JP3055899B1 - Artificial aggregate and method for producing the same - Google Patents

Abstract

The present invention provides a high-strength artificial aggregate that can be easily manufactured by effectively using coal ash and waste glass, and has high crush strength. SOLUTION: 5 parts to 100 parts of soda lime glass powder and 5 parts of cement to 100 parts (weight ratio) of coal ash powder.
Add 30 parts and water, knead, granulate and 1000 ~ 12C
Bake at 00 ° C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial aggregate for concrete utilizing coal ash and waste glass effectively and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, natural aggregates such as river gravel have been used as aggregates for concrete. In recent years, various types of artificial aggregates have been studied in place of natural aggregates that are being depleted. .

[0003] On the other hand, coal ash, which is waste from thermal power plants, is expected to exceed 10 million tons / year in the coming years due to the expansion of thermal power plants, but it is used as an admixture for concrete. At present, there is no other field that can be used quantitatively.

[0004] In addition, waste glass such as bottles and plate glass is often buried as waste, and there is a demand for applications that can be effectively reused.

[0005] In view of the above situation, coal ash, which is industrial waste, and waste glass that cannot be reused and is landfilled are effectively used, and used as an artificial aggregate as a substitute for natural aggregate. It is considered to be.

Japanese Patent Application Laid-Open No. 7-206491 proposes an effective use of coal ash as an artificial aggregate, which aims at a high-strength lightweight aggregate. And the crushing strength is low in spite of the firing temperature.

Japanese Patent Application Laid-Open No. Hei 9-77530 aims at the effective use of waste glass in addition to the effective use of coal ash. However, since the glass ash is filled between the coal ash particles,
100 to 400 parts of glass is required for 100 parts of coal ash, and fine cracks are easily generated due to a difference in expansion coefficient between the coal ash and the binder of the glass, and the produced aggregate has high crushing strength. It could not be a high-strength artificial aggregate.

[0008]

Accordingly, an object of the present invention is to provide an artificial aggregate which can be easily manufactured by effectively utilizing coal ash and waste glass and has high crushing strength.

[0009]

The artificial aggregate according to claim 1 of the present invention comprises 5 to 100 parts by weight of soda lime glass powder and 5 to 30 parts of cement for 100 parts by weight of coal ash powder.
Add parts by weight and water, knead, granulate, 1000 ° C ~ 1
It is characterized by being formed by firing at 200 ° C.

[0010] The artificial aggregate according to claim 2 is characterized in that a wollastonite phase and anorthite are mainly deposited in the glass binder layer.

[0011] According to these, wollastonite increases the viscosity of the softened glass, the softened glass acts as a binder for binding the coal ash, and further reacts with the coal ash, and mainly forms anorthite in the binding layer. By precipitating the above, it is possible to obtain a high-strength aggregate in which coal ash has a strong mutual bond.

The method for producing an artificial aggregate according to the present invention is characterized in that soda lime glass powder 5 to 1 is used for 100 parts by weight of coal ash powder.
It is characterized in that 00 parts by weight and 5 to 30 parts by weight of cement are kneaded by adding water, granulated, and fired at 1000 to 1200 ° C.

According to this, needle-like crystals of wollastonite are generated from the surface of the finely ground glass and promoted by the calcium component in the cement. Further, wollastonite increases the viscosity of the softened glass, and at this temperature, the glass does not foam, and the softened glass serves as a binder for binding the coal ash. Furthermore, it also reacts with coal ash, predominantly deposits anorthite in the bonding layer, and further strengthens the mutual bonding of the coal ash, whereby an aggregate having strength can be obtained.

The bottle / sheet glass is made of so-called lime / lime glass. It is easily conceived that this glass is mixed with coal ash, granulated, sintered and used as a binder between particles of coal ash.

However, from the viewpoint of the strength of the fired product, at a firing temperature of 1000 ° C., the bond of the coal ash by sintering is weak, and at a temperature of 1100 ° C. or more, the viscosity of the binder glass becomes low, and the unburned carbon mixed with the coal ash is reduced. It reacts and foams, causing a reduction in the strength of the aggregate.

However, the present inventors pulverize so-called soda lime-based waste glass to a particle size of 20 to 100 μm, and set the firing schedule from room temperature to 1100 μm, for example.
C. for 2 hours and then for 2 hours in the firing temperature range, needle-like crystals of wollastonite are formed from the surface of the finely ground glass. The wollastonite increases the viscosity of the softened glass, and does not foam at this temperature. Then, it was found out that feldspar was mainly deposited in the bonding layer to strengthen the mutual bonding of the coal ash, and that an aggregate having a large strength was produced.

FIG. 1 is a diagram showing the relationship between wollastonite crystals formed in waste glass (soda-lime glass composition), which is waste of commercial glass bottles, and the crushed particle size of glass.

Heat treatment conditions are from room temperature to 950 ° C.
The temperature was raised over a period of time, maintained at 950 ° C. for 2 hours, and allowed to cool. Sample A is a 2 mm square shape, and Sample B is a powder sample ground to a central particle size of 60 μm.

According to the X-ray diffraction measurement, no crystal peak is observed in the sample A, but a crystal peak is observed in the powder sample B. In other words, it can be seen that wollastonite and devitrite crystals precipitate due to the powdered effect.

Further, in Sample C, 10% of the powder of Sample B was replaced with cement, and the X-ray diffraction peak of Sample B was strong (high). That is, when cement is added to the powdered glass, the crystal amount of wollastonite increases as seen from the peak intensity of the X-ray diffraction data. That is, the addition of cement substantially promotes the crystallization of the powdered glass.

The growth of wollastonite crystals formed from the surface of powdered soda-lime glass is related to the firing temperature and firing time. According to the X-ray diffraction test, when these crystals were heated from room temperature to the set firing temperature in 2 hours, and then kept at the set firing temperature for 2 hours, they first started growing at 800 ° C and disappeared at 1050 ° C. Start. On the other hand, glass of the same composition that is not powdered softens at 700 ° C.
Is in a softened and molten state.

When coal ash is mixed with a mixture of powdered glass and cement, the composition composed of the three raw materials does not soften and melt even at 1100 ° C., and the glass component reacts with the cement and coal ash to form ash. Generates feldspar. When the proportion of coal ash increases, the calcined product does not soften even when the calcining temperature reaches 1200 ° C. By the action of the intervening glass, strength that cannot be expected from coal ash alone is generated, and a fired product having high strength, that is, a high-strength artificial aggregate can be produced.

Next, five types of samples ("E-1" to "E-5") in which the mixing ratio of the raw materials was changed were prepared. Table 1 shows the mixing ratio of each sample, the effect of the firing temperature of each sample on the strength (crushing strength), and the properties of the artificial aggregate obtained by firing each sample using an electric furnace.

[0024]

[Table 1] FIG. 2 is a diagram showing the X-ray diffraction patterns of the artificial aggregate of the two samples (E-3 and E-4), the coal ash as the raw material, and the cement. The main crystals are anorthite, wollastonite and quartz found in coal ash itself.

FIG. 3 is a diagram showing the effect of the mixing ratio of the raw materials and the firing temperature on the strength (crush strength). The crushing strength increases as the amount of powdered glass in the raw material ratio increases and as the firing temperature increases, but the strength decreases under heat treatment conditions in which the glass softens and melts and foams. The absolute specific gravity also shows the same tendency as the strength, and the specific gravity increases. The specific gravity decreases when the glass is softened, melted, and foamed. The tendency of water absorption is also consistent with the tendency of specific gravity. In any case, the properties of the artificial aggregate vary depending on the powder glass content.

FIG. 4 is a view showing the appearance of the strength of the bond between the sintered body of coal ash alone and the sintered body of glass ash and cement added to the coal ash (SEM photograph of fracture surface of aggregate). . The former shown in (A) in the figure (E-1, 1100 ° C, powder glass 0 parts)
In, coal ash is fused together, but there are many gaps,
The latter (E-3, 1100 ° C., powdered glass 60 shown in FIG.
In part (a), a crystal layer is formed in the gap between the coal ashes, and a state in which a physically and chemically strong bond is formed is observed.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for producing an artificial aggregate according to the present invention will be described.

Powdered glass and cement are added to coal ash, water is added, and the mixture is kneaded and granulated. If the granulated material is dried and fired, a lightweight and high-strength granular aggregate can be obtained. In the actual production process, 15 to 40 parts of soda lime glass powder and 100 to 50 parts of cement are added to 100 parts of coal ash by weight, and 20 to 50 parts of water are added and kneaded, and the diameter is about 20 mm through a granulator. A spherical molded body of

After the spherical molded body is dried, it is put into a firing furnace, a predetermined time is taken up to a firing temperature range, the firing temperature range is maintained at 1100 to 1200 ° C. for a certain time, and then the fired product is allowed to cool. . Fired product, crushing strength 600-1000Kg
The artificial aggregate of f was obtained.

The raw material coal ash is obtained by crushing fly ash, bottom ash, cinder ash, etc.
About 30 μm was appropriate in terms of the total central diameter.

The powdered glass may be crushed waste glass (especially colored glass, which cannot be recycled into a transparent, brown bottle or plate glass, and is usually used for landfill disposal). Most of them were soda-lime glass and had a total central diameter of about 30 μm.

As the pulverizer, a vertical mill or a ball mill may be used. As the cement, inexpensive ordinary Portland cement was used, but other types of cement may be used. If the strength of the unfired granulated product may be low, it can be replaced with lime or gypsum.

In order to granulate the above three raw materials, the amount of water to be added is about 30% or less, and the amount is determined by the characteristics of the mixing, kneading and granulating machines. Is preferably low in water content. As the granulator, either a pan type or a pressure extrusion type can be used.

The granulated spherical compact having a diameter of about 20 mm is placed in a dryer. The dried molded body had also finished its initial hardening as concrete, and had a strength of 40 (30 to 50) Kgf, which was enough to withstand subsequent handling.

As a firing machine for the spherical molded body, a rotary kiln is preferable in terms of cost, but a shuttle kiln, a tunnel kiln, or the like may be used. In the firing schedule, it takes 2 hours from room temperature to firing temperature, 1000-1200 ° C.
It took 2 hours in the baking area. Thereafter, the mixture was allowed to cool to obtain a granular artificial aggregate.

The performance of this aggregate is absolutely dry specific gravity of about 2, water absorption of 1% or less, and crush strength of 500 kgf or more. As will be described later, this aggregate passed the condition of trial mixing of concrete as an ordinary aggregate.

The present invention: 100 parts of coal ash powder (weight ratio)
5 to 100 parts of soda-lime glass powder and 5 to 30 parts of cement are added to water, kneaded, granulated, and
The artificial aggregate is manufactured by firing at ~ 1200 ° C. The reason that the soda lime glass powder is limited to 5 to 100 parts with respect to 100 parts (weight ratio) of coal ash is that the glass powder must be less than 5 parts. Is less than 100 parts, and if it exceeds 100 parts, it is easy to soften and melt, and a strong artificial aggregate cannot be obtained.

The reason why the amount of cement is limited to 5 to 30 parts with respect to 100 parts (weight ratio) of coal ash is that if less than 5 parts, the effect of adding cement, that is, the addition of cement is substantially The effect of promoting the crystallization of glass is small, and the strength of the unfired molded product is small.
This is because if it exceeds the part, there is a risk of explosion at the time of firing, and there is a possibility that the cost becomes too high.

Although the above description of the present invention mainly focuses on the production of coarse aggregate, it is also possible to produce fine aggregate by changing the size of the compact or by crushing the artificial aggregate.

Next, the aggregate of the present invention was actually manufactured.

As a main raw material, 100 parts (weight ratio) of coal ash finely pulverized to a center particle diameter of 50 μm in advance,
0 parts and 20 parts of cement were mixed and mixed well, and 40 parts of water was sprayed to obtain a spherical molded body having a diameter of about 20 mm by a pan-type granulator. After the molded body was dried for two days in the sun, it was arranged in a mortar, placed in an electric resistance heating kiln, kept at 1100 ° C. for 2 hours, kept at 1100 ° C. for 2 hours, and then allowed to cool in the kiln.

The properties of the baked artificial aggregate E-3 were measured according to JIS.
Table 2 shows the compatibility of the coarse aggregate specified in A5005.

[0043]

[Table 2] The artificial aggregate (E-3) has the prescribed requirements except for the value of the absolute specific gravity. In general, it is recognized that natural aggregates having a low absolute dry specific gravity are porous and weak, so that an absolute dry specific gravity of 2.5 or more is necessary. However, in the aggregate of the present invention, the absolute dry specific gravity is 1.8.
However, because of its low water absorption and high crushing strength, it is not inferior to concrete aggregate. Conversely, there is an application that makes use of its light weight and high strength properties, leading to the effect of the aggregate of the present invention.

The concrete was kneaded using the aggregate of the present invention. The mixing ratio is as shown in Table 3.

[0045]

[Table 3] Table 4 shows the properties of the hardened concrete.

[0046]

[Table 4] The concrete using this aggregate is 10% lighter than the normal concrete specific gravity, as predicted from the absolute dry specific gravity of the aggregate. Compared with natural crushed stone, the compressive strength and static elastic modulus (28 days) of concrete using the aggregate of the present invention show the same or higher values, and natural crushed stone can be sufficiently substituted for concrete aggregate. However, it is clear that the aggregate is more suitable for higher strength.

The aggregate of the present invention is not a commercially available lightweight aggregate mainly composed of coal ash, but rather is similar to a natural coarse aggregate having high strength. Since it belongs to the lightweight aggregate, the weight of the concrete structure can be reduced, and the cost of the building can also be reduced.

[0048]

As described above, according to the present invention, an artificial aggregate can be easily produced by effectively utilizing a large amount of coal ash and waste glass treated as waste. The resulting artificial aggregate can have unprecedented high strength.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between wollastonite crystals generated in waste glass and the ground particle size of glass.

FIG. 2 is a diagram showing X-ray diffraction patterns of artificial aggregate using a sample, coal ash as a raw material, and cement.

FIG. 3 shows that the mixing ratio of raw materials and the firing temperature are strength (crush strength)
FIG.

FIG. 4 is a view showing how the strength of bonding of a sintered body is developed.

[Explanation of symbols]

 (A) Sintered body of coal ash only (B) Sintered body obtained by adding glass and cement to coal ash

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B09B 3/00 303A (72) Inventor Tsuyoshi Morita 5-14-10, Nishitenma, Kita-ku, Osaka Kinki Concrete Industry Co., Ltd. (72) Inventor Haruyoshi Yoshida 5-14-10 Nishitenma, Kita-ku, Osaka Kinki Concrete Industrial Co., Ltd. (56) References JP-A-9-77541 (JP, A) JP-A-11-116301 (JP, A) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 18/10 C04B 18/08 C04B 18/16

Claims (3)

(57) [Claims] 1. To 100 parts by weight of coal ash powder, 5 to 100 parts by weight of soda-lime glass powder, 5 to 30 parts by weight of cement and water are added, kneaded, granulated, and cooled to 1000 ° C. to 12 ° C.
An artificial aggregate formed by firing at 00 ° C. 2. An artificial aggregate characterized in that a wollastonite phase and anorthite mainly precipitate in a glass binder layer. 3. A soda-lime glass powder of 5 to 100 parts by weight and a cement of 5 to 30 parts per 100 parts by weight of coal ash powder.
Add parts by weight and water, knead, granulate, and
A method for producing an artificial aggregate, characterized by firing at 00 ° C.