Humic matter as a challenge in deep soil mixing of soft organic soils
Humic matter as a challenge in deep soil mixing of soft organic soils
The stabilisation of soft organic soils poses significant geotechnical challenges due to their complex composition, low shear strength, and high compressibility. Conventional deep soil mixing techniques typically employ ordinary Portland cement as a binder. However, its effectiveness in organic-rich soils is limited due to adverse interactions between soluble humic matter and calcium ions, which hinder cement hydration and strength development. Furthermore, ordinary Portland cement has a significant ecological footprint, accounting for a large proportion of global carbon dioxide emissions. This study therefore focuses on the role of humic matter as a governing factor in the stabilisation of organic soils, as well as its differentiated chemical characterisation. A systematic analytical approach is employed that makes use of the pH-dependent solubility of humic fractions in order to enable their selective extraction and quantitative evaluation. Peat soils with a wide range of organic content and degrees of decomposition are investigated in various locations in Germany to capture the natural variability of humic matter. The study highlights the limitations of commonly applied bulk parameters for describing organic soils, demonstrating the importance of more detailed chemical characterisation in understanding soil-binder interactions. This approach provides a foundation for interpreting stabilisation behaviour and supports the development of more reliable and sustainable ground improvement strategies.
Michelle Bodner (Doebber); F. Rackwitz
International Conference on Advances and Innovations in Soft Soil Engineering (ICAISSE2026)
Ground Improvement and Low-Carbon Solutions
https://doi.org/10.53243/ICAISSE2026-34