JPS6016654A - Surface finish of concrete - 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 finishing a concrete surface having a coating layer with good weather resistance on the surface.

Reinforced concrete structures are composite, durable 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 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 water addition and running water effects. Generally, carbon dioxide in the air causes deterioration over a long period of time due to the neutralization effect, but fire and exhaust gas accelerate the deterioration. 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 restoration method (Special Publication No. 57-11988)
Publication No.).

However, it is often not easy to repair reinforced concrete or the like once it has deteriorated. Therefore, it was discovered that if the surface of a newly constructed concrete structure is coated with mortar containing polymer dispersion in advance, deterioration can be prevented over a long period (semi-permanently) of the construction diameter, so this coating process is possible. The present invention was completed as a result of research into a method that could be carried out as easily as possible.

That is, this invention covers a desired portion of the inner wall of a formwork assembled into a desired shape with a thin plate molded with mortar containing a polymer dispersion, and then pours concrete to bond the thin plate and concrete. This was developed with the aim of providing a finishing method for concrete surfaces that is molded as one piece so that at the same time as the construction of the main body, the surface is covered with a coating layer of mortar containing a highly weather-resistant Shokai/Children dispersion. It is.

The concrete surface finishing method according to the present invention can be effectively used at both concrete construction sites and PC component manufacturing plants.

Mortar as used in this invention refers to a mixed composition of aggregate and cement (Portland cement is usually used, but other cements may be used), and the ratio of the two is 75:
The ratio is in the range of 25 to 45:55, and particularly good results are obtained when the ratio is in the range of 75:25 to 85:35.

What is the polymer dispersion added to this mortar?
In addition to 5BR-A, which gives the best results when used in this application,
Ethylene/vinyl acetate/PVC (ethylene, vinyl acetate, vinyl chloride copolymer emulsion), acrylic/styrene (styrene copolymer emulsion of acrylic acid ester),
Acrylic (acrylic acid ester emulsion), ethylene/vinyl acetate (ethylene, vinyl acetate copolymer emulsion), 5BR-C (cationic polymerization styrene butadiene copolymer emulsion), vinyl acetate/beova (vinyl acetate/vinyl peracetate copolymer emulsion) Vinyl laurate (powder) is mainly used for vinyl acetate ◆ Beoba, but it is not limited to these, and includes paraffin emulsion, asphalt emulsion, rubber asphalt emulsion, epoxy resin emulsion, N
BR latex, natural rubber latex, chloroprene latex, MMA, B, R latex, etc. can also be used. This mortar usually contains a polymer dispersion with a solid content of 2.0 to 8.0%.
Use by mixing.

In addition, the mortar contains a commercially available rust preventive agent or activated silica powder (Sing) in an amount of 90% or more, and also contains CaO1F.
A mixture containing high pozzolan reaction activity, such as MgOlA2.03, MgOlA2.03, etc.) may be added.

The thin plates molded with mortar containing the polymer dispersion used in this invention are usually produced by pressurization, extrusion or casting together with suitable reinforcing materials (for example am), and are usually 15 mm or less. Then, if necessary, a pattern (decoration) is formed on one side of this thin plate (the side that comes into contact with the formwork), and unevenness (sole) is formed on the other side, so that the concrete surface can be improved. A decorative process can be omitted, and adhesion to the concrete body can be improved. At this time, the particle size of the mortar aggregate containing the polymer dispersion used is selected to be an appropriate particle size according to the thickness of the board.

Next, regarding the mortar containing the polymer dispersion used in this invention, (a) neutralization depth, (b) water absorption rate, (C) weight change rate, and (d) i.e. Table 1 shows the values of the specimens. The composition is indicated by numbers in parentheses. (a) Sample numbers (101) to (109) have a ratio of portland cement to aggregate with a diameter of 0°3 mm or less of 1:3 (standard mortar), and in addition to 5DR-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) (emulsion), acrylic (acrylic ester emulsion), ethylene/vinyl acetate (ethylene, vinyl acetate copolymer emulsion), 5D
R-C (cationic polymerized styrene-butadiene copolymer emuldimine), vinyl acetate beoba (powder), vinyl acetate/veoba/vinyl laurate (powder) added at a solid content of 3.0% each, and additive-free. (9 types in total).

(b) Sample numbers (201) to (209) have a ratio of 1=1 between Portland cement and aggregate with a diameter of 0°3 mm or less, and are treated with the same polymer disverger as described in (a) above. There are 9 types in total: those with and without addition of radish.

(C) Sample numbers (301) to (309) have a ratio of portolan lower cement to aggregate with a diameter of 1°2 mm or less of 1:2.33, and the samples shown in (a) above have a ratio of l:2.33. One was added with the same polymer Disverge 1, and the other was not added (9 types in total).

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

(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 mixing with cement) The drying conditions were set to 60° C. for 48 hours.

(e) Standard conditions for leaving (standard curing) (e) Conditions for carbonation: After the above standard curing, leave at 100% CO4 kg/cni' for 5 hours.

(g) Dry immersion repeated test 60°C drying (standing) in air for 2 days and 20°C water or 5 days
% saline solution for 2 days, and this cycle is repeated 10 times.

(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 4x4x9cm reinforcing 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).

All of the mortars used in the present invention have a small value on average and are excellent in waterproofness.

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

All of the mortars used in the present invention have small values, indicating that there is little increase in weight due to rusting of reinforcing bars.

(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, or - indicates that no cracks occurred.

Table 5 Presence or absence of cracks (1) After drying from standard condition - Immersion in water Table 5 Presence or absence of cracks Z (All mortar used in the claimed invention have no cracks on average and are excellent in durability.

e) Alkalinity of mortar in reinforcing bar atmosphere Table 6 shows the results of examining the presence or absence of alkalinity in mortar in reinforcing bar atmosphere under various conditions (4 types). The mark "X" indicates that the material was partially neutralized.

The mortar used in the present invention has a stronger ability to keep the area around the reinforcing bars alkaline than other 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 mortar used in the invention of the present application shows good results, with the rusted area of the reinforcing bars being smaller on average than other mortar.

Comprehensive judgment of the above test results shows that in all tests, the mortar used in the present invention has outstanding effects compared to those that do not contain polymer dispersion, and is especially effective for bones with a diameter of 1.2 mm or less. Mixed compositions of wood and cement (with ratios between 75:25 and 65:35, listed in the left column of the tables above) give the best results.

Example (1) Polymer cement mortar I&L [Cement: Aggregate (1.2 mm or less): Vinyl fiber: 5BR-A latex (solid content 23.5%) = 30 Nia 0:0.5:16
] was poured into a mold having an uneven bottom surface, left at room temperature for 3 hours, steam-cured for 3 hours, and naturally cured for 6 days to form a mold with soles 2 on the back and surface as shown in the drawing (cross-sectional view). 90cm x 180cm x with notches 3 (joints) around the surface
A 1.2 cm thin plate was manufactured in-house.

When this thin plate was poured into concrete on site, the attached concrete was placed on the inner surface of the concrete form, integrating the thin plate and concrete. After removing the formwork, the joints formed by the joints of the thin plates were filled with mortar having the same composition as the thin plates. One week after filling the joints with mortar, JIS A 691 was applied to the entire exterior wall.
0 Multi-layer pattern spray material C was sprayed to apply makeup.

When this building was inspected one year after construction, no abnormalities were found.

Example (2) A thin plate with a thickness of 4 mm was manufactured in the same manner as in Example (1). When pouring concrete in the PC factory, these thin plates are lined up on the bed surface of the concrete form, and concrete is poured.
Steam curing was carried out using the usual method, and the thin plate and concrete were integrated. After removing the formwork, the joints formed by the joints of the thin plates were filled with mortar having the same composition as the thin plates. The joints were filled with mortar for one week, and the PC panels covered with thin sheets were brought to the site and erected. After the PC panel installation is completed and the sealing work is completed, JIS A 6910 multi-layer pattern sprayed material C is applied to the entire exterior wall.
I applied makeup by spraying it on.

When this building was inspected one year after construction, no abnormalities were found.

As described above, according to the concrete finishing method according to the present invention, a coating layer of mortar containing a polymer dispersion with good weather resistance can be formed on the surface of the concrete at the same time as the construction of the main body. Not only is construction extremely easy, but even when reinforcing bars are placed in concrete, the reinforcing bars are reliably protected by the thin plates and are not exposed, making it possible to obtain extremely durable concrete structures. .

[Brief explanation of the drawing]

The drawing is a cross-sectional view of a sheet of polymer cement mortar composition. l...thin plate, 2... sole, 3... notch (joint).

Claims (1)

[Claims] ■ After covering a desired portion of the inner wall of the formwork assembled into a desired shape with a thin plate molded with mortar containing a polymer dispersion, concrete is poured and the thin plate and concrete are injected. A concrete surface finishing method characterized by integrally molding. (2) The method for finishing a concrete surface according to claim 0, wherein the polymer dispersion is an anionically polymerized styrene butadiene rubber dispersion (SBR-A).