JP2006273604A - Rust-preventive agent composition and rust preventive treatment method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rust-preventive agent composition which exhibits excellent conductivity and enables corrosion in a reinforcing steel in an unrepaired part to hardly occur by performing rust-preventive treatment using the composition and which therefore is useful for preventing the occurrence of rust in a steel such as an exposed reinforcing steel when repair mortar is newly placed for connection in the repair construction method for repairing the cross section of a concrete structure, and to provide a rust preventive treatment method using the same. <P>SOLUTION: The the rust-preventive agent composition contains a nitrite and an electroconductive polymer. The rust-preventive agent composition further contains cement. The rust-preventive agent composition further contains a polymer for cement admixing. The rust preventive treatment method uses the rust-preventive agent composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rust preventive composition and a rust preventive treatment method thereof, and particularly a rust preventive agent for preventing rusting of a steel material such as an exposed reinforcing bar when a repair mortar is succeeded in a cross-section repair method for a concrete structure. The present invention relates to a composition and a method for treating rust.

In repair work for concrete structures, cross-section repair work is being carried out to remove the deteriorated part and transfer the repair mortar.
At that time, rust prevention treatment is performed for the purpose of preventing rusting of exposed steel materials such as reinforcing bars.

  Conventional rust inhibitors include nitrites, chromates, silicates, and phosphates in inorganic systems, and organic phosphates, ester salts, organic acids, sulfonic acids, and amines in organic systems. In addition, alkylphenols, mercaptans, nitro compounds, and the like are known (see Non-Patent Document 1).

When performing a cross-section restoration method, a large amount of nitrite rust preventive agent is used, and it is applied directly to the reinforcing bar, mixed with a polymer emulsion, or mixed with a hydraulic substance such as cement. It is used by applying.
When mixed with cement, it is used for cement admixture in order to keep nitrite on the reinforcing bar surface for a long time and to reduce the permeability of chloride ions and oxygen to maintain the rust prevention effect. In some cases, a polymer blend is applied.

  On the other hand, conductive polymers are used in electric and electronic fields such as batteries, capacitors, paints, antistatic materials, organic EL light-emitting materials, electromagnetic wave shields, and printed boards, but are not used in cement concrete. Absent.

"IX Rust preventive", Development technology of concrete admixture, pp119-134, CM Publishing, 2000

Nitrite-based rust preventives often used in cross-section repair methods can be applied directly to the reinforcing bars, but rust may occur if the cross-section is not repaired immediately after application.
In addition, a combination of cement and cement admixture polymer is preferable in that it does not generate rust on the reinforcing bars even if the cross section is not restored immediately after application. If the cross section is repaired with the conductive mortar as it is, the conductivity of the adhered portion is deteriorated and the unrepaired portion is easily corroded.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor uses a rust preventive composition containing a conductive polymer, so that even if it adheres to the underlying concrete, the reinforcing bars of the unrepaired part We have completed a rust-proofing method that prevents corrosion.

  The present invention is a rust inhibitor composition comprising nitrite and a conductive polymer, and further comprising the rust inhibitor composition comprising cement, and further comprising a cement admixture polymer. This rust preventive composition is a rust preventive treatment method using the rust preventive composition.

  The rust preventive composition of the present invention exhibits excellent conductivity, and by using it to carry out a rust prevention treatment, it is possible to make it difficult to cause corrosion of reinforcing bars in unrepaired parts.

Hereinafter, the present invention will be described in detail.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.

  The nitrite used in the present invention is a substance imparting a rust preventive effect, and examples thereof include lithium nitrite, sodium nitrite, potassium nitrite, calcium nitrite, magnesium nitrite, and barium nitrite. Among them, it is preferable to use lithium nitrite or calcium nitrite which does not affect the price and alkali aggregate reaction.

The conductive polymer used in the present invention is a heteroatom-containing conductive polymer such as polypyrroles, polyanilines, polythiophenes, and polythienylene vinylenes, polyacetylenes, polyazulenes, polyphenylenes, polyphenylene vinylenes, polyacene. , Hydrocarbon-based conductive polymers such as polyphenylacetylenes and polydiacetylenes. These conductive polymers can be used in either a powder form or a dispersion in which water is dispersed. Of these, use of polythiophenes exhibiting relatively high conductivity is preferable.
The amount of the conductive polymer used is preferably 0.1 to 20 parts and more preferably 0.5 to 10 parts with respect to 100 parts of nitrite. If it is less than 0.1 part, it may be difficult to impart conductivity to the mortar, and if it exceeds 20 parts, the strength of the mortar may be reduced.

The cement used in the present invention is not particularly limited, but various portland cements defined in JIS R 5210, various mixed cements defined in JIS R 5211, JIS R 5212, and JIS R 5213, In addition, one or two or more types selected from the group consisting of blast furnace cement, fly ash cement, silica cement, limestone powder mixed with blast furnace cement, fly ash cement manufactured at the above admixture ratio specified in JIS may be mentioned.
The amount of cement used is preferably 80 to 400 parts, more preferably 150 to 300 parts, per 100 parts of nitrite. If it is less than 80 parts, the time from application to rusting may be short, and if it exceeds 400 parts, it may be difficult to apply.

The polymer for cement admixture used in the present invention (hereinafter referred to as cement polymer) is defined in JIS A 6203, and is a polymer that has been generally used for cement admixture. It is used for the purpose of improving durability such as salt damage and frost damage. For example, rubber latex such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber, ethylene-vinyl acetate copolymer, polyacrylate copolymer, vinyl acetate vinyl versatate copolymer, styrene -Synthetic resin emulsions such as acrylic acid ester copolymers, and liquid polymers typified by epoxy resins and unsaturated polyester resins can be used, and one or a mixture of two or more of these can also be used.
The amount of the cement polymer used is preferably 2 to 50 parts, more preferably 5 to 30 parts per 100 parts of nitrite. If it is less than 2 parts, the shielding effect of chloride ions and the like may be small when used in combination with cement, and if it exceeds 50 parts, the conductivity may decrease.

In the present invention, it is preferable to use an electron donating agent in combination with the rust preventive composition because the conductivity can be further improved.
Examples of the electron donating agent include chlorine, bromine, iodine, halogens such as these compounds, and Lewis acids such as phosphorus pentafluoride, arsenic pentafluoride, and antimony pentafluoride.

  In the rust preventive composition of the present invention, a pozzolanic substance that is stimulated and hardened by an alkali which is a hydraulic substance other than cement, a calcium aluminate capable of imparting rapid hardening, and a mixture thereof adversely affect conductivity. Can be used in combination as long as they are not given.

  Furthermore, it can also be used as a rust inhibitor composition in which mortar is mixed with sand appropriately.

  In addition, the rust preventive composition of the present invention is within a range that does not adversely affect the quality, carbon black, surfactant, fibers, thickener, clay mineral, setting accelerator, setting retarder, waterproofing agent, and Various additives such as antibacterial agents can be used in combination.

  Although the construction method of the rust preventive composition of the present invention is not particularly limited, for example, it may be sprayed on a reinforcing bar using a sprayer or may be applied with a brush.

Experimental example 1
A rust preventive composition was prepared by blending the conductive polymer shown in Table 2 with 100 parts of the solid content of the nitrous acid aqueous solution, and was cured in air at a temperature of 20 ° C and a humidity of 80%. When applied to a JIS mortar board of 40 mm length × 40 mm width × 10 mm thickness specified by R 5201 with a brush so that the applied amount is approximately 150 g / m ^2, and when it is applied to the resistance value and rebar The time until rusting was confirmed. The results are also shown in Table 1.

<Materials used>
Nitrite aqueous solution: Lithium nitrite aqueous solution, solid content 25%, commercial conductive polymer A: Polyethyleneoxydioxythiophene aqueous dispersion, solid content 1.2%, commercial conductive polymer B: polypyrrole, commercial product

<Measurement method>
Resistivity: Conductivity test, applied to a JIS mortar plate 40mm long x 40mm wide x 10mm thick with a brush so that the applied amount is approximately 150g / m2, and then an aluminum electrode on the coated and non-coated surfaces Is calculated from the equation of resistivity (Ω · cm) = (resistance × electrode area) / distance between electrodes using an impedance measuring device. Time until rusting: D16 rebar with rust inhibitor Apply the composition, leave it in a constant temperature and high humidity chamber at 20 ° C and 100%, and observe the time when rust occurs

Experimental example 2
An antirust agent composition was prepared by blending 250 parts of cement, 100 parts of solid content of aqueous nitrite solution, and 100 parts of solid content of aqueous nitrite solution with the conductive polymer shown in Table 2, and the resistivity and prevention It was confirmed that it was rusting. The results are also shown in Table 2.

<Materials used>
Cement: Ordinary Portland cement, commercial product

<Test method>
Rust prevention: Rust prevention test conducted according to JHS-415

Experimental example 3
A rust inhibitor composition is prepared by blending 0.5 part of the conductive polymer A and the cement shown in Table 3 with respect to 100 parts of the solid content of the aqueous nitrite solution, and the time until rusting, resistivity, and The antirust property was confirmed. The results are also shown in Table 3.

Experimental Example 4
Conductive polymer A0.6 part and cement polymer shown in Table 4 were blended with 250 parts of cement and 100 parts of solid content of the nitrite aqueous solution, and a rust preventive composition was prepared to confirm the resistivity. The results are also shown in Table 4.

<Materials used>
Cement polymer: Ethylene-vinyl acetate emulsion, solid content 45%, commercial product

Experimental Example 5
A rust inhibitor composition is prepared by blending 0.5 parts of conductive polymer A, 250 parts of cement and cement polymer shown in Table 5 with 100 parts of solid content of nitrite aqueous solution, and the penetration depth of chloride ions The resistivity and rust resistance were confirmed. The results are also shown in Table 5.

<Measurement method>
Chloride ion penetration depth: Salt barrier, compliant with JIS A 1171

Claims (4)

  A rust preventive composition comprising nitrite and a conductive polymer.   Furthermore, the rust preventive composition of Claim 1 formed by containing a cement.   Furthermore, the rust preventive composition of Claim 1 or Claim 2 containing the polymer for cement admixture.   The rust prevention processing method using the rust preventive composition of any one of Claims 1-3.