JP2012176854A - Posterior salt damage prevention method of existing reinforced concrete structure - Google Patents
Posterior salt damage prevention method of existing reinforced concrete structure Download PDFInfo
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- Aftertreatments Of Artificial And Natural Stones (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
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Abstract
Description
本発明は鉄筋コンクリート構造物の塩害予防工法に関する。更に詳しくは、塩害予防措置を施していない既設のコンクリート構造物について、事後的に施工可能かつはつり工事不要の塩害予防工法に関する。 The present invention relates to a salt damage prevention method for a reinforced concrete structure. More specifically, the present invention relates to a salt damage prevention method that can be applied afterwards and does not require suspension work for an existing concrete structure that has not been subjected to salt damage prevention measures.
鉄筋コンクリート構造物は現代社会のインフラ設備を構築する上で無くてはならないもの
であるが、鉄筋の腐食いわゆる塩害が課題となっている。
塩害は主に１）川砂や山砂の資源的枯渇による海砂使用による鉄筋コンクリート構造物に同伴される塩化物イオンのほか、２）地下鉄道や地上構造物と接触する地下水に含まれる海水由来の塩化物イオン、海岸より飛来する海塩粒子や凍結防止剤に含まれる塩化ナトリウム由来の塩化物イオンなど、外部環境由来の塩化物イオンにより引き起こされるものがある。以後、上記１）の塩化物イオンについて「内在塩化物イオン」、２）の塩化物イオンについて「外来塩化物イオン」の用語を用いることがある。
Reinforced concrete structures are indispensable for building infrastructure facilities in modern society, but corrosion of the reinforcing bars, so-called salt damage, is a problem.
Salt damage is mainly caused by 1) chloride ions entrained in reinforced concrete structures due to the use of sea sand due to resource depletion of river sand and mountain sand, and 2) derived from seawater contained in underground water in contact with subway and ground structures. Some are caused by chloride ions derived from the external environment, such as chloride ions, sea salt particles flying from the coast, and chloride ions derived from sodium chloride contained in the cryoprotectant. Hereinafter, the term “internal chloride ion” for the chloride ion of 1) and the term “foreign chloride ion” for the chloride ion of 2) may be used.
鉄筋の腐食は、鉄筋位置での塩化物イオン濃度が腐食発生限界塩化物イオン濃度を超
えると、鋼材の不動態被膜が破壊されるため、発生するとされている。従って、鉄筋の腐食を予防するためには、コンクリート躯体内部の塩化物イオン濃度を上記限界塩化物イオン濃度以下にすることが有効と考えられている。腐食発生限界塩化物イオン濃度の値としては１．２ｋｇ／ｍ３の値が提唱されている（コンクリート標準示方書［施工編］、土木学会）。
Corrosion of reinforcing bars is said to occur because the passive film of the steel material is destroyed when the chloride ion concentration at the reinforcing bar position exceeds the corrosion occurrence limit chloride ion concentration. Therefore, in order to prevent corrosion of the reinforcing bars, it is considered effective to make the chloride ion concentration inside the concrete frame below the above limit chloride ion concentration. A value of 1.2 kg / m 3 has been proposed as the value of the corrosion limit chloride ion concentration (Concrete Standard Specification [Construction], Japan Society of Civil Engineers).
塩害を抑制する化合物として、一般式：3CaO・Al2O3・CaX2/m・nH2O［式中、Ｘは１価または２価のアニオンであり、ｍはアニオンの価数を表し、ｎ≦20を表す］で示されるハイドロカルマイトを有効成分とする塩素イオン捕集剤（本発明に言う塩化物イオン吸着剤に相当する。以下「塩化物イオン吸着剤」の用語を用いる。）が開示されている（特許文献１）。上記ハイドロカルマイトにあって、特にXがNO2 −であるハイドロカルマイト（以下「亜硝酸型ハイドロカルマイト」と称する。）を主成分とするものである場合には、当該塩化物イオン吸着剤が鉄筋の腐食要因である塩化物イオンを吸着するのみならず、鉄筋の腐食抑制効果のある亜硝酸イオンを放出する作用を有するため、その所定量をセメント材料に添加することで優れた塩害防止効果を発揮することが知られている(特許文献１)。 As a compound that suppresses salt damage, a general formula: 3CaO · Al 2 O 3 · CaX 2 / m · nH 2 O [wherein X is a monovalent or divalent anion, m represents the valence of the anion, Chloride ion scavenger containing hydrocalumite represented by n ≦ 20] (corresponding to the chloride ion adsorbent according to the present invention. The term “chloride ion adsorbent” is used hereinafter). Is disclosed (Patent Document 1). When the hydrocalumite is mainly composed of hydrocalumite where X is NO 2 — (hereinafter referred to as “nitrite-type hydrocalumite”), the chloride ion adsorption The agent not only adsorbs chloride ions, which are corrosive factors of reinforcing bars, but also releases nitrite ions, which have the effect of inhibiting corrosion of reinforcing bars. It is known to exert a preventive effect (Patent Document 1).
また、塩害により劣化した鉄筋コンクリート構造物について、事後的にその劣化したコンクリート部分を腐食した鉄筋部分が現れるまではつり取り、錆を除去した後の鉄筋表面に塩化物イオン吸着剤を含む防錆ペーストおよび／または防錆モルタルを塗りつけて修復する鉄筋コンクリート構造物の補修方法が提案されている（特許文献２）。 In addition, for reinforced concrete structures that have deteriorated due to salt damage, the rust-proof paste containing chloride ion adsorbent on the surface of the rebar after removing the rust after removing the corroded concrete part after the deterioration A repair method for a reinforced concrete structure that is repaired by applying rust-proof mortar has been proposed (Patent Document 2).
さらに、鉄筋コンクリート構造物を新設するに際して、建設時に予め鉄筋の周囲にセメントと塩化物イオン吸着剤を主成分とする防錆ペーストおよび／または防錆モルタルを施工し、ついで緻密で耐久性の高いモルタルあるいはコンクリートで仕上げる新設のコンクリート構造物の塩害による鉄筋腐食の予防方法が開示されている（特許文献３、特に請求項２）。 Furthermore, when newly constructing a reinforced concrete structure, a rust preventive paste and / or a rust mortar mainly composed of cement and chloride ion adsorbent are pre-installed around the reinforcing bar before construction, and then a dense and highly durable mortar. Or the prevention method of the reinforcement corrosion by the salt damage of the new concrete structure finished with concrete is disclosed (patent document 3, especially claim 2).
他方、既設の鉄筋コンクリート構造物のコンクリート躯体表面に、保護層としてセメント１００重量部に対して塩化物イオン吸着剤を１〜９重量部添加した塩害対策用補修材料にて被覆する鉄筋コンクリート構造物の補修方法（特許文献４、特に請求項１２、実施例６）や、塩分を含んだ雨水等がコンクリート表面から浸透するのを防止するために、コンクリート躯体表面を当該塩害対策用補修材料にて被覆した後、さらに表面処理材をコンクリート表面に被覆する補修方法が開示されている（特許文献４、特に段落[0016]）。 On the other hand, repair of reinforced concrete structures covered with a repair material for salt damage countermeasures in which 1 to 9 parts by weight of chloride ion adsorbent is added to 100 parts by weight of cement as a protective layer on the surface of the concrete frame of existing reinforced concrete structures In order to prevent the method (Patent Document 4, especially Claim 12, Example 6) and rainwater containing salt from permeating from the concrete surface, the surface of the concrete frame was covered with the repair material for countermeasures against salt damage. Thereafter, a repair method for further covering the concrete surface with a surface treatment material is disclosed (Patent Document 4, particularly paragraph [0016]).
特許文献２の補修方法は、既設の鉄筋コンクリート構造物について腐食している鉄筋部分が現れるまではつり取る工事を要する。
特許文献３の方法は、塩化物イオン吸着剤を主成分とする防錆ペーストおよび／または防錆モルタルを鉄筋コンクリート構造物の建設時にその鉄筋の周囲に施工する工程を必須としているため、既設の鉄筋コンクリート構造物に適用することは出来ない。
特許文献４の請求項１２の工法は、新設のコンクリート構造物の躯体表面への塩化物イオン吸着剤を含む補修材料の被覆により、外来塩化物イオンを捕捉することを目的としており、既設のコンクリート構造物であってそのコンクリート躯体表面より内部に向かって塩化物イオンの浸透が既に始まっている鉄筋コンクリート構造物への適用はもとより想定していない。（そのため、上記補修材料中に含まれる塩化物イオン吸着剤の含量は、セメント１００重量部に対し、塩化物イオン吸着剤１〜９重量部の低濃度に抑えられている。）
このように、既設の鉄筋コンクリート構造物であってそのコンクリート躯体表面より内部に向かって塩化物イオンの浸透が既に始まっている鉄筋コンクリート構造物について、
事後的に施工することが可能であり、かつはつり工事が不要の塩害予防工法は未だ知られていない。
The repair method of patent document 2 requires the construction to suspend until the corroded reinforcing bar part appears about the existing reinforced concrete structure.
Since the method of patent document 3 requires the process of constructing the rust prevention paste and / or rust mortar which have a chloride ion adsorbent as a main component around the reinforcement at the time of construction of a reinforced concrete structure, it is the existing reinforced concrete. It cannot be applied to structures.
The construction method of claim 12 of Patent Document 4 is intended to capture foreign chloride ions by covering the surface of a newly-constructed concrete structure with a repair material containing a chloride ion adsorbent. It is not supposed to be applied to a reinforced concrete structure which is a structure and has already been infiltrated with chloride ions from the surface of the concrete frame. (Therefore, the content of chloride ion adsorbent contained in the repair material is suppressed to a low concentration of 1 to 9 parts by weight of chloride ion adsorbent with respect to 100 parts by weight of cement.)
In this way, for existing reinforced concrete structures, the penetration of chloride ions has already started toward the inside from the surface of the concrete frame,
A salt damage prevention method that can be constructed after the fact and does not require a hanger is not yet known.
本発明者らは、鉄筋コンクリート躯体表面に低濃度の塩化物イオン吸着剤を含む層を
一層のみ形成させる上記特許文献４の請求項１２の工法では、外来塩化物イオンが既にコンクリート躯体表面より内部に浸透している既設の鉄筋コンクリート構造物に対して、当該浸透済み外来塩化物イオンを吸着除去する効果が無く、従って、そのような既設の鉄筋コンクリート構造物に対しては塩害を抑止することが出来ないことを確認した。
そこで本発明者等は既設の鉄筋コンクリート構造物の事後的塩害予防工法であって、はつり工事が不要の塩害予防工法について鋭意検討した結果、外来塩化物イオンの浸透が始まっている既設の鉄筋コンクリート構造物であっても、そのコンクリート躯体表面に高濃度の塩化物イオン吸着剤を含有するセメント組成物の水硬化物よりなる層を積層形成することにより、コンクリート躯体表面近傍の塩化物イオン濃度が低減するという効果を発見し、本発明を完成するに至ったものである。
すなわち、本発明は、イ）セメント、細骨材、および当該セメント１００質量部に対し３０〜７０質量部の塩化物イオン吸着剤を含有する組成物を水硬化させてなる塩化物イオン除去層をコンクリート躯体表面に積層形成する工程と、ロ）セメント、細骨材、および当該セメント１００質量部に対し１〜９質量部の塩化物イオン吸着剤を含有する組成物を水硬化させてなる塩化物イオン遮蔽層を前記塩化物イオン除去層に重ねて積層形成する工程と、ハ）前記塩化物イオン遮蔽層の表面に撥水・透湿性の塗膜よりなる表面保護層を形成する工程と を含む既設の鉄筋コンクリート構造物の事後的塩害予防工法である。
In the construction method according to claim 12 of Patent Document 4 in which only one layer containing a low-concentration chloride ion adsorbent is formed on the surface of a reinforced concrete frame, the foreign chloride ions are already present inside the surface of the concrete frame. There is no effect of adsorbing and removing the permeated foreign chloride ions on the existing reinforced concrete structure that has permeated, and therefore, salt damage cannot be prevented for such existing reinforced concrete structure. It was confirmed.
Therefore, the inventors of the present invention are a post-salt salt prevention method for existing reinforced concrete structures, and as a result of intensive investigations on salt damage prevention methods that do not require suspension work, existing reinforced concrete structures that have started to penetrate foreign chloride ions Even so, by forming a layer made of a hardened cement composition containing a high concentration of chloride ion adsorbent on the surface of the concrete body, the chloride ion concentration near the surface of the concrete body is reduced. Thus, the present invention has been completed.
That is, the present invention provides a chloride ion-removing layer obtained by water-curing a composition containing 30 to 70 parts by mass of a chloride ion adsorbent with respect to 100 parts by mass of cement, fine aggregate, and cement. A step of laminating and forming on the surface of the concrete frame; b) chloride obtained by water-curing a composition containing 1 to 9 parts by mass of a chloride ion adsorbent for 100 parts by mass of cement, fine aggregate, and cement And c) forming a surface protective layer made of a water-repellent / moisture permeable coating on the surface of the chloride ion shielding layer. This is a post-salt salt prevention method for existing reinforced concrete structures.
外来塩化物イオンの浸透がコンクリート躯体表面の近傍に留まっている場合には、本発明の塩害予防工法を適用することにより、コンクリート躯体表面近傍の塩化物イオンを効率よく除去することが出来、結果コンクリート躯体表面より内部へ塩化物イオンの浸透が始まっている鉄筋コンクリート構造物の塩害劣化を事後的に抑止することが出来る。 When the penetration of foreign chloride ions remains in the vicinity of the concrete frame surface, the chloride ion near the concrete frame surface can be efficiently removed by applying the salt damage prevention method of the present invention. The salt damage deterioration of reinforced concrete structures where the penetration of chloride ions from the surface of the concrete frame to the inside can be suppressed afterwards.
本発明の第一の形態は、イ）セメント、細骨材、および当該セメント１００質量部に対し３０〜７０質量部の塩化物イオン吸着剤を含有する組成物を水硬化させてなる塩化物イオン除去層をコンクリート躯体表面に積層形成する工程と、ロ）セメント、細骨材、および当該セメント１００質量部に対し１〜９質量部の塩化物イオン吸着剤を含有する組成物を水硬化させてなる塩化物イオン遮蔽層を前記塩化物イオン除去層に重ねて積層形成する工程と、ハ）前記塩化物イオン遮蔽層の表面に撥水・透湿性の塗膜よりなる表面保護層を形成する工程と を含む既設の鉄筋コンクリート構造物の事後的塩害予防工法である。 The first form of the present invention is: a) chloride ion obtained by water-curing a cement, fine aggregate, and a composition containing 30 to 70 parts by mass of a chloride ion adsorbent for 100 parts by mass of the cement. A step of laminating and forming a removal layer on the surface of the concrete frame, and b) hydrosetting a composition containing 1 to 9 parts by mass of a chloride ion adsorbent with respect to 100 parts by mass of cement, fine aggregate, and cement. A step of laminating and forming a chloride ion shielding layer on the chloride ion removal layer; and c) a step of forming a surface protective layer comprising a water-repellent and moisture-permeable coating on the surface of the chloride ion shielding layer. This is a post-salt salt prevention method for existing reinforced concrete structures including and.
本発明の第二の実施形態は、前記第一の実施形態において、塩化物イオン除去層の形成に係るセメント１００質量部に対する塩化物イオン吸着剤の量が５０〜７０質量部である既設の鉄筋コンクリート構造物の事後的塩害予防工法である。 The second embodiment of the present invention is an existing reinforced concrete in which the amount of the chloride ion adsorbent is 50 to 70 parts by mass with respect to 100 parts by mass of cement according to the formation of the chloride ion removal layer in the first embodiment. This is a method for preventing salt damage after construction.
本発明の第三の実施形態は、前記第一または第二のいずれかの実施形態において、前記表面保護層が、前記塩化物イオン遮蔽層の表面に、シラン系またはシラン・シロキサン系の浸透性吸水防止剤を含浸させ、次いで水性アクリルシリコーン系塗料を塗布することにより形成されるものである既設の鉄筋コンクリート構造物の事後的塩害予防工法である。 According to a third embodiment of the present invention, in any one of the first and second embodiments, the surface protective layer has a silane-based or silane-siloxane-based permeability on the surface of the chloride ion shielding layer. This is a post-salt damage prevention method for an existing reinforced concrete structure that is formed by impregnating a water absorption inhibitor and then applying a water-based acrylic silicone paint.
本発明にて用いる前記塩化物イオン吸着剤は、一般式：3CaO・Al2O3・CaX2/m・nH2O［式中、Ｘは１価または２価のアニオンであり、ｍはアニオンの価数を表し、ｎ≦20を表す］で示されるハイドロカルマイトであり、一般式：3CaO・Al2O3・Ca(NO2)2・nH2Oで示される亜硝酸型ハイドロカルマイトが特に好ましい。
ハイドロカルマイトは、例えばアルミン酸ソーダと可溶性カルシウム塩及び／またはアルカリ金属塩と消石灰とからなる原料系を反応・結晶化させる方法（特開平０７−０３３３４０号公報）、CaO・Al2O3系化合物と可溶性カルシウム塩及び／または消石灰とを液中で反応・結晶化させる方法（特開平０７−０３３３４１号公報）により製造することが出来る。
The chloride ion adsorbents used in the present invention have the general formula: 3CaO · Al 2 O 3 · CaX 2 / m · nH 2 O [ wherein, X is a monovalent or divalent anion, m is an anion Is a hydrocalumite represented by the general formula: 3CaO · Al 2 O 3 · Ca (NO 2 ) 2 · nH 2 O Is particularly preferred.
Hydrocalumite is, for example, a method of reacting and crystallizing a raw material system consisting of sodium aluminate and soluble calcium salt and / or alkali metal salt and slaked lime (Japanese Patent Laid-Open No. 07-033340), CaO · Al 2 O 3 type It can be produced by a method of reacting and crystallizing a compound and a soluble calcium salt and / or slaked lime in a liquid (Japanese Patent Laid-Open No. 07-033341).
本発明の塩害予防工法においては、前記したように、鉄筋コンクリート構造物のコンクリート躯体表面に、セメント、細骨材及び高濃度の塩化物イオン吸着剤を含有する塩化物イオン除去層が形成される。塩化物イオン除去層は、以下に述べる塩化物イオン除去機能の他、コンクリート躯体と後述の塩化物イオン遮蔽層との接着層としての役割を果たす。 In the salt damage prevention method of the present invention, as described above, a chloride ion removal layer containing cement, fine aggregate and a high concentration of chloride ion adsorbent is formed on the surface of the concrete frame of the reinforced concrete structure. The chloride ion removal layer plays a role as an adhesive layer between the concrete frame and a chloride ion shielding layer described later, in addition to the chloride ion removal function described below.
当該塩化物イオン除去層は、前記組成物に含まれる塩化物イオン吸着剤のイオン交換作用により、コンクリート躯体表面よりその内部へ外来塩化物イオンの浸透が既に始まっている既設の鉄筋コンクリート構造物中のコンクリート躯体表面近傍の外来塩化物イオンを除去する機能を発揮する。本発明の塩化物イオン除去層の本機能により、塩害予防工法を施していない既設の鉄筋コンクリート構造物であっても、塩化物イオンの浸透がコンクリート躯体表面近傍に限定されており、いまだ鉄筋の腐食が進行していない場合には、本発明の工法を事後的に施すことにより、はつり工事をすることなく、鉄筋コンクリート構造物の塩害を確実に抑止することが可能となる。 The chloride ion removal layer is formed in the existing reinforced concrete structure in which the penetration of foreign chloride ions has already started from the surface of the concrete frame by the ion exchange action of the chloride ion adsorbent contained in the composition. Demonstrates the function of removing foreign chloride ions near the surface of the concrete frame. With this function of the chloride ion removal layer of the present invention, even in an existing reinforced concrete structure that has not been subjected to salt damage prevention, the penetration of chloride ions is limited to the vicinity of the concrete frame surface, and corrosion of the reinforcing bar is still In the case where the process is not proceeding, the salt damage of the reinforced concrete structure can be surely suppressed without performing the lifting work by applying the method of the present invention after the fact.
すなわち、塩化物イオンの浸透が始まっていても、塩化物イオンの浸透がコンクリート躯体表面近傍に留まっている場合には、本発明の塩害予防工法を適用することにより、表面近傍の塩化物イオン濃度を低減することができる。
さらに本発明に用いる塩化物イオン吸着剤は、それ自身が有する陰イオン交換作用により、塩化物イオンを吸着すると同時に亜硝酸イオンを放出するため、塩害抑止の効果を十分に発揮することが出来る。
That is, even if chloride ion penetration has started, if chloride ion penetration remains in the vicinity of the concrete frame surface, the chloride ion concentration near the surface can be obtained by applying the salt damage prevention method of the present invention. Can be reduced.
Furthermore, since the chloride ion adsorbent used in the present invention adsorbs chloride ions and releases nitrite ions at the same time due to its own anion exchange action, it can sufficiently exhibit the effect of inhibiting salt damage.
コンクリート躯体中に埋め込まれている鉄筋部分と直接触れることが無いにも関わらず、塩化物イオン除去層が上記のごときコンクリート躯体表面近傍の外来塩化物イオンを除去する機能は以下の機構により進むものと発明者らは考えている。 The function that the chloride ion removal layer removes extraneous chloride ions near the surface of the concrete frame as described above is advanced by the following mechanism, even though it does not directly touch the reinforcing bars embedded in the concrete frame. The inventors think.
すなわち、塩化物イオン除去層が形成されると、すでに浸透しているコンクリート躯体表面近傍の塩化物イオン濃度と塩化物イオン除去層中の塩化物イオン濃度（当初はゼロである）との間に濃度差が生じる。そうすると拡散により、コンクリート躯体表面近傍の塩化物イオンは上記濃度差が解消するまで塩化物イオン除去層側に移動する。ここで塩化物イオン除去層中には、塩化物イオン吸着剤が存在するので、そのイオン交換作用により塩化物イオン除去層側に移動した塩化物イオンは塩化物イオン吸着剤中に取り込まれ移動が拘束される。この結果塩化物イオン除去層中の拡散移動可能な塩化物イオン濃度が低下するので、引き続きコンクリート躯体表面近傍の塩化物イオンは塩化物イオン除去層側へ移動する。コンクリート躯体表面近傍の塩化物イオンの塩化物イオン除去層側への移動は、塩化物イオン吸着剤による塩化物イオンの吸着作用により、コンクリート躯体表面近傍と塩化物イオン除去層の間の塩化物イオンの濃度勾配が解消するまで継続することとなる。 That is, when the chloride ion removal layer is formed, it is between the chloride ion concentration near the surface of the concrete frame that has already permeated and the chloride ion concentration in the chloride ion removal layer (initially zero). A density difference occurs. Then, due to diffusion, chloride ions near the surface of the concrete frame move to the chloride ion removal layer side until the concentration difference is eliminated. Here, since the chloride ion adsorbent exists in the chloride ion removal layer, the chloride ions moved to the chloride ion removal layer side by the ion exchange action are taken into the chloride ion adsorbent and moved. Be bound. As a result, the concentration of chloride ions that can be diffusely transferred in the chloride ion removal layer decreases, so that chloride ions near the surface of the concrete frame continue to move toward the chloride ion removal layer. The movement of chloride ions near the surface of the concrete frame to the chloride ion removal layer is due to the adsorption of chloride ions by the chloride ion adsorbent, resulting in chloride ions between the surface of the concrete frame and the chloride ion removal layer. This will continue until the concentration gradient is resolved.
従って、当該塩化物イオン除去層に占める塩化物イオンの濃度が高ければ高いほど、塩化物イオン除去層の当該機能の効果が増す。以上の理由により、塩化物イオン除去層の形成に係る組成物中の塩化物イオン吸着剤の含量は高含量であることが好ましい。 Therefore, the higher the concentration of chloride ions in the chloride ion removal layer, the greater the effect of the function of the chloride ion removal layer. For the above reasons, it is preferable that the content of the chloride ion adsorbent in the composition relating to the formation of the chloride ion removal layer is high.
前記塩化物イオン除去層の形成に係るセメント１００質量部に対する塩化物イオン吸着剤の量は、３０〜７０質量部の範囲であることが必要であり、５０〜７０質量部の範囲がより好ましい。塩化物イオンの量が、３０質量部未満である場合は前記した塩化物イオン除去層の機能が十分でなく、７０質量部を超えると塩化物イオン除去層の形成に係る組成物の流動性、塗布の作業性(workability)が損なわれるため実用的でない。当該塩化物イオンの量が、５０〜７０質量部の範囲である場合には塩化物イオン除去機能と塩化物イオン除去層の形成に係る上記組成物の流動性とのバランスが優れる。 The amount of the chloride ion adsorbent with respect to 100 parts by mass of the cement relating to the formation of the chloride ion removal layer needs to be in the range of 30 to 70 parts by mass, and more preferably in the range of 50 to 70 parts by mass. When the amount of chloride ions is less than 30 parts by mass, the function of the above-described chloride ion removal layer is not sufficient, and when it exceeds 70 parts by mass, the fluidity of the composition relating to the formation of the chloride ion removal layer, It is not practical because the workability of the application is impaired. When the amount of the chloride ions is in the range of 50 to 70 parts by mass, the balance between the chloride ion removal function and the fluidity of the composition relating to the formation of the chloride ion removal layer is excellent.
前記塩化物イオン除去層の厚さは２ｍｍ以上４ｍｍ以下の範囲が好ましい。厚さを２ｍｍ未満とすることは施工が困難である上に、塩化物イオン除去層の前記機能の発揮に要する塩化物イオン濃度を高くする必要があり、その結果塩化物イオン除去層の形成に係る前記組成物の流動性が低下し塗布の作業性が悪化するため好ましくない。他方塩化物イオン除去層の厚さが４ｍｍを超えることは、塩化物イオン除去層に構造体として過度の強度的負担を強いることになり、施工上好ましくない。 The thickness of the chloride ion removal layer is preferably in the range of 2 mm to 4 mm. When the thickness is less than 2 mm, it is difficult to construct, and it is necessary to increase the chloride ion concentration required for the function of the chloride ion removing layer to be increased. As a result, the chloride ion removing layer is formed. This is not preferable because the fluidity of the composition is lowered and the workability of the coating is deteriorated. On the other hand, when the thickness of the chloride ion removal layer exceeds 4 mm, an excessive strength burden is imposed on the chloride ion removal layer as a structure, which is not preferable in terms of construction.
本発明においては、前記塩化物イオン除去層に重ねて、セメント、細骨材及び塩化物イオン吸着剤を含有する組成物よりなる公知の塩化物イオン遮蔽層が積層形成される。当該塩化物イオン遮蔽層は外来塩化物イオンを捕捉し、外来塩化物イオンが前記塩化物イオン除去層に到達するのを防ぐ機能を有する。塩化物イオン遮蔽層の当該機能により、前記塩化物イオン除去層中の塩化物イオン吸着剤はもっぱらコンクリート躯体表面近傍の塩化物イオンの除去にのみ消費されることとなるため、本発明の効果がいっそう高まる。 In the present invention, a known chloride ion shielding layer made of a composition containing cement, fine aggregate and a chloride ion adsorbent is laminated on the chloride ion removing layer. The chloride ion shielding layer has a function of capturing foreign chloride ions and preventing the foreign chloride ions from reaching the chloride ion removing layer. Because of the function of the chloride ion shielding layer, the chloride ion adsorbent in the chloride ion removal layer is consumed exclusively for the removal of chloride ions near the surface of the concrete frame. Increases further.
前記塩化物イオン遮蔽層の形成に係るセメント１００質量部に対する塩化物イオン吸着剤の量は、公知の方法に従い、１〜９質量部の範囲に調整される。 The amount of the chloride ion adsorbent with respect to 100 parts by mass of the cement relating to the formation of the chloride ion shielding layer is adjusted in the range of 1 to 9 parts by mass according to a known method.
塩化物イオン遮蔽層の厚さは定法に従い３〜１０ｍｍの範囲であり、より好ましくは３〜５ｍｍの範囲である。塩化物イオン遮蔽層の厚さが３ｍｍ以上の場合には塩化物イオン吸着剤の作用により、前記外来塩化物イオンが効果的に捕捉される。塩化物イオン遮蔽層の厚さが１０ｍｍを超えることは既設コンクリート構造物の寸法を変動させることとなり、好ましくない。 The thickness of the chloride ion shielding layer is in the range of 3 to 10 mm, more preferably in the range of 3 to 5 mm, according to a conventional method. When the thickness of the chloride ion shielding layer is 3 mm or more, the extraneous chloride ions are effectively trapped by the action of the chloride ion adsorbent. When the thickness of the chloride ion shielding layer exceeds 10 mm, the dimensions of the existing concrete structure are changed, which is not preferable.
本発明においては、前記塩化物イオン遮蔽層に重ねて、更に撥水性・透湿性の塗膜よりなる公知の表面保護層が形成される。当該表面保護層の有する撥水性により、海塩粒子や凍結防止剤を含んだ飛沫粒子の付着が抑制されるため、外来塩化物イオンの浸透を一層効果的に抑えることが出来る。また、当該表面保護層の有する透湿性により、鉄筋コンクリート構造体の背面の地中水分や漏水など、コンクリート躯体表面以外より浸入の水分は水蒸気として散逸され、鉄筋の腐食反応の抑制に資する。 In the present invention, a known surface protective layer made of a water-repellent and moisture-permeable coating film is formed on the chloride ion shielding layer. The water repellency of the surface protective layer suppresses the adhesion of sea salt particles or splash particles containing an antifreezing agent, so that the penetration of foreign chloride ions can be more effectively suppressed. In addition, due to the moisture permeability of the surface protective layer, moisture entering from the surface of the concrete frame, such as underground moisture and water leakage on the back of the reinforced concrete structure, is dissipated as water vapor, contributing to the suppression of the corrosion reaction of the reinforcing bars.
前記撥水・透湿性の塗膜よりなる表面保護層は、シラン系またはシラン・シロキサン系の浸透性吸水防止剤（以下「吸水防止剤」と称する）を前記塩化物イオン遮蔽層の表面に塗布して含浸させ、次いで水性アクリルシリコーン系塗料を塗布することによって好適に形成することができる。 The surface protective layer comprising the water repellent / moisture permeable coating is coated with a silane-based or silane-siloxane-based permeable water absorption inhibitor (hereinafter referred to as “water absorption inhibitor”) on the surface of the chloride ion shielding layer. Then, it can be suitably formed by impregnation and then applying a water-based acrylic silicone paint.
上記の吸水防止剤としては、アルキルアルコキシシランを主成分とするシラン系吸水防止剤、ポリオルガノシロキサンを主成分とするシロキサン系吸水防止剤、シラン系とシロキサン系を混合したシラン・シロキサン系吸水防止剤を挙げることが出来る。これらの吸水防止剤については、例えば特開平９−１８９０３０号公報、特公平４−６８２７４号公報、特開２００６−３６５８６号公報に記載されている。
本発明にいう水性アクリルシリコーン系塗料としては、アクリル系樹脂エマルジョンを各種アルコキシシランにてシリコーン変性したものや、シリコーン樹脂をアクリル系モノマーにて乳化グラフト重合変性したものをあげることができる。このような水性アクリルシリコーン系塗料については、例えば特開２０００−１６９７５０号公報、特開２００５−１８７７６５号公報、特開２００６−１０２５８４号公報に記載されている。
The above water absorption inhibitors include silane-based water-absorption inhibitors mainly composed of alkylalkoxysilanes, siloxane-based water-absorption inhibitors mainly composed of polyorganosiloxane, and silane / siloxane-based water absorption inhibitors mixed with silane and siloxane. An agent can be mentioned. These water absorption inhibitors are described in, for example, JP-A-9-189030, JP-B-4-68274, and JP-A-2006-36586.
Examples of the water-based acrylic silicone-based paint according to the present invention include those obtained by modifying an acrylic resin emulsion with various alkoxysilanes and those obtained by subjecting a silicone resin to emulsion graft polymerization modification with an acrylic monomer. Such water-based acrylic silicone-based paints are described in, for example, JP 2000-169750 A, JP 2005-187765 A, and JP 2006-102584 A.
本発明の塩化物イオン除去層または塩化物イオン遮蔽層の形成に係るセメントとしては、ポルトランドセメント、混合セメント、超速硬セメント等を挙げることができるが、これらに限定されるものではなく、コンクリート構造物に使用されているセメントまたは補修工法に適合したセメントを適宜選択して使用することができる。 Examples of the cement relating to the formation of the chloride ion removing layer or the chloride ion shielding layer of the present invention include Portland cement, mixed cement, super-hard cement, etc., but are not limited thereto, and concrete structure The cement used for the object or the cement suitable for the repair method can be appropriately selected and used.
本発明の塩化物イオン除去層または塩化物イオン遮蔽層の形成に係る細骨材としては、一般に市販されている乾燥硅砂、石灰石砕砂などのほか山砂、川砂などを挙げることができる。 Examples of the fine aggregate for forming the chloride ion removing layer or chloride ion shielding layer of the present invention include commercially available dry dredged sand, limestone crushed sand and the like, as well as mountain sand and river sand.
以上のほか、本発明の塩化物イオン除去層および／または塩化物イオン遮蔽層には、上記成分の他セメント系膨張材、繊維、およびポリマー等の混和材料を含ませることもできる。 In addition to the above, the chloride ion removing layer and / or the chloride ion shielding layer of the present invention may contain admixtures such as cement-based expansion materials, fibers, and polymers in addition to the above components.
前記セメント系膨張剤は施工後の収縮を押さえ、被覆表面のひび割れを抑止する。上記のセメント系膨張材としては、アウイン鉱物、酸化カルシウム系化合物が寸法安定性の面から好ましい。 The cement-based expansion agent suppresses shrinkage after construction and suppresses cracks on the coating surface. As the cement-based expansion material, Auin mineral and calcium oxide-based compound are preferable from the viewpoint of dimensional stability.
前記繊維は乾燥収縮によるひび割れを防止する。繊維の種類としては特に限定されるものではないが、ビニロン繊維やプロピレン繊維に代表される高分子繊維類や鋼繊維、ガラス繊維、炭素繊維、ワラストナイト、セピオライトなどの無機繊維類が挙げられる。 The fibers prevent cracking due to drying shrinkage. Although it does not specifically limit as a kind of fiber, Inorganic fibers, such as polymer fiber represented by vinylon fiber and a propylene fiber, steel fiber, glass fiber, carbon fiber, wollastonite, and sepiolite, are mentioned. .
前記ポリマーはコンクリート躯体と塩化物イオン除去層、若しくは塩化物イオン除去層と塩化物イオン遮蔽層との間の付着性を高める効果を奏する。
前記ポリマーとしては、セメント・モルタル用混和材として市販されている公知のポリマーを使用することが出来る。このようなポリマーとして、ゴムラテックスや、ポリアクリル酸エステル重合体、エチレン酢酸ビニル共重合体等の樹脂エマルジョン、その他前記樹脂エマルジョンより得られる再乳化粉末樹脂を挙げることができる。
The polymer has an effect of enhancing adhesion between the concrete frame and the chloride ion removing layer, or between the chloride ion removing layer and the chloride ion shielding layer.
As said polymer, the well-known polymer marketed as an admixture for cement and mortar can be used. Examples of such polymers include rubber latex, resin emulsions such as polyacrylic acid ester polymers and ethylene vinyl acetate copolymers, and other re-emulsified powder resins obtained from the resin emulsions.
本発明において、コンクリート躯体表面に塩化物イオン除去層を形成させるに際してはコンクリート構造物の建築工法の定法に従い、あらかじめコンクリート躯体表面を高圧水などにて洗浄し、適度な湿潤状態を保つことが好ましい。 In the present invention, when the chloride ion removing layer is formed on the surface of the concrete frame, it is preferable to clean the surface of the concrete frame in advance with high-pressure water or the like in accordance with the usual construction method of the concrete structure and maintain an appropriate wet state. .
上記塩化物イオン除去層および塩化物イオン遮蔽層の形成に係る施工方法としては、定法に従い、こて仕上げまたは吹付け仕上げを採用することが出来る。 As a construction method related to the formation of the chloride ion removing layer and the chloride ion shielding layer, a trowel finish or spray finish can be employed according to a conventional method.
以下実施例に基づき、本発明について詳細に説明する。なお、以下の実施例、比較例、参考例において塩化物イオン濃度の測定は、ＪＩＳ
Ａ １１５４（硬貨コンクリート中に含まれる塩化物イオンの試験方法）に拠った。
Hereinafter, based on an Example, this invention is demonstrated in detail. In the following examples, comparative examples, and reference examples, the measurement of chloride ion concentration is JIS
A 1154 (test method for chloride ions contained in coin concrete).
また以下の実施例では、以下の材料を用いた。
１）セメント：普通ポルトランドセメント
２）塩化物イオン吸着剤：亜硝酸型ハイドロカルマイト（日本化学工業株式会社製、商品名：ソルカット）
３）細骨材：市販乾燥硅砂
４）吸水防止剤：シラン系吸水防止剤（イサム塗料株式会社製、商品名「アクアシリカ」）
５）水性アクリルシリコーン塗料：イサム塗料株式会社製、商品名「エコシリカ」
In the following examples, the following materials were used.
1) Cement: Ordinary Portland cement 2) Chloride ion adsorbent: Nitrite-type hydrocalumite (product name: Solkat)
3) Fine aggregate: Commercially available dry cinnabar 4) Water absorption inhibitor: Silane water absorption inhibitor (product name "Aqua Silica" manufactured by Isamu Paint Co., Ltd.)
5) Water-based acrylic silicone paint: Isamu Paint Co., Ltd., trade name “Eco Silica”
［製造例］
＜コンクリート供試体の作成＞
セメント１００質量部、細骨材２００質量部、水６０質量部を混合した組成物を調整し、型枠に流し込み、養生することにより、縦３０ｍｍ、横１００ｍｍ、高さ１５０ｍｍのコンクリート供試体を作成した。
[Production example]
<Creation of concrete specimen>
A concrete specimen having a length of 30 mm, a width of 100 mm, and a height of 150 mm is prepared by adjusting a composition in which 100 parts by mass of cement, 200 parts by mass of fine aggregate, and 60 parts by mass of water are mixed, poured into a mold, and cured. did.
［参考例］
＜塩化物イオン浸透コンクリート供試体の調整＞
上記手順にて得られたコンクリート供試体の六面のうち、縦３０ｍｍ、横１００ｍｍよりなる一面を除く、他の五面をエポキシ樹脂にて封止した。
次いで、このコンクリート供試体を塩化ナトリウム濃度３％の塩水に３箇月間浸漬した。その後、コンクリート供試体を風乾させた。（以下、上記の塩水接触試験を経たコンクリート供試体を「イオン浸透コンクリート供試体」と称し、塩水と直接接触した面を「初期塩水接触面」（Ｓ１）（図２）と称する。
以下の実施例、比較例では当該イオン浸透コンクリート供試体を使用して試験を行った。
なお上記イオン浸透コンクリート供試体の一つについて、上記の初期塩水接触面（Ｓ１）より、深さ１０、２０、３０、５０、１００ｍｍの箇所より各々試験サンプルを採取し塩化物イオン濃度を測定した。結果を参考例として表１第三列目のコラムに示す。
[Reference example]
<Adjustment of chloride ion permeable concrete specimen>
Of the six surfaces of the concrete specimen obtained by the above procedure, the other five surfaces were sealed with epoxy resin except for one surface consisting of 30 mm in length and 100 mm in width.
Next, this concrete specimen was immersed in salt water having a sodium chloride concentration of 3% for 3 months. Thereafter, the concrete specimen was air-dried. (Hereinafter, the concrete specimen subjected to the above-mentioned salt water contact test is referred to as “ion-penetrated concrete specimen”, and the surface directly in contact with salt water is referred to as “initial salt water contact surface” (S 1 ) (FIG. 2).
In the following Examples and Comparative Examples, tests were performed using the ion-penetrated concrete specimens.
In addition, about one of the said ion osmosis concrete specimens, test samples were collected from the above-mentioned initial salt water contact surface (S 1 ) at depths of 10, 20, 30, 50, and 100 mm, and the chloride ion concentration was measured. did. The results are shown in the third column of Table 1 as a reference example.
［実施例１］
＜塩化物イオン除去機能確認試験＞
セメント１００質量部、塩化物イオン吸着剤３０質量部、細骨材１００質量部、水５０質量部を混合した組成物（以下、組成物１と称する。）を調整した。参考例にて調整したイオン浸透コンクリート供試体の初期塩水接触面（Ｓ１）に上記組成物１を塗布することにより、当該組成物１の水硬化物よりなる厚さ３ｍｍの塩化物イオン除去層を積層形成した。
次いで、セメント１００質量部、細骨材２００質量部、塩化物イオン吸着剤５質量部、水５０質量部を混合した組成物（以下、組成物２と称する。）を調整し、上記塩化物イオン除去層の表面に塗布することにより、当該組成物２の水硬化物よりなる厚さ５ｍｍの塩化物イオン遮蔽層を積層形成した。
次いで、上記塩化物イオン遮蔽層の表面に、吸水防止剤を塗布し（塗布量：０．１５ｋｇ／ｍ２）、さらにその上に水性アクリルシリコーン塗料を塗布し（塗布量：０．２０ｋｇ／ｍ２）、表面保護層を形成させた。
かくして得られた塩化物イオン除去層、塩化物イオン遮蔽層および表面保護層を有するコンクリート供試体について、その最外層たる表面保護層の表面を除く他の全ての面をエポキシ樹脂にて封止した。
このようにして調整したコンクリート供試体を塩化ナトリウム濃度３％の塩水に浸漬した。
塩水接触試験開始後、１年および２年経過後のコンクリート供試体につき、図２に示すように、初期塩水接触面（Ｓ１）よりコンクリート供試体内部方向へ１０、２０、３０、５０、１００ｍｍの位置より、各々の試験サンプルを採取し塩化物イオン濃度を測定した。結果を表1に示す。
[Example 1]
<Chloride ion removal function confirmation test>
A composition (hereinafter referred to as composition 1) in which 100 parts by mass of cement, 30 parts by mass of a chloride ion adsorbent, 100 parts by mass of fine aggregate, and 50 parts by mass of water were mixed was prepared. By applying the composition 1 to the initial salt water contact surface (S 1 ) of the ion-penetrated concrete specimen prepared in the reference example, a chloride ion removing layer having a thickness of 3 mm made of a cured product of the composition 1. Were laminated.
Subsequently, a composition in which 100 parts by mass of cement, 200 parts by mass of fine aggregate, 5 parts by mass of a chloride ion adsorbent, and 50 parts by mass of water were mixed (hereinafter referred to as composition 2) was prepared, and the above chloride ions were prepared. By applying on the surface of the removal layer, a chloride ion shielding layer having a thickness of 5 mm made of a cured product of the composition 2 was laminated.
Next, a water absorption inhibitor is applied to the surface of the chloride ion shielding layer (application amount: 0.15 kg / m 2 ), and further an aqueous acrylic silicone paint is applied thereon (application amount: 0.20 kg / m 2 ). 2 ) A surface protective layer was formed.
For the concrete specimen having the chloride ion removing layer, chloride ion shielding layer and surface protective layer thus obtained, all other surfaces except the surface of the outermost surface protective layer were sealed with epoxy resin. .
The concrete specimen prepared in this way was immersed in salt water having a sodium chloride concentration of 3%.
As shown in FIG. 2, the concrete specimens after 1 year and 2 years from the start of the salt water contact test are 10, 20, 30, 50, 100 mm from the initial salt water contact surface (S 1 ) toward the inside of the concrete specimen. From each position, each test sample was collected and the chloride ion concentration was measured. The results are shown in Table 1.
［実施例２］
実施例１において、塩化物イオン除去層の形成に係る塩化物イオン吸着剤の量を５０質量部とした他は同様にして試験を行った。結果を表１に示す。
[Example 2]
A test was conducted in the same manner as in Example 1 except that the amount of the chloride ion adsorbent for forming the chloride ion removal layer was 50 parts by mass. The results are shown in Table 1.
［実施例３］
実施例１において、塩化物イオン除去層の形成に係る塩化物イオン吸着剤の量を７０質量部とした他は同様にして試験を行った。結果を表１に示す。
以上、実施例１〜３より、塩化物イオン除去層の形成に係るセメント１００質量部に対する塩化物イオン吸着剤の量が、３０質量部以上である場合にはコンクリート躯体表面近傍の塩化物イオンの除去機能が優れ、５０質量部以上である場合にはその効果が顕著であることが判る。
[Example 3]
The test was conducted in the same manner as in Example 1 except that the amount of the chloride ion adsorbent for forming the chloride ion removal layer was 70 parts by mass. The results are shown in Table 1.
As described above, from Examples 1 to 3, when the amount of the chloride ion adsorbent with respect to 100 parts by mass of the cement related to the formation of the chloride ion removal layer is 30 parts by mass or more, chloride ions near the surface of the concrete frame It can be seen that when the removal function is excellent and the amount is 50 parts by mass or more, the effect is remarkable.
［比較例１］
実施例１において、塩化物イオン除去層の形成に係る塩化物イオン吸着剤の量を２０質量部とした他は同様にして試験を行った。結果を表１に示す。これより、塩化物イオン除去層中の塩化物イオン濃度が本発明のイ）の要件を満たさない場合には、コンクリート躯体内部に浸透した塩化物イオンを十分に除去することが出来ないことが判る。
[Comparative Example 1]
A test was conducted in the same manner as in Example 1 except that the amount of the chloride ion adsorbent for forming the chloride ion removal layer was 20 parts by mass. The results are shown in Table 1. From this, it can be seen that if the chloride ion concentration in the chloride ion removal layer does not satisfy the requirement of (a) of the present invention, the chloride ions that have penetrated into the concrete frame cannot be removed sufficiently. .
［比較例２］
実施例１において、塩化物イオン除去層の形成に係る塩化物イオン吸着剤の量を８０質量部とした他は同様にして試験を行おうとしたが、組成物１の流動性が著しく低いため、塩化物イオン除去層を形成することが出来なかった。よって以降の試験は中止した。
In Example 1, an attempt was made in the same manner except that the amount of the chloride ion adsorbent for forming the chloride ion removal layer was 80 parts by mass, but the fluidity of the composition 1 was extremely low. A chloride ion removal layer could not be formed. Therefore, the subsequent test was stopped.
１．コンクリート躯体
２．塩化物イオン除去層
３．塩化物イオン遮蔽層
４．表面保護層
５．初期塩水接触面（Ｓ１）
６．塩水接触面（Ｓ２）
７．サンプル採取位置を含む面
1. Concrete frame 2. 2. Chloride ion removal layer 3. Chloride ion shielding layer 4. Surface protective layer Initial salt water contact surface (S 1 )
6). Salt water contact surface (S 2 )
7). Surface including sample collection position
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| JP2019210699A (en) * | 2018-06-05 | 2019-12-12 | 積水化学工業株式会社 | Repair member and repair method for concrete structure |
| JP2020056168A (en) * | 2018-09-28 | 2020-04-09 | 日鉄ケミカル＆マテリアル株式会社 | Reinforcing method for reinforced concrete structure |
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| JP7482484B2 (en) | 2020-09-07 | 2024-05-14 | 独立行政法人国立高等専門学校機構 | Covering structures and covering components for reinforced concrete structures |
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