KR19990049245A - Manufacturing method of high strength cement with high fluidity and low heat - Google Patents

Abstract

The present invention is to provide a method for producing a high strength cement having fluidity and low thermal properties by changing the clinker mineral composition and cement particle size characteristics.

Conventional concrete products using high-strength cement and high-strength admixtures have good strength characteristics, but workability is reduced due to fluidity deterioration, and there is a disadvantage that pimples are easily generated on the surface of concrete products due to poor molding.

The cement of the present invention can not only solve the workability problems that occur in the existing cement, but also the concrete products and structures made of the cement of the present invention have excellent workability, improved durability and less cracking due to high strength and low heat characteristics. In addition, surface finish characteristics and chemical resistance properties have been greatly improved.

Description

Manufacturing method of high strength cement having high fluidity and low heat

The present invention relates to a method for producing high strength cement having high fluidity and low heat characteristics.

In general, concrete, which is widely used as a construction material, is gradually increasing in strength due to the diversification and enhancement of structures, and requires low heat characteristics due to massification with high fluidity during work. In particular, in the case of pretension type centrifugal concrete piles, which are secondary concrete products, high strength of more than 800kg _f / ㎠ of concrete compressive strength is required for practical use. One of the methods of manufacturing pretensioned centrifugal concrete piles to meet these demands, using a special cement or gypsum-based high-strength admixture with ordinary gypsum-based additives in Portland cement, compressive strength 800kg _f without steam curing facilities without autoclave curing facilities. High strength products of more than / cm 2 were prepared.

However, conventional concrete products using high-strength cement or high-strength admixtures have excellent strength characteristics but have poor workability due to low fluidity due to low cement water ratio (W / C ratio) and strict management or application standards due to poor molding when compacted. This is necessary, in particular, if the work standards are not adhered to, there is a disadvantage that tends to occur on the concrete product surface.

Here, the reason why the concrete applied by the above technique is inferior in workability is the rapid drop in fluidity of the highly fluid concrete which is closely related to the concrete workability and the calcium-aluminate having the fastest hydration rate among cement minerals (3CaO · Al ₂ O ₃ ). And gypsum are the early cement hydration catalysts that produce ethrinite (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) minerals by rapid hydration reaction.

Here, high-strength cement or high-strength admixtures exhibit high strength by adopting a high-strength mechanism using calcium-aluminate and gypsum that produce high ethrinite minerals during the hydration process and using a large amount of high-molecular fires. It is pointed out that the loss of productivity due to the loss of fluidity of concrete at the early stage, resulting in low productivity.

The present invention not only solves the problem of deterioration in workability caused by ethrinzite mineral transition due to rapid hydration by limiting calcium aluminate mineral component which loses initial fluidity by rapidly reacting with water and hydrating in cement mineral. Compared with high strength admixtures, the powder degree is similar, but the particle size distribution characteristics are properly controlled to provide a method for producing high strength cements having high fluidity and low heat characteristics, which are significantly improved in flow and viscosity characteristics of cement pastes compared to existing technologies. There is this.

The present invention is a method for producing a high-strength cement having fluidity and low heat characteristics by changing the cement mineral composition and particle size characteristics, which is different from the high-strength cement or high-strength admixture in the form of mixed cement using organic additives or other additives It is a high flow, low heat, high strength cement with high flowability, high strength mechanism, and it can solve the problems of workability caused by mixing and compaction as well as the problems of grinds occurring on the surface of concrete secondary products with compressive strength of 800kg _f / ㎠ or more. It is a high performance, high strength cement that can also be used as a high durability, high strength grout material for large structures.

Cement is a mineral-based hydraulic material made of limestone, clay, and iron raw materials by firing in a kiln (rotary kiln) at a high temperature of about 1450 ° C. and then quenching them to prepare clinker and grinding them by adding about 3 to 5% of gypsum. Say the ingredients. Portland cement is currently divided into five types: one ordinary portland cement, two medium heat cements, three crude steel cements, four low heat cements, and five sulfate resistant cements. Among them, the five types of sulfate-resistant cements are composed of calcium-aluminate mineral content of 5% or less and allite (2CaOSiO ₂ ) mineral content of 50% or less, excellent sulfate resistance, reduced hydration heat, reduced dry shrinkage, and long-term strength. It is widely used in marine development, construction of sulphate soils and hot springs, factory wastewater facilities, and nuclear reactors.

This type of cement is a measure to control the physical properties of the cement to have the appropriate properties according to the intended use and purpose by adjusting the cement mineral composition according to the intended use.

Here, the technical concept of high strength cement having high flowability and low heat characteristics of the present invention will be described. When cement and water are mixed, it becomes a fluid cement paste at first, but gradually hardens with time, and loses fluidity. Finally, it is hardened by the hydration reaction of cement compound to express strength.

Among the cement compounds, the mineral with the highest hydration rate is calcium-aluminate, so calcium-aluminate content has the greatest effect on the curing of the initial cement paste. It is natural that the lower the calcium-aluminate content in the cement, the slower the curing rate and the fluidity of the paste is maintained.

However, such measures alone are difficult to achieve the high-flow low heat generation characteristics currently required by the construction industry. Therefore, the cement of the present invention is to control the calcium-aluminate content of the clinker mineral, the gypsum and cement particle size distribution used to invent a high-performance high-strength cement having high flow, low heat generation, chemical resistance, seawater resistance properties. Factors affecting the hydration rate and fluidity of cement are cement particle size characteristics in addition to mineral composition. As the powder level increases, that is, the finer the particles, the larger the specific surface area of the cement in contact with water, the faster the hydration rate, the faster curing, and the faster the paste fluidity.

However, in order to exhibit high strength properties, it is essential to secure the high strength properties by increasing the specific surface area, which results in poor fluidity. In the case of cement particle size characteristics, even if the average particle diameter is the same, very fine particles, coarse particles, and medium particles are properly distributed, so that the voids of the cement powder are reduced and the filling property is improved, so that at a constant water cement ratio (W / C%) It was confirmed in the experimental or production mill mill that the cement paste fluidity can be greatly improved by increasing the thickness of the water film surrounding each particle of the cement powder. In addition, it was possible to control the heat of hydration by increasing the gypsum content.

Compared with conventional high strength cements or high strength admixtures, the high flow and low heat high strength cements of the present invention produce a large amount of ethrinite by hydration of calcium-aluminate and gypsum, resulting in high strength and high strength. It expresses high strength, high durability and low heat generation while securing significantly improved flowability of concrete.

High-strength cement having high flowability and low heat characteristics of the present invention is calcium to aluminate content of 2 to 5% by weight, bellite (2CaO · SiO ₂ ) content 25 to 40% by weight, allite (3CaO · SiO ₂ ) content a 40 to 50% by weight, calcium alumino-ferrite _{(4CaO · Al 2 O 3 ·} Fe 2 O 3) anhydrous gypsum (CaSO ₄₎ content for the unit 10 to the clinker 100 16% by weight as SO ₃ content of the reference 2 to 6 parts by weight, 2 to 15 parts by weight of slag or fly ash is added, and the powder degree is 3800 to 4500 cm 2 / g of Blaine, 44 to the residue 2 to 8%, less than 1 ㎛ 10 It is prepared by grinding to a level of 15%.

Here, in the case where anhydrous gypsum is added in an amount less than 2 parts by weight, it is difficult to give high strength because the hydration activity of the cement of the present invention is too small. When it exceeds 6 parts by weight, unreacted gypsum remains to cause a decrease in strength. Occurs.

Particularly, when the amount of 44㎛ residue is pulverized to 2% or less during pulverization, the cement powder is generally finely divided and the filling property of the powder is reduced, thereby greatly reducing the fluidity of the cement paste, thereby decreasing concrete workability. The durability and strength expression characteristics were lowered due to the increase in required amount (W / C%) during the mixing. On the other hand, when the cement powder is pulverized such that the amount of 44 μm residue is 8% or more at the level of 3800 to 4500 cm 2 / g of the lane, the flowability of cement and concrete is greatly improved, but the grinding efficiency is greatly reduced, which is undesirable. Preferably, with a powder of 3800 to 4300 cm 2 / g of the blain, to control the filling of the cement powder 44㎛ residue is controlled to 2 to 8%, 1㎛ or less to 10 to 15% with high fluidity, low heat characteristics Expressing high strength is the basic technique of the present invention.

Concrete products and structures made of such clinker mineral composition and particle size-controlled cement have excellent workability, improved durability, less cracking due to high strength and low thermal properties, and significantly improved surface finishing and chemical resistance. .

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 (Comparative Examples 1 to 5)

In Examples and Comparative Examples 1 to 4, the viscosity of the paste, the strength of the concrete, and the slump were measured using high strength cements having high flowability and low heat characteristics and conventional cements having the chemical composition and particle size characteristics of Table 1 below. Paste viscosity was added by adding 1 part by weight of a high fluidizing agent and 30 parts by weight of water to a high-strength cement 100 parts by mixing for 3 minutes and measured using a rotational viscometer. Next, the high strength cement having the properties of Table 1 was prepared under the concrete mixing conditions of Tables 2 and 3, and then the concrete strength and slump were measured.

Evaluation of concrete and paste properties results confirmed that the concrete products made of the cement of the present invention had better workability and better strength and durability than other cements.

In the following table, C ₃ A calcium-aluminate teuyigo inner ear, C ₂ S is the light level, C ₃ S is the light Al, C ₄ AF represents a calcium alumino ferrite.

Mineral composition Chemical composition Particle size C ₃ A C ₂ S C ₃ S C ₄ AF SO ₃ lg.loss Blaine 44㎛ residue Example (High Flow Low Heat Steel Cement) 3.9 32.5 39.7 12.7 4.4 0.3 4400 6.6 Comparative example 1. High strength cement 10.1 30.2 36.2 7.3 7.2 1.2 4100 2.3 2.1 class cement 11.0 33.8 37.4 9.4 2.1 1.8 3240 8.9 3.5 type cement 3.5 37.4 37.7 13.4 1.9 1.2 3200 4.0 4.Bellelite Cement 3.0 49.2 24.5 18.0 2.3 1.5 3950 2.8

Formulation condition Slump (cm) Strength (㎠ / G) Paste Viscosity (CP) C / M W / C High Dynamic Fire S / A 1 day 3 days 7 days 0 min 10 minutes 20 minutes 30 minutes Example 580 25.5 1.5 35 5.0 812 853 946 420 470 510 550 Comparative Example 1 580 25.5 1.5 35 1.0 810 850 903 1470 2680 Side payment Side payment Comparative Example 2 580 25.5 1.5 35 1.4 724 783 856 1910 2840 Side payment Side payment Comparative Example 3 580 25.5 1.5 35 3.1 711 792 888 900 1260 2540 Side payment Comparative Example 4 580 25.5 1.5 35 2.9 746 798 831 1870 2950 Side payment Side payment Comparative Example ⑤ 560 + 56 ^★ 25.5 1.65 35 2.5 802 845 908 820 1070 1140 1190

Specimen: Centrifugal Molding

Curing condition; 80 ℃ steam curing (3 hours)

Comparative Example 5; 560 (1 Type Cement) + 56 ^★ (Gypsum High Strength Admixture)

Formulation condition Slump Flow (cm) Strength (cm2 / g) # Freeze thawing (300 cycles) Insulation temperature rise (10 days) C / M W / C High Dynamic Fire S / A 3 days 7 days 28 days Example 470 30.0 1.2 45 64 × 63 611 720 894 Good 64 ℃ Comparative Example ④ 525 33.5 1.2 45 63 × 61 405 490 703 Good 65 ℃

High-strength cement having high flow and low heat properties of the present invention is a work that appears as an ethrinzite mineral transition due to rapid hydration reaction by limiting the calcium-aluminate mineral component that loses initial fluidity by rapidly reacting with water and hydrating in cement minerals. Not only solved the problem of deterioration, but also the similarity of powder compared to high-strength cement or high-strength admixture, but the particle size distribution characteristics were properly controlled, which greatly improved the flowability and viscosity characteristics of cement paste. This has the advantage of greatly increasing.

Claims (3)

Calcium-aluminate, Bell Light, Al light, hayeoseo mixed and pulverized calcium aluminosilicate of anhydrite with respect to a ferrite clinker 100 parts by weight consisting of the S0 ₃ reference to 2 to 6 parts by weight of the slag or fly ash from 2 to 15 parts by weight A method of producing high strength cement having high fluidity and low heat characteristics, characterized in that it is produced. According to claim 1, wherein the clinker mineral content is composed of 2 to 5% by weight of calcium-aluminate, 25 to 40% by weight of bellite, 40 to 50% by weight of alite, and 10 to 16% by weight of calcium alumino ferrite. Method for producing a high strength cement having high fluidity and low heat characteristics, characterized in that there is. According to claim 1, wherein the cement powder is high fluidity and low heat characterized in that the 44㎛ residue at 2 to 8%, 1㎛ or less of 10 to 15% at a level of 3800 to 4500 cm 2 / g of the blade Method for producing high strength cement having characteristics.