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Purpose <p>This study evaluates the feasibility of constructed Technosols (CT) prepared solely from concrete recycled aggregates (CRAs) as a plant growth medium, aiming to eliminate the need for organic amendments and avoid potential challenges such as substrate shrinkage and the complex formulation of multiple ingredients to fulfill soil functions. The study examines whether such substrates can support plant growth and sustain microbial activity and, if so, whether plant–microbe activity can induce weathering of the CT.</p> Materials and methods <p>Five CT were laboratory-prepared by blending CRAs of two size fractions (&lt; 0.05&#xa0;mm and 0.05–2&#xa0;mm) at different mass ratios. After preparation, the physicochemical properties, namely bulk density, total porosity, particle-size distribution, water-holding capacity (WHC), pH, organic carbon, electrical conductivity, and available nutrients were assessed. Enzyme activities were measured using an enzyme-linked immunosorbent assay kit. Plant growth tests were conducted in an artificial climate chamber under controlled conditions using tall fescue (<i>Festuca arundinacea</i>) over a 45-d period, with natural topsoil (CK) used as the control. Following plant harvest, the microbial community composition was analyzed via 16&#xa0;S rRNA gene sequencing and mineralogical and microstructural changes were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.</p> Results and discussion <p>The CRAs-based CT exhibited alkaline conditions and lower macronutrient contents (N, P, and K) but significantly higher micronutrient availability (S, Fe, Mn, Zn, and Cu) than CK. Enzyme activities associated with macronutrient cycling decreased, whereas peroxidase activity increased, suggesting an adaptive response to the lower WHC of the substrate compared to CK. The 45-d plant growth experiment showed successful plant establishment in CT, with germination trends, root length, shoot length, and root dry weight similar to those observed in CK. These results suggest that the CT can function as a plant growth substrate during early developmental stages without the addition of auxiliary organic amendments. Following plant establishment, the CT showed enrichment of bacterial genera and microbial biomarkers along with detectable mineralogical and surface morphological changes, suggesting the initiation of substrate weathering.</p> Conclusions <p>This 45-day laboratory study demonstrates that CT composed entirely of CRAs can support early plant establishment and microbial communities that contribute to substrate weathering. These findings suggest the potential of such a medium as a simple and circular strategy for construction waste reuse in urban greening applications. However, its long-term ecological functionality requires validation through field studies before any recommendations for extensive use.</p>

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Feasibility of the constructed Technosols prepared solely from concrete recycled aggregates as a plant growth medium

  • 期刊论文

  • 发表日期：

    2026年3月21日

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  • Fengrui Zi,
  • Qun Zhao,
  • Haiyan Chen,
  • Zhangqian Wu,
  • Wenxing Li,
  • Haoran Song,
  • Jianhong Huang,
  • Jie Li,
  • Xuewei Hu,
  • Senlin Tian

摘要

Purpose

This study evaluates the feasibility of constructed Technosols (CT) prepared solely from concrete recycled aggregates (CRAs) as a plant growth medium, aiming to eliminate the need for organic amendments and avoid potential challenges such as substrate shrinkage and the complex formulation of multiple ingredients to fulfill soil functions. The study examines whether such substrates can support plant growth and sustain microbial activity and, if so, whether plant–microbe activity can induce weathering of the CT.

Materials and methods

Five CT were laboratory-prepared by blending CRAs of two size fractions (< 0.05 mm and 0.05–2 mm) at different mass ratios. After preparation, the physicochemical properties, namely bulk density, total porosity, particle-size distribution, water-holding capacity (WHC), pH, organic carbon, electrical conductivity, and available nutrients were assessed. Enzyme activities were measured using an enzyme-linked immunosorbent assay kit. Plant growth tests were conducted in an artificial climate chamber under controlled conditions using tall fescue (Festuca arundinacea) over a 45-d period, with natural topsoil (CK) used as the control. Following plant harvest, the microbial community composition was analyzed via 16 S rRNA gene sequencing and mineralogical and microstructural changes were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.

Results and discussion

The CRAs-based CT exhibited alkaline conditions and lower macronutrient contents (N, P, and K) but significantly higher micronutrient availability (S, Fe, Mn, Zn, and Cu) than CK. Enzyme activities associated with macronutrient cycling decreased, whereas peroxidase activity increased, suggesting an adaptive response to the lower WHC of the substrate compared to CK. The 45-d plant growth experiment showed successful plant establishment in CT, with germination trends, root length, shoot length, and root dry weight similar to those observed in CK. These results suggest that the CT can function as a plant growth substrate during early developmental stages without the addition of auxiliary organic amendments. Following plant establishment, the CT showed enrichment of bacterial genera and microbial biomarkers along with detectable mineralogical and surface morphological changes, suggesting the initiation of substrate weathering.

Conclusions

This 45-day laboratory study demonstrates that CT composed entirely of CRAs can support early plant establishment and microbial communities that contribute to substrate weathering. These findings suggest the potential of such a medium as a simple and circular strategy for construction waste reuse in urban greening applications. However, its long-term ecological functionality requires validation through field studies before any recommendations for extensive use.