Research
Dr. Guijie Sang seeks to explore innovative grouting or healing techniques, including microbially induced carbonate precipitation (MICP), to enhance the hydromechanical properties of geomaterials such as soil, rock, and concrete. This research addresses a range of geo-environmental challenges, including soil instability, coastal erosion, leakage, and degradation of rock formations and wellbores during subsurface storage. It also focuses on enhancing the resilience of critical infrastructure for radioactive waste containment, including surface facilities for nuclear waste storage and geological disposal facilities (GDF).
Microbially induced carbonate precipitation (MICP)
The overarching goal of this research is to develop an industrially applicable bio-grouting technique for ground improvement. Guijie has collaborated with researchers from the University of Strathclyde (Glasgow) and the construction company BAM Ritchies to achieve this goal. His research began with understanding bacterial transport and attachment in saturated soil, monitoring and modeling hydraulic flow, delivering MICP fluids to the target treatment zone, and effectively transforming initially loose sand into 'sandstone' (unconfined compressive strength ~8 MPa). His work involved scaling up the MICP process from the centimeter-scale column experiments to the meter scale in the laboratory. He later supervised a field project with BAM Ritchies, applying MICP to improve natural soil deposits. Additionally, Dr Sang has collaborated with other industries and public bodies, including pharmaceutical company Nova Laboratory Limited on spray-drying storage of S. pasteurii for MICP applications (as Co-I); Scotland’s Industrial Biotechnology Innovation Centre (IBioIC) on optimising bacterial growth; and the British Geological Survey on in situ bio-stimulation techniques to protect coastal assets from hydraulic erosion. Guijie seeks to collaborate in the following areas:
• Fundemental MICP process (e.g. reactive transport modelling, micro-fluidic experiments)
• Geotechnical applications (e.g. slope stability, foundation reinforcement, erosion prevension)
• Self-healing materials for harsh environments (e.g. ionising radiation)
Rock Mechanics; Coupled Hydro-Mechanical-(Bio)Chemical Processes
Throughout Guijie's PhD at Pennsylvania State University, Guijie studied hydro-mechanical properties of subsurface rocks (e.g. shale) by investigating water transport and condensation in shale through analysis of sorption isotherms, transport modelling, and in situ small angle neutron scattering (SANS); detecting mechanical damage and failure of shale under cyclic uniaxial loading using in situ acoustic monitoring and coda wave interferometry; characterizing gas-sorption-induced rock swelling under reservoir condition; and quantifying rock-brine-CO2 interactions using SANS, and synchrotron X-ray computed tomography (CT). Guijie's research interests include:
• Rock Mechanics and Permeability
• Rock-fluid interactions (e.g. microbial activity on hydrogen consumption and its effect on rock properties)
• Geophysical and imaging techniques (Acoustic Emission, X-ray CT imaging, Electrical Resistivity Tomography)