Biodeterioration of the Cement Composites

World Multidisciplinary Earth Sciences Symposium 2016

Luptáková, Alena^1 ; Etoková, Adriana^2 ; Maingová, Eva^1 ; Kovalíková, Martina^2 ; Jenárová, Jana^1

Slovak Academy of Sciences, Institute of Geotechnics, Watsonova 45, Koice

040 01, Slovakia^1

Technical University of Koice, Civil Engineering Faculty, Institute of Environmental Engineering, Vysokokolská 4, Koice

040 01, Slovakia^2

关键词: Acidithiobacillus thiooxidans;    Biological influences;    Calcium aluminate hydrate;    Chemical and biologicals;    Irreversible process;    Laboratory conditions;    Partial replacement;    Synthetic materials;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/44/5/052025/pdf
DOI  :  10.1088/1755-1315/44/5/052025

来源: IOP

【 摘 要 】

The destruction of natural and synthetic materials is the spontaneous and irreversible process of the elements cycling in nature. It can by accelerated or decelerated by physical, chemical and biological influences. Biological influences are represented by the influence of the vegetation and microorganisms (MO). The destruction of cement composites by different MO through the diverse mechanisms is entitled as the concrete biodeterioration. Several sulphur compounds and species of MO are involved in this complex process. Heterotrophic and chemolithotrophic bacteria together with fungi have all been found in samples of corroding cement composites. The MO involved in the process metabolise the presented sulphur compounds (hydrogen sulphide, elemental sulphur etc.) to sulphuric acid reacting with concrete. When sulphuric acid reacts with a concrete matrix, the first step involves a reaction between the acid and the calcium hydroxide forming calcium sulphate. This is subsequently hydrated to form gypsum, the appearance of which on the surface of concrete pipes takes the form of a white, mushy substance which has no cohesive properties. In the continuing attack, the gypsum would react with the calcium aluminate hydrate to form ettringite, an expansive product. The use supplementary cementing composite materials have been reported to improve the resistance of concrete to biodeterioration. The aim of this work was the study of the cement composites biodeterioration by the bacteria Acidithiobacillus thiooxidans. Experimental works were focused on the comparison of special cement composites and its resistance affected by the activities of used sulphur-oxidising bacteria. Cement composites contain partial replacement of binder by zeolite. All experiments were realised under the model laboratory conditions. The pH values and concentrations of Ca and Si in liquid phases were observed. From achieved experimental results it can be concluded, that concrete composites with partial binder replacement by zeolite are of the higher resistance against the biogenic sulphuric acid.