Effect of bamboo biochar on the hydraulic conductivity of two different compacted soils

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Biochar is a carbon residue produced from the thermochemical decomposition of biomass. The inherent properties of biochar vary with the kinds of feedstock, heating rate and pyrolysis conditions. Consequently, the geotechnical properties of biochar-amended soil (BAS) were also found to differ with the types of biochar as per the past studies. However, the effect of bamboo biochar (BB) on the hydraulic conductivity of BAS was observed missing in the published literature. Hence the current research focuses on the influence of the amendment of BB on the hydraulic conductivity of low plastic clay (CL) and silty sand (SM) in compacted conditions. Samples were prepared using BB in 0%, 1%, 2%, 3.5%, and 5% proportions to the dry weight of the soils for experiments. The findings of this research showed that the biochar addition decreased the maximum dry density (MDD) and increased the optimum moisture content (OMC) of both soils. Moreover, falling head permeability test results showed that the hydraulic conductivity of CL soil mixed with BB decreased by 90% and 97% for 1% and 2% biochar content, respectively, and increased afterwards. In contrast to CL soil, a continuous increase in hydraulic conductivity was observed with an increase in biochar content for SM soil. The mean pore diameter (MPD) and surface morphology analysis confirmed that the biochar addition filled pore spaces in CL soil and created more voids in the SM soil, which led to a decrease and increase in hydraulic conductivity, respectively.

9th International Congress on Environmental Geotechnics (ICEG2023)

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