JP3799954B2 - Mixture design method for short fiber reinforced concrete with excellent workability - Google Patents
Mixture design method for short fiber reinforced concrete with excellent workability Download PDFInfo
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- JP3799954B2 JP3799954B2 JP2000117781A JP2000117781A JP3799954B2 JP 3799954 B2 JP3799954 B2 JP 3799954B2 JP 2000117781 A JP2000117781 A JP 2000117781A JP 2000117781 A JP2000117781 A JP 2000117781A JP 3799954 B2 JP3799954 B2 JP 3799954B2
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/0048—Fibrous materials
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00198—Characterisation or quantities of the compositions or their ingredients expressed as mathematical formulae or equations
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- Ceramic Engineering (AREA)
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- Curing Cements, Concrete, And Artificial Stone (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、施工性に優れた短繊維補強コンクリートに関する。
【０００２】
【従来の技術】
短繊維補強コンクリートは、硬化コンクリートの引張強度、曲げ強度、ひび割れに対する抵抗性、靱性、剪断応力、耐衝撃強度等の改善を図ることを目的として、コンクリート中に短繊維を添加したものであり、コンクリート構造物の補強を目的とした増厚工法や工場土間等に適用されている。
【０００３】
この様な短繊維を添加したコンクリートは、通常のコンクリートと比べて施工性が悪いために、施工時には充分な振動締め固めが必要となる。このため、短繊維補強コンクリートを専用のコンクリートフィニッシャーや振動機を用いて施工する際に、一般的なコンクリートの施工時に比べて大きな騒音や振動が発生し、施工に携わる作業員だけでなく、施工現場の近隣の住民にも大きな健康被害を与える可能性がある。
【０００４】
【発明が解決しようとする課題】
本発明の主な目的は、振動、騒音レベルの小さい振動機でも充分に施工可能な施工性に優れた短繊維補強コンクリートを提供することである。
【０００５】
本発明の他の目的は、簡易な試験方法によって短繊維補強コンクリートの配合組成を決定できる配合設計方法を提供することである。
【０００６】
【課題を解決するための手段】
本発明者は、上記した目的を達成すべく鋭意研究を重ねた結果、特定の関係式に基づいて短繊維を含む各成分の配合割合を決定し、更に、高性能ＡＥ減水剤の配合量を調整してコンクリートのスランプフロー値を２５０ｍｍ以上、５５０ｍｍ未満に設定することによって、材料分離を生じること無く、コンクリートの流動性を向上させることが可能となり、施工性の改善された短繊維補強コンクリートが得られることを見出し、ここに本発明を完成するに至った。
【０００７】
即ち、本発明は、下記の短繊維補強コンクリートを提供するものである。
１．短繊維を含むコンクリートであって、短繊維の容積割合（Ｆ）、粗骨材の容積割合（Ｇ）、空気の容積割合（Ｖ）、細骨材の容積割合（Ｓ）、セメントの容積割合と混和材の容積割合の合計量（Ｐ）及び水の容積割合（高性能ＡＥ減水剤を含む）（Ｗ）の合計を１とした場合に、各成分の容積割合が下記（ａ）〜（ｆ）の条件を満足し、且つ、高性能ＡＥ減水剤の配合量が、コンクリートのスランプフロー値が２５０ｍｍ以上、５５０ｍｍ未満の範囲となる量であることを特徴とする短繊維補強コンクリート：
（ａ）短繊維の容積割合：Ｆ
Ｆ≦０．０３
（ｂ）粗骨材の容積割合：Ｇ
Ｇ＜０．３−３×短繊維容積割合（Ｆ）
（ｃ）空気の容積割合：Ｖ
０．０３≦Ｖ≦０．０６
（ｄ）細骨材の容積割合：Ｓ
０．５×（１−Ｖ−Ｇ−Ｆ）≦Ｓ≦０．６×（１−Ｖ−Ｇ−Ｆ）
（ｅ）セメントの容積割合と混和材の容積割合の合計量：Ｐ
（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．４≦Ｐ≦（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．１
（ｆ）水の容積割合（高性能ＡＥ減水剤を含む）：Ｗ
Ｐ×１．１≦Ｗ≦Ｐ×１．４
２．短繊維の容積割合（Ｆ）が、０．００１≦Ｆ≦０．０３、高性能ＡＥ減水剤の使用量が、セメントと混和材の合計量を１００重量部とした場合に、０．５〜３重量部である上記項１に記載の短繊維補強コンクリート。
３．短繊維が、繊維長さ６０ｍｍ以下、アスペクト比１００以下のものである上記項１又は２に記載の短繊維補強コンクリート。
【０００８】
【発明の実施の形態】
本発明の短繊維補強コンクリートは、短繊維の容積割合（Ｆ）、粗骨材の容積割合（Ｇ）、空気の容積割合（Ｖ）、細骨材の容積割合（Ｓ）、セメントの容積割合と混和材の容積割合の合計量（Ｐ）及び水の容積割合（高性能ＡＥ減水剤を含む）（Ｗ）の合計を１とした場合に、各成分の容積割合は、下記（ａ）〜（ｆ）の条件を満足することが必要である。
（ａ）短繊維の容積割合：Ｆ
Ｆ≦０．０３
（ｂ）粗骨材の容積割合：Ｇ
Ｇ＜０．３−３×短繊維容積割合（Ｆ）
（ｃ）空気の容積割合：Ｖ
０．０３≦Ｖ≦０．０６
（ｄ）細骨材の容積割合：Ｓ
０．５×（１−Ｖ−Ｇ−Ｆ）≦Ｓ≦０．６×（１−Ｖ−Ｇ−Ｆ）
（ｅ）セメントの容積割合と混和材の容積割合の合計量：Ｐ
（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．４≦Ｐ≦（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．１
（ｆ）水の容積割合（高性能ＡＥ減水剤を含む）：Ｗ
Ｐ×１．１≦Ｗ≦Ｐ×１．４
更に、本発明の短繊維補強コンクリートは、上記した（ａ）〜（ｆ）の条件を満足した上で、スランプフロー値が２５０ｍｍ以上、５５０ｍｍ未満の範囲となる様に高性能ＡＥ減水剤の配合量を調整することが必要である。
【０００９】
以上の条件を満足する様に各成分を配合することによって、材料分離を生じること無く、コンクリートの流動性を向上させることが可能となり、施工性の改善された短繊維補強コンクリートを得ることができる。
【００１０】
以下、本発明の短繊維補強コンクリートに配合する各成分について、更に詳細に説明する。
（１）短繊維：
短繊維の容積割合は、短繊維の容積割合（Ｆ）、粗骨材の容積割合（Ｇ）、空気の容積割合（Ｖ）、細骨材の容積割合（Ｓ）、セメントの容積割合と混和材の容積割合の合計量（Ｐ）及び水の容積割合（高性能ＡＥ減水剤を含む）（Ｗ）の合計を１とした場合に、０．０３以下とする。具体的な配合割合は、曲げ強度、引張強度、衝撃強度、剪断強度、耐衝撃強度、靭性等の硬化コンクリートに対する要求特性に応じて適宜決めれば良い。短繊維の容積割合の下限値については特に限定的ではないが、通常、０．００１程度とすればよい。
【００１１】
本発明では、短繊維としては、繊維長さ６０ｍｍ程度以下であって、アスペクト比１００程度以下、好ましくは３８〜６０程度のものを好適に用いることができる。短繊維の材質については特に限定はなく、例えば、鋼、ポリプロピレン、ポリエチレン、アクリル、アラミド、ビニロン、炭素、耐アルカリガラス等のコンクリートの補強材料として使用できるものであれば何れも使用できる。
【００１２】
尚、以下の各項において、各成分の容積割合は、短繊維の場合と同様に、短繊維の容積割合（Ｆ）、粗骨材の容積割合（Ｇ）、空気の容積割合（Ｖ）、細骨材の容積割合（Ｓ）、セメントの容積割合と混和材の容積割合の合計量（Ｐ）及び水の容積割合（高性能ＡＥ減水剤を含む）（Ｗ）の合計を１とした割合である。（２）粗骨材：
粗骨材は、コンクリート構成材料中で最も大きい粒子であり、この量が増加すると、互いに接触する機会が急激に増え、かみ合いが生じて、流動性を低下させる要因となる。
【００１３】
一方、短繊維補強コンクリートに含まれる短繊維は、フレッシュコンクリート中では、複雑に絡み合うことから、コンクリートの流動性を低下させる原因となる。
【００１４】
本発明では、短繊維のこの様な作用に着目し、コンクリートに短繊維を混合することは、粗骨材量を増加させることと等価であると考え、換算係数を用いて短繊維の容積割合を粗骨材容積に換算し、粗骨材の容積と短繊維容積の換算容積の合計量を一定限度以下とすることにより、流動性の良好な短繊維補強コンクリートが得られることを見出した。具体的には、下記式に基づいて、粗骨材の容積割合（Ｇ）を決定する。
【００１５】
Ｇ＜０．３−３×短繊維容積割合（Ｆ）
上記した配合範囲において、粗骨材の容積割合（Ｇ）の上限値は、流動性、材料分離抵抗性等に基づいて定めたものであり、これを上回る配合量では、流動性、材料分離抵抗性等が低下するので好ましくない。一方、粗骨材の容積割合（Ｇ）の下限値については、特に限定は無く、構造物の条件によっては、粗骨材を配合しないことも可能であるが、ひび割れを生じ難くするためには、通常、０．０７程度以上の配合割合とすることが好ましい。
【００１６】
本発明では、粗骨材としては、ＪＩＳ Ａ ０２０３（コンクリート用語）に基づく最大寸法が２５ｍｍ程度以下のものを用いることが好ましい。尚、最大寸法２５ｍｍ以下の粗骨材とは、２５ｍｍのふるいを質量で９０％以上通過し、５ｍｍふるいに質量で８５％以上とどまる骨材である。
【００１７】
粗骨材の種類については特に限定はなく、例えば、砕石、川砂利、人工軽量骨材、再生骨材等の従来からコンクリートに配合されている各種の粗骨材を用いることができる。
（３）細骨材：
細骨材の容積割合（Ｓ）は、短繊維の容積割合（Ｆ）、粗骨材の容積割合（Ｇ）及び空気の容積割合（Ｖ）に基づいて、下記式で定める範囲とする。
【００１８】
０．５×（１−Ｖ−Ｇ−Ｆ）≦Ｓ≦０．６×（１−Ｖ−Ｇ−Ｆ）
ここで、空気の容積割合（Ｖ）は、０．０３〜０．０６の範囲とする。特に、コンクリートに耐凍害性が要求される場合には、０．０４〜０．０６の範囲とし、それ以外の場合には、０．０４未満とすることが適当である。尚、空気量は、ＪＩＳ Ａ １１２８「フレッシュコンクリートの空気量の圧力による試験方法」によって求めることができる。
【００１９】
上記した関係式は、フレッシュコンクリートのモルタル中に含まれる細骨材の割合が５０〜６０％の範囲内であることを意味するものである。細骨材の割合をこの範囲とすることによって、コンクリートの材料分離抵抗性を低下させることなく、流動性を向上させることができる。
【００２０】
細骨材としては、例えば、川砂、山砂、陸砂、砕砂、人工軽量骨材等を用いることができる。
（４）セメント及び混和材：
セメントの容積割合と混和材の容積割合の合計量（Ｐ）は、短繊維の容積割合（Ｆ）、粗骨材の容積割合（Ｇ）、空気の容積割合（Ｖ）及び細骨材の容積割合（Ｓ）に基づいて、下記式で定める範囲とする。
【００２１】
（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．４≦Ｐ≦（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．１
ここで、１−Ｖ−Ｇ−Ｆ−Ｓは、コンクリート中のセメント、混和材及び水の容積割合の合計量（Ｐ＋Ｗ）を表すものであり、この関係式より、水の容積割合（高性能ＡＥ減水剤を含む）（Ｗ）は、セメントの容積割合と混和材の容積割合の合計量（Ｐ）に対して、下記式で示す範囲となる。
【００２２】
Ｐ×１．１≦Ｗ≦Ｐ×１．４
上記した粉体（セメントと混和材）に対する水の容積割合は、従来の短繊維補強コンクリートにおける粉体（セメントと混和材）に対する水の容積割合と比べて少量である。本発明では、水の配合割合をこの様な範囲とすることによって、材料分離抵抗性に優れたコンクリートとすることができ、施工性を向上させることが可能となる。
【００２３】
本発明の短繊維補強コンクリートにおいて、セメントとしては、特に限定はなく、硬化コンクリートに対して要求される性質に応じて、通常用いられているセメントから適宜選択して用いればよい。例えば、ポルトランドセメント（ＪＩＳＲ ５２１０）、高炉セメント（ＪＩＳ Ｒ ５２１１）、シリカセメント（ＪＩＳ Ｒ ５２１２）、フライアッシュセメント（ＪＩＳ Ｒ ５２１３）等の各種セメントを用いることができる。
【００２４】
混和材としては、例えば、高炉スラグ微粉末、フライアッシュ、シリカフューム、石灰石微粉末等のブレーン比表面積が２０００ｃｍ2／ｇ程度以上の微粉末を好適に用いることができる。
【００２５】
混和材は、必ずしも使用する必要はなく、使用する場合には、その種類、使用量等については、目的とする硬化コンクリートに要求される性質に応じて適宜決めれば良い。一般的には、セメントと混和材の合計量を１００重量部とした場合に、高炉スラグ微粉末は６０重量部以下、フライアッシュは４０重量部以下、シリカフュームは３０重量部以下、石灰石微粉末は５０重量部以下の使用量とすればよい。
（５）高性能ＡＥ減水剤：
高性能ＡＥ減水剤の種類については特に限定はなく、公知の高性能ＡＥ減水剤から適宜選択して用いればよい。特に、経時時間に伴うフレッシュコンクリートの性質の変化が小さいものを選択することが好ましく、例えば、ポリカルボン酸系、ナフタレン系等の高性能ＡＥ減水剤を好適に用いることができる。
【００２６】
高性能ＡＥ減水剤の使用量は、フレッシュコンクリートのスランプフロー値が２５０ｍｍ以上、５５０ｍｍ未満の範囲となる量とすることが必要である。スランプフロー値が上記範囲内となるように添加する場合には、高性能ＡＥ減水剤の添加量は、セメントと混和材の合計量を１００重量部とした場合に、通常０．５〜３重量部程度の範囲となる。尚、本発明において、スランプフロー値は土木学会規準ＪＳＣＥ−Ｆ５０３−１９９９に基づいて測定した値である。
【００２７】
コンクリートのスランプフロー値を２５０ｍｍ以上、５５０ｍｍ未満の範囲とすることによって、良好な流動性と材料分離抵抗性を有し、施工性に優れた短繊維補強コンクリートとなる。
【００２８】
尚、上記した２５０ｍｍ以上、５５０ｍｍ未満のスランプフロー値の範囲は、スランプ値で表すと１２〜２５ｃｍ程度の範囲となる。
【００２９】
【発明の効果】
本発明によれば、上記した条件を満足する配合組成とすることによって、短繊維補強コンクリートにおいて、材料分離を生じること無く、コンクリートの流動性を向上させることが可能となる。その結果、施工性の改善された短繊維補強コンクリートを得ることができ、軽微な振動で充填施工が可能となり、施工時における騒音や振動の発生を抑制することができる。
【００３０】
また、本発明によれば、従来の短繊維補強コンクリートでは、粗骨材、細骨材、セメント、混和材等の配合量について、数多くの試し練りを行い、スランプ試験やフロー試験を実施して決定していたものを、上記各式に基づいて配合割合を決定することにより、少ない回数の試し練りによって目的に応じた配合組成のコンクリートを得ることができる。このため、配合設計を簡単に行うことができる。
【００３１】
【実施例】
以下、実施例を挙げて本発明を更に詳細に説明する。
実施例１〜３及び比較例１〜２
下記表１に示す配合の短繊維補強コンクリートを調製した。配合組成の残部は空気であり、配合割合は０．０３１である。尚、高性能ＡＥ減水剤の量は、セメント重量に対する重量％として示す。使用した各成分は、次の通りである。
（１）短繊維
タフグリップ（商標名、ブリジストン社製）鋼製、繊維長３０ｍｍ
（２）セメント
普通ポルトランドセメント（住友大阪セメント（株）製、比重３．１５）
（３）粗骨材
高槻産砕石、表乾比重２．７０、粗粒率６．８７、実積率５８．６％
（４）細骨材
野州川産川砂、表乾比重２．５９、粗粒率３．０３、実積率６６．９％
（５）高性能ＡＥ減水剤
ポリカルボン酸系高性能ＡＥ減水剤（商標名：レオビルドＳＰ８Ｓ−ｘ２、エヌエムビー社製）レオビルドＳＰ８Ｓ−ｘ２（商標名、エヌエムビー社製）
得られた各コンクリートについて、スランプフロー値及びスランプ値の測定と施工性の評価のための試験を行った。各試験方法は、以下の通りである。
＊スランプフロー値
土木学会規準ＪＳＣＥ−Ｆ５０３−１９９９に基づいて測定した。
＊スランプ値
ＪＩＳ Ａ １１０１に基づいて測定した。
＊施工性の評価
大きさが３５０ｍｍ×３５０ｍｍ×２００ｍｍ（深さ）であって、底板を取り外しできる容器（容量２４．５リットル）を、φ１０ｍｍ、５０ｍｍ間隔の孔を形成したメッシュの上に配置した。このメッシュには、バイブレーターを取り付け、振動可能とした。
【００３２】
上記容器にコンクリートを充填した後、容器の底板を取り外し、その瞬間にバイブレーターをスタートさせて、メッシュを振動させた。
【００３３】
容器内の全てのコンクリートが、メッシュを通過するまでに要する時間を測定して、施工性を評価した。
以上の結果を下記表１に示す。
【００３４】
【表１】
表１から明らかなように、本発明の全ての要件を満足する実施例１〜３のコンクリートは、メッシュ通過時間が短く施工性が良好であった。
【００３６】
一方、スランプ値の低い比較例１のコンクリートと水セメント比の高い比較例２のコンクリートは、何れもメッシュ通過時間が長く施工性に劣るものであった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a short fiber reinforced concrete excellent in workability.
[0002]
[Prior art]
Short fiber reinforced concrete is the addition of short fibers in concrete for the purpose of improving the tensile strength, bending strength, resistance to cracking, toughness, shear stress, impact strength of hardened concrete, It is applied to the thickening method for the reinforcement of concrete structures and factory soil.
[0003]
Since concrete with such short fibers added has poor workability compared to normal concrete, sufficient vibration compaction is required during construction. For this reason, when constructing short fiber reinforced concrete using a dedicated concrete finisher or vibrator, loud noise and vibration are generated compared to general concrete construction, and not only workers involved in construction but also construction There is also the possibility of serious health damage to the local residents in the field.
[0004]
[Problems to be solved by the invention]
The main object of the present invention is to provide a short fiber reinforced concrete excellent in workability that can be sufficiently constructed even with a vibrator having low vibration and noise levels.
[0005]
Another object of the present invention is to provide a blending design method capable of determining the blending composition of short fiber reinforced concrete by a simple test method.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above-mentioned object, the present inventor determined the blending ratio of each component including short fibers based on a specific relational expression, and further determines the blending amount of the high-performance AE water reducing agent. By adjusting and setting the concrete slump flow value to 250 mm or more and less than 550 mm, the fluidity of the concrete can be improved without causing material separation, and the short fiber reinforced concrete with improved workability is obtained. The present invention has been found and the present invention has been completed.
[0007]
That is, the present invention provides the following short fiber reinforced concrete.
1. Concrete containing short fibers, short fiber volume ratio (F), coarse aggregate volume ratio (G), air volume ratio (V), fine aggregate volume ratio (S), cement volume ratio And the total volume ratio (P) of the admixture and the volume ratio of water (including the high performance AE water reducing agent) (W) is 1, the volume ratio of each component is the following (a) to ( Short fiber reinforced concrete satisfying the condition f), and the amount of the high-performance AE water reducing agent is such that the slump flow value of the concrete is in the range of 250 mm or more and less than 550 mm:
(A) Short fiber volume ratio: F
F ≦ 0.03
(B) Volume ratio of coarse aggregate: G
G <0.3-3 × short fiber volume ratio (F)
(C) Volume ratio of air: V
0.03 ≦ V ≦ 0.06
(D) Volume ratio of fine aggregate: S
0.5 × (1-VGFG) ≦ S ≦ 0.6 × (1-VGFG)
(E) Total amount of cement volume ratio and admixture volume ratio: P
(1-VGFS) /2.4≦P≦ (1-VGFS) /2.1
(F) Volume ratio of water (including high performance AE water reducing agent): W
P × 1.1 ≦ W ≦ P × 1.4
2. When the short fiber volume fraction (F) is 0.001 ≦ F ≦ 0.03 and the amount of high-performance AE water reducing agent used is 100 parts by weight of the total amount of cement and admixture, 0.5 to Item 2. The short fiber reinforced concrete according to Item 1, which is 3 parts by weight.
3. Item 3. The short fiber reinforced concrete according to Item 1 or 2, wherein the short fiber has a fiber length of 60 mm or less and an aspect ratio of 100 or less.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The short fiber reinforced concrete of the present invention has a short fiber volume ratio (F), a coarse aggregate volume ratio (G), an air volume ratio (V), a fine aggregate volume ratio (S), and a cement volume ratio. And the total volume ratio (P) of the admixture and the volume ratio of water (including the high-performance AE water reducing agent) (W) is 1, the volume ratio of each component is the following (a) to It is necessary to satisfy the condition (f).
(A) Short fiber volume ratio: F
F ≦ 0.03
(B) Volume ratio of coarse aggregate: G
G <0.3-3 × short fiber volume ratio (F)
(C) Volume ratio of air: V
0.03 ≦ V ≦ 0.06
(D) Volume ratio of fine aggregate: S
0.5 × (1-VGFG) ≦ S ≦ 0.6 × (1-VGFG)
(E) Total amount of cement volume ratio and admixture volume ratio: P
(1-VGFS) /2.4≦P≦ (1-VGFS) /2.1
(F) Volume ratio of water (including high performance AE water reducing agent): W
P × 1.1 ≦ W ≦ P × 1.4
Furthermore, the short fiber reinforced concrete according to the present invention contains the high-performance AE water reducing agent so that the slump flow value is in the range of 250 mm or more and less than 550 mm while satisfying the above conditions (a) to (f). It is necessary to adjust the amount.
[0009]
By blending each component so as to satisfy the above conditions, the fluidity of the concrete can be improved without causing material separation, and a short fiber reinforced concrete with improved workability can be obtained. .
[0010]
Hereafter, each component mix | blended with the short fiber reinforced concrete of this invention is demonstrated in detail.
(1) Short fiber:
The short fiber volume ratio is mixed with the short fiber volume ratio (F), the coarse aggregate volume ratio (G), the air volume ratio (V), the fine aggregate volume ratio (S), and the cement volume ratio. When the total of the volume ratio (P) of the material and the volume ratio of water (including the high-performance AE water reducing agent) (W) is 1, it is set to 0.03 or less. A specific blending ratio may be appropriately determined according to required properties for the hardened concrete such as bending strength, tensile strength, impact strength, shear strength, impact strength, and toughness. The lower limit of the short fiber volume ratio is not particularly limited, but is usually about 0.001.
[0011]
In the present invention, short fibers having a fiber length of about 60 mm or less and an aspect ratio of about 100 or less, preferably about 38 to 60 can be suitably used. The material of the short fiber is not particularly limited, and any material can be used as long as it can be used as a reinforcing material for concrete such as steel, polypropylene, polyethylene, acrylic, aramid, vinylon, carbon, and alkali-resistant glass.
[0012]
In each of the following items, the volume ratio of each component is the same as in the case of short fibers, but the short fiber volume ratio (F), the coarse aggregate volume ratio (G), the air volume ratio (V), Fine aggregate volume ratio (S), total volume ratio of cement and admixture volume ratio (P), and water volume ratio (including high-performance AE water reducing agent) (W) It is. (2) Coarse aggregate:
Coarse aggregate is the largest particle in the concrete constituting material, and when this amount increases, the chance of contact with each other increases rapidly, and meshing occurs, causing a decrease in fluidity.
[0013]
On the other hand, the short fibers contained in the short fiber reinforced concrete are intertwined in the fresh concrete in a complicated manner, which causes a decrease in the fluidity of the concrete.
[0014]
In the present invention, paying attention to such action of short fibers, mixing short fibers with concrete is considered to be equivalent to increasing the amount of coarse aggregate, and the volume ratio of short fibers using a conversion factor It was found that a short fiber reinforced concrete with good fluidity can be obtained by converting to a coarse aggregate volume and making the total amount of the coarse aggregate volume and the short fiber volume converted volume equal to or less than a certain limit. Specifically, the volume ratio (G) of the coarse aggregate is determined based on the following formula.
[0015]
G <0.3-3 × short fiber volume ratio (F)
In the blending range described above, the upper limit value of the volume ratio (G) of the coarse aggregate is determined based on fluidity, material separation resistance, and the like. This is not preferable because the properties and the like are lowered. On the other hand, the lower limit value of the volume ratio (G) of the coarse aggregate is not particularly limited, and depending on the conditions of the structure, it is possible not to mix the coarse aggregate, but to make it difficult to cause cracks. Usually, it is preferable to set the blending ratio to about 0.07 or more.
[0016]
In the present invention, it is preferable to use a coarse aggregate having a maximum dimension of about 25 mm or less based on JIS A 0203 (concrete term). The coarse aggregate having a maximum dimension of 25 mm or less is an aggregate that passes through a 25 mm sieve by 90% or more and remains on a 5 mm sieve by 85% or more by mass.
[0017]
There are no particular limitations on the type of coarse aggregate. For example, various types of coarse aggregate that have been conventionally blended in concrete, such as crushed stone, river gravel, artificial lightweight aggregate, and recycled aggregate, can be used.
(3) Fine aggregate:
The volume ratio (S) of the fine aggregate is set in the range defined by the following formula based on the volume ratio (F) of the short fibers, the volume ratio (G) of the coarse aggregate, and the volume ratio (V) of the air.
[0018]
0.5 × (1-VGFG) ≦ S ≦ 0.6 × (1-VGFG)
Here, the volume ratio (V) of air is in the range of 0.03 to 0.06. In particular, when the frost damage resistance is required for concrete, the range is 0.04 to 0.06, and in other cases, it is appropriate to be less than 0.04. The amount of air can be determined according to JIS A 1128 “Test method by pressure of air amount of fresh concrete”.
[0019]
The above relational expression means that the proportion of fine aggregate contained in the mortar of fresh concrete is in the range of 50 to 60%. By setting the proportion of the fine aggregate within this range, the fluidity can be improved without reducing the material separation resistance of the concrete.
[0020]
As the fine aggregate, for example, river sand, mountain sand, land sand, crushed sand, artificial lightweight aggregate and the like can be used.
(4) Cement and admixture:
The total volume ratio (P) of the cement volume ratio and the admixture volume ratio is the short fiber volume ratio (F), the coarse aggregate volume ratio (G), the air volume ratio (V), and the fine aggregate volume. Based on the ratio (S), the range is determined by the following formula.
[0021]
(1-VGFS) /2.4≦P≦ (1-VGFS) /2.1
Here, 1-VGFS represents the total amount (P + W) of the cement, admixture, and water in the concrete (P + W). (Including AE water reducing agent) (W) is a range represented by the following formula with respect to the total amount (P) of the volume ratio of the cement and the volume ratio of the admixture.
[0022]
P × 1.1 ≦ W ≦ P × 1.4
The volume ratio of water to the above-described powder (cement and admixture) is smaller than the volume ratio of water to powder (cement and admixture) in conventional short fiber reinforced concrete. In this invention, it can be set as the concrete excellent in material-separation resistance by making the mixture ratio of water into such a range, and it becomes possible to improve workability.
[0023]
In the short fiber reinforced concrete of the present invention, the cement is not particularly limited, and may be appropriately selected from commonly used cements according to the properties required for the hardened concrete. For example, various cements such as Portland cement (JISR 5210), blast furnace cement (JIS R 5211), silica cement (JIS R 5212), fly ash cement (JIS R 5213), and the like can be used.
[0024]
As the admixture, for example, a fine powder having a brain specific surface area of about 2000 cm 2 / g or more, such as blast furnace slag fine powder, fly ash, silica fume, and limestone fine powder, can be suitably used.
[0025]
The admixture does not necessarily need to be used, and when used, the type, amount of use, and the like may be appropriately determined according to the properties required for the target hardened concrete. Generally, when the total amount of cement and admixture is 100 parts by weight, blast furnace slag fine powder is 60 parts by weight or less, fly ash is 40 parts by weight or less, silica fume is 30 parts by weight or less, and limestone fine powder is The amount used may be 50 parts by weight or less.
(5) High performance AE water reducing agent:
The type of the high-performance AE water reducing agent is not particularly limited, and may be appropriately selected from known high-performance AE water reducing agents. In particular, it is preferable to select one having a small change in properties of fresh concrete with time, and for example, a high-performance AE water reducing agent such as a polycarboxylic acid type or a naphthalene type can be suitably used.
[0026]
The amount of the high-performance AE water reducing agent used must be such that the slump flow value of fresh concrete is in the range of 250 mm or more and less than 550 mm. When added so that the slump flow value is within the above range, the amount of the high-performance AE water reducing agent is usually 0.5 to 3 weights when the total amount of cement and admixture is 100 parts by weight. Part range. In the present invention, the slump flow value is a value measured based on JSCE-F503-1999.
[0027]
By making the slump flow value of concrete into the range of 250 mm or more and less than 550 mm, it becomes a short fiber reinforced concrete having good fluidity and material separation resistance and excellent workability.
[0028]
In addition, the range of the above-mentioned slump flow value of 250 mm or more and less than 550 mm is a range of about 12 to 25 cm in terms of the slump value.
[0029]
【The invention's effect】
According to the present invention, it is possible to improve the fluidity of the concrete without causing material separation in the short fiber reinforced concrete by setting the composition to satisfy the above-described conditions. As a result, short fiber reinforced concrete with improved workability can be obtained, filling work can be performed with slight vibration, and noise and vibration during construction can be suppressed.
[0030]
In addition, according to the present invention, in the conventional short fiber reinforced concrete, a lot of trial kneading is performed on the blending amount of coarse aggregate, fine aggregate, cement, admixture, etc., and a slump test and a flow test are performed. By determining the blending ratio of what has been determined based on the above formulas, concrete having a blending composition according to the purpose can be obtained by a small number of trial kneading. For this reason, a compounding design can be performed easily.
[0031]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
Examples 1-3 and Comparative Examples 1-2
Short fiber reinforced concrete having the composition shown in Table 1 below was prepared. The balance of the blend composition is air, and the blend ratio is 0.031. In addition, the quantity of a high performance AE water reducing agent is shown as weight% with respect to cement weight. Each component used is as follows.
(1) Short fiber tough grip (trade name, manufactured by Bridgestone) made of steel, fiber length 30 mm
(2) Cement ordinary portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd., specific gravity 3.15)
(3) Coarse aggregate from Takatsuki, coarse aggregate, surface dry specific gravity 2.70, coarse grain ratio 6.87, actual volume ratio 58.6%
(4) Fine aggregate Noshugawa river sand, surface dry specific gravity 2.59, coarse grain ratio 3.03, actual volume ratio 66.9%
(5) High-performance AE water-reducing agent Polycarboxylic acid-based high-performance AE water-reducing agent (trade name: Leobuild SP8S-x2, manufactured by NM) Leobuild SP8S-x2 (trade name, manufactured by NM)
About each obtained concrete, the test for the measurement of slump flow value and slump value, and evaluation of workability was done. Each test method is as follows.
* Slump flow value was measured based on JSCE-F503-1999 standard of Japan Society of Civil Engineers.
* Slump value Measured based on JIS A 1101.
* The evaluation size of workability is 350 mm x 350 mm x 200 mm (depth), and a container (capacity: 24.5 liters) from which the bottom plate can be removed was placed on a mesh formed with holes of φ10 mm and 50 mm intervals. . A vibrator was attached to this mesh to enable vibration.
[0032]
After filling the container with concrete, the bottom plate of the container was removed, and at that moment, the vibrator was started to vibrate the mesh.
[0033]
The workability was evaluated by measuring the time required for all the concrete in the container to pass through the mesh.
The above results are shown in Table 1 below.
[0034]
[Table 1]
As is clear from Table 1, the concrete of Examples 1 to 3 that satisfies all the requirements of the present invention had a short mesh passage time and good workability.
[0036]
On the other hand, both the concrete of Comparative Example 1 having a low slump value and the concrete of Comparative Example 2 having a high water cement ratio had a long mesh passage time and poor workability.
Claims (3)
（ａ）短繊維の容積割合：Ｆ
Ｆ≦０．０３
（ｂ）粗骨材の容積割合：Ｇ
Ｇ＜０．３−３×短繊維容積割合（Ｆ）
（ｃ）空気の容積割合：Ｖ
０．０３≦Ｖ≦０．０６
（ｄ）細骨材の容積割合：Ｓ
０．５×（１−Ｖ−Ｇ−Ｆ）≦Ｓ≦０．６×（１−Ｖ−Ｇ−Ｆ）
（ｅ）セメントの容積割合と混和材の容積割合の合計量：Ｐ
（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．４≦Ｐ≦（１−Ｖ−Ｇ−Ｆ−Ｓ）／２．１
（ｆ）水の容積割合（高性能ＡＥ減水剤を含む）：Ｗ
Ｐ×１．１≦Ｗ≦Ｐ×１．４It is a blending design method for concrete containing short fibers, the volume ratio of short fibers (F), the volume ratio of coarse aggregate (G), the volume ratio of air (V), the volume ratio of fine aggregate (S), When the sum of the volume ratio of cement and the volume ratio of admixture (P) and the volume ratio of water (including high-performance AE water reducing agent) (W) is 1, the volume ratio of each component is as follows ( satisfies the condition of a) ~ (f), and, the amount of high-performance AE water reducing agent, the slump flow value of the concrete is 250mm or more, the short fiber reinforced, characterized in that the amount in the range of less than 550mm Concrete mix design method :
(A) Short fiber volume ratio: F
F ≦ 0.03
(B) Volume ratio of coarse aggregate: G
G <0.3-3 × short fiber volume ratio (F)
(C) Volume ratio of air: V
0.03 ≦ V ≦ 0.06
(D) Volume ratio of fine aggregate: S
0.5 × (1-VGFG) ≦ S ≦ 0.6 × (1-VGFG)
(E) Total amount of cement volume ratio and admixture volume ratio: P
(1-VGFS) /2.4≦P≦ (1-VGFS) /2.1
(F) Volume ratio of water (including high performance AE water reducing agent): W
P × 1.1 ≦ W ≦ P × 1.4
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