Experimental study on the vegetation characteristics of biochar-modified vegetation concrete

[Display omitted] •In this paper, a new method for preparing biochar-modified vegetation concrete is presented.•The porosity, permeability and planting capacity of vegetation concrete were studied.•Different biochar contents have different effects on physical properties and planting capacity.•According to the growth of ryegrass, an optimal mix proportion of biochar-modified vegetation concrete was recommended. Vegetation concrete is an effective material to beautify the landscape, reduce pollution and protect the environment. To further improve the plant compatibility of vegetation concrete, this paper recommends an improved method of adding biochar particles to vegetation concrete. In this research, different masses of biochar were mixed into concrete to study the trend in porosity, permeability and plant compatibility. According to the growth status of three types of common grass species, ryegrass was selected as the best grass species in this study. As the content of biochar increased, the porosity and permeability coefficient of vegetation concrete continued to decrease, while the effect of biochar on plant growth promotion at first showed an increase to the maximum and then a gradual decrease. When the biochar content was 5 kg/m3, ryegrass showed the best growth. Compared with the experimental group of vegetation concrete without biochar, the plant height, root length and germination rate increased by 22.2%, 21.1% and 12%, respectively, on day 25, and the compressive strength also increased slightly. Therefore, adding a suitable amount of biochar can improve the characteristics of vegetation concrete. Furthermore, the optimum mix proportion of biochar-modified vegetation concrete was recommended.