Abstract
This paper is focused on the bacterial induced calcitation for the crack healing. The bacteria applied for this purpose are from group which is adapted for growth in the high pH environment as a concrete in hydration phase and their metabolic activity leads to create of calcite. In this study, three different bacteria strains (Sporosarcina pasteurii, Bacillus cohnii, Bacillus pseudofirmus) were applied and the influence of various temperatures on their microbial properties was investigated. Our previous experiment indicated that one of the applied bacterial strain in spores form (Bacillus pseudofirmus) are able to survive the temperatures in the range from -20 °C to 140 °C. The experiment described in this paper extends the previous study and determines the effect of different temperatures on the change in growth activity. In this experiment, bacterial activity was determined based on the change of absorbance in 640 nm by spectrophotometric measurements. The experiment was performed at optimal temperature (30 °C) and lower temperature (10 °C) and it used suitable broth for calcitation. The results showed that the beginning of metabolic activity was shifted by 40 to 50 hours. Only Bacillus cohnii showed different results because its metabolic activity was nearly zero at 10 °C.
Highlights
Concrete is the most used construction material worldwide
The bacteria applied for this purpose are from group which is adapted for growth in the high pH environment as a concrete in hydration phase and their metabolic activity leads to create of calcite
The bacteria Bacillus pseudofirmus (Figure 1) had a longer log phase at the lower temperature but the optical density was similar in 145 hours of experiment
Summary
Concrete is the most used construction material worldwide. Degradation of this material is known and described phenomena. The main degradation processes are caused by pollutants present in the atmosphere such as oxides of nitrogen, carbon, sulphur, acids and many other compounds. These processes are known as atmospheric corrosion or chemical degradation. Many types of repair systems are available These epoxy-based fillers or silane-based water repellent systems may have only short-term effectiveness or a negative impact on the environment. Today it focuses more on instant repair or self-healing of cracks may extend the service-life of concrete structures [2]
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