Recycling of fishery waste as planting base porous concrete aimed at achieving carbon neutrality

The Paris Agreement was adopted as the international framework against global warming, and the global movement to reduce greenhouse gas emissions is progressing.On the other hand, the final disposal amount will be reduced to 13 million tons in 2025 with considering the situationof waste disposal in Japan.Concrete, which is a typical recycled civil engineering material, is a very useful material for drastically reducing waste, while its constituent material, cement, emits a large amount of CO2in its manufacturing process.Additionally, due to the Japanese eating habits, a large amount of fishery waste including fish residues and shellfish are discharged. Although these are recycled, only about 30% of them are recycled.In this study, because the hydroxyapatite can contribute to reduction of the amount of cement and the plant growth promoted by phosphorus content, the hydroxyapatite produced from fish bones (Fishbone Powder:FbP), which is a fishery waste, is adopted as an alternative material to cement of planting base porous concrete. In addition, from the viewpoints of various physical properties (porosity, permeability and compressive strength), plant growth conditions and CO2emission reduction, the potential of recycling FbP as a binder for planting base porous concrete is also examined.As theresult, CO2emission of about 2.6 kg per 1 m3of porous concrete can be reduced by using FbP as a binder for planting base porous concrete. Additionally, the plant growth ability is also improved while the compressive strength is maintained above 10 N/mm2.