JP4420480B2 - High-strength cementitious composition - Google Patents
High-strength cementitious composition Download PDFInfo
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- JP4420480B2 JP4420480B2 JP36058097A JP36058097A JP4420480B2 JP 4420480 B2 JP4420480 B2 JP 4420480B2 JP 36058097 A JP36058097 A JP 36058097A JP 36058097 A JP36058097 A JP 36058097A JP 4420480 B2 JP4420480 B2 JP 4420480B2
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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
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2641—Polyacrylates; Polymethacrylates
- C04B24/2647—Polyacrylates; Polymethacrylates containing polyether side chains
-
- 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
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2664—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of ethylenically unsaturated dicarboxylic acid polymers, e.g. maleic anhydride copolymers
- C04B24/267—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of ethylenically unsaturated dicarboxylic acid polymers, e.g. maleic anhydride copolymers containing polyether side chains
-
- 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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/40—Surface-active agents, dispersants
- C04B2103/408—Dispersants
Description
【０００１】
【発明の属する技術分野】
本発明は、流動性に優れた高強度のセメント系組成物に関し、より詳しくは、流動性が高いので成形が容易であり、かつ硬化体の強度が大きいセメント系組成物に関するものである。
【０００２】
【従来の技術】
セメント系組成物の代表としてコンクリートがある。コンクリートには経済性を高めると共にその乾燥による収縮を抑えてひび割れを防止するために容積比で７割程度の骨材が含まれている。この骨材には平均粒径５mm以上の粗骨材と、これより平均粒径が小さい細骨材とが用いられている。粗骨材を用いる目的は材料の充填率を高めることにより成形に必要な流動性を少ない水量で得られるようにすることにある。水量を低減すれば相対的に水セメント比が小さくなり、セメントペースト部分を高強度化する上で有利になる。
【０００３】
一方、粒径の大きな粗骨材を用いることは、粗骨材とマトリックスとで硬化体の均質性が異なるので、粗骨材と他のマトリクスとが馴染まず、その界面が破壊しやすいものとなる。このため、粗骨材の使用は硬化体の強度を高めるうえでは欠点にもなる。例えば、圧縮強度が１５０N/mm2以上の高強度の硬化体を得ようとする場合、また曲げ強度を高めようとする場合などは、粗骨材を用いることは好ましいとは言えない。他方、硬化体の組織を均質化するために骨材の粒径を小さくすると成形に必要な流動性を得るための水量が増加し、やはり高強度化のためには好ましくない。そこで、流動性と低水量を両立させるために分散剤が用いられるが、従来のものはその効果が不十分である。
【０００４】
【発明の解決課題】
以上のように、従来のセメント系組成物は成形に必要な流動性と硬化後の強度が不十分である。本発明は、このような従来の問題を解決したセメン卜系組成物を提供することを目的とする。
【０００５】
【課題を解決する手段】
すなわち、本発明は、(１)セメントと骨材に分散剤と水を加えたものを主体とする組成物であって、骨材が粒径５mm以下の粉粒体でシリカフュームを含有するものであり、添加水量が体積比で２５％以下、分散剤が一般式−(ΑＯ)ｎ−Ｒ（ＡＯは炭素数２から１２のオキシアルキレン基、Ｒは水素あるいは炭素数２から１２の炭化水素基、(ＡＯ)ｎはｎがオキシアルキレン基の平均付加モル数５０以上のポリオキシアルキレン基）で表される分子構造を有するものであり、添加水量が全材料の合計体積に対し体積比で１０〜２５％、骨材／セメント(重量比)が０.５〜４で、分散剤の添加量が粒径７５μm以下の骨材およびセメントに対して０.１〜５重量％であり、かつ硬化後に１５０N/mm2以上の圧縮強度を発現することを特徴とするセメント系組成物に関する。
【０００６】
本発明の上記セメント系組成物は、（２）ポリオキシアルキレン基と共にカルボキシル基および/またはスルホン基を有する分散剤を用いたもの、（３）ポリオキシアルキレン基が分子中５０重量％以上である分散剤を用いたもの、（４）骨材が、セメント１００重量部に対して、粒径１μm未満の粒子４０重量部以下、粒径１μm〜７５μmの粒子２００重量部以下、粒径７５μm〜５mmの粒子４００重量部以下であるものを含む。
【０００７】
【発明の実施態様】
以下に本発明を実施例と共に詳細に説明する。本発明のセメント系組成物は、セメントと骨材の配合に分散剤と水を加えてなる組成物であって、骨材の粒径を細骨材以下の範囲に限定して出来るだけ組成物を均質化し、さらに特定の分子構造を有する分散剤を添加することにより添加水量を低減しながら優れた流動性と材料強度を達成したものである。具体的には、骨材を粒径５mm以下の粉粒体とし、添加水量を体積比で２５％以下に限定すると共に、分散剤として一般式−(ＡＯ)ｎ−Ｒ（ＡＯは炭素数２から１２のオキシアルキレン基、Ｒは水素あるいは炭素数２から１２の炭化水素基、(ΑＯ)ｎはｎがオキシアルキレン基の平均付加モル数５０以上のポリオキシアルキレン基）で表される分子構造を有するものを用いたものである。
【０００８】
( Ｉ ) セメント
本発明に用いられるセメントの種類は限定されない。ポルトランドセメント、混合セメント、速硬セメントなどを用いることができる。ポルトランドセメントは普通、中庸熱、早強、超早強、耐硫酸塩、低熱、白色の各ポルトランドセメントを用いることができる。中庸熱、耐硫酸塩、低熱の各ポルトランドセメントはアルミネート鉱物(Ｃ3Α)の含有量が少なく、流動性が良いので好ましい。混合セメントにはフライアッシュセメント、高炉セメント、シリカセメントがあるが何れも本発明に用いることができる。混合セメントは組成物中のポルトランドセメント分が他のセメントよりも相対的に少ないので流動性を高める点では好ましい。速硬セメントは短時間で硬化するので流動性が早く失われるが、早期に強度の発現を求められる場合には効果的である。
【０００９】
(II) 骨材
本発明において用いる骨材は粒径５mm以下のものである。なお、本発明において粒径５mm以下とは、日本工業規格(JIS A 1102−1989)に規定される骨材の篩分け試験において、５mm篩上の残量が１０％未満であることを云う。好ましくは、１.２mm篩上の残量が１０％未満のものが適当である。
【００１０】
本発明の骨材は、流動性を高めると共に組成物の充填度および強度を高めるために、以下の粒度分布を有するものが好ましい。即ち、セメント１００重量部に対して、１μm以下の粒子が４０重量部以下、ｌμm〜７５μmの粒子が２００重量部以下、７５μm以上の粒子が４００重量部以下であって、骨材(Ρ)とセメント(Ｃ)の重量比(Ρ/Ｃ)が０.５〜４であるものが好ましい。
【００１１】
骨材の材質は限定されない。なお、シリカ質の骨材でセメントとポゾラン反応するものは高強度を得るうえで好ましい。特に粒径の小さいものはポゾラン反応の点でシリカ質含有量の高いものがより好ましい。シリカ質骨材の例としては、シリカフューム、シリカゾル、沈降シリカ、フライアッシュ、スラグ、火山灰、珪砂、岩石粉末、河川砂、山砂、陸砂、海砂、砕砂がある。なお、シリカと石灰のバランスを調整するために石灰石微粉末、石灰石砕砂を用いることも有益である。
【００１２】
(III)分散剤
本発明に用いる分散剤は、その分子中に、一般式−(ＡＯ)ｎ−Ｒ（ＡＯは炭素数２から１２のオキシアルキレン基、Ｒは水素あるいは炭素数２から１２の炭化水素基、(ＡＯ)ｎはｎがオキシアルキレン基の平均付加モル数で５０以上のポリオキシアルキレン基）で表される分子構造を有するものである。分散剤の分子中に含まれるポリオキシアルキレン基は、その立体障害効果により組成物の材料粒子どうしを反発させて分散性を高める。特にナフタレンスルホン酸では分散が難しかった低水粉体比の系において有効にその効果を発揮する。
【００１３】
このような立体障害効果によって材料粒子どうしを反発させるには、オキシアルキレン基の平均付加モル数(一般式のｎ)が重要である。平均付加モル数ｎが大きいほどその効果が大きい。具体的にはｎ＝５０以上が良い。平均付加モル数ｎの上限は特に限定されないが、製造の経済性からは２００以下が妥当であろう。なお、分散剤は分子中に異なる平均付加モル数ｎのオキシアルキレン基を２種以上含有するものでも良い。ポリオキシアルキレン基のうち製造上経済的であるのはポリオキシエチレン基であるが、その他にポリオキシプロピレン基等でも良い。また、２種以上のオキシアルキレン基を同一鎖上に持つものでも良い。
【００１４】
さらに、本発明に用いる分散剤は、セメントに吸着して効果を高めるように、カルボキシル基および／またはスルホン基をポリオキシエチレンと共に有するものが好ましい。具体的な例として、(i)アクリレート、メタクリレートまたはその誘導体などのアクリル酸系の単量体と、これら単量体と共重合可能なポリオキシアルキレン基を持つ化合物を必須成分とする共重合体、(ii)無水マレイン酸と、無水マレイン酸と共重合可能なポリオキシアルキレンを持つ化合物との共重合物、(iii)上記(i)(ii)にアリルスルホン酸等のスルホン酸化合物を成分として重合した共重合物、(iV)芳香族化合物とホルムアルデヒド共縮合可能なポリオキシアルキレン基を持つ化合物とホルムアルデヒド共縮合物が例示される。なお、これらの共重合体や共縮合物は塩の形でも良い。
【００１５】
これらのポリオキシアルキレン基を持つ化合物(以下、ポリオキシアルキレン化合物と云う)を必須成分とするセメント分散剤は、例えば、アクリル酸系の共重合物は特開昭58-74552号、特開平01-226757号、特開平6-206750号、特開平07-109156号、特開平07-126053号、特開平08-12396号、特開平09-27850号などに記載されており、また無水マレイン酸の共重合物は特開昭63-285140号、特開平05-310458号、特開平09-255740号などに記載されている。また、芳香族化合物とのホルムアルデヒド共縮合物の例は特開平06-340459号、特開平07-109158号に記載されている。しかし、これらは何れもその成分を示したものに過ぎず、セメント系組成物の強度を高める目的でその付加モル数ｎを検討したものは知られていない。しかも、これらに記載されている組成物の強度は本発明よりも格段に低い。例えば、高強度セメント組成物の提供を目的とした特開平6-206750号においてさえ、実施例に示された最高の強度は１３５N/mm2に止まっており、本発明のような１５０N/mm2水準の高強度セメント組成物を提供するものではない。
【００１６】
本発明に用いる分散剤において、ポリオキシアルキレン基の分子中の含有量は、５０重量％以上が適当である。５０重量％未満ではポリオキシアルキレン基による立体障害効果による粒子分散効果が十分得られず、セメント系組成物の流動性が不十分になる。
【００１７】
分散剤の添加量は、粒径７５μm以下の骨材およびセメントに対して重量比で、０.１〜５％が適当である。粒径７５μm以下の骨材は組成物の流動性を低下させるので、分散剤によって流動性の低下を防止する。分散剤の添加量が上記範囲より少ないとセメント系組成物の流動性が大幅に低く、また、この添加量が上記範囲より多過ぎるとセメント系組成物の強度発現を阻害するので好まくない。
【００１８】
本発明のセメント系組成物は、可溶性カルシウム塩を添加することにより強度の発現を促進することができる。入手が容易で利用しやすい可溶性カルシウム塩の例として、亜硝酸カルシウム、硝酸カルシウム、ギ酸カルシウム、チオシアン酸カルシウム、塩化カルシウムなどがある。これらの添加量は０.１〜５重量％が適当である。
【００１９】
本発明のセメント系組成物に添加される水量は、全材料の合計体積に対し体積比で２５％以下であり、１０％〜２５％が好ましい。特に高強度を得ようとする場合には２０％以下が好ましい。水量が１０％未満では組成物の流動性が失われる。また、添加水量が２５％を上回ると強度が低下する。
【００２０】
本発明のセメント系組成物を硬化させる場合、養生については特別の処理を必要としない。なお、４５℃以上の温度に３時間以上置くと、より高強度の硬化体を得ることができる。
【００２１】
【発明の効果】
本発明のセメント系組成物は、硬化後に１５０N/mm2以上の圧縮強度を得ることができる。このように非常に緻密で硬化体の強度が大きく、しかも耐久性に優れるので、土木、建築、機械等の各分野において広く利用することができ、従来のコンクリートに代えて使用することにより更に耐久性を高めることができる。また、樹脂や鋼材の代替としての使用も可能である。
更に、本発明のセメント系組成物は流動性に優れるので、施工性が良く、流し込みが可能でポンプを使い容易に施工することができる。
【００２２】
【実施例】
以下、本発明を実施例によって具体的に示す。
実施例１
各材料の配合比が、中庸熱ポルトランドセメント３５体積部に、骨材としてシリカフューム１０体積部、珪石粉末１５体積部、豊浦珪砂２０体積部を加え、これに表１に示す分散剤を含む水２０体積部を添加してセメント組成物とした。このセメント組成物１リットルをホバートミキサーで１０分間練り混ぜ、これをガラス板上に置いたリング(D25mm×H20mm)に流し込み、リングを引き上げて丸く広がった組成物の長径と短径を測定し、その平均値をフロー値として表し、流動性を評価した。また、この組成物を用いて角柱の供試体(2×2×H3cm)を成形し、２０℃の水中養生を２８日、８０℃の水中養生を３日行った後に圧縮強度を日本工業規格(JIS A 1108)に従って測定した。この結果を表１に示した。
なお、骨材は、セメント１００重量部に対し、１μm以下の粒子２３重量部、１〜７５μmの粒子３９重量部、７５μm〜５mmの粒子５０重量部からなるものである。分散剤の添加量はセメント１００重量部に対し１重量部である。なお、表１に示す分散剤の成分は表２の通りである。
【００２３】
表１に示すように、分散剤中のオキシエチレンの付加モル数の多いものほど組成物の分散性が高くなり、組成物が均質化されると共に流動性も高められる。この作用によって気泡が少なく、かつ均質な成型体が得られるので成形体の圧縮強度が向上している。
また、カルボキシル基とスルホン基を同時に持つものは初期の流動性が高く、かつ流動性の経時変化を小さくすることを可能としている。一方、オキシエチレンの付加モル数が本発明より少ない分散剤を用いた比較例は流動性が著しく劣っており、圧縮強度が格段に低い。ポリオキシアルキレン基を有しない分散剤を用いたものは混練りができず、成形不能であった。
【００２４】
【表１】
【表２】
実施例２
表３に示す配合の材料を用い、バドルミキサーで練混ぜた組成物を円柱供試体(D10×H20cm)あるいは角柱供試体(10×10×40cm)に成形し、２０℃での水中養生２８日後の圧縮強度および曲げ強度を日本工業規格(JIS A 1108,1106)に準じて測定した。この結果を表３に示した。
なお、組成物を混練りする際には、先ず粒径５mm以下の材料に分散剤を含有する水を加えてミキサーで混合し、粒径５mm以上の材料(粗骨材)を有するものは、この混練物に粗骨材を加えて練り混ぜた。また、分散剤としてはオキシエチレンの付加モル数６８のポリオキシアルキレン化合物と無水マレイン酸とアリルスルホン酸の共重合物を用い、その添加量を表３に示した。セメントは低熱ポルトランドセメントを用い、５mm以下の骨材としてシリカフューム、珪石粉末、珪砂粉石を用い、粗骨材として硬質砂岩砕石(吸水率0.3％、最大寸法20mm、ＦＭ=6.7)を用いた。
【００２７】
【表３】
表３の比較例に示すように、粒径５mm以上の粗骨材を入れたものは極端に圧縮強度ならびに曲げ強度が減少した。また、単位水量が体積比で２５％を上回っても強度は大きく低下した。セメントに対する骨材の重量比が４を越えると組成物が流動性を失い成形できなかった。一方、本発明の実施例(No.2-1〜No.2-5)はいずれも高い圧縮強度および曲げ強度を有している。
【００２９】
実施例３
各材料の配合比が、セメント(Ｃ)３５体積部に、骨材としてシリカフューム１０体積部、珪石粉末１５体積部、豊浦珪砂２０体積部を加え、これに表１に示す分散剤を含む水２０体積部を添加してセメント組成物とした。このセメント組成物１リットルをホバートミキサで１０分間練り混ぜ、その流動性をガラス板上に置いたリング(D25mm？20mm)に流し込み、リングを引き上げ、丸く広がった組成物の長径と短径を測定し平均値をフロー値として表し、流動性を評価した。また、この組成物を用い角柱の供試体(2・？3cm)を成形し、翌日脱型した直後、２０℃の水中養生を２８日、８０℃の水中養生を３日行った後に圧縮強度を測定した。この結果を表４に示した。
なお、セメントの種類を中庸(Ｍ)、白色(Ｗ)、普通(Ｎ)と変えて同様の試験を行った。また、分散剤としてはオキシエチレンの付加モル数６８のポリオキシアルキレン化合物と無水マレイン酸とアリルスルホン酸の共重合物を用い、その添加量は、セメント１００重量部に対し１重量部とした。さらに、可溶性カルシウム塩として亜硝酸カルシウムまたはチオシアン酸カルシウムを表４に示す量加えた。
【００３０】
表４に示すように、可溶性カルシウム塩を添加したものは、初期強度の増進と流動性の向上が見られ、かつ、また、長期の強度の低下も見られず、高強度のセメント組成物を得る上で効果的である。
【００３１】
【表４】
BACKGROUND OF THE INVENTION
The present invention relates to a high-strength cementitious composition excellent in fluidity, and more particularly to a cementitious composition that has high fluidity and can be easily molded and has a hardened body with high strength.
[0002]
[Prior art]
Concrete is a representative cementitious composition. Concrete contains about 70% of aggregate in volume ratio in order to increase economic efficiency and to prevent cracking by suppressing shrinkage due to drying. As this aggregate, coarse aggregate having an average particle diameter of 5 mm or more and fine aggregate having an average particle diameter smaller than this are used. The purpose of using coarse aggregate is to increase the filling rate of the material so that the fluidity required for molding can be obtained with a small amount of water. If the amount of water is reduced, the water cement ratio becomes relatively small, which is advantageous in increasing the strength of the cement paste portion.
[0003]
On the other hand, using coarse aggregate with a large particle size means that the homogeneity of the hardened body is different between the coarse aggregate and the matrix, so the coarse aggregate and other matrix are not compatible and the interface is likely to break. Become. For this reason, the use of coarse aggregate is also a drawback in increasing the strength of the cured body. For example, when it is intended to obtain a high strength cured product having a compressive strength of 150 N / mm 2 or more, or when it is intended to increase the bending strength, it is not preferable to use coarse aggregate. On the other hand, if the particle size of the aggregate is reduced in order to homogenize the structure of the hardened body, the amount of water for obtaining fluidity necessary for molding increases, which is also not preferable for increasing the strength. Therefore, a dispersant is used in order to achieve both fluidity and a low amount of water, but the effect of the conventional one is insufficient.
[0004]
[Problem to be Solved by the Invention]
As described above, the conventional cementitious composition has insufficient flowability and strength after curing. An object of this invention is to provide the cementitious composition which solved such a conventional problem.
[0005]
[Means for solving the problems]
That is, the present invention is (1) a composition mainly composed of cement and aggregate with a dispersant and water added, wherein the aggregate is a granular material having a particle size of 5 mm or less and containing silica fume. Yes, the amount of water added is 25% or less by volume, the dispersant is the general formula-(ΑO) n-R (AO is an oxyalkylene group having 2 to 12 carbon atoms, R is hydrogen or a hydrocarbon group having 2 to 12 carbon atoms) , (AO) n has a molecular structure represented by n is a polyoxyalkylene group having an average addition mole number of 50 or more of oxyalkylene groups), and the amount of water added is 10 by volume with respect to the total volume of all materials. ~ 25%, aggregate / cement (weight ratio) is 0.5-4, the amount of dispersing agent is 0.1-5% by weight with respect to aggregate and cement having a particle size of 75 μm or less, and hardening after cementitious set, characterized by expressing a 150 N / mm 2 or more compression strength On things.
[0006]
The cementitious composition of the present invention is (2) using a dispersant having a carboxyl group and / or a sulfone group together with a polyoxyalkylene group, and (3) the polyoxyalkylene group is 50% by weight or more in the molecule. (4) The aggregate is 40 parts by weight or less of particles having a particle size of less than 1 μm, 200 parts by weight or less of particles having a particle size of 1 to 75 μm, and a particle size of 75 to 5 mm with respect to 100 parts by weight of cement. Particles having a particle size of 400 parts by weight or less.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail together with examples. The cementitious composition of the present invention is a composition obtained by adding a dispersant and water to a cement and aggregate composition, and limits the particle size of the aggregate to a range below the fine aggregate as much as possible. And further adding a dispersant having a specific molecular structure to achieve excellent fluidity and material strength while reducing the amount of added water. Specifically, the aggregate is a granular material having a particle size of 5 mm or less, the amount of added water is limited to 25% or less by volume, and the dispersant is represented by the general formula-(AO) n-R (AO has 2 carbon atoms). To 12 oxyalkylene groups, R is hydrogen or a hydrocarbon group having 2 to 12 carbon atoms, (ΑO) n is a polyoxyalkylene group in which n is an average added mole number of 50 or more of oxyalkylene groups) It is what uses what has.
[0008]
( I ) Cement The type of cement used in the present invention is not limited. Portland cement, mixed cement, fast-curing cement or the like can be used. As the Portland cement, normally, moderately hot, early strength, very early strength, sulfate resistant, low heat, and white Portland cement can be used. Moderate heat, sulfate-resistant, and low heat Portland cements are preferred because they contain a small amount of aluminate mineral (C 3 Α) and have good fluidity. The mixed cement includes fly ash cement, blast furnace cement and silica cement, any of which can be used in the present invention. The mixed cement is preferable in terms of enhancing the fluidity because the Portland cement content in the composition is relatively less than other cements. Fast-hardening cements harden in a short time and lose fluidity quickly, but are effective when strength development is required early.
[0009]
(II) Aggregate The aggregate used in the present invention has a particle size of 5 mm or less. In the present invention, the particle size of 5 mm or less means that the remaining amount on the 5 mm sieve is less than 10% in the aggregate sieving test defined in Japanese Industrial Standard (JIS A 1102-1989). Preferably, the remaining amount on a 1.2 mm sieve is less than 10%.
[0010]
The aggregate of the present invention preferably has the following particle size distribution in order to increase fluidity and increase the filling degree and strength of the composition. That is, with respect to 100 parts by weight of cement, 1 [mu] m or less of particles of 40 parts by weight or less, particles of lμm~75μm 200 parts by weight, 75 [mu] m or more particles is not more than 400 parts by weight, aggregate and ([rho) A cement (C) having a weight ratio (Ρ / C) of 0.5 to 4 is preferred.
[0011]
The material of the aggregate is not limited. A siliceous aggregate that reacts with cement and pozzolanic is preferable for obtaining high strength. In particular, those having a small particle size are preferably those having a high siliceous content in terms of pozzolanic reaction. Examples of siliceous aggregates include silica fume, silica sol, precipitated silica, fly ash, slag, volcanic ash, quartz sand, rock powder, river sand, mountain sand, land sand, sea sand, and crushed sand. In order to adjust the balance between silica and lime, it is also useful to use fine limestone powder or crushed limestone sand.
[0012]
(III) Dispersant The dispersant used in the present invention contains, in its molecule, a general formula-(AO) n-R (AO is an oxyalkylene group having 2 to 12 carbon atoms, R is hydrogen or carbon number). 2 to 12 hydrocarbon groups (AO) n has a molecular structure represented by (n is a polyoxyalkylene group having an average addition mole number of oxyalkylene group of 50 or more). The polyoxyalkylene group contained in the molecule of the dispersant repels the material particles of the composition due to its steric hindrance effect, and improves dispersibility. In particular, it is effective in a low water powder ratio system that is difficult to disperse with naphthalenesulfonic acid.
[0013]
In order to repel material particles by such a steric hindrance effect, the average number of added moles of oxyalkylene group (n in the general formula) is important. The larger the average added mole number n, the greater the effect. Specifically, n = 50 or more is good. The upper limit of the average added mole number n is not particularly limited, but 200 or less would be appropriate from the viewpoint of production economy. The dispersant may contain two or more kinds of oxyalkylene groups having different average added mole numbers n in the molecule. Among the polyoxyalkylene groups, the polyoxyethylene group is economical in production, but may be a polyoxypropylene group or the like. Moreover, you may have 2 or more types of oxyalkylene groups on the same chain.
[0014]
Furthermore, the dispersant used in the present invention preferably has a carboxyl group and / or a sulfone group together with polyoxyethylene so as to be adsorbed on cement and enhance the effect. As a specific example, (i) a copolymer comprising an acrylic monomer such as acrylate, methacrylate or a derivative thereof, and a compound having a polyoxyalkylene group copolymerizable with these monomers as essential components (Ii) a copolymer of maleic anhydride and a compound having a polyoxyalkylene copolymerizable with maleic anhydride, (iii) a component of a sulfonic acid compound such as allylsulfonic acid in (i) (ii) above And (iV) a compound having a polyoxyalkylene group capable of formaldehyde co-condensation with an aromatic compound and a formaldehyde co-condensate. These copolymers and cocondensates may be in the form of salts.
[0015]
Cement dispersants containing these compounds having polyoxyalkylene groups (hereinafter referred to as polyoxyalkylene compounds) as essential components are, for example, acrylic copolymers based on JP-A-58-74552 and JP-A-01. -226757, JP-A-6-206750, JP-A-07-109156, JP-A-07-126053, JP-A-08-12396, JP-A-09-27850, etc. Copolymers are described in JP-A 63-285140, JP-A 05-310458, JP-A 09-255740, and the like. Examples of formaldehyde cocondensates with aromatic compounds are described in JP-A 06-340459 and JP-A 07-109158. However, all of these are only those components, and no investigation has been made on the addition mole number n for the purpose of increasing the strength of the cementitious composition. Moreover, the strengths of the compositions described therein are much lower than those of the present invention. For example, even in JP-A-6-206750 for the purpose of providing high-strength cement composition, the best strength shown in the examples are mere 135N / mm 2, 150N / mm 2 , such as in the present invention It does not provide a level of high strength cement composition.
[0016]
In the dispersant used in the present invention, the content of polyoxyalkylene groups in the molecule is suitably 50% by weight or more. If it is less than 50% by weight, the particle dispersion effect due to the steric hindrance effect due to the polyoxyalkylene group cannot be sufficiently obtained, and the fluidity of the cementitious composition becomes insufficient.
[0017]
The amount of the dispersant added is suitably 0.1 to 5% by weight with respect to the aggregate and cement having a particle size of 75 μm or less. Aggregates having a particle size of 75 μm or less reduce the fluidity of the composition, and therefore the fluidity is prevented from being lowered by the dispersant. If the addition amount of the dispersing agent is less than the above range, the fluidity of the cementitious composition is significantly low, and if the addition amount is more than the above range, the strength development of the cementitious composition is hindered.
[0018]
The cement-based composition of the present invention can promote the development of strength by adding a soluble calcium salt. Examples of soluble calcium salts that are readily available and easy to use include calcium nitrite, calcium nitrate, calcium formate, calcium thiocyanate, and calcium chloride. The addition amount of these is suitably 0.1 to 5% by weight.
[0019]
The amount of water added to the cementitious composition of the present invention is 25% or less by volume with respect to the total volume of all materials, and preferably 10% to 25%. In particular, in order to obtain high strength, 20% or less is preferable. If the amount of water is less than 10%, the fluidity of the composition is lost. Moreover, when the amount of added water exceeds 25%, the strength decreases.
[0020]
When curing the cementitious composition of the present invention, no special treatment is required for curing. In addition, when it is set at a temperature of 45 ° C. or more for 3 hours or more, a hardened body with higher strength can be obtained.
[0021]
【The invention's effect】
The cementitious composition of the present invention can obtain a compressive strength of 150 N / mm 2 or more after curing. In this way, it is very dense and the strength of the cured body is high, and it has excellent durability, so it can be widely used in various fields such as civil engineering, construction, and machinery, and it can be further durable by using it instead of conventional concrete. Can increase the sex. Also, it can be used as a substitute for resin or steel.
Furthermore, since the cementitious composition of the present invention is excellent in fluidity, it has good workability, can be poured, and can be easily constructed using a pump.
[0022]
【Example】
Hereinafter, the present invention will be specifically described by way of examples.
Example 1
The blending ratio of each material was 10 parts by volume of silica fume, 15 parts by volume of silica powder, and 20 parts by volume of Toyoura quartz sand as aggregates in 35 parts by volume of moderately hot Portland cement, and water 20 containing the dispersant shown in Table 1 was added thereto. A volume part was added to obtain a cement composition. 1 liter of this cement composition is kneaded with a Hobart mixer for 10 minutes, poured into a ring (D25mm x H20mm) placed on a glass plate, and the major axis and minor axis of the composition spread round by measuring the ring are measured. The average value was expressed as a flow value, and the fluidity was evaluated. In addition, a prismatic specimen (2 × 2 × H3 cm) was formed from this composition, and after 20 days of water curing at 20 ° C. and 3 days of water curing at 80 ° C., the compressive strength was set to Japanese Industrial Standard ( Measured according to JIS A 1108). The results are shown in Table 1.
The aggregate is composed of 23 parts by weight of 1 μm or less particles, 39 parts by weight of 1 to 75 μm particles, and 50 parts by weight of 75 μm to 5 mm particles with respect to 100 parts by weight of cement. The amount of the dispersant added is 1 part by weight per 100 parts by weight of cement. The components of the dispersant shown in Table 1 are as shown in Table 2.
[0023]
As shown in Table 1, the greater the number of moles of oxyethylene added in the dispersant, the higher the dispersibility of the composition. Due to this action, a uniform molded body with few bubbles is obtained, so that the compression strength of the molded body is improved.
Also, those having a carboxyl group and a sulfone group at the same time have high initial fluidity and can reduce the change in fluidity over time. On the other hand, the comparative example using the dispersing agent having a smaller number of added moles of oxyethylene than the present invention is remarkably inferior in fluidity and has a remarkably low compressive strength. Those using a dispersant having no polyoxyalkylene group could not be kneaded and could not be molded.
[0024]
[Table 1]
[Table 2]
Example 2
Using the ingredients shown in Table 3, the composition kneaded with a paddle mixer was molded into a cylindrical specimen (D10 x H20 cm) or a prismatic specimen (10 x 10 x 40 cm), and after curing in water at 20 ° C for 28 days Compressive strength and bending strength were measured according to Japanese Industrial Standards (JIS A 1108, 1106). The results are shown in Table 3.
When the composition is kneaded, first, water containing a dispersant is added to a material having a particle size of 5 mm or less and mixed with a mixer, and a material having a particle size of 5 mm or more (coarse aggregate) Coarse aggregate was added to this kneaded product and kneaded. Further, as the dispersant, a polyoxyalkylene compound having an addition mole number of 68 of oxyethylene, a copolymer of maleic anhydride and allyl sulfonic acid was used, and the addition amount is shown in Table 3. As the cement, low heat Portland cement was used, silica fume, silica powder and silica sand powder were used as aggregates of 5 mm or less, and hard sandstone crushed stone (water absorption rate 0.3%, maximum dimension 20 mm, FM = 6.7) was used as coarse aggregate.
[0027]
[Table 3]
As shown in the comparative examples in Table 3, the compressive strength and bending strength were extremely reduced when the coarse aggregate having a particle size of 5 mm or more was added. Moreover, even if the unit amount of water exceeded 25% by volume, the strength was greatly reduced. When the weight ratio of aggregate to cement exceeded 4, the composition lost fluidity and could not be molded. On the other hand, the examples (No. 2-1 to No. 2-5) of the present invention all have high compressive strength and bending strength.
[0029]
Example 3
The mixing ratio of each material is 35 parts by volume of cement (C), 10 parts by volume of silica fume, 15 parts by volume of silica powder, and 20 parts by volume of Toyoura quartz sand as aggregates, and water 20 containing the dispersant shown in Table 1 is added thereto. A volume part was added to obtain a cement composition. Mix 1 liter of this cement composition with a Hobart mixer for 10 minutes, pour the fluidity into a ring (D25mm? 20mm) placed on a glass plate, lift the ring, and measure the long and short diameters of the composition that has spread roundly. The average value was expressed as a flow value, and the fluidity was evaluated. In addition, a prismatic specimen (2. 3 cm) was formed using this composition, and immediately after demolding the next day, 20 ° C water curing was performed for 28 days, and 80 ° C water curing was performed for 3 days. It was measured. The results are shown in Table 4.
The same test was performed by changing the type of cement to medium (M), white (W), or normal (N). As the dispersant, a polyoxyalkylene compound having an addition mole number of 68 of oxyethylene, a copolymer of maleic anhydride and allyl sulfonic acid was used, and the addition amount was 1 part by weight with respect to 100 parts by weight of cement. Furthermore, calcium nitrite or calcium thiocyanate was added as a soluble calcium salt in the amount shown in Table 4.
[0030]
As shown in Table 4, when the soluble calcium salt was added, the initial strength was increased and the fluidity was improved, and the long-term strength was not decreased. It is effective in obtaining.
[0031]
[Table 4]
Claims (4)
骨材が粒径５mm以下の粉粒体でシリカフュームを含有するものであり、分散剤が一般式−(ＡＯ)ｎ−Ｒ（ＡＯは炭素数２から１２のオキシアルキレン基、Ｒは水素あるいは炭素数２から１２の炭化水素基、(ＡＯ)ｎはｎがオキシアルキレン基の平均付加モル数５０以上のポリオキシアルキレン基）で表される分子構造を有するものであり、
添加水量が全材料の合計体積に対し体積比で１０〜２５％、骨材／セメント(重量比)が０.５〜４で、分散剤の添加量が粒径７５μm以下の骨材およびセメントに対して０.１〜５重量％であり、かつ硬化後に１５０N/mm2以上の圧縮強度を発現することを特徴とするセメント系組成物。A cement-based composition in which a dispersant and water are added to cement and aggregate,
The aggregate is a powder having a particle size of 5 mm or less and containing silica fume, the dispersant is a general formula-(AO) n-R (AO is an oxyalkylene group having 2 to 12 carbon atoms, R is hydrogen or carbon A hydrocarbon group of 2 to 12, (AO) n has a molecular structure represented by n is a polyoxyalkylene group having an average addition mole number of 50 or more of oxyalkylene groups)
The amount of added water is 10-25% by volume with respect to the total volume of all materials, the aggregate / cement (weight ratio) is 0.5-4, and the added amount of the dispersant is an aggregate and cement having a particle size of 75 μm or less. A cement-based composition characterized by being 0.1 to 5% by weight and exhibiting a compressive strength of 150 N / mm 2 or more after curing.
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