37º IAHS World Congress on Housing: - Universidad de Cantabria

XXXVII <strong>IAHS</strong><strong>World</strong> <strong>Congress</strong> on HousingOctober 26 – 29, 2010, Santander, SpainCODE: 130THE INVESTIGATION OF RESISTIBILITY OF CEMENTCOMPOSITES AGAINST BIOLOGICAL ACTIVITYEstokova, A. 1 , Ondrejka Harbulakova, V. 1 , Luptakova, A. 2 , Prascakova, M. 2 , Stevulova, N. 11 Institute of Building and Environmental EngineeringFaculty of Civil Engineering, Technical University of Kosice, Slovak Republice-mail: adriana.estokova@tuke.sk2 Institute of GeotechnicsSlovak Academy of Science, Slovak Republice-mail: luptakal@saske.skKey words: concrete, MIC, bacteria, biocorrosion, biodeterioration.AbstractThe role of bacteria causing the concrete deterioration has been linked to the generation ofbiogenic sulphuric and nitric acids resulting in corrosion process by dissolution of calciumcontaining minerals from the concrete matrices. The start and the course of corrosion areconditioned by many factors which undoubtedly include biological effects like the influenceof vegetation and microorganisms causing the so called microbial corrosion.This paper is primarily concerned with investigation of influence of sulphur-oxidisingbacteria Acidithiobacillus thiooxidans and sulphate-reducing bacteria Desulfovibriodesulfuricans at the resistance degree of cement composites. Cement composite samples with5 % addition of black coal fly ash as cement replacement as well as reference samples withoutcoal fly ash addition were investigated in experiments. The laboratory experiments as well asexperiments in situ in sewage system proceeded during 90 days.The penetration of the corrosion was manifested by surface changes and weight changes ofcement composites samples as well as changes in pH values. Considerable surface changeswere detected for all investigated samples by microscopic methods. The roughness increaseswere determined by confocal laser scanning microscopy. Crystals precipitated on concretesamples surface were identified by EDX as mixture of gypsum and ettringite.37º <strong>IAHS</strong> <strong>World</strong> <strong>Congress</strong> On Housing Science 77