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| Fine aggregate |
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Course aggregate |
Iron and steel slag aggregate is an industrial product that is manufactured under extensive quality management, and contains no organic impurities, clay, shells, or similar materials. For both fine particles and course particles, the chemical composition is completely uniform.
In addition, this aggregate contains no reactive silica, which is one cause of chemical reaction with alkali aggregates. It reduces environmental impacts, preserves precious natural resources needed to maintain ecosystems, and can reduce the energy that is consumed in mining, stone crushing, and other activities.
Course aggregate and fine aggregate |
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The two types of concrete aggregate that are manufactured using iron and steel slag as a raw material and which are covered by JIS standards are blast furnace slag aggregate and electric arc furnace oxidizing slag aggregate. Each of these types includes course aggregate and fine aggregate.
Course aggregate is a mechanically stabilized aggregate created by slowly cooling the molten slag after it is removed from a blast furnace or electric arc furnace.
Fine aggregate is a mechanically stabilized aggregate created by using water, air, or other means to rapidly cool the molten slag after it is removed from the furnace.
Recognized advantages |
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JIS standards were formulated for blast furnace slag course aggregates in 1977, and for fine aggregates in 1981. These standards have been incorporated into recommendations for a variety of practices by the Architectural Institute of Japan and the Japan Society of Civil Engineers, and these aggregates have earned a place as an important construction material. A JIS standard was also formulated for electric arc furnace oxidizing slag aggregates in 2003, and these also have been formulated into a design and practice recommendations by the Architectural Institute of Japan and the Japan Society of Civil Engineers.
Iron and steel slag aggregates have a number of advantages, including containing no organic impurities, clay, shells, or other substances that can affect concrete durability; little variation in quality; and no expansion due to alkali-aggregate reaction. In addition, the density of electric arc furnace oxidizing slag aggregate under oven-dry conditions is approximately 3.6 g/cm3, which is higher than other aggregates. This characteristic is put to use in applications such as radiation shielding concrete and heavy-weight concrete.
Contributing to environmental preservation as a replacement for natural aggregate |
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In recent years, with restrictions on dredging of marine sand and the stopping of sand imports from overseas, there has been a growing need in society for measures in response to the exhaustion of natural aggregate. This has resulted in a rapid increase in the amount of concrete slag aggregates that are sold. Blast furnace slag aggregates became a designated procurement item under the Green Purchasing Law in 2002, while electric arc furnace oxidizing slag aggregates were designated in 2005. These materials are highly regarded as environmental materials that can protect the environment by limiting exploitation of natural resources and reduce the amount of energy consumed in the mining of natural resources.
Example of use in interlocking blocks |
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| Nishidai Park (Kobe City) |
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