JPS607972A - Rust preventing method of reinforcing steel bar for lightweight foamed concrete - Google Patents

Abstract

PURPOSE:To obtain a rust-proofed reinforcing steel bar by coating the 1st layer coated with a water paint consisting of a high polymer latex contg. an inorg. filler on said bar and coating a cement layer contg. a high polymer latex as the 2nd layer thereon. CONSTITUTION:A high polymer latex contg. an inorg. filler is first coated on a reinforcing steel bar and is dried to stick a film having 10-500mu film thickness to the steel bar. Cement contg. a high polymer latex or mortar contg. a high polymer is coated on the outside circumference thereof and is dried to form a film having 50-2,500mu film thickness thereby forming the paint coated film to a total thickness of 60-3,000mu. Thereby, adhesion to the reinforcing steel bar is improved and the sure effect of preventing rust is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rust prevention method for reinforcing reinforcing bars for lightweight aerated concrete, and in particular, a method for preventing rust of reinforcing reinforcing bars for lightweight cellular concrete, and in particular, a first ruptured film on the reinforcing bars and a second coating that covers the first coating and reinforces the reinforcing bars. This relates to a rust prevention method in which the rust is formed.

Light aerated concrete is made by grinding and mixing calcareous raw materials such as cement and lime with silicic raw materials such as silica sand and silica stone, adding an appropriate amount of water to form a slurry, and adding metal powder such as aluminum to this slurry and stirring. This is then poured into a formwork fitted with reinforcing reinforcing bars, allowed to foam, condense and harden, and then cured in high-temperature, high-pressure steam in an autoclave.

This lightweight cellular concrete has a wide range of uses as an excellent building material, but because it has a large porosity of around 70%,
It has the disadvantage that the reinforcing steel inside it is easily corroded when various gases and liquids penetrate into it. In order to compensate for this, rust-proofing treatment of reinforcing reinforcing bars with a cement-based or polymer-based coating has been carried out for some time. However, several problems have been pointed out with this rust prevention treatment. For example, the cement-based rust preventive agent that is widely used today is a mixture of polymer latex and cement, but when applied to all reinforcing bars, it did not adhere well to the reinforcing bars. In addition, to ensure reliable rust prevention with this rust preventive agent, it is necessary to
It was necessary to form a relatively thick film with J♀, but when applied to reinforcing bars that are easily deformed, such as wire mesh, the foaming resistance of the slurry increases when forming aerated concrete, making it difficult to set the reinforcing bars with precision. This resulted in a decrease in Furthermore, the above-mentioned cement-based rust preventive agents have the disadvantage that the cement in the coating layer is neutralized during long-term use of aerated concrete, resulting in a decrease in rust preventive power. on the other hand,
Polymer-based rust preventive agents are expensive, and there are problems in the adhesion between the rust preventive coating and the concrete matrix.

The inventors have made various efforts to improve the above-mentioned conventional problems. The present invention was completed based on the discovery that by covering the reinforcing steel as a second layer with a cement layer mixed with polymer latex, a reinforcing reinforcing bar that has good adhesion to the reinforcing bars and is reliable for rust-proof moving beds can be obtained.

That is, in this invention, a polymer latex containing an inorganic filler is applied and dried to form a film with a thickness of 10 to 500 μm in close contact with the reinforcing steel, and around the outer periphery of the coating, one mole of polymer latex-containing cement is placed in the polymer latex-containing mortar. was coated and dried to form a film with a thickness of 5o to 2500μ, with a total coating thickness of 6.
This is a rust prevention method for reinforcing reinforcing bars for a'f aerated concrete, characterized in that the reinforcing bars are formed to have a thickness of 0 to 3,000μ.

This invention will be further explained below.

In the present invention, the paint that is applied onto the reinforcing bars to form the first layer is a water-based anti-corrosion paint that mainly contains an inorganic filler and a polymer latex, and optionally contains auxiliary materials added to the outside. Non-mA fE-filled m1 has rust prevention properties and significantly inhibits the water use reaction of cement, and there is no particular limitation on what it is, but examples include lead tetrachloride, white lead, zinc oxide, and Lead, barium metaborate, aluminum phosphate, zinc phosphate, calcium molybdate, calcium borosilicate, aluminum tripolyphosphate, calcium hydroxide,
Zinc chromate, red iron oxide, etc. can be used alone or in combination.

These inorganic fillers have anti-rust properties, and by mixing and applying the polymer latex described below, the corrosion resistance of the reinforcing bars can be further improved.

Further, the polymer latex must have excellent alkali resistance and heat resistance, but its use is not limited to ships. Examples include acrylic resin emulsion, styrene-acrylic copolymer resin emulsion, enalene-beer acetate co-M copolymer resin emulsion, ethylene-vinyl acetate-vinyl chloride copolymer resin emulsion, vinyl acetate rube opa copolymer resin emulsion, and epoxy resin. Resin emulsion such as emulsion and S
Synthetic rubber latex such as DR latex, NBR latex, CR latex, etc. can be used. This resin emulsion or rubber latex is preferably used with a rubber content or an Fi resin content of 5 to 30%. If it is less than 5%, there will be holes in the dried and hardened coating, and the adhesion to the reinforcing bars will be low, while if it exceeds 30%, the mechanical strength will be low and the cost will be high. It is not suitable as it will be low.

The mixing ratio of the above inorganic filler and polymer Radex is:
It is difficult to set the range 1 in which the weight percentage of the inorganic filler in the dry coating film is 2 to 80% to be 1.

This improves the anti-corrosion ability, heat resistance, and adhesion to reinforcing bars. Incidentally, the finer the powder particles of the inorganic filler, the thinner the coating can be and the more the purpose can be achieved. In addition to this, it is also possible to add an auxiliary side depending on the core thickness to improve the strength of the coating film, improve paintability, and reduce costs. Effective materials for this scale include calcium carbonate, Merck, clay, silica powder, agarite, mica, asbestos, diatomaceous earth, and the like. Further, dispersants, thickeners, antifoaming agents, and corrosion inhibitors may also be used as appropriate.

The above-mentioned mixture is uniformly kneaded to obtain water-based anticorrosive paint 1 for the first layer. At this time, the coating method and target film thickness are carefully selected, and the viscosity is adjusted so that a uniform coating film is formed on the reinforcing reinforcing bars when the coating is applied. Application may be by sugley, dipping, or any other suitable method, but the dipping method is suitable in terms of forming a uniform film. The coating film thickness is 10 in dry condition.
A range of ~500μ is preferred. If it is thinner than 10 μm, the desired rust-preventing effect cannot be obtained, and if it exceeds 500 μm, it is economically disadvantageous, and the rust-preventing ability is undesirably reduced due to shifting and cracking of the coating film during drying. In addition,
Coating may be performed multiple times, but it is economical to perform coating as few times as possible. It is not good for the eaves to dry out quickly after application. It is best to set the drying conditions according to the line speed to the extent that this does not occur due to the boiling of the paint or the pulling of the paint film. After the first coating is densely formed on the reinforcing bars as described above, cement containing polymer latex or mortar containing polymer latex is applied thereon and dried.

The polymer latex-containing cement used here contains 2 to 50% by weight of rubber latex or resin emulsion as a rubber or resin content based on cement and cement, and contains other adjuvants such as setting retarders as necessary. .

The mortar mixed with polymeric latex is 300% more filling with relatively coarse silica sand and other materials than cement.
If added within t'l, the adhesion properties can be further improved.

ζ] Fat emulsion is 2% as rubber neck or resin content.
If it is unnamed-1, the corrosion resistance of the reinforcing bar with holes formed in the dry and hardened coating cannot be ensured. However, if the resin content of rubber fC exceeds 50%, the blending ratio of the cement or mortar on the other side of the blend will be poor, resulting in poor adhesion with the concrete matrix.

As the cement, portland cement, fryer cement, blast furnace cement, etc. are used. My neck was
Polymer latex includes SDR, NBR latex,
Synthetic latex such as cR latex and acrylic σ
JJJit emulsion, styrene-acrylic copolymer 41'tj fat emulsion, ethylene-vinyl acetate copolymer resin emulsion, ethylene-vinyl acetate-cyclized vinyl comonomer resin emulsion, vinyl acetate opaque copolymer emulsion)! A resin emulsion with excellent 4-alkalinity such as In is suitable. In order to adjust the pot life of polymer latex and cement to make it suitable for coating, a cement water use reaction retarder can be used. For example, sodium boroheptonate, gluconate, borotartrate, etc. are effective for this purpose.

Coating with polymer latex-containing cement or polymer latex-containing mortar can be done in the same way as coating the first layer with anti-corrosion paint, and the dipping method is suitable if the coating is uniform at 10 points. ing.

The coating range of polymer latex mixed cement is preferably in the range of 5(2) to 2,500 microns in terms of dry film thickness. 50μ is the lower limit film thickness of the moving table using polymer latex mixed cement, 2500μ is the upper limit value when using polymer latex mixed mortar, and the upper limit film thickness when using polymer latex mixed cement. is approximately 500μ, and when using mortar mixed with polymer latex, the thickness of the lower F film is preferably approximately 300μ. The second layer coating is 50μ
If it is too thin, the reinforcing effect of the first layer coating will be small, and 2.
If it exceeds 500μ, the curing time due to drying of the coating film will be long and there is a risk of sagging during drying, which is not preferable. The drying conditions for the coating film are selected depending on the line speed, but in order to ensure the pot life, it is desirable to dry by heating when using a water utilization reaction retarder.

The total thickness of the coating film formed by the rust prevention method of the present invention is in the range of 60 to 3000 μm after drying.

60μ even if fine particles are used as the coating material.
If it is less than 3000, sufficient rust prevention effect cannot be obtained;
If it exceeds &fS, the foaming resistance of the slurry during molding of aerated concrete will increase, which is undesirable.

As described above, according to the present invention, the rust preventive coating is formed from the water-based rust preventive paint forming the first layer and the scraps of polymer latex-containing cement (or mortar) forming the second layer. Compared to conventional methods of preventing caking using cement-based rust preventive materials and anti-corrosion methods using polymeric material-based rust preventive materials, which have been practiced in the industry, several effects can be achieved. First, according to the present invention, the rust-preventive power lasts for a long period of time. This is because a cement layer mixed with FFI 2 polymer latex is formed on top of the first layer of water-based anti-corrosion paint, so the second layer corrects all the defects in the coating film that occur in the first layer. be. Therefore, by using a plurality of layers including the first JP': The second effect of the present invention is that it can be moved by one person, and the force is strong. This is the 11th. 'l-: A polymer latex containing a non-leakage filler was applied to the reinforcing bars, and on top of this, a polymer latex-mixed cement (lx) with good sealability with the concrete matrix was applied. It's C.

Lightweight aerated concrete that uses reinforcing reinforcing bars that form "real holes" has good adhesion to the VC bars, so defects such as cracks will not occur in the coating layer even if the concrete is bent, impacted, or deformed during mortaring. . Further, according to the present invention, a rust-preventing coating layer can be formed because the coating has good adhesion and a good anti-caking effect.

As a result of this effect, the slurry foaming resistance of the reinforcing reinforcing bars is reduced, the deformation of the reinforcing bars is prevented, and the positioning accuracy is improved.

Examples Styrene-acrylic copolymer resin emulsion (solid content 56%) 90 parts (all parts below are heavy duty parts), 20 parts barium metaborate, 20 red red iron, 85 parts calcium carbonate, 75 parts silica sand, 15 parts water, water 60 parts, dispersant Tamorure 31 (trade name of Daiichi Kogyo Seiyaku Co., Ltd.), thickener HEC (hydroxyethyl cellulose) manufactured by Daicel Chemical Industries (a)
0.4 parts, antifoaming agent Nopco 8034 (Nihon Sannoguco (
A water-based anticorrosive paint-1 consisting of 02 parts (trade name) was prepared. The reinforcing steel for cellular concrete was completely immersed in this paint to coat it, and then dried at 80° C. for 10 minutes. The resulting coating film had an average thickness of 150μ.

Next, 100 parts of ordinary Portland cement, 10 parts of acrylic resin emulsion (solid content 50%), 2.2 parts of milk casein, and 0.0 parts of indium borohezotonate (purity) were added.
The treated reinforcing bars were immersed in a latex-containing cement composition consisting of 5 parts of sodium hydroxide, 0.1 parts of caustic soda, and 40 parts of water, and dried at 140°C for 10 minutes. The coating thickness of the obtained anti-corrosion treated reinforcing steel is 3.
It was 50μ.

For comparison, dip-coated coatings were prepared using only water-based paint and latex-containing cement (average dry film thicknesses of 3000 μm and 700 μm, respectively). These rust-proofed reinforcing bars were placed in a formwork, and a light foamed concrete raw material mixture slurry was poured into it, and after foam molding, it was completely cured in an autoclave at 180°C and 10 kg/ctrl.

A part of the obtained 7'-t dunning aerated concrete board was used for promotional trial sales, and a part was used for trial sales to determine the adhesion strength of embedded reinforcing bars to the matrix of lightweight aerated concrete. The corrosion resistance test was carried out by applying a load for 2000 hours using a sunshine weather meter, and then covering the reinforcing bars with a lightweight cellular concrete plate and observing the condition of the reinforcing bars. In addition, the adhesion strength was tested by the pull-out method. The results of these tests are shown in the table. In fact, the rust-proofed reinforcing steel bars were not embedded in the concrete slurry, but were left in a bare autoclave under the same conditions as above. This product was subjected to an accelerated feeding test using the CASS method. CAS S test is A
The time was 500 hours in accordance with STMI3368. The results are also shown in the table.

Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of the case Request No. 58-115448 2, Name of the invention Rust prevention method for reinforcing reinforcing bars for lightweight cellular concrete 3, Person making the amendment Relationship to the case Patent applicant (024) Onoda Cement Co., Ltd. 4, Agent (1 other person) 6. Specification subject to amendment 7, 7ii The following parts of the original specification of contents will be corrected.

(1) 2 negative 20th line 12~477LJ, ``2~4
Correct it to mJ.

(2) On page 3, line 9, "polymer material system" is corrected to "polymer material thread."

(3) 4 JJ 15 (-j "lead tetratrioxide", [
Corrected to trilead tetraoxide J.

(4) On page 5, lines 16-17, change “5-30%” to “5-30%”.
"Within a range of 30%," he corrected.

(5) On page 7, line 5, ``low rust prevention ability'' is corrected to ``decreased rust prevention ability, decreased adhesive strength.''

(6) Page 8] Line 6: ``Correct 5BRJ as ``S BR latex'' a].

(7) Page 9, lines 1-2 [Copolymer emulsion, etc.]
Corrected to "copolymer resin emulsion, etc."

(8) On page 9, line 8, "borotartrate base, etc." is corrected to "borotartrate, etc."

(Page 9111, lines 14-15 [Concrete matrix] is corrected to "Concrete matrix."

oat 12nij Lines 1-12 “(Daiichi Kojoko 4
i1i (1st product name)" is corrected to "(Daiichi Kogyo Seiyaku last product name) 1.5 copies."

Claims (1)

[Claims] A polymer latex containing an inorganic filler is applied and dried to form a film with a thickness of 10 to 500μ, which is adhered to the reinforcing steel.Afterwards, a polymer latex-mixed cement or mortar is applied to the outer periphery of the coating to a thickness of 50μ before drying. A rust prevention method for reinforcing reinforcing bars for foamed concrete, characterized by forming a film of ~2,500μ and a total coating film of 60 to 3,000μ.