JP5868739B2 - Ground treatment method after concrete desalination - Google Patents

Description

  The present invention mainly relates to a ground treatment method before applying a surface protective material after desalination treatment by an electrochemical corrosion prevention method, which is performed as a life extension measure for a civil engineering / architectural concrete structure.

  In recent years, as a countermeasure for prolonging the life of salt damage deterioration of concrete structures and improving durability, there is a desalination method of an electrochemical anticorrosion method for the purpose of inhibiting corrosion of reinforcing bars, PC steel and steel in concrete.

  Conventionally, after applying a desalting method, a surface protective material such as an epoxy resin, a urethane resin, or an acrylic resin is applied as a surface protective material in order to prevent re-entry of deterioration factors.

However, after the desalination treatment (application of the desalination method) by the electrochemical anticorrosion method, the concrete is saturated with a high alkaline aqueous solution. Swelling and peeling occur.
Generally, the surface protective material is applied at a stage where the surface moisture content of the concrete is about 5 to 10% or less, but in the desalination treatment, the highly alkaline aqueous solution penetrates into the concrete and does not dry in a short time.

It has been reported that the re-alkalization method in which a highly alkaline aqueous solution penetrates, similar to the desalting method, suppresses the early deterioration and swelling of the surface protective material by using a strong surface protective material for the high alkaline aqueous solution ( Non-patent document 1) The actual condition is that the deformation cannot be completely suppressed, and it is difficult to suppress the occurrence of these problems in the desalination method in which the alkali in the concrete is higher than the realkalization method. .

Annual report of concrete engineering, Vol. 25, no. 1, pp. 1553-1558, 2003

  The present invention provides a ground treatment method that eliminates problems such as alteration, swelling, and peeling of the surface protective material by performing ground treatment measures on the concrete surface after the desalting treatment and before applying the surface protective material.

The present invention provides: (1) After desalting the concrete electrochemical corrosion prevention method, prior to applying the surface coating material, using the poly-cement mortar was mixed with aqueous epoxy resin or polymer as a surface treatment mortar The polymer cement mortar is composed of 200 to 30 parts by mass of an aqueous epoxy resin with respect to 100 parts by mass of cement, and 15 to 0.01 parts by mass of polyacrylate as a polymer with respect to 100 parts by mass of cement. there, substrate treatment method after the concrete desalting, (2) surface treatment method after the concrete desalting of permeability of the lower fabric treatment mortar is not more than ^{1.85 × 10 -11 m / sec (} 1), It is.

  According to the ground treatment method of the present invention, it is possible to eliminate alteration, swelling, peeling, etc. of the surface protective material after the desalting treatment of concrete.

It is sectional drawing of the concrete which apply | coated the polymer cement mortar and surface protection material after a desalination process.

(Explanation of symbols)
1: Surface coating material
2: Surface treatment material (polymer cement mortar)
3: Surface cleansing treatment (blast treatment) before applying the base treatment material
4: Concrete 5: Rebar

Hereinafter, the present invention will be described in detail.
In the present invention, in order to suppress re-entry of the deterioration factor after the desalting treatment, the polymer cement mortar or the mortar in which the aqueous epoxy resin is mixed with the polymer cement mortar is preferably 2 mm or more in applying the surface protective material to the concrete surface. By applying it, the surface protective material is prevented from being prematurely altered, swollen, peeled off, etc., and exhibits surface protective performance. As the surface protective material, generally, an organic epoxy resin or an allyl resin is used.

The base treatment mortar used in the present invention is a polymer cement mortar, and it is preferable to mix an aqueous epoxy resin, an acrylic resin, or a water-based hard urethane resin with the polymer cement mortar, and an aqueous epoxy resin is most preferable.
Polymer cement mortar is a composite material containing cement, sand, polymers, short fibers, admixtures (admixtures), etc., and has adequate adhesion strength and crack resistance. The water permeability of the ground treatment mortar after curing is preferably 1.85 × 10 ⁻¹¹ m / sec or less and high in water tightness.

  The cement used in the present invention is not particularly limited, and various portland cements defined in JIS R 5210, various mixed cements defined in JIS R 5211, JIS R 5212, and JIS R 5213, One or more types selected from blast furnace cement, fly ash cement, filler cement mixed with silica cement, limestone powder, and alumina cement manufactured at the admixture mixing rate specified in JIS or higher can be used. .

In the present invention, an aqueous epoxy resin, an acrylic resin, or a water-based hard urethane resin is mixed with the polymer cement mortar.
Two or more aqueous epoxy resins are contained in one molecule of an epoxy emulsion that can be dispersed in water by addition of a surfactant, or an epoxy-modified acrylic emulsion obtained by emulsion polymerization of a radical polymerizable monomer in the presence of an epoxy resin. An epoxy resin (A) of a compound having an epoxy group and a curing agent (B) for epoxy resin. The epoxy resin (A) is a polyepoxy compound having two or more in one molecule and is not particularly limited as long as it can be dispersed in water, and the epoxy resin curing agent (B) cures the epoxy resin. If it is an effect agent which can do, it will not specifically limit.
The acrylic resin is mainly composed of a derivative of acrylic acid and methacrylic acid. The water-based hard urethane resin has a urethane group NHCOO 3.
The amount of water-based epoxy resin, acrylic resin, or water-based hard urethane resin used is in the range of 200 to 30 parts by mass (in the case of water-based epoxy resin, the total of epoxy resin A and epoxy resin curing agent B) with respect to 100 parts by mass of cement. Is preferred.

The polymer used in the polymer cement mortar of the present invention is not particularly limited, but is usually used for cement admixture, and can be used in either powder or liquid form.
As the polymer type, for example, a cement-mixing polymer (polymer dispersion) specified in JIS A 6203 can be used, and rubber latex such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber. , Ethylene / vinyl acetate copolymer, polyacrylate ester, vinyl acetate vinyl versatate copolymer, and acrylate ester copolymer such as styrene / acrylate copolymer and acrylonitrile / acrylate ester Examples thereof include liquid polymers represented by coalescence and unsaturated polyester resins, and one or more of these can be used.
As for the usage-amount of a polymer, 15-0.01 mass parts is preferable with respect to 100 mass parts of cement.

The short fibers used in the present invention are not particularly limited, but are usually used for cement mixing, and commercially available polymer fibers and inorganic fibers can be used. Examples of fiber types include vinylon fiber, acrylic fiber, nylon fiber, polypropylene fiber, polyethylene fiber, aramid fiber, carbon fiber, glass fiber, cellulose fiber, rock wool, alumina fiber, basalt fiber, and steel fiber. 1 type (s) or 2 or more types selected from can be used.
As for the usage-amount of a short fiber, 3-0.001 mass part is preferable with respect to 100 mass parts of cement.

The admixture (agent) used in the present invention is not particularly limited, and those generally used for cement are used.
For example, the shrinkage-reducing agent suppresses drying shrinkage of mortar, and is not particularly limited, and commercially available ones can be used, and alcohol-based, lower alcohol alkylene oxide derivative-based, glycol-based, A compound having a surfactant activity such as a glycol ether / amino alcohol derivative system or a polyether system can be used. The expansion material is used to reduce curing shrinkage and give chemical prestress, and is not particularly limited. Uses calcium sulfoaluminate-based or lime-based materials and calcium calcium aluminate-based and lime-based composite types. can do.
In addition, fluidizing agents, air entraining agents, rust preventives, thickeners, clay minerals, pozzolanic materials, latent hydraulic materials, quick hardening agents, quick setting agents, antifoaming agents, Various cement admixtures such as antibacterial agents and rosin derivatives can be added.

In the base treatment mortar of the present invention, for example, the blending ratio in the case of consisting of cement, water-based epoxy resin, sand, polymer, and short fiber is not particularly limited, but the water-based epoxy resin is based on 100 parts by weight of cement. 200 to 30 parts by mass, 200 to 10 parts by mass of sand, 15 to 0.01 parts by mass of polymer, and 3 to 0.001 parts by mass of short fibers are preferable.

  Hereinafter, the present invention will be described in more detail based on experimental examples, but the present invention is not limited thereto.

(Experimental example 1)
Concrete specimens (4), in which deformed reinforcing bars (5) are embedded with the composition shown in Table 1, were prepared (Table 1). After curing for 28 days, a desalination method was applied, and blasting was performed after 1 week (3 ), “Without surface treatment mortar” and 4 types of surface treatment mortars, each having a different water permeability from the polymer, were coated with a thickness of 2 mm, and after curing for 1 week, a commercially available epoxy resin-based surface coating material was applied (1 Then, after 12 months, a comparative study of defects such as alteration, floating, and peeling of the epoxy resin surface coating material was conducted (see FIG. 1). The results are shown in Table 2.

(Material used: Concrete)
Cement: Ordinary Portland cement, commercially available fine aggregate: Hokuriku stone cooperative, crushed stone, 5mm lower coarse aggregate: Hokuriku stone cooperative, crushed stone, 20mm sewage: tap water admixture 1: water reducing agent, commercially available NaCl: Industrial and commercial products

(Material used: Ground treatment mortar)
Polymer cement mortar (1): 100 parts by mass of cement, 0.1 part by mass of polymer (polyacrylic acid ester), 0.02 part by mass of short fibers, 200 parts by mass of sand, water permeability 1.20 × 10 ⁻¹⁰ m / sec
Polymer cement mortar (2): 100 parts by mass of cement, 100 parts by mass of aqueous epoxy resin, 0.1 part by mass of polymer (polyacrylate ester), 0.02 parts by mass of short fibers, 40 parts by mass of sand, water permeability 1. 85 × 10 ⁻¹¹ m / sec
-Polymer cement mortar (3): 100 parts by mass of cement, 100 parts by mass of acrylic resin, 0.1 part by mass of polymer (polyacrylic ester), 0.02 parts by mass of short fibers, 40 parts by mass of sand, and water permeability 1.35. × 10 ^-11 m / sec
Polymer cement mortar (4): 100 parts by mass of cement, 100 parts by mass of water-based hard urethane resin, 0.1 part by mass of polymer (polyacrylic acid ester), 0.02 parts by mass of short fibers, 40 parts by mass of sand, water permeability 1 .94 × 10 ⁻¹¹ m / sec
・ Water-based epoxy resin: Commercial product (trade name: Chichibu Epotex, manufactured by Chichibu Concrete Industry Co., Ltd.)
・ Acrylic resin: Commercial product (Brand name Denka Hard Rock, manufactured by Denki Kagaku Kogyo)
・ Water-based hard urethane resin: Commercially available product (Brand name Regimor Hard UW, manufactured by Daido Paint Co., Ltd.)
-Polymer (polyacrylic acid ester): Commercially available product (trade name ELOTX FX4310, manufactured by Akzo Nobel)
・ Cement: Ordinary Portland cement, commercial product ・ Sand: Lime sand, 1.2mm below
・ Short fiber: Commercially available product (Vinylon fiber, length 6 mm, trade name RECS7 × 6, manufactured by Kuraray Co., Ltd.)

(Material used: Surface coating material)
・ Surface coating material (1): Epoxy resin-based, commercially available product (trade name Regigard, manufactured by Dainippon Paint Co., Ltd.)
・ Surface coating material (2): Epoxy resin-based, commercially available product (product name: Lifetex # 2000PC, manufactured by Atomics)
・ Surface coating material (3): Epoxy resin-based, commercially available product (trade name: SRA method, manufactured by Sanyo Resin Co., Ltd.)
・ Surface coating material (4): Acrylic resin-based, commercially available product (Product name: Alonble Coat Z-II, manufactured by Toagosei Co., Ltd.)

(Measuring method)
・ Permeability coefficient of ground treatment mortar: Implemented by output method. The sample was 30 mm thick, and the working pressure was 10 kgf / cm ² .
-Time-dependent change of surface coating material: The specimen was left outdoors, and a portion where deformation (failure) occurred 12 months after construction was visually observed to calculate the area of the deformation portion. Deformation is floating, peeling, or alteration of the surface covering material.

From the results of Table 2, it can be seen that no problems occurred in the four types of commercially available epoxy resin surface coating materials by the ground treatment method of the present invention.

  According to the ground treatment method of the present invention, the surface protective material can be prevented from being altered, swollen, peeled off after the concrete desalting treatment, and thus can be widely used in the civil engineering and construction fields.

Claims (2)

After desalting the concrete electrochemical corrosion prevention method, prior to applying the surface coating material, the polymer cement mortar was mixed with aqueous epoxy resins, polymers made using as the ground processing mortar, polymer cement mortar, aqueous Substrates after concrete desalting treatment , in which an epoxy resin is blended in an amount of 200 to 30 parts by mass with respect to 100 parts by mass of cement and a polyacrylate as a polymer is blended in an amount of 15 to 0.01 parts by mass with respect to 100 parts by mass of cement. Processing method. The ground treatment method after concrete desalting treatment according to claim 1, wherein the water permeability coefficient of the ground treatment mortar is 1.85 × 10 ⁻¹¹ m / sec or less.