JPH0512309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a surface layer modifier for use in repairing degraded parts of reinforced concrete structures or inorganic materials such as cement and concrete, and a method of using the same.

(Prior technology) Reinforced concrete structures are composite and durable structures in which reinforcing bars are protected and rust-proofed in the highly alkaline atmosphere of cement concrete, but the concrete itself deteriorates over time due to carbon dioxide in the air. The reinforcing steel becomes rusty. When the reinforcing steel rusts, its volumetric expansion pressure causes cracks in the cover concrete, and the penetration of oxygen and water through the cracks further accelerates rusting. This repeated action causes the cover concrete to peel off, resulting in a significant loss of durability of the reinforced concrete. In addition, structures located near the sea are subject to damage and deterioration more quickly because their reinforcing bars are prone to corrosion.

Cement-based hardened products such as concrete and mortar are widely used in the civil engineering and construction fields, but these hardened inorganic materials have countless micropores.
As time passes, the surface layer gradually deteriorates. This generally deteriorates due to the neutralization effect of carbon dioxide gas in the air over a long period of time. In other words, carbon dioxide gas in the air acts on the hydrogenated lime and water contained in the inorganic material to produce carbonated lime (CaCO ₃ ) or bicarbonate lime (Ca(HCO ₃ ) ₂ ), and water acts on this. This leads to lime diversion and neutralization of inorganic materials. Expressing this in the formula: 2Ca(OH) ₂ +H ₂ O+3CO ₂ →CaCO ₃ +Ca
(HCO ₃ ) ₂ +2H ₂ O.

Furthermore, cement concrete has the disadvantage that it is subject to cracks due to drying shrinkage and structural cracks, and these cracks reduce waterproofing, as well as rusting of reinforcing bars due to acid rain and neutralization of concrete due to carbon dioxide gas, which have recently become a problem. Weathering such as oxidation will progress to the inside of the structure.

In this way, if left untreated, the deterioration and decrease in durability of hardened inorganic materials such as reinforced concrete structures and cement concrete can lead to dangerous situations that can lead to personal injury. There is a demand for repair agents and methods.

Conventionally, in order to strengthen and activate the deteriorated surface layer, the repair of reinforced concrete structures has been carried out by applying anti-corrosion paint to the exposed reinforcing bars, and applying a combination of alkali metal silicate and ammonium silicate compound. The use of special colloidal silica by lamination (Special Publication No. 19609/1983) and surface strengthening methods by coating and impregnating with water-soluble silicate compounds, etc.
It is known that the surface is treated with a penetrating coating agent to block the penetration of water and oxygen from the outside, thereby exhibiting a deterioration prevention effect.

In addition, the repair method is as shown in Figure 2 A: The concrete in the repaired area is removed to expose the reinforcing bars, and the reinforcing bars are cleaned (rust removed) and cleaned.

Brush anti-rust paint onto the reinforcing steel.

A polymer cement mortar repair agent involves applying an inorganic aqueous solution as a neutralization inhibitor or waterproofing agent to the deteriorated concrete surface.The repair work is completed by repairing the sagging parts, applying an intermediate coat, and then applying a top coat. .

(Problems to be Solved by the Invention) However, although the use of special colloidal silica made by combining the above-mentioned alkali metal silicate and ammonium silicate compound has good durability and weather resistance, the molar ratio of SiO ₂ is low. Since it is not large and highly alkaline, its ability to recover alkalinity in the neutralized part is small, and since it is a colloidal particle, its ability to penetrate inside concrete is also smaller than that of water-soluble particles. In the surface strengthening method by coating and impregnating a water-soluble silicate compound, the durability after curing is poor and the effect is lost due to elution over a long period of time. Furthermore, since a polymer-based repair agent is used, there is a problem in that it does not adhere well to the concrete surface.

In addition, conventional repair methods require the steps described above, and also require the preparation of rust inhibitors, neutralization inhibitors, and waterproofing agents, which are time-consuming. .

Therefore, the present invention mixes a rust preventive agent and a neutralization inhibitor into a polymer emulsion to create a repair agent with excellent durability and waterproof properties, and also a coupling agent that improves the adhesion between concrete and polymer repair agent. The purpose is to provide a surface layer modifier for reinforced concrete or inorganic materials by mixing it with the repair agent, and furthermore, by using the surface layer modifier, the repair process can be reduced and work efficiency can be improved. The purpose is to

(Means for Solving the Problems) The gist of the present invention for solving the above problems and achieving the objects is that water-soluble silicate, nitrite, and a silane coupling agent are mixed into a polymer emulsion. A water-soluble It is characterized by applying a surface layer modifier made by mixing silicate, nitrite, and silane coupling agent into a polymer emulsion, impregnating it into the reinforced concrete or inorganic material body, and then applying intermediate coating and top coating. It consists in a method of repairing reinforced concrete or inorganic materials.

(Function) When the surface layer modifier according to the present invention is applied, the following effects occur.

First, the water-soluble silicate compound mixed into the polymer emulsion as a neutralization inhibitor is a water-soluble silicate compound that is produced when tricalcium silicate or dicalcium silicate in reinforced concrete components reacts with water and is hydrolyzed. Reacts with calcium oxide.

Expressing this in a formula, the reaction formula for hydrolysis is 2×3CaO・SiO ₂ +nH ₂ O →3CaO・2SiO ₂ nH ₂ O+3Ca(OH) ₂ 2×2CaO・SiO ₂ +nH ₂ O →3CaO・2SiO ₂ nH ₂ O + Ca (OH) ₂ , 3CaO・SiO ₂ in the formula is tricalcium silicate, and n
is an integer, and 2CaO・SiO ₂ is dicalcium silicate.

Calcium hydroxide (Ca(OH) ₂ ) produced by the above hydrolysis reacts with silicon dioxide contained in the water-soluble silicate compound to produce lime silicate.

This can be expressed as follows: XCa(OH) ₂ +YSiO ₂ .nH ₂ O →XCaO.YSiO ₂ nH ₂ O X and Y in the formula are coefficients that change depending on the molar ratio of the water-soluble silicate compound. n is an integer.

Since this silicate lime salt XCaO YSiO ₂ nH ₂ O grows into large crystals, it can penetrate into cracked parts of reinforced concrete and densely fill the cracked parts, thereby removing moisture from the outside air. This prevents penetration.

Next, nitrite, which is mixed into the polymer emulsion as a rust inhibitor for reinforcing bars, forms an oxide film on the surface of the reinforcing bars.

In other words, nitrite ions (No ₂ ^- ) and ferrous ions (Fe ²⁺ ) of the reinforcing steel react to form an oxide film, which can be expressed in the formula: 2Fe ²⁺ +2OH ^- +2NO ₂ ^- →2NO+Fe ₂ O ₃ + H ₂ O. Fe ₂ O ₃ in the formula is an oxide film that forms a strong film on the iron surface.

Next, the silane coupling agent, which is mixed into the polymer emulsion as an adhesive, has organosilanol groups that chemically bond organic polymers with inorganic materials such as sand, coal, glass, and metal. A silicon-containing monomer,
It is represented by the general formula Rn・Si(OH) _4-o . Rn here
is an organic group that reacts with thermoplastic or thermosetting resins.

Therefore, the adhesion between the concrete and the polymer repair agent in the reinforced concrete repair area is further strengthened.

Furthermore, in order to repair a deteriorated part of reinforced concrete using a surface layer modifier obtained by mixing the above-mentioned neutralization inhibitor, rust preventive agent, and adhesive strengthening agent into a polymer emulsion, first, the above-mentioned repair is carried out. After cleaning the area, the surface layer modifier is applied, followed by intermediate coating and top coating to complete the repair work. Therefore, if the surface layer modifier according to the present invention is used, it is not necessary to prepare and apply a rust preventive paint or a neutralization inhibitor, and it can be done in one operation as a surface treatment agent. It is something.

(Example) To generate the surface layer modifier 3 for reinforced concrete or inorganic materials according to the present invention, potassium silicate with a molar ratio (SiO ₂ /K ₂ O) of 2.6 was prepared as a water-soluble silicate compound. The potassium silicate was adjusted to 10% by weight based on the water content of the polymer emulsion as 100. Next, calcium nitrite (Ca(NO) was used as the nitrite for rust preventive. ₂ ) ₂ ), and the calcium nitrite is added to 100% of the water content in the polymer emulsion.
The amount of water in the polymer emulsion was adjusted to 30% by weight, and a silane coupling agent containing a silicon-containing monomer was used as an adhesive.
It is used at a concentration of 1% by weight based on 100% solid content, together with the above potassium silicate and calcium nitrite.
20% of the polymer emulsion.

In this example, potassium silicate, calcium nitrite, and a silane coupling agent were mixed into the polymer emulsion as described above, but the mixture is not limited to this. Calcium can also be used as long as it does not cause abnormalities when mixed into the polymer emulsion, and the amount of calcium added is 1 to 10 per 100 of the water content in the polymer emulsion.
It suffices if it is % by weight. In addition, nitrite is not particularly limited as long as it does not cause any abnormality when mixed into the polymer emulsion, but it may be one that does not cause salt damage, and the amount of nitrite added should be within the range of 100% water content in the polymer emulsion. The amount may be 1 to 30% by weight.

In addition, the solid content of polymer emulsion is 5~
It should be 20%.

In this example, when potassium silicate, calcium nitrite, and a silane coupling agent were mixed into the polymer emulsion, no particular abnormality was observed.

Next, a method for repairing reinforced concrete 1 will be explained with reference to FIGS. 1 and 2. Reference numeral 2 indicates reinforcing bars, 3 indicates neutralized concrete, and 4 indicates a surface layer modifier.

This surface layer modifier was applied to the deteriorated parts of the reinforced concrete using a brush after cleaning and cleaning according to the procedure shown in Figure 2B. Then, the repair work was completed by applying intermediate coat 5 and top coat 6 with cement mortar.

After this, there were no cracks in the repaired area.
In addition, the progress of carbonation inside the concrete was inhibited by the lime silicate salt 7 densely filled in the cracks, which prevented moisture from penetrating.

(Effects of the Invention) As explained above, the surface layer modifier according to the present invention is made by mixing a water-soluble silicate compound, nitrite, and a silane coupling agent into a polymer emulsion. This eliminates the need to separately prepare a neutralization inhibitor, a rust preventive agent, and an adhesive strengthening agent, and by using the surface layer modifier in repair work, rust prevention can be achieved. It is possible to omit the steps of applying a neutralization inhibitor and applying a neutralization inhibitor, thereby simplifying the labor and effort of repair work.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the surface modifier according to the present invention applied to a repaired part of reinforced concrete;
The figure is a block diagram showing the repair process. 1...Reinforced concrete, 2...Reinforced steel, 3...
Concrete, 4...Surface layer modifier, 5...Intermediate coating, 6...Top coating.

Claims (1)

[Scope of Claims] 1. A surface layer modifier for reinforced concrete or inorganic materials, characterized in that a water-soluble silicate compound, nitrite, and a silane coupling agent are mixed into a polymer emulsion. 2 Deteriorated reinforced concrete or cement;
After removing rust from the repaired part of an inorganic material made of concrete or a mixture thereof and cleaning it, a water-soluble silicate compound, nitrite, and a silane coupling agent are mixed into a polymer emulsion. A method for repairing reinforced concrete or inorganic materials, which comprises applying a surface layer modifier, impregnating the main body of reinforced concrete or inorganic materials, and then applying intermediate coating and top coating.