JP2017210815A - Conservation method and coating material for reinforced concrete structure - Google Patents
Conservation method and coating material for reinforced concrete structure Download PDFInfo
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本発明は、コンクリート構造物のコンクリート内部にある鉄筋等の鋼材を腐食から長期間保護する、主に土木・建築分野において予防保全的に、もしくはすでに腐食が開始しているコンクリート内部にある鉄筋等の鋼材の腐食速度を抑制する、鉄筋コンクリート構造物の保全工法に関するものであって、特に、亜硝酸イオンを簡便な手法で効率良く長期間にわたってコンクリート内部に浸透させる鉄筋コンクリート構造物の保全工法に関する。 The present invention protects a steel material such as a reinforcing bar in the concrete of a concrete structure from corrosion for a long period of time, mainly in a civil engineering / architectural field for preventive maintenance, or in a concrete that has already started corrosion. The present invention relates to a maintenance method for a reinforced concrete structure that suppresses the corrosion rate of steel materials, and particularly relates to a maintenance method for a reinforced concrete structure in which nitrite ions are efficiently permeated into the concrete over a long period of time by a simple method.
コンクリート構造物の劣化要因としては、塩害、中性化、凍害、アルカリ骨材反応、及び化学的コンクリート腐食等が挙げられる。劣化が発生した構造物に対する選択可能な補修工法として、断面修復工法、表面保護工法、ひび割れ補修工法、除塩工法，電気防食工法，およびこれらの工法に表面保護工法を併用する工法が知られている。一般にこれらの対策は、コンクリート構造物が劣化した後に実施される対策であり、対策には多くの費用が発生するとともに再劣化のリスクも発生する。そこで、コンクリート構造物の劣化がまだ顕在化する前に予防保全的な対応がとられることがある。その対策の主なものとして、表面保護工法、アルカリ付与工法、表面含浸工法などが知られている。
しかし、表面保護工法は、定期的な表面被覆材の塗り替えが必要なことやピンホール等で想定外の劣化が進行するリスクがあり、アルカリ付与工法はアルカリの浸透性に課題があり、十分な予防保全効果が得られないリスクがあり、表面含浸工法は含浸剤の浸透が所定の深さまで達しないことがあるなど、当初期待した予防保全効果が十分に得られないリスクがあるものであった。
Factors that deteriorate concrete structures include salt damage, neutralization, frost damage, alkali aggregate reaction, and chemical concrete corrosion. Known repair methods for structures that have deteriorated include cross-sectional restoration methods, surface protection methods, crack repair methods, salt removal methods, cathodic protection methods, and methods that combine these methods with surface protection methods. Yes. In general, these measures are implemented after the concrete structure is deteriorated, and the measure involves a lot of costs and a risk of re-deterioration. Therefore, preventive maintenance measures may be taken before the deterioration of the concrete structure is still apparent. As the main countermeasures, a surface protection method, an alkali application method, a surface impregnation method and the like are known.
However, the surface protection method has a risk that it is necessary to periodically repaint the surface coating material and there is a risk of unexpected deterioration due to pinholes, etc. There is a risk that the preventive maintenance effect cannot be obtained, and the surface impregnation method has a risk that the preventive maintenance effect expected initially cannot be obtained sufficiently, such as the penetration of the impregnating agent may not reach the predetermined depth. .
表面含浸工法によって防錆効果のある成分を付与する技術としては、アルキニルオキシ基含有ポリアルキレンオキサイドを含有した亜硝酸塩水溶液を塗布する工法（特許文献１）、シリコーンオイル、選択されたアルコールおよびケイ酸含有水溶液に二酸化ケイ素を溶解させた水溶液を塗布する工法（特許文献２）、水と一種以上の水溶性珪酸塩とコロイド状珪酸塩と還元剤とを含み、水溶性珪酸塩には周期律表第１Ａ族に属するアルカリ金属を含み、還元剤がチオ尿素またはチオ硫酸ナトリウムのいずれかであることを特徴とする改質剤を塗布する工法（特許文献３）、特殊な多孔質無機質材料用無溶剤一液常温硬化型含浸材を塗布する工法（特許文献４）、アルキルアルコキシシラン及び／又はその縮合物及びシクロデキストリンが水中に分散してなる吸水防止材を塗布する工法（特許文献５）、アルカリ金属シリケート水溶液にこれと異なる１種類あるいは複数種類のアルカリ金属イオン源を配合した水溶液に対して、重量比５〜２０％でシランシロキサン系エマルジョンを混合して、１液性としたことを特徴とするケイ酸塩系コンクリート表面撥水含浸材を塗布する工法（特許文献６）や、ケイ酸塩系表面含浸材とコンクリートとの反応を促進する反応促進材であって、当該反応促進材がカルシウム成分と亜硝酸塩とを含有することを特徴とする反応促進材を塗布する工法（特許文献７）などが知られている。
しかし、これらの技術は溶液を塗布してコンクリートへ浸透させるため、低い粘性を特徴とする技術であり、上面からの浸透には有利であるが、壁面や天井面への浸透は思うようにいかない難点があった。
As a technique for imparting a component having an antirust effect by the surface impregnation method, a method of applying a nitrite aqueous solution containing an alkynyloxy group-containing polyalkylene oxide (Patent Document 1), silicone oil, selected alcohol and silicic acid A method of applying an aqueous solution in which silicon dioxide is dissolved in an aqueous solution (Patent Document 2), including water, one or more water-soluble silicates, a colloidal silicate, and a reducing agent. A method of applying a modifier containing an alkali metal belonging to Group 1A, wherein the reducing agent is either thiourea or sodium thiosulfate (Patent Document 3), special porous inorganic material useless Method of applying a solvent one-component room temperature curing type impregnating material (Patent Document 4), alkylalkoxysilane and / or its condensate and cyclodextrin are in water A method of applying a water-absorbing preventing material dispersed (Patent Document 5), an aqueous solution in which one or more alkali metal ion sources different from this are mixed in an aqueous alkali metal silicate solution at a weight ratio of 5 to 20%. A silicate-based concrete surface water-repellent impregnating method characterized by mixing a silanesiloxane-based emulsion into a one-component type (Patent Document 6), a silicate-based surface impregnating material and concrete A method of applying a reaction accelerator (Patent Document 7), which is a reaction accelerator that promotes the reaction, is characterized in that the reaction accelerator contains a calcium component and nitrite.
However, these techniques are characterized by low viscosity because they apply the solution and permeate into the concrete, which is advantageous for permeation from the top surface. There were no difficulties.
同様に亜硝酸リチウム溶液を含浸させた上でポリマーセメント組成物で被覆する工法（特許文献８）、ケイ酸塩の水溶液を含浸させた上で亜硝酸カルシウムの水溶液をさらに含浸させる工法（特許文献９）、セメント系組成体の表面に、珪弗化水素酸金属塩の水溶液を塗布し、乾燥後に、前記セメント系組成体の表面に、浸透性を有する吸水防止材を塗布する工法（特許文献１０）、母材コンクリートに生じたひび割れ部の表面を目止めシールで塞ぎ、浸透性吸水防止材を、ひび割れ部の内部に注入し、ひび割れ部内のコンクリート表面に浸透性吸水防止材を浸透させて吸水防止層を形成したことを特徴とする工法（特許文献１１）なども知られている。
しかし、これらの技術は同じ施工面に対して数回の施工作業が必要であり、作業手間がかかる難点があった。
Similarly, a method of impregnating a lithium nitrite solution and then coating with a polymer cement composition (Patent Document 8), a method of impregnating an aqueous solution of silicate and further impregnating an aqueous solution of calcium nitrite (Patent Document) 9) A method of applying an aqueous solution of a metal hydrofluoride salt to the surface of the cementitious composition, and after drying, applying a water absorption preventing material having permeability to the surface of the cementitious composition (Patent Document) 10) Seal the surface of the cracked part in the base material concrete with a sealing seal, inject the permeable water absorption prevention material into the cracked part, and infiltrate the permeable water absorption prevention material into the concrete surface in the cracked part. A construction method (Patent Document 11) characterized by forming a water absorption preventing layer is also known.
However, these techniques require several times of construction work on the same construction surface, and there is a problem that it takes time and effort.
水溶性リチウム化合物を含む水溶液を吸水させた高吸水性デンプン類を電気化学的脱塩工法の電解質部材とする技術（特許文献１２）も知られている。しかし、そもそも電気回路を必要とするため機材の準備の手間がかかるうえ、施工も数週間から数か月は実施する必要があり、容易な施工性という点では難点もあった。 A technique (Patent Document 12) is also known in which superabsorbent starches obtained by absorbing an aqueous solution containing a water-soluble lithium compound are used as an electrolyte member of an electrochemical desalting method. However, since an electric circuit is required in the first place, it takes time and effort to prepare the equipment, and it is necessary to carry out the construction for several weeks to several months.
本発明者は、前記課題を解決すべく種々検討を重ねた結果、特定の粘度をもつ亜硝酸イオンを含有するゲル状物質を使用し、特定の条件でコンクリート表面に塗布を行うことにより、簡便な施工方法で効率的に防錆成分である亜硝酸イオンを長期間にわたってコンクリート内部に浸透させることが可能となり、信頼性の高い鉄筋コンクリート構造物の保全工法を完成するに到った。
本発明は、特定の粘度を持つ亜硝酸イオン含有のゲル状物質を対象となるコンクリート表面に特定量塗布することにより、簡便な施工方法で効率的に防錆成分である亜硝酸イオンを長期間にわたってコンクリート内部に浸透させることが可能となり、信頼性の高い鉄筋コンクリート構造物の保全工法、ならびに該工法に使用される塗布材を提供することを目的とする。
As a result of various studies to solve the above problems, the present inventor has used a gel-like substance containing nitrite ions having a specific viscosity and applied it to the concrete surface under specific conditions. With a simple construction method, nitrite ions, which are rust-preventive components, can be permeated into the concrete for a long period of time, leading to the completion of a highly reliable maintenance method for reinforced concrete structures.
The present invention applies a specific amount of a nitrite ion-containing gel substance having a specific viscosity to a target concrete surface, thereby efficiently applying nitrite ions, which are rust preventive components, for a long period of time with a simple construction method. An object of the present invention is to provide a highly reliable maintenance method for a reinforced concrete structure and a coating material used for the method.
本発明は、上記課題を解決するために、以下の手段を採用する。
（１）亜硝酸イオンの含有量が５質量％以上の水溶液に増粘剤を混和してなる粘度５０００ｍＰａ・ｓ以上１０００００ｍＰａ・ｓ以下のゲル状物質を、鉄筋コンクリート構造物の表面に１００ｇ／ｍ２以上３０００ｇ／ｍ２以下の塗布量で塗布することを特徴とする鉄筋コンクリート構造物の保全工法。
（２）前記増粘剤が、ポリアクリルアミドとポリエチレングリコールとを含むことを特徴とする、（１）の鉄筋コンクリート構造物の保全工法。
（３）前記増粘剤１００質量部中、ポリアクリルアミドが５０質量部以上９０質量部以下、ポリエチレングリコールが１０質量部以上５０質量部以下であることを特徴とする、（２）の鉄筋コンクリート構造物の保全工法。
（４）前記亜硝酸イオンを含有する水溶液が亜硝酸リチウム水溶液であることを特徴とする、（１）〜（３）のいずれかの鉄筋コンクリート構造物の保全工法。
（５）亜硝酸イオンの含有量が５質量％以上の水溶液に増粘剤を混和してなる、粘度５０００ｍＰａ・ｓ以上１０００００ｍＰａ・ｓ以下のゲル状物質である鉄筋コンクリート構造物用塗布材。
（６）前記増粘剤が、ポリアクリルアミドとポリエチレングリコールとを含むことを特徴とする、（５）の鉄筋コンクリート構造物用塗布材。
（７）前記増粘剤１００質量部中、ポリアクリルアミドが５０質量部以上９０質量部以下、ポリエチレングリコールが１０質量部以上５０質量部以下であることを特徴とする、（６）の鉄筋コンクリート構造物用塗布材。
（８）前記亜硝酸イオンを含有する水溶液が亜硝酸リチウム水溶液であることを特徴とする、（５）〜（７）のいずれかの鉄筋コンクリート構造物用塗布材。
The present invention employs the following means in order to solve the above problems.
(1) A gel-like substance having a viscosity of 5000 mPa · s or more and 100000 mPa · s or less obtained by mixing a thickener in an aqueous solution containing 5% by mass or more of nitrite ions is applied to the surface of the reinforced concrete structure at 100 g / m 2. The maintenance method of the reinforced concrete structure characterized by apply | coating with the application amount of 3000 g / m < 2 > or less.
(2) The maintenance method for a reinforced concrete structure according to (1), wherein the thickener contains polyacrylamide and polyethylene glycol.
(3) The reinforced concrete structure according to (2), wherein polyacrylamide is 50 to 90 parts by mass and polyethylene glycol is 10 to 50 parts by mass in 100 parts by mass of the thickener. Conservation method.
(4) The maintenance method for a reinforced concrete structure according to any one of (1) to (3), wherein the aqueous solution containing nitrite ions is an aqueous lithium nitrite solution.
(5) A coating material for a reinforced concrete structure, which is a gel-like substance having a viscosity of 5000 mPa · s or more and 100000 mPa · s or less, obtained by mixing a thickener with an aqueous solution having a nitrite ion content of 5% by mass or more.
(6) The coating material for reinforced concrete structures according to (5), wherein the thickener contains polyacrylamide and polyethylene glycol.
(7) The reinforced concrete structure according to (6), wherein polyacrylamide is from 50 parts by weight to 90 parts by weight and polyethylene glycol is from 10 parts by weight to 50 parts by weight in 100 parts by weight of the thickener. Coating material.
(8) The coating material for reinforced concrete structures according to any one of (5) to (7), wherein the aqueous solution containing nitrite ions is an aqueous lithium nitrite solution.
本発明により、簡便な施工方法で効率的に防錆成分である亜硝酸イオンを長期間にわたってコンクリート内部に浸透させることが可能となり、信頼性の高い鉄筋コンクリート構造物の保全が出来る。 According to the present invention, it is possible to efficiently infiltrate concrete with nitrite ions, which are rust preventive components, over a long period of time by a simple construction method, and it is possible to maintain a highly reliable reinforced concrete structure.
以下、本発明を詳細に説明する。
なお、本発明における部や％は特に断りがない限り、質量基準で示す。
Hereinafter, the present invention will be described in detail.
In addition, unless otherwise indicated, the part and% in this invention are shown on a mass basis.
本発明で使用する亜硝酸イオンを含有する水溶液は、防錆成分である亜硝酸イオンを含有する水溶液であり、本発明で規定する亜硝酸イオンを含有するものであればよい。一般に金属塩の水溶液として、亜硝酸カリウム、亜硝酸カルシウム、亜硝酸ナトリウム、亜硝酸バリウム、亜硝酸リチウムなどの水溶液が知られている。その他の成分については特に限定するものではなく、硝酸イオン、炭酸イオンなどが混在しても本発明の目的を阻害しない限り問題ない。中でも亜硝酸リチウム水溶液は、コンクリートのアルカリシリカ反応を抑制する効果も付与することができることから、より好ましいものである。 The aqueous solution containing nitrite ions used in the present invention is an aqueous solution containing nitrite ions, which is a rust preventive component, as long as it contains nitrite ions as defined in the present invention. In general, aqueous solutions of potassium nitrite, calcium nitrite, sodium nitrite, barium nitrite, lithium nitrite and the like are known as aqueous solutions of metal salts. Other components are not particularly limited, and even if nitrate ions, carbonate ions, and the like are mixed, there is no problem as long as the object of the present invention is not impaired. Among these, an aqueous lithium nitrite solution is more preferable because it can also impart an effect of suppressing the alkali silica reaction of concrete.
水溶液中に含まれる亜硝酸イオンの量は、５％以上であり、１０％以上４０％以下が好ましく、３５％以上４０％以下がより好ましい。水溶液中に含まれる亜硝酸イオンが５％未満では、鉄筋に十分な量の亜硝酸イオンを供給することができず、本発明の効果が十分に得られない。なお４０％を超えた飽和状態に近いものでも効果はあるが、効果は頭打ちとなるため経済的でない。 The amount of nitrite ions contained in the aqueous solution is 5% or more, preferably 10% or more and 40% or less, and more preferably 35% or more and 40% or less. When the amount of nitrite ions contained in the aqueous solution is less than 5%, a sufficient amount of nitrite ions cannot be supplied to the reinforcing bars, and the effects of the present invention cannot be obtained sufficiently. Even if it is close to a saturation state exceeding 40%, there is an effect, but the effect reaches a peak and is not economical.
本発明で使用する増粘剤は、本発明で規定する粘度が得られるものであれば特に限定されるものではないが、セルロースを主体としたものや、スターチエーテル、グルカン、デュータンガム、グァーガム、スターチエーテル、アルキルアリルスルホン酸とアルキルアンモニウム塩併用系やそれらを合成した合成ポリマー系の増粘剤、ポリアクリル酸ナトリウムを主体とした吸水性高分子などを使用することができる。好ましい増粘剤は、ポリアクリルアミドとポリエチレングリコールとを含むものであり、増粘剤１００部中、ポリアクリルアミドが５０部以上９０部以下、ポリエチレングリコールが１０部以上５０部以下のものが特に好ましい。該増粘剤を用いることで、塗布材が、気中においても鉄筋コンクリート構造物表面に強固に付着した状態で長期的に残存し、亜硝酸イオンをコンクリート中に供給できる効果が得られる。 The thickener used in the present invention is not particularly limited as long as the viscosity specified in the present invention can be obtained, but those mainly composed of cellulose, starch ether, glucan, dutan gum, guar gum, starch Ether, alkylallylsulfonic acid and alkylammonium salt combined systems, synthetic polymer-based thickeners obtained by synthesizing them, water-absorbing polymers mainly composed of sodium polyacrylate, and the like can be used. A preferred thickener includes polyacrylamide and polyethylene glycol, and among 100 parts of the thickener, polyacrylamide is preferably 50 parts or more and 90 parts or less, and polyethylene glycol is preferably 10 parts or more and 50 parts or less. By using the thickener, the coating material remains for a long time in the state of being firmly attached to the surface of the reinforced concrete structure even in the air, and an effect of supplying nitrite ions into the concrete can be obtained.
本発明で使用する亜硝酸イオンと増粘剤を混和したゲル状物質は、粘度５０００ｍＰａ・ｓ以上１０００００ｍＰａ・ｓ以下であり、１００００ｍＰａ・ｓ以上５００００ｍＰａ・ｓが好ましい。前記粘度のゲル状物質であることにより、コンクリート構造物の表面への付着量を任意に調整できる。粘度が５０００ｍＰａ・ｓよりも小さいと、壁面や天井面の施工で流れ落ち、所定量の施工が困難になるとともに、施工後に風雨等の影響で鉄筋コンクリート構造物表面から流失し易くなり、長期間にわたって亜硝酸イオンをコンクリート内部に供給することができず、本発明の効果が十分に得られないことがある。粘度が１０００００ｍＰａ・ｓを超えると粘りが強くなり、施工が難しく、亜硝酸イオンの浸透も阻害することがあり、本発明の効果が十分に得られないことがある。 The gel substance mixed with the nitrite ion and the thickener used in the present invention has a viscosity of 5,000 mPa · s to 100,000 mPa · s, preferably 10,000 mPa · s to 50,000 mPa · s. By using the gel-like substance having the viscosity, the amount of adhesion to the surface of the concrete structure can be arbitrarily adjusted. If the viscosity is less than 5000 mPa · s, it will flow down during the construction of walls and ceilings, making it difficult to carry out a predetermined amount of construction. Nitrate ions cannot be supplied into the concrete, and the effects of the present invention may not be sufficiently obtained. When the viscosity exceeds 100,000 mPa · s, the viscosity becomes strong, the construction is difficult, the penetration of nitrite ions may be inhibited, and the effects of the present invention may not be sufficiently obtained.
本発明で使用する亜硝酸イオンと増粘剤を混和したゲル状物質の塗布量は、前述の好ましい範囲の粘度のもので、鉄筋コンクリート構造物の表面に１００ｇ／ｍ２以上３０００ｇ／ｍ２以下が好ましく、５００ｇ／ｍ２以上１０００ｇ／ｍ２以下がより好ましい。１００ｇ／ｍ２より少ないと、十分な亜硝酸イオンを供給できないことがあり、３０００ｇ／ｍ２を超えると施工が困難になるばかりかコストもかさみ、本発明の効果を十分に得られないことがある。 The coating amount of the gel substance mixed with the nitrite ion and the thickener used in the present invention is the above-mentioned preferable range of viscosity, and the surface of the reinforced concrete structure is 100 g / m 2 or more and 3000 g / m 2 or less. Preferably, 500 g / m 2 or more and 1000 g / m 2 or less is more preferable. When the amount is less than 100 g / m 2 , sufficient nitrite ions may not be supplied. When the amount exceeds 3000 g / m 2 , the construction is difficult and the cost is high, and the effects of the present invention cannot be sufficiently obtained. is there.
本発明で使用する亜硝酸イオンと増粘剤を混和したゲル状物質の製造方法は、均一に混ぜることができる既存のいかなる方法でもよい。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、あらかじめその一部、ある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、プロシェアミキサ、及びナウターミキサ等が挙げられる。 The method for producing a gel material mixed with nitrite ions and a thickener used in the present invention may be any existing method that can be uniformly mixed. 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, a proshear mixer, and a nauter mixer.
本発明で使用する亜硝酸イオンと増粘剤を混和したゲル状物質をコンクリート構造物の表面に塗布する方法は、既存のいかなる方法でもよい。はけ塗り、コテ塗り、ローラー塗りなど人の手で塗布する方法や、リシンガンなどのスプレーガン等を用いて圧縮エアを用いて吹き付けて施工する方法がある。
以下、実施例、比較例を挙げてさらに詳細に内容を説明するが、本発明はこれらに限定されるものではない。
Any existing method may be used as a method of applying a gel substance mixed with nitrite ions and a thickener to the surface of a concrete structure used in the present invention. There are a method of applying by hand such as brush coating, trowel coating, roller coating, and a method of spraying with compressed air using a spray gun such as a ricin gun.
Hereinafter, although an example and a comparative example are given and the contents are explained in detail, the present invention is not limited to these.
「実験例１」
１５０×１５０×１５０ｍｍの立方体の鉄筋コンクリート供試体を作製した。コンクリートは単位セメント量２５０ｋｇ／ｍ３、水セメント比５５％、ｓ／ａ＝４５％、スランプ１０±３ｃｍ、空気量４．０±１．０％のコンクリートとした。コンクリートにはあらかじめ塩化物イオン量が２ｋｇ／ｍ３となるように塩化ナトリウムを混和した。
供試体の作製は２０℃の恒温室で行った。内部には、かぶり３ｃｍで公称直径が１９ｍｍの異型鉄筋Ｄ１９を配置している。供試体は型枠に鉄筋を設置し、コンクリートを打設後、翌日に脱型し、２０℃の恒温室内で材齢２８日まで封緘養生を行った。養生終了後、かぶり側の面を下にした状態で以下に示す塗布材を５００ｇ／ｍ２となるように刷毛で塗布した。塗布材の塗布後、新潟県糸魚川市の屋外に６か月間暴露した。暴露終了後、かぶり側の面から鉄筋を避けるようにコンクリートコアを抜き取り、かぶり側の面から１ｃｍずつ、５ｃｍまでコンクリートをスライスした。スライスしたコンクリートはジョークラッシャーとブラウンクラッシャーを用いて１５０μｍ以下の大きさに粉砕し、コンクリート中の全塩化物イオン量をＪＩＳ Ａ １１５４「硬化コンクリート中に含まれる塩化物イオンの試験方法」により、亜硝酸イオン量をイオンクロマトグラフにより測定した。
測定結果から、各コンクリートスライスのサンプルに含まれる塩化物イオンと亜硝酸イオンのモル比である〔ＮＯ２／Ｃｌ〕比を算出し、鉄筋位置（かぶり面から３〜４ｃｍ）での〔ＮＯ２／Ｃｌ〕比を比較した。また、同時に鉄筋を供試体から取り出し、変色している箇所をマーキングして鉄筋の腐食面積を計測した。結果を表１に示す。
"Experiment 1"
A 150 × 150 × 150 mm cubic reinforced concrete specimen was prepared. The concrete was a concrete having a unit cement amount of 250 kg / m 3 , a water cement ratio of 55%, s / a = 45%, a slump of 10 ± 3 cm, and an air amount of 4.0 ± 1.0%. Sodium chloride was mixed in the concrete in advance so that the chloride ion amount was 2 kg / m 3 .
The specimen was produced in a constant temperature room at 20 ° C. Inside, a deformed reinforcing bar D19 having a cover of 3 cm and a nominal diameter of 19 mm is arranged. The test specimen was provided with reinforcing bars in the formwork, casted with concrete, demolded the next day, and sealed and cured in a constant temperature room at 20 ° C. until the age of 28 days. After curing, the coating material shown below was applied with a brush so that the surface on the cover side was down to 500 g / m 2 . After applying the coating material, it was exposed to the outdoors in Itoigawa City, Niigata Prefecture for 6 months. After the exposure, the concrete core was removed from the cover side surface so as to avoid the reinforcing bars, and the concrete was sliced from the cover side surface to 5 cm in 1 cm increments. The sliced concrete is crushed to a size of 150 μm or less using a jaw crusher and a brown crusher, and the total chloride ion content in the concrete is determined according to JIS A 1154 “Test method for chloride ions contained in hardened concrete”. The amount of nitrate ions was measured by ion chromatography.
From the measurement results, to calculate the molar ratios [NO 2 / Cl] ratio of chloride ion and nitrite ion in the sample of each concrete slice, at rebar position (3-4 cm from head surface) [NO 2 / Cl] ratio was compared. At the same time, the reinforcing bars were taken out from the specimen, and the discolored portions were marked to measure the corrosion area of the reinforcing bars. The results are shown in Table 1.
＜使用材料＞
増粘剤Ａ：増粘剤１００質量部中、市販のポリアクリルアミド粉末７０部、一級試薬のポリエチレングリコール粉末３０部の割合で調整したもの
亜硝酸水溶液Ａ：特級試薬の亜硝酸リチウムを純水に溶解して調整した亜硝酸イオン３５％水溶液
塗布材Ａ：亜硝酸水溶液Ａに増粘剤Ａを混和して粘度２０００ｍＰａ・ｓに調整したもの
塗布材Ｂ：亜硝酸水溶液Ａに増粘剤Ａを混和して粘度５０００ｍＰａ・ｓに調整したもの
塗布材Ｃ：亜硝酸水溶液Ａに増粘剤Ａを混和して粘度１００００ｍＰａ・ｓに調整したもの
塗布材Ｄ：亜硝酸水溶液Ａに増粘剤Ａを混和して粘度３００００ｍＰａ・ｓに調整したもの
塗布材Ｅ：亜硝酸水溶液Ａに増粘剤Ａを混和して粘度５００００ｍＰａ・ｓに調整したもの
塗布材Ｆ：亜硝酸水溶液Ａに増粘剤Ａを混和して粘度１０００００ｍＰａ・ｓに調整したもの
塗布材Ｇ：亜硝酸水溶液Ａに増粘剤Ａを混和して粘度１５００００ｍＰａ・ｓに調整したもの
<Materials used>
Thickener A: 70 parts by weight of a commercially available polyacrylamide powder and 30 parts by weight of a first grade polyethylene glycol powder in 100 parts by weight of a thickener Aqueous nitrous acid A: Lithium nitrite, a special grade reagent, in pure water Dissolved and adjusted nitrite ion 35% aqueous solution coating material A: Thickener A mixed with nitrite aqueous solution A to adjust viscosity to 2000 mPa · s Coating material B: Thickener A added to nitrite aqueous solution A Coating material C mixed and adjusted to a viscosity of 5000 mPa · s Coating material C: Thickener A mixed with a nitrite aqueous solution A and adjusted to a viscosity of 10000 mPa · s Coating material D: Thickener A added to a nitrous acid aqueous solution A Coating material E mixed and adjusted to a viscosity of 30000 mPa · s Coating material E: Thickener A mixed with a nitrous acid aqueous solution A Adjusted to a viscosity of 50000 mPa · s Coating material F: Thickener A added to a nitrous acid aqueous solution A Blend Viscosity 100000 mPa · s as coating material was adjusted to G: those adjusted to a viscosity 150000mPa · s by mixing the thickener A in nitrite solution A
表１より、亜硝酸イオンと増粘剤を混和したゲル状物質の粘度を５０００ｍＰａ・ｓ以上１０００００ｍＰａ・ｓ以下とすることで良好な鉄筋腐食抑制効果を示すことが分かる。
他方、ゲル状物質の粘度が５０００ｍＰａ・ｓ未満である実験Ｎｏ．１−２は、所定量の施工ができず、亜硝酸イオンの供給が十分でないため、鉄筋腐食抑制効果が不十分であった。また、ゲル状物質の粘度が１０００００ｍＰａ・ｓ超である実験Ｎｏ．１−８は、高い粘度が亜硝酸イオンの浸透を阻害し、亜硝酸イオンの供給が十分でないため、鉄筋腐食抑制効果が不十分であった。
From Table 1, it can be seen that a satisfactory reinforcing steel corrosion inhibition effect is exhibited by setting the viscosity of the gel-like substance in which nitrite ions and a thickener are mixed to 5000 mPa · s or more and 100000 mPa · s or less.
On the other hand, in Experiment No. in which the viscosity of the gel-like substance is less than 5000 mPa · s. No. 1-2 was not able to perform a predetermined amount of work, and the supply of nitrite ions was not sufficient, so that the reinforcing bar corrosion suppression effect was insufficient. In addition, Experiment No. in which the viscosity of the gel-like substance is more than 100,000 mPa · s. In No. 1-8, since the high viscosity hinders the penetration of nitrite ions and the supply of nitrite ions is not sufficient, the effect of inhibiting corrosion of reinforcing steel bars was insufficient.
「実験例２」
亜硝酸溶液を種類や濃度を変え、増粘剤Ａを用い、粘度を３００００ｍＰａ・ｓとした塗布材を用いたこと以外は実験例１と同様に試験を行った。結果を表２に示す。
"Experimental example 2"
The test was performed in the same manner as in Experimental Example 1 except that the type and concentration of the nitrous acid solution were changed, the thickener A was used, and the coating material having a viscosity of 30000 mPa · s was used. The results are shown in Table 2.
＜使用材料＞
亜硝酸水溶液Ｂ：１級試薬の亜硝酸カリウムを純水に溶解して調整した亜硝酸イオン３％水溶液
亜硝酸水溶液Ｃ：１級試薬の亜硝酸カリウムを純水に溶解して調整した亜硝酸イオン５％水溶液
亜硝酸水溶液Ｄ：１級試薬の亜硝酸カリウムを純水に溶解して調整した亜硝酸イオン１０％水溶液
亜硝酸水溶液Ｅ：１級試薬の亜硝酸カリウムを純水に溶解して調整した亜硝酸イオン３５％水溶液
亜硝酸水溶液Ｆ：１級試薬の亜硝酸カリウムを純水に溶解して調整した亜硝酸イオン４０％水溶液
亜硝酸水溶液Ｇ：１級試薬の亜硝酸カリウムを純水に溶解して調整した亜硝酸イオン５０％水溶液
亜硝酸水溶液Ａ：１級試薬の亜硝酸リチウムを純水に溶解して調整した亜硝酸イオン３５％水溶液
亜硝酸水溶液Ｈ：１級試薬の亜硝酸ナトリウムを純水に溶解して調整した亜硝酸イオン３５％水溶液
亜硝酸水溶液Ｉ：１級試薬の亜硝酸カルシウムを純水に溶解して調整した亜硝酸イオン３５％水溶液
亜硝酸水溶液Ｊ：１級試薬の亜硝酸バリウムを純水に溶解して調整した亜硝酸イオン３５％水溶液
<Materials used>
Aqueous nitrous acid B: 3% aqueous solution of nitrite ion prepared by dissolving potassium nitrite as a first grade reagent in pure water C: Nitrite ion 5 prepared by dissolving potassium nitrite as a first grade reagent in pure water % Aqueous nitrous acid solution D: prepared by dissolving potassium nitrite of the first grade reagent in pure water 10% aqueous solution of nitrite ion prepared by dissolving the first grade potassium nitrite E: nitrous acid prepared by dissolving the first grade potassium nitrite in pure water Ion 35% aqueous solution Nitrite aqueous solution F: First grade reagent potassium nitrite dissolved in pure water and adjusted 40% aqueous solution Nitrite aqueous solution G: First grade reagent potassium nitrite dissolved in pure water Nitrite ion 50% aqueous solution Nitrous acid aqueous solution A: First grade reagent lithium nitrite dissolved in pure water and adjusted 35% aqueous solution nitrite aqueous solution H: First grade reagent sodium nitrite dissolved in pure water Nitrite ion 35% aqueous solution nitrite aqueous solution I: First grade reagent calcium nitrite dissolved in pure water and adjusted Nitrite ion 35% aqueous solution nitrite aqueous solution J: first grade reagent barium nitrite pure Nitrite ion 35% aqueous solution prepared by dissolving in water
表２より、亜硝酸イオンと増粘剤を混和したゲル状物質に用いる亜硝酸水溶液中に含まれる亜硝酸イオンの量を５％以上とすることで、優れた鉄筋腐食抑制効果を示すことが分かる。より好ましい亜硝酸イオンの含有量は１０％以上４０％以下である。また、亜硝酸水溶液に含まれる金属イオンは、ナトリウム、カリウム、リチウム、バリウムでも同様な鉄筋腐食抑制効果を示すことが分かる。
他方、亜硝酸水溶液中に含まれる亜硝酸イオンの量が５％未満である実験Ｎｏ．２−１では、亜硝酸塩の供給が十分でないため鉄筋腐食抑制効果が不十分であった。
From Table 2, it can be shown that the amount of nitrite ion contained in the nitrite aqueous solution used in the gelled material mixed with nitrite ion and thickener is 5% or more, which shows an excellent corrosion inhibition effect on reinforcing steel bars. I understand. A more preferable content of nitrite ions is 10% or more and 40% or less. Moreover, it turns out that the metal ion contained in nitrous acid aqueous solution shows the same reinforcing bar corrosion inhibitory effect also in sodium, potassium, lithium, and barium.
On the other hand, in Experiment No. 5 in which the amount of nitrite ions contained in the aqueous nitrite solution was less than 5%. In 2-1, since the supply of nitrite was not sufficient, the reinforcing steel corrosion inhibitory effect was insufficient.
「実験例３」
亜硝酸リチウムを用いた亜硝酸イオン濃度３５％の水溶液に増粘剤Ａを用い、粘度を３００００ｍＰａ・ｓとした塗布材Ａを用いて、塗布量を変えたこと以外は実験例１と同様に試験を行った。結果を表３に示す。
"Experiment 3"
Similar to Experimental Example 1 except that the thickener A was used in an aqueous solution of 35% nitrite ion concentration using lithium nitrite and the coating material A was used with a viscosity of 30000 mPa · s, and the coating amount was changed. A test was conducted. The results are shown in Table 3.
表３より、亜硝酸イオンと増粘剤を混和したゲル状物質を鉄筋コンクリート構造物の表面に１００ｇ／ｍ２以上３０００ｇ／ｍ２以下の塗布量とすることで、特に良好な鉄筋腐食抑制効果を示すことが分かる。
なお、ゲル状物質の塗布量が３０００ｇ／ｍ２超である実験Ｎｏ．３−５は、施工の手間がかかる割に鉄筋腐食面積率の低減効果が小さいものであった。
From Table 3, it is possible to obtain a particularly good rebar corrosion inhibition effect by applying a gel-like substance mixed with nitrite ions and a thickener to the surface of the reinforced concrete structure at a coating amount of 100 g / m 2 or more and 3000 g / m 2 or less. You can see that
In addition, experiment No. whose application amount of a gel-like substance is more than 3000 g / m < 2 >. No. 3-5 had a small effect of reducing the corrosion rate of the reinforcing steel bar for the construction work.
「実験例４」
増粘剤を下記に示すように種類を変え、粘度を３００００ｍＰａ・ｓとしたこと以外は実験例１と同様に試験を行った。
また、塗布材塗布後の屋外暴露を１２か月まで継続した際の表面状況を観察した。表面状況観察時の判定基準は以下の通りである。
◎：塗布材の表面に弾力があり、塗布材に水分が残存している。
○：塗布材の表面に弾力はないが、指で表面を触っても壊れない。
△：塗布材の表面に弾力がないが、塗布材は表面に残存している。指で触れるとわずかに壊れる。
結果を表４に示す。
"Experimental example 4"
The test was performed in the same manner as in Experimental Example 1 except that the thickener was changed as shown below and the viscosity was changed to 30000 mPa · s.
Moreover, the surface condition when the outdoor exposure after application | coating material application was continued for 12 months was observed. The criteria for observing the surface condition are as follows.
A: The surface of the coating material is elastic, and moisture remains in the coating material.
○: Although there is no elasticity on the surface of the coating material, it is not broken even if the surface is touched with a finger.
Δ: There is no elasticity on the surface of the coating material, but the coating material remains on the surface. Slightly broken when touched with a finger.
The results are shown in Table 4.
＜使用材料＞
増粘剤Ｂ：メチルセルロース系増粘剤 ハイメトローズ３００００ＰＥ（信越化学社製）
増粘剤Ｃ：スターチエーテル系増粘剤 スタービスＳＥ２５Ｆ（ＢＡＳＦ社製）
増粘剤Ｄ：デュータンガム系増粘剤 （シーピーケルコ社製）
増粘剤Ｅ：グァーガム系増粘剤 （シーピーケルコ社製）
増粘剤Ｆ：アルキルスルホン酸系増粘剤 ビスコトップ（花王製）
増粘剤Ｇ：変性ポリアクリル系吸水性高分子 アクアリックＣＳ （日本触媒製）
増粘剤Ｈ：増粘剤１００質量部中、市販のポリアクリルアミド粉末４５部、一級試薬のポリエチレングリコール粉末５５部の割合で調整したもの
増粘剤Ｉ：増粘剤１００質量部中、市販のポリアクリルアミド粉末５０部、一級試薬のポリエチレングリコール粉末５０部の割合で調整したもの
増粘剤Ｊ：増粘剤１００質量部中、市販のポリアクリルアミド粉末９０部、一級試薬のポリエチレングリコール粉末１０部の割合で調整したもの
増粘剤Ｋ：増粘剤１００質量部中、市販のポリアクリルアミド粉末９５部、一級試薬のポリエチレングリコール粉末５部の割合で調整したもの
<Materials used>
Thickener B: Methylcellulose thickener Himetrozu 30000PE (Shin-Etsu Chemical Co., Ltd.)
Thickener C: Starch ether thickener Starvis SE25F (BASF)
Thickener D: Dutan gum thickener (manufactured by CPE Kelco)
Thickener E: Guar gum thickener (Cheap Kelco)
Thickener F: Alkylsulfonic acid thickener Visco Top (manufactured by Kao)
Thickener G: Modified polyacrylic water-absorbing polymer Aquaric CS (Nippon Shokubai)
Thickener H: Thickener adjusted at a ratio of 45 parts of commercially available polyacrylamide powder and 55 parts of polyethylene glycol powder of primary reagent in 100 parts by weight of thickener Thickener I: Commercially available in 100 parts by weight of thickener Thickener J: 50 parts of polyacrylamide powder and 50 parts of polyethylene glycol powder as primary reagent Thickener J: 90 parts of commercially available polyacrylamide powder and 10 parts of polyethylene glycol powder as primary reagent in 100 parts by weight of thickener Thickener K: Adjusted at a ratio of 95 parts of commercially available polyacrylamide powder and 5 parts of polyethylene glycol powder as a first grade reagent in 100 parts by weight of thickener
表４より、亜硝酸イオンと増粘剤を混和したゲル状物質に使用する増粘剤は、本発明で規定する粘度が得られるものであれば特に限定されるものではなく、各種の増粘剤の使用で、塗布材が、気中においても鉄筋コンクリート構造物表面に長期的に残存し、所定の鉄筋腐食抑制効果が得られる。なかでも、ポリアクリルアミドとポリエチレングリコールとを含む増粘剤は、鉄筋コンクリート構造物表面に塗布材が強固に付着し、特に増粘剤１００部中、ポリアクリルアミドが５０部以上９０部以下、ポリエチレングリコールが１０部以上５０部以下の増粘剤では、塗布材が水分を含み弾力を保った状態で残存し、亜硝酸イオンをコンクリート中に供給できる効果が高いことが分かる。 From Table 4, the thickener used for the gel material mixed with nitrite ion and the thickener is not particularly limited as long as the viscosity specified in the present invention can be obtained. By using the agent, the coating material remains on the surface of the reinforced concrete structure for a long time even in the air, and a predetermined reinforcing steel corrosion inhibiting effect can be obtained. Among them, the thickener containing polyacrylamide and polyethylene glycol has a coating material firmly attached to the surface of the reinforced concrete structure. Especially, in 100 parts of the thickener, polyacrylamide is 50 parts or more and 90 parts or less, polyethylene glycol is It can be seen that the thickener of 10 parts or more and 50 parts or less remains high in a state where the coating material contains moisture and maintains elasticity, and is highly effective in supplying nitrite ions into the concrete.
「実験例５」
実験例１の実験Ｎｏ．１−１とＮｏ．１−５において、コンクリートを打設後、翌日に脱型し、２０℃の恒温室内で材齢２８日まで封緘養生を行ったのち、温度２０℃、湿度６０％、二酸化炭素濃度５％の促進中性化環境条件下に２６週間静置することで養生完了とした以外は、実験例１と同じ条件で試験を実施した。
実験例１の測定項目に加えて、塗布材を塗布したコンクリート面の中性化深さをＪＩＳ Ａ １１５３「コンクリートの促進中性化試験方法」に準拠して測定した。結果を表５に示す。
“Experimental Example 5”
Experiment No. 1 of Experimental Example 1 1-1 and No.1. In 1-5, after casting the concrete, it is demolded the next day and sealed and cured until the age of 28 days in a constant temperature room at 20 ° C., and then promotes temperature 20 ° C., humidity 60%, carbon dioxide concentration 5%. The test was carried out under the same conditions as in Experimental Example 1 except that the curing was completed by leaving it to stand for 26 weeks under neutralized environmental conditions.
In addition to the measurement items of Experimental Example 1, the neutralization depth of the concrete surface to which the coating material was applied was measured in accordance with JIS A 1153 “Promoted Neutralization Test Method for Concrete”. The results are shown in Table 5.
表５より、亜硝酸イオンと増粘剤を混和したゲル状物質は塩害による鉄筋腐食の抑制効果と中性化抑制効果も併せもつことが分かる。 From Table 5, it can be seen that a gel-like substance in which nitrite ions and a thickener are mixed has both an effect of inhibiting rebar corrosion due to salt damage and an effect of inhibiting neutralization.
本発明を使用することにより、塩害を受ける鉄筋コンクリート構造物や中性化の進行した鉄筋コンクリート構造物の外観を損ねることなく、効果的に防錆成分である亜硝酸イオンをコンクリート中に供給することができる。塩害を受けると想定される鉄筋コンクリート構造物や中性化の進行した鉄筋コンクリート構造物の保全工法として広範な用途に適する。
By using the present invention, it is possible to effectively supply nitrite ions, which are rust preventive components, into the concrete without impairing the appearance of the reinforced concrete structure subjected to salt damage or the reinforced concrete structure that has been neutralized. it can. It is suitable for a wide range of applications as a maintenance method for reinforced concrete structures that are expected to be damaged by salt and reinforced concrete structures that have become neutralized.
Claims (8)
The coating material for reinforced concrete structures according to any one of claims 5 to 7, wherein the aqueous solution containing nitrite ions is an aqueous lithium nitrite solution.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019246180A1 (en) | 2018-06-21 | 2019-12-26 | 3M Innovative Properties Company | Mat material, method of making same, pollution control apparatus and thermal insulation |
| WO2020044228A1 (en) | 2018-08-30 | 2020-03-05 | 3M Innovative Properties Company | Holding material and method of manufacturing same, and pollution control apparatus |
| WO2020110026A1 (en) | 2018-11-30 | 2020-06-04 | 3M Innovative Properties Company | Mat material, method of manufacturing same, inorganic adhesive sheet, pollution control device, and thermal insulation |
| WO2021124057A1 (en) | 2019-12-17 | 2021-06-24 | 3M Innovative Properties Company | Thermal insulation structure and method of making same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019246180A1 (en) | 2018-06-21 | 2019-12-26 | 3M Innovative Properties Company | Mat material, method of making same, pollution control apparatus and thermal insulation |
| WO2020044228A1 (en) | 2018-08-30 | 2020-03-05 | 3M Innovative Properties Company | Holding material and method of manufacturing same, and pollution control apparatus |
| WO2020110026A1 (en) | 2018-11-30 | 2020-06-04 | 3M Innovative Properties Company | Mat material, method of manufacturing same, inorganic adhesive sheet, pollution control device, and thermal insulation |
| WO2021124057A1 (en) | 2019-12-17 | 2021-06-24 | 3M Innovative Properties Company | Thermal insulation structure and method of making same |
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