KR100196702B1 - Method for preparing concrete - Google Patents

Abstract

[purpose]

Provides high quality, high durability concrete

[Configuration]

The mixing ratio of high durability concrete is based on water-cement ratio 43% (water 164kg / ㎥) and fine aggregate rate 45% (grain aggregate 850kg / ㎥, coarse aggregate 1040kg / ㎥). That is, cement 285kg / ㎥-342kg / ㎥, water aggregate 164kg / ㎥, fine aggregate 850kg / ㎥, fly ash 57kg / ㎥ or silica fume 38kg / ㎥ or blast furnace slag 47.5kg / ㎥ and coarse aggregate 1040kg / ㎥ A high quality concrete is produced by blending the air entrainer at 0.04% and the high lubricant at 1.2% 01.8%.

Description

High durability concrete manufacturing method for high quality construction

1 is an explanatory diagram of a chlorine ion permeation device,

2 is a scene of rebar corrosion test,

3 is a sulphate test scene diagram,

4 is a freeze thaw test scene,

5 is a panoramic view of the Tetrapod test site at Dangjin Thermal Power Plant.

6 is a scene of mounting the specimen shore for measuring long-term behavior,

7 is a concrete Raamen bridge construction scene in the Uiwang ICD site,

8 is the construction of the Gayang sewage treatment barriers,

9 is a panoramic view of Gayang Sewage Treatment Plant.

The present invention relates to a manufacturing method of high durability concrete, and more particularly to a manufacturing method of high durability concrete for high-quality construction.

Conventional concrete was known to satisfy the construction only if the compressive strength is satisfied. However, due to environmental factors, the concrete corrodes over time and the reinforcing steel in the concrete corrodes, which significantly reduces the performance of the reinforced concrete structure. Therefore, the required life span of the structure is not reached, and in some cases, frequent renovation or early reconstruction of the structure results in enormous national economic losses.

The present invention is easy to mix and manufacture concrete in order to achieve high-quality concrete construction, the purpose is to improve the ease of field work and the excellent quality of the concrete produced. In order to achieve this purpose, the workability (slump 18 ± 3cm) is increased compared to the existing concrete to facilitate the job, accordingly anomalous addition of water for convenience of work in the conventional site to reduce the strength and performance of the concrete Eliminates the causes of poor construction and maximizes resistance to environmental factors (salt, freeze-thawing, rebar corrosion, etc.) to maintain satisfactory reliability and serviceability during the life of the structure. To help. And the mixing ratio was decided to derive the design mix strength by fully considering the errors (type of aggregate, aggregate surface number, etc.) generated during concrete production.

In order to achieve the above object, the high durability concrete compounding ratio in the present invention uses fly ash, blast furnace slag, and silica fume, which are industrial by-products, to replace the cement. Not only has it improved significantly, but it has also helped to preserve the environment.

The cement used in the embodiment of the present invention is a first-class ordinary portland cement of domestic S company, and the test results on the basic physical properties are shown in the following table, which satisfies the KS regulations.

Aggregates for concrete are clean, hard, durable, of moderate particle size, and chemically stable, and are collected from streams near Seoul that contain no thin, slender stone, clay, or organic impurities or harmful substances. Fine aggregates were used, and the specific aggregate used was 2.60 and had an absorption rate of 1.5%.

In addition, the coarse aggregate used in the embodiment of the present invention, like aggregates used in general concrete, has better physical properties than coarse grindstones, and it is better to use coarse aggregates having an appropriate maximum dimension and particle size distribution, but recently, it is difficult to obtain the coarse stones. At this time, the maximum aggregate size is 25mm crushed stone was used. The specific gravity used was 2.75 and the absorption was 1.0%.

In the embodiment of the present invention, as the main variable, a mixed material (fly ash, blast furnace slag, silica fume) was used. The fly ash was manufactured by H company as Boryeong acid, and the used blast furnace slag was produced at Gwangyang Works. The surface area was 4000 cm 2 / g as measured by the Blaine permeation method, and silica fume was used by Norwegian E company. In addition, the high fluidizing agent used in the present embodiment is a high fluidizing agent which is a copolymer suitable to ASTM C494 type D and G manufactured by Mighty Co., Ltd. in Korea.

The distinction of admixtures is in accordance with the following ASTM C494. The specific fluidization agent used had a specific gravity of 1.20 ± 0.01, a solid content of 41 ± 1%, a color of dark brown color, a pH of 8-10, and no chloride of 0.00%. The high fluidizing agent used in the embodiment of the present invention was able to reduce the amount of water by 20-30% when concrete mixing by securing the fluidity of the cement particles, and the material than the concrete without the high fluidizing agent under the same water-cement ratio conditions Workability is excellent without separation and fluidity lasts for a considerable time to facilitate pouring work.

Air entrainers were used to properly entrain fine air bubbles in concrete. Air entrainment significantly improves the durability of concrete when exposed to moisture and freeze-thawing, and improves the workability of non-solid concrete. Airborne concrete contains fine air bubbles evenly distributed throughout the cement pool. The air entraining agent used in the embodiment of the present invention is a water-soluble solution that satisfies the above requirements under the trade name EZAiR of K Co., Ltd. in Korea, and does not contain chloride.

Meanwhile, in the present invention, the mixing ratio of the high durability concrete is 350 kg / cm 2 or more in strength, and the amount of the air entraining agent and the amount of the high oil emulsifier is determined for each example in order to maintain the fluidity of slump 18 ± 3 cm and to secure an appropriate amount of air. It is. The maximum size of the coarse aggregate was 25mm in consideration of economic efficiency, and fly ash, blast furnace slag and silica fume were used as cement admixtures as admixtures to increase the durability of concrete.

In addition, a total of 11 compounding ratios (Table 2) were determined based on the cement binder content 380kg / ㎥, water-cement ratio 43%, and fine aggregate 45%, and the appropriate blending ratio was recommended according to the importance and external environmental factors of the structure.

The following is an example of the external environmental impact (freeze thaw, rebar corrosion, sulfate salt, etc.).

Example 1

323kg / ㎥ of cement, flyash 57kg / ㎥ as admixture, water 164kg / ㎥, fine aggregate 850kg / ㎥, maximum size 25mm coarse aggregate 1040kg / ㎥, air entrainer 0.04%, high fluidizing agent 1.5% . The permeability of the test specimen was 565 (Coulomb), which was much lower than the standard value of 510, resulting in excellent resistance to permeability, 270kg / ㎡ on the 7th day, and 433kg / ㎡ on the 28th day. , Splitting strength was 48 kg / cm 2 at 28 days, and flexural strength was 48 kg / cm 2.

Example 2

Water and fine aggregate, coarse aggregate, and air entrainer are the same as in Example 1, cement 266kg / ㎥, fly ash 114kg / ㎥, and formulated with 1.2% high fluidizing agent and measured by the items and indicated below.

Example 3

Water, fine aggregate, coarse aggregate, and air entrainer were the same as in Example 1, and the specimens were prepared by mixing 323 kg / m 3 of cement, 57 kg / m 3 of fly ash, and 1.3% of a high softening agent, respectively, and measured. The measurements are listed separately by category.

Example 4

Water and fine aggregate, coarse aggregate and air entrainer were the same as in Example 1, cement 342kg / ㎥, admixture with silica fume 38kg / ㎥, high fluidizing agent 1.4% was made to measure the specimens. The measurements are listed below by category.

Example 5

Water and fine aggregate, coarse aggregate, and air entrainer were the same as in Example 1, cement 342kg / ㎥, silica fume 38kg / ㎥, high-purifying agent 1.5% and the specimens were made and measured respectively. The measurement results are shown below by item.

Example 6

Water and fine aggregate, coarse aggregate and known entraining agent were the same as in Example 1, cement 332.5kg / ㎥, blast furnace slag 47.5kg / ㎥, high fluidizing agent 1.8% and the specimens were made and measured respectively.

The measurement results are shown below by item.

Example 7

Water and fine aggregate, coarse aggregate, and air entrainer were the same as in Example 1, and the specimens were prepared by mixing at a ratio of cement of 285 kg / m 3, blast furnace slag 95 kg / m 3, and a high fluidizing agent of 1.7%. The measurement results are shown below by item.

Example 8

Water and fine aggregate, coarse aggregate, and air entrainer were the same as in Example 1, and the specimen was prepared by mixing at a ratio of cement of 285 kg / m 3, fly ash 57 kg / m 3, silica fume 38 kg / m 3, and a high fluidizing agent of 1.6%. The measurement results are shown below by item.

Example 9

Water and fine aggregate, coarse aggregate, and air entrainer were the same as in Example 1, the specimen was prepared by mixing in a ratio of cement 323kg / ㎥, fly ash 57kg / ㎥, high fluidizing agent 1.4% and measured. The measurement results are shown below by item.

Example 10

Water and fine aggregate, coarse aggregate, and air entrainer were the same as in Example 1, cemented 285kg / ㎥, fly ash 57kg / ㎥, silica fume 38kg / ㎥, high fluidizing agent 1.5% ratio was made to measure the specimen. The measurement results are shown below by item.

Durability enhancement experiments for each of the examples were performed as follows to demonstrate the performance.

1) Freeze thaw resistance test

KS F 2456 (Quick Freeze) is a test that periodically applies the temperature below freezing point (18 degrees below freezing point) and the temperature above freezing point (4 degrees below image) in concrete specimens. Test method of resistance of concrete to melting) was carried out according to the standard test method (Table 3). The damage of the freeze-thawing test is determined by measuring the dynamic elastic modulus at regular intervals. In principle, 300 cycles are used. If the relative dynamic modulus is less than 60%, the experiment is terminated.

2) Permeability test

In the water permeability test (FIG. 1), concrete causes various deterioration through small pores. Therefore, the smaller the permeability, the more resistant the concrete is to corrosion. In the permeability test of this embodiment, the permeability was excellent enough to not measure the permeability (Table 4), and the permeability was only measured through the chlorine ion permeation test.

3) corrosion resistance test

Corrosion resistance test measures the current flowing in the DC circuit of each of the embodiments. As the corrosion of the reinforcing steel in the concrete progresses, the current is rapidly increased due to the crack due to the volume expansion of the steel (Figure 2). In addition, when the current gradually increases, it is based on the experiment until the amount of current reaches 20 mA (Table 5).

4) Sulfate Resistance Test

In the sulfate resistance test of the embodiment of the present invention, the concrete is chemically reacted by sulfuric acid contained in the ground, in water or in the atmosphere. This chemical reaction causes the concrete to expand and crack. In the embodiment of the present invention, the specimen was precipitated in the sulfate solution (FIG. 3) and compared with the results of general concrete, and the resistance thereof was significantly increased (Table 6). It was confirmed that the concrete. In general, five kinds of cement products (sulfuric acid cement) are used, but considering that the cement is quite expensive, the durable concrete of the present invention has proved to be quite effective in terms of economy.

In addition, in the high flowability, it was confirmed that the workability was significantly improved by maintaining the high flowability of the slump 21 ± 2Cm after mixing as described above, and the slump 18 ± 3Cm just before pouring after 30 minutes, and securing fluidity after 1 hour. It can be maintained by splitting.

5) strength characteristics

The following Table 7 shows the experimental measurements of the strength characteristics of the concrete structure by the combination of each embodiment. In particular, the examples of Examples 4 and 5 are superior to those using fly ash or blast furnace slag, based on the design strength of 500 kg / cm 2. However, since silica fume is an imported product, there is a problem in that the manufacturing cost is high, but it is absolutely necessary for structures of high importance or long life, such as a radioactive waste storage or a required life of more than 300 years.

And the embodiment of each variable of the embodiment of the present invention is a regional difference, for example, the difference in temperature, such as the central north north region and mountainous region or bridge (PC, long bridge, general bridge), as well as concrete dam, box structure (subway, Waterways, underground passages), sewage treatment plants, radioactive waste sites, chemical reservoirs, tunnels, port facilities, nuclear power plants and building structures.

6) On-site casting test

For practical application of high-durability concrete, the compounding ratio obtained through the durability test was verified by placing the practical application in various places as shown in Table 8 (see Fig. 5-9).

As described above, according to the present invention, the compounding ratio of the high durability concrete can be optimized economically by using a high fluidizing agent and an air entrainer in addition to cement, gravel, sand, and water, and the environmental deterioration factors and structures It is possible to obtain a suitable high durability concrete according to the importance, and the strength of the high durability concrete of the present invention can express at least 350 strength or more, and when using silica fume can express more than 500 strength, and also fly ash and blast furnace slag The pozzolanic reaction is a new invention that is industrially beneficial, with 56 days stronger than 28 days of strength.

Claims (2)

In manufacturing high durability concrete, fly ash 57kg / m3, or silica fume 38kg / m3 or blast furnace slag 47.5kg / m3, cement 285kg / m3 -342kg / m3, water 164kg / m3, fine aggregate 850kg / ㎥, coarse aggregate 1040kg / ㎥ of maximum size of 25mm and air emulsifier 0.04%, high softening agent 1.2% -1.8% of the high durability concrete manufacturing method for high-quality construction, characterized in that the composition is formulated. According to claim 1, Cement 285kg / ㎥, water 164kg / ㎥, fine aggregate 850kg / ㎥, coarse aggregate 1040kg / ㎥ of 25mm maximum dimension, air emulsifier 0.04%, fly ash 57kg / ㎥ in high fluidizing agent 1.6%, Highly durable concrete manufacturing method for high-quality construction, characterized in that the addition of silica fume 38kg / ㎥ added to each other.