JP2618366B2 - Method for producing hydraulically cured product - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a hydraulically cured product, and more particularly, to a method for applying mechanical strength to a member having a complicated shape, and a method for producing a high-strength material. The present invention relates to a method for producing a hydraulically hardened body applicable to the production of concrete requiring high fluidity.

[Conventional technology]

Mixing silica fume with cement to obtain high-strength mortar or concrete is a conventional technique. However, since silica fume is an ultrafine powder having a very large specific surface area, a relatively large amount of water is required for kneading, and as a result, a sufficiently high strength has not been achieved.

In recent years, a technique has been developed in which a large amount of a high-performance water reducing agent is added to cement mixed with silica fume and kneading is performed for a relatively long time to knead the paste with a very small amount of water. (For example,
-59182 specification).

[Problems to be solved by the invention]

However, the paste obtained by this method also has a high yield value and poor fluidity, and when used as concrete, has a small slump and poor workability. On the other hand, the concrete containing silica fume which has been practically used conventionally has a water binding ratio of 25%.
%, The unit guess was 130 kg / cm ³ or more, and a large amount of water was used, and a sufficient strength improving effect was not obtained.

[Means for solving the problem]

As a result of intensive research to solve this problem, by mixing powder having an intermediate particle size with powder mixed with cement silica fume, the fluidity of the paste is significantly improved at a specific compounding ratio, The present inventors have found that even when used as concrete, a slump having good workability can be obtained.

That is, the present invention uses a powder C having a specific surface area of 2000~4000cm ² / g of cement A and a specific surface area 100000~300000cm ² / g of silica fume B and both intermediate specific surface 6000~30000cm ² / g 30% to 80% by weight of powder A and 5 to 20% of powder B
% By weight, powder C having a composition in the range of 10 to 50% by weight, a high-performance water reducing agent of 2.5 to 4% by weight of the mixed powder and 1
This is a method for producing a hydraulically hardened body, characterized by adding 3 to 20% of water, kneading and curing.

(A) Cement Cement A of the present invention has a specific surface area of 2000 to 4000 cm ² /
g. Portland cement according to ordinary JIS standards has a specific surface area in this range.

The cement A referred to in the present invention includes, in addition to such Portland cement, cements used in the same manner as Portland cement in various cements such as alumina cement, silica cement, fly ash cement, blast furnace cement and the like.

(B) Silica Fume B Silica fume B used in the present invention is amorphous ultrafine particles of SiO _{2 which} are by-produced during ferrosilicon production, and most of them have a pozzolanic reactivity and a particle diameter of 1 μm or less. The specific surface area is in the range of 100,000 to 300,000 cm ² / g.

(C) Powder C In the present invention, the powder C (intermediate particle size powder) having an intermediate particle size between the cement A and the silica fume B is a powder having a specific surface area in the range of 6,000 to 30,000 cm ² / g. The material is not particularly limited, but examples thereof include blast furnace slag, silica stone, diatomaceous earth, limestone, fly ash, and the like, which are obtained by pulverizing these with an appropriate pulverizer and then classifying them with an air separator.

(D) High-performance water reducer A high-performance water reducer is a surfactant used to obtain a high-strength concrete by drastically lowering the water-cement ratio, and is also used as a fluidizer for hardened concrete. Agents, for example, naphthalenesulfonic acid formaldehyde condensate salt, naphthalenesulfonic acid-modified lignin condensate, highly condensed triazine-based compound, sulfonated melamine condensate, etc., and these are commercially available as high performance water reducing agents under various trade names Have been.

Mixing Ratio In the production of the hydraulically cured product of the present invention, the mixing ratio is important together with the range of the specific surface area of each powder component.
That is, a mixed powder having a composition of powder A: 30 to 80% by weight, powder B: 5 to 20% by weight, and powder C: 10 to 50% by weight is used.

Further, a high-performance water reducing agent is indispensable for sufficient dispersion of the powder, and its addition ratio is suitably 2.5 to 4%. If it is less than 2.5%, a sufficient dispersing effect cannot be obtained, and if it exceeds 4%, no further water reducing effect can be obtained, and it is economically meaningless.

It is appropriate that the amount of water to be added is 13 to 20% based on the weight of the powder. If the amount is less than the above range, kneading is not possible.

[Action]

In the conventional method, particularly in the method described in Japanese Patent Application No. 60-59182, the space between cement particles is filled with silica fume having a particle diameter of several hundredths of cement particles and water,
The paste is made to flow, but since water as a fluid component is used to fill in the space between the silica fume particles, the flowability of the paste becomes poor with a small amount of water.

The method of the present invention is intended to fill the spaces between cement particles with particles smaller than the cement particles and to fill the gaps with silica fume and water.

According to this method, if the amount of water is the same as that of the paste, the fluidity of the paste according to the present invention is improved, and if the amount of water is the same as that of the paste, kneading is possible with a smaller amount of water. Body strength is improved.

〔Example〕

Hereinafter, the present invention will be described with reference to examples, but these do not limit the present invention.

Examples 1-3, Comparative Examples 1-5 Ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.
Specific surface area of 3300 cm ² / g), silica fume (manufactured by Elchem, specific surface area of 200,000 cm ² / g) and silica fine powder having the specific surface area shown in Table 1 are mixed at the mixing ratio shown in the table, and a high performance water reducing agent ( The flow of a fresh paste obtained by adding 3% to the powder weight and 16% of water with Mighty 150, naphthalenesulfonic acid formaldehyde high-condensation product manufactured by Kao Corporation, and kneading with an omni mixer for 5 minutes. Value and 5cm
Table 1 shows the test results of the compressive strength of the test specimens which were formed into a φ × 10 cm and cured in water at 20 ° C. for one week.

Examples 4-6 and Comparative Examples 6-10 Ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.
Specific surface area of 3300 cm ² / g), silica fume (manufactured by Elchem, specific surface area of 200,000 cm ² / g) and silica fine powder having the specific surface area shown in Table 1 are mixed together in the unit amount shown in the table, and a high performance water reducing agent ( 3% of the powder weight and 17% of water were added to the powder paste, and the mixture was kneaded for 5 minutes with an omni mixer. Charge the same volume, knead for 1 minute and obtain the mortar flow value, 5cmφ × 10c
Table 2 shows the test results of the compressive strength of the test pieces which were molded in m and cured in water at 20 ° C. for one week.

Examples 7-9 and Comparative Examples 11-15 Ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.
Blast furnace slag powder having a specific surface area of 3300 cm ² / g), silica fume (manufactured by Elchem, specific surface area of 200,000 cm ² / g), and a specific surface area shown in Table 3 are mixed in the unit amount shown in the table, and a high performance water reducing agent (Kao Co., Ltd., Mighty 150) was added to a fresh paste obtained by adding 3% to the powder weight and 17% of water and kneading with an omni mixer for 5 minutes to obtain a crude paste having a unit amount shown in Table 3 Aggregate (crushed stone from Ome) and fine aggregate were charged, and the slump of the obtained fresh concrete was measured. Then, it was molded into 10cmφ × 20cm and cured at 20 ° C for 28 days in water. It is shown in Table 3.

[Effects of the Invention] In the method of the present invention, the space between cement particles is filled with particles of intermediate particle size smaller than cement particles and larger than silica fume, and the gaps are filled with silica fume and water. And the slump value in the case of concrete increases, and handling during concrete placement becomes extremely easy. Further, since particles larger than silica fume are filled, the effect of reducing the amount of expensive silica fume can be obtained, and kneading can be performed with a smaller amount of water than in the case of using silica fume alone, and the strength of the cured product is improved.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C04B 18:14 14:02)

Claims (1)

(57) [Claims] [Claim 1] with a powder C having a specific surface area of 2000~4000cm ² / g of cement A and a specific surface area 100000~300000cm ² / g of silica fume B and both intermediate specific surface 6000~30000cm ² / g, 30-80% by weight of cement A, 5 of silica fume B
To a mixed powder having a composition of about 20% by weight and a powder C in the range of 10% to 50% by weight, a high performance water reducing agent of 2.5 to 4% of the mixed powder weight and water of 13 to 20% are added. A method for producing a hydraulically cured product, comprising kneading and curing.