JP3920507B2

JP3920507B2 - Water-absorbing cement molding hardened body

Info

Publication number: JP3920507B2
Application number: JP23597299A
Authority: JP
Inventors: 芳春渡邉; 哲也安藤; 邦雄進藤; 隆二伊藤
Original assignee: Denki Kagaku Kogyo KK
Current assignee: Denka Co Ltd
Priority date: 1999-08-23
Filing date: 1999-08-23
Publication date: 2007-05-30
Anticipated expiration: 2019-08-23
Also published as: JP2001058864A

Description

【０００１】
【発明が属する技術分野】
本発明は、表面に藻や苔が自然育成し易く、人に優しい触感を与える吸水性セメント硬化体及びその製法に関する。
【０００２】
【従来の技術】
従来、圧縮強度が１０〜６０Ｎ／ｍｍ²のモルタルやコンクリート等のセメント硬化体の吸水率は多くても４〜６％であり、その吸水速度も遅く、基本的には不透水性の密実な硬化体である。したがって、環境面からコンクリートの美観対策を施す場合は植生ブロック等に見られるように、植物が根を張れるような連続した空間を有するコンクリートを作製しその空間内に土を入れ、植物やその種を人工的に植える等の対策が行われていた。
一方、建設発生土は最終処分場で埋め立てるに際し好ましい素材であるが、最終処分場には地下水を汚染するような他の廃棄物が共に廃棄されるため、嫌われる傾向にあった。そのため最終処分場の建設もままならず、大量に発生する建設発生土の処分が困難になっているという問題がある。
【０００３】
特願平１０−１３５１０６号には、セメントと石こうとシリカフューム等を配合した固化材及びこれを用いた粒子径が４４μｍ以下の汚泥固化方法を提案した。この提案は基本的には汚泥中の水分を利用して固化材と汚泥と細骨材と粗骨材を練混ぜるもので、４４μｍ以下の汚泥のみの固化方法を対象とし、路盤材等への利用を目的としたものであり、吸水率の向上や藻や苔の育成及び植生効果については全く考慮されていない。
また、特開平９−１４２８９８号及び特開平９−１３２４４０号公報には、土の風合いを持ち、強度も吸水率も大きい不焼成硬化体も提案されているが、この提案は粘土と消石灰及び／又は生石灰を配合してオートクレーブ養生するものであり、オートクレーブ養生は凍結融解耐久性が劣るという問題を有する。
【０００４】
【発明が解決しようとする課題】
そこで、オートクレーブ養生ではなく通常の常温又は蒸気養生を用いて凍結融解耐久性を向上させ、且つ、セメント硬化体表面には藻や苔を自然育成させる環境を整えることができるセメント硬化体を、処理に窮していた建設発生土を有効利用して製造することができる技術が求められていた。
【０００５】
【課題を解決するための手段】
本発明は上記課題を解決することを目的とし、その構成は、セメント、土及び水を練混ぜて振動成形、加圧成形又は振動加圧成形によって得られた吸水率が１０〜３０％の成形硬化体であって、土として、絶乾状態で４４μｍ以下の微粒分含有率が５〜３０重量％である、一般常識上の土を使用し、セメント或いはセメントに混和材を添加した総量：土の重量配合比率が１：１〜１：４であると共に、水／セメント重量比或いは水／（セメントに混和材を配合した総量）の重量比率が１．２以下であり、混和材が、粘土鉱物の焼成粉末、石こう、活性シリカの少なくとも１種であることを特徴とする。
【０００６】
本発明の吸水性セメント硬化体は、水をかけると数秒〜数分の速さで吸水して水分をそのまま保持する。したがって、従来のコンクリートに代えて使用すると藻や苔が自然に育成し、植生効果も発揮して環境を改善する。また、本発明の吸水性セメント硬化体の表面に触れた場合は人肌にしっとりとした優しい感触を与える。更に、従来のコンクリート構造物は太陽熱等で熱せられて一度上昇した温度は冷めにくいが、本発明の吸水性セメント硬化体は温度が上がり難いので建築物への使用箇所によっては調温・調湿効果を発揮し、優れた環境を保持することができる。更に、本発明の吸水性セメント硬化体は通常の土、建設発生土を大量にセメントに混合して得られるため、建設発生土の有効利用にもなる。
【０００７】
【発明の実施の形態】
本発明に用いるセメントとは普通、早強、超早強、白色、中庸熱、低発熱及び耐硫酸塩セメント等の各種ポルトランドセメント；シリカ粉末、フライアッシュ、高炉スラグ等を混合した各種混合セメント；エトリンガイトの生成により急硬する急硬性セメントであり、アルミナセメントは好ましくない。
【０００８】
本発明に使用する土は、一般常識上の土であり、赤土、黄土、黒土、白土等が使用できる。建設発生土が基本的に望ましいが天然産出土であっても使用可能である。建設発生土とはビル等の建造物の建設、トンネル工事、河川や海岸の護岸、道路建設、修復等種々の工事により掘り起こされた土を包含する。
４４μｍ以下の微粒分含有量が５〜３０重量％の土が好ましい。４４μｍ以下の微粒分とは、土を１１０℃で２４時間乾燥した絶乾状態で測定し、ＪＩＳ標準試験篩の３５０メッシュ、呼び寸法４４μｍを通過する粒子である。得られた土がこの範囲を外れた場合には微粒分の多い土と微粒分の少ない土を混合して調節し、使用することができる。
微粒分が５重量％未満では土の配合率が大きくても、吸水率１０％以上のセメント硬化体が得られ難く、微粒分が３０重量％を越えると土の配合比率を小さくしても実用的な強度が得られないか、或いは吸水率が３０重量％を越え、適量の空気が連行されていても耐凍害性が低下するので好ましくない。
【０００９】
なお、本発明のセメント硬化体は基本的にはモルタル硬化体であるが、絶乾状態で、土に径５ｍｍを越える礫（粗骨材）が混入していても最大２０重量％までなら問題ないが、それを越える量の場合は吸水率が低下して好ましくない。なお、使用できる粗骨材の最大径は２５ｍｍである。
【００１０】
本発明においては硬化体の吸水率は１０〜３０％、好ましくは１５〜２５％である。ここで、吸水率とは、径５ｃｍ、長さ１０ｃｍの円柱状硬化体を２０℃の水中に２４時間浸漬して飽水状態としたときの重量（Ａ）を測定し、１０５℃で２４時間乾燥したときの重量（Ｂ）を測定し、１００（Ａ−Ｂ）／Ｂ（％）で表す。
吸水率が１０％未満では藻や苔などが育成し難く、３０％を越えると実用的な１０Ｎ／ｍｍ²以上の強度が得られ難く、凍結融解耐久性も低下するので好ましくない。
【００１１】
本発明においては結合材としてセメントを用いるが、セメントの強度を高めるために後述するセメント以外の成分を配合し、この成分を混和材としてセメントと区別する。したがって、結合材とはセメント単独又はセメントと混和材の配合物を指称する。そして結合材：土の重量比率は１：１〜１：４である。なお、土は絶乾状態として計算する。結合材と土との配合比率が１：１未満では、呼び径４４μｍの篩を通過する微粒分が５重量％以上でも、吸水率が１０重量％以上のセメント硬化体が得られ難い。また１：４を越えると実用的な１０Ｎ／ｍｍ²以上の強度が得られないか、或いは実用的な強度と適正な吸水率が得られても凍結融解耐久性が低下するので好ましくない。
【００１２】
本発明においては水／結合材比を１．２以下、好ましくは１．０〜０．４５とする。１．２を越えると微粒分が多い場合に実用的な１０Ｎ／ｍｍ²以上の強度が得られない。０．４５未満では強度が大きくなり過ぎて吸水率が１０重量％以上にならず、藻や苔などの自然育成効果が得られない。
なお、本発明の水／結合材比は土を絶乾状態、或いは絶乾状態に換算したときの値であり、土が吸水する水量も含むものである。
【００１３】
また、柔らかさはＪＩＳＲ５２０１によるモルタルフロー値で３００ｍｍ以下が好ましい。３００ｍｍを越えるフロー値では凝結遅延が大きくなり、蒸気養生で製造する場合は熱膨張によるヒビ割れが生じ易い。また、本発明の混練物は粘着性が強くなるので成形方法により好ましいフロー値があり、振動成形で成形する場合のより好ましいフロー値は１２０〜２５０ｍｍである。１２０ｍｍ未満の場合は押出し成形や加圧成形を行うのが好ましい。
【００１４】
本発明において、吸水率をそれほど変化させずに強度を高める混和材成分として、粘土鉱物の焼成粉末、石こう、活性シリカの１種又は２種以上を使用する。これらは単独で使用しても強度を増大させる効果を有するが、併用すると更に高い強度が得られる。
【００１５】
粘土鉱物の焼成粉末とは、アルミナケイ酸塩を主成分とする粘土を６００〜１０００℃で焼成したものでメタカオリンで代表される。単独で使用する場合も他の混和材と併用する場合も、セメント１００重量部に対し２０重量部以下であり、好ましくは５〜１５重量部である。５重量部未満では強度増進効果が小さく、２０重量部を越えて使用しても強度増進効果は停滞する。
【００１６】
石こうは単独で使用する場合も他の混和材と併用する場合も、無水物換算でセメント１００重量部に対し１５重量部以下、好ましくは２〜１０重量部である。２重量部未満では強度増進効果は小さく、１５重量部を越えて使用しても強度増進効果は停滞するので好ましくない。石こうの種類は特に限定しないが、好ましくは不溶性又は難溶性無水石こうと呼称されるII型無水石こうであり、粉末度は３０００ｃｍ²／ｇ以上であればよい。
【００１７】
活性シリカとはシリカフューム、ケイ化木や籾の焼却灰、アエロジル等の非晶質のＳｉＯ₂を主成分とするものである。活性シリカは単独で使用する場合も他の混和材と併用する場合も、セメント１００重量部に対し３０重量部以下であり、好ましくは３〜２５重量部である。３重量部未満では強度増進効果が小さく、３０重量部を越えて使用しても強度増進効果は停滞する。
【００１８】
本発明においては減水剤を使用することが好ましい。減水剤の種類としては、通常のコンクリートでは単位水量の１０％程度まで低減するリグニンスルホン酸塩系、カルボン酸塩系、ポリオール系等の減水率の低い一般的な減水剤；これらにＡＥ剤を配合したＡＥ減水剤；通常のコンクリートでは単位量の２０〜３０％低減する高性能減水剤、高性能ＡＥ減水剤があり、中でも高性能減水剤、高性能ＡＥ減水剤が好ましい。一般的な減水剤やＡＥ減水剤は、メーカー指定量の２倍程度まで添加される。
高性能減水剤としてはポリアルキルアリルスルホン酸塩系とメラミン樹脂スルホン酸塩系があり、これらは比較的多く添加しても遅延性や空気連行性がなく添加量に応じて減水率が向上するという特性を有する。代表的な市販品の商標名としては、花王社製の「マイティ１５０」、グレースケミカルズ社製の「ＦＴ−５００」、日本製紙社製の「サンフローＰＳ」等がある。これらはセメント１００重量部に対し、固形分換算で多くても３．０重量部添加される。３．０重量部を越えて添加しても減水率の伸びは少ない。
【００１９】
高性能減水剤は空気連行性はないが、ＡＥ剤を併用して空気連行性を付与し、耐凍害性を改善する。
高性能ＡＥ減水剤はいわゆるポリカルボン酸塩系の減水剤であり、空気連行性を有するので耐凍害性を改善し、添加量に応じて減水率が向上するという特性を有するが、遅延性も大きくなる。したがって、高性能ＡＥ減水剤の場合は、結合材１００重量部に対して多くてもメーカー指定量の２倍量程度である。２倍を越える量の添加は遅延性が大きくなり過ぎて蒸気養生等を行う場合には熱膨張によるヒビ割れが生じ易い。高性能ＡＥ減水剤の市販品の商標名としては、ＭＭＢ社製の「レオビルドＰＳ８シリーズ」、藤沢薬品工業社製の「パリックシリーズ」、グレースケミカルズ社製の「ダーレックススーパーシリーズ」等が挙げられる。
【００２０】
本発明においては各種促進剤を適量使用すると、前養生時間や脱型強度を得るまでの時間を短縮できて好ましい。促進剤としては特に限定しないが、ギ酸、硝酸のカルシウム、マグネシウム、ナトリウム、カリウム塩、チオシアン酸のカルシウム、マグネシウム、ナトリウム、カリウム塩及び硫酸アルミニウム等が好ましい。
これらの促進剤は結合材（セメント＋混和材）に対して多くても２重量％、好ましくは０．２〜１．５％添加され、少ないと凝結促進効果が小さく、多過ぎると長期強度の伸びが抑制される。
【００２１】
吸水性セメント硬化体の製造に際しては、主成分を通常のモルタルミキサーやコンクリートミキサーを使用して混練することができる。より好ましくは、強制練りミキサーを用いてセメント、土、混和材及び他の添加剤に、全水量の７０〜８０％を一次水として添加して１〜３分間の一次練混ぜ後、残りの２０〜３０％を二次水として添加して数分間練混ぜる。成形方法は通常の外部又は内部振動機を用いた振動成形の他、前述のようにモルタルフロー値によっては、加圧成形、振動加圧成形によって行われる。
【００２２】
養生方法は特に限定がなく、常温でもよいが、プレキャスト製品として製造する場合は常圧蒸気養生が製造効率上好ましい。ただし、オートクレーブ養生は適量の空気を連行しても、冷却時に硬化体に微細なヒビ割れが入り、強度が高くても凍結融解耐久性が劣るので好ましくない。
常圧蒸気養生を行う場合は、練混ぜたものを型枠に流し込んだ後、前養生時間を経て４０〜１００℃の温度で養生する。
【００２３】
【実施例】
実施例１
下記７種類の土を集めた。
ａ地産発生土：４４μｍ以下の微粒分３重量％含む、灰黒土
ｂ地産発生土：４４μｍ以下の微粒分７重量％含む、黒土
ｃ地産発生土：４４μｍ以下の微粒分１３重量％含む、赤土
ｄ地産発生土：４４μｍ以下の微粒分１６重量％含む、黄土
ｅ地産発生土：４４μｍ以下の微粒分２４重量％含む、灰白色
ｆ地産発生土：４４μｍ以下の微粒分３２重量％含む、黄土
ｇ地産発生土：４４μｍ以下の微粒分３５重量％含む、灰白色
これらａ〜ｆの土を配合して４４μｍ以下の微粒分含有量が切りのよい数値になるように下記の７種類の試験土を調製した。
Ａ：ａ地産発生土（４４μｍ以下の微粒分３重量％、絶乾比重２.6１)
Ｂ：ｂ地産発生土とＡとの混合物（４４μｍ以下の微粒分５重量％、絶乾比重２.5８)
Ｃ：ｃ地産発生土とＢとの混合物（４４μｍ以下の微粒分１０重量％、絶乾比重２.4０)
Ｄ：ｄ地産発生土とＣとの混合物（４４μｍ以下の微粒分１５重量％絶乾比重２.3５)
Ｅ：ｅ地産発生土とＤとの混合物（４４μｍ以下の微粒分２０重量％、絶乾比重２.1３)
Ｆ：ｆ地産発生土とＥとの混合物（４４μｍ以下の微粒分３０重量％絶乾比重２.0１)
Ｇ：ｇ地産発生土（４４μｍ以下の微粒分３５重量％、絶乾比重２.0１）
【００２４】
表１及び表２に示す種類及び量の土（絶乾状態換算）を、表１及び表２に示す量のセメント及び水と遊星型の強制練りミキサーで練混ぜ、そのモルタルのフロー値をＪＩＳＲ５２０１により測定し表１及び表２に併記した。なお減水剤はリグニンスルホン酸系の一般のＡＥ減水剤をセメントに対し、固形分として０．２５％（メーカー指定量）添加した。練混ぜは普通ポルトランドセメントと土に全水量の８０％の水を加えて３分間一次練りを行い、次いで残りの２０％の水を添加して二次練りを３分間行った。得られたモルタルを用いて圧縮強度測定用として径１０ｃｍ、長さ２０ｃｍの供試体を３本、吸水率測定用として、径５ｃｍ、長さ１０ｃｍの供試体を３本、苔の育成状態測定用として１０×１０×４０ｃｍの供試体３本を振動台でそれぞれ形成し、５時間の前養生後、１５℃／時間の速度で２０℃の室温から８５℃まで上げて４時間保持し、翌日まで徐冷して脱型した。圧縮強度は２０℃、相対湿度８０％で、１４日間室内養生した後に測定した。苔の育成状態は林の中を流れる小川で行った。水が直接かからない川の縁に並べて６か月後の苔の発生と育成状態を観察した。苔の育成状態は次の基準で評価した。
×……全く発生なし
△……側面部に育成
○……側面部と木漏れ日の当たる表面部の一部にも育成
◎……全面に育成
これらの結果を表１及び表２に併記した。
【００２５】
【表１】

【表２】

【００２６】
表１及び表２より以下の事実が理解される。すなわち、土の中の微粒分が５重量％未満では、セメントに対する土の配合比率を１：４にしても吸水率は１０重量％未満であり苔の自然生育がない。微粒分５重量％では配合比率を１：１にし、水／セメント比を０．４５にすることにより吸水率１０％を越えることができる。同程度のフロー値を得るには、土の配合比率を大きくする程、微粒分の含有率を高くする程、水／セメント比は上昇し、圧縮強度も低下するが吸水率は増大する。本発明の範囲において、最も微粒分が多く、土の配合比率も高い実験Ｎo.１−２３では、実用的な強度、１０Ｎ／ｍｍ²以上にするための水／セメント比は１．２０であった。
【００２７】
微粒分が３０重量％を越えると、配合比率を１：１とし、水／セメント比を１以下にしても１０Ｎ／ｍｍ²以上の圧縮強度は得られず、圧縮強度は水／セメント比以外に微粒分の含有率にも大きく影響されることを示している。
苔の自然生育状態は、吸水率が１０％以上、１５％以上が好ましく、吸水率が大きくなるほど良く生育する。吸水率が３０％では、強度も１０Ｎ／ｍｍ²以上ぎりぎりであり、より好ましい吸水率の上限は強度のバランスも考慮すると２５％付近と考えられる。
【００２８】
実施例２
実施例１の実験Ｎo.１−０１〜１−０７及び１−２０〜１−２３について、実施例１と同様にして成形し、蒸気養生し、１４日間標準養生して１０×１０×４０ｃｍの供試体を得た。これを用いてＡＳＴＭＣ６６６（水中急速凍結、水中融解）に準じて凍結融解試験を行い、３００サイクル時の相対動弾性係数を測定し、その結果を表３に示した。
【００２９】
表３から明らかなように、セメントに対する土の比率が大きくなると動弾性係数も徐々に低下するが、セメント：土の配合比率が１：４を越えると急激に低下し６０％以下に達し、耐凍害性も悪化することが予測される。また、セメント：土の配合比率が同一でも微粒分が多い土では相対弾性係数が小さくなる傾向を示すが１：４までは６０％以上であり、差支えない。
【００３０】
【表３】

【００３１】
実施例３
実施例１の普通ポルトランドセメント１００重量部に対し、混和材として天然無水石こう（II型、粉末度４５００ｃｍ²／ｇ）、シリカフューム（粉末度２２ｍ²／ｇ）、メタカオリン（粉末度８５００ｃｍ²／ｇ）を表４及び表５に示す割合で配合し、結合材（セメント＋混和材）と土の配合比率を１：２．５とし、実施例１と同様にして練混ぜた後フロー値を測定した。実施例１と同様の供試体を作成し、同様の養生方法で養生し、圧縮強度と吸水率を表４及び表５に併記した。
なお、フロー値が１２０ｍｍ以上では振動台による振動成形とし、１２０ｍｍ未満では０．４Ｎ／ｍｍ²の圧力で加圧成形した。
【００３２】
実験Ｎo.３−１３は供試体の打込み面が熱膨張して数ｍｍ膨らみ、全体に微細なヒビ割れが入った。実験Ｎo.３−２３はヒビ割れ面は目視できないが打込み面がわずかに膨らんでいた。（表中☆印）
減水剤としては、下記のａ、ｂを固形分換算で表４及び表５に示す量添加した。
ａ……ナフタレンスルホン酸塩系の高性能減水剤と、セメントと混和材の和に対して０．０３〜０．０９重量％（メーカー指定量の１〜３倍）のＡＥ剤
ｂ……ポリカルボン酸塩系の高性能ＡＥ減水剤と、空気量が８〜１０％になる量のＡＥ助剤
実験Ｎo.３−２１で用いた高性能ＡＥ減水剤の使用量は、メーカー指定量である。（表中★印）
実験Ｎo.３−０６は加圧成形で行った（表中※印）。その他は振動成形。
【００３３】
【表４】

【表５】

【００３４】
表４及び表５より、他の条件を一定にして無水石こうの配合量を多くしていくと圧縮強度も次第に増大するが、セメント１００重量部に対し２重量部から効果が認められ、１５重量部を越えて添加してもそれ以上の強度増加は期待し難いことが判明した。
同様に、活性シリカとしてシリカフュームを配合した場合、３重量部より効果が認められ３０重量部を越えて添加してもそれ以上の強度増加は期待し難い。
アルミノケイ酸質の粘土の焼成物であるメタカオリンの場合は、５重量部より効果が認められ、２０重量部を越えて添加してもそれ以上の強度増加は期待し難い。また、それぞれを組合わせた場合は単独で添加した場合よりも高い圧縮強度を発現する。
【００３５】
更に、水／結合材（セメント＋混和材）比率を一定にして減水剤の添加量によりフロー値を変えた場合、フロー値が３００ｍｍを越えると吸水率が３０％を越え、耐凍害性の低下が予想される。フロー値が１１０ｍｍの場合、加圧成形では問題ないが、振動成形では巻き込んだ空気が抜けずに強度低下を来している。
以上より、本発明の吸水性セメント硬化体の製造においては、モルタルフロー値は１２０〜３００ｍｍであり、より好ましくは１４０〜２５０ｍｍである。高性能ＡＥ減水剤を添加する場合は、メーカー指定の上限の２倍程度までは遅延性の影響を大きく受け難いことも理解される。（実験Ｎo.３−21〜３−23参照）
【００３６】
実施例４
表４の実験Ｎo.３−１１の配合に、表６に示した量のギ酸カルシウム（試薬イ）及びチオシアン酸カルシウム（試薬ロ）を添加し、実施例１と同様に練混ぜ、圧縮強度測定用と吸水率測定用の供試体を同様にして形成した。５時間前養生をした後、１５度／時間の速度で２０℃から８５℃まで上げ、そのまま４時間保持して養生槽から取出し、１時間冷却後の脱型時強度と脱型後２０℃の室内で１４日間養生したときの圧縮強度及び吸水率を測定し、その結果を表６に併記した。
【００３７】
表６より、促進剤は（セメント＋混和材）に対して０．２重量％以上添加した場合に脱型強度の増加が認められるが、２重量％を越えると脱型後の強度の伸びが低下することが理解される。
【００３８】
【表６】

【００３９】
【発明の効果】
本発明により、セメント組成物中に大量の土を配合することが可能になり、得られた吸水性セメント硬化体は、水をかけると数秒〜数分の速さで吸水して水分をそのまま保持するので、特定の場所に従来のコンクリートに代えて使用すると藻や苔が自然に育成し、植生効果も発揮して環境を改善する。また、本発明の吸水性セメント硬化体の表面に触れた場合は人肌にしっとりとした優しい感触を与える。更に、本発明の吸水性セメント硬化体は通常の土、建設発生土を大量にセメントに混合して得られるため、建設発生土の有効利用にもなる。[0001]
[Technical field to which the invention belongs]
The present invention relates to a hardened water-absorbing cement and a method for producing the same, in which algae and moss are naturally grown on the surface and give a human-friendly feel.
[0002]
[Prior art]
Conventionally, the water absorption rate of cement hardened bodies such as mortar and concrete having a compressive strength of 10 to 60 N / mm ² is at most 4 to 6%, its water absorption rate is slow, and basically impermeable solid. It is a hardened body. Therefore, when concrete aesthetic measures are taken from the environmental aspect, as seen in vegetation blocks, etc., a concrete having a continuous space in which plants can be rooted is prepared, and soil is put in the space to add plants and their species. Measures such as artificial planting were taken.
On the other hand, the construction generated soil is a preferable material for landfilling at the final disposal site, but other wastes that contaminate groundwater are discarded together with the final disposal site. Therefore, there is a problem that the construction of the final disposal site does not remain and it is difficult to dispose of a large amount of construction generated soil.
[0003]
Japanese Patent Application No. 10-135106 proposed a solidifying material containing cement, gypsum, silica fume, and the like, and a sludge solidifying method using the same, with a particle size of 44 μm or less. This proposal basically mixes solidified material, sludge, fine aggregate, and coarse aggregate using the moisture in the sludge, and is intended for solidifying only sludge of 44 μm or less. It is intended for use, and no consideration is given to the improvement of water absorption, the growth of algae and moss, and the vegetation effect.
JP-A-9-142898 and JP-A-9-132440 also propose non-fired hardened bodies having a texture of soil and high strength and water absorption, but this proposal is based on clay and slaked lime and / or Or it mix | blends quicklime and autoclave curing is carried out, Autoclave curing has the problem that freeze-thaw durability is inferior.
[0004]
[Problems to be solved by the invention]
Therefore, the hardened cement body that can improve the freezing and thawing durability using normal room temperature or steam curing instead of autoclave curing, and can prepare an environment for natural growth of algae and moss on the hardened cement surface, is treated. Therefore, there is a need for a technology that can be used to make effective use of the soil generated by construction.
[0005]
[Means for Solving the Problems]
The object of the present invention is to solve the above-mentioned problems, and the composition thereof is a molding having a water absorption of 10 to 30% obtained by kneading cement, earth and water and by vibration molding, pressure molding or vibration pressure molding. a cured product, as the soil, 44 .mu.m or less of fine fraction content in absolute dry condition is 5 to 30 wt%, using the general knowledge on soil was added admixture to cement or cement total: Sat The weight ratio of the mixture is 1: 1 to 1: 4, and the weight ratio of water / cement weight ratio or water / (total amount of admixture mixed with cement) is 1.2 or less, and the admixture is clay. It is at least one of a calcined powder of mineral, gypsum and activated silica.
[0006]
The water-absorbent cement cured body of the present invention absorbs water at a speed of several seconds to several minutes when water is applied, and retains moisture as it is. Therefore, when used in place of conventional concrete, algae and moss grow naturally, exhibiting vegetation effects and improving the environment. Moreover, when the surface of the hardened water-absorbent cement of the present invention is touched, it gives a moist and gentle touch to human skin. Furthermore, the temperature of a conventional concrete structure once heated by solar heat or the like is difficult to cool, but the hardened water-absorbent cement of the present invention does not easily rise in temperature. It is effective and can maintain an excellent environment. Furthermore, since the hardened water-absorbent cement of the present invention can be obtained by mixing a large amount of ordinary soil and construction generated soil with cement, it can also be used effectively for construction generated soil.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The cement used in the present invention is usually various types of Portland cements such as early strength, very early strength, white color, moderate heat, low heat generation and sulfate resistant cement; various mixed cements mixed with silica powder, fly ash, blast furnace slag, etc .; It is a quick-hardening cement that is hardened by the formation of ettringite, and alumina cement is not preferred.
[0008]
The soil used in the present invention is a common sense soil, and red soil, ocher soil, black soil, white soil and the like can be used. Although construction-generated soil is basically desirable, it can be used even if it is naturally produced. The construction generated soil includes soil excavated by various constructions such as building construction such as buildings, tunnel construction, river and coastal revetment, road construction and restoration.
Soil having a fine particle content of 44 μm or less is preferably 5 to 30% by weight. The fine particle size of 44 μm or less is a particle passing through a JIS standard test sieve of 350 mesh and a nominal size of 44 μm , measured in an absolutely dry state in which the soil is dried at 110 ° C. for 24 hours. When the obtained soil is out of this range, it can be adjusted and used by mixing a soil with a large amount of fine particles and a soil with a small amount of fine particles.
If the fine particle content is less than 5% by weight, it is difficult to obtain a hardened cement with a water absorption of 10% or more even if the soil content is large. If the fine particle content exceeds 30% by weight, it is practical even if the soil content is reduced. Even if a sufficient strength is not obtained or the water absorption exceeds 30% by weight and a proper amount of air is entrained, the frost damage resistance is lowered, which is not preferable.
[0009]
Although the hardened cement of the present invention is basically a hardened mortar, it is a problem if it is up to 20% by weight even when gravel (coarse aggregate) having a diameter of more than 5 mm is mixed in the soil in a completely dry state. However, if the amount exceeds this, the water absorption rate is lowered, which is not preferable. The maximum diameter of the coarse aggregate that can be used is 25 mm.
[0010]
In the present invention, the water absorption of the cured product is 10 to 30%, preferably 15 to 25%. Here, the water absorption is the weight (A) measured when a cylindrical cured body having a diameter of 5 cm and a length of 10 cm is immersed in water at 20 ° C. for 24 hours to be saturated and measured at 105 ° C. for 24 hours. The weight (B) when dried is measured and expressed as 100 (A-B) / B (%).
If the water absorption is less than 10%, it is difficult to grow algae or moss, and if it exceeds 30%, it is difficult to obtain a practical strength of 10 N / mm ² or more, and the freeze-thaw durability is also unfavorable.
[0011]
In the present invention, cement is used as a binder. In order to increase the strength of the cement, components other than cement described later are blended, and this component is distinguished from cement as an admixture. Thus, the binder refers to cement alone or a blend of cement and admixture. The weight ratio of binder: soil is 1: 1 to 1: 4. Note that soil is calculated as absolutely dry. When the blending ratio of the binder and the soil is less than 1: 1, it is difficult to obtain a hardened cement body having a water absorption rate of 10% by weight or more even when the fine particle content passing through the sieve having a nominal diameter of 44 μm is 5% by weight or more. On the other hand, when the ratio exceeds 1: 4, a practical strength of 10 N / mm ² or more cannot be obtained, or even if a practical strength and an appropriate water absorption rate are obtained, the freeze-thaw durability is lowered.
[0012]
In the present invention, the water / binder ratio is 1.2 or less, preferably 1.0 to 0.45. If it exceeds 1.2, a practical strength of 10 N / mm ² or more cannot be obtained when there are many fine particles. If it is less than 0.45, the strength becomes too high and the water absorption rate does not become 10% by weight or more, and natural growth effects such as algae and moss cannot be obtained.
The water / binding material ratio of the present invention is a value when the soil is completely dried or converted into a completely dried state, and includes the amount of water absorbed by the soil.
[0013]
Further, the softness is preferably a mortar flow value according to JIS R 5201 of 300 mm or less. When the flow value exceeds 300 mm, the setting delay becomes large, and cracks due to thermal expansion are likely to occur when producing by steam curing. Moreover, since the kneaded material of this invention becomes strong, there exists a preferable flow value by a shaping | molding method, and the more preferable flow value in the case of shape | molding by vibration molding is 120-250 mm. When it is less than 120 mm, extrusion molding or pressure molding is preferably performed.
[0014]
In the present invention, one or more of calcined clay mineral powder, gypsum, and active silica are used as an admixture component that increases strength without significantly changing the water absorption rate. These have the effect of increasing strength even when used alone, but higher strength can be obtained when used in combination.
[0015]
The calcined powder of clay mineral is obtained by calcining clay containing alumina silicate as a main component at 600 to 1000 ° C. and is represented by metakaolin. Whether used alone or in combination with other admixtures, it is 20 parts by weight or less, preferably 5 to 15 parts by weight, based on 100 parts by weight of cement. If the amount is less than 5 parts by weight, the strength enhancement effect is small, and even if the amount exceeds 20 parts by weight, the strength enhancement effect is stagnant.
[0016]
Whether used alone or in combination with other admixtures, gypsum is 15 parts by weight or less, preferably 2 to 10 parts by weight, based on 100 parts by weight of cement in terms of anhydride. If the amount is less than 2 parts by weight, the strength enhancement effect is small, and even if the amount exceeds 15 parts by weight, the strength enhancement effect is stagnant, which is not preferable. The type of gypsum is not particularly limited, but it is preferably type II anhydrous gypsum called insoluble or hardly soluble anhydrous gypsum, and the fineness may be 3000 cm ² / g or more.
[0017]
Activated silica is mainly composed of amorphous SiO ₂ such as silica fume, silicified wood, firewood ash, and aerosil. Whether used alone or in combination with other admixtures, the active silica is 30 parts by weight or less, preferably 3 to 25 parts by weight, based on 100 parts by weight of cement. If the amount is less than 3 parts by weight, the strength enhancement effect is small, and even if the amount exceeds 30 parts by weight, the strength enhancement effect is stagnant.
[0018]
In the present invention, it is preferable to use a water reducing agent. As a kind of water reducing agent, a general water reducing agent having a low water reducing rate such as lignin sulfonate, carboxylate, polyol, etc., which is reduced to about 10% of the unit water volume in ordinary concrete; A blended AE water reducing agent; in ordinary concrete, there are a high performance water reducing agent and a high performance AE water reducing agent that reduce 20 to 30% of the unit amount, and among them, a high performance water reducing agent and a high performance AE water reducing agent are preferable. General water reducing agents and AE water reducing agents are added up to about twice the amount specified by the manufacturer.
High performance water reducing agents include polyalkylallyl sulfonates and melamine resin sulfonates, and even if they are added in a relatively large amount, there is no delay or air entrainment and the water reduction rate increases according to the amount added. It has the characteristic. Representative commercial product names include “Mighty 150” manufactured by Kao Corporation, “FT-500” manufactured by Grace Chemicals, “Sunflow PS” manufactured by Nippon Paper Industries Co., Ltd., and the like. These are added at most 3.0 parts by weight in terms of solid content with respect to 100 parts by weight of cement. Even if added over 3.0 parts by weight, the elongation of the water reduction rate is small.
[0019]
A high-performance water reducing agent does not have air entrainment, but it also provides air entrainment with the use of an AE agent to improve frost resistance.
The high-performance AE water reducing agent is a so-called polycarboxylate-based water reducing agent, and has air-entraining properties, thus improving the frost damage resistance and improving the water reduction rate according to the amount added, but also has a retarding property. growing. Therefore, in the case of a high-performance AE water reducing agent, the amount is at most twice the amount specified by the manufacturer with respect to 100 parts by weight of the binder. If the amount exceeds 2 times, the retardability becomes too large and cracking due to thermal expansion is likely to occur when steam curing or the like is performed. The brand names of commercially available high-performance AE water reducing agents include “Leo Build PS8 Series” manufactured by MMB, “Palic Series” manufactured by Fujisawa Pharmaceutical, and “Darlex Super Series” manufactured by Grace Chemicals. It is done.
[0020]
In the present invention, it is preferable to use appropriate amounts of various promoters because the pre-curing time and the time required to obtain the demolding strength can be shortened. Although it does not specifically limit as a promoter, Formic acid, calcium of nitric acid, magnesium, sodium, potassium salt, calcium of thiocyanate, magnesium, sodium, potassium salt, aluminum sulfate, etc. are preferable.
These accelerators are added in an amount of at most 2% by weight, preferably 0.2 to 1.5%, based on the binder (cement + admixture). Elongation is suppressed.
[0021]
In the production of the water-absorbent cement cured body, the main component can be kneaded using a normal mortar mixer or concrete mixer. More preferably, 70 to 80% of the total amount of water is added as primary water to cement, soil, admixture and other additives using a forced kneading mixer, and after the primary mixing for 1 to 3 minutes, the remaining 20 Add ~ 30% as secondary water and mix for several minutes. Molding method other vibration molding using a conventional external or internal vibrator, depending mortar flow value as described above, pressure forming is effected by the vibration pressing.
[0022]
The curing method is not particularly limited, and may be room temperature, but when producing as a precast product, atmospheric steam curing is preferable in terms of production efficiency. However, autoclave curing is not preferable because even if an appropriate amount of air is entrained, fine cracks enter the cured body during cooling, and even if the strength is high, freeze-thaw durability is poor.
When normal pressure steam curing is performed, the mixture is poured into a mold and then cured at a temperature of 40 to 100 ° C. after a precuring time.
[0023]
【Example】
Example 1
The following 7 types of soil were collected.
a Locally generated soil: 3% by weight of fine particles of 44 μm or less, gray black soil b Locally generated soil: 7% by weight of fine particles of 44 μm or less, Black soil c Locally generated soil: 13% by weight of fine particles of 44 μm or less, red soil d Locally-occurring soil: Containing 16% by weight of fine particles of 44 μm or less, loess e Locally-occurring soil: containing 24% by weight of fine particles of 44 μm or less; Soil: The following seven types of test soils were prepared by blending the grayish white soils a to f containing 35% by weight of fine particles having a particle size of 44 μm or less so that the content of fine particles having a particle size of 44 μm or less was a good value.
A: a Locally generated soil (3% by weight of fine particles of 44 μm or less, absolute dry specific gravity 2.61)
B: Mixture of locally produced soil and A (fine particles 5% by weight of 44 μm or less, absolute dry specific gravity 2.58)
C: c Mixture of locally produced soil and B (10% by weight of fine particles of 44 μm or less, absolutely dry specific gravity 2.40)
D: d Locally generated soil and C mixture (15% by weight of fine particles of 44 μm or less, absolutely dry specific gravity 2.35)
E: Mixture of e-produced soil and D (20% by weight of fine particles less than 44 μm, absolute dry density 2.13)
F: f A mixture of locally produced soil and E (fine content of 44% or less, 30% by weight, absolutely dry specific gravity 2.01)
G: g Locally generated soil (35% by weight of fine particles of 44 μm or less, absolute dry specific gravity 2.01)
[0024]
The types and amounts of soil shown in Tables 1 and 2 (converted to an absolutely dry state) are mixed with the amount of cement and water shown in Tables 1 and 2 with a planetary forced kneading mixer, and the flow value of the mortar is determined according to JIS. It was measured by R 5201 and listed in Table 1 and Table 2 together. As the water reducing agent, lignin sulfonic acid-based general AE water reducing agent was added to the cement as a solid content of 0.25% (amount specified by the manufacturer). For kneading, 80% of the total amount of water was added to ordinary Portland cement and soil, and primary kneading was conducted for 3 minutes, and then the remaining 20% of water was added and secondary kneading was conducted for 3 minutes. Using the obtained mortar, three specimens with a diameter of 10 cm and a length of 20 cm were used for measuring the compressive strength, and three specimens with a diameter of 5 cm and a length of 10 cm were used for measuring the water absorption, for measuring the growth state of moss. 3 pieces of 10 × 10 × 40 cm specimens were each formed on a shaking table, and after 5 hours of pre-curing, the temperature was raised from 20 ° C. to 85 ° C. at a rate of 15 ° C./hour and held for 4 hours until the next day. Slow cooling to demold. The compressive strength was measured after indoor curing for 14 days at 20 ° C. and a relative humidity of 80%. The moss was grown in a stream flowing through the forest. The moss generation and the growth state after 6 months were observed on the edge of a river where water was not directly applied. The moss growing state was evaluated according to the following criteria.
× …… No occurrence at all Δ …… Growth on the side portion ○ …… Growth also on the side portion and part of the surface portion where the sun leaks ◎ …… Growth on the entire surface These results are shown in Table 1 and Table 2 together.
[0025]
[Table 1]

[Table 2]

[0026]
The following facts can be understood from Tables 1 and 2. That is, when the fine particle content in the soil is less than 5% by weight, even if the mixing ratio of the soil to the cement is 1: 4, the water absorption is less than 10% by weight and there is no natural growth of moss. When the fine particle content is 5% by weight, the water absorption can exceed 10% by setting the mixing ratio to 1: 1 and the water / cement ratio to 0.45. In order to obtain the same flow value, the larger the blending ratio of soil and the higher the content of fine particles, the higher the water / cement ratio and the lower the compressive strength, but the higher the water absorption. In the scope of the present invention, in Experiment No. 1-23, which has the largest amount of fine particles and the highest blending ratio of soil, the water / cement ratio for achieving a practical strength of 10 N / mm ² or more was 1.20. It was.
[0027]
When the fine particle content exceeds 30% by weight, a compressive strength of 10 N / mm ² or more cannot be obtained even when the blending ratio is 1: 1 and the water / cement ratio is 1 or less. It shows that it is greatly influenced by the content of fine particles.
As for the natural growth state of the moss, the water absorption is preferably 10% or more and 15% or more, and grows better as the water absorption increases. When the water absorption rate is 30%, the strength is barely 10 N / mm ² or more, and a more preferable upper limit of the water absorption rate is considered to be around 25% considering the balance of strength.
[0028]
Example 2
Experiment No. 1-01 to 1-07 and 1-20 to 1-23 of Example 1 were molded in the same manner as in Example 1, steam-cured, and standard-cured for 14 days to be 10 × 10 × 40 cm. A specimen was obtained. Using this, a freeze-thaw test was conducted according to ASTM C666 (rapid freezing in water, thawing in water), and the relative kinematic modulus at 300 cycles was measured. The results are shown in Table 3.
[0029]
As is clear from Table 3, the kinematic elastic modulus gradually decreases as the ratio of soil to cement increases. However, when the ratio of cement: soil exceeds 1: 4, it rapidly decreases and reaches 60% or less. The frost damage is also expected to deteriorate. In addition, even if the cement: soil mixing ratio is the same, the soil having a large amount of fine particles tends to have a relatively low relative elastic modulus.
[0030]
[Table 3]

[0031]
Example 3
For 100 parts by weight of ordinary Portland cement of Example 1, natural anhydrous gypsum (type II, fineness 4500 cm ² / g), silica fume (fineness 22 m ² / g), metakaolin (fineness 8500 cm ² / g) as admixtures. Were mixed at the ratios shown in Tables 4 and 5, the mixing ratio of the binder (cement + admixture) and soil was 1: 2.5, and after mixing in the same manner as in Example 1, the flow value was measured. . A specimen similar to Example 1 was prepared and cured by the same curing method, and the compressive strength and the water absorption rate are shown in Tables 4 and 5.
When the flow value was 120 mm or more, vibration molding was performed using a vibration table, and when the flow value was less than 120 mm, pressure molding was performed with a pressure of 0.4 N / mm ² .
[0032]
In Experiment No. 3-13, the implantation surface of the test piece was thermally expanded and expanded several mm, and fine cracks were formed throughout. In Experiment No. 3-23, the cracked surface was not visible, but the driving surface was slightly swollen. (* In the table)
As the water reducing agent, the following a and b were added in the amounts shown in Tables 4 and 5 in terms of solid content.
a …… Naphthalenesulfonate-based high-performance water reducing agent and 0.03-0.09% by weight (1 to 3 times the manufacturer's specified amount) of AE agent based on the sum of cement and admixture b …… Polyester The amount of the high-performance AE water reducing agent used in the carboxylate-based high-performance AE water reducing agent and the high-performance AE water reducing agent used in the AE auxiliary experiment No. 3-21 in which the air amount is 8 to 10% is a manufacturer-specified amount. . (★ mark in the table)
Experiment No. 3-06 was performed by pressure molding (* mark in the table). Others are vibration molding.
[0033]
[Table 4]

[Table 5]

[0034]
From Tables 4 and 5, the compression strength increases gradually as the amount of anhydrous gypsum increases with other conditions constant, but the effect is recognized from 2 parts by weight with respect to 100 parts by weight of cement. It was found that it was difficult to expect any further increase in strength even when added beyond the part.
Similarly, when silica fume is blended as active silica, an effect is recognized from 3 parts by weight, and even if it is added in an amount exceeding 30 parts by weight, it is difficult to expect a further increase in strength.
In the case of metakaolin, which is a calcined product of aluminosilicate clay, an effect is recognized from 5 parts by weight, and even if it is added in excess of 20 parts by weight, no further increase in strength is expected. Moreover, when each is combined, a higher compressive strength is exhibited than when added alone.
[0035]
Furthermore, when the flow value is changed by adding the water reducing agent while keeping the water / binding material (cement + admixture) ratio constant, if the flow value exceeds 300 mm, the water absorption exceeds 30% and the frost damage resistance is reduced. Is expected. When the flow value is 110 mm, there is no problem in the pressure molding, but in the vibration molding, the entrained air does not escape and the strength is reduced.
As mentioned above, in manufacture of the water absorbing cement hardening body of this invention, a mortar flow value is 120-300 mm, More preferably, it is 140-250 mm. It is also understood that when a high-performance AE water reducing agent is added, it is hardly affected by the delay property up to about twice the upper limit specified by the manufacturer. (See Experiment Nos. 3-21 to 3-23)
[0036]
Example 4
Calcium formate (reagent A) and calcium thiocyanate (reagent B) in the amounts shown in Table 6 were added to the formulation of Experiment No. 3-11 in Table 4 and mixed in the same manner as in Example 1 to measure the compressive strength. Samples for measuring water absorption and water absorption were formed in the same manner. After pre-curing for 5 hours, increase the temperature from 20 ° C. to 85 ° C. at a rate of 15 degrees / hour, hold it for 4 hours, remove it from the curing tank, and remove the strength at the time of demolding after cooling for 1 hour and 20 ° C. The compressive strength and water absorption rate were measured when cured indoors for 14 days, and the results are also shown in Table 6.
[0037]
From Table 6, an increase in the demolding strength is observed when the accelerator is added in an amount of 0.2% by weight or more based on (cement + admixture). It is understood that it decreases.
[0038]
[Table 6]

[0039]
【The invention's effect】
According to the present invention, it becomes possible to mix a large amount of soil in a cement composition, and the obtained water-absorbent cement cured body absorbs water at a speed of several seconds to several minutes when water is applied, and retains moisture as it is. Therefore, algae and moss grow naturally when used instead of conventional concrete in a specific place, and the vegetation effect is also exhibited to improve the environment. Moreover, when the surface of the hardened water-absorbent cement of the present invention is touched, it gives a moist and gentle touch to human skin. Furthermore, since the hardened water-absorbent cement of the present invention can be obtained by mixing a large amount of ordinary soil and construction generated soil with cement, it can also be used effectively for construction generated soil.

Claims

A molded hardened body having a water absorption of 10 to 30% obtained by kneading cement, earth and water and vibration molding, pressure molding or vibration pressure molding, and having a fine particle of 44 μm or less in an absolutely dry state as soil A common sense soil having a content of 5 to 30% by weight is used, and the cement weight: soil weight ratio is 1: 1 to 1: 4, and the water / cement weight ratio is 1.2. A water-absorbent cement-molded cured body characterized by the following:

Cement, soil, admixture and water are kneaded and vibration-molded, pressure-molded or molded by vibration-molding. The molded hardened body has a water absorption of 10 to 30%. The following fine particle content is 5 to 30% by weight, using common-sense soil, the total amount of admixture added to cement: the weight blending ratio of soil is 1: 1 to 1: 4, A water- absorbent cement-molded cured product, wherein a weight ratio of water / (total amount of admixture mixed with cement) is 1.2 or less .

The water-absorbent cement-molded cured product according to claim 2, wherein the admixture is at least one of a calcined powder of clay mineral, gypsum and activated silica.

A method for producing a water-absorbing cement-molded cured body having a water absorption rate of 10 to 30% by adding water and kneading to cement and general common soil and molding by vibration molding, pressure molding or vibration pressure molding , Using soil with a dry particle content of 44 μm or less having a fine particle content of 5 to 30% by weight , the total cement amount: the weight ratio of soil being 1: 1 to 1: 4, and the water / cement weight ratio Is 1.2 or less, The manufacturing method of the water-absorbing-cement molding hardening body characterized by the above-mentioned.

Water is added to and mixed with cement, admixture, and common sense soil, and molded by vibration molding, pressure molding, or vibration pressure molding to produce a water-absorbent cement molded cured body with a water absorption of 10 to 30%. In the method, the soil having a fine particle content of 44 μm or less in an absolutely dry state is 5 to 30% by weight, the total amount of cement and admixture: the weight ratio of the soil is 1: 1 to 1: 4, and A method for producing a water-absorbing cement-molded and cured body, wherein a weight ratio of water / (total amount of admixture added to cement) is 1.2 or less.

6. The process for producing a water-absorbing cement-molded and cured body according to claim 5, wherein the admixture is at least one of a calcined powder of clay mineral, gypsum and activated silica.