Among the techniques for converting stacked coal gangue to reusable material, one of the most effective ways is to use coal gangue as a coarse aggregate in green concrete productions. The physical and chemical properties of rock and spontaneous-combustion coal gangue are generally suitable for being used as a coarse aggregate in green concrete. Coal gangue concrete is not recommended to be used in subsurface structures, as its water absorption law would be changed under a large replacement ratio. The mechanical performance of coal gangue concrete is degraded by raising the replacement ratio. Over-low and -high concrete grades are not suggested to be used as coal gangue aggregate, unless extra admixtures or specific methods are used. The influence of coal gangue on the durability of coal gangue concrete is remarkable, resulting from the porous structure of coal gangue that provides more transmission channels for air and liquid in concrete, but is beneficial for thermal insulation. The usage of coal gangue in structural concrete members is still limited. The mechanical behavior of some structural members using coal gangue concrete has been reported. Among them, concrete filled steel tubes are a preferable configuration for using coal gangue concrete, regarding both the mechanical and durability performance.

The application of agricultural and aquaculture waste in concrete greatly reduces the pressure on the ecological environment brought by traditional concrete production. The use of agricultural and aquaculture wastes as cement replacement, aggregate replacement and fiber reinforcement has showed great potential. Making full use of these wastes can help the development of sustainable concrete. This paper provides an objective evaluation and summary of agricultural waste and aquaculture waste in green concrete. Agricultural waste is divided into natural plant fiber, agricultural waste ash and multi-application waste according to useful function and alternative methods, such as sisal fiber, olive waste ash, and bamboo. Aquaculture waste mainly refers to some shells such as oyster shell. This paper analyzes the advantages and disadvantages of agricultural and aquaculture waste concrete applications that have been reported and shows how different agricultural and aquaculture wastes are made in concrete. The selection of appropriate treatment methods and usage scenarios is extremely important for agricultural and aquaculture waste concrete, which can determine whether the concrete has reliable performance. This paper will lay a foundation for the progress of waste concrete and provide reliable help for the development of environmental protection concrete.