JPH0157065B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing unfired artificial aggregate, and particularly to a method for manufacturing unfired artificial aggregate using only the heat generated during hardening of cement. Conventionally, the method of producing unfired artificial aggregate without using a firing method involves granulating a mixture of aggregate raw materials, water, and cement into granules of an appropriate size, and then leaving them exposed to the atmosphere. Two methods are well known: leave-on curing, in which the material is left to cure, and steam curing, in which it is cured in a steam atmosphere. However, the former method requires a long time for curing and therefore requires a vast amount of land. Another problem was that it was difficult to obtain uniform aggregate because it was greatly affected by environmental conditions such as weather and season. On the other hand, although the latter method allows high-strength aggregate to be obtained in a short period of time, it requires a separate heating device and fuel costs, leading to high product costs. Therefore, the present inventors have conducted various research into new methods for producing artificial aggregates that solve the problems that existed in each of the conventional methods for producing artificial aggregates as described above, and as a result, they have developed an invention. They focused on the use of self-heating of the cement mixed into the aggregate raw material during the production of artificial aggregate, and completed a new method for producing artificial aggregate that uses this heat to cure the artificial aggregate. be. That is, the present invention involves granulating a mixture of aggregate raw materials, water, and cement into granules of appropriate particle size, and then granulating the granules into a curing box with a structure that is heat insulating and prevents moisture from escaping. It is characterized in that it is filled with cement and then left as it is to cure using only the heat generated during cement hardening. The present invention will be explained below. First, water and cement are added to the aggregate raw material, and the mixture is thoroughly mixed according to a conventional method. Aggregate raw materials include limestone, clay, slag, flyash, and other materials.
The seed or two or more types are used and the particle size is adjusted in advance to an appropriate particle size depending on the particle size of the aggregate to be obtained.
Further, as the cement, any cement such as ordinary Portland cement, early strength Portland cement, alumina cement, etc. can be used. The mixing ratio of these and cement is approximately 5 to 50 parts by weight of cement to 100 parts by weight of the aggregate raw material, and the mixture is thoroughly mixed. If the amount of cement is less than 5 parts, sufficient bonding strength cannot be obtained, and if it is more than 50 parts, economic efficiency will be impaired. Next, an appropriate amount of water is added to this mixture, and the mixture is granulated into granules of appropriate size using various granulation methods such as pressure molding and rolling granulation. The particle size during this granulation is 5 mm or less in the case of fine aggregate, and 5 mm or more and approximately 30 mm or less in the case of coarse aggregate. Next, the granules thus produced are quickly filled into a curing box, subjected to a hydration reaction, and then hardened and cured. That is, the granules are put into a curing box that has a heat insulating wall and has a structure that prevents moisture from escaping, and the aggregate produced from the curing box is put into a curing box that has a predetermined strength. Take it out. The curing box used here is
It has a heat insulating layer on its side wall to prevent the heat generated by the curing of the granules filled therein from dissipating to the outside, and has a structure that prevents moisture from escaping. Note that the shape and size of this curing box may be arbitrary. An example of the curing box here is as shown in the figure. In the figure, reference numeral 1 indicates the entire curing box, which consists of a container 2 and a top lid 3 provided on the top thereof. The container 2 has a cavity in which the granular material 4 is filled, and a side wall 5 of the cavity is filled with a heat insulating material 6.
Further, the upper lid 3 is adapted to fit tightly into the container 2, so that heat and moisture are not dissipated to the outside. The heat insulating material used here may be one or more of organic foam materials such as polyurethane foam and styrene foam, and inorganic materials such as perlite, insulation bricks, glass fiber, asbestos, and silica fiber. Note that the heat insulating material used here must be made of a material that can withstand high temperatures because the granules filled inside generate heat. In addition, the structure of the curing box should be strengthened by using reinforcing materials or other materials as necessary. Alternatively, the curing box may be provided with an air layer on the side wall without using a heat insulating material to obtain a similar heat insulating effect. As described above, the present invention involves placing granules for aggregate, which have been granulated in advance using cement as a binder, into a curing box with an insulating and closed structure, in which the heat of hydration reaction generated during hardening is absorbed. Since all of the waste is utilized and cured, aggregates can now be obtained without any fuel costs compared to conventional methods of producing artificial aggregates. Furthermore, since the present invention uses a closed mold to prevent moisture from escaping, the resulting product can have high strength as if it had been cured in a steam atmosphere. Examples of the present invention will be described below. Example 1 Table 1 shows the ordinary cement used here, and Table 2 shows the fly ash used as the aggregate raw material. The above ordinary cement and fly ash were thoroughly mixed at a mixing ratio of 50:50. Next, put this mixture into a pan-shaped pelletizer (diameter 700φmm, depth 150mm), and add approximately
By continuing to sprinkle 20% water, granules having a particle size of about 5 to 20 mm were granulated. Immediately after granulation, approximately 25 kg of the pellets were put into a separately prepared curing box until it was almost full, and then cured. The curing box used here has the structure shown in Figure 1, and its size is cylindrical with an internal diameter of 300 mm and an internal height of 400 mm.The side walls are lined with foamed styrene with a thickness of about 70 to 100 mm. is inserted. For comparison, some of the granules mentioned above were
It was placed in a drying room at ℃ (relative humidity 45%) for dry curing. In addition, a part of the granular material was cured for one day at 20°C in a humid air (relative humidity of 90% or more) and then cured in water at 20°C.

【table】

[Table] As a result, approximately 5 hours after the granules were put into the curing box, intense heat generation occurred as the cement hardened.
The temperature continues to rise for about 1 day. The maximum temperature is approximately 70℃
The heat storage temperature increased approximately 50°C above room temperature.
The point pressure strength of the aggregate thus obtained was 98 Kg/cm ² after curing for 3 days in a curing box. On the other hand, in the case of water curing at 20℃, 60%
Kg/cm ² , 92Kg/cm ² at 28 days old. Also 50℃
In the case of dry curing (45% relative humidity), 12
It was Kg/ ^cm2 . From this perspective, conventional
According to the present invention, the strength that can be achieved by curing in water at 20°C for 28 days can be achieved in just 3 days. Furthermore, when dry curing is performed at a relative humidity as low as 45%, the strength development is extremely low even when curing at a temperature of 50°C, which is about the same as when the heat storage temperature is raised. In addition, the absolute dry specific gravity of aggregates was measured when measuring the strength of aggregates obtained by curing in curing boxes and aggregates obtained by dry curing, and when measuring the absolute dry specific gravity of aggregates obtained by curing in water. Aggregate is 7 days old, JIS
It was carried out in accordance with A1135. The strength test was carried out by applying pressure from above and below the pellet, and the load at breakage was expressed as the value divided by the cross-sectional area passing through the center of the pellet sphere. Example 2 As in Example 1, the ordinary cement and fly ash shown in Tables 1 and 2 were used.
The ratio of ordinary cement to fly ash is (20:80)
An artificial aggregate was obtained in the same manner as in Example 1 except for the following. As a result, aggregate obtained by curing in water has a point pressure strength of 24 Kg/cm ² at 7-day age and 34 Kg/cm ² at 28-day age, but aggregate obtained by curing in a curing box has a ,
A material with high strength of 22 Kg/cm ² at 1-day age and 45 Kg/cm ² at 3-day age was obtained. The heat storage temperature rise at this time was approximately 20°C due to the small amount of cement. However, even this slight amount of heat generation had a significant effect. Moreover, the absolute dry specific gravity was 1.6 g/cc. Example 3 The same ordinary cement and fly ash as in Example 1 were used, the mixing ratio was set to 20:80, and granules with a particle size of 5 to 20 mm were made in the same manner as in Example 1 to about 2 ^m3 . It was grainy. Approximately half of this amount is 1 m ³
The granules were placed in a curing box with an internal diameter of 900φmm, an internal height of 1240mm, and a sidewall insulation material thickness of 200mm, so that they were completely filled to the brim, while the remaining granules were piled up inside the room. I left it alone to cure. As a result, the aggregate obtained by curing in the curing box showed a value of 46 kg/cm ² . on the other hand,
The point pressure strength of artificial aggregate obtained by leaving it to cure indoors is 41 kg/cm ² at the center after 28 days of age, but it shows a value of 29 kg/cm ² at the surface, which shows considerable variation. . Note that the room temperature was approximately 15 to 20°C.
Furthermore, the temperature of the center of the indoor pile only rose to 30°C at maximum, whereas in the case of the present invention, the temperature was 45°C. The bone dry specific gravity of both was 1.6 kg/.

[Brief explanation of drawings]

The figure shows a partial sectional view of a curing box used in one embodiment of the method of the present invention. 1 ...Curing box, 2...Container, 3...Top lid, 4...Particles, 5...Side wall, 6...Insulating material.

Claims (1)

[Claims] 1 A mixture consisting of aggregate raw materials, water, and cement is granulated into granules of appropriate particle size, and this is packed into a curing box with a structure that is insulating and prevents moisture from escaping. A method for producing artificial aggregate characterized by leaving it as is and curing it only with the heat generated when cement hardens.