KR20020076726A - composition and manufacturing method of underwater non segregation high strength concrete - Google Patents

Abstract

PURPOSE: Provided is a high strength antiwashout underwater concrete composition which has no separation of materials, workability, good viscosity by using antiwashout underwater admixture and fluidifying agent. CONSTITUTION: The antiwashout underwater concrete composition comprises 410-470kg/m¬3 of cement, 45-55kg/m¬3 of fly ash, 220kg/m¬3 of water 600-650kg/m¬3 of fine aggregate, 900-950kg/m¬3 of coarse aggregate such as 19 or 25mm-sized gravel, 10-12kg/m¬3 of water reducing agent, melamine-based fluidifying agent, and 4-5kg/m¬3 of antiwashout underwater admixture, cellulose ether-based thickener. The antiwashout underwater concrete is prepared by dry-mixing cement, coarse and fine aggregates, and fly ash for 30sec, adding water and water reducing agent and mixing for 1 min, and adding antiwashout underwater admixture and fluidifying agent for 2.5min.

Description

Composition and manufacturing method of underwater non-separation high strength concrete

The present invention relates to a high strength concrete for underwater fire separation, and more particularly, because the separation of materials does not occur even when concrete is poured in water using an underwater fire separation admixture, thereby improving the reliability of concrete quality and preventing contamination of the construction area. Furthermore, the present invention relates to an underwater separation high strength concrete composition for preserving the construction environment and a method of manufacturing the same.

Currently, underwater concrete, which is used in civil engineering structures such as oceans, rivers, and harbors, has been developed to prevent the separation of materials in water by preventing contact between concrete and water by improving construction equipment.

In other words, measures have been taken to prevent the separation of materials in terms of construction methods, such as using a trem tube or an opening box or a method such as pumping by pump when underwater concrete is placed. However, most of these methods have a tendency to degrade concrete quality and contaminate the construction water, such as cement paste or mortar is washed out in water when the concrete is poured underwater.

Therefore, when placing concrete in water, it is possible to form a dense concrete structure without causing any separation of materials and excellent fluidity without any additional compaction. Underwater separation high strength concrete that does not contaminate the construction area by cement paste is required. do.

In order to meet these demands, the present invention increases the viscosity of the concrete by using a water-incomparable admixture, so that the separation of materials does not occur even if the concrete is placed in water, improving the reliability of the concrete quality, It is an object of the present invention to provide a high strength concrete composition and a method for producing the same, which prevents contamination and further preserves the construction environment.

More specifically, it is an object of the present invention to provide a non- underwater separation high strength concrete composition having a strength of 210 ~ 400㎏ / ㎠ most commonly used in underwater concrete structures and a method of manufacturing the same.

Underwater fire-resistant high-strength concrete composition of the present invention that achieves this object is composed of cement, coarse aggregate, fine aggregate, underwater fire separation admixture, flow admixture, fly ash, and water and water reducing agent, each unit amount (㎏ / ㎥) In other words, cement 410 ~ 470, fly ash 45 ~ 55, water 220, fine aggregate 600 ~ 650, coarse aggregate 900 ~ 950, water reducing agent 10 ~ 12, underwater fire separation admixture 4 ~ 5 It is done.

Here, cement is used five types of sulfate resistant. The physical properties and chemical composition of this cement are shown in Tables 1 and 2.

Table 1. Physical Properties of Cement

Cement type importance Powder level (㎠ / g) Stability (%) Setting time (minutes) Compressive strength (㎏ / ㎠) First closing 3 days 7 days 28 days 5 types 3.10 3200 0.1 280 390 200 270 380

Table 2. Chemical Properties of Cement

Cement type MgO (%) SO ₃ (%) Thermal loss (%) C ₃ A (%) 5 types 3.4 2.0 1.3 3.8

Coarse aggregates usually use crushed stone, which is used for concrete. For concrete formulations with a compressive strength of 210 kg / cm 2, the largest dimension is 25 mm. Property test results of such coarse aggregates are shown in Table 3.

Table 3. Property test results of coarse aggregate

Kinds Dimension (mm) importance Absorption rate (%) Assembly rate Wear rate Unit weight (㎏ / ㎥) Remarks broken stone 19 2.68 1.21 6.78 22 1698 broken stone 25 2.68 1.21 7.00 21 1708

Fine aggregates are free of chloride and use steel sand with an assembly rate of about 2.92. Because underwater unsepared concrete forms reinforced concrete structures under the surface of the ocean, ports, and rivers, the durability of the structures is reduced when chlorides or seawater are introduced. Physical properties of the fine aggregates are shown in Table 4.

Table 4. Property test results of fine aggregate

Kinds importance Absorption rate (%) Assembly rate (%) Unit weight (㎏ / ㎥) Remarks River sand 2.62 1.45 2.92 1648

Separation of water-insoluble admixtures uses cellulose ether-based thickeners. This underwater segregation admixture is essential for the formulation of underwater segregation concrete because it enhances the viscosity of the concrete and has the effect of resistance to material separation caused by the water washing action, reliability of quality, and prevention of contamination of the construction area. The properties of this HF admixture are shown in Table 5.

Table 5. Properties of Underwater Separation Admixtures

Product Name Manufacturer Exterior chief ingredient Usage (㎏ / ㎥) PHOENIX-W-A Jinwoong Chemical White powder Cellulose ether system (HPMC) 4.6

The fluid admixture uses a melamine system. It is also essential to ensure high fluidity in the waterless segregated concrete with high viscosity due to the thickening effect of the waterless segregated admixture. The components of this fluid admixture are shown in Table 6.

Table 6. Components of Fluid Admixtures

Product Name Manufacturer Exterior chief ingredient Solids concentration PH importance usage PHOENIX-W-A Jinwoong Chemical Hazel Melamine 35 7.5 1.3 22% of cement

In addition, fly ash reacts with calcium ions (Ca ⁺² ) generated by cement hydration and SiO ₃ or Al ₂ O ₃ eluted from fly ash to produce a calcium silicate hydrate (CSH) or a calcium sulfaluminate hydrate (CAH). And solidify over a long period of time to develop strength. The fly ash uses anthracite fly ash of Seocheon thermal power plant with a wet density of 0.25 and a thermal loss of 2.0. The chemical composition of this fly ash is shown in Table 7.

Table 7. Chemical Composition of Fly Ash (%)

SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO Na ₂ O K ₂ O SO ₂ Etc 55.5 33.2 4.1 0.2 1.1 0.3 4.5 0.3 0.8

In addition, the method of manufacturing a fire-resistant segregated high-strength concrete of the present invention is a process of putting cement, coarse aggregate, fine aggregate, and fly ash into a blender for 30 seconds, and mixing it for 1 minute by adding water and a water reducing agent, and mixing with water. And a flow admixture is added to the process for beaming for a total of 4 minutes.

Here, the underwater fire-resistant high-strength concrete improves the viscosity of the concrete, that is, the resistance of material separation by using the water-fired admixture, so that it has uniformity and strength of quality even in the construction of underwater dropping, and the material is separated because it uses a high flow fluid admixture. It is possible to use the general underwater concrete construction equipment in the water by compacting the horizontally distributed filling by self weight without any.

Advantages and advantages of the present invention will be readily understood by the following description of the preferred embodiments.

(First embodiment)

The mixing ratio of each material for producing the above-mentioned water-insoluble concrete is shown in Table 8.

Table 8. Mixing ratio of underwater unsepared concrete of Example 1

Coarse aggregate (mm) Unit weight (㎏ / ㎥) Sulphate Resistant Cement Fly ash water Fine aggregate (sand) Coarse aggregate (gravel) Water reducing agent Underwater fire separation admixture 25 mm 412 46 220 647 920 10.1 4.6

Mix each material in the mixing ratio as shown in Table 8 to prepare the water-insoluble concrete. The manufacturing method is largely composed of three steps.

First, a dry beam is performed in a first step. That is, cement, gravel, sand, fly ash is put into the blender in the same ratio as described above and subjected to dry beam for 30 seconds.

The second step is a step of mixing by adding water and a water reducing agent. This process lasts for 1 minute.

The third step is a process of adding and mixing the water-in-separation admixture and the fluid admixture and beaming them. This process is carried out for a total of 4 minutes in addition to the time of the first and second processes.

The raw concrete obtained by such a process was prepared in 10 mm x 20 cm mold using a mold in accordance with KSF2405, and the mold was placed in a water tank at a height of 10 cm under water in a water bath. After keeping constant, the concrete is divided into 5 equal parts of the volume and filled freely.

After about 10 minutes, the mold is taken out of the water and stored in a constant temperature and humidity room for 24 hours in order to prevent evaporation of water. Then, the mold is demolded and cured under water at 20 ± 3 ℃. The compressive strength of this specimen is shown in Table 9.

Table 9. Compressive Strength of the First Example (kg / cm 2)

Classification Retirement Date 7 days 28 days Underwater production specimen 173 248 Lifting specimen 196 269

(Second embodiment)

Table 10. Mixing ratio of undissolved concrete of Example 2

Coarse aggregate (mm) Unit weight (㎏ / ㎥) Sulphate Resistant Cement Fly ash water Fine aggregate (sand) Coarse aggregate (gravel) Water reducing agent Underwater fire separation admixture 25 mm 461 51 220 613 909 11.3 4.6

Since the concrete is prepared by the same production method as in the first embodiment by mixing each material at the above-described mixing ratio, specific description is omitted and only the compressive strength thereof is shown in Table 11.

Table 11. Compressive Strength of the Second Example (kg / cm 2)

Classification Retirement Date 7 days 28 days Underwater production specimen 235 353 Lifting specimen 262 376

As described above, the present invention can increase the viscosity of the concrete while maintaining the required workability by using a water-incombustible admixture and a fluidizing agent, thereby improving the reliability of the concrete quality, thereby improving the construction quality and construction. It can be effective in preventing pollution and preserving the environment.

Claims (8)

Consisting of cement, coarse aggregate, fine aggregate, in-water admixture, fluid admixture, fly ash, and water and water reducing agent, Cement 410 ~ 470, Fly Ash 45 ~ 55, Water Aggregate 220 ~ 600, Fine Aggregate 600 ~ 650, Coarse Aggregate 900 ~ 950, Water Repellent 10 ~ 12, Underwater Fire Separation Underwater separation high strength concrete composition, characterized in that the admixture is 4-5. The method of claim 1, wherein the cement is in-water separation high strength concrete composition, characterized in that five. The high strength concrete composition of claim 1, wherein the coarse aggregate is crushed stone of 25 mm and 19 mm. The method of claim 1, wherein the fine aggregate is in-sea segregation high strength concrete composition, characterized in that the granulation rate of about 2.92. The in-separable high strength concrete composition of claim 1, wherein the in-separable admixture is a cellulose ether-based thickener. The method of claim 1, wherein the flow admixture is melamine-based high strength concrete composition in water. The high strength concrete composition of claim 1, wherein the fly ash is anthracite fly ash. Cement, coarse aggregate, fine aggregate, fly ash into a blender for 30 seconds Mixing the water and water reducing agent for 1 minute, Underwater separation high strength concrete manufacturing method consisting of a step of mixing the water admixture admixtures and fluid admixtures and beaming for a total of 4 minutes.