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Biodétérioration des ciments Portland et sulfoalumineux dans les réseaux d’assainissement urbains

Abstract : Traditional cements contain Portland clinker, which causes high greenhouse gas emissions. For this reason, new more environmentally friendly cements, such as sulpho-aluminous cements, are being developed. This study investigates the biodegradation process of two of these cements (CSA B and CSA F), in comparison with two Portland clinker-based cements (CEM I and CEM III). Pastes of these four cement grades with the same initial porosity, as well as mortars, were exposed at four different sites in the Nancy agglomeration's sewage network. These samples were monitored and characterised (physico-chemical properties, surface mineralogy) at regular intervals for 18 months. The environmental conditions (temperature, precipitation) of the agglomeration were also recorded during this period.A direct sulphuric acid attack test carried out on the 4 cement grades enabled the majority of gypsum to be detected on their surface. It was found that gypsum was the main degradation product obtained for both Portland clinker cements and CSA. The analysis of the surfaces of the samples taken from the sites revealed the characteristic elements of the first phases of biodeterioration: deposition of sulphur, formation of gypsum and ettringite. Bacterial colonisation thus appears from the first months of exposure of the samples on all sites. Nevertheless, some sites show much higher densities, especially when seasonal environmental conditions are optimal (humidity and temperature), and the presence of H₂S favourable to bacterial development is likely. In this context, sulphur and then gypsum in particular appear on the surface of the samples. The iron-rich CSA is the least bioreceptive, apparently due to the appearance of gibbsite on the surface, which acts as a buffer to inhibit bacterial succession.
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Submitted on : Monday, November 8, 2021 - 9:46:08 AM
Last modification on : Tuesday, November 9, 2021 - 4:05:12 AM

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  • HAL Id : tel-03418738, version 1

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Awa Yasmina Faridha Sawadogo. Biodétérioration des ciments Portland et sulfoalumineux dans les réseaux d’assainissement urbains. Matériaux. Université de Lorraine, 2021. Français. ⟨NNT : 2021LORR0146⟩. ⟨tel-03418738⟩

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