JPS6030763A - Mold frame for finishing concrete surface - 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 formwork for finishing a concrete surface that forms a coating layer with good weather resistance on the concrete surface during concrete pouring. .

Reinforced Concrete 1. Structures are durable composite structures in which the reinforcing steel is protected and rust-proofed in the highly alkaline atmosphere of cement concrete, but the concrete itself is damaged over a long period of time due to charcoal gas in the air, etc. The reinforcing steel becomes rusty. When the reinforcing steel rusts, the volumetric expansion pressure causes the cover concrete to rust.
If cracks occur in the steel and further rusting is promoted due to the infiltration of oxygen and moisture through the cracks, the durability of the reinforced concrete structure will be 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 hydration and lithium water effects. Generally, charcoal gas in the air causes carbonation and deterioration over a long period of time, but this is accelerated by fire and gas. Furthermore, cement concrete has the disadvantage that cracks due to drying shrinkage and structural cracks are usually unavoidable in most cases, and if cracks occur and the waterproofness decreases, weathering such as carbonation will progress to the inside. It turns out.

In this way, the deterioration of inorganic materials such as reinforced concrete 1, structures or 7-ment concrete 1, etc., and the decrease in their durability, if left untreated, will lead to a dangerous situation that may lead to personal injury, so the inventors We first developed a method for repairing reinforced concrete or inorganic materials (Special Publication Publication No. 57-119).
Publication No. 88).

However, it is often not easy to repair reinforced concrete or the like once it has deteriorated. Therefore, it was discovered that deterioration could be prevented over a long period of time (semi-permanently) by coating the surface of newly constructed concrete structures with mortar containing a polymer dispersion. The present invention was completed as a result of research into a method to make the process as easy as possible.

That is, the present invention provides a formwork for finishing a concrete surface molded with mortar containing a polymer dispersion instead of the conventionally used metal plate or plywood, and uses this formwork for finishing concrete surfaces. It was developed with the aim of forming a structure in which the mold and the main body are integrated into one body, forming a structure having a coating layer with good weather resistance on the surface of the main body.

The formwork for finishing concrete surfaces according to the present invention includes:
At a construction site, if concrete is placed in the desired shape (MU standing) and then poured and cured, there is no need to remove the formwork as in the past, and the surface of the concrete remains unchanged. It's a good thing.

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 65:35.

What is the polymer dispersion added to this mortar?
In addition to S and BR-A, which give the best results when used in this application, ethylene/vinyl acetate/vinyl chloride (ethylene, vinyl acetate, vinyl chloride copolymer emulsion), acrylic/styrene (acrylic acid ester/styrene copolymer emulsion) ), acrylic (acrylic acid ester emulsion), ethylene/vinyl acetate (ethylene, vinyl acetate copolymer emulsion), 5BR-C (cationically polymerized styrene butadiene copolymer emulsion), vinyl acetate (vinyl acetate emulsion), vinyl peracetate copolymer emulsion powder)
, vinyl acetate/he/he/vinyl laurate (powder) is mainly used, but is not limited to these, paraffin emulsion, 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 mortar usually contains a polymer dispersion with a solid content of 2.0 to 8.0.
% and used.

In addition, the mortar contains a commercially available rust preventive agent or activated silica powder (90% or more of Sj02), and in addition, Cab, F.
A mixture containing e2O3, MgO, A12ha, etc. with high pozzolan reaction activity) may be added.

The mold molded with mortar containing the polymer dispersion used in this invention is usually manufactured by pressurization, extrusion, or casting together with a suitable reinforcing material (for example, fiber), and is usually 15 mm or less, but especially The thickness is not limited. Then, if necessary, a pattern (decoration) is formed on one side of this formwork (the outside when the formwork is installed), and unevenness (sole) is formed on the other side. , it is possible to omit the decoration process of the concrete surface and to improve adhesion to the concrete body. Further, 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 formwork.

Next, regarding the mortar containing the polymer dispersion used in this invention, (a) neutralization depth, (b) sucking density, (C) weight change rate, (d) presence or absence of crack formation,
(e) Presence or absence of alkalinity of mortar in the reinforcing steel atmosphere, (f)
The results of a comparative test on the rusted area of reinforcing bars, etc. with mortar that does not contain polymer dispersion are shown in Table 1 (hereinafter referred to as "clothes" are collectively shown at the end of the Detailed Description of the Invention column) along with the test method. .

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

(a) Sample numbers (lot) ~ (109) have a ratio of Portland cement and aggregate of 0°3 mtn or less in diameter of 1:3 (standard mortar), and 5BR as a polymer dispersion is added to this. - In addition to A, ethylene/vinyl acetate/vinyl chloride copolymer emulsion (ethylene, vinyl acetate, vinyl chloride copolymer emulsion), acrylic/styrene (styrene copolymer emulsion in acrylic butyester), acrylic (acrylic acid ester emulsion), ethylene・Vinyl acetate (ethylene, vinyl acetate copolymer emulsion),
5BR-C (cationic polymerized styrene-butadiene copolymer emulsion), vinyl acetate, vinyl laurate (powder), 3.0% solid content of vinyl acetate, vinyl laurate (powder), and These are additives (9 types in total).

(b) Sample numbers (201)-(209)-c are shown in which the ratio of Portland cement to aggregate with a diameter of 0°3 mm or less is ■:■, and the same polymer as described in (a) above is used. One with added dispersion and one without additive (9 types in total).

(C) Sample numbers (301) to (309) are Portland cement and have a diameter of 1°2 mm!
! The ratio with the lower aggregate is 1:2.33, and the above (a)
) with and without the same polymer dispersion (9 types in total).

(b) Amount of water added to the specimen Amount required to achieve a slump of 35 ± 5 mm (including water in the polymer dispersion) according to JIS A 1173 (Pol) Marseme 75 mo Ay Tal slump test method).

(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° and 48 hours.

(e) Standard storage conditions (standard curing) 20℃, 90%
2 days at RH → 511 in water at 20°C → R1 at 20°C and 60% (21 days.

(f) Carbonation conditions f) η mark 100% CO2 after half curing 4kg/c
Leave it at m' for 5 hours.

(I.) Repeated Drying and Immersion Test 60'C Drying in air (standing) for 2 days and immersion in 20°C water or 5% saline for 2 days is one cycle, and this is repeated as a 1O cycle.

(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 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).

Mortar used in the invention of the present application under any conditions (sample numbers (+02) to (+09), (202)
~(209), (302)~(3H)) are samples (101) and (201) without addition of polymer dispersion.
) and (301)), the values are the same or lower, and are excellent in quality.

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

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

(c) Weight change rate Table 4 shows the results of weight change rate (%) 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, and - indicates that no cracks occurred.

All of the mortars used in the present invention are crack-free on average and have excellent 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 O symbol indicates that the material was not neutralized, the Δ symbol indicates that it was partially neutralized, and the X symbol indicates that it was 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 in that the rusted area of the reinforcing bars is 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 composition [cement: aggregate (1)
, 2 mm or less): Vinyl fiber: 5BR-A latex (solid content 2365%) = 30Nia 0:0.5:16] was poured into a mold having an uneven bottom surface, and left at room temperature for 3 hours.
Steam curing for 3 hours, natural curing for 6 days, drawing (cross section)
90cm x 180cm x 1.2 with soles 2 on the back and notches 3 (joints) around the front as shown in
A cm-sized formwork was manufactured in the factory.

This formwork was used in place of conventional formwork when pouring concrete on site, integrating the formwork and concrete. The joints formed by the joints of the formwork were filled with mortar having the same composition as the formwork. One week after filling the joints with mortar, JIS A 6910 multi-layer pattern spray material C was sprayed over the entire surface of the exterior wall for decoration.

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

As described in [2] above, according to the formwork for concrete finishing according to the present invention, a covering layer of mortar containing a polymer dispersion with good weather resistance is applied to the surface of the concrete at the same time as the construction of the main body. It is extremely easy to install as there is no need to remove the formwork, and even when reinforcing bars are placed inside the concrete, the reinforcing bars are reliably protected by the formwork and are not exposed. This has the effect of making it possible to obtain a concrete structure with extremely high durability.

Table 2: Depth of carbonation (test (mm) (3) After repeated drying (c)), after carbonization treatment - immersion in water Table 3: Water absorption - 1 (ωO

[Brief explanation of drawings]

14 is a cross-sectional view of molds J and lz made of polymer cement mortar M1 composition. ]...Formwork, 2...Soles, 3...! ; IJ missing (joint).

Claims (1)

[Claims] +j> A formwork for fixing a concrete surface, characterized by being molded with mortar containing a polymer dispersion. -2) The formwork for finishing a concrete surface according to claim 0, wherein the polymer dispersion is an anionically polymerized styrene butadiene rubber dispersion (SBR-A).