JPS638248A - Quality improver for cement and concrete - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention addresses the problem of the use of fly ash, which will become more and more problematic in the future due to the reduction in coal combustion temperature due to environmental regulations and the increased use of foreign coal with a different chemical composition and high melting point. It is of course related to quality improving materials that can be widely applied to cement/concrete products and cement/concrete structures in general.

[Conventional technology]

Currently, in our country, about 70 tons of coal ash is extracted as fly ash. Approximately 20 tons of this waste is reused as cement admixtures and cement raw materials, and the remainder is disposed of in landfills.

However, in recent years, due to the increased use of overseas coal and problems with combustion temperatures, the quality of fly ash is expected to decline year by year, making it difficult to use the raw powder as it is for cement additives, etc. This is expected to continue.

Conventionally, fly ash has been used as a concrete admixture without classifying raw powder, and has been widely used to improve the workability of concrete and promote pozzolanic reactions.

[Problem that the invention seeks to solve]

Due to lower combustion temperatures due to environmental regulations or the use of foreign products with different chemical compositions and higher melting points, the physical and chemical properties of fly ash change, resulting in a decrease in the proportion of spherical particles and hollow particles that improve the workability of concrete. The proportion of particles with poor shape, such as particles and loose particles, is increasing.

In addition, an increase in the amount of unburned carbon (influenced by an increase in the amount of air in the concrete) occurs.

In particular, fly ash has been found to have poor reactivity due to the above-mentioned reasons regarding the pozzolanic reaction, which increases the strength of concrete.

In general, fly ash whose physical and chemical properties such as loss on ignition and amount of SiOz do not satisfy the JIS standard values, and fly ash with little water reduction effect, are extracted.

In view of the above-mentioned points, the present invention aims to improve the effective utilization of fly ash in response to the deterioration in quality of fly ash, and has developed a quality-improving material capable of producing high-strength, dense, and high-quality concrete products and concrete structures. The purpose is to provide the following.

[Means for solving problems]

By grading and selecting fine powder with a particle size range of about 20 microns or less, and mixing it with cement and concrete, it is intended to achieve greater effects than conventional methods.

Furthermore, by sorting the particle size range to 100%, adding a high-performance water reducing agent, and mixing it with cement and concrete), it is possible to improve the quality by several steps.

More specifically, the present invention is constructed by arranging a classification device in an electrostatic precipitator and a seven-liquid storage hopper in a coal-fired power plant, and including a device for continuously classifying particles into a particle size range of 20 microns or less.

In addition, in order to further improve the quality of concrete, 7.0
It is desirable to include a device for adding a high performance water reducing agent to the litash.

[Action/Examples/Effects]

The fly ash that is classified and sorted into small particle sizes from the device configured as above has the following characteristics compared to that of milled powder! However, the comparison describes the classification effect on flour milling.

In addition, if a small amount of high-performance water reducing agent is added to classified fly ash and mixed with cement/concrete, it will have a synergistic effect and will not only reduce water but also increase strength. However, the comparison is based on the effect on flour milling. .

Hereinafter, various embodiments of the present invention will be explained in comparison with conventional ones, and each performance will be explained separately.

(1) Specific Gravity Figure 1 shows the distribution of specific gravity according to the particle size range of fly ash, and the tendency is that the smaller the particle size, the larger the specific gravity. However, FA is fly ash.

(2) Particle shape According to the microscopic photographs, the smaller the particle size of each sample of classified fly ash, the higher the proportion of spherical particles, and the limit is around 20 microns.

(3) Chemical reactivity As shown in Figure 2, 5iOz+At of fly ash
! Regarding the reactivity of 08 with Ca(OH)z of cement, 5 micron classification FA is thicker than that of flour milling.

(4) Unit water ratio As shown in FIGS. 3 and 4, the unit water ratio generally becomes smaller as the particle size becomes smaller.

(5) Water reduction effect As shown in Figures 5 and 6, the water reduction effect when no high performance water reducing agent is added to classification 7 litash is 10% different from 5 chills when compared to flour milling.

(6) Strength development effect (compression/bending) As shown in FIGS. 7 and 8, the compressive strength when mixed with classified ply ash is 15S to 30S or more different from that of powdered powder.

Furthermore, as shown in FIGS. 9 and 10, the bending strength also shows a strength development proportional to the compressive strength.

(7) Effect of reducing drying shrinkage As shown in Figures 11 and 12, the amount of drying shrinkage when mixed with classified fly ash was reduced by 20 to 25% compared to milling.

(8) Effect of reducing water permeability As shown in Figures 13 and 14, the water permeability when mixed with Class 7 litash was reduced by 20 to 50% or more compared to milling.

[Brief explanation of drawings]

1 to 14 are diagrams showing the differences in performance of the product according to the present invention compared to the conventional product. Representative Patent Attorney Misao Ueyama 1 Figure 1 Blue 2 Figure (SrOz + A12 (h Co's anti-forgetfulness (%)) 3
Ratio of figure unit water volume (Ok'n blue 4 figure -+ 5 figure's wheel ■L's ratio f'/,) Ratio/%) Numbness 8 Figure pressure J strong cliff upper level + 9 Figure curved blade 1 return upper level /'/) Su 10 Figure 3 sub-level upper level (ヅ→ Female eyes) The ratio of θv't (al, n temple) f28 The ratio of the dry bombing

Claims (2)

[Claims] (1) Of the coal ash emitted during coal combustion, fly ash is classified without being crushed and the fine particles of 20 microns or less are mixed into cement and concrete to change its physical and chemical properties. A quality improving material for cement and concrete, which is characterized by improving the quality of cement and concrete. (2) Coal ash is classified and an appropriate proportion of a high performance water reducing agent (liquid or powder) is added to the fine particles of 10 microns or less, and the mixture is mixed into cement/concrete.
Quality improving material for cement and concrete as described in ).