Exploring implication of variation in biochar production on geotechnical properties of soil

Abstract

Biochar produced from the pyrolysis of plant based feedstock has been advocated as an alternative soil amendment for landfill cover. Previous literature indicated that the pyrolysis temperature influences the intra-pore distribution and surface functional groups (especially hydroxyl groups), resulting in "love-hate relationship" of the biochar amended soil (BAS) with water. From the purview of geotechnical engineering, the effect of pyrolysis temperature on geotechnical properties are rarely investigated. In total, three biochar rates (0, 5 and 10%) were considered for a set of geotechnical experiments in sand clay mixture soil with biochar produced at 350 ℃ and 550 ℃ . Test results show that biochar addition in soil, in general regardless of pyrolysis temperature, increased the optimum moisture content (OMC), plasticity index, soil water retention characteristics (SWRC) and decreased the maximum dry density (MDD), shear strength parameters (cohesion, friction), erosion rates. Whilst comparing the pyrolysis temperature effects on two biochar amended soils, only marginal effects (in terms of magnitude) on SWRC were observed. The most significant decrease of MDD (or increase of OMC) for 5% (w/w) and 10% (w/w) biochar additions occurred at pyrolysis temperatures of 550 ℃ and 350 ℃, respectively. In addition, biochar produced at lower pyrolysis temperature (350 0 C) was more effective in reducing cracks and enhancing shrinkage area ratio. 10% biochar addition with pyrolysis temperature of 350 0 C was the optimum combination in resisting soil erosion. The study provides evidence that the geotechnical properties of biochar amended soils for landfill cover soil applications could be tailor made by controlling the pyrolysis temperature.

Expansive soil-biochar-root-water-bacteria interaction: Investigation on crack development, water management and plant growth in green infrastructure

“…Considering balance of yield and material performance aforementioned, tested biochar in the study was produced at moderate temperature (i.e., 500 °C) for 1.5 hours. Geotechnical properties of biochar amended soils could be tailor made via changing the pyrolysis temperature (Ganesan et al., 2020; Wani et al., 2020). More intra-pore and less hydroxyl groups are observed in biochar pyrolyzed at 550 °C as compared to 350 °C (Ganesan et al., 2020).…”

“…Geotechnical properties of biochar amended soils could be tailor made via changing the pyrolysis temperature (Ganesan et al., 2020; Wani et al., 2020). More intra-pore and less hydroxyl groups are observed in biochar pyrolyzed at 550 °C as compared to 350 °C (Ganesan et al., 2020). According to Bordoloi et al.…”

Exploring Efficiency of Biochar in Enhancing Water Retention in Soils with Varying Grain Size Distributions using ANN Technique

“…Further, the effect of biochar on WHC may vary with the type of feedstock, from which biochar was produced [2,36]. Biochars produced from plant feedstock types tend to have higher porosity than that of animal feedstock [36][37][38]. As far as authors are aware, there is a lack of systematic study that investigates the extent of biochar effect on WHC of soils with varying grain size distribution.…”

Impacto del biocarbón en el suelo agrícola

“…Cabe resaltar que el tamaño de la partícula del biocarbón varía dependiendo de la temperatura de transformación. Las partículas de biocarbón más finas corresponden a temperaturas altas (550 °C), las cuales aumentan las áreas de superficie específicas y reducen la gravedad específica del suelo compuesto [40].…”

“…Igualmente, Ganesan et al [40] demostraron que las curvas de retención de agua de un suelo con adición de biocarbón muestran una mejor respuesta en comparación con un suelo desnudo. Estos autores evaluaron la densidad seca máxima y el contenido de humedad óptimo para un suelo desnudo, que fueron de 17 kN/m³ y 17,2 %, respectivamente.…”