2. Biological process induced calcium
carbonate precipitation
Currently, techniques for ground improvement are
being explored which aim at enhancing soil properties
on demand by stimulating natural bio-chemical
processes in- situ [1-6]. One of these technologies is
biocementation (or biocalcification), an in-situ soil
strengthening technique involving microbial-induced
CaCO3 precipitation. Several studies have shown that
this process can be used to improve the mechanical
properties of porous materials [1-3, 5-9]. In most of
these studies, CaCO3 precipitation was induced by
hydrolysis of urea in a solution with calcium chloride
(CaCl2). Purified urease enzymes or whole bacterial
cells, containing the enzyme in high concentrations,