JP4244264B2 - Cement admixture and cement composition - Google Patents
Cement admixture and cement composition Download PDFInfo
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- JP4244264B2 JP4244264B2 JP2000184055A JP2000184055A JP4244264B2 JP 4244264 B2 JP4244264 B2 JP 4244264B2 JP 2000184055 A JP2000184055 A JP 2000184055A JP 2000184055 A JP2000184055 A JP 2000184055A JP 4244264 B2 JP4244264 B2 JP 4244264B2
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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
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/008—Cement and like inorganic materials added as expanding or shrinkage compensating ingredients in mortar or concrete compositions, the expansion being the result of a recrystallisation
-
- 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
- C04B7/00—Hydraulic cements
- C04B7/02—Portland cement
- C04B7/04—Portland cement using raw materials containing gypsum, i.e. processes of the Mueller-Kuehne type
-
- 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
- C04B7/00—Hydraulic cements
- C04B7/36—Manufacture of hydraulic cements in general
-
- 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
- C04B2111/34—Non-shrinking or non-cracking materials
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、主に、土木・建築分野において使用されるセメント混和材及びセメント組成物に関する。
【０００２】
【従来の技術】
セメント・コンクリートのひび割れ低減や曲げ耐力の向上は、コンクリート構造物の信頼性、耐久性、美観等の観点から重要であり、これらを改善する効果のあるセメント混和材である膨張材の更なる技術の進展が望まれている。従来より、セメント・コンクリートに膨張性を与えるセメント混和材としては、例えば、遊離石灰−カルシウムシリケート−無水セッコウ系膨張材（特公昭56-23936号公報）や、遊離石灰−カルシウムシリケート−間隙質−無水セッコウ系膨張材（特公昭53-31170号公報）等があった。しかしながら、これらの膨張材は今日求められる要求性能を必ずしも満足するものではなかった。即ち、近年では、コンクリートの高性能化を目的として、高流動コンクリートや高強度コンクリートの開発が盛んに行われているが、これらのコンクリートにおいては膨張材の効果が十分に発揮されないことが指摘されている。そのため、膨張材の混和率が小さくても大きな膨張性を付与できる膨張性能の優れた膨張材の開発が待たれているのが実状である。また、最近では、従来の仕様規定型の設計体系から、性能規定型の設計体系への移行が検討されており、これまでやや軽視されていた耐久性についても明確な性能規定が定められ、ひび割れの耐久性に対する影響の定量化がなされるものと考えられる。この場合、ひび割れ低減に効果のある膨張材を広範に利用するためには、使用量を少なくして、経済的負担を小さくすることが不可欠である。
【０００３】
【発明が解決しようとする課題】
しかしながら、膨張材の遊離石灰含有量を高めることによって、膨張性能に優れる膨張材とすることも可能であるが、単に遊離石灰含有量を高めて膨張性能を向上した場合には、耐風化性が著しく低下し、貯蔵期間中に性能の低下を起こすので、品質の安定した膨張材とならないものであった。
そこで本発明者らは、課題を解決すべく種々の検討を重ねた結果、特定の組成を持つ遊離石灰−カルシウムアルミノフェライト−カルシウムシリケート−無水セッコウ系膨張材が膨張性能に優れ、且つ、耐風化性にも優れることを知見し、本発明を完成するに至った。
【０００４】
【課題を解決するための手段】
即ち、本発明は、ＣａＯ原料、Ａｌ2Ｏ3原料、Ｆｅ2Ｏ3原料、ＳｉＯ2原料及びＣａＳＯ4原料を熱処理して得られる物質であって、遊離石灰、カルシウムアルミノフェライト、カルシウムシリケート及び無水セッコウを含有してなり、全ＣａＯ量に対してＣａＳＯ4含有量が２０％を超えることを特徴とするセメント混和材であり、珪酸率が１．０未満であることを特徴とする該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る。
なお、本発明で使用する％、部は、質量単位を表す。
【０００５】
【発明の実施の形態】
以下、本発明を更に詳細に説明する。
【０００６】
本発明のセメント混和材は、ＣａＯ原料、Ａｌ2Ｏ3原料、Ｆｅ2Ｏ3原料、ＳｉＯ2原料及びＣａＳＯ4原料を熱処理して得られる物質であって、遊離石灰、カルシウムアルミノフェライト、カルシウムシリケート及び無水セッコウを含有してなるものであり、全ＣａＯ量に対してＣａＳＯ4含有量が２０％を超えることを特徴としている。全ＣａＯ量に対してＣａＳＯ4含有量が２０％以下では、優れた膨張性能が得られない場合や、風化が著しく工業的に有益でない。ここで全ＣａＯ量とは、化学分析により得られる化学組成のＣａＯの総量を意味するもので、ＣａＳＯ4含有量とは、化学組成から計算で算出した化合物組成の割合である。
【０００７】
本発明では、セメント混和材の珪酸率が１．０未満である組成のものが特に優れた膨張性能を示す。珪酸率が１．０以上では優れた膨張性能が得られない場合や、風化が著しく工業的に有益でない場合がある。本発明で言う珪酸率とは、ＳｉＯ2量、Ａｌ2Ｏ3量及びＦｅ2Ｏ3量より次式から算出される。
珪酸率＝ＳｉＯ2／（Ａｌ2Ｏ3＋Ｆｅ2Ｏ3）
珪酸率は０．３程度から０．７５程度の範囲が好ましく、０．５程度がより好ましい。珪酸率が０．３程度以下では焼成時に融液相が多く生成し、焼成が困難になる場合があり、０．７５程度を超えると耐風化性が低下する傾向がある。
【０００８】
本発明のセメント混和材中の化合物の組成割合については、特に限定されるものではないが、セメント混和材１００部中、遊離石灰は４０〜７０部が好ましく、４５〜６０部がより好ましい。また、カルシウムアルミノフェライトは５〜２０部が好ましく、１０〜１５部がより好ましい。カルシウムシリケートは５〜２０部が好ましく、１０〜１５部がより好ましい。更に、無水セッコウは１６〜３０部が好ましく、２０〜２５部がより好ましい。セメント混和材中の各化合物の組成割合が前記の範囲にないと、優れた膨張特性が得られない場合がある。
【０００９】
本発明の遊離石灰とは、通常、ｆ−ＣａＯと呼ばれているものである。
本発明のカルシウムアルミノフェライトとは、ＣａＯ−Ａｌ2Ｏ3−Ｆｅ2Ｏ3系化合物を総称するものであり、特に限定されるものではないが、一般的に、ＣａＯをＣ、Ａｌ2Ｏ3をＡ、Ｆｅ2Ｏ3をＦとすると、Ｃ4ＡＦ、Ｃ6Ａ2Ｆ及びＣ6ＡＦ2等の化合物がよく知られている。通常は、Ｃ4ＡＦとして存在していると考えて良い。本発明では、カルシウムアルミノフェライトを以下、Ｃ4ＡＦと略記する。 本発明のカルシウムシリケートとは、ＣａＯ−ＳｉＯ2系化合物を総称するものであり、特に限定されるものではないが、一般的に、ＣａＯをＣ、ＳｉＯ2をＳとすると、Ｃ3ＳやＣ2Ｓ等の化合物が知られている。
【００１０】
本発明のセメント混和材を製造する際、ＣａＯ原料、Ａｌ2Ｏ3原料、Ｆｅ2Ｏ3原料、ＳｉＯ2原料及びＣａＳＯ4原料を熱処理して、遊離石灰、Ｃ4ＡＦ、カルシウムシリケート及び無水セッコウからなる物質を合成して製造することが必要である。遊離石灰、Ｃ4ＡＦ、カルシウムシリケート及び無水セッコウを別々に合成し、混合してセメント混和材を製造したのでは本発明の効果は得られない。即ち、ＣａＯ原料、Ａｌ2Ｏ3原料及びＦｅ2Ｏ3原料を熱処理して、遊離石灰とＣ4ＡＦからなる物質を合成し、これにカルシウムシリケートと無水セッコウを混合して製造した場合や、ＣａＯ原料、Ａｌ2Ｏ3原料、Ｆｅ2Ｏ3原料及びＳｉＯ2原料を熱処理して、遊離石灰、Ｃ4ＡＦ及びカルシウムシリケートからなる物質を合成して、これに無水セッコウを混合して製造した場合には本発明の効果は得られない。
【００１１】
ＣａＯ原料、Ａｌ2Ｏ3原料、Ｆｅ2Ｏ3原料、ＳｉＯ2原料及びＣａＳＯ4原料を熱処理して、遊離石灰、Ｃ4ＡＦ、カルシウムシリケート及び無水セッコウからなるセメント混和材を製造したかどうかは、例えば、粉砕物中の１００μｍ以上の粗粒子を顕微鏡観察（SEM-EDS）等で組成分析を行い、遊離石灰、Ｃ4ＡＦ、カルシウムシリケート及び無水セッコウが混在していることを確認することによって判別できる。
【００１２】
原料の熱処理方法は、特に限定されるものではないが、電気炉やキルンを使用して行い、その際の熱処理温度は、１２００〜１６００℃の範囲が好ましく、１２５０〜１５００℃の範囲がより好ましい。１２００℃未満では、得られたセメント混和材の膨張性能が十分でなく、１６００℃を超えると無水セッコウが分解する場合がある。
【００１３】
ＣａＯ原料としては、石灰石や消石灰等が挙げられ、Ａｌ2Ｏ3原料としてはボーキサイトやアルミ残灰等が挙げられ、Ｆｅ2Ｏ3原料としては銅カラミや市販の酸化鉄が挙げられ、ＳｉＯ2原料としては粘土質やケイ石等が挙げられ、更にＣａＳＯ4原料としては、二水セッコウ、半水セッコウ及び無水セッコウ等が挙げられる。これら原料中には不純物が存在する。その具体例としては、ＭｇＯ、ＴｉＯ2、Ｐ2Ｏ5、Ｎａ2Ｏ、Ｋ2Ｏ等が挙げられ、本発明の目的を実質的に阻害しない範囲では特に問題とはならない。
【００１４】
本発明のセメント混和材の粒度は、特に限定されるものではないが、通常、ブレーン比表面積で１５００〜９０００ｃｍ2／ｇが好ましく、２５００〜４０００ｃｍ2／ｇがより好ましい。セメント混和材の粒度が１５００ｃｍ2／ｇ未満では、長期耐久性が悪くなる場合があり、９０００ｃｍ2／ｇを超えると充分な膨張性能が得られない場合がある。
【００１５】
本発明のセメント混和材の使用量は、特に限定されるものではないが、通常、セメントとセメント混和材の合計からなるセメント組成物１００部中、３〜１２部が好ましく、５〜９部がより好ましい。３部未満では、充分な膨張性能が得られない場合があり、１２部を超えて使用すると過膨張となりクラックを生じる場合がある。
【００１６】
本発明のセメントとしては、普通、早強、超早強、低熱及び中庸熱等各種ポルトランドセメントと、これらセメントに、高炉スラグ、フライアッシュ及びシリカを混合した各種混合セメント、並びに石灰石粉末等を混合したフィラーセメント等がある。
【００１７】
本発明のセメント混和材及びセメント組成物に砂、砂利等の骨材の他、減水剤、高性能減水剤、ＡＥ減水剤、高性能ＡＥ減水剤、流動化剤、消泡剤、増粘剤、防錆剤、防凍剤、収縮低減剤、高分子エマルジョン及び凝結調整剤、並びにセメント急硬材、ベントナイト等の粘土鉱物及びハイドロタルサイト等のアニオン交換体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使用することが可能である。
【００１８】
本発明では、各材料の混合方法は、特に限定されるものではなく、それぞれの材料を施工時に混合しても良いし、予めその一部、或いは全部を混合しておいても差し支えない。混合装置としては、既存の如何なる装置も使用可能であり、例えば、傾胴ミキサ、オムニミキサ、ヘンシェルミキサ、Ｖ型ミキサ及びナウタミキサ等が挙げられる。
【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、Ａｌ2Ｏ3原料、Ｆｅ2Ｏ3原料、ＳｉＯ2原料及びＣａＳＯ4原料を配合し、混合粉砕した後、１３５０℃で熱処理して表１に示すような組成の物質を合成し、ボールミルを用いて、ブレーン比表面積３５００±３００ｃｍ2／ｇに粉砕してセメント混和材を調製した。セメント混和材を粉末Ｘ線回折法（以下、XRD）で同定し、構成化合物を調べた。セメント混和材の化合物組成は化学組成とXRDの同定結果を基に計算により算出した。化学組成はJIS R 5202に準じて求めた。セメント混和材の風化抵抗性を促進風化試験によって評価した。セメントと、セメント混和材からなるセメント組成物１００部に対して、セメント混和材を７部使用し、水／セメント組成物比＝５０％、セメント組成物／砂比＝１／３のモルタルを調製し、長さ変化率の測定を行った。結果を表１に併記する。
【００２１】
＜使用材料＞
ＣａＯ原料：試薬１級炭酸カルシウム
Ａｌ2Ｏ3原料：試薬１級酸化アルミニウム
Ｆｅ2Ｏ3原料：試薬１級酸化第二鉄
ＳｉＯ2原料：試薬１級二酸化ケイ素
ＣａＳＯ4原料：試薬１級二水セッコウ
セメント：市販普通ポルトランドセメント
砂：JIS標準砂（ISO679準拠）
市販膨張材：カルシウムサルホアルミネート系
【００２２】
＜測定方法＞
長さ変化率：JIS A 6202に準じて測定。材齢7日の長さ変化率を表示。
促進風化試験：セメント混和材３ｇをスチロール瓶に入れ、２０℃・相対湿度７０％の環境試験室内で暴露放置し、材齢３日後に回収して１０００℃で３０分間強熱した際の減量を測定して評価した。
【００２３】
【表１】
表１より、本発明のセメント混和材を使用したモルタルは、長さ変化率が大きく膨張性能に優れ、且つ、強熱減量が小さく耐風化性に優れていることが判る。
【００２５】
実施例２
表２に示すようにセメント混和材中の遊離石灰含有量を５０部、珪酸率を０．４９とし、無水セッコウ含有量を変えたこと以外は、実施例１と同様に行った。結果を表２に併記する。
【００２６】
【表２】
表２より、本発明の全ＣａＯ量に対してＣａＳＯ4含有量が２０％を超えるセメント混和材を使用したモルタルは、長さ変化率が大きく膨張性能に優れ、且つ、強熱減量が小さく耐風化性に優れていることが判る。
【００２８】
実施例３
表３に示すようにセメント混和材中の遊離石灰含有量を５０部、無水セッコウ含有量を２５部とし、Ｃ4ＡＦとＣ3Ｓの含有量を変えたこと以外は、実施例１と同様に行った。結果を表３に併記する。
【００２９】
【表３】
表３より、本発明のセメント混和材の珪酸率が１．０未満のモルタルは、特に長さ変化率が大きく膨張性能に優れ、且つ、強熱減量が小さく耐風化性に優れていることが判る。
【００３１】
実施例４
実験No.1-8のセメント混和材を使用し、セメント組成物１００部に対するセメント混和材の使用量を表４に示すように変えたこと以外は、実施例１と同様に行った。結果を表４に併記する。
【００３２】
【表４】
表４より、本発明のセメント混和材の使用量が増加するにつれ長さ変化率が増加することが判る。
【００３４】
【発明の効果】
本発明に依れば、従来のものと比べ、膨張性能及び耐風化性に優れるセメント混和材及びセメント組成物が得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a cement admixture and a cement composition used in the field of civil engineering and construction.
[0002]
[Prior art]
Reduction of cracks in cement and concrete and improvement of bending strength are important from the viewpoint of reliability, durability, aesthetics, etc. of concrete structures, and further technology for expansion materials that are cement admixtures that have the effect of improving these. The progress is desired. Conventionally, as cement admixtures that impart expansibility to cement and concrete, for example, free lime-calcium silicate-anhydrous gypsum-based expansive material (Japanese Patent Publication No. 56-23936), free lime-calcium silicate-porosity- There was an anhydrous gypsum-based expansion material (Japanese Patent Publication No. 53-31170). However, these expansion materials do not always satisfy the required performance required today. That is, in recent years, development of high-fluidity concrete and high-strength concrete has been actively conducted for the purpose of improving the performance of concrete, but it has been pointed out that the effect of the expandable material is not sufficiently exhibited in these concretes. ing. Therefore, it is the actual situation that the development of an expansion material having excellent expansion performance capable of imparting a large expansion property even if the mixing ratio of the expansion material is small is awaited. Recently, the transition from the conventional specification-based design system to the performance-based design system has been studied, and a clear performance specification has been established for durability that has been neglected until now, and cracking has occurred. It is thought that the effect on the durability of the material will be quantified. In this case, in order to make extensive use of the expansion material that is effective in reducing cracks, it is essential to reduce the amount of use and reduce the economic burden.
[0003]
[Problems to be solved by the invention]
However, by increasing the free lime content of the expansion material, it is also possible to make an expansion material with excellent expansion performance, but when the expansion performance is improved simply by increasing the free lime content, the weathering resistance is Since it deteriorated remarkably and caused a decrease in performance during the storage period, it could not be an expanded material with a stable quality.
Therefore, as a result of various investigations to solve the problem, the present inventors have found that a free lime-calcium aluminoferrite-calcium silicate-anhydrous gypsum-based expansion material having a specific composition has excellent expansion performance and is resistant to wind. As a result, the present invention has been completed.
[0004]
[Means for Solving the Problems]
That is, the present invention is a substance obtained by heat treatment of CaO raw material, Al 2 O 3 raw material, Fe 2 O 3 raw material, SiO 2 raw material and CaSO 4 raw material, and includes free lime, calcium aluminoferrite, calcium silicate and anhydrous A cement admixture comprising gypsum, characterized in that the CaSO 4 content exceeds 20% with respect to the total CaO content, wherein the silicic acid ratio is less than 1.0. A cement composition comprising cement and the cement admixture.
In addition,% and part used by this invention represent a mass unit.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0006]
The cement admixture of the present invention is a substance obtained by heat-treating a CaO raw material, an Al 2 O 3 raw material, an Fe 2 O 3 raw material, an SiO 2 raw material and a CaSO 4 raw material, and is free lime, calcium aluminoferrite, calcium silicate And anhydrous gypsum, and the CaSO 4 content exceeds 20% with respect to the total CaO content. When the content of CaSO 4 is 20% or less with respect to the total amount of CaO, excellent expansion performance cannot be obtained or weathering is remarkably not industrially useful. Here, the total CaO amount means the total amount of CaO having a chemical composition obtained by chemical analysis, and the CaSO 4 content is a ratio of the compound composition calculated by calculation from the chemical composition.
[0007]
In the present invention, a composition having a cement admixture with a silicic acid ratio of less than 1.0 exhibits particularly excellent expansion performance. When the silicic acid ratio is 1.0 or more, excellent expansion performance may not be obtained, or weathering may be remarkably not industrially useful. The silicic acid ratio referred to in the present invention is calculated from the following equation from the amount of SiO 2, the amount of Al 2 O 3 and the amount of Fe 2 O 3 .
Silicic acid ratio = SiO 2 / (Al 2 O 3 + Fe 2 O 3 )
The silicic acid ratio is preferably in the range of about 0.3 to about 0.75, more preferably about 0.5. When the silicic acid ratio is about 0.3 or less, a large amount of melt phase is generated during firing, and firing may become difficult. When it exceeds about 0.75, weathering resistance tends to decrease.
[0008]
Although it does not specifically limit about the composition ratio of the compound in the cement admixture of this invention, 40-70 parts are preferable in 100 parts of cement admixtures, and 45-60 parts are more preferable. The calcium aluminoferrite is preferably 5 to 20 parts, more preferably 10 to 15 parts. The calcium silicate is preferably 5 to 20 parts, more preferably 10 to 15 parts. Furthermore, 16-30 parts is preferable and, as for anhydrous gypsum, 20-25 parts is more preferable. If the composition ratio of each compound in the cement admixture is not within the above range, excellent expansion characteristics may not be obtained.
[0009]
The free lime of the present invention is usually called f-CaO.
The calcium aluminoferrite of the present invention is a generic term for CaO—Al 2 O 3 —Fe 2 O 3 compounds and is not particularly limited, but in general, CaO is C, Al 2 O 3. When A is Fe and Fe 2 O 3 is F, compounds such as C 4 AF, C 6 A 2 F and C 6 AF 2 are well known. Normally, it can be considered that it exists as C 4 AF. In the present invention, calcium aluminoferrite is hereinafter abbreviated as C 4 AF. The calcium silicate of the present invention is a generic name for CaO—SiO 2 compounds and is not particularly limited. Generally, when CaO is C and SiO 2 is S, C 3 S or C compounds such as 2 S are known.
[0010]
When producing the cement admixture of the present invention, heat treatment is carried out on the CaO raw material, Al 2 O 3 raw material, Fe 2 O 3 raw material, SiO 2 raw material and CaSO 4 raw material to produce free lime, C 4 AF, calcium silicate and anhydrous gypsum. It is necessary to synthesize and produce a material consisting of The effect of the present invention cannot be obtained if free lime, C 4 AF, calcium silicate and anhydrous gypsum are synthesized separately and mixed to produce a cement admixture. That is, when a CaO raw material, an Al 2 O 3 raw material and an Fe 2 O 3 raw material are heat-treated to synthesize a substance composed of free lime and C 4 AF, and mixed with calcium silicate and anhydrous gypsum, A CaO raw material, an Al 2 O 3 raw material, an Fe 2 O 3 raw material, and an SiO 2 raw material were heat-treated to synthesize a substance composed of free lime, C 4 AF, and calcium silicate, and mixed with anhydrous gypsum. In this case, the effect of the present invention cannot be obtained.
[0011]
Whether or not a cement admixture made of free lime, C 4 AF, calcium silicate and anhydrous gypsum was manufactured by heat-treating CaO raw material, Al 2 O 3 raw material, Fe 2 O 3 raw material, SiO 2 raw material and CaSO 4 raw material For example, by analyzing the composition of coarse particles of 100 μm or more in the pulverized product by microscopic observation (SEM-EDS), etc., and confirming that free lime, C 4 AF, calcium silicate and anhydrous gypsum are mixed Can be determined.
[0012]
The heat treatment method of the raw material is not particularly limited, but is performed using an electric furnace or kiln, and the heat treatment temperature at that time is preferably in the range of 1200 to 1600 ° C, more preferably in the range of 1250 to 1500 ° C. . If it is less than 1200 degreeC, the expansion performance of the obtained cement admixture is not enough, and when it exceeds 1600 degreeC, anhydrous gypsum may decompose | disassemble.
[0013]
The CaO raw material include limestone or slaked lime, etc., as the Al 2 O 3 raw material include bauxite, aluminum residual ash, etc., as the Fe 2 O 3 raw material include copper Karami and commercial iron oxide, SiO 2 Examples of the raw material include clay and quartzite, and examples of the CaSO 4 raw material include dihydrate gypsum, half water gypsum and anhydrous gypsum. Impurities are present in these raw materials. Specific examples thereof include MgO, TiO 2 , P 2 O 5 , Na 2 O, K 2 O and the like, and there is no particular problem as long as the object of the present invention is not substantially inhibited.
[0014]
Although the particle size of the cement admixture of the present invention is not particularly limited, it is usually preferably 1500 to 9000 cm 2 / g, more preferably 2500 to 4000 cm 2 / g in terms of specific surface area of branes. If the particle size of the cement admixture is less than 1500 cm 2 / g, the long-term durability may deteriorate, and if it exceeds 9000 cm 2 / g, sufficient expansion performance may not be obtained.
[0015]
The amount of the cement admixture of the present invention is not particularly limited, but usually 3 to 12 parts are preferable and 5 to 9 parts are preferable in 100 parts of a cement composition consisting of the sum of cement and cement admixture. More preferred. If it is less than 3 parts, sufficient expansion performance may not be obtained, and if it exceeds 12 parts, it may overexpand and cracks may occur.
[0016]
As the cement of the present invention, various portland cements such as normal, early strength, ultra-early strength, low heat and moderate heat, mixed blast furnace slag, fly ash and silica mixed with these cements, limestone powder, etc. are mixed. Filler cement.
[0017]
In addition to aggregates such as sand and gravel, the cement admixture and cement composition of the present invention, water reducing agent, high performance water reducing agent, AE water reducing agent, high performance AE water reducing agent, fluidizing agent, antifoaming agent, thickening agent 1 type or 2 types or more of rust preventives, antifreeze agents, shrinkage reducing agents, polymer emulsions and setting modifiers, cement hardeners, clay minerals such as bentonite and anion exchangers such as hydrotalcite The present invention can be used within a range that does not substantially impair the object of the present invention.
[0018]
In the present invention, the mixing method of each material is not particularly limited, and the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance. Any existing apparatus can be used as the mixing apparatus, and examples thereof include a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer.
[0019]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
[0020]
Example 1
A CaO raw material, an Al 2 O 3 raw material, an Fe 2 O 3 raw material, an SiO 2 raw material and a CaSO 4 raw material were blended, mixed and pulverized, and then heat treated at 1350 ° C. to synthesize a material having the composition shown in Table 1, A cement admixture was prepared by pulverizing to a Blaine specific surface area of 3500 ± 300 cm 2 / g using a ball mill. The cement admixture was identified by powder X-ray diffraction (hereinafter referred to as XRD), and the constituent compounds were examined. The compound composition of cement admixture was calculated by calculation based on the chemical composition and XRD identification results. The chemical composition was determined according to JIS R 5202. The weathering resistance of cement admixture was evaluated by accelerated weathering test. 7 parts of cement admixture is used for 100 parts of cement composition consisting of cement and cement admixture to prepare a mortar with a water / cement composition ratio = 50% and a cement composition / sand ratio = 1/3. The length change rate was measured. The results are also shown in Table 1.
[0021]
<Materials used>
CaO raw material: Reagent primary calcium carbonate Al 2 O 3 raw material: Reagent primary aluminum oxide Fe 2 O 3 raw material: Reagent primary ferric oxide SiO 2 raw material: Reagent primary silicon dioxide CaSO 4 raw material: Reagent primary secondary water Gypsum cement: Commercially available Portland cement sand: JIS standard sand (ISO679 compliant)
Commercial expansion material: Calcium sulfoaluminate series
<Measurement method>
Length change rate: Measured according to JIS A 6202. Displays the rate of change in length of 7 days.
Accelerated weathering test: 3 g of cement admixture was placed in a styrene bottle, left exposed in an environmental test chamber at 20 ° C and 70% relative humidity, recovered after 3 days of age, and reduced in weight when ignited at 1000 ° C for 30 minutes. Measured and evaluated.
[0023]
[Table 1]
From Table 1, it can be seen that the mortar using the cement admixture of the present invention has a large rate of change in length and excellent expansion performance, and has a small ignition loss and excellent weathering resistance.
[0025]
Example 2
As shown in Table 2, the same procedure as in Example 1 was carried out except that the free lime content in the cement admixture was 50 parts, the silicic acid ratio was 0.49, and the anhydrous gypsum content was changed. The results are also shown in Table 2.
[0026]
[Table 2]
From Table 2, the mortar using the cement admixture having a CaSO 4 content exceeding 20% with respect to the total CaO amount of the present invention has a large rate of change in length, excellent expansion performance, small ignition loss, and wind resistance. It turns out that it is excellent in chemical conversion.
[0028]
Example 3
As shown in Table 3, the content of free lime in the cement admixture was 50 parts, the content of anhydrous gypsum was 25 parts, and the contents of C 4 AF and C 3 S were changed. Went to. The results are also shown in Table 3.
[0029]
[Table 3]
From Table 3, the mortar having a silicic acid ratio of less than 1.0 in the cement admixture of the present invention has a particularly high rate of change in length and excellent expansion performance, and has a small ignition loss and excellent weathering resistance. I understand.
[0031]
Example 4
The same procedure as in Example 1 was performed except that the cement admixture of Experiment No. 1-8 was used and the amount of the cement admixture used for 100 parts of the cement composition was changed as shown in Table 4. The results are also shown in Table 4.
[0032]
[Table 4]
From Table 4, it can be seen that the rate of change in length increases as the amount of the cement admixture of the present invention increases.
[0034]
【The invention's effect】
According to the present invention, it is possible to obtain a cement admixture and a cement composition which are superior in expansion performance and weathering resistance as compared with conventional ones.
Claims (3)
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| JP2000184055A JP4244264B2 (en) | 2000-06-20 | 2000-06-20 | Cement admixture and cement composition |
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| JP2000184055A JP4244264B2 (en) | 2000-06-20 | 2000-06-20 | Cement admixture and cement composition |
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