Abstract:
While awareness around the environmental impact of existing grout materials and chemical binders is
increasing rapidly, biotechnologies are growing traction as sustainable alternatives in groundwork
operations. Herein we present the principles and application methods of bio-grouting. The term is used to
describe a system which is based on soil, groundwater or marine enzymes which are able to catalyze the
production of calcite replicating a natural phenomenon. The system’s end result are mineral crystalline
bridges which act as binders to improve the geotechnical properties of soils. This paper presents a
comprehensive description of bio-grouts, their underlaying mechanisms contributing to mineralization as
well as environmental considerations. With their water-like rheology, bio-grouts have a wide application
range and are minimally invasive, requiring only very limited injection pressures. The equipment is the
same as that used in conventional cement grouting, and the reactant components are worldwide available
or easily suppliable, which explains why bio-grouting has nowadays become a valuable and sustainable
alternative towards efficient soil treatment. Recent developments in the last years have allowed to further
increase the applicability and efficiency of bio-grouts to ultimately bridge the gap between research and
practice. A case study is illustrated in this paper showing the successful implementation of bio-grout for
the stabilization of weakly cemented sandstone to safeguard an adjacent road segment in Switzerland