JP3549707B2 - Cement admixture, cement composition, and chemical prestressed concrete using the same - Google Patents
Cement admixture, cement composition, and chemical prestressed concrete using the same Download PDFInfo
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- JP3549707B2 JP3549707B2 JP15852997A JP15852997A JP3549707B2 JP 3549707 B2 JP3549707 B2 JP 3549707B2 JP 15852997 A JP15852997 A JP 15852997A JP 15852997 A JP15852997 A JP 15852997A JP 3549707 B2 JP3549707 B2 JP 3549707B2
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Classifications
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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
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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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
Description
【０００１】
【産業上の利用分野】
本発明は、主に、土木・建築業界において使用されるセメント混和材、セメント組成物、及びそれを用いたケミカルプレストレストコンクリートに関する。
【０００２】
【従来技術とその課題】
セメント混和材として使用される膨張物質は、乾燥収縮の補償やケミカルプレストレスの導入を目的として古くから数多く提案されている（特公昭４２−２１８４０号公報、特公昭４８−９４４８号公報、特公昭５３− １３６５０号公報、及び特公昭５３− ３１１７０号公報等）。
また、膨張物質は、その粒度を粗く調製することにより膨張力を増大させることが知られている（特公昭４２− ２１８４０号公報や特公昭５１−７１７１号公報など）。
そのため、膨張物質は、通常、セメントと同程度もしくはそれより粗く調製されている。
しかしながら、従来の膨張物質は、大きな膨張性を付与すればするほど、それを用いたセメント硬化体の空隙量が増加するので、機械的強度が低下するという宿命的な課題を有していた。
【０００３】
ここで、セメント硬化体とは、セメントペーストの硬化体、モルタルの硬化体、及びコンクリートの硬化体を総称するものである。
【０００４】
このような機械的強度発現性の低下は、例えば、土木・建築構造物においては、型枠の脱型が遅れることによって、工期が伸びたり、養生時間が長くなるために管理が困難になるばかりでなく、場合によっては構造物の耐久性に悪影響をおよぼすおそれもあった。
また、ヒューム管やボックスカルバートなどに代表されるコンクリート二次製品の製造においては、ケミカルプレストレスを導入する際、製品の外圧強度は膨張力を鉄筋によって拘束することにより増大することができるが、鉄筋の拘束がきかないコンクリートの端部は強度が弱く欠けやすいという課題があった。
コンクリート二次製品は、端部が少しなりとも欠けてしまえば、商品価値がなくなり、出荷することができないので端部の強度が弱く、欠けやすいことは大きな問題であった。
【０００５】
一方、本発明者は、膨張物質をブレーン比表面積値で４，０００ｃｍ２／ｇ以上になるよう微粉末化することによって無収縮性を付与できるグラウト材料を提案した（特開平 ７−２３７９５１号公報）。
通常、粉砕機によって粉砕した粉体の粒度は正規分布を有するので、このように微粉末化した粉末でも粗い粒子を含有している。
そのため、膨張性状は低く、強度発現性もそれほど向上しないという課題があった。
【０００６】
本発明者は種々努力を重ねた結果、特定の組成と、特定の最大粒径以下に粉砕した膨張物質を使用することにより、大きな膨張性を付与した場合にも、強度発現性が良好となり前述の課題が解決できる知見を得て本発明を完成するに至った。
【０００７】
【課題を解決するための手段】
即ち、本発明は、CaO 原料と CaSO４原料とを配合して熱処理してなり、 CaOと CaSO４とを含有する鉱物からなり、該鉱物中のCaSO４ が、 CaOと CaSO４の合計 100重量部中、10〜50重量部で、その最大粒径が100 μｍ以下である膨張物質を含有してなるセメント混和材であり、セメントと該セメント混和材とを含有してなるセメント組成物であり、該セメント組成物を配合してなるセメント混練物を、型枠内に打設充填し、養生してなるケミカルプレストレストコンクリートである。
【０００８】
以下、本発明をさらに詳しく説明する。
【０００９】
本発明のセメント混和材は特定の膨張物質を含有するものである。
本発明の膨張物質は、分級機能を付加した粉砕機によって粉砕することで、粒子群を特定範囲、例えば、最大粒径が １００μ以下の粒子の粒径に調製したものであり、従来技術の膨張物質とは大きく異っている。
【００１０】
膨張物質の原料は、純度やコストにより任意に選択されうるものであり、特に限定されるものではないが、例えば、ＣａＯ 原料として、石灰石や消石灰などのＣａＣＯ３ 質物質やＣａ（ＯＨ）２ 質物質などが、ＣａＳＯ４ 原料として、無水セッコウ、半水セッコウ、及び二水セッコウ等が挙げられる。
原料中に存在するＡｌ２Ｏ３ 、ＳｉＯ２、Ｆｅ２Ｏ３ 、ＣａＦ２、ＭｇＯ 、及びＴｉＯ２等の不純物は、本発明の目的を実質的に阻害しない範囲では特に限定されるものではない。
本発明におけるＣａＯ 原料やＣａＳＯ４ 原料の配合割合は、膨張物質中のＣａＳＯ４ が、ＣａＯ とＣａＳＯ４ の合計（以下膨張成分という）１００ 重量部中、１０〜５０重量部となるようにすることが必要であり、２０〜４０重量部となるようにすることが好ましい。ＣａＳＯ４ が１０重量部未満では強度発現性が低下する場合があり、５０重量部を越えると膨張性が低下する場合がある。
【００１１】
本発明では、原料の配合割合や不純物の含有量により、セッコウの脱硫酸分解温度が大きく変化するため、焼成温度は特に限定されるものではないが、通常、１，０００ 〜１，６００ ℃程度が好ましい。
原料の混合方法は特に限定されるものではなく、通常の方法が可能である。
【００１２】
膨張物質を製造する熱処理方法は特に限定されるものではなく、例えば、ロータリーキルンによる焼成や電炉による溶融などのいずれの方法も可能である。
【００１３】
膨張物質の粒径は、最大粒径が １００μｍ以下であり、７５μｍ以下が好ましく、５０μｍ以下がより好ましい。最大粒径が １００μｍを超えると、高膨張率を付与した場合のセメント硬化体の機械的強度の低下を抑制する本発明の効果が得られない場合がある。
本発明において、最大粒径は、実質上、その粒径以上の大きさの粒子が存在しないことを意味するものであり、具体的には、 １００μｍを越える粒子の存在が３重量％以下であり、通常、１重量％以下である。
粒子の最大粒径や分布は、粒度分布測定装置を用いることにより簡便に確認することが可能である。
【００１４】
本発明のセメント混和材の配合量は、使用する目的により異なるが、通常、セメント １００重量部に対して、３〜１２重量部が好ましく、５〜９重量部がより好ましい。３重量部未満では膨張性が充分ではなく、１２重量部を越えると異常膨張を起こす可能性がある。
【００１５】
ここでセメントとしては、普通、早強、超早強、及び中庸熱等の各種ポルトランドセメント、これらポルトランドセメントにポゾラン物質を混合した各種混合セメント、並びに、アルミナセメント等が挙げられるが、特に混合セメントにおいてその効果が顕著である。
【００１６】
本発明のセメント組成物を用いたセメント混練物を製造する際に、使用する混合装置としては、既存のいかなる撹拌装置も使用可能であり、例えば、傾胴ミキサー、オムニミキサー、Ｖ型ミキサー、ヘンシェルミキサー、及びナウターミキサー等が利用可能である。
また、混合は、それぞれの材料を施工時に混合してもよいし、あらかじめ一部を、あるいは全部を混合しておいても差し支えない。
【００１７】
本発明のセメント混練物の養生方法は特に限定されるものではなく、一般に行われる常温・常圧養生、蒸気養生、高温・高圧蒸気養生、及び加圧養生等のいずれの養生方法も適用可能である。
また、混練方法であるが、一般に用いられる方法でよく、特に限定されるものではない。
【００１８】
本発明では、さらに、砂や砂利などの骨材や、凝結調整剤、減水剤、高性能減水剤、ＡＥ剤、ＡＥ減水剤、高性能ＡＥ減水剤、増粘剤、セメント急硬材、防錆剤、防凍剤、水和熱抑制剤、高分子エマルジョン、ベントナイトやモンモリロナイトなどの粘土鉱物、ゼオライト、ハイドロタルサイト、及びハイドロカルマイト等のイオン交換体、硫酸アルミニウムや硫酸ナトリウムなどの硫酸塩、リン酸塩、並びに、ホウ酸等のうちの一種又は二種以上を本発明の目的を実質的に阻害しない範囲で併用することが可能である。
【００１９】
【実施例】
以下、実施例により本発明を詳細に説明する。
【００２０】
実施例１
ＣａＯ 原料とＣａＳＯ４ 原料を配合し、ロータリーキルンを用い、最高焼成温度１，４００ ℃で焼成してＣａＯ とＣａＳＯ４ の合計の膨張成分 １００重量部中の ＣａＳＯ４の量が異なる各種膨張物質のクリンカーを合成した。
合成したクリンカーをボールミルを用いて粉砕し、ブレーン値 ３，０００±２００ｃｍ２／ｇに調製し、さらに、開き目が５０μｍの篩で篩分けし最大粒径が５０μｍの膨張物質を調製した。
調製した膨張物質をセメント混和材とし、セメントαと該セメント混和材からなる結合材 １００重量部中、セメント混和材の配合量を９重量部とし、水／結合材比＝５０％、結合材／砂比＝１／３で、練り上がり温度２０±２℃のモルタルを作製し、材齢７日における膨張率と圧縮強度を測定した。結果を表１に示す。
なお、比較のために、膨張物質として市販の膨張材を使用して同様の方法により測定を行った。結果を表１に併記する。
【００２１】
＜使用材料＞
ＣａＯ 原料 ：石灰石粉末、新潟県青海鉱山産石灰石
ＣａＳＯ４ 原料：セッコウ、新秋田化成社製無水セッコウ
膨張物質Ａ：膨張成分１００ 重量部中のＣａＳＯ４ ０重量部
膨張物質Ｂ：膨張成分１００ 重量部中のＣａＳＯ４ １０重量部
膨張物質Ｃ：膨張成分１００ 重量部中のＣａＳＯ４ ２０重量部
膨張物質Ｄ：膨張成分１００ 重量部中のＣａＳＯ４ ３０重量部
膨張物質Ｅ：膨張成分１００ 重量部中のＣａＳＯ４ ４０重量部
膨張物質Ｆ：膨張成分１００ 重量部中のＣａＳＯ４ ５０重量部
膨張物質Ｇ：膨張成分１００ 重量部中のＣａＳＯ４ ６０重量部
膨張材ａ ：市販のカルシウムサルホアルミネート系膨張材
膨張材ｂ ：市販の生石灰系膨張材
セメントα：電気化学工業社製普通ポルトランドセメント
砂 ：標準砂、ＩＳＯ ６７９準拠
水 ：水道水
【００２２】
＜測定方法＞
膨張率 ：ＪＩＳ Ａ ６２０２ （Ｂ法） に準じて材齢７日の膨張率を測定
圧縮強度 ：ＪＩＳ Ａ １１０８に準じて材齢７日の圧縮強度を測定
【００２３】
【表１】
実施例２
膨張物質Ｄを使用し、結合材 １００重量部中、表２に示すセメント混和材の配合量を用いたこと以外は実施例１と同様に行った。結果を表２に併記する。
なお、比較のために、市販品である膨張材についても同様に行った。結果を表２に併記する。
【００２５】
【表２】
実施例３
セメントαの代わりにセメントβを用いたこと以外は実施例１と同様に行った。結果を表３に示す。
【００２７】
＜使用材料＞
セメントβ：電気化学工業社製高炉セメント（Ｂ種）
【００２８】
【表３】
実施例４
膨張物質Ｄを、表４に示す最大粒径となるように粉砕したこと以外は実施例１と同様に行った。結果を表４に併記する。
【００３０】
【表４】
実施例５
表５に示す最大粒径に調製した膨張物質をセメント混和材とし、セメント混和材を結合材 １００重量部中、９重量部配合し、各材料の単位量を、結合材４３０ｋｇ／ｍ３、細骨材６８５ｋｇ／ｍ３、粗骨材１，０９８ｋｇ／ｍ３、及び水１６７ｋｇ／ｍ３として、減水剤を結合材１００重量部に対して、１重量部配合し、水／結合材比＝４０％、細骨材率３９％のコンクリートを調製した。
型枠内に、主筋としてＰＣ鋼棒を、スパイラル筋としてＰＣ鋼線を用い、鉄筋比を ０．４％とした耐張芯材を配置し、調製したコンクリートを打設して、遠心力により、直径２０ｃｍ、長さ２５ｃｍ、肉厚４０ｍｍ±１ｍｍのコンクリート管を成形した。
６時間放置した後、昇温速度１５℃／ｈｒで６５℃まで昇温し、４時間保持した後、自然放冷し、材齢２４時間で脱型する蒸気養生を行い、その後、２０℃水中養生を行い、管端部の欠損状態を観察するとともに、プレストレス量を測定した。結果を表５に併記する。
【００３２】
＜使用材料＞
細骨材 ：新潟県姫川産川砂、５ｍｍ下
粗骨材 ：新潟県姫川産川砂利、Ｇｍａｘ ＝２５ｍｍ
【００３３】
＜測定方法＞
管端部の欠損状態：コンクリート管を高さ１ｍから３回落下させた時のコンクリート管端部の欠損状態を観察、○は欠損なし、×は欠損あり
プレストレス量：養生後、コンクリート管の外圧を負荷し、あらかじめスパイラル筋にはったストレインゲージで歪みを測定して材齢７日におけるプレストレス量を測定
【００３４】
【表５】
【発明の効果】
本発明のセメント混和材の使用により、膨張性と強度発現性が良好なセメント組成物とすることができ、これを用いたケミカルプレストレストコンクリートは外圧強度が大きく、コンクリート端部が欠けにくいなどの効果を奏する。[0001]
[Industrial applications]
The present invention relates to a cement admixture, a cement composition, and a chemical prestressed concrete using the same, mainly used in the civil engineering and construction industries.
[0002]
[Prior art and its problems]
Many expandable substances used as cement admixtures have long been proposed for the purpose of compensating for drying shrinkage and introducing chemical prestress (Japanese Patent Publication No. 42-21840, Japanese Patent Publication No. 48-9448, Japanese Patent Publication No. No. 53-13650 and Japanese Patent Publication No. 53-31170.
In addition, it is known that the swelling substance is increased in swelling force by adjusting its particle size to be coarse (JP-B-42-21840 and JP-B-51-7171).
For this reason, the intumescent material is usually prepared as coarse or coarser as cement.
However, the conventional expandable substance has a fatal problem that the greater the expandability, the greater the amount of voids in the cement-hardened body using the expandable substance, and the lower the mechanical strength.
[0003]
Here, the hardened cement is a generic term for hardened cement paste, hardened mortar, and hardened concrete.
[0004]
Such a decrease in mechanical strength manifestation, for example, in civil engineering and building structures, due to the delay of mold release, the construction period is extended, or the curing time becomes longer, so that it becomes difficult to manage. In addition, in some cases, the durability of the structure may be adversely affected.
In addition, in the production of concrete secondary products such as fume pipes and box culverts, when introducing chemical prestress, the external pressure strength of the product can be increased by restraining the expansion force with reinforcing steel, There was a problem that the end of the concrete where the reinforcing steel could not be restrained was weak and easily chipped.
Secondary concrete products, once lacking even the end is a little will, there is no commercial value, it is not possible to ship weakened the strength of the end, easy to missing it was a big problem.
[0005]
On the other hand, the present inventor has proposed a grout material capable of imparting non-shrinkage property by pulverizing an expansive substance so as to have a Blaine specific surface area value of 4,000 cm 2 / g or more (Japanese Patent Application Laid-Open No. 7-237951). ).
Usually, the particle size of the powder pulverized by the pulverizer has a normal distribution, so that even the finely pulverized powder contains coarse particles.
For this reason, there is a problem that the expandability is low and the strength expression is not so improved.
[0006]
The present inventor has made various efforts and, as a result of using a specific composition and an expandable substance pulverized to a specific maximum particle size or less, even when a large expandability is imparted, the strength developability becomes good, and The present invention has been completed based on the knowledge that can solve the above problem.
[0007]
[Means for Solving the Problems]
That is, the present invention is made by heat-treating by blending a CaO material and CaSO 4 material consists mineral containing a CaO and CaSO 4, is CaSO 4 in the mineral, total 100 weight of CaO and CaSO 4 Parts, 10 to 50 parts by weight, a cement admixture containing an expanding substance having a maximum particle size of 100 μm or less, and a cement composition containing cement and the cement admixture. A chemically prestressed concrete obtained by casting and kneading a cement kneaded product obtained by blending the cement composition into a mold and curing.
[0008]
Hereinafter, the present invention will be described in more detail.
[0009]
The cement admixture of the present invention contains a specific expanding substance.
The swelling substance of the present invention is obtained by crushing a particle group to a specific range, for example, particles having a maximum particle diameter of 100 μ or less by crushing with a crusher having a classification function. It is very different from substance.
[0010]
The raw material of the expanding substance can be arbitrarily selected depending on the purity and cost, and is not particularly limited. For example, as a CaO raw material, a CaCO 3 substance such as limestone or slaked lime or a Ca (OH) 2 substance Substances and the like, as the CaSO 4 raw material, anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum and the like.
Impurities such as Al 2 O 3 , SiO 2 , Fe 2 O 3 , CaF 2 , MgO and TiO 2 present in the raw material are not particularly limited as long as the objects of the present invention are not substantially impaired. .
The mixing ratio of the CaO material and CaSO 4 material in the present invention, CaSO 4 in the inflation material is the sum of CaO and CaSO 4 (hereinafter referred to as expansion component) in 100 parts by weight, to be 10 to 50 parts by weight Is required, and it is preferable that the amount be 20 to 40 parts by weight. If the content of CaSO 4 is less than 10 parts by weight, the strength developability may decrease, and if it exceeds 50 parts by weight, the expandability may decrease.
[0011]
In the present invention, since the desulfurization decomposition temperature of gypsum greatly changes depending on the mixing ratio of the raw materials and the content of impurities, the firing temperature is not particularly limited, but is usually about 1,000 to 1,600 ° C. Is preferred.
The method of mixing the raw materials is not particularly limited, and an ordinary method can be used.
[0012]
The heat treatment method for producing the expanding material is not particularly limited. For example, any method such as firing using a rotary kiln or melting using an electric furnace is possible.
[0013]
The maximum particle diameter of the expanding material is 100 μm or less, preferably 75 μm or less, and more preferably 50 μm or less. If the maximum particle size exceeds 100 μm, the effect of the present invention of suppressing a decrease in mechanical strength of a cured cement body when a high expansion coefficient is provided may not be obtained.
In the present invention, the maximum particle size means that substantially no particles having a size larger than the particle size are present. Specifically, the presence of particles exceeding 100 μm is 3% by weight or less. , Usually 1% by weight or less.
The maximum particle size and distribution of the particles can be easily confirmed by using a particle size distribution measuring device.
[0014]
The amount of the cement admixture of the present invention varies depending on the purpose of use, but is usually preferably 3 to 12 parts by weight, more preferably 5 to 9 parts by weight, per 100 parts by weight of cement. If it is less than 3 parts by weight, the expandability is not sufficient, and if it exceeds 12 parts by weight, abnormal expansion may occur.
[0015]
Here, examples of the cement include ordinary, high-strength, ultra-high-strength, and various types of Portland cements such as moderate heat, various mixed cements obtained by mixing a pozzolanic substance with these Portland cements, and alumina cements. The effect is remarkable.
[0016]
When producing a cement kneaded product using the cement composition of the present invention, any existing stirring device can be used as a mixing device, for example, a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer A mixer, a Nauta mixer and the like can be used.
In addition, for mixing, the respective materials may be mixed at the time of construction, or some or all of them may be mixed in advance.
[0017]
The method for curing the cement kneaded material of the present invention is not particularly limited, and any curing method such as ordinary temperature / normal pressure curing, steam curing, high temperature / high pressure steam curing, and pressure curing can be applied. is there.
The kneading method may be a commonly used method, and is not particularly limited.
[0018]
In the present invention, further, aggregates such as sand and gravel, a setting modifier, a water reducing agent, a high performance water reducing agent, an AE agent, an AE water reducing agent, a high performance AE water reducing agent, a thickener, a cement hardened material, Rust agents, antifreeze agents, hydration heat inhibitors, polymer emulsions, clay minerals such as bentonite and montmorillonite, zeolite, hydrotalcite, ion exchangers such as hydrocalumite, sulfates such as aluminum sulfate and sodium sulfate, One or more of phosphate, boric acid, and the like can be used in combination as long as the object of the present invention is not substantially inhibited.
[0019]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
[0020]
Example 1
A CaO raw material and a CaSO 4 raw material are blended, and baked at a maximum sintering temperature of 1,400 ° C. using a rotary kiln and a total expansion component of CaO 4 and CaSO 4 A clinker of various expanded materials having different amounts of CaSO 4 in 100 parts by weight. Was synthesized.
The synthesized clinker was pulverized using a ball mill, adjusted to a Blaine value of 3,000 ± 200 cm 2 / g, and further sieved with a sieve having an opening of 50 μm to prepare an expanded material having a maximum particle size of 50 μm.
The prepared intumescent material was used as a cement admixture, and the mixing amount of the cement admixture was 9 parts by weight in 100 parts by weight of the binder composed of cement α and the cement admixture. A mortar having a sand ratio of 1/3 and a kneading temperature of 20 ± 2 ° C. was prepared, and the expansion rate and compressive strength at the age of 7 days were measured. Table 1 shows the results.
For comparison, measurement was performed in the same manner using a commercially available expanding material as the expanding material. The results are also shown in Table 1.
[0021]
<Material used>
CaO raw material: limestone powder, limestone CaSO 4 from Aomi mine, Niigata Prefecture Raw material: gypsum, anhydrous gypsum manufactured by Shin-Akita Kasei Co., Ltd. Expanding substance A: 0 parts by weight of CaSO 4 in expanding part 100 parts by weight Expanding substance B: expanding part 100 parts by weight CaSO 4 10 parts by weight expandable material C in: CaSO 4 20 parts by weight expandable material D in the expansion component 100 parts by weight: CaSO 4 30 parts by weight expandable material in the expansion component 100 parts by weight E: in the expansion 100 parts by weight of component 40 parts by weight of CaSO 4 swelling substance F: 50 parts by weight of CaSO 4 in 100 parts by weight of swelling ingredient G: 60 parts by weight of CaSO 4 in 100 parts by weight of swelling ingredient Expanding material a: Commercial calcium sulfoaluminate-based expanding material Expanding material b: Commercial quicklime-based expanding material cement α: Ordinary Portland cement sand manufactured by Denki Kagaku Kogyo Co., Ltd .: Standard sand, ISO 679 standard Water: tap water [0022]
<Measurement method>
Expansion coefficient: Measure the expansion coefficient at 7 days of age according to JIS A 6202 (Method B) Compressive strength: Measure the compressive strength at 7 days of age according to JIS A 1108
[Table 1]
Example 2
The procedure was performed in the same manner as in Example 1 except that the intumescent substance D was used and the blending amount of the cement admixture shown in Table 2 was used in 100 parts by weight of the binder. The results are also shown in Table 2.
For comparison, the same procedure was performed for a commercially available expandable material. The results are also shown in Table 2.
[0025]
[Table 2]
Example 3
Example 1 was repeated except that cement β was used instead of cement α. Table 3 shows the results.
[0027]
<Material used>
Cement β: Blast furnace cement manufactured by Denki Kagaku Kogyo Co., Ltd. (Class B)
[0028]
[Table 3]
Example 4
The procedure was performed in the same manner as in Example 1 except that the intumescent substance D was pulverized to have the maximum particle size shown in Table 4. The results are shown in Table 4.
[0030]
[Table 4]
Example 5
The expandable substance adjusted to the maximum particle size shown in Table 5 was used as a cement admixture, and 9 parts by weight of the cement admixture was mixed with 100 parts by weight of the binder, and the unit amount of each material was 430 kg / m 3 of the binder, aggregate 685kg / m 3, coarse aggregate 1,098kg / m 3, and the water 167 kg / m 3, relative to the binder 100 parts by weight of water reducing agent was blended 1 part by weight, water / binder ratio = 40 % And a fine aggregate rate of 39% were prepared.
Using a PC steel rod as the main reinforcement and a PC steel wire as the spiral reinforcement, place a tension-resistant core material with a reinforcement ratio of 0.4% in the formwork, place the prepared concrete, and cast the concrete by centrifugal force. A concrete tube having a length of 20 cm, a length of 25 cm, and a thickness of 40 mm ± 1 mm was formed.
After standing for 6 hours, the temperature was raised to 65 ° C. at a rate of 15 ° C./hr, maintained for 4 hours, allowed to cool naturally, and subjected to steam curing to remove the mold after 24 hours of age, and then to water at 20 ° C. After curing, the state of the tube end defect was observed, and the amount of prestress was measured. The results are also shown in Table 5.
[0032]
<Material used>
Fine aggregate: river sand from Himekawa, Niigata prefecture, 5 mm coarse aggregate: gravel from Himekawa river, Niigata prefecture, Gmax = 25 mm
[0033]
<Measurement method>
Missing condition of pipe end: Observation of missing condition of concrete pipe end when concrete pipe was dropped three times from a height of 1 m, ○: no missing, ×: missing Prestress: After curing, concrete pipe An external pressure is applied, and the strain is measured with a strain gauge previously attached to a spiral streak to measure the prestress amount at the age of 7 days.
[Table 5]
【The invention's effect】
By using the cement admixture of the present invention, it is possible to obtain a cement composition having good expandability and strength development properties, and the chemical prestressed concrete using the same has a large external pressure strength, and the effect that the concrete end is hardly chipped is obtained. To play.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15852997A JP3549707B2 (en) | 1997-06-16 | 1997-06-16 | Cement admixture, cement composition, and chemical prestressed concrete using the same |
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| Application Number | Priority Date | Filing Date | Title |
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| JP15852997A JP3549707B2 (en) | 1997-06-16 | 1997-06-16 | Cement admixture, cement composition, and chemical prestressed concrete using the same |
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| Publication Number | Publication Date |
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| JPH1112006A JPH1112006A (en) | 1999-01-19 |
| JP3549707B2 true JP3549707B2 (en) | 2004-08-04 |
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| JP4509339B2 (en) * | 2000-09-18 | 2010-07-21 | 電気化学工業株式会社 | Cement admixture and cement composition |
| JP4567211B2 (en) * | 2001-01-29 | 2010-10-20 | 電気化学工業株式会社 | Expandable material and cement composition |
| JP4937465B2 (en) * | 2001-05-31 | 2012-05-23 | 電気化学工業株式会社 | Cement admixture and cement composition |
| JP4559090B2 (en) * | 2004-01-28 | 2010-10-06 | 太平洋マテリアル株式会社 | Expandable admixture and method for producing the same |
| JP5052778B2 (en) * | 2005-11-10 | 2012-10-17 | 電気化学工業株式会社 | Expandable material, cement composition, and cement concrete using the same |
| JP4853619B2 (en) * | 2005-11-29 | 2012-01-11 | 太平洋マテリアル株式会社 | Expandable admixture for resin finish floor and its use |
| JP4679534B2 (en) * | 2007-02-16 | 2011-04-27 | 電気化学工業株式会社 | Expandable material, cement composition, and cement concrete using the same |
| JP4809278B2 (en) * | 2007-03-27 | 2011-11-09 | 電気化学工業株式会社 | Intumescent material, cement composition, and hardened cement body using the same |
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