Abstract
The article considers the change in the structural and phase composition of cement stone made of Portland cement of the CEM I 42.5 N brand in the process of bacterial and fungal corrosion during 6 months when humidified. The X-ray images of cement stone show peaks that characterize the non-hydrated components of Portland cement alite, belite, tricalcium aluminate, four-calcium aluminoferrite and gypsum. By the method of X-ray phase analysis, it is found that during microbiological corrosion, the content of all phases of cement stone decreases. The aspergillus niger van Tieghem fungi have a stronger effect on the structural and phase composition of cement stone. Fungal microorganisms destroy the crystalline phases and absorb amorphous phases – calcium hydrosilicates C-S-H (I) and C-S-H (II) and tobermorite. When bacteria Bacillus subtilis affects the cement stone, the content of the calcite phase increases, which is a product of corrosion, while the action of black mold reduces the intensity of CaCO3 peaks. A decrease in the content of low-base calcium hydrosilicates and ettringite, as well as other crystalline phases, leads to a decrease in the compressive strength of the cement stone. During 6 months of microbiological corrosion of cement concrete under conditions of constant wetting, the compressive strength decreases by about 35 %.
Highlights
The article considers the change in the structural and phase composition of cement stone made of Portland cement of the CEM I 42.5 N brand in the process of bacterial and fungal corrosion during 6 months when humidified
When bacteria Bacillus subtilis affects the cement stone, the content of the calcite phase increases, which is a product of corrosion, while the action of black mold reduces the intensity of CaCO3 peaks
20.Rumyantseva V.E., Konovalova V.S., Narmaniya B.E. Changes in the structural and phase composition and strength characteristics of concrete during liquid corrosion in chloride-containing media // Journal of Physics: Conference Series
Summary
ИЗМЕНЕНИЕ СТРУКТУРНО-ФАЗОВОГО СОСТАВА ЦЕМЕНТНОГО БЕТОНА ПРИ МИКРОБИОЛОГИЧЕСКОЙ КОРРОЗИИ. Что при микробиологической коррозии происходит снижение содержания всех фаз цементного камня. При воздействии на цементный камень бактерий Bacillus subtilis происходит увеличение содержание фазы кальцита, который является продуктом коррозии, в то время как действие черной плесени Aspergillus niger van Tieghem уменьшает интенсивность пиков CaCO3. Образующийся в результате бактериального воздействия во внутренних областях цементного камня, может вызывать внутренние напряжения, приводящие к растрескиванию и образованию локальных ям и трещин, что еще больше облегчает проникновение агрессивных веществ в бетон [16, 17]. При жидкостной коррозии цементного бетона в агрессивных средах снижается содержание фазы гидросиликата кальция, которая является носителем механической прочности [19, 20]
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