごとに単位容積重量を計測した。全供試体の平均値は約３．２９ｔ／ｍ3、変動係数は１．２％であった。従来のコンクリート、すなわち、天然の骨材を用いたコンクリートは、単位容積重量が約２．３５ｔ／ｍ3程度であるが、これと比較すると、本発明によるセメント混合物はウエイト材料として充分な単位容積重量を備えることがわかる。
【００２９】
【発明の効果】
本発明のセメント混合物は、鉄鋼製造工程で製鋼スラグから磁選回収された鉄分である粒鉄を含むため、約２．３５ｔ／ｍ3程度の従来のコンクリートに比べて、混合物自体の単位容積重量が格段に大きなものになり、したがって、このセメント混合物をウエイト材料として使用した場合には、たとえ、構造物自体の容量を小さくしても、揚圧力に対して充分に対抗することが可能になる。したがって、揚圧力に対抗可能な構造物を構築する際の施工コストを抑制することができて、必要とする用地も小さくすることができる。
【００３０】
本発明のセメント混合物は粒鉄を含み、この粒鉄は鉄鋼製造工程で製鋼スラグから磁選回収された副産物であるため、粒鉄の有効利用、ひいては資源の有効活用が可能になる。
【００３１】
本発明のセメント混合物の製造方法では、作業ヤードに形成した計測枡によって粒鉄や砂の容量を計測し、この計測枡内で材料を攪拌するので、攪拌にはバックホウなどの装置を使用することができる。したがって、ミキサー等を備えたコンクリート製造プラントは不要であり、セメント混合物製造のための設備コスト、ランニングコストを安価にすることが可能になる。
【００３２】
本発明のセメント混合物を用いた施工方法では、搬送車両の荷台に積載して打設現場に搬送し、打設現場でセメント混合物を荷台から降ろしてほぼ平らに敷均し、この後にセメント混合物を振動ローラーで転圧して締め固めるものであるため、これらの工程は、緩やかな施工管理で実施できるため手間がかからず、しかも、汎用機械であるダンプトラックやブルドーザー、振動ローラーで施工することができて施工コストを低廉に抑えることが可能になった。
【図面の簡単な説明】
【図１】蒸気エージング前後の粒鉄に対して行った水浸膨張比試験の結果を示したグラフである。
【図２】試験施工において振動ローラーの転圧による沈下量を測定し、この結果を示したグラフである。[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for producing a cement mixture containing granular iron and a construction method.
[0002]
[Prior art]
In harbor structures such as caisson, a relatively large lifting pressure may act. In this case, concrete is placed in the frame of the structure to counter the lifting pressure, and this is used as a weight material. The weight of the structure is increased to ensure stability.
[0003]
Moreover, the problem of lift pressure is occurring not only in port structures but also in urban structures. In other words, in recent urban areas, there is a tendency for the groundwater level to rise, and as the groundwater level rises, a large lifting pressure acts on the underground structure, and the underground structure rises especially during an earthquake. The possibility is also pointed out, and here again the need for weight materials is increasing.
[0004]
[Problems to be solved by the invention]
In order to solve the above problems, it has been proposed to use concrete as a weight material, but the specific gravity of ordinary concrete is about 2.35 t / m 3 , and weight material is used to obtain a sufficient weight. Since the capacity of the structure increases, the capacity of the structure itself increases, and the overall material and construction cost also increase.
[0005]
Although it is conceivable to use conventional heavy concrete such as shielding concrete as the weight material, if the heavy concrete is mixed in a concrete production plant, the equipment cost increases. In addition, the amount of kneading per batch is small, and the mixer is heavily worn.
[0006]
The present invention has been made to solve the above problems, and the problem is that the specific gravity is larger than that of conventional concrete having a specific gravity of about 2.35 t / m 3 , and thus the structure itself. It is an object of the present invention to provide a method for producing a weight material, that is, a cement mixture which can sufficiently resist the lifting pressure even if the capacity of the cement is reduced.
[0007]
Another subject of this invention is providing the manufacturing method of the cement mixture which can suppress the loss by the abrasion of the apparatus for mixing a cement mixture, and can suppress the installation cost for a cement mixture manufacture, and a running cost.
[0008]
Another object of the present invention is that a cement mixture having a higher specific gravity than that of conventional concrete having a specific gravity of about 2.35 t / m 3 can be placed relatively easily, and the required compressive strength is achieved. It is in providing the construction method using the cement mixture which can obtain reliably.
[0010]
[Means for Solving the Problems]
According to the present invention , a concrete slab is formed in a work yard, a wall body having a predetermined height over a predetermined length is formed so as to surround a predetermined area on the concrete slab, and the wall is surrounded by the concrete slab and the wall body. The inside is used as a measuring rod for measuring the capacity of the granular iron. After the measurement, a predetermined amount of sand and a predetermined amount of cement are added and stirred in the measuring rod, and the slump is zero. A method for producing a cement mixture is provided, wherein the water is added to a measuring vessel and stirred.
[0011]
Further, according to the present invention, the cement mixture manufactured as described above is loaded on the loading platform of the transport vehicle and transported to the placing site, and the cement mixture is lowered from the loading platform at the placing site and spread almost flatly. Then, a construction method using the cement mixture is provided, in which the cement mixture is compacted by compaction with a vibrating roller.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The granular iron is a by-product in steel production, and magnetic separation is used when crushing steelmaking slag such as hot metal pretreatment slag and converter slag produced in a refining process that removes phosphorus, sulfur and carbon from pig iron produced in a blast furnace. In the present invention, it is preferable to use granular iron having a density of 5 g / cm 3 or more.
[0013]
It is preferable to use the granular iron that has been subjected to steam aging and has a water expansion coefficient of 0.1% or less. As described above, the granular iron is an iron component magnetically collected from the crushed steelmaking slag, and thus may contain steelmaking slag. Since steelmaking slag is made of an unstable mineral phase, when it is mixed with cement to make a hardened body, expansion due to hydration of free lime becomes a problem. Therefore, regardless of whether or not steel slag is included in the granular iron, it is preferable to perform steam aging in advance in the granular iron, and thereby, even when the steel slag is included in the granular iron, expansion The rate can be suppressed to 0.1% or less.
[0014]
In the method for producing a cement mixture, it is preferable to draw in advance a mark line that defines the capacity of the granular iron on the inner surface of the wall constituting the measurement rod. It is possible to easily measure the capacity of granular iron simply by adding granular iron.
In addition to the mark line that defines the capacity of the granular iron, a mark line that defines the capacity of the sand may be provided on the inner surface of the wall constituting the measuring rod. In this case, first, put the grain iron up to the mark line in the measuring bowl, level the surface, put sand from above the grain iron and match it with the mark line, you can easily measure the sand measurement. it can.
[0015]
The following devices can be used as means for stirring the granular iron, sand, and cement in the measuring bowl, and means for adding water and stirring the measuring bowl. That is, it includes a self-propelled means including a wheel with a footwear, an arm formed on the self-propelled means with a variable angle by an extension cylinder, and a bucket pivotally attached to the tip of the arm. The apparatus can be used as a stirring means. Examples of such a stirring device include a backhoe, a backhoe with a skeleton, a twin header, and the like.
If granular iron and sand are measured with the measuring rod as described above, and cement and water are mixed with the stirring device in the measuring rod, compared with the mixing process by a device such as a conventional biaxial forced mixing mixer. Equipment costs and running costs can be reduced.
[0016]
【Example】
Hereinafter, preferred examples of the present invention will be described, but the present invention is not limited thereto.
[0017]
<Water immersion expansion ratio test of particle size>
Grained iron was screened so that the particle size would fall within the range of approximately 5 to 70 mm, and steam aging was performed for 24 hours to promote curing. The granular iron before and after steam aging was subjected to the water immersion expansion ratio test specified in
As a result of the water immersion expansion ratio test, in the case of granular iron not subjected to steam aging, the water immersion expansion ratio increased by more than 0.4%, whereas in the case of granular iron subjected to 24 hours of steam aging, the water immersion expansion The ratio was suppressed to 0.1% or less.
[0018]
<In-house testing of cement mixture>
Laboratory test kneading was performed using granular iron subjected to steam aging. The test kneading was carried out for a poor blend with a unit cement amount of 100 kg / m 3 and a water cement ratio of 110% and a rich blend with a unit cement amount of 192 kg / m 3 and a water cement ratio of 65%. Moreover, what mixed the fly ash with and without the fly ash for both the blends was determined, and blends with a VC value of about 20 seconds were determined for each, and specimens defined in JIS A1000 were prepared. These specimens were subjected to a compressive strength test and a fracture confirmation test due to the expansion of granular iron, and the results are shown in Table 1.
[Table 1]
As a comparative example, a specimen was prepared with the same composition as that of the rich composition not containing fly ash, using granular iron before steam aging, but cracking was observed.
[0019]
<Indication mix for test construction>
From the above-mentioned laboratory test kneading results, the composition of the cement mixture was determined as shown in Table 2.
[Table 2]
In addition, the unit water amount was set such that the slump of the cement mixture was 0 and the VC value was about 20 seconds, so that a super kneaded state was obtained. When the unit water amount is determined in this way, the amount of water used is less than the amount of cement used, so the unit cement amount can be reduced, and a large compressive strength is obtained for the smaller unit cement amount. be able to. In addition, since the amount of unit coarse aggregate, that is, the unit amount of granular iron can be increased by using such a super-kneaded state, there is an advantage that the unit volume weight of the cement mixture itself can be increased. Furthermore, the super-kneaded state can prevent the material constituting the cement mixture from being separated, and construction with a general-purpose machine such as a dump truck, a bulldozer, or a vibrating roller is possible.
The VC value is a value obtained from a standard VC test, and this standard VC test is adopted as one method for evaluating the consistency of kneaded concrete. That is, the standard VC test is a method in which hard concrete is packed in a mold, vibration is applied to the mold at about 50 Hz and an amplitude of about 1 mm, and the time until the mortar floats on the surface is measured. It is what. In general RCD concrete, the VC value is about 20 ± 10 seconds.
[0020]
<Formation of measuring rod>
The measuring rod will be described below.
Abandoned concrete is placed in the work yard to form a slab plate, and a continuous wall of a predetermined height is formed on this slab plate so as to draw three sides of the rectangle. The enclosed interior is used as a measuring rod for measuring the volume of granular iron and fine aggregate and mixing these materials with materials such as cement. On the inner surface of the continuous wall, a line defining the capacity of the granular iron and a line defining the capacity of the fine aggregate are drawn. These lines, for example, are the lines that mark the surface so that the surface is approximately the same height as the line when it is leveled in a measuring rod, above the line for the granular iron Alternatively, a line for fine aggregate may be provided, or vice versa.
In addition, when the fine aggregate whose density is known is used and the weight is measured in advance, it is not necessary to provide a line for defining the capacity of the fine aggregate on the measuring rod.
In this example, a continuous wall having a height of 0.7 m and a thickness of 20 cm is formed on the slab plate along three sides excluding one side of a rectangle of length × width = 10 m × 10 m. About 70 m 3 surrounded by the plate and the continuous wall was used as a measuring bowl, and a cement mixture of about 50 m 3 was produced in the measuring bowl.
[0021]
<Method for producing cement mixture>
Next, a method for producing a cement mixture with the above composition will be described.
First, transport the granular iron from the stock yard to the work yard, place it in the measuring jar, spread it, and when the surface is almost level with the mark line of the continuous wall, stop the injection of the granular iron. . Next, put fine aggregate on top of the grain iron and spread it out. Similarly, when the mark line is reached, the fine aggregate is stopped and a predetermined amount of cement is sprinkled over to make it almost even. Stir with a backhoe. When the granular iron, fine aggregate, and cement are sufficiently mixed, the required amount of water is sprinkled and mixed again with a backhoe to form a cement mixture.
Finally, in order to confirm that the granular iron, fine aggregate, and cement are kneaded evenly, the phenolphthalein solution is sprayed at a plurality of locations of the cement mixture. If the cement mixture turns uniformly reddish purple, it can be seen that the cement is evenly dispersed.
When a cement mixture containing granular iron is mixed with a batcher plant mixer, the mixer wears due to the collision of the granular iron, resulting in an increase in the maintenance cost of the equipment. In addition, when a cement mixture is used as the weight material, strict quality control is not required. Therefore, if a cement mixture is manufactured by measurement and kneading with the measuring rod as described above, a cement mixture with sufficient quality can be manufactured while keeping facility costs low.
[0022]
<Cement mixture construction method>
Next, a method for applying the cement mixture manufactured as described above will be described.
The manufactured cement mixture is loaded onto a dump truck bed by a backhoe and transported to the setting site, the dump truck bed is tilted at the setting site, the cement mixture is lowered, and this cement mixture is spread almost evenly with a bulldozer. Then, if the cement mixture is compacted by compaction with a vibrating roller, the construction of the cement mixture is completed.
[0023]
<Test construction conditions>
In the test construction of this example, a cement mixture was manufactured with the above-mentioned measuring rod, and this cement mixture was loaded on a 10-ton dump truck bed with a 0.7 m 3 backhoe, and a dump truck with a 15-ton class bulldozer. 1 cement (1 layer) 30cm thick, and after that, using a 10-ton class vibration roller, press and compact 12 times to make the above cement mixture production to rolling Was repeated three times to prepare a hardened cement body consisting of 3 lifts (3 layers).
The weather on the test day was slightly cloudy after clear weather, with an average daytime temperature of 25.6 ° C and a maximum temperature of 30.6 ° C.
[0024]
<Time required for test construction>
After starting to add water to a mixture of granular iron, fine aggregate and cement, the time until mixing, laying and leveling and rolling were completed was measured for each lift. The average time was 151 minutes. Met.
[0025]
<VC value in test construction>
A standard VC test was performed on the cement mixture constituting each lift immediately after kneading. As a result, the average VC value of all the collected samples was 18.2 seconds, and the coefficient of variation was 88.9%. Further, when the change with time of the VC value was determined, the VC value, which was about 5 seconds immediately after kneading, became about 20 seconds after about 2 hours and about 60 seconds after about 4 hours. The change over time of the VC value of the cement mixture according to the present invention is not particularly inferior to that of ordinary RCD concrete. If the VC value immediately after mixing is approximately 20 seconds or less, even if the VC value immediately after mixing is less than 20 seconds. Even if about 2 hours elapse before the pressure starts, the compacting operation can be sufficiently performed.
[0026]
<Subsidence amount in test construction>
The amount of settlement due to the rolling pressure of the vibrating roller was measured for each lift, and the results are shown in FIG. In FIG. 2, the settlement rate represents the ratio of the settlement amount to each lift thickness of 30 cm. The average subsidence amount of each lift was about 2 to 4 cm, and the subsidence rate was about 10%. Although most of the subsidence amount is expressed by four times of rolling pressure, the settlement rate shows an increasing tendency until twelve times of rolling pressure. According to the results of the conventional RCD method, in most cases, when the lift thickness is 50 cm, the number of times of rolling is defined as six times, and the cement mixture according to the present invention can be compacted as easily as conventional RCD concrete. It can be seen that
[0027]
<Compressive strength of hardened cement paste>
A cylindrical specimen having a diameter of 100 mm and a height of 200 mm was prepared for each sample collected for each lift, and a compressive strength test prescribed in JISA1000 was performed. The average value of all specimens at the age of 28 days was 21.7 N / mm 2 , and the coefficient of variation was 21.7%. In the past results of the RCD method, the design strength of concrete for RCD is often set to about 7 to 15 N / mm 2 , and the compressive strength of the cement mixture according to the present invention is particularly inferior to this. is not.
[0028]
<Unit volume weight of hardened cement body>
Unit volume weight was measured for each specimen for compressive strength test collected from each lift. The average value of all specimens was about 3.29 t / m 3 and the coefficient of variation was 1.2%. Conventional concrete, that is, concrete using natural aggregate has a unit volume weight of about 2.35 t / m 3 , but compared with this, the cement mixture according to the present invention has a sufficient unit volume as a weight material. You can see that it has weight.
[0029]
【The invention's effect】
Since the cement mixture of the present invention includes granular iron, which is iron that has been magnetically recovered from steelmaking slag in the steel production process, the unit volume weight of the mixture itself is smaller than that of conventional concrete of about 2.35 t / m 3. Therefore, when this cement mixture is used as a weight material, even if the capacity of the structure itself is reduced, it is possible to sufficiently resist the lifting pressure. Therefore, the construction cost when constructing a structure capable of resisting the lifting pressure can be suppressed, and the required site can be reduced.
[0030]
Since the cement mixture of the present invention contains granular iron, and this granular iron is a by-product that has been magnetically collected from steelmaking slag in the steel manufacturing process, it is possible to effectively use the granular iron, and hence the resource.
[0031]
In the method for producing a cement mixture according to the present invention, the volume of granular iron and sand is measured with a measuring rod formed in a work yard, and the material is stirred in the measuring rod. Therefore, a device such as a backhoe is used for stirring. Can do. Therefore, a concrete production plant equipped with a mixer or the like is not necessary, and the equipment cost and running cost for producing the cement mixture can be reduced.
[0032]
In the construction method using the cement mixture of the present invention, it is loaded onto the loading platform of the transport vehicle and transported to the placing site, and the cement mixture is lowered from the loading platform at the placing site and leveled almost flat, and then the cement mixture is placed. These processes are compacted by rolling with a vibrating roller, so these processes can be carried out with gradual construction management, so it is not time-consuming, and it can be performed with a general purpose machine such as a dump truck, bulldozer, or vibrating roller. As a result, construction costs can be kept low.
[Brief description of the drawings]
FIG. 1 is a graph showing the results of a water immersion expansion ratio test performed on granular iron before and after steam aging.
FIG. 2 is a graph showing the result of measuring the amount of settlement due to rolling of a vibrating roller in test construction.
Claims (3)
作業ヤードにコンクリートスラブを形成し、該コンクリートスラブ上の所定面積を囲むように、所定長にわたる所定高さの壁体を形成し、該コンクリートスラブと該壁体とで囲まれた内部を、粒鉄の容量を計測するための計測枡として使用し、該計測後に計測枡内に所定量の砂および所定量のセメントを加えて攪拌し、さらに、スランプが０になる程度の水を計測枡内に加えて攪拌することを特徴とするセメント混合物の製造方法。 A method for producing a cement mixture comprising at least granular iron and cement ,
A concrete slab is formed in a work yard, a wall body having a predetermined height extending over a predetermined length is formed so as to surround a predetermined area on the concrete slab, and the interior surrounded by the concrete slab and the wall body is granulated. It is used as a measuring rod for measuring the capacity of iron. After the measurement, a predetermined amount of sand and a predetermined amount of cement are added to the measuring rod and stirred. A method for producing a cement mixture, characterized by stirring in addition to the above.
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