Mechanical and vegetative performance of ecological concrete with nutrient aggregates

Abstract

Enhancing its performance and maximizing the utilization of solid waste are pressing matters that require attention to guarantee the sustainable development of ecological concrete. This study focuses on the development of a nutrient-rich aggregate ecological concrete that demonstrates favorable plant growth performance through the utilization of recycled engineering muck and agricultural waste straw biochar. First, a unsintered nutrient aggregate is formulated through the combination of engineering muck, agricultural waste straw biochar, compound fertilizer powder, and super absorbent polymer with magnesium phosphate cement (MPC) and a hydrophilic polyurethane solution (HPS). Subsequently, by employing the prepared unsintered nutrient aggregates to partially substitute natural aggregates, a novel ecological concrete containing nutrient aggregates is generated. The study examines the impact of the composition of nutrient aggregates and porosity on the mechanical properties, water retention capacity, fertilization performance, and ecological attributes of concrete. The findings indicated that a combination of 17.06% MPC and 5.38% HPS proved to be the most effective curing method for nutrient aggregates at a liquid-solid ratio of 0.34. The water retention, fertility, and ecological performance of ecological concrete with nutrient aggregates improve with higher nutrient aggregate content, albeit at the expense of reduced mechanical performance. Under equivalent nutrient aggregate content, low porosity ecological concrete demonstrates higher fertility performance compared to high porosity ecological concrete, whereas the water retention performance shows the opposite trend. Furthermore, the patterns observed in phosphorus leaching concentration and conductivity suggest that the ecological concrete with nutrient aggregates exhibits a self-release characteristic of nutrients. The study can offer technical assistance for the efficient utilization of solid waste, thus advancing the sustainable growth of the ecological concrete industry.