廃棄物を利用した生物易付着性コンクリートの開発と藻礁への応用―強度, 安全性, 生物易付着性に関する基礎的検討

It is possible that around 2030, the entire world will be facing a food crisis. Japan will have to cope with such a crisis using marine resources. In particular, since the fisheries environment in shallow seas offers high biological production, it is essential that the environment be maintained to an absolute high standard. However, in Japan, seaweed beds in shallow seas have been disappearing because of environmental destruction, water pollution, and so forth. Therefore, the development of environmental preservation and restoration of the seaweed beds in shallow seas are important Some of the reasons for environmental destruction are: Ocean dumping of fly ash and clinker ash, the waste from thermal power generations, and sand extraction and gavel extraction for aggregate from shallow areas.
This paper reports on the development of bio-adhesive waste-use-concrete using FA, CL, zeolite, which is waste from locally-established industry and waste molding sand containing Fe. If this material can be realized, conserving and restoring production environments in shallow seas and the recycling of waste would be feasible.
In the first experiment, the durability and the strength of five mortar test pieces were measured to form a seaweed bed. The five test pieces were Plain (normal mortar), FA & CL, FA & CL+zeolite, FA & CL+molding sand and FA & CL+zeolite+molding sand. In the second experiment, harmful materials, extracted from FA & CL mortar test pieces by elution test were investigated to examine their influence on the marine environment and marine life.
Furthermore, to investigate how well aquatic life can grow on the mortar test pieces, the mortar test pieces were immersed in seawater, and then biomass of biofilm was measured the quantity of ATP, chlorophyll a, and FDA decomposition activity.
The results of the first experiment showed that recycled waste-use-concrete containing FA, CL, molding sand and zeolite had sufficient strength for seaweed beds.
The results of the second experiment showed that the test pieces were also safe for seaweed beds since there was hardly any trace of heavy metals or organic phosphorus detected.
The results of last experiment were: (1) The quantity of ATP of three types of zeolite-molding sand system pieces (FA & CL+zeolite, FA & CL+molding sand and FA & CL+zeolite+ molding sand) was almost equal to the Plain or larger than the Plain.(2) The quantity of chlorophyll a was FA & CL+molding sand>FA & CL+zeolite > FA & CL+zeolite+ molding sand=FA & CL > Plain.(3) FAD decomposition activity was roughly the same as that of the Plain.
From these results, bio-adhesion to waste-use-concrete containing FA, CL molding sand as Fe and zeolite were satisfactory, and in particular, waste-use-concrete containing FA, CL and molding sand as Fe was algae flourished remarkably. Thus, it is feasible to use waste-use-concrete for artificial seaweed beds.