JPH0551907A - Manufacture of composite roadbed material - Google Patents

Abstract

PURPOSE:To increase the compressive strength of roadbed by a method in which blast-furnace granulated slag formed from melted blast-furnace slag at a given temperature by flowing is mixed with gradually cooled blast-furnace slag in a given proportion. CONSTITUTION:A blast-furnace granulated slag is obtained by a method in which melted slag from blast furnace is received in a melted slag pan through an inclined trough, sent to a slag-manufacturing equipment, and blown under conditions of about 138 deg.C slag temperature, about 50 deg.C water temperature, about 3kg/cm<2> flow pressure, and water/slag ratio of about 10. The slag (3-20 pts.wt.) is well-brained to a max. grain size of 30mm or less and mixed with gradually cooled blast-furnace slag (97-80 pts.wt.). The monoaxial compressive strength and corrected CBR value can thus be increased, and the porosity of the slag can be lessened to reduce production of yellow water.

Description

Detailed Description of the Invention

[001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace slag roadbed material having high strength.

[002]

BACKGROUND ART Blast furnace slag is used for roads and roadbeds. This blast furnace slag is obtained by smelting molten blast furnace slag, sprinkling it with water, and crushing it to a maximum particle size of 30 mm or less. Blast furnace slowly cooled slag. When this slag is used as a roadbed material, a strong roadbed is formed due to the latent hydraulic property peculiar to slag, and therefore there is an advantage that even if the upper layer of the roadbed is covered with asphalt concrete, cracks and ruts do not occur.

However, when the blast furnace slowly cooled slag is exposed to rainwater, sulfur ions are eluted from the slag to generate yellow water, which causes a problem in appearance when temporarily stored outdoors before construction. In particular, this yellow water continues to be generated until the amount of sulfur that can be eluted in the slag is reduced, so it was necessary to prevent it completely before shipping.

As a method for preventing this yellow water from being generated before shipment, (1) pile up slag with a particle size adjusted to a height of about 5 m, cut the piles at intervals of several weeks, and repeat transshipment for a long period of time. Method of oxidizing sulfur by exposure to wind and rain, (2) Method of blowing steam into piled slag and increasing temperature to promote elution and oxidation of sulfur, (3) Molten slag in molten slag A method of adding an oxidizer at the stage of a gutter or a ladle to promote the oxidation of sulfur, and (4) 1000-1100 slag with a controlled particle size.
Methods such as heating to ℃ have been proposed, but (2) ~
Since the method (4) has an economical problem, the inexpensive method (1) is adopted.

[0095]

However, when the blast furnace slowly cooled slag is exposed to the atmosphere for a long period of time, due to the development of hydraulic property, the fine particles having a fine particle size are combined and hardened, and the particle size becomes large and the particle size distribution changes. As a result, the uniaxial compressive strength and the corrected CBR value, which are quality assurance values for the roadbed material, are reduced. The present invention provides a method for manufacturing a composite roadbed material that improves deterioration of the quality assurance value of the roadbed material.

[0096]

According to the present invention, molten blast furnace slag is blown at a temperature of 1380 ° C. or less to produce granulated blast furnace slag, and 3 to 20 parts of the granulated slag is mixed with a maximum particle size of 30 mm.
A compound roadbed material was manufactured by mixing 97 to 80 parts of crushed and sized blast furnace slowly cooled slag.

[0097]

When the molten blast furnace slag is blown at a temperature of 1380 ° C. or less, the particle size distribution of the granulated blast furnace slag obtained is smaller than that of the slowly cooled blast furnace slag. Therefore, if this slag is blended with blast furnace slow-cooled slag having a large particle size distribution due to long-term atmospheric exposure, the particle size distribution becomes smaller, and the uniaxial compressive strength of the roadbed material and the modified CBR value increase. In addition, since the number of pores is small, yellow water is less likely to be eluted and the generation of yellow water can be reduced.

Even if the granulated blast furnace slag to be blended with the slowly cooled blast furnace slag is blended at a temperature higher than 1380 ° C., the uniaxial compressive strength of the roadbed material and the corrected CBR value do not increase. This is because when the temperature during blowing is higher than 1380 ° C., the number of pores increases and the slag specific gravity and unit volume weight decrease, so the impact force of the road roller and rammer during roadbed compression and This is because the load cannot be absorbed and the compression cannot be performed precisely, and the uniaxial compressive strength and the corrected CBR value are rather reduced.

The blended amount of granulated blast furnace slag is 2
If you add more than 0 parts, it will be out of the specified particle size distribution range,
If the desired uniaxial compressive strength or modified CBR value is not achieved and the amount is less than 3 parts, the effect of improving these characteristics is small and the occurrence of yellow water cannot be reduced.

The production of granulated blast furnace slag compounded in the present invention is as follows.
The molten slag discharged from the blast furnace is received by a slag ladle via a tilting gutter and conveyed to an out-furnace water granulation production facility, where the slag temperature is set to 138
It may be blown at 0 ° C or lower. Slag temperature is 1380
If it is higher than ℃, immerse the steel ingot in the slag pan,
Try to lower the slag temperature. It should be noted that when the slag temperature is 1280 ° C. or lower, the viscosity rapidly increases and the slag does not flow out of the slag ladle. As the blowing conditions, the temperature of water is preferably 50 ° C. or lower, the blowing pressure is 3 Kg / cm ² or more, and the water / slag ratio is 10
This is all you need to do.

[0111]

[Example] A molten blast furnace slag having a temperature of 1350 ° C., a water temperature of 55 ° C.,
Blast furnace granulated slag produced under the conditions of blow pressure of 4.5 Kg / cm ² and water / slag ratio of 13 was crushed and sized, and then exposed to the atmosphere for 60 days, and then blended with the slowly cooled blast furnace slag to elute sulfur. Granulated slag compounding amounts of 3 parts, 10 parts and 20 parts of roadbed materials were produced.

As a comparative example, the granulated slag before furnace prepared by producing molten blast furnace slag at 1480 ° C. under the same blowing conditions as described above was crushed and sized, and then exposed to the atmosphere for 60 days to elute sulfur, thereby slowly cooling the blast furnace. To prepare a roadbed material with 20 parts of the granulated slag before the furnace. Table 1 shows the physical properties of blast furnace slowly cooled slag, granulated blast furnace slag and granulated slag before furnace, Table 2 the particle size distribution of granulated blast furnace and granulated slag before furnace, and Table 3 further. The particle size distribution of the roadbed material of the blast furnace slow-cooled slag alone and the particle size distribution of the roadbed material in which the blast-furnace slow-cooled slag is mixed with the blast-furnace granulated slag or the pre-furnace granulated slag are shown.

[0113]

[Table 1]

[0142]

[Table 2]

[0115]

[Table 3] (Note) Example 1 Blast furnace slowly cooled slag / Blast furnace granulated slag = 80/2
0 Example 2 Blast furnace slowly cooled slag / Blast furnace granulated slag = 90/1
0 Example 3 Blast furnace slowly cooled slag / Blast furnace granulated slag = 97/3 Comparative example 1 Blast furnace slowly cooled slag alone Comparative example 2 Blast furnace slowly cooled slag / Pre-furnace water granulated slag = 80/2
0

Further, a roadbed test of each of these roadbed materials was conducted by JI.
The results carried out based on S A 5015 (1985) are shown in Tables 4 and 5.

[0172]

[Table 4]

The

[Table 5]

[0119]

As described above, according to the method for producing a roadbed material of the present invention, it is possible to increase the uniaxial compressive strength and the corrected CBR value of the roadbed material, which was insufficient by the blast furnace slow cooling slag alone. , Can reduce the generation of yellow water.

Claims (1)

[Claims] 1. A molten blast furnace slag is blown at a temperature of 1380 ° C. or lower to produce granulated blast furnace slag, and the granulated slag 3
A method for producing a composite roadbed material, characterized in that ˜20 parts are blended with 97 to 80 parts of blast furnace slowly cooled slag crushed and sized to a maximum particle size of 30 mm or less.