Bacteria for Concrete Surface Treatment - Biotechnologies and Biomimetics for Civil Engineering - page 347

Fig. 15.4 Scanning electron micrographs of CaCO3 precipitation in the silica gel and PU foam.
a CaCO3 in silica gel (100x), b CaCO3 in silica gel (1000x), c CaCO3 in PU foam (100x), and
d CaCO3 in PU foam (1000x) (Wang et al. 2012a )
Although oxygen measurements indicate that bacteria were metabolically active in
the bio-based specimens, observed amounts of calcium carbonate precipitate did
not appear to substantially differ from control specimens. The reason for the
apparent uncoupling between metabolic activity and lack of enhanced calcium
carbonate precipitation can possibly be attributed to limited amounts of feed
applied and these remains to be clarified in pending studies (Guadalupe et al.
2014 ).
15.5 Conclusions
Some specific bacteria metabolic activities and deposition in concrete are
responsible to improve overall behaviors of concrete. Generally, it has been
hypothesized that almost all bacteria are capable of CaCO 3 production because
precipitation occurs as a byproduct of common metabolic processes such as