KR20030073649A - Polymer cement composition for preventing corrosion and coating method using it - Google Patents

Abstract

PURPOSE: A polymer cement-based composition for coating reinforcing steel is provided to prevent corrosion of reinforcing steel in cement concrete, and improve durability and impact resistance. CONSTITUTION: The polymer cement-based composition comprises 10-80% of cement, 10-70% of polymer dispersion and 10-60% of water. The corrosion of reinforcing steel is prevented by coating polymer cement slurry comprising 50-100% of a polymer/ cement ratio, 50-200% of a water/cement ratio, 0.01-0.15% (based on the solids of polymer) of antifoaming agent, on the surface of steel in a thickness of 100-500micrometer, and curing at 80deg.C or lower for 2-3days. The used polymer is one or more of fatty acid amide, polyethylene glycol, ester amide, organic phosphate ester, dimethyl polysiloxane, etc., and the polymer is one or more of styrene butadiene rubber latex(SBR), polyacrylic acid ester(PAE), ethylene vinyl acetate(EVA), styrene-butyl acrylate(St/BA), epoxy emulsion, etc.

Description

Polymer cement composition for preventing corrosion and coating method using it}

The present invention relates to a polymer cement composition and a coating method using the same to prevent corrosion of cement concrete reinforcing bars, and more specifically, to prepare a polymer cement composition and then coating it on the reinforcing bar polymer having excellent durability, impact resistance and corrosion resistance It relates to a cement composition and a coating method using the same.

In general, rebar is a mild steel wire that is put as reinforcement in concrete when constructing a reinforced concrete structure.It has a drag on shear, cyclic tension or cyclic load acting on the structure and prevents cracking of the concrete structure to improve its durability and lifespan. Most of the skills are occupied.

When the reinforcing bar is corroded by acid, alkali, or salt, the resistance to external force gradually decreases, and in structures such as bridges in which cyclic loads are continuously applied, reinforcing bar fatigue caused by corrosion and repeated loads increases. This can cause cracks in the bridge and shorten its lifespan, causing serious obstacles. In particular, when reinforced concrete structures are placed in poor environments such as beaches, offshore structures, bridges, and wastewater treatment facilities, the corrosion of the reinforcing bars becomes more severe, and the durability of the structures is significantly reduced.

Therefore, the method of coating the epoxy on the surface of the reinforcing bar to prevent the corrosion of the reinforcing bar is used, but the reinforcing bar coated with epoxy has a low impact resistance, so that the coating part is broken even for slight impact and bending at the site, and adheres to concrete There is also a problem of low grade. In addition, it is difficult to apply to general products except for important processes and structures in the construction site because the additional cost required for the coating is expensive compared to the rebar.

On the other hand, many fine aggregates are used to make cement concrete secondary products, and mainly use the steel sand collected from the river as the fine aggregates. However, as the use of fine aggregates increases due to the strong construction industry, the depletion of river sand is severe, and sea sand, which is an alternative, is used. However, in order to use sea sand, it is necessary to have a proper decontamination treatment facility, and there is a problem that occurs due to salt content, that is, a large problem of corrosion occurs.

In order to solve the above problems, it is to provide a polymer cement-based composition for preventing corrosion of cement concrete reinforcing bars having excellent durability, impact resistance and corrosion resistance by using a composition incorporating a cement mixing polymer with cement.

In addition, by applying the polymer cement composition on the surface of the reinforcing bar is economically inexpensive, and provides a coating method using a polymer cement-based composition for preventing corrosion of cement concrete reinforcing easy to apply.

1 is a photograph of the degree of rust generation according to the immersion of sodium chloride aqueous solution of the present invention

2 is a graph showing the degree of rust generation according to the spray of aqueous sodium chloride solution of the present invention

Figure 3 is a cross-sectional structural view of the test piece for sodium chloride aqueous solution penetration test of the present invention

4 is a graph showing the degree of rust generation according to the sodium chloride aqueous solution penetration test of the present invention

5 is a graph showing the degree of rust generation according to the neutralization promotion test of the present invention

6 shows an autoclave curing cycle of the present invention.

In order to achieve the above object, the present invention has a polymer cement ratio of 50 to 100%, a water cement ratio of 50 to 200%, and an antifoaming agent of 0.01 to 015% with respect to the polymer solids to form a polymer cement slurry, which is formed on the surface of circular and deformed steel bars. It is cured by applying to 100㎛-500㎛.

If the polycement ratio is less than 50%, cracking is likely to occur, and since the rebar is to be applied to a predetermined thickness at 100% or more, there is a problem in that it is repeatedly applied three or more times.

The curing method is just left at room temperature, and curing at high temperature for fast curing.

At this time, since the polymer is mixed in the slurry, the polymer hardens to form a film to slow cement hardening. Of course, there is a slight difference depending on the type of polymer, but usually left at room temperature for 24 hours, the applied slurry may be completely hardened, and some types are basically cured for 2-3 weeks.

However, at high temperatures, the polymer is weak to heat, so it must be cured at 80 ℃ or lower and it will cure in about 2 to 3 days.

Hereinafter, the present invention will be described in detail.

The polymer cement composition for preventing corrosion of the present invention is 10 to 80% of cement, 10 to 70% of polymer dispersion glass, and 10 to 60% of water, and an antifoaming agent controls the polarity and molecular weight (molecular weight distribution) of the polymer so that It is necessary to make and use a proper balance between solubility. Also, polymer antifoaming agents have properties that do not stabilize bubbles even when they are very compatible. High fatty acid amide, high molecular weight polyethylene glycol, fatty acid lower alcohol ether, polypropylene glycol, ester amide of higher fatty acid, ester of organic phosphate, metal of higher fatty acid Stone gum, tall oil, silicone, non-silicone, dimethyl polysiloxan e), hydrophobic silica, and the like, mineral oil and lower alcohol are used as carrier components.

The silicone antifoaming agent here is a solution of polysiloxane having a very low surface tension of the active ingredient. When selecting such a polysiloxane, its chemical structure is a very important criterion. Short chain polysiloxanes, such as, for example, those used as surface control additives, are not good because they stabilize bubbles rather than destroy them.

That is, low molecular weight silicon acts as a bubble stabilizer, and as the molecular weight increases, the high molecular weight silicon becomes incompatible enough to cause cratering phenomena. It is not good as antifoaming agent.

Therefore, in order to control the compatibility and solubility of polysiloxane, the molecular weight of the silicone and the chain length are used to change the compatibility by modifying various organic chains in the silicone body, and when adding a polyether chain, Increasing compatibility.

Polymers for cement admixture include styrene budadiene rubber latex (SBR), polyacrylic acid ester (PAE), ethylene vinyl acetate (EVA), styrene-butyl acrylate (St / BA), acrylic emulsion (PA), epoxy emulsion and the like. .

In addition, cement is used as portland cement, special cement, mixed cement.

The polymer cement composition blended as described above is applied to the surface of circular and deformed rebars with a coating thickness of 100 μm-500 μm and cured until the slurry on the surface solidifies at room temperature (20 ° C.) and below 80 ° C. for curing the slurry. do. In this case, a method of coating on the surface of the reinforcing bar by depositing the reinforcing bar in the polymer cement slurry, spraying through a pressure nozzle, a method such as applying with a brush or the like is used.

Reinforcing bars processed as described above are used in cement concrete secondary products such as centrifugal reinforced concrete pipes (aka fume pipes), water pipes, concrete piles, and telephone poles, together with seawater that has not undergone decontamination treatment, to reduce the occurrence of corrosion caused by salinity. Can be.

Test Example 1: Water Resistance Test

After the polymer cement of the present invention was applied to the reinforcing bars, the water resistance of the cured and uncoated reinforcing bars was examined. After immersion in general tap water for 7 days, 14 days, and 28 days, the degree of rust occurrence of the steel bars was observed. .

As a result, the reinforcing bars usually rust on the entire surface of the reinforcing bar in 14 days, the reinforcing bar coated with the polymer cement of the present invention can be seen that no rust after 28 days.

Test Example 2: Observation of Rust by Soaking Application Method

The polymer cement of the present invention is prepared by differently from styrene butadiene rubber latex (SBR), polyacrylic acid ester (PAE), ethylene vinyl acetate (EVA), styrene-butyl acrylate (St / BA), acrylic emulsion (PA), epoxy emulsion Then, it was applied to the reinforcing bar, and then to determine the degree of rust generation for the reinforcing and non-coated reinforcing bar, soaked in sodium chloride (Nacl) 10% aqueous solution for 28 days, the results are shown in FIG.

As shown in Figure 1, the general reinforcing bar (two on the right), which was not applied after soaking in a 10% aqueous solution of sodium chloride (Nacl) for 28 days, was rusted in front of the reinforcing bar. Rebar) can be seen that no rust occurs after 28 days.

Test Example 3 Observation of Rust Occurrence by Spray Application of Aqueous Sodium Chloride Solution

The polymer cement slurry of the present invention is prepared by using styrene-butyl acrylate-1 (St / BA-1), styrene-butyl acrylate-2 (st / BA-2), or an acrylic emulsion (PA), and applying it to reinforcing bars. Then prepare hardened and uncoated bars. An aqueous solution spray device for the reinforcing bar was sprayed with a 10% aqueous solution of sodium chloride to the surface of the reinforcing bar, and the degree of rust generation of the bar is shown in FIG. At this time, the conditions of the test equipment is 1.0 kg / ㎠ spray pressure, maintaining the wet temperature of 47 ℃, spray test for 24 hours, 48 hours.

As a result of the experiment of Figure 2, unapplied rebar (Plain) was rust of 78% at 24 hours, 100% at 48 hours, while rebar coated with the polymer cement slurry of the present invention was about 3% rust occurred.

Test Example 4: Salt Penetration Test

The polymer cement slurry of the present invention is prepared by differently using styrene-butyl acrylate-1 (St / BA-1), styrene-butyl acrylate-2 (st / BA-2), or acrylic emulsion (PA), which is applied to rebar. Then, the penetration rate of the cured and ordinary reinforcing bars in a 10% aqueous solution of sodium chloride (Nacl) was examined for rust formation.

Sodium chloride 10% aqueous solution penetration test specimen was prepared by mixing the cement ratio of 30% water cement: standard yarn = 1: 3 (weight ratio) as shown in Figure 3 below, the cement mortar, and coated with reinforcing bars coated with a polymer cement composition in the center Test pieces are made by inserting reinforcing bars.

After curing the prepared test piece for 28 days, infiltrated with a 10% aqueous solution of sodium chloride for 24 hours at 10 atm, the test piece was taken out and dried at 60 ℃ for 24 hours. After repeating the above procedure 5 times and 10 times, the degree of rust generation on the surface of the rebar was observed, and the results are shown in FIG. 4.

As shown in FIG. 4, corrosion of reinforcing bars not applied to all five and ten times was found to be remarkable, but reinforcing bars coated with the polymer cement composition exhibited a slight occurrence of rust.

Test Example 5: Neutralization Promotion Test

After the salt penetration test of Test Example 4, in order to determine the degree of rust generation for the neutralization promotion test, using a neutralization promotion test apparatus tested under the conditions of temperature 30 ℃, humidity 60% RH, CO 2 concentration 5%, The procedure was repeated five times and ten times, respectively, and the results are shown in FIG. 5.

As shown in Figure 5, the unreinforced reinforcing bar significantly increased the occurrence of rust, the reinforcing bar coated with polymer cement sludge showed a very fine increase.

Test Example 6: Autoclave accelerated curing test

The polymer cement slurry of the present invention is prepared by differently using styrene-butyl acrylate-1 (St / BA-1), styrene-butyl acrylate-2 (st / BA-2), or acrylic emulsion (PA), which is applied to rebar. Next, test specimens were prepared for the reinforcing bars and the non-coated bars as shown in FIG. 3 to examine the degree of rust generation of the bars due to autoclave-promoting curing.

When preparing the test piece, sodium chloride was mixed with 0%, 0.02%, 0.04%, 0.1%, 0.135% and 0.27% with respect to the dry weight of the fine aggregate, and the reinforcing bar coated with the polymer cement composition and the uncoated bar were placed in the center of the test piece. A test piece was produced.

The prepared test piece was cured for 28 days, and was carried out eight times by the curing method as shown in FIG. 9 at 180 ° C. and 10 atm using an autoclave curing machine. The results are shown in FIG. 6.

As shown in Figure 6, the unreinforced ordinary reinforcing bar is more severe in the occurrence of rust as the salt content increases, while the rebar coated with polymer cement slurry was slightly rust when the sodium chloride is more than 0.04%, but the degree is very The fineness can be seen.

As described above, by coating the polymer cement for the corrosion protection of the cement concrete reinforcement according to the present invention on the surface of the reinforcement to improve the durability, impact resistance and corrosion resistance. In addition, the reinforcing bar and sea sand coated with the polymer cement composition are used in a cement concrete secondary product without decontamination, and thus, have excellent resistance to corrosion and greatly extend the life of the product. In addition, by using the sea as it is, there is no need for decontamination facilities and management, there is an economic effect.

While the invention has been shown and described with respect to particular embodiments, it will be appreciated that the invention can be varied and modified without departing from the spirit or scope of the invention as set forth in the claims below. It will be appreciated that those skilled in the art can easily know.

Claims (4)

In coatings composed of cement, polymer dispersion, and water, the polymer cement ratio is 50 to 100%, the water cement ratio is 50 to 200%, and the antifoaming agent is 0.01 to 0.15% based on the polymer solids. The coating method characterized in that the coating on the surface of the deformed steel reinforcement with 100㎛-500㎛ to prevent corrosion of cement concrete rebar. The method of claim 1, The cement admixture polymer is one of styrene butadiene rubber latex (SBR), polyacrylic acid ester (PAE), ethylene vinyl acetate (EVA), styrene-butyl acrylate (St / BA), acrylic emulsion (PA), epoxy emulsion The coating method characterized in that to prevent the corrosion of the cement concrete reinforcement using a mixture of two or more. The method of claim 1, Antifoaming agents include higher fatty acid amides, higher molecular weight polyethylene glycols, fatty acid lower alcohol ethers, polypropylene glycols, ester amides of higher fatty acids, organic phosphates, metal stone gums of higher fatty acids, and tall oils. , Silicone, non-silicone, dimethyl polysiloxane (dimethyl polysiloxane), hydrophobic silica mineral oil, a coating method, characterized in that to prevent corrosion of cement concrete reinforcement, characterized in that the mixture of one or two or more of the lower alcohol. The coating method according to claim 1, wherein the coating material is mixed with 10 to 80% of cement, 10 to 70% of polymer dispersion, and 10 to 60% of water. .