Enhancing grounding systems: effects of agro-based biochar used as backfill materials

Abstract

Agro-waste biochar is gradually emerging as a greener and effective means of enhancing the effectiveness of grounding systems. Yet, only a few of such wastes have been empirically assessed as ground enhancing materials. In this study, field-based soil resistivity and resistance to ground (RTG) value monitoring was used to assess the potential of biochar of coconut husk, sawdust, sugarcane bagasse, and rice husk as alternate ground enhancing materials vis-a-vis their susceptibility to seasonal variation and mode of application. The result of this study shows that the applied treatments exerted significant improvement (P-value≤0.05) in soil resistance and zone of influence values with the latter ranging less than 1 m for the clayey soil and equal of more than 2 m in the sandy soil. These effects of the study treatments were significantly influenced by time. A notable finding of this study is that rainfall and high moisture results in physical breakdown of biochar. This has significant implications for the use of treatment and the mode of application of treatment. Treatment, time, and mode of application of treatment played significant and interdependent role in reducing soil resistivity. These factors contributed to over 83% improvement of RTG values. This result suggests that though treatment, time and mode of application of treatment are major factors determining the effectiveness of ground enhancing materials, other confounding variables (e.g. method of carbonizing the waste, physical and chemical properties of the biochar) are also important determinants and must engender future research.

Graphical abstract