Keywords Alkaliphiles, Bioconstruction, Biodeposition, Biomineralization,
Calcite, Cement, Concrete, Construction biotechnology, Crack repair,
Extremophiles, Self-healing, Silicate
Abbreviations
ABC
ATP-binding cassette
ACDC
Activated compact denitrifying core
BCM
Biologically controlled mineralization
BIM
Biologically induced mineralization
CERUP Cyclic EnRiched Ureolytic Powder
EPS
Extracellular polymeric substances
MICCP Microbial-induced calcium carbonate precipitation
PCB
Polychlorinated biphenyl
RH
Relative humidity
1 Introduction
Among all materials ever used in construction, concrete has a unique combination of
desirable properties. It is cheap, easy to cast, resistant to fire, exhibits enormous
compressional strength, and its raw materials are relatively abundant. These make
concrete one of the most common and indispensable building materials that the
world has seen. A wide variety of constructions such as residential and commercial
buildings, roads, dams, bridges, railways, airports, and subways use concrete.
Although concrete has high compressional strength, its tensile strength is relatively
low, and hence it is usually reinforced with high tensile strength materials such as
steel [1]. Reinforced concrete is used widely because of its strength, durability, price,
and beauty. However, due to its inherent property (heterogeneity) and non-favorable
environments (such as earthquake and high external loads), even reinforced concrete
structures are subject to a deterioration phenomenon known as cracking. If the cracks
remain open, the concrete will be degraded and the steel corrode, which lead to an
eventual collapse of the structure. Thus, if the service time of the concrete structure
must be extended, cracks should be repaired.
Over the years, different concrete crack repair methods have been developed.
Once the presence of crack is identified and repair is a necessity, the crack repair
agent will be applied either topically or injected into the crack. The topical method
applies fixing agents such as epoxy and cementitious or caulk product on top of the
crack. Although this contributes to the appearance and to some extent slows down
the cracking process, it will not last long before the crack transmits itself through the
seal and the deterioration resumes. The other method of application involves injection of epoxy, polyurea, urethane, sand, silica fillers, or another repair agent into the
Alkaliphiles: The Emerging Biological Tools Enhancing Concrete Durability
295
Calcite, Cement, Concrete, Construction biotechnology, Crack repair,
Extremophiles, Self-healing, Silicate
Abbreviations
ABC
ATP-binding cassette
ACDC
Activated compact denitrifying core
BCM
Biologically controlled mineralization
BIM
Biologically induced mineralization
CERUP Cyclic EnRiched Ureolytic Powder
EPS
Extracellular polymeric substances
MICCP Microbial-induced calcium carbonate precipitation
PCB
Polychlorinated biphenyl
RH
Relative humidity
1 Introduction
Among all materials ever used in construction, concrete has a unique combination of
desirable properties. It is cheap, easy to cast, resistant to fire, exhibits enormous
compressional strength, and its raw materials are relatively abundant. These make
concrete one of the most common and indispensable building materials that the
world has seen. A wide variety of constructions such as residential and commercial
buildings, roads, dams, bridges, railways, airports, and subways use concrete.
Although concrete has high compressional strength, its tensile strength is relatively
low, and hence it is usually reinforced with high tensile strength materials such as
steel [1]. Reinforced concrete is used widely because of its strength, durability, price,
and beauty. However, due to its inherent property (heterogeneity) and non-favorable
environments (such as earthquake and high external loads), even reinforced concrete
structures are subject to a deterioration phenomenon known as cracking. If the cracks
remain open, the concrete will be degraded and the steel corrode, which lead to an
eventual collapse of the structure. Thus, if the service time of the concrete structure
must be extended, cracks should be repaired.
Over the years, different concrete crack repair methods have been developed.
Once the presence of crack is identified and repair is a necessity, the crack repair
agent will be applied either topically or injected into the crack. The topical method
applies fixing agents such as epoxy and cementitious or caulk product on top of the
crack. Although this contributes to the appearance and to some extent slows down
the cracking process, it will not last long before the crack transmits itself through the
seal and the deterioration resumes. The other method of application involves injection of epoxy, polyurea, urethane, sand, silica fillers, or another repair agent into the
Alkaliphiles: The Emerging Biological Tools Enhancing Concrete Durability
295