JP3839698B2

JP3839698B2 - High tough nonwoven fabric mat for hydraulic material reinforcement

Info

Publication number: JP3839698B2
Application number: JP2001322441A
Authority: JP
Inventors: 健次松本; 俊次倉橋; 秀樹保城
Original assignee: Kuraray Co Ltd
Current assignee: Kuraray Co Ltd
Priority date: 2001-10-19
Filing date: 2001-10-19
Publication date: 2006-11-01
Anticipated expiration: 2021-10-19
Also published as: JP2003128447A

Description

【０００１】
【発明の属する技術分野】
本発明は、脆性物であるセメント等の水硬性物質の補修・補強の補強材として用いることにより、施工が簡単で、セメント等の水硬性物質をより強固、より高靭性にすることができる水硬性物質補強用高靭性不織布マットに関するものである。
【０００２】
【従来の技術】
ポルトランドセメントで代表される水硬性物質からなる水硬性硬化物は、圧縮強度が強く不燃で耐久性があり、安価なため土木建築用途に大量に使用されているが、得られる水硬性硬化物は引っ張り強力が弱いので、その補強材として鉄筋が一般的に使用されている。しかし鉄筋補強水硬性硬化物は構造的には鉄筋の被り厚さが必要であるが、この被り部分が近年水硬性硬化物の塩害・中性化により脆弱となり、水硬性硬化物片の剥離剥落事故が多発する現象が多々発生するため、早急な対策が求められている。
【０００３】
従来、コンクリート等の水硬性物質からなる水硬性硬化物を補修・補強する方法としては、具体的には、水硬性硬化物の不良箇所をウォータージェット等にて撤去し、その上面をポリマー系の高強度コンクリートやモルタルを吹き付ける工法や、鋼板を貼り付ける工法、短繊維混入コンクリートやモルタルを吹き付ける工法、一部アラミド繊維、ガラス繊維、ポリビニルアルコール系繊維等で作成したシートを合成樹脂を用いて貼り付ける工法、あるいは光硬化性樹脂を貼り付ける工法等が開発され、また一部実施されている。
【０００４】
しかしながら、鋼板を貼り付ける工法の場合、初期性能は確保できるが、重量が大となるため設備が大がかりとなり施工性が悪く、またポリマー系のコンクリートやモルタルを吹き付ける工法では何れも材料が非常に高価となり、経済性が悪い等の問題がある。一方、短繊維混入コンクリートやモルタルを補修面に直接吹き付ける工法は、短繊維により引っ張り応力が伝達されるので有用な工法であるが、一定量以上の繊維をコンクリートに混入した場合、流動性が非常に低下するためミキサー車よりの排出、コンクリートポンプによるポンプ圧送等が困難になり、そのため吹き付け施工が困難となる場合がある。また繊維混入による吹き付けの場合、マトリクス中に繊維が偏在する事があり、均一な品質の補強層が得られない場合がある。
【０００５】
【発明が解決しようとする課題】
本発明者等は、上記の課題を解決するために鋭意努力した結果、繊維物性の異なる有機合成繊維Ａおよび有機合成繊維Ｂで構成され、所定の嵩比重をもった不織布マットを剥落補修個所に型枠を介して取付け、該不織布マットにセメント等の水硬性物質を注入して含浸させ、硬化させることによりコンクリート等の水硬性硬化物が高強度、高靭性となり、かつ施工性が格段に向上することを見出した。本発明の水硬性物質補強用高靭性不織布マットは本発明者らが開発した特公平８―１１７０６号公報記載の不織布を更に改良しており、コンクリート等水硬性物質の補強材として用いた場合、得られる水硬性硬化物は、ひび割れ発生直後の強度の低下がなく、かつ破壊強度が初期クラック強度よりも大きく、しかも品質が均一な高靭性補強層からなる。
【０００６】
【課題を解決するための手段】
本発明は、ひび割れ発生直後の強度の低下がなく、品質が均一で施工性・経済性に優れたコンクリート等水硬性物質の補修・補強に用いる水硬性物質補強用高靭性不織布マット（以下、高靭性不織布マットと略す）に関するものである。
すなわち本発明は、以下の１）、２）の条件を満足する有機合成繊維Ａおよび有機合成繊維Ｂからなり、該有機合成繊維Ａと該有機合成繊維Ｂの割合が重量比でＡ：Ｂ＝８０：２０〜２０：８０で構成され、嵩比重が０．００８〜０．０１８ｇ／cm^３である水硬性硬化物の補修・補強に用いる不織布マットであって、該不織布マットを含有した水硬性硬化物の破壊強度が初期クラック強度よりも大きいことを特徴とする水硬性物質補強用高靭性不織布マットである。
１）有機合成繊維Ａは、繊維繊度８０〜１５０ｄｔｅｘ、かつ破断伸度１０％以下であり、有機合成繊維Ａを単独で含有して得られる水硬性硬化物の破壊強度と初期クラック強度の関係が、破壊強度＞初期クラック強度であること、
２）有機合成繊維Ｂは、繊維繊度３００〜５００ｄｔｅｘ、かつ破断伸度７％以下であり、有機合成繊維Ｂを単独で含有して得られる水硬性硬化物の破壊強度と初期クラック強度の関係が、破壊強度＜初期クラック強度であること、
そして本発明は、好ましくは有機合成繊維Ａおよび有機合成繊維Ｂがポリビニルアルコール系繊維、ポリオレフィン系繊維、ポリアミド系繊維、ポリエステル系繊維のうちいずれかである、上記の高靭性不織布マットに関する。
【０００７】
本発明の高靭性不織布マットは、繊維物性の異なる有機合成繊維Ａおよび有機合成繊維Ｂからなり、該有機合成繊維Ａ、Ｂが重量比でＡ：Ｂ＝８０：２０〜２０：８０、嵩比重が０．００８〜０．０１８ｇ／cm^３の範囲で構成されていることが必要である。有機合成繊維Ａの割合が８０パーセントを越えると、得られた不織布の嵩比重が大きくなり、セメントミルクの含浸性が問題となり施工性に問題を残す。一方、有機合成繊維Ａの割合が２０パーセント未満となると得られる水硬性硬化物の破壊強度が初期クラック強度より向上せず、目的とする高靭性の性能が得られない。好ましくはＡ：Ｂ＝７０：３０〜３０：７０、より好ましくは６０：４０〜４０：６０の範囲である。
【０００８】
また、本発明の高靭性不織布マットの嵩比重が０．００８ｇ／cm^３より小さい場合、不織布の密度が疎になり過ぎて、水硬性物質に占める割合が小さくなり、補強効果が得られない。一方、嵩比重が０．０１８ｇ／cm^３より大きい場合、セメントミルクの含浸性が問題となり施工性に問題が生じる。好ましくは、０.０１０〜０．０１５ｇ／cm^３の範囲である。
【０００９】
次に、本発明の高靭性不織布マットを構成する有機合成繊維Ａ、有機合成繊維Ｂについて、以下詳細に説明する。
まず、有機合成繊維Ａは、繊維繊度８０〜１５０ｄｔｅｘ、破断伸度１０％以下からなる繊維である必要がある。有機合成繊維Ａの繊維繊度が８０ｄｔｅｘより小さい場合、不織布マットの嵩比重が大きくなりセメントミルクの含浸性等施工性に問題を残す。また繊維繊度が１５０ｄｔｅｘより大きくなると、繊維本数が不足し高靭性が得られにくい。好ましくは１００〜１３０ｄｔｅｘである。さら繊維の破断伸度が１０％より大きくなると、得られる水硬性硬化物において、初期クラック発生後の応力の低下が大きく、たわみが増加しても応力が低下した状態なので靭性を確保できない。好ましくは８％以下３％以上である。
【００１０】
次に、有機合成繊維Ｂについてであるが、有機合成繊維Ｂの役割としては、有機合成繊維Ａを補完すること、すなわちセメントミルクの注入が可能となる嵩比重確保であり、具体的には、繊維繊度３００〜５００ｄｔｅｘ、破断伸度７％以下からなる繊維である。繊維繊度が３００ｄｔｅｘより小さい場合、不織布マットの嵩比重が大きくなりセメントミルクの含浸性等の施工性に問題を残す。また繊維繊度が５００ｄｔｅｘより大きくなると、繊維本数が不足し高靭性が得られにくい。好ましくは３５０〜４５０ｄｔｅｘである。さらに破断伸度が７％よりも大きくなると、初期クラック発生後の強度低下が顕著となる。好ましくは６％以下２％以上である。
【００１１】
また、有機合成繊維Ａは、繊維成分が有機合成繊維Ａのみ単独で含有された水硬性硬化物の破壊強度と初期クラック強度の関係が、破壊強度＞初期クラック強度になるような特徴を有していることが必要である。一方、有機合成繊維Ｂは、繊維成分が有機合成繊維Ｂのみ単独で含有された水硬性硬化物の破壊強度と初期クラック強度の関係が、破壊強度＜初期クラック強度になるような特徴を有していることが必要である。ここでいう初期クラック強度とは、水硬性硬化物の曲げ強度−たわみ曲線を作成したとき、曲げ強度とたわみが実質的に比例関係を有し、かつ最大のたわみを示すときの強度を示す。また破壊強度とは、水硬性硬化物が破壊したときの曲げ強度を示す。本発明の不織布は、上記したように初期クラック発生後の強度低下低減の役割を示す有機合成繊維Ａと、嵩比重確保を目的とする有機合成繊維Ｂの配合比を最適にすることにより高靭性のものが得られる。繊維で補強した水硬性物質が曲げ破壊された場合、繊維の破断伸度によりマトリクスに初期クラックが生じた後の曲げ強度−たわみ曲線の挙動が変わってくる。靭性を確保するためにはマトリクスに初期クラックが発生した後、直ちに繊維が応力を負担することが必要であり、本発明においては有機合成繊維Ａよりも破断伸度の低い有機合成繊維Ｂがその役割を分担しており、少し遅れて有機合成繊維Ｂよりも破断伸度の大きい有機合成繊維Ａが更に応力を分担することにより、その相乗効果で高靭性が確保することができるものである。ここで、繊維Ａの引張強度は好ましくは１０００Ｎ／mm^２以上、より好ましくは１１００Ｎ／mm^２以上であり、一方、繊維Ｂの引張強度は好ましくは８００Ｎ／mm^２以上、より好ましくは９００Ｎ／mm^２以上である。
【００１２】
本発明で使用する繊維としては、有機合成繊維の中でもポリビニルアルコール系繊維がセメント等の水硬性物質との接着性においてより望ましいが、繊維の種類は何ら制限されるものではなく、有機合成繊維、半合成繊維、人造繊維、無機繊維、それらの２種以上の併用等のいずれであってもよい。具体的にはポリエステル系繊維、ポリアミド系繊維、ポリオレフィン系繊維、アクリル系繊維等を挙げることができる。
【００１３】
本発明の不織布マットの製造方法としては、例えば本発明の重量比で構成された有機合成繊維Ａおよび有機合成繊維Ｂをあや振りエアーサッカー等を通じて移動する金網ネット上に供給し不織布を形成せしめた後、繊維どうしを固定するために接着剤処理をして乾燥熱処理すればよい。接着剤はスプレーで吹き付けても、また接着剤浴中に浸漬してもよい。嵩比重及び厚みの調整は繊維の繊度の選択、繊維長、給糸速度、ネット速度及び接着剤処理後のプレスによって調節できる。不織布マットの製造時に繊維どうしを固定するために使用する接着剤は、繊維の種類や単繊維の繊度によって接着性が異なるので、市販の接着剤の中から適宜選ぶのが好ましい。本発明で用いられる接着剤としては、ポリ酢酸ビニル系、メラミン系エチレン−酢酸ビニル共重合体、アクリル系、エポキシ系等の水系エマルジョンが接着性や作業性の面で好ましく用いられる。またポリビニルアルコールやその変性物等の水溶性高分子接着剤も使用できる。
【００１４】
本発明の高靭性不織布マットは土木用の客土や盛土等の土砂の補強や現場施工用セメントモルタル等の成型部材、トンネルや法面などのセメント吹付け工法へのセメント等のマトリックス保持材、ひび割れ防止材、及び補強材として用いることができる。
【００１５】
【実施例】
以下実施例によって、本発明を説明するが、本発明はこれら実施例により何等限定されるものではない。なお本発明の実施例において、ポリビニルアルコールの重合度、繊維繊度、繊維強度、破断伸度、不織布の嵩比重は以下の測定方法により測定されたものを意味する。
【００１６】
［ポリビニルアルコールの重合度］
ＪＩＳＫ６７２６に準拠して測定した。
【００１７】
［繊度ｄｔｅｘ］
得られた繊維状物の一定試長の重量を測定して見掛け繊度をｎ＝５以上で測定し、平均値を求めた。
【００１８】
［繊維強度Ｎ／mm^２、破断伸度％］
予め温度２０℃、相対湿度６５％の雰囲気下で２４時間繊維を放置して調湿したのち、単繊維を試長１０cm、引張速度５cm／分としてインストロン試験機「島津製作所製オートグラフ」にて繊維強度を測定した。伸度は、単繊維破断（cm）／把持長（cm）×１００により算出した。なお繊維長が１０cmより短い場合は、そのサンプルの可能な範囲での最大長さを把持長として測定することとした。
【００１９】
［不織布の嵩比重ｇ／cm^３］
不織布シートの重量をその占める見掛け体積で除した値を示した。
【００２０】
［実施例１〜３、比較例１〜５］
重合度１７００のポリビニルアルコールをジメチルスルホキシド（ＤＭＳＯ）中に溶解し、２０．７％とした紡糸原液を溶剤湿式紡糸して延伸熱処理し、繊維繊度が５０ｄｔｅｘ、繊維強度１０００Ｎ／mm^２、破断伸度８％、および繊維繊度１００ｄｔｅｘ、繊維強度１１００Ｎ／mm^２、破断伸度９％の２種類の繊維Ａのモノフィラメント繊維を得た。また重合度１７００のポリビニルアルコールを５０％の水溶液とした紡糸原液を常法により乾式紡糸して延伸熱処理し、繊維繊度４００ｄｔｅｘ、繊維強度８９０Ｎ／mm^２、破断伸度６％、および繊維繊度６００ｄｔｅｘ、繊維強度９２０Ｎ／mm^２、破断伸度５％の２種類の繊維Ｂのモノフィラメント繊維を得た。該モノフィラメント繊維を５インチの長さに各々カットし、それを引き揃えて縄状とし熱処理を施しそれを解繊する。更に解繊した嵩高性を持たせた繊維Ａ・Ｂを表１に示す割合にて混合しエアーブローにより幅１．２ｍのネット上に三次元立体勾配となるように給糸し、接着剤としてポリビニルアルコール樹脂水溶液をスプレー散布した後、厚さ５０mmに押さえて温度１５０℃で１０分間、乾燥熱処理して不織布を作成した。不織布マットの構成を表１に示す。
【００２１】
【表１】

【００２２】
得られた個々の不織布マットを幅１０cm、長さ４０cmに切断し、幅１０cm、長さ４０cm、高さ５cmの鋼製型枠に敷き、ポルトランドセメントを用いた水／セメント＝０．３５のセメントミルクを流し込み供試体を作成した。流し込みに際しては、均一性を保つため振動成形機を併用した。打設後室温２０℃、湿度６５％の室内に２４時間放置し脱型し、２８日間気中養生を行ない、繊維補強板を得た。養生完了後の供試体を島津製作所製のオートグラフを用い、三等分点載荷にて曲げ試験を実施した。その物性値の測定した結果を表２、曲げ強度−たわみ曲線を図１に示す。
【００２３】
比較例１、２の構成の不織布マットは嵩比重が大きいため、セメントミルク充填性が劣っていた。また比較例３〜５の構成の不織布マットは嵩比重が小さいため、セメントミルク充填性は問題なかったが、繊維補強板の破壊強度は初期クラック強度と同等かまたは破壊強度より小さく、高靭性が得られなかった。
一方、実施例１〜３の構成の不織布マットを用いた繊維補強板は比較例１〜５の不織布マットを用いた繊維補強板に比べて、セメントミルクの充填性に優れ、かつ破壊強度が初期クラック強度よりも大きく、良好な靭性が得られた。
【００２４】
【表２】

【００２５】
【発明の効果】
本発明の、繊維物性の異なる有機合成繊維Ａおよび有機合成繊維Ｂからなり、所定の嵩比重をもつ不織布マットを補強材として用いて得られる水硬性硬化物は、ひび割れ発生直後の強度の低下がなく、破壊強度が初期クラック強度よりも大きく、すなわち高靭性であり、かつ施工性が格段に向上する。その結果、品質が均一な高靭性補強層を得ることができる。
【００２６】
【図面の簡単な説明】
【図１】実施例１〜３および比較例１〜５で得られた成形物の曲げ強度−たわみ曲線を示す。
【符号の説明】
１：比較例１で得られた成形物の曲げ強度−たわみ曲線
２：比較例２で得られた成形物の曲げ強度−たわみ曲線
３：実施例１で得られた成形物の曲げ強度−たわみ曲線
４：実施例２で得られた成形物の曲げ強度−たわみ曲線
５：実施例３で得られた成形物の曲げ強度−たわみ曲線
６：比較例３で得られた成形物の曲げ強度−たわみ曲線
７：比較例４および比較例５で得られた成形物の曲げ強度−たわみ曲線[0001]
BACKGROUND OF THE INVENTION
The present invention can be used as a reinforcing material for repairing / reinforcing hydraulic materials such as cement, which is a brittle material, so that the construction is simple and the hydraulic materials such as cement can be made stronger and tougher. The present invention relates to a high-toughness nonwoven fabric mat for reinforcing hard materials.
[0002]
[Prior art]
Hydraulic cured products made of hydraulic materials such as Portland cement have high compressive strength, are non-flammable and durable, and are inexpensive and are used in large quantities for civil engineering and construction applications. Since tensile strength is weak, reinforcing bars are generally used as the reinforcing material. However, structurally, the reinforcing steel reinforced hydraulically-cured product requires a covering thickness of the reinforcing bar, but this covered part has become brittle in recent years due to salt damage and neutralization of the hydraulically-cured material, and the piece of hydraulic-cured material is peeled off. Since many accidents occur frequently, immediate countermeasures are required.
[0003]
Conventionally, as a method of repairing / reinforcing a hydraulic cured product made of a hydraulic substance such as concrete, specifically, a defective portion of the hydraulic cured product is removed with a water jet or the like, and the upper surface thereof is made of a polymer system. A method of spraying high-strength concrete or mortar, a method of pasting steel plates, a method of spraying concrete mixed with short fibers or mortar, and a sheet made of aramid fiber, glass fiber, polyvinyl alcohol fiber, etc. A method of attaching, a method of attaching a photocurable resin, and the like have been developed and implemented in part.
[0004]
However, in the case of the method of attaching steel sheets, the initial performance can be ensured, but because the weight is large, the equipment becomes large and the workability is poor, and in the methods of spraying polymer concrete or mortar, the materials are very expensive. There are problems such as poor economy. On the other hand, the method of spraying short fiber-mixed concrete or mortar directly onto the repair surface is a useful method because the tensile stress is transmitted by the short fiber, but if a certain amount of fiber is mixed into the concrete, the fluidity is extremely high. Therefore, it becomes difficult to discharge from the mixer truck, pumping with a concrete pump, and the like, and thus, spraying may be difficult. In addition, in the case of spraying due to fiber mixing, fibers may be unevenly distributed in the matrix, and a uniform quality reinforcing layer may not be obtained.
[0005]
[Problems to be solved by the invention]
As a result of diligent efforts to solve the above problems, the present inventors have made a nonwoven fabric mat composed of organic synthetic fibers A and organic synthetic fibers B having different fiber properties and having a predetermined bulk specific gravity as a repair repair site. Installed through a formwork, injecting and impregnating hydraulic materials such as cement into the non-woven mat, and curing it to make the hardened materials such as concrete high strength and toughness, and the workability is remarkably improved. I found out. The high-toughness nonwoven fabric mat for reinforcing a hydraulic material of the present invention is a further improvement of the nonwoven fabric described in Japanese Patent Publication No. 8-11706, which was developed by the present inventors. When used as a reinforcing material for a hydraulic material such as concrete, The obtained hydraulic cured product is composed of a high-toughness reinforcing layer that does not decrease in strength immediately after the occurrence of cracks, has a fracture strength greater than the initial crack strength, and has a uniform quality.
[0006]
[Means for Solving the Problems]
The present invention provides a high-toughness nonwoven fabric mat (hereinafter referred to as a high-toughness nonwoven fabric mat) for use in the repair and reinforcement of hydraulic materials such as concrete, which has no deterioration in strength immediately after the occurrence of cracks, has uniform quality, and is excellent in workability and economy. Abbreviated tough non-woven mat).
That is, the present invention comprises an organic synthetic fiber A and an organic synthetic fiber B that satisfy the following conditions 1) and 2), and the ratio of the organic synthetic fiber A and the organic synthetic fiber B is A: B = A non-woven mat used for repair and reinforcement of a hydraulic hardened material having a bulk specific gravity of 0.008 to 0.018 g / cm ³ and comprising 80:20 to 20:80, and containing the non-woven mat A high-toughness nonwoven fabric mat for reinforcing a hydraulic material, wherein the fracture strength of the cured product is greater than the initial crack strength.
1) The organic synthetic fiber A has a fiber fineness of 80 to 150 dtex and a breaking elongation of 10% or less, and there is a relationship between the fracture strength and the initial crack strength of a hydraulic cured product obtained by containing the organic synthetic fiber A alone. , Fracture strength> initial crack strength,
2) The organic synthetic fiber B has a fiber fineness of 300 to 500 dtex and a breaking elongation of 7% or less, and there is a relationship between the fracture strength and the initial crack strength of the hydraulic cured product obtained by containing the organic synthetic fiber B alone. , Fracture strength <initial crack strength,
And this invention relates to said high toughness nonwoven fabric mat | matte in which the organic synthetic fiber A and the organic synthetic fiber B are preferably any of polyvinyl alcohol fiber, polyolefin fiber, polyamide fiber, and polyester fiber.
[0007]
The high-toughness nonwoven fabric mat of the present invention comprises organic synthetic fibers A and organic synthetic fibers B having different fiber properties, and the organic synthetic fibers A and B are in a weight ratio of A: B = 80: 20 to 20:80, bulk specific gravity. Is required to be comprised in the range of 0.008 to 0.018 g / cm ³ . When the ratio of the organic synthetic fiber A exceeds 80%, the bulk specific gravity of the obtained non-woven fabric increases, and the impregnation property of cement milk becomes a problem, leaving a problem in workability. On the other hand, when the ratio of the organic synthetic fiber A is less than 20 percent, the fracture strength of the obtained hydraulic cured product is not improved from the initial crack strength, and the intended high toughness performance cannot be obtained. Preferably it is A: B = 70: 30-30: 70, More preferably, it is the range of 60: 40-40: 60.
[0008]
Further, when the bulk specific gravity of the high-toughness nonwoven fabric mat of the present invention is less than 0.008 g / cm ³ , the density of the nonwoven fabric becomes too sparse, and the proportion of the hydraulic material occupies less, so that the reinforcing effect cannot be obtained. On the other hand, when the bulk specific gravity is larger than 0.018 g / cm ³ , the impregnation property of cement milk becomes a problem and the workability is problematic. Preferably, the range is 0.010 to 0.015 g / cm ³ .
[0009]
Next, the organic synthetic fiber A and the organic synthetic fiber B constituting the high toughness nonwoven fabric mat of the present invention will be described in detail below.
First, the organic synthetic fiber A needs to be a fiber having a fiber fineness of 80 to 150 dtex and a breaking elongation of 10% or less. When the fiber fineness of the organic synthetic fiber A is less than 80 dtex, the bulk specific gravity of the nonwoven fabric mat becomes large, and problems remain in workability such as impregnation of cement milk. If the fiber fineness is greater than 150 dtex, the number of fibers is insufficient and high toughness is difficult to obtain. Preferably it is 100-130 dtex. Further, when the breaking elongation of the fiber is greater than 10%, the resulting hydraulic cured product has a large decrease in stress after the initial crack is generated, and the toughness cannot be secured because the stress is reduced even when the deflection is increased. Preferably, it is 8% or less and 3% or more.
[0010]
Next, as for the organic synthetic fiber B, the role of the organic synthetic fiber B is to supplement the organic synthetic fiber A, that is, to secure bulk specific gravity capable of injecting cement milk. Specifically, A fiber having a fiber fineness of 300 to 500 dtex and a breaking elongation of 7% or less. When the fiber fineness is less than 300 dtex, the bulk specific gravity of the nonwoven fabric mat becomes large, and problems remain in workability such as cement milk impregnation. If the fiber fineness is greater than 500 dtex, the number of fibers is insufficient and high toughness is difficult to obtain. Preferably it is 350-450 dtex. Further, when the elongation at break exceeds 7%, the strength drop after the occurrence of the initial crack becomes remarkable. Preferably, it is 6% or less and 2% or more.
[0011]
In addition, the organic synthetic fiber A has a characteristic that the relationship between the fracture strength and the initial crack strength of the hydraulic cured product containing only the organic synthetic fiber A alone as the fiber component is such that the fracture strength is greater than the initial crack strength. It is necessary to be. On the other hand, the organic synthetic fiber B is characterized in that the relationship between the breaking strength and the initial crack strength of the hydraulic cured product containing only the organic synthetic fiber B alone as the fiber component is such that the breaking strength <the initial crack strength. It is necessary to be. The initial crack strength here refers to the strength at which the bending strength and the deflection have a substantially proportional relationship and the maximum deflection is exhibited when a bending strength-deflection curve of the hydraulic cured product is created. The breaking strength indicates bending strength when the hydraulic cured product is broken. As described above, the nonwoven fabric of the present invention has high toughness by optimizing the blending ratio of the organic synthetic fiber A, which exhibits the role of reducing the strength reduction after the initial crack generation, and the organic synthetic fiber B for the purpose of securing the bulk specific gravity. Can be obtained. When the hydraulic material reinforced with fiber is bent and broken, the behavior of the bending strength-deflection curve after the initial crack is generated in the matrix changes depending on the breaking elongation of the fiber. In order to ensure toughness, it is necessary for the fibers to bear stress immediately after the initial cracks are generated in the matrix. In the present invention, the organic synthetic fiber B having a lower elongation at break than the organic synthetic fiber A is used. Since the organic synthetic fiber A, which has a role and has a greater elongation at break than the organic synthetic fiber B with a little delay, further shares the stress, high synergistic effects can ensure high toughness. Here, the tensile strength of the fiber A is preferably 1000 N / mm ² or more, more preferably 1100 N / mm ² or more, while the tensile strength of the fiber B is preferably 800 N / mm ² or more, more preferably 900 N / mm. ² or more.
[0012]
As the fiber used in the present invention, among organic synthetic fibers, polyvinyl alcohol fibers are more desirable in adhesiveness to hydraulic substances such as cement, but the type of fiber is not limited at all, organic synthetic fibers, Any of semi-synthetic fibers, artificial fibers, inorganic fibers, and combinations of two or more thereof may be used. Specific examples include polyester fibers, polyamide fibers, polyolefin fibers, and acrylic fibers.
[0013]
As a method for producing the nonwoven fabric mat of the present invention, for example, the organic synthetic fiber A and the organic synthetic fiber B configured with the weight ratio of the present invention are fed onto a wire net that moves through air-sucking or the like to form a nonwoven fabric. Thereafter, in order to fix the fibers, an adhesive treatment is performed and a drying heat treatment is performed. The adhesive may be sprayed or immersed in an adhesive bath. The bulk specific gravity and thickness can be adjusted by selecting the fineness of the fiber, fiber length, yarn feeding speed, net speed, and press after the adhesive treatment. The adhesive used for fixing the fibers at the time of manufacturing the nonwoven fabric mat has different adhesive properties depending on the type of fiber and the fineness of the single fiber, and therefore, it is preferable to appropriately select from commercially available adhesives. As the adhesive used in the present invention, water-based emulsions such as polyvinyl acetate, melamine ethylene-vinyl acetate copolymer, acrylic and epoxy are preferably used in terms of adhesiveness and workability. Water-soluble polymer adhesives such as polyvinyl alcohol and its modified products can also be used.
[0014]
The high-toughness nonwoven fabric mat of the present invention is a matrix retaining material such as cement for the cement spraying method such as tunnels and slopes, reinforcement of earth and sand such as soil and embankment for civil engineering and cement mortar for on-site construction, It can be used as a crack preventing material and a reinforcing material.
[0015]
【Example】
EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples of the present invention, the polymerization degree, fiber fineness, fiber strength, breaking elongation, and bulk specific gravity of the nonwoven fabric of polyvinyl alcohol mean those measured by the following measuring methods.
[0016]
[Polymerization degree of polyvinyl alcohol]
It measured based on JISK6726.
[0017]
[Fineness dtex]
The weight of a certain sample length of the obtained fibrous material was measured, the apparent fineness was measured at n = 5 or more, and the average value was obtained.
[0018]
[Fiber strength N / mm ² , elongation at break%]
The fiber was left for 24 hours in an atmosphere of temperature 20 ° C and relative humidity 65% in advance, and then the humidity was adjusted to a single fiber length of 10 cm and a tensile speed of 5 cm / min. The fiber strength was measured. The elongation was calculated by single fiber breaking (cm) / gripping length (cm) × 100. When the fiber length was shorter than 10 cm, the maximum length in the possible range of the sample was measured as the gripping length.
[0019]
[Bulk specific gravity of nonwoven fabric g / cm ³ ]
A value obtained by dividing the weight of the nonwoven fabric sheet by the apparent volume occupied by the nonwoven fabric sheet is shown.
[0020]
[Examples 1 to 3, Comparative Examples 1 to 5]
Polyvinyl alcohol having a polymerization degree of 1700 is dissolved in dimethyl sulfoxide (DMSO), a spinning stock solution of 20.7% is solvent-spun and subjected to drawing heat treatment, fiber fineness is 50 dtex, fiber strength is 1000 N / mm ² , elongation at break Two types of fiber A monofilament fibers having 8%, fiber fineness of 100 dtex, fiber strength of 1100 N / mm ² , and elongation at break of 9% were obtained. Further, a spinning stock solution in which polyvinyl alcohol having a polymerization degree of 1700 is made into a 50% aqueous solution is subjected to dry spinning by a conventional method and subjected to a drawing heat treatment, and a fiber fineness of 400 dtex, a fiber strength of 890 N / mm ² , a breaking elongation of 6%, and a fiber fineness of 600 dtex, Two types of fiber B monofilament fibers having a fiber strength of 920 N / mm ² and a breaking elongation of 5% were obtained. The monofilament fibers are each cut to a length of 5 inches, and they are drawn together to form a rope shape, which is then heat treated and defibrated. Furthermore, the fibers A and B that have been disentangled and bulky are mixed in the proportions shown in Table 1, and fed by air blow so as to form a three-dimensional solid gradient on a net having a width of 1.2 m, as an adhesive. After spraying the polyvinyl alcohol resin aqueous solution, the nonwoven fabric was prepared by controlling the thickness to 50 mm and performing dry heat treatment at a temperature of 150 ° C. for 10 minutes. Table 1 shows the structure of the nonwoven fabric mat.
[0021]
[Table 1]

[0022]
The individual nonwoven mats obtained were cut to a width of 10 cm and a length of 40 cm, laid on a steel mold having a width of 10 cm, a length of 40 cm and a height of 5 cm, and a water / cement = 0.35 cement using Portland cement. A test piece was prepared by pouring milk. In casting, a vibration molding machine was used together to maintain uniformity. After placement, the mold was left for 24 hours in a room with a room temperature of 20 ° C. and a humidity of 65%, followed by air curing for 28 days to obtain a fiber reinforced plate. Using the autograph made by Shimadzu Corporation, the specimen after curing was subjected to a bending test with a trisection loading. The measured physical property values are shown in Table 2, and the bending strength-deflection curve is shown in FIG.
[0023]
Since the nonwoven fabric mats of the configurations of Comparative Examples 1 and 2 had a large bulk specific gravity, the cement milk filling property was inferior. In addition, the nonwoven fabric mats of Comparative Examples 3 to 5 had a low bulk specific gravity, so there was no problem in filling with cement milk. However, the fracture strength of the fiber reinforced plate was equal to the initial crack strength or smaller than the fracture strength, and high toughness. It was not obtained.
On the other hand, the fiber reinforced plate using the nonwoven fabric mat having the structure of Examples 1 to 3 is superior to the fiber reinforced plate using the nonwoven fabric mat of Comparative Examples 1 to 5 in terms of filling with cement milk and has an initial breaking strength. Greater toughness was obtained than the crack strength.
[0024]
[Table 2]

[0025]
【The invention's effect】
The hydraulic cured product obtained by using a nonwoven fabric mat having a predetermined bulk specific gravity as a reinforcing material, composed of organic synthetic fiber A and organic synthetic fiber B having different fiber properties, has a decrease in strength immediately after the occurrence of cracks. However, the fracture strength is larger than the initial crack strength, that is, the toughness is high, and the workability is remarkably improved. As a result, a high toughness reinforcing layer with uniform quality can be obtained.
[0026]
[Brief description of the drawings]
FIG. 1 shows bending strength-deflection curves of molded articles obtained in Examples 1 to 3 and Comparative Examples 1 to 5.
[Explanation of symbols]
1: Bending strength of the molded product obtained in Comparative Example 1-Deflection curve 2: Bending strength of the molded product obtained in Comparative Example 2-Deflection curve 3: Bending strength of the molded product obtained in Example 1-Deflection Curve 4: Bending strength of the molded product obtained in Example 2-Deflection curve 5: Bending strength of the molded product obtained in Example 3-Deflection curve 6: Bending strength of the molded product obtained in Comparative Example 3- Deflection curve 7: Bending strength-deflection curve of the moldings obtained in Comparative Example 4 and Comparative Example 5

Claims

It consists of organic synthetic fiber A and organic synthetic fiber B that satisfy the following conditions 1) and 2), and the ratio of organic synthetic fiber A and organic synthetic fiber B is A: B = 80: 20 to 20 : is composed of 80, a bulk specific gravity of a non-woven mat used for repair and reinforcement of the hydraulic substance is 0.008~0.018g / cm ^3, the fracture strength of the hydraulic cured product containing the nonwoven fabric mat A high-toughness nonwoven fabric mat for reinforcing a hydraulic material characterized by being larger than an initial crack strength.
1) The organic synthetic fiber A has a fiber fineness of 80 to 150 dtex and a breaking elongation of 10% or less. , Fracture strength> initial crack strength,
2) The organic synthetic fiber B has a fiber fineness of 300 to 500 dtex and a breaking elongation of 7% or less. , Fracture strength <initial crack strength,

The high-toughness nonwoven fabric mat for reinforcing a hydraulic material according to claim 1, wherein the organic synthetic fiber A and the organic synthetic fiber B are any of polyvinyl alcohol fiber, polyolefin fiber, polyamide fiber, and polyester fiber.