| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥1,500,000 (Direct Cost: ¥1,500,000)
|
|---|
| Research Abstract |
Electric arc furnace oxidizing slag (EFO slag) which is produced as a by-product from the steel-making process is utilized as concrete aggregates. Until recent years, the slag has hardly been used as concrete aggregates because of expansion caused by the hydration of free lime and free magnesia included in the slag. However, improvements in the electric steel making process have been carried out, and application of the slag as concrete aggregate has been possible.
In this study, four types of EFO slag aggregates made in different cooling processes, i.e., air-granulated (rapidly cooled) slag, water-granulated (semi-rapidly cooled) slag, air-cooled (slowly cooled) slag, and improved slag (iron removed) are used. The chemical and mineralogical test results showed only a very small amount of f-CaO and f-MgO and did not detect unstable minerals.
The durability of slag concrete was investigated by the measurement of length change. Air-granulated EFO slag aggregate concrete does not expand. Wat
… More
er-granulated and air-cooled EFO slag aggregate concretes expand slightly, but the increase in the expansion became flat after about three years and flat until ten years. The expansion of the concrete stopped at about 0.034% or less.
The pre-cast concrete, paving concrete, heavyweight concrete, etc. were made. Cracks, popout or coloring were not observed on the surfaces of these actual concrete structures exposed in outdoor for 10-14 years.
The concrete and mortar specimens were exposed on the beach where the ocean waves on the coast were intense. The prism specimens were fixed in wave-dissipating concrete blocks on the beach for ten years. The deterioration of specimens was not recognized in the appearance and also in the strengths. Marine organisms such as shells and seaweed adhered to the slag concretes which were exposed on the beach. The adhesion of the marine organisms increased every year for ten years. It has been proven that noxious materials do not dissolve out from the concrete.
The durability of slag aggregate concrete was recognized, because satisfactory results were obtained in various tests for its use as a concrete aggregate. Less
|
