JPH04260644A - Hydraulic composition for highly strong concrete and production of highly strong mortar or concrete - Google Patents

Abstract

PURPOSE:To provide a hydraulic composition giving mortar or concrete having a large initial strength and a large long-term strength by employing blast furnace glassy slag fine powder having a specific particle distribution. CONSTITUTION:A hydraulic composition comprises 20-80wt.% of blast furnace glassy fine powder comprising >=90wt.% of particles passing through a sieve having a size of 10mum, 50-80wt.% of the particles passing through a sieve having a size of 5mum and 10-20wt.% of the particles passing through a sieve having a size of 1mum as shown in the oblique line region of the figure, 80-20wt.% of a cement and, if necessary, gypsum in an amount of <=15 pts.wt. per 100 pts.wt. of the composition. The composition is mixed with water in a water/binder weight ratio of 0.3-0.5, when used as a binder. When the composition is used for the curing of the mortar or concrete, the mortar or concrete is aged under a saturated steam condition of 40-80 deg.C for 2-24hr in order to improve the compression strength of the mortar or concrete.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic composition for mortar, concrete, etc. used in the fields of architecture and civil engineering, and a method for producing high-strength mortar and high-strength concrete using the same.

0002

BACKGROUND OF THE INVENTION Blast furnace slag powder inherently has latent hydraulic properties, and has been mixed with cement, gypsum, etc. to produce blast furnace cement and commercially available. Concrete for various uses is also manufactured by separately measuring, mixing, and kneading cement, pulverized blast furnace slag, other admixtures, and aggregates in a batcher plant. The blast furnace slag powder used in these applications usually has a Blaine specific surface area of about 4,000 to 4,500 cm2/g. Furthermore, recently, fine slag powder has been atomized using classification means to achieve a Blaine specific surface area of 8,000 cm2/g.
This is sometimes used in place of conventional fine slag powder for the purpose of obtaining high strength, etc. (``Proceedings of the 8th Annual Conference on Concrete Engineering'', 1986,
pp289-292).

[0003] Further, as an example of a hydraulic composition containing fine particles, inorganic solid particles A have a particle size of 50 Å to 0.5 μm, solid particles B have a particle size of 0.5 μm to 100 μm, and are one order of magnitude larger than the particles A. A hydraulic composite material containing a surface active dispersant is known (Japanese Patent Publication No. 59182/1982). Solid particles A are, for example, silica fume, solid particles B
is, for example, Portland cement.

0004

[Problem to be solved by the invention] Normal Blaine value 4,
Fine slag powder of about 500 cm2/g has the disadvantage that although it has hydraulic properties, its initial strength is lower than that of ordinary Portland cement, and it is also difficult to obtain high strength. Further, although the fine powder having a Blaine value of about 8,000 cm2/g obtained by classifying the above-mentioned granulated blast furnace slag powder has high strength, the initial strength at 3-day age is still low.

[0005] This is an example of concrete using silica fume as an admixture, for which research results have been recently announced, but in this case, unless the water/binder ratio is kept below 0.30, The problem is that ultra-high strength cannot be achieved, and the concrete is sticky and has poor workability due to the addition of a large amount of high-performance water reducing agent. The present invention aims to effectively utilize the hydraulic properties of blast furnace slag itself to obtain a hydraulic composition that can obtain high strength more easily than before.

[0006]

[Means for solving the problem] The above problem is solved by
This problem is solved by a hydraulic composition consisting of cement and vitreous blast furnace slag powder whose μm passage is 90% by weight or more of the blast furnace slag powder.

[0007] The vitreous blast furnace slag powder used in the hydraulic composition of the present invention has a particle size of 10 μm in the amount of 90% or more by weight, and the particle size of the 5 μm particle in the pulverized blast furnace slag powder is 50% by weight. % by weight or more and 80% by weight or less, and 1μ
It is preferable that the amount passing through m is 10% by weight or more and 20% by weight or less. This preferred range of particle size distribution is indicated by diagonal lines in FIG. Such fine powder may be obtained by pulverizing vitreous blast furnace slag such as granulated blast furnace slag using a known pulverizer, or by pulverizing vitreous blast furnace slag such as granulated blast furnace slag, or by pulverizing it for use in cement, for example, with a Blaine value of 4,000 to 4. , 500 cm2/g or so.

Cement itself forms a hydrated structure and has an alkali stimulating effect on slag powder. Specifically, it is Portland cement or a mixed cement containing at least 30% of Portland cement.

The ratio of the vitreous blast furnace slag powder to the cement is 20 to 80% by weight, preferably 40 to 60% by weight, and therefore 80 to 20% by weight of cement.
, preferably 60 to 40% by weight. If it is less than 20% by weight, the effect of slag will not be exhibited, and if it exceeds 80% by weight, there will be too little cement, which is also a reaction stimulant for slag.

[0010] The above-mentioned hydraulic composition has a lower amount of SO3 than ordinary Portland cement. Therefore, higher strength can be obtained by adding SO3 in the form of powdered gypsum. This stone can be used in dihydrate, semi-hydrate, or anhydrous format. The appropriate amount of gypsum to be added is 15 parts by weight or less, preferably about 2 to 8 parts by weight, based on the amount of SO3, per 100 parts by weight of the sum of ground blast furnace slag powder and cement. The reason why the maximum amount of SO3 is set to 15 parts by weight is that if more than this amount is added, there is a risk of abnormal expansion of the hardened body, and there is also a risk that the steel material in the hardened body may be corroded.

[0011] In order to obtain high strength by using the hydraulic composition of the present invention as a binder for concrete and mortar, water/
The binder ratio needs to be about 0.5 to 0.3 in terms of weight ratio. If it is larger than 0.5, the density of the cured product will be poor;
If it is smaller than 3, the result will be concrete with high viscosity and poor workability, such as concrete mixed with silica fume, and water will be too small from the reaction surface of the slag. It goes without saying that sand, gravel, etc. are mixed into ready-mixed concrete and ready-mixed mortar as aggregate.
The blending amount may be the same as when conventional cement is used as a binder.

[0012] Although the curing to harden the fresh mortar and fresh concrete may be carried out at room temperature, strength can be developed in a short period of time by carrying out steam curing at 40°C to 80°C. This steam curing is carried out at the above temperature in the presence of saturated steam, and specifically, in order to maintain saturated steam, the molded water-containing composition is placed in a closed room or wrapped in vinyl, and then exposed to saturated steam. Maintain the condition during curing. The appropriate curing time is 2 hours to 24 hours, and optimally 4 to 1 hour.
Approximately 2 hours is suitable from the viewpoint of strength and economy.

[0013]

[Effect] Glassy blast furnace slag is not crystallized, so
Even when pulverized, the composition does not change depending on the particle size. Therefore, atomizing the slag increases the surface area per unit weight and increases the reactivity of the slag at its initial stage. Therefore, in order to increase the strength at the initial age (especially about 3 to 7 days), it is necessary to ensure a highly reactive fine particle content. In the hydraulic composition of the present invention, not only the initial strength but also the final strength of the hardened product is enhanced by pulverizing the blast furnace slag into ultra-fine powder and combining it with cement.

By the way, if the particles are all composed of ultrafine particles of 1 μm or less, there will be nothing to react with over a long period of time, resulting in poor long-term strength growth. Therefore, we added 10 to 20 particles of 1 μm or less, which are ultrafine particles of vitreous blast furnace slag powder.
By adjusting the weight percent of particles of 1 to 5 μm and particles of 5 to 10 μm, which contribute to long-term strength, to the above ratios, it is possible to satisfy both the improvement in initial strength and the elongation of long-term strength.

[0015]

[Examples] Example 1 Granulated blast furnace slag powder having a particle size within the range of the present invention was prepared by the following procedure. Granulated slag, which is a raw material with an average particle size of 1.2 mm, was made into an average particle size of 13.5 μm using a ball mill, and the powder was classified to have an average particle size of about 3 μm. A vitreous blast furnace slag powder indicated by the solid line in Figure 1 was obtained. Its Blaine specific surface area was 12,300 cm2/g. For comparison, the particle size distribution of granulated blast furnace slag powder with a Blaine specific surface area of 4,500 cm2/g is shown in the same figure with a dashed line, and the particle size distribution of granulated blast furnace slag powder with a Blaine specific surface area of 8,000 cm2/g is shown in the same figure. Each is indicated by a broken line in the figure.

A hydraulic composition was obtained by mixing 200 kg of the above pulverized blast furnace slag with 200 kg of ordinary Portland cement (manufactured by Daiichi Cement Co., Ltd.).

This hydraulic composition contains 160 kg of water, 1026 kg of gravel (hard sandstone), 807 kg of sand (river sand), and a high performance water reducer (Leopild 8N, Bozoris Bussan)6.
00 kg were mixed to prepare fresh concrete. For comparison, 200 kg (
400 kg in total) of the same ordinary Portland cement (Comparative Example 1), granulated blast furnace slag powder with a Blaine specific surface area of 4,500 cm2/g (Comparative Example 2), or Blaine specific surface area of 8
,000cm2/g of granulated blast furnace slag powder (Comparative Example 3)
A comparative example of ready-mixed concrete was prepared using the following method. Cement, water, gravel, and sand were the same as in Examples, but the high-performance water reducing agent was 4.96 kg in Comparative Example 1, and 4.96 kg in Comparative Examples 2 and 3, in accordance with the difference in adsorption capacity of cement and slag. was set at 4.40 kg each. In addition, in Comparative Example 1 where no slag was used, cement was added from 400 kg to 533 kg.
Comparative Example 4 was prepared by increasing the amount of gravel from 1,026 kg to 1,020 kg, reducing the amount of sand from 807 kg to 719 kg, and increasing the amount of high performance water reducing agent to 9.38 kg. In Example 2, half of the cement in Comparative Example 4 was made from the product of the present invention, and sand, gravel, and water reducing agent were adjusted so as to obtain approximately the same level of slump as in Comparative Example 4. Table 1 shows the mixing ratio of each fresh concrete. Each fresh concrete was poured into a 10cmφ x 20cm formwork, cured for 1 day in a curing room at 20℃ and 80% RH, removed from the mold, and cured in water at 20℃ to change compressive strength over time. The results of the measurements are shown in Table 2.

[0018]

[Table 1]

[0019]

[Table 2]

The product of the present invention has almost the same strength as Comparative Example 1, which does not contain slag, after 3 days of wood age, and after 7 days, it suddenly has a strength that greatly exceeds that of Comparative Example, and after 28 days, it has reached the same level of strength as Comparative Example 1, which does not contain slag.
,000kgf/cm2. On the other hand, Comparative Example 2 uses normal fine slag powder, but compared to Comparative Example 1, it cannot exceed the strength of Comparative Example 1 even after 91 days of age. Comparative example 3 has a Blaine specific surface area of 8,000 cm2
/g of slag, but after 28 days, results were obtained in line with conventional knowledge, which surpassed the strength of Comparative Example 1, but the product of the present invention obtained a strength that greatly exceeded that. In addition, Comparative Example 4 has a water-cement ratio of 0.30, which is considered to be the limit of the current practical level.
1.0 slag-free formulation even after 91 days
00 kgf/cm2, demonstrating the superiority of the product of the present invention. Example 2 has a water-cement ratio of 0.30 (cement in this case is the product of the present invention), but the initial strength is large and at 91 days old, it is equivalent to Example 1, but compared to Comparative Example 4. The superiority of the invention is clear.

Example 2 Fresh concrete was prepared by adding 7% SO3 anhydrite to the product of Example 1, and its strength development was investigated.

[0022]

[Table 3] As mentioned above, the effect of developing strength at the initial wood age is large.

Example 3 The product of Example 1 was cast, left in air at 20°C for 2 hours, and then steam-cured at 60°C for 8 hours. The material was left to cool and a strength test was conducted when the material was 7 days old. As a result, 1,070kgf
/cm2 strength was obtained, and the result of steam curing was recognized.

[0024]

As described above, according to the present invention, by adjusting the viscosity of the granulated blast furnace slag powder, the initial strength of the hydraulic composition is increased, and the long-term strength is also increased. By limiting the proportion of cement, we were able to effectively utilize the reactivity of slag. An improvement in initial strength was observed with the addition of gypsum. For example, concrete with a water/binder ratio of 0.4 has a 28-day wood age of 1,000
The hydraulic composition of the present invention is effective as a hydraulic composition for high-strength concrete and mortar, as concrete with a strength exceeding kgf/cm2 was obtained. In addition, steam curing increases the reactivity of slag, so it is possible to obtain 28-day strength after 7-day aging, and is an economically effective concrete manufacturing method.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the particle size distribution of fine blast furnace slag powder used in the hydraulic composition of the present invention.

[Explanation of symbols]

1...Slag powder used in Examples

Claims (6)

[Claims] Claim 1: A hydraulic composition comprising cement and vitreous blast furnace slag powder whose particle size passing through 10 μm is 90% by weight or more of the blast furnace slag powder. 2. Hydraulic properties according to claim 1, wherein the particle size passing through 5 μm is 50% to 80% by weight of the pulverized blast furnace slag powder, and the particle size passing through 1 μm is 10% to 20% by weight. Composition Claim 3: The powdered blast furnace slag is used as a hydraulic composition.
The hydraulic composition according to claim 1, wherein the proportion is 0 to 80% by weight and the remainder is cement. 4. Hydraulic composition 100 according to claim 3.
Hydraulic composition comprising 15 parts by weight or less of powdered gypsum as an amount of SO3 based on parts by weight 5. Using the hydraulic composition according to claim 1, 2, 3, or 4 as a binder, the water/binder ratio is 0.3 by weight.
Fresh mortar or fresh concrete with ~0.5 6. A method for producing mortar or concrete, comprising curing the fresh mortar or fresh concrete according to claim 5 under saturated steam at 40 to 80°C.