Abstract
We developed high-density and hard concrete using seawater and/or unwashed sea sand. The internal organizations of that concrete was denser compared with normal concrete, and it was clear that the water-tightness, early strength, and long-term strength of seawater and unwashed sea sand concrete were increased. Reinforced concrete structures that used a non-corrosive reinforcing bar were durable in the long term. Seawater and unwashed sea sand concrete construction could be used on remote islands or on the coast to reduce CO2 emission and construction costs. This paper describes the properties of s seawater and unwashed sea sand concrete and the examination about application to the concrete structures
