JPS6016661A - Deterioration preventing method of reinforced concrete or inorganic material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing deterioration (particularly carbonation) of reinforced concrete structures or inorganic materials such as cement and concrete over a long period of time (semi-permanently).

Reinforced concrete structures are durable composite structures in which the reinforcing bars are protected and rust-proofed in the highly alkaline atmosphere of cement concrete. rusts. When the reinforcing steel rusts, its volumetric expansion pressure causes cracks in the cover concrete, and if further rusting is accelerated by the infiltration of oxygen and moisture through the cracks, the durability of the cover reinforced concrete structure is significantly impaired. Depending on the conditions, such a phenomenon may occur over a short period of time. This is accelerated by fire and exhaust gas, and in marine structures and structures near the seashore due to salt damage, reinforcing bars are prone to corrosion and are subject to rapid damage and deterioration.

In addition, cement concrete I. hardens over a long period of time and turns into rock over time, and its excellent robustness makes it an optimal material for civil engineering buildings. It may deteriorate in a short period of time due to weathering effects such as dissolution, hydration, and running water. Generally, carbon dioxide in the air causes deterioration over a long period of time due to the neutralization effect, but this is accelerated by fire and exhaust gas. Furthermore, cement concrete has the disadvantage that cracks due to drying shrinkage and structural cracks are usually unavoidable in most cases, and cracks can cause a decrease in waterproofness and cause weathering such as carbonation to progress to the inside. Become.

As described above, the deterioration and decrease in durability of reinforced concrete structures or inorganic materials such as cement concrete can lead to dangerous situations that can lead to personal injury if left untreated. Developed a repair method for
Publication No. Il).

However, it is often not easy to repair reinforced concrete once it has deteriorated, and as a result of extensive research into methods that can prevent deterioration over a period (semi-permanently) after construction, the present invention was developed. completed.

That is, this invention
・The surface of an inorganic material made of concrete or a mixture thereof is coated with cement paste containing a polymer dispersion or mortar containing a polymer dispersion, or the surface of the cement paste is further coated with a polymer dispersion. This was developed with the aim of providing a method for preventing the deterioration of reinforced concrete or inorganic materials, which is coated with mortar containing the above paste and/or mortar, and there is no risk of semi-permanent deterioration due to the excellent airtightness and waterproofing properties of these pastes and/or mortar. It is something.

The method for preventing deterioration of reinforced concrete or inorganic materials according to the present invention is usually carried out on inorganic materials (structures) such as reinforced concrete 1, etc., at the same time as newly constructed or shortly after newly constructed. The method of the present invention can be applied not only immediately after new construction to a structure that does not have one, but even after a certain period of time has elapsed.

The cement paste referred to in this invention has a diameter of 0.3 mm.
Refers to a mixed composition of the following aggregate and cement (Portland cement is usually used, but other cements may be used), and particularly good results are obtained when the ratio of the two is in the range of 45:55 to 55:45. . In addition, the polymer dispersion is 5BR, which gives the best results when used in this application.
- In addition to A, ethylene/vinyl acetate worked PVC (ethylene, vinyl acetate, vinyl chloride copolymer emulsion), acrylic-styrene (acrylic ester/styrene copolymer emulsion), acrylic (acrylic acid ester emulsion), ethylene/ Vinyl acetate (ethylene chloride, vinyl acetate copolymer emulsion), 5BR-G (cationic polymerized styrene butadiene copolymer emulsion), Vinyl acetate eBeohe (vinyl acetate/vinyl bar acetate copolymer emulsion powder) , Vinyl acetate skewer and vinyl laurate (powder) are mainly used, but are not limited to these, paraffin emuldigon, asphalt emulsion, rubber asphalt emulsion, epoxy resin emulsion, NBR latex, natural rubber latex, Chloroprene latex and MMA, B, R latex, etc. can also be used. This cement paste usually contains a polymer dispersion with a solid content of 2.
Contains 0 to 8.0%.

Mortar as used in this invention refers to a mixed composition of aggregate with a diameter of 1.2 mm or less and cement (usually Portland cement is used, but other cement 1 may be used)' when the ratio of the two is 75 + A range of 25 to 65'+35 gives particularly good results. The polymer dispersion added to this mortar is the same as that added to the cement paste, and is used in approximately the same amount.

In addition, the cement paste and mortar may contain a commercially available rust preventive agent or activated silica powder (containing 90% or more of Si02, and in addition Ca, O, Fe, 203, MgO1AJ1zO).
In some cases, a mixture containing a and the like with high pozzolan reaction activity is added.

The coating process with these cement pastes and mortar is usually carried out by spraying, and the thickness is several mm or less. and covered with cement paste (Claim 1)
After that, if it is further covered with mortar (Claim 3), it becomes a more complete method of preventing deterioration. In some cases, a polymer dispersion (ethylene/vinyl acetate, acrylic ester, acid polyethylene/asphalt, etc.) is applied as a sealer before the coating step.

Note that, prior to the spraying, various polymer emulsions may be applied as a sealer to the surface of concrete or the like.

Next, regarding the cement paste and mortar containing the polymer dispersion used in this invention, (&) carbonation depth, (b) water absorption rate, (C) weight change rate, (d) presence or absence of crack formation, ( e) presence or absence of alkalinity of reinforcing bar atmosphere mortar, (f) rusting area of reinforcing bars, etc. The results of a comparative test with cement paste and mortar that do not contain polymer dispersion are shown together with the test method.

Table 1 shows the composition of the specimens by numbers in parentheses.

(a) Sample numbers (lot) ~ (109) have a ratio of Portland cement to aggregate with a diameter of 0°3 mm or less of 1; 3 (standard mortar, for comparative testing)
In addition to 5BR-A as a polymer dispersion, ethylene vinyl acetate/vinyl chloride (ethylene, vinyl acetate, vinyl chloride copolymer emulsion), acrylic/styrene (
Acrylic acid ester/styrene copolymer emulsion)
, Aku 1 Nor (acrylic acid ester emulsion), ethylene vinyl acetate (ethylene, vinyl acetate copolymer emulsion), 5BR-CC cationically polymerized styrene phtadiene copolymer emulsion), vinyl acetate/veova (powder), Vinyl vinegarφ
Beopa vinyl laurate (powder) as solid content 3.
Those with 0% additives and those without additives (9 types in total)
It is.

(b) Sample numbers (201) to (209) have a ratio of 1=1 (cement paste) of Portland cement and aggregate with a diameter of 0°3 mm or less, and are as described in (a) above. One with the same polymer disverge rich added and one without additive (9 types in total).

(C) Sample numbers (301) to (309) have a ratio of portland cement to aggregate with a diameter of 1°2 mm or less of 1:2.33 (mortar), which is described in (&) above. One was added with the same polymer dispersion as the other, and one was added without it (9 types in total).

(b) Amount of water added to the specimen M required for slump (35±5) mm according to JIS A 1173 (slump test method for polymer cement mortar) (including water in the polymer disc)
.

(c) Spray phenolphthalein indicator on the neutralization depth fracture surface and measure the area that does not turn red.

(d) Water absorption rate JIS A 6203 (polymer digispersion for cement mixing) The raw drying conditions were 60° C. for 48 hours.

(e) Standard conditions for leaving (standard curing) (f) Carbonation conditions 100% G O24kg/cm after the above standard curing
' and leave it for 5 hours.

(g) Repeated dry immersion test 1 cycle is repeated for 10 times, with 2 days of drying (standing) in air at 60°C and 2 days of immersion in 20°C water or 5% saline.

(H) Weight change rate Measured using a scale that can measure up to 10 mg.

(S) The presence or absence of cracks was visually inspected on a 4 x 4 x 9 cm reinforced steel specimen.

(nu) The presence or absence of alkalinity of the mortar in the reinforcing steel atmosphere depends on the phenolphthalein indicator.

(Rusted area of reinforcing bars) The rust was copied onto a polyethylene sheet, a development diagram was created, and after copying, it was analyzed using a video pattern analyzer.

(Test Results) (a) Carbonation Depth (mm) Table 2 shows the measurement results of the carbonation depth conducted under various conditions (6 types).

Cement paste used in the invention of the present application (sample numbers (102) to (109)) under all conditions.

(202) to (209)) and mortar (sample numbers (302) to (309)) are other than those without polymer dispersion (sample numbers (101), (201)).
) and (301) ), the values are the same or lower, and the airtightness is excellent.

(b) Water absorption rate (%) Table 3 shows the results of the water absorption test.

Table 3 Water Absorption Rate ωO Both the cement paste and mortar used in the present invention have small values on average, and their waterproof properties are impaired.

(C) Rate of weight change Table 4 shows the results of the rate of weight change (%) under various conditions (5 types).

The values of both cement paste i and mortar used in the present invention are small, indicating that the increase in weight due to rusting of reinforcing bars is small.

(d) Presence or absence of crack formation Table 5 shows the visual results of crack formation under various conditions (4 types). Note that + indicates that cracks occurred, and - indicates that no cracks occurred.

The cement paste and mortar used in the present invention both have a small value on average and are excellent in durability.

(e) Presence or absence of alkalinity in mortar in a reinforcing bar atmosphere Table 6 shows the results of examining the presence or absence of alkalinity in mortar in a reinforcing bar atmosphere under various conditions (4 types). Note that the 0 mark indicates that the sample was not neutralized, the Δ mark indicates that it was partially neutralized, and the x mark indicates that it was neutralized.

Table 6: Alkalinity of mortar in reinforcing steel atmosphere (
4) Drying after carbonation treatment - Ratio of cement and aggregate immersed in saline solution l:3
Ratio l:1 Ratio 1:2.33 Diameter of aggregate Diameter of aggregate Aggregate diameter 0.3 mm or less 0.3 mm or less 1.2 mm or less None
Addition × OΔ The cement paste and mortar used in the present invention have a stronger ability to maintain alkalinity around reinforcing bars than other cement pastes and mortar.

(f) Rusted area of reinforcing bars (%) Table 7 shows the measurement results of the rusted areas of reinforcing bars under various conditions (4 types).

Under any conditions, the cement paste and mortar used in the invention of the present application showed good results, with the rusted area of the reinforcing bars being smaller on average than the others.

Comprehensively judging the above test results, the mortar used in the present invention gave the best results in all tests, followed by the cement paste.

Next, examples of the present invention will be shown.

Example 1 Anion type S, B, R, latex was applied to the entire surface of a newly constructed exposed concrete exterior wall after 7 months of concrete pouring.
Cement paste mixed with 2% (cement: sand = 1:l)
) was sprayed to a thickness of 2 mm, and then acrylic enamel was sprayed on top. During the afternoon inspection of construction 1, no abnormalities were found.

Example 2 Anion type S, B, R, latex was applied to the entire surface of a newly constructed exposed concrete exterior wall several months after concrete pouring.
Cement mortar mixed with 1% (cement: sand = 1:2
．． 3) was applied to a thickness of 4 mm using a trowel, and acrylic enamel was sprayed on top. During the afternoon inspection of construction 1, no abnormalities were found.

Example 3 Anion 11 S, B, Ryte was applied to the entire surface of the newly constructed exposed concrete exterior wall months after the concrete was placed.
Cement paste (cement: sand = 1:1) mixed with 7.2% of sand was sprayed to a thickness of 2 mm, and then cement mortar (cement :Sand=1':2.3) was applied with a trowel to a thickness of 4 mm, and then acrylic enamel was sprayed on top. During the afternoon inspection of construction 1, no abnormalities were found.

Claims (1)

[Scope of Claims] ■ Prevention of deterioration of reinforced concrete or inorganic materials characterized by coating the surface of reinforced concrete or inorganic materials made of cement, concrete, etc. or a mixture thereof with a cement paste containing polymer dispersion. Method. ■ A method for preventing deterioration of reinforced concrete or inorganic materials, which comprises coating the surface of reinforced concrete, cement, concrete, etc., or an inorganic material made of a mixture thereof with mortar containing a polymer resin. ■ After coating the surface of an inorganic material made of reinforced concrete, cement, concrete, etc. or a mixture thereof with a cement paste containing a polymer dispersion, the surface is further coated with mortar containing a polymer dispersion. A method for preventing deterioration of reinforced concrete or inorganic materials, characterized by: (2) A method for preventing deterioration of reinforced concrete or inorganic materials according to Claims (1), (2) or (0), wherein the polymer dispersion is an anionically polymerized styrene-butadiene rubber dispersion (csBR-A).