chloride mobility, has a great potential to emerge as an alternative approach in
making durable concrete. However, it is not yet out of the woods. There are critical
challenges that must be properly addressed to ensure the competitiveness of this
approach. One of the most important limitation is the high production cost. It is vital
to substantially cut down the production cost to enhance the applicability of this
technology among others through strain selection, use of cheap media, and efficient
and affordable cultivation-lyophilization and immobilization processes. For
instance, the production cost of axenic cultures and the subsequent encapsulation
is expensive; thus the use of non-axenic self-protected cultures may be the way
forward. However, the efficiency of the non-axenic self-protected cultures needs to
be further studied and proven. It should be noted that most of the studies reported are
done in a very ideal laboratory conditions which is different from the real concrete
environment. Thus, it is very difficult to expect a similar efficiency as achieved in
laboratories in in situ application. What is achieved can be considered as a remarkable proof of concept, but it needs more field trial studies to close the gap between
the laboratory ideal condition and the reality. It is delighting to see that a first step in
commercialization has been taken by the company Basilisk. Such steps will lead
forward to forge far efficient products that live up to its expectation.
Bacterial strains belonging to genus Bacillus are the gold standard microbes in
this area of applications. However, fungi and algae could also be of interest as their
use may offset some of the limitations related to bacterial applications. For example,
nutrient and precipitation precursor translocation could be a benefit of using fungal
strains. Moreover, the effort on developing biological agents for concrete application
is almost entirely focused on calcite precipitation. But it may be beneficial to look
other ways as well. One interesting approach could be silicate precipitation.
References
1. Van Tittelboom K, De Belie N (2013) Self-healing in cementitious materials – a review.
Materials (Basel) 6:2182–2217
2. De Muynck W, Cox K, De Belie N, Verstraete W (2008) Bacterial carbonate precipitation as
an alternative surface treatment for concrete. Constr Build Mater 22:875–885
3. De Muynck W, Debrouwer D, De Belie N, Verstraete W (2008) Bacterial carbonate precipitation improves the durability of cementitious materials. Cem Concr Res 38:1005–1014
4. Van Tittelboom K, de Belie N (2010) Self-healing concrete: suitability of different healing
agents. Int J 3R’s 1:12–21
5. Dhami N, Mukherjee A, Reddy MS (2012) Biofilm and microbial applications in
biomineralized concrete. In: Seto J (ed) Advanced topics in biomineralization. IntechOpen,
New York, pp 137–164. https://doi.org/10.5772/31124
6. Zhu T, Dittrich M (2016) Carbonate precipitation through microbial activities in natural
environment, and their potential in biotechnology: a review. Front Bioeng Biotechnol 4:1–21
7. Cailleux E, Pollet V (2009) Investigations on the development of self-healing properties in
protective coatings for concrete and repair mortars. In: Proceedings of 2nd international
conference on self-healing materials, Chicago, IL, 28 June–1 July
8. Alonso C, Andrade C, Rodriguez J, Diez JM (1998) Factors controlling cracking of concrete
affected by reinforcement corrosion. Mater Struct 31:435–441
Alkaliphiles: The Emerging Biological Tools Enhancing Concrete Durability
329
making durable concrete. However, it is not yet out of the woods. There are critical
challenges that must be properly addressed to ensure the competitiveness of this
approach. One of the most important limitation is the high production cost. It is vital
to substantially cut down the production cost to enhance the applicability of this
technology among others through strain selection, use of cheap media, and efficient
and affordable cultivation-lyophilization and immobilization processes. For
instance, the production cost of axenic cultures and the subsequent encapsulation
is expensive; thus the use of non-axenic self-protected cultures may be the way
forward. However, the efficiency of the non-axenic self-protected cultures needs to
be further studied and proven. It should be noted that most of the studies reported are
done in a very ideal laboratory conditions which is different from the real concrete
environment. Thus, it is very difficult to expect a similar efficiency as achieved in
laboratories in in situ application. What is achieved can be considered as a remarkable proof of concept, but it needs more field trial studies to close the gap between
the laboratory ideal condition and the reality. It is delighting to see that a first step in
commercialization has been taken by the company Basilisk. Such steps will lead
forward to forge far efficient products that live up to its expectation.
Bacterial strains belonging to genus Bacillus are the gold standard microbes in
this area of applications. However, fungi and algae could also be of interest as their
use may offset some of the limitations related to bacterial applications. For example,
nutrient and precipitation precursor translocation could be a benefit of using fungal
strains. Moreover, the effort on developing biological agents for concrete application
is almost entirely focused on calcite precipitation. But it may be beneficial to look
other ways as well. One interesting approach could be silicate precipitation.
References
1. Van Tittelboom K, De Belie N (2013) Self-healing in cementitious materials – a review.
Materials (Basel) 6:2182–2217
2. De Muynck W, Cox K, De Belie N, Verstraete W (2008) Bacterial carbonate precipitation as
an alternative surface treatment for concrete. Constr Build Mater 22:875–885
3. De Muynck W, Debrouwer D, De Belie N, Verstraete W (2008) Bacterial carbonate precipitation improves the durability of cementitious materials. Cem Concr Res 38:1005–1014
4. Van Tittelboom K, de Belie N (2010) Self-healing concrete: suitability of different healing
agents. Int J 3R’s 1:12–21
5. Dhami N, Mukherjee A, Reddy MS (2012) Biofilm and microbial applications in
biomineralized concrete. In: Seto J (ed) Advanced topics in biomineralization. IntechOpen,
New York, pp 137–164. https://doi.org/10.5772/31124
6. Zhu T, Dittrich M (2016) Carbonate precipitation through microbial activities in natural
environment, and their potential in biotechnology: a review. Front Bioeng Biotechnol 4:1–21
7. Cailleux E, Pollet V (2009) Investigations on the development of self-healing properties in
protective coatings for concrete and repair mortars. In: Proceedings of 2nd international
conference on self-healing materials, Chicago, IL, 28 June–1 July
8. Alonso C, Andrade C, Rodriguez J, Diez JM (1998) Factors controlling cracking of concrete
affected by reinforcement corrosion. Mater Struct 31:435–441
Alkaliphiles: The Emerging Biological Tools Enhancing Concrete Durability
329