JP2002179451A - Concrete or mortar using slag aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide concrete or mortar in which expansion-inhibited steelmaking slag, is used as aggregate and which is produced with similar mix proportions to those of normal concrete and capable of being placed with similar placing work to that of normal concrete and has various kinds of performance such as durability with respect to freezing and thawing action, equivalent to those of normal concrete. SOLUTION: Aggregate containing steelmaking slag and water-granulated blast-furnace slag in a 20-70 mass % ratio of the water-granulated blast-furnace slag to the mass of the steel making slag, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to concrete or mortar, and more particularly to concrete or mortar, in which steelmaking slag, whose effective use has been hindered by expansion and collapse, is reliably mixed with granulated blast furnace slag to suppress expansion and collapse. And concrete or mortar used as an aggregate conforming to the aggregate particle size range specified by JIS.

[0002]

2. Description of the Related Art Blast furnace slag has been specified in JIS as a concrete or mortar material. However, steelmaking slag cannot be used as a concrete or mortar material due to problems such as expansion and collapse. . Therefore, Japanese Patent Application Laid-Open No. 10-152364 discloses that one or two of the silica-containing substance having latent hydraulic property and the silica-containing substance having pozzolanic reactivity are used as cement 5 or less.
A method is described in which the content of 0% or more suppresses the expansion and collapse of steelmaking slag, and is used as a hydrated solid such as concrete or mortar.

Japanese Patent Application Laid-Open No. 10-287454 discloses that 14 to 400 parts by volume of coal ash or 100 parts by volume of steelmaking slag or 100 parts by volume of steelmaking slag and 100 parts by volume of steelmaking slag, 10 to 400 parts by volume, and coal ash 1 having a total of silica and alumina of 80% or more
A method is described in which a fine aggregate is used as concrete or mortar or the like, which is characterized by comprising 0 to 600 parts by volume.

[0004] All of the above-mentioned technologies are based on the fact that unreacted CaO, which is an expansion factor of steelmaking slag, is hydrated and remarkably expands in volume. This is to suppress volume expansion by causing a pozzolanic reaction between unreacted CaO and a pozzolanic substance such as silica or alumina eluted from coal ash containing silica and alumina. The pozzolanic reaction means that pozzolans (silica or fine silica and alumina powders) combine at room temperature in the presence of calcium hydroxide and water to form an insoluble compound.

[0005] The handling of substances that suppress the expansion of steelmaking slag is different in the above two publications.
According to Japanese Patent No. 364, the silica-containing substance having latent hydraulic property and the silica-containing substance having pozzolanic reactivity are as follows.
In addition to the fine powder of m2 / g, the silica-containing substance having pozzolan reactivity is also in the form of powder such as fly ash or silica fume. Therefore, these materials that suppress the expansion of steelmaking slag are treated as admixtures for cement. , As a binder. However, in this method, a silica-containing substance having latent hydraulic properties and a silica-containing substance having pozzolanic reactivity, which is a material that suppresses the expansion and collapse of steelmaking slag, are to be blended in a certain ratio into steelmaking slag used as aggregate. It will be difficult. That is, there is a problem in that it is difficult to guarantee reliable suppression of expansion of the steelmaking slag.

On the other hand, in Japanese Patent Application Laid-Open No. 10-287454, coal ash having a total of silica and alumina of 80% or more is treated as the same fine aggregate as steelmaking slag, thereby suppressing the expansion of steelmaking slag. The substance to be performed (coal ash in which the total of silica and alumina is 80% or more) is to be blended at a fixed ratio. However, cement, which is the binder, and coal ash, which is a part of the fine aggregate, are powdered, so that the concrete becomes powdery as a whole, and when mixing concrete,
Approximate values of the fine aggregate ratio, the unit coarse aggregate volume, and the unit water amount obtained in general concrete cannot be used, and it is necessary to find a unique composition. In particular, the unit water volume tends to increase. In addition, an increase in the amount of powder causes an increase in the viscosity of the concrete, making it difficult for fine air bubbles to enter, deteriorating the consistency (the property of concrete that has not yet solidified as indicated by the degree of softness) and decreasing the durability against freeze-thaw action. In addition to the fact that the fly ash is pozzolan and that fine air does not enter, breathing (water is separated and rises after concrete is poured and floats on the upper surface of concrete) ) Is extremely reduced, making the surface finish of concrete difficult.

[0007]

Since steelmaking slag is rich in iron, it is used as a soil improvement material for paddy fields.
It has a large amount of lime, silicic acid, and formic acid, so it is used as an improver for acidic soil. Since steelmaking slag contains phosphoric acid, it also plays a role as a fertilizer as well as soil improvement.

However, such an effective use is only about 1% of the amount of steelmaking slag generated, and at present, most of the steelmaking slag is used for low-grade applications such as temporary materials in civil engineering works. This is because steelmaking slag is generated in the steelmaking process, and compared with the fact that the blast furnace slag generated in the ironmaking process is very homogeneous, there is a problem that the steelmaking slag quality differs with different steel types, and above all, This is because steelmaking slag contains free lime and the slag itself expands and collapses due to its hydration reaction.

[0009] In view of the above background, effective utilization of steelmaking slag is strongly desired. Accordingly, the present invention relates to a technique for suppressing expansion and collapse of steelmaking slag and making it available as concrete aggregate. However, steelmaking slag is used as an aggregate by reliably suppressing expansion, and can be mixed and cast in the same way as ordinary concrete, and its performance such as durability against freeze-thaw action is equal to or higher than ordinary concrete, or The technology for providing mortar has not yet been disclosed.

The present invention has been made to solve such a problem, and uses a mixture of steelmaking slag and granulated blast furnace slag as an aggregate, and uses free CaO, which is an expansion factor of steelmaking slag, as blast furnace water. An object of the present invention is to provide concrete and mortar by replacing a crushed slag with a hydraulic reaction material.

[0011]

The above object is achieved by concrete or mortar using steelmaking slag and aggregate containing granulated blast furnace slag in an amount of 20% by mass to 70% by mass of the steelmaking slag. Is done. As a result of investigations made by the present inventors to achieve the above object, when steelmaking slag is used as aggregate of concrete or mortar, granulated blast furnace slag equivalent to 20% by mass or more and 70% by mass or less of steelmaking slag is used as fine aggregate. It has been newly found that the addition can prevent breakage of hardened concrete or mortar due to expansion and collapse of steelmaking slag.

As long as the above relationship between the amount of steelmaking slag and the amount of granulated blast furnace slag is satisfied, fine aggregate contains blast furnace slow cooling slag,
Electric furnace slag processed to prevent powdering and collapse by ferronickel slag, copper slag, and slag generator,
One or a combination of two or more of sand, crushed sand, and artificial lightweight aggregate can be mixed.
One or a combination of two or more of gravel, crushed stone, and artificial lightweight aggregate can be mixed. When steelmaking slag is used only for fine aggregate, granulated blast furnace slag is mixed only with fine aggregate due to the particle size.Therefore, it is necessary to use these aggregates for the entire amount of coarse aggregate. Become. Among these aggregates, preferred are blast furnace slow cooling slags that lead to resource saving and utilization of blast furnace slag generated in large quantities.

The steelmaking slag used to solve the problem preferably has a water immersion expansion ratio of more than 0% to 3.0% or less.
The water immersion expansion ratio is a value measured in accordance with the method for water immersion expansion test of steel slag specified in JIS A 5015: 1992 Appendix 2. The reason for setting it to 3.0% or less is that when the upper limit of the water immersion expansion ratio at which the aggregate can be used is confirmed by an experiment, the expansion ratio of the steelmaking slag used is 3.0%, This is because it is not possible to determine whether the aggregate can be used.

A steelmaking slag having a high water immersion expansion ratio needs to have an immersion expansion ratio of 3.0% or less in advance by an aging treatment. Aging treatment methods include natural aging and steam aging, either of which may be used. The granulated blast furnace slag used to solve the problem has a particle size of 0.
It is 15 mm or more and 5 mm or less. In practice, 0.1
It is assumed that 85% or more is retained in a 5 mm sieve, and that the 5 mm sieve is 85% or more in weight, and an allowable range of 15% is observed. If the thickness is less than 0.15 mm, the viscosity of the concrete that has not yet set increases due to the increase in the amount of powder in the concrete or mortar, and the workability (the property of the concrete that has not yet set as indicated by the degree of ease of driving) deteriorates. There is a concern that durability may decrease due to an increase in the unit water content in the concrete mix. Also, 5
The reason why the diameter is not more than 5 mm is that no particles having a particle diameter of more than 5 mm are manufactured at present. If a change in the manufacturing process results in a particle size of more than 5 mm, it seems that it can be used.

Granulated blast furnace slag is 70% by mass of steelmaking slag
The following is to ensure the usage of steelmaking slag. The reason why the content is set to 20% by mass or more is that concrete was produced at a mixing ratio of less than 20% by mass, and as a result, the concrete was broken without being able to completely suppress the expansion and collapse of the steelmaking slag. Blast furnace slag is a component of iron ore melted in a blast furnace that manufactures pig iron, in which components other than iron are separated and recovered together with limestone as an auxiliary material and ash in coke.
It has components similar to natural rock. The slag that has just been taken out of the blast furnace is in a molten state at about 1,500 ° C., but becomes a slow cooling slag (slow cooling process) and a granulated slag (rapid cooling process) depending on the cooling method. Each of the properties is characterized in that the gradually cooled slag is a crystalline rocky slag, whereas the granulated slag is turned into a vitreous (amorphous) granular slag by rapid cooling.

[0016] The steelmaking slag is generated in the steelmaking process of removing unnecessary components from hard and brittle pig iron produced in a blast furnace to produce steel having toughness and workability. Concrete refers to a material obtained by kneading cement, water, fine aggregate, coarse aggregate and, if necessary, an admixture and integrating them. The mortar lacks coarse aggregate in concrete.

The fine aggregate passes through a 5 mm mesh sieve (a sieve opening of 4.76 mm), and the coarse aggregate stays on the 5 mm mesh sieve. The fine aggregate is 10 mm in order to avoid practical inconvenience. All the sieves pass through a 5 mm sieve at 85% or more by weight, and coarse aggregates remain at 85% or more by weight in a 5 mm sieve, and an allowable range of 15% is set.

Based on this finding, granulated blast furnace slag having the same particle size as fine aggregate can be used as a material for suppressing the expansion and collapse of steelmaking slag. The steelmaking slag and the expansion / collapse suppressing material can be used in the same aggregate, so that the expansion of the steelmaking slag can be ensured without impairing the workability of concrete.・ Concrete mixing can be easily performed while maintaining the amount of expansion / collapse suppressing material (blast furnace granulated slag) capable of suppressing collapse.

The reason that granulated blast furnace slag having a particle size of 0.15 mm or more and 5 mm or less suppresses expansion and collapse of steelmaking slag is that granulated blast furnace slag is hydraulically hardened by alkali stimulation of steelmaking slag and cement. when water is a substance contributing to hard quicklime (CaO), silica (SiO ₂₎ and of alumina (Al ₂ 0 _3), and the lack of quick lime content than the content of silica and alumina, the It is considered that this is because free CaO, which is an expansion factor in the steelmaking slag, is removed to supplement quicklime.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Concrete or mortar cement, coarse, comprising using a steelmaking slag according to the present invention and an aggregate containing granulated blast furnace slag in an amount of 20% by mass to 70% by mass of the steelmaking slag. The ratio of aggregate, fine aggregate and water may be determined in the same manner as in the case of ordinary concrete.

As the steelmaking slag, converter slag, hot metal pretreatment slag, and electric furnace slag can be used. As the granulated blast furnace slag, granulation before the furnace and granulation outside the furnace can be used, and the particle size thereof is 0.15 mm or more and 5 mm or less.
If a particle size smaller than this is used, the amount of powder increases as compared with the standard particle size of JIS and the Japan Society of Civil Engineers, which not only increases the unit water volume at the time of mixing the concrete, but also impairs workability. In order to avoid this, it is desirable that the fine aggregate made by mixing steelmaking slag and granulated blast furnace slag conforms to the particle size of the blast furnace slag fine aggregate specified in JIS A 5011.

As the cement, besides ordinary Portland cement, various mixed cements may be used. To improve the properties of the concrete or mortar that has not yet set, or of the hardened concrete or mortar, admixtures commonly used in concrete may be added.

The concrete kneading method, the casting / forming method, and the curing may be the same as those of ordinary concrete. When promoting the expansion of steelmaking slag and investigating the long-term durability of concrete or mortar, it is necessary to perform curing in a constant temperature water bath at 100 ° C or lower, preferably 80 ° C. This is because the curing temperature is too high in autoclave curing, which is a general method for promoting the expansion of steelmaking slag, and the sulfur content of the granulated blast furnace slag changes to hydrogen sulfide. When hydrogen sulfide is generated, the mortar portion is deteriorated even if it does not cause cracking or breakage of the concrete, and the strength is significantly reduced. Therefore, it is not possible to quantitatively grasp the strength reduction due to minute expansion of the steelmaking slag. Also, 80 ° C
Since it is the same as the curing temperature of the water immersion expansion test specified in JIS A 5015 Annex 2, it can be compared with the water immersion expansion test result of only steelmaking slag used as aggregate, There is also an advantage that the expansion suppression effect can be quantitatively grasped.

However, since the generation of hydrogen sulfide does not lead to the destruction, it is considered that the autoclave curing may be used for examining only the presence or absence of the destruction in a short time and conducting a simple expansion suppression effect. The inventors used autoclave curing with a steelmaking slag having an extremely small expansion ratio (water immersion expansion ratio was 0.04% (the expansion ratio did not increase after the second day of water immersion and became a constant value). As a result, it was confirmed that concrete after autoclaving would be destroyed unless granulated slag was used as the material for suppressing expansion and collapse.Thus, it was confirmed that autoclave curing did not overlook even a certain degree of expansion of steelmaking slag. It seems possible.

[0025]

EXAMPLE A steelmaking slag (hot metal pre-treatment slag) and a granulated blast furnace slag having a natural aging treatment and a long-term water immersion expansion ratio (30-day water immersion) of 5 mm under particle diameter of 3.0%,
Then, the coarse aggregate and the fine aggregate obtained by mixing the blast furnace slag were kneaded with ordinary Portland cement, water, and coarse aggregate (blast furnace slag gradually cooled material) to produce concrete. Concrete was prepared based on the reference composition shown in Table 1 by changing the mixing ratio of steelmaking slag, granulated blast furnace slag, and slowly cooled blast furnace slag in the aggregate as shown in Table 2.

The concrete slump is 12c.
m, and the amount of air was 4.5%. After the concrete is made, JI
In addition to performing a compression test after curing in water based on SA 1108, a compression test was performed after curing in water at 80 ° C. to promote expansion of steelmaking slag, and the quality of concrete was confirmed. The reason why the curing time in water at 80 ° C. was set to 30 days was that, as a result of the water immersion expansion test of the steelmaking slag, the expansion stopped in 30 days, and it was determined that the curing time in 30 days was sufficient.

[0027]

[Table 1]

[0028]

[Table 2]

In the formulations 1 and 2 used as comparative examples, the amount of granulated blast furnace slag was insufficient, and if the expansion of the steelmaking slag was accelerated by curing in water at 80 ° C., concrete was destroyed, and the compressive strength could not be measured. Was. In contrast, Examples 3 and 2
As shown in FIG. 0, when the amount of granulated blast furnace slag is set to 20% by mass or more with respect to the steelmaking slag in the aggregate, in addition to the strength corresponding to the water cement ratio being developed in the underwater curing on the 28th,
Even when the expansion of the steelmaking slag was accelerated by curing in water at 80 ° C., the concrete did not break.

[0030]

Industrial Applicability According to the present invention, it is possible to use steel slag which is desired to be effectively used for all aggregates of concrete and mortar. Further, particularly effective use of steel slag is strongly desired. Steelmaking slag can also be used. Moreover, it was not possible in the past,
This makes it possible to reliably suppress the expansion of the steelmaking slag and to use it as an aggregate, and to prepare concrete or mortar that can be blended and poured with the same feeling as ordinary concrete.

Further, since the expansion and collapse of the steelmaking slag is suppressed by the hydraulic reaction of the granulated blast furnace slag used as the same aggregate, a higher compressive strength than that of ordinary concrete can be obtained. If concrete is mixed in consideration of this compressive strength, economical concrete mixing with a reduced amount of cement is possible, and if you just want to obtain solidified, solidified material without using cement at all There is also the possibility of making.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C04B 111: 32 C04B 111: 32 111: 76 111: 76 (72) Inventor Shigeo Kobayashi Futtsu-shi, Chiba 20-1 Shintomi Nippon Steel Corporation Technology Development Headquarters (72) Inventor Yoshihiro Takano 20-1 Shintomi Futtsu-shi, Chiba Prefecture Nippon Steel Corporation Technology Development Headquarters F-term (reference) 4G012 PA29 PC12 PC12 PC13 PE01

Claims (13)

[Claims] 1. A concrete or mortar comprising fine granulated blast furnace slag and steelmaking slag as fine aggregate. 2. Concrete or mortar characterized by including granulated blast furnace slag, steelmaking slag, and slowly cooled blast furnace slag as fine aggregate. 3. A concrete or mortar comprising steelmaking slag as coarse aggregate and granulated blast furnace slag as fine aggregate. 4. A concrete or mortar containing steelmaking slag as coarse aggregate and granulated blast furnace slag and steelmaking slag as fine aggregate. 5. A concrete or mortar comprising steelmaking slag as coarse aggregate and granulated blast furnace slag and slowly cooled blast furnace slag as fine aggregate. 6. A concrete or mortar comprising steelmaking slag as coarse aggregate and granulated blast furnace slag, steelmaking slag and blast furnace slow cooling slag as fine aggregate. 7. A concrete or mortar characterized by containing steelmaking slag and blast furnace slowly cooled slag as coarse aggregate and granulated blast furnace slag as fine aggregate. 8. A concrete or mortar characterized by containing steelmaking slag and blast furnace slow cooling slag as coarse aggregate, and blast furnace granulated slag and steelmaking slag as fine aggregate. 9. A concrete or mortar comprising a steelmaking slag and a blast furnace slow cooling slag as coarse aggregate and a blast furnace granulated slag and blast furnace slow cooling slag as fine aggregate. 10. A concrete or mortar characterized by containing steelmaking slag and blast furnace slow cooling slag as coarse aggregate and blast furnace granulated slag, steelmaking slag and blast furnace slow cooling slag as fine aggregate. 11. The granulated blast furnace slag has a particle size of 0.1%.
The concrete or mortar according to any one of claims 1 to 10, wherein 85% or more of the 5 mm sieve stays in the 5 mm sieve, and the 5 mm sieve holds 85% or more in weight. 12. The amount of granulated blast furnace slag used is 20% by mass with respect to steelmaking slag used for fine aggregate and coarse aggregate.
The concrete or mortar according to claim 1, wherein the content is at least 70% by mass. 13. The immersion expansion ratio of the steelmaking slag is 0%.
The concrete or mortar according to any one of claims 1 to 12, wherein the content is from super to 3.0% or less.