JP2005047738A - Expansive concrete having low temperature dependency - Google Patents

Expansive concrete having low temperature dependency Download PDF

Info

Publication number
JP2005047738A
JP2005047738A JP2003205029A JP2003205029A JP2005047738A JP 2005047738 A JP2005047738 A JP 2005047738A JP 2003205029 A JP2003205029 A JP 2003205029A JP 2003205029 A JP2003205029 A JP 2003205029A JP 2005047738 A JP2005047738 A JP 2005047738A
Authority
JP
Japan
Prior art keywords
concrete
expansion
expansive
component
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2003205029A
Other languages
Japanese (ja)
Inventor
Shinya Satake
紳也 佐竹
Takashi Sakuma
隆司 佐久間
Mitsuru Tanimura
充 谷村
Yuji Mitani
裕二 三谷
Original Assignee
Taiheiyo Material Kk
太平洋マテリアル株式会社
Taiheiyo Cement Corp
太平洋セメント株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Taiheiyo Material Kk, 太平洋マテリアル株式会社, Taiheiyo Cement Corp, 太平洋セメント株式会社 filed Critical Taiheiyo Material Kk
Priority to JP2003205029A priority Critical patent/JP2005047738A/en
Publication of JP2005047738A publication Critical patent/JP2005047738A/en
Pending legal-status Critical Current

Links

Images

Abstract

<P>PROBLEM TO BE SOLVED: To provide expansive concrete having low temperature dependency. <P>SOLUTION: The expansive concrete in which an expensive component is blended has ≤33% temperature-dependent variation of restrained expansion distortion in a condition of steel ratio in the stabilized period after curing of ≤1.8 and 10-70°C. In the expansive concrete, for example, an expansive clinker mineral, in which alite, anhydrous gypsum and free quick lime constitute product phases of the expansive component, where the content of anhydrous gypsum is 0.5-10 wt.%, the content of free quick lime is 65-80 wt.% and 15-60 vol.% of free quick lime is included into the alite crystal, is used as a main component. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【0001】
【発明の属する技術分野】
本発明は、コンクリート打設後のコンクリート内部温度が上昇しても膨張量が安定な温度依存性の低い膨張性コンクリートに関する。
【0002】
【従来の技術】
部材あるいは構造物の寸法が大きい場合や単位セメント量が多いコンクリートの場合、セメントの水和発熱に起因するひび割れが発生しやすい。このようなコンクリートはマスコンクリートと定義されており、有害なひび割れが発生しない対策が必要とされている。温度ひび割れ対策としては、パイプクーリングでコンクリートの温度上昇を小さくする方策や、リフト高さを低くすることで内部拘束度を小さくして発生する応力を小さくする方策が知られている。しかし、パイプクーリングやリフト高を低くすることによる温度ひび割れ対策は、設置が繁雑になり工期が長くなる課題がある。
【0003】
また、膨張材のケミカルプレストレス導入により温度応力に対する抵抗力をつける方策も知られている。膨張材は比較的簡便に取り扱えることから温度ひび割れ対策として広く使用されている。膨張材の成分としては生石灰結晶を主体にするものと、カルシウムサルホアルミネート結晶を主体とするものが従来から知られている。また、この生石灰結晶の水和反応をセメント硬化に近い時期に調整するため、石灰類と他の無機物とを混合して焼成し、一部のCaO成分を遊離石灰として焼成クリンカー中に生成させたものも知られている(特許文献1〜3)。
【特許文献1】特公昭43−9448号公報
【特許文献2】特公昭62−61548号公報
【特許文献3】特開2001−316147号公報
【0004】
【発明が解決しようとする課題】
しかし、従来の石灰系膨張材を配合した膨張性コンクリートは温度依存性が大きく、マスコンクリートのような硬化時間の経過に伴って上昇するコンクリート温度が高いものにおいては、膨張材によるケミカルプレストレス導入が不安定となる欠点がある。
【0005】
本発明は、膨張性コンクリートにおける従来の上記問題を解決したものであって、特定成分からなる膨張成分を配合することにより、マスコンクリートのように硬化後の温度が高くなる場合であっても安定した膨張特性が得られ、安定した拘束応力(ケミカルプレストレス)を導入できる膨張性コンクリートを提供するものである。なお、本発明においては膨張性モルタルを含めて膨張性コンクリートと云う。
【0006】
【課題を解決するための手段】
本発明によれば以下の膨張性コンクリートが提供される。
(1)膨張成分を配合したコンクリートであって、硬化安定期の鉄筋比1.8以下かつ温度10〜70℃における拘束膨張歪みの温度による変動率が33%以下であることを特徴とする膨張性コンクリート。
(2)膨張成分を配合したコンクリートであって、膨張成分がアリット、無水石膏、遊離生石灰を生成相とし、無水石膏の含有量が0.5〜10重量%、遊離生石灰の含有量が65〜80重量%含有し、かつ、遊離生石灰の15〜60体積%がアリット結晶に内包する膨張性クリンカ鉱物を主成分とする上記(1)に記載する膨張性コンクリート。
(3)膨張成分の配合量が、コンクリート材料の合計量のうち5〜50kg/mである上記請求項(1)または(2)に記載する膨張性コンクリート。
【0007】
本発明の膨張性コンクリートは、高い強度発現性を有すると共にセメントとの差異が極めて小さい反応時間の経過を辿ることができる膨張成分を配合することによって、硬化安定期における拘束膨張歪みの温度による変動率を33%以下に抑制した温度依存性の極めて低いコンクリートである。従って、マスコンクリートに使用した場合でも安定した膨張量が得られると共に安定した拘束応力を導入することができる。この結果、ひび割れの発生を格段に低減することができる。
【0008】
【発明の実施の形態】
以下、本発明を実施例に基づいて具体的に説明する。
本発明の膨張性コンクリートは、膨張成分を配合したコンクリートであって、硬化安定期の鉄筋比1.8以下かつ温度10〜70℃における拘束膨張歪みの温度による変動率が33%以下であることを特徴とするものである。
【0009】
ここで、(イ)硬化安定期とは、内部にプレストレスト用の鉄筋を設けたコンクリートにおいて、拘束応力や拘束膨張歪みが急激に増加する硬化初期を経過した後を云い、具体的には例えば材齢2日後である。
また、(ロ)拘束膨張歪みの温度による変動率とは、膨張性コンクリートを常温で硬化させたときの硬化安定期の拘束膨張歪みAoと、コンクリート硬化によって上昇した温度域で硬化させたときの硬化安定期の拘束膨張歪みAhとの比を云う。具体的には例えば、膨張性コンクリートを20℃で硬化させたときの硬化安定期の拘束膨張歪みA20と、70℃までの所望の温度T℃で硬化させたときの硬化安定期の拘束膨張歪みAとの比〔A/A20×100(%)〕を云う。
【0010】
本発明の膨張性コンクリートは硬化安定期の鉄筋比1.8以下かつ温度10〜70℃における拘束膨張歪みの温度による変動率が33%以下である。因みに、一例として、従来の膨張性コンクリートにおける拘束膨張歪みの温度による変動率は約34%以上である。このように、本発明の膨張性コンクリートは温度依然性が低いので、マスコンクリートに使用した場合でも安定した膨張量が得られ、かつ安定した拘束応力を導入することができる。従って、ひび割れの発生を格段に低減することができる。
【0011】
以上のような温度依存性の低い本発明の膨張性コンクリートは、例えば、アリット、無水石膏、遊離生石灰を生成相とし、無水石膏の含有量が0.5〜10重量%、遊離生石灰の含有量が65〜80重量%含有し、かつ、遊離生石灰の15〜60体積%がアリット結晶に内包する膨張性クリンカ鉱物を主成分とする膨張成分を含有するものである。
【0012】
上記膨張性クリンカー鉱物は、遊離生石灰、アリットおよび無水石膏が生成相として存在する。上記クリンカー鉱物の主たる膨張作用は遊離生石灰の水和によつてもたらされる。上記クリンカー鉱物中の遊離生石灰含有量は65〜80重量%が適当であり、70〜75重量%が好ましい。この量が65重量%未満ではモルタルやコンクリートの収縮を抑制する十分な膨張量が得られ難いので好ましくなく、また80重量%を超えると急激な膨張を示すので好ましくない.
【0013】
また、上記クリンカー鉱物中の遊離生石灰は一部の生石灰結晶粒がアリット結晶中に内包された状態が好ましい。このような状態にすることによつてセメントの水和反応との時期的整合性を的確に達成し易くなり、また発現する膨張量を仔細に調整できるため、モルタルやコンクリートの形状寸法安定性を図ることができる。遊離生石灰のうちアリット結晶中に内包される生石灰結晶粒の割合は、15〜60体積%が適当である。この量が15体積%より低いとモルタルやコンクリートの収縮抑制効果は見られるものの形状寸法安定性を十分に図り難く、また60体積%を超えると水和反応活性が低減し、膨張発現性が遅延するので好ましくない。
【0014】
また上記クリンカー鉱物中に生成する無水石膏(CaSO)は実質的に結晶質であり、通常はII型無水石膏の構造を示す。この無水石膏も水和によって膨張性を有するが、水和反応は生石灰よりも遅れて完結する。また生石灰およびアリットと共存生成することによって特に生石灰粒の粒成長を抑制する作用がある。
上記クリンカー鉱物中の無水石膏含有量は0.5〜10重量%が適当であり、3〜5重量%が好ましい。この量が0.5重量%未満では生石灰結晶粒が粒成長し易く、反応活性が低下するので好ましくなく、一方10重量%を超えると膨張発現性が過度に長期化するため好ましくない。
【0015】
また上記クリンカー鉱物中に生成するアリット(3CaO・Si0)は高い早期強度発現作用を有するほかに、生石灰の過度の水和活性を抑制する。上記クリンカー鉱物中のアリット含有量は、上記生石灰および無水石膏の残部あるいは残部の一部になる量が適当である。アリットは実質的に結晶構造で存在するが、生石灰結晶を内包することができる。
【0016】
上記クリンカー鉱物は、アリット、遊離生石灰および無水石膏以外の生成相の存在も、所望の性状に支障を及ぼさない範囲で許容される。許容可能性のある生成相としては、例えばアーウイン、フェライト等を挙げることができる他、製造原料等に由来する不可避不純物を含む相やこれがアリットや生石灰などの主生成相に固溶していても良い。
【0017】
上記クリンカー鉱物の製造方法は限定されず、また製造原料も限定されない。
一例を示すと、上記各生成相含有量になるように配合割合を調整した石灰石、石膏類および珪石からなる混合粉を、焼成炉で約1200〜1450℃に加熱した後、炉外急冷すれば得ることができる。ここで石膏類としては無水石膏、半水石膏、二水石膏の他、天然石膏や化学石膏などの何れであっても良い。また混合粉には例えば、炭酸カルシウム、化学成分でCaOやSiOを主体とする無機粉末、セメント焼成ダスト、粘土鉱物等を本膨張性クリンカー鉱物の性状に支障を及ぼさない範囲で加えても良い。
【0018】
また本発明において用いる膨張成分は、上記膨張性クリンカー鉱物の粉砕物、あるいはこれに石膏類を配合したものである。石膏類の配合量は、上記膨張性クリンカー鉱物100重量部に対して石膏類5〜100重量部が好ましい。この石膏類が5重量部未満では強度発現性が低下することがあるので好ましくなく、100重量部を超えると凝結遅延を起こしたり、膨張発現性の遅れから寸法安定性に欠くことがあるので好ましくない。使用する石膏類は無水石膏、半水石膏、二水石膏の他、天然石膏や化学石膏などの何れでも良い。なお、この膨張成分は上記以外の成分を所望の性状に支障を及ぼさない範囲で含有することができる。このような成分として、例えばフライアツシュやシリカフユーム等のボゾラン反応物質やセメントに配合使用できる混和材(剤)等を挙げることができる。
【0019】
本発明に係る膨張性コンクリートにおいて各成分の配合量等は以下の範囲が好ましい。
(イ)上記膨張成分の含有量は5〜50kg/mが好ましい。この量が5kg/m未満では膨張量が不足し、一方、50kg/mを超えると膨張過大になり、圧縮強度が低下する。
(ロ)単位セメント量は250〜600kg/mが好ましい。この量が250kg/m未満では膨張量が不足し、600kg/mを超えると膨張量不足する。
(ハ)単位水量は150〜200kg/mが好ましい。この量が150kg/m未満ではワーカビリティが悪化し、一方、200kg/mを超えると乾燥収縮が大きくなる。
(ニ)減水剤は減水剤/セメント比が0.1〜3.0重量部になる量が好ましい。
この量が0.1重量部未満ではワーカビリティが悪化し、一方、3.0重量部より多いと凝結遅延を招く。
(ホ)細骨材率は30〜50%が好ましい。30%未満および50%を超えるとワーカビリティが悪化する。
(ヘ)水セメント比は25〜65%が好ましい。25%未満ではワーカビリティが悪化し、65%を超えると圧縮強度不足を招き、また乾燥収縮も大きくなる。
【0020】
石膏は無水石膏、半水石膏、二水石膏の何れでもよい。セメントはポルトランドセメント(普通ポルトランドセメント、早強ポルトランドセメント、超早強ポルトランドセメント、中庸熱ポルトランドセメント、低熱ポルトランドセメント、耐硫酸塩ポルトランドセメント)、混合セメント(高炉セメント、フライアッシュセメント、シリカセメント)、特殊セメント(白色セメント、アルミナセメント、超速硬セメント、グラウト用セメント、油井セメント、低発熱セメント、エコセメントなど)を用いることができる。
【0021】
減水剤はAE剤(樹脂系、アルキルベンゼンスルホン酸系、高級アルコールエステル系など)、AE減水剤(ポリオール複合体、リグニンスルホン酸塩、オキシカルボン酸塩など)、高性能AE減水剤(ナフタレン系、ポリカルボン酸系、メラミン系、アミノスルホン酸系など)などの何れも用いることができる。また流動化剤を配合してもよい。細骨材として天然骨材(川砂、海砂、山砂)、人工骨材(砕砂、軽量骨材、重量骨材、スラグ骨材)の何れも用いることができる。また粗骨材として天然骨材(川砂利、海砂利、山砂利)、人工骨材(砕石、軽量骨材、重量骨材、スラグ骨材)の何れも用いることができる。
【0022】
その他に、混和材(フライアッシュ、高炉スラグ微粉末、シリカフュ―ム、石灰石微粉末、炭カル)や、防錆剤、収縮低減剤、急結剤、硬化促進剤、凝結遅延剤、防水剤、増粘剤などを添加してもよい。
【0023】
【実施例】
以下、本発明の実施例および比較例を示す。
表1に示す材料を用い、表2の配合条件、および表3の配合量に従って膨張性コンクリートを調製し、表4の条件下で図1の断面に示す状態になるように内部鉄筋を設けて型枠に打ち込み、これを表5の条件に従って養生した。硬化後のコンクリートについて、材齢ごとの拘束膨張歪みと拘束応力の変化を測定した。この結果を図2および図3に示した。なお図中、■印と●印は本発明の実施例、□印と○印は従来の比較例である。
【0024】
拘束膨張歪みは図1に示すようにPC鋼棒中央切削部の対称面に貼付した自己温度補償型の歪みゲージによって測定した。また、鉄筋の拘束応力は、「コンクリートの自己収縮応力試験方法」(自己収縮研究委員会日本コンクリート工学協会)に従い、式σc=(Es×εs×As)/Ac〔ここで、σcはコンクリートの応力(N/mm)、Esは鋼材の弾性係数(N/mm)、Asは鋼材の中央部分断面積(N/mm)、Acはコンクリートの純断面積(N/mm)〕によって求めた。
【0025】
【表1】
【0026】
【表2】
【0027】
【表3】
【0028】
【表4】
【0029】
【表5】
【0030】
図2の拘束膨張歪みのグラフに示すように、拘束鋼材比(ie.鉄筋比)1.0の試験体において、CASを用いた従来の膨張性コンクリートでは、養生20℃で硬化したときの硬化安定期における拘束膨張歪みA220(図中□印)は224であり、養生50℃で硬化したときの硬化安定期における拘束膨張歪みA250(図中○印)は147であり、この温度による変動率〔A250/A220×100(%)〕は約34%である。一方、成分調整した膨張成分を用いた本発明の膨張性コンクリートでは、養生20℃で硬化したときの硬化安定期における拘束膨張歪みA120(図中■印)は249であり、養生50℃で硬化したときの硬化安定期における拘束膨張歪みA150(図中●印)は230であって、この温度による変動率〔A150/A120×100(%)〕は約8%であり、比較例に比べて格段に低い。
【0031】
図3に示す拘束応力(N/mm)についても同様の結果が得られる。すなわち、CASを用いた従来の膨張性コンクリートでは、養生20℃で硬化したときの硬化安定期における拘束応力B220(図中□印)は0.448であり、養生50℃で硬化したときの硬化安定期における拘束応力B250(図中○印)は0.294であり、従って、温度による変動率〔A250/A220×100(%)〕は約34%である。一方、成分調整した膨張成分を用いた本発明の膨張性コンクリートでは、養生20℃で硬化したときの硬化安定期における拘束応力B120(図中■印)は0.498であり、養生50℃で硬化したときの硬化安定期における拘束応力B150(図中●印)は0.460であり、この温度による変動率〔A150/A120×100(%)〕は約8%である。
【0032】
【発明の効果】
本発明の膨張性コンクリートは、硬化安定期における拘束膨張歪みの温度による変動率を33%以下に抑制した温度依存性の極めて低いコンクリートである。従って、マスコンクリートに使用した場合でも安定した膨張量が得られ、かつ安定した拘束応力を導入することができる。この結果、ひび割れの発生を格段に低減することができる。
【図面の簡単な説明】
【図1】実施例におけるプレストレストコンクリートの型枠断面図
【図2】拘束膨張歪みの材齢の経過による変化を示すグラフ
【図3】拘束応力の材齢の経過による変化を示すグラフ
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to expansible concrete having a low temperature dependency, in which the amount of expansion is stable even when the concrete internal temperature rises after the concrete is placed.
[0002]
[Prior art]
When the size of the member or structure is large or the concrete has a large amount of unit cement, cracks due to the hydration heat of the cement are likely to occur. Such concrete is defined as mass concrete, and measures to prevent harmful cracks are required. As measures against temperature cracks, there are known a method for reducing the temperature rise of concrete by pipe cooling and a method for reducing the stress generated by reducing the internal restraint degree by reducing the lift height. However, countermeasures against temperature cracking by lowering pipe cooling and lift height have the problem that installation becomes complicated and the construction period becomes longer.
[0003]
There is also known a method of imparting resistance to temperature stress by introducing chemical prestress in the expansion material. Inflatable materials are widely used as a countermeasure against temperature cracks because they can be handled relatively easily. As components of the expansion material, those mainly composed of quick lime crystals and those mainly composed of calcium sulfoaluminate crystals are conventionally known. Moreover, in order to adjust the hydration reaction of this quicklime crystal | crystallization at the time near cement hardening, limes and another inorganic substance were mixed and baked, and some CaO components were produced | generated in the baking clinker as free lime. The thing is also known (patent documents 1 to 3).
[Patent Document 1] Japanese Patent Publication No. 43-9448 [Patent Document 2] Japanese Patent Publication No. 62-61548 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-316147
[Problems to be solved by the invention]
However, conventional concrete containing expansive lime-based expansive material has a large temperature dependence, and in the case of concrete with a high concrete temperature that rises with the lapse of curing time, such as mass concrete, chemical prestress is introduced by the expansive material. Has the disadvantage of becoming unstable.
[0005]
The present invention solves the above-mentioned conventional problems in expansible concrete, and is stable even when the temperature after curing becomes high like mass concrete by blending an expansive component consisting of a specific component. Thus, the present invention provides an expandable concrete that can obtain a stable expansion property and can introduce a stable restraint stress (chemical prestress). In addition, in this invention, it is called expansible concrete including expansible mortar.
[0006]
[Means for Solving the Problems]
According to the present invention, the following expansible concrete is provided.
(1) Concrete in which an expansion component is blended, wherein the rate of variation of the constrained expansion strain at a temperature of 10 to 70 ° C. at a temperature of 10 to 70 ° C. is 33% or less. Concrete.
(2) Concrete in which an expansion component is blended, the expansion component is alite, anhydrous gypsum, and free quick lime as a generated phase, the content of anhydrous gypsum is 0.5 to 10% by weight, and the content of free quick lime is 65 to 65%. The expansible concrete described in the above (1) containing 80% by weight and containing an expansive clinker mineral in which 15 to 60% by volume of free quicklime is encapsulated in an alite crystal.
(3) The expansive concrete described in the above (1) or (2), wherein the compounding amount of the expansive component is 5 to 50 kg / m 3 in the total amount of the concrete material.
[0007]
The expansive concrete of the present invention has a high strength development property, and by mixing an expansive component capable of following the passage of a reaction time with a very small difference from cement, fluctuation of the constrained expansion strain due to temperature in the curing stable period It is a concrete with extremely low temperature dependency with the rate suppressed to 33% or less. Therefore, even when used for mass concrete, a stable expansion amount can be obtained and a stable restraining stress can be introduced. As a result, the occurrence of cracks can be significantly reduced.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described based on examples.
The expansible concrete of the present invention is a concrete in which an expansive component is blended, and the rate of variation of the constrained expansile strain at a temperature of 10 to 70 ° C. at a temperature of 10 to 70 ° C. is 33% or less. It is characterized by.
[0009]
Here, (a) the curing stabilization period refers to the time after the initial stage of curing in which the restraint stress and the restraint expansion strain increase rapidly in concrete having prestressed reinforcing bars inside. 2 days after age.
In addition, (b) the rate of variation of the constrained expansion strain depending on the temperature is the constrained expansion strain Ao in the curing stability period when the expandable concrete is cured at room temperature and the temperature when cured in the temperature range increased by the concrete curing. This is the ratio to the constrained expansion strain Ah during the curing stabilization period. Specifically, for example, curing plateau constraining expansion when the curing plateau of restrained expansion strain A 20 when the expandable concrete cured at 20 ° C., and cured at the desired temperature T ° C. up to 70 ° C. This is the ratio [A T / A 20 × 100 (%)] to the strain AT .
[0010]
The expansible concrete of the present invention has a steel bar ratio of not more than 1.8 in the curing stability period and a rate of variation of the restrained expansion strain at a temperature of 10 to 70 ° C. is 33% or less. Incidentally, as an example, the variation rate of the constrained expansion strain with temperature in the conventional expansive concrete is about 34% or more. Thus, since the expansible concrete of the present invention has low temperature dependence, a stable expansion amount can be obtained even when used for mass concrete, and a stable restraining stress can be introduced. Therefore, the generation of cracks can be significantly reduced.
[0011]
The expandable concrete of the present invention having a low temperature dependency as described above has, for example, alite, anhydrous gypsum, and free quick lime as a production phase, and the content of anhydrous gypsum is 0.5 to 10% by weight, and the content of free quick lime. Is contained in an amount of 65 to 80% by weight, and 15 to 60% by volume of the free quicklime contains an expansion component mainly composed of an expandable clinker mineral encapsulated in an alite crystal.
[0012]
The expansive clinker mineral has free quicklime, alit and anhydrous gypsum as the product phase. The main swelling action of the clinker mineral is brought about by the hydration of free quicklime. The content of free quicklime in the clinker mineral is suitably 65 to 80% by weight, preferably 70 to 75% by weight. If this amount is less than 65% by weight, it is difficult to obtain a sufficient amount of expansion to suppress shrinkage of mortar or concrete, and if it exceeds 80% by weight, rapid expansion will occur, which is not preferable.
[0013]
Moreover, the free quick lime in the clinker mineral is preferably in a state in which some quick lime crystal grains are encapsulated in an alit crystal. In this state, it becomes easy to accurately achieve time consistency with the hydration reaction of cement, and the amount of expansion that can be expressed can be finely adjusted, so that the dimensional stability of mortar and concrete is improved. Can be planned. 15-60 volume% is suitable for the ratio of the quicklime crystal grain included in an alit crystal among free quicklime. If this amount is less than 15% by volume, the effect of suppressing shrinkage of mortar and concrete can be seen, but it is difficult to achieve sufficient shape and dimension stability. If it exceeds 60% by volume, the hydration reaction activity is reduced and the expansion is delayed. This is not preferable.
[0014]
Anhydrogypsum (CaSO 4 ) produced in the clinker mineral is substantially crystalline and usually shows the structure of type II anhydrite. Although this anhydrous gypsum also has swellability by hydration, the hydration reaction is completed later than quicklime. In addition, co-generation with quicklime and alit has the effect of suppressing the growth of quicklime grains.
The content of anhydrous gypsum in the clinker mineral is suitably 0.5 to 10% by weight, preferably 3 to 5% by weight. If this amount is less than 0.5% by weight, quick lime crystal grains tend to grow and the reaction activity is lowered, which is not preferable. On the other hand, if it exceeds 10% by weight, the expansion is excessively prolonged.
[0015]
The Alit generating the said clinker minerals (3CaO · Si0 2) in addition to having a high early strength development effect, suppresses excessive hydration activity of quicklime. The amount of the alit content in the clinker mineral is appropriate to be the balance of the quicklime and anhydrous gypsum or a part of the balance. The alit exists substantially in a crystalline structure, but can contain quicklime crystals.
[0016]
In the clinker mineral, the presence of a product phase other than alite, free quick lime, and anhydrous gypsum is allowed as long as the desired properties are not hindered. Examples of acceptable production phases include Irwin, ferrite and the like, as well as phases containing inevitable impurities derived from production raw materials and the like, and even if they are dissolved in the main production phase such as alit or quicklime. good.
[0017]
The method for producing the clinker mineral is not limited, and the production raw material is not limited.
For example, if the mixed powder composed of limestone, gypsum, and silica adjusted to the above-mentioned content of each generated phase is heated to about 1200 to 1450 ° C. in a firing furnace, and then rapidly cooled outside the furnace. Obtainable. Here, the gypsum may be anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, natural gypsum, chemical gypsum, or the like. In addition, for example, calcium carbonate, inorganic powders mainly composed of CaO and SiO 2 as chemical components, cement fired dust, clay minerals, and the like may be added to the mixed powder as long as the properties of the present expandable clinker mineral are not affected. .
[0018]
Further, the expansion component used in the present invention is a pulverized product of the above expandable clinker mineral, or a mixture of this with gypsum. As for the compounding quantity of gypsum, 5-100 weight part of gypsum is preferable with respect to 100 weight part of said expansible clinker minerals. If this gypsum is less than 5 parts by weight, the strength development may decrease, which is not preferable, and if it exceeds 100 parts by weight, setting delay may occur or dimensional stability may be lacking due to a delay in expansion development. Absent. The gypsum to be used may be anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, natural gypsum, chemical gypsum, or the like. In addition, this expansion | swelling component can contain a component other than the above in the range which does not interfere with a desired property. Examples of such components include bozolan reactants such as fly ash and silica fumes, and admixtures (agents) that can be used in cement.
[0019]
In the expandable concrete according to the present invention, the blending amount of each component is preferably in the following range.
(A) The content of the expansion component is preferably 5 to 50 kg / m 3 . If this amount is less than 5 kg / m 3 , the amount of expansion is insufficient. On the other hand, if it exceeds 50 kg / m 3 , the amount of expansion becomes excessive and the compressive strength decreases.
(B) The unit cement amount is preferably 250 to 600 kg / m 3 . If this amount is less than 250 kg / m 3 , the expansion amount is insufficient, and if it exceeds 600 kg / m 3 , the expansion amount is insufficient.
(C) The unit water amount is preferably 150 to 200 kg / m 3 . If this amount is less than 150 kg / m 3 , workability deteriorates, while if it exceeds 200 kg / m 3 , drying shrinkage increases.
(D) The amount of water reducing agent is preferably such that the water reducing agent / cement ratio is 0.1 to 3.0 parts by weight.
If this amount is less than 0.1 parts by weight, workability deteriorates, while if it exceeds 3.0 parts by weight, setting delay is caused.
(E) The fine aggregate ratio is preferably 30 to 50%. If it is less than 30% and exceeds 50%, workability deteriorates.
(F) The water cement ratio is preferably 25 to 65%. If it is less than 25%, the workability deteriorates. If it exceeds 65%, the compressive strength is insufficient, and the drying shrinkage also increases.
[0020]
The gypsum may be any of anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Cement is Portland cement (ordinary Portland cement, early strength Portland cement, super early strength Portland cement, medium heat Portland cement, low heat Portland cement, sulfate resistant Portland cement), mixed cement (blast furnace cement, fly ash cement, silica cement), Special cements (white cement, alumina cement, super fast cement, grout cement, oil well cement, low heat cement, eco cement, etc.) can be used.
[0021]
Water reducing agents include AE agents (resins, alkylbenzene sulfonic acids, higher alcohol esters, etc.), AE water reducing agents (polyol complexes, lignin sulfonates, oxycarboxylates, etc.), high performance AE water reducing agents (naphthalene, Any of polycarboxylic acid type, melamine type, aminosulfonic acid type and the like can be used. Moreover, you may mix | blend a fluidizing agent. As the fine aggregate, any of natural aggregate (river sand, sea sand, mountain sand) and artificial aggregate (crushed sand, lightweight aggregate, heavy aggregate, slag aggregate) can be used. As the coarse aggregate, any of natural aggregate (river gravel, sea gravel, mountain gravel) and artificial aggregate (crushed stone, lightweight aggregate, heavy aggregate, slag aggregate) can be used.
[0022]
In addition, admixtures (fly ash, blast furnace slag fine powder, silica fume, limestone fine powder, charcoal cal), rust inhibitor, shrinkage reducing agent, quick setting agent, hardening accelerator, setting retarder, waterproofing agent, A thickener or the like may be added.
[0023]
【Example】
Examples of the present invention and comparative examples are shown below.
Using the materials shown in Table 1, expandable concrete is prepared according to the blending conditions of Table 2 and the blending amounts of Table 3, and internal rebars are provided so as to be in the state shown in the cross section of FIG. It was driven into a mold and cured according to the conditions in Table 5. About the concrete after hardening, the change of restraint expansion distortion and restraint stress for every age was measured. The results are shown in FIG. 2 and FIG. In the figure, the ■ and ● marks are examples of the present invention, and the □ and ○ marks are conventional comparative examples.
[0024]
The constrained expansion strain was measured with a self-temperature compensated strain gauge affixed to the symmetry plane of the PC steel bar central cutting portion as shown in FIG. Further, the restraining stress of the reinforcing bar is in accordance with the “Self-Shrinkage Stress Testing Method for Concrete” (Self-Shrinkage Research Committee, Japan Concrete Engineering Association), and the formula σc = (Es × εs × As) / Ac (where σc is the concrete stress (N / mm 2), Es is the elastic modulus of the steel (N / mm 2), As the central cross sections of steel (N / mm 2), Ac net cross-sectional area of the concrete (N / mm 2)] Sought by.
[0025]
[Table 1]
[0026]
[Table 2]
[0027]
[Table 3]
[0028]
[Table 4]
[0029]
[Table 5]
[0030]
As shown in the restraint expansion strain graph of FIG. 2, in the test specimen having a restraint steel material ratio (ie. Steel bar ratio) of 1.0, the conventional expandable concrete using CAS is cured when cured at 20 ° C. Restrained expansion strain A2 20 (marked in the figure) in the stable period is 224, and restrained expansion strain A2 50 (marked in the figure in the figure) when cured at 50 ° C. is 147, depending on this temperature. The variation rate [A2 50 / A2 20 × 100 (%)] is about 34%. On the other hand, in the expansive concrete of the present invention using the expanded component whose components were adjusted, the restrained expansion strain A1 20 (marked by ■ in the figure) in the curing stable period when cured at 20 ° C. was 249, and at 50 ° C. The constrained expansion strain A1 50 (marked with ● in the figure) in the curing stable period when cured is 230, and the variation rate [A1 50 / A1 20 × 100 (%)] due to this temperature is about 8%. It is much lower than the example.
[0031]
Similar results are obtained for the restraining stress (N / mm 2 ) shown in FIG. That is, in the conventional expansible concrete using CAS, the restraint stress B2 20 (marked by □ in the figure) in the curing stability period when cured at 20 ° C. is 0.448, and when cured at 50 ° C. Restraint stress B2 50 (circle mark in the figure) in the curing stabilization period is 0.294, and therefore, the rate of variation [A2 50 / A2 20 × 100 (%)] due to temperature is about 34%. On the other hand, in the expansive concrete of the present invention using the expanded component whose components were adjusted, the restraining stress B1 20 (marked with ■ in the figure) in the curing stable period when cured at 20 ° C. was 0.498, and the curing was at 50 ° C. The restraint stress B1 50 (marked with ● in the figure) in the curing stabilization period when cured with is 0.460, and the variation rate [A1 50 / A1 20 × 100 (%)] due to this temperature is about 8%.
[0032]
【The invention's effect】
The expansive concrete of the present invention is a concrete with extremely low temperature dependency in which the variation rate of the constrained expansive strain in the curing stable period is suppressed to 33% or less. Therefore, even when used for mass concrete, a stable expansion amount can be obtained, and a stable restraining stress can be introduced. As a result, the occurrence of cracks can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a prestressed concrete formwork in an embodiment. FIG. 2 is a graph showing changes in restraint expansion strain over time. FIG. 3 is a graph showing changes in restraint stress over time.

Claims (3)

  1. 膨張成分を配合したコンクリートであって、硬化安定期の鉄筋比1.8以下かつ温度10〜70℃における拘束膨張歪みの温度による変動率が33%以下であることを特徴とする膨張性コンクリート。A concrete in which an expansion component is blended, characterized in that the rate of variation of the restrained expansion strain at a temperature of 10 to 70 ° C. at a temperature of 10 to 70 ° C. is 33% or less, in which the reinforcing steel ratio is 1.8 or less in the curing stability period.
  2. 膨張成分を配合したコンクリートであって、膨張成分がアリット、無水石膏、遊離生石灰を生成相とし、無水石膏の含有量が0.5〜10重量%、遊離生石灰の含有量が65〜80重量%含有し、かつ、遊離生石灰の15〜60体積%がアリット結晶に内包する膨張性クリンカ鉱物を主成分とする請求項1に記載する膨張性コンクリート。Concrete containing an expansion component, the expansion component is alite, anhydrous gypsum, and free quick lime as a production phase, the content of anhydrous gypsum is 0.5 to 10% by weight, the content of free quick lime is 65 to 80% by weight The expansible concrete according to claim 1, which contains an expansible clinker mineral contained as a main component and containing 15-60% by volume of free quicklime.
  3. 膨張成分の配合量が、コンクリート材料の合計量のうち5〜50kg/mである請求項1または2に記載する膨張性コンクリート。The expansive concrete according to claim 1 or 2, wherein the compounding amount of the expansive component is 5 to 50 kg / m 3 of the total amount of the concrete material.
JP2003205029A 2003-07-31 2003-07-31 Expansive concrete having low temperature dependency Pending JP2005047738A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2003205029A JP2005047738A (en) 2003-07-31 2003-07-31 Expansive concrete having low temperature dependency

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2003205029A JP2005047738A (en) 2003-07-31 2003-07-31 Expansive concrete having low temperature dependency

Publications (1)

Publication Number Publication Date
JP2005047738A true JP2005047738A (en) 2005-02-24

Family

ID=34263828

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2003205029A Pending JP2005047738A (en) 2003-07-31 2003-07-31 Expansive concrete having low temperature dependency

Country Status (1)

Country Link
JP (1) JP2005047738A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009001449A (en) * 2007-06-21 2009-01-08 Taiheiyo Material Kk Expansive composition
JP2009263164A (en) * 2008-04-25 2009-11-12 Denki Kagaku Kogyo Kk Cement admixture and cement composition for mass concrete
JP2013227172A (en) * 2012-04-26 2013-11-07 Taiheiyo Materials Corp Concrete
JP2017007924A (en) * 2015-06-26 2017-01-12 デンカ株式会社 Expansive material for precast concrete, manufacturing method therefor and manufacturing method of precast concrete

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002308661A (en) * 2001-01-30 2002-10-23 Taiheiyo Cement Corp High-performance concrete
JP2002326858A (en) * 2001-01-30 2002-11-12 Taiheiyo Cement Corp High performance concrete
JP2003063847A (en) * 2001-08-24 2003-03-05 Taiheiyo Material Kk Expansive material
JP2003192414A (en) * 2001-12-25 2003-07-09 Taiheiyo Cement Corp High performance concrete

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002308661A (en) * 2001-01-30 2002-10-23 Taiheiyo Cement Corp High-performance concrete
JP2002326858A (en) * 2001-01-30 2002-11-12 Taiheiyo Cement Corp High performance concrete
JP2003063847A (en) * 2001-08-24 2003-03-05 Taiheiyo Material Kk Expansive material
JP2003192414A (en) * 2001-12-25 2003-07-09 Taiheiyo Cement Corp High performance concrete

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009001449A (en) * 2007-06-21 2009-01-08 Taiheiyo Material Kk Expansive composition
JP2009263164A (en) * 2008-04-25 2009-11-12 Denki Kagaku Kogyo Kk Cement admixture and cement composition for mass concrete
JP2013227172A (en) * 2012-04-26 2013-11-07 Taiheiyo Materials Corp Concrete
JP2017007924A (en) * 2015-06-26 2017-01-12 デンカ株式会社 Expansive material for precast concrete, manufacturing method therefor and manufacturing method of precast concrete

Similar Documents

Publication Publication Date Title
JP4789466B2 (en) Rapidly setting cement composition
US8551241B2 (en) Fly ash based lightweight cementitious composition with high compressive strength and fast set
EP1532080A1 (en) Very fast setting cementitious composition
JP4494743B2 (en) Method for producing cement composition
JP5165873B2 (en) Reinforcement joint filling method using filler for reinforcing steel joints
US4964912A (en) Heat-curing cement composition, method of hardening same, and hardened body formed therefrom
JP5818579B2 (en) Neutralization suppression type early strong cement composition
JP2005047738A (en) Expansive concrete having low temperature dependency
KR100908675B1 (en) Concrete composition for revealing high early strength
JP3672518B2 (en) Cement admixture, cement composition and concrete using the same
JP2007055843A (en) Cement additive
JP4519985B2 (en) Super fast hard non-shrink grout material
JP2006131481A (en) Method for producing cement hardened body
JP5688069B2 (en) Cement composition, mortar or concrete using the same
JP2018131359A (en) Expanding material for an underwater anti-washout concrete, anti-washout underwater concrete composition, and hardened article thereof
JP2004210551A (en) Expansive clinker mineral and expansive composition containing the same
JP6974974B2 (en) Expansion concrete
JP2021160991A (en) Cement composition and method for producing cement composition
JP5863296B2 (en) Method for producing ultra-high-strength cement-based hardened body
JP5165436B2 (en) Concrete composition and hardened concrete
JP5403321B2 (en) Cement-based material
JP2021160986A (en) Cement composition and method for producing cement composition
JP2021160992A (en) Cement composition and method for producing cement composition
JP6084831B2 (en) Cement composition and concrete
JP2006282435A (en) High strength concrete

Legal Events

Date Code Title Description
A521 Written amendment

Effective date: 20050812

Free format text: JAPANESE INTERMEDIATE CODE: A523

A621 Written request for application examination

Effective date: 20060728

Free format text: JAPANESE INTERMEDIATE CODE: A621

RD04 Notification of resignation of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7424

Effective date: 20070629

RD04 Notification of resignation of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7424

Effective date: 20070816

RD02 Notification of acceptance of power of attorney

Effective date: 20070921

Free format text: JAPANESE INTERMEDIATE CODE: A7422

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A821

Effective date: 20070921

A977 Report on retrieval

Effective date: 20081202

Free format text: JAPANESE INTERMEDIATE CODE: A971007

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20090915

A02 Decision of refusal

Effective date: 20100316

Free format text: JAPANESE INTERMEDIATE CODE: A02