PROBLEM TO BE SOLVED: To provide a hydrated solidified body for underwater installation, which has a high seaweed deposition, stably functions as a seaweed deposition base for a long period of time, and efficiently and stably supplies seaweeds with a nutrient. SOLUTION: The hydrated solidified body is obtained by hydrating and hardening a raw material comprising a granular steel slag as a main aggregate and blast furnace slag fine powder as a main binder and contains a nitrogen-containing organic substance as a part of the raw material. The hydrated solidified body exhibits high functions as the seaweed deposition base of (i) stable elution and supply of a nitrogen content, an iron content (ferrous iron), Si, P etc., being important seaweed nutrients, (ii) increased seaweed deposition properties since the surface of the hydrated solidified body becomes an environment suitable for seaweed deposition, and (iii) accordingly direct supply of seaweeds with eluted nutrients. COPYRIGHT: (C)2009,JPO&INPIT
