In the last two decades, study results that support microbe’s contribution to silica
precipitation are trickling in. Even a mechanism how amorphous silica biogenically
precipitated has been proposed using Shewanella oneidensis MR-1 as a model
organism [153]. Silicate modifying proteins of bacterial origin are also reported
[154]. These authors reported that a strain of Shewanella sp. isolated from a
hot-spring leaches silica and transforms it to Gehlenite which significantly improves
the concrete strength by filling the micropores. Moreover, unidentified microbe
affiliated to Thermoanaerobacter thermohydrosulfuricus produces bioremediase,
an enzyme with silica leaching activity. Both the isolated bioremediase and the
microbe were able to increase the compressional and tensile strength of cementitious
materials by more than 20% [155, 156]. The patent filed by Chattopadhyay and
Mandal [157] presents a very interesting result on the ability of the protein in
releasing silica. This may initiate further studies on microbial-based precipitation
of calcite for concrete application. Since there is a lot of silica in concrete, the
modification of the silica could be interesting in reconfiguring the structural integrity
of the concrete matrix.
3 Microorganisms in Concrete Application
The deterioration of concrete structures and its associated economic impact has
drawn a lot of attention in handling concrete degradation. A variety of methods
have been developed and used for maintenance of concrete structures. However,
these methods have limitations such as inefficiency and unsustainability, which
triggered the search for better ways of managing concrete degradation. In recent
years, the use of microorganisms to repair concrete cracks emerged as an attractive
alternative. Studies made so far revealed the advantages of using microorganisms in
the fight against deterioration of concrete. Microbially precipitated calcite has been
regraded as the most environmental friendly and economical material for repair or
protection of concrete. The use of microorganisms in the construction sector has
been broadly discussed in many reviews [18, 19, 57, 64, 158–161]. This chapter
provides an overview on the potential application of microorganisms in enhancing
the durability of concrete, specifically through their use in existing crack repair,
making protective surface coating, and self-healing concrete.
3.1 Microbes in Repairing Existing Concrete Cracks: Manual
Crack Fixing
The main reason of reduced durability of concrete structures is crack formation, a
phenomenon which makes easy path for water and dissolved aggressive substances
to the concrete structure. Thus, in concrete repair, it is mandatory to stop water
306
G. Mamo and B. Mattiasson
precipitation are trickling in. Even a mechanism how amorphous silica biogenically
precipitated has been proposed using Shewanella oneidensis MR-1 as a model
organism [153]. Silicate modifying proteins of bacterial origin are also reported
[154]. These authors reported that a strain of Shewanella sp. isolated from a
hot-spring leaches silica and transforms it to Gehlenite which significantly improves
the concrete strength by filling the micropores. Moreover, unidentified microbe
affiliated to Thermoanaerobacter thermohydrosulfuricus produces bioremediase,
an enzyme with silica leaching activity. Both the isolated bioremediase and the
microbe were able to increase the compressional and tensile strength of cementitious
materials by more than 20% [155, 156]. The patent filed by Chattopadhyay and
Mandal [157] presents a very interesting result on the ability of the protein in
releasing silica. This may initiate further studies on microbial-based precipitation
of calcite for concrete application. Since there is a lot of silica in concrete, the
modification of the silica could be interesting in reconfiguring the structural integrity
of the concrete matrix.
3 Microorganisms in Concrete Application
The deterioration of concrete structures and its associated economic impact has
drawn a lot of attention in handling concrete degradation. A variety of methods
have been developed and used for maintenance of concrete structures. However,
these methods have limitations such as inefficiency and unsustainability, which
triggered the search for better ways of managing concrete degradation. In recent
years, the use of microorganisms to repair concrete cracks emerged as an attractive
alternative. Studies made so far revealed the advantages of using microorganisms in
the fight against deterioration of concrete. Microbially precipitated calcite has been
regraded as the most environmental friendly and economical material for repair or
protection of concrete. The use of microorganisms in the construction sector has
been broadly discussed in many reviews [18, 19, 57, 64, 158–161]. This chapter
provides an overview on the potential application of microorganisms in enhancing
the durability of concrete, specifically through their use in existing crack repair,
making protective surface coating, and self-healing concrete.
3.1 Microbes in Repairing Existing Concrete Cracks: Manual
Crack Fixing
The main reason of reduced durability of concrete structures is crack formation, a
phenomenon which makes easy path for water and dissolved aggressive substances
to the concrete structure. Thus, in concrete repair, it is mandatory to stop water
306
G. Mamo and B. Mattiasson