JPH10291848A - Production method of subbase course material consisting of fly ash as main component and artificial crushed stone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of economically producing a strong subbase course material consisting essentially of fly ash such as coal ash as a main component. SOLUTION: A paste consisting of 80-95% fly ash such as coal ash, 5-20% cement and 20-25% water by an external compounding ratio is charged into a mold and the paste is applied to a press molding under an pressure of >=40 kg/cm<2> . After the subbase course material is aged, and solidified, is crushed to obtain the subbase course material. The subbase course material has an advantage capable of dispensing with a releasing agent, a water reducing agent, a thickener without necessitating many molding flasks and being different from a cast molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roadbed material mainly composed of fly ash and a method for producing artificial crushed stone.

[0002]

2. Description of the Related Art As an effective method of using fly ash such as coal ash generated in large quantities from a thermal power plant, fly ash is mixed with water and cement to solidify, and the solidified material is crushed to form crushed stone-like roadbed material. It has been proposed to manufacture. In this case, it is simple to cast and mold using a mold, but there are many problems as described below.

[0003] Many molds are required in proportion to the production volume. For automation, equipment for arranging and removing the molds is required, and the equipment requires complicated operations, which is likely to cause a failure. It is necessary to apply a release agent to each mold, and it is not easy to remove the mold from the mold due to tightening during solidification. It is necessary to add 25 to 50% of water to 100% of the mixture of fly ash and cement to obtain a slurry that can be poured. However, since the properties of fly ash vary depending on the coal production area and furnace type, Fluidity changes drastically even when the water content changes by about 0.5%, so adjustment is not easy. If the amount of water is excessively increased, the strength of the solidified body will be reduced. In order to increase the strength of the solidified product, expensive water reducing agents and AE agents must be added.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and is intended to economically produce a crushed stone roadbed material mainly composed of fly ash without using a formwork. The purpose of the present invention is to provide a method of manufacturing a roadbed material that can be used.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a mixture of 80-95% of fly ash and 5-20% of cement, in which 15-25% of water is externally added. ,
The obtained slurry is subjected to press molding, the molded body is cured, solidified, and then crushed. It is preferable that the press molding is performed at a pressure of 40 kg / cm ² or more. As a result, the roadbed material can be manufactured without using a large number of molds as in the related art, and the equipment can be simplified, and the mold release agent, the water reducing agent, the thickener, etc. can be omitted, so that it is economical is there. Further, the amount of water to be added can be kept low, and there is no need to further adjust the water content.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
Will be described in detail along with the flow sheet. In the present invention,
First, fly ash such as coal ash and cement are mixed with powder (mixing 1 in FIG. 1), and then water is mixed. The mixing ratio of fly ash and cement is such that fly ash is 80-95% and cement is 5-20. If the ratio of cement to fly ash is lower than 5%, the strength is insufficient. Conversely, if the ratio of cement exceeds 20%, the economic efficiency is impaired and the object of the present invention of effective use of fly ash cannot be achieved.

Mixture of this fly ash and cement
20 to 25% of water is externally added to 100% (mixing 2 in FIG. 1) to obtain a slurry. At this time, unlike the conventional casting, no water reducing agent or thickener is required. In addition, the amount of water was 25 to 50% in the case of the conventional casting, but is considerably smaller in the present invention. But the amount of water
If it is less than 15%, the fluidity is poor and it becomes difficult to supply the material to the press mold. On the other hand, if it exceeds 25%, it becomes a slurry and cannot be pressed.

[0008] The paste thus obtained is press-formed using a forming die. Unlike a casting mold, a small number of molding dies can process a large amount of fly ash. The molding die is preferably provided with a large radius in order to prevent a decrease in the strength of the corners and to prevent chipping or biting when the molded body is removed. It is not necessary to apply a release agent to the mold.

[0009] The pressure of the press molding is 40 kg / cm ² or more, especially
80-120 kg / cm ² is preferred. 80 kg / cm, sufficient molding strength can not be obtained in less than ² molding pressure rapidly because the pressure disconnected during even pressure holding added molding pressure exceeding 120 kg / cm ^2,
There is not much point in improving strength. In particular, it is not preferable to apply a molding pressure exceeding 150 kg / cm ² , since the molding die bites. The molding speed may be the same as that of a normal cement product. It is preferable to maintain the pressure for about 10 seconds, and a high pressure of about 120 kg / cm ² may be initially applied in consideration of the above-mentioned pressure relaxation phenomenon. When performing vibration press molding instead of a simple press molding machine, a molding pressure of 5 to 40 kg / cm ² may be used.

Next, the press-formed body is pre-cured, and then autoclaved and solidified. Pre-curing
It is preferably carried out at 50 to 80 ° C for 7.5 to 20 hours, and the autoclave curing is preferably carried out at 120 to 190 ° C for 10 to 20 hours. In each case, the humidity is set to be as high as about 98%. As a result, the calcium component precipitated from fly ash such as coal ash by pre-curing reacts with the components of the cement to form a strong calcium silicate, which is converted into tobermorite by autoclave curing to obtain a solidified body having high bending strength and compressive strength. Can be

FIG. 2 is a graph showing the relationship between the press forming pressure and the strength of the solidified body. As shown in this graph, the compressive strength of the solidified body increases the press-forming pressure is high, because there is no further increase in the flexural strength exceeding 120 kg / cm ^2, actually exceeding 120 kg / cm ² There is no need to apply molding pressure.

[0012] In order to shorten the time required for curing the molded body, it is preferable to prepare a paste using hot water having the same temperature as that of the pre-curing. When warm water is used in this manner, the time required for the molded body to be heated to a temperature required for pre-curing can be reduced, and productivity can be improved.

The solidified body obtained as described above is crushed by a crusher to a particle size of 40 mm or less (C40) and becomes a roadbed material. This roadbed material is made from waste fly ash
Despite containing as much as 95%, it has sufficient strength to be used as roadbed material and crushed stone. In addition, press molding does not require a large number of molds such as cast molding, and can be molded with low moisture, so there is no need for a water reducing agent such as cast molding. It is economical because agents can be omitted. Hereinafter, examples of the present invention will be described.

[0014]

[Example] A mixture of 90% fly ash (coal ash) and 10% ordinary Portland cement 22% hot water at 60 ° C
Was mixed to prepare a fly ash slurry containing neither a water reducing agent nor a thickener. This slurry is filled into a mold,
Press molding was performed at a molding pressure of 100 kg / cm ² . The pressure holding time was 10 seconds, and the molded body was removed from the mold. The molded body was subjected to pre-curing at 98% humidity and 60 ° C. for 10 hours and autoclave curing at 98% humidity and 180 ° C. for 10 hours to obtain a solid. The compressive strength of the solidified body is 290 kg / cm ^2,
Flexural strength was 100 kg / cm ² . This was crushed by a crusher to obtain a roadbed material having a particle size of 40 mm or less (C40).

[0015]

As described above, according to the method for manufacturing a roadbed material of the present invention, it is possible to economically manufacture a roadbed material having a sufficient strength by using fly ash such as coal ash as a main component. As a result, the present invention is of high value as a new effective use of fly ash.

[Brief description of the drawings]

FIG. 1 is a flow sheet illustrating a process of the present invention.

FIG. 2 is a graph showing the relationship between press forming pressure and solidified body strength.

Claims (2)

[Claims] 1. 80 to 95% fly ash and 5 to cement
Water is externally added to a 20% mixture, and 15 to 25% of water is added. The obtained paste is press-molded, and the molded body is cured, solidified, and then crushed. Roadbed material used as a component, and a method for producing artificial crushed stone. 2. The method according to claim 1, wherein the press molding is performed at a pressure of 40 kg / cm ² or more.