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Author(s): Amr Aboulela, Matthieu Peyre-Lavigne, Cédric Patapy, Samuel Meulneyzer, Fabrizio Moro and Alexandra Bertron
Paper category: Proceedings
Book title: Proceedings of the Final Conference of RILEM 253-MCI Microorganisms-Cementitious Materials Interactions Volume II
Editor(s): Alexandra Bertron and Henk Jonkers
ISBN: 978-2-35158-207-7 (Set)
ISBN: 978-2-35158-210-7 (Volume 2)
e-ISBN: 978-2-35158-206-0
Publisher: RILEM Publications SARL
Publication year: 2018
Pages: 563-564
Total Pages: 308
Language : English

Abstract: Biodeterioration of cementitious materials in sewer networks is a major concern for health and economic reasons. It is essentially due to biological oxidation of H2S into H2SO4 leading to a local progressive dissolution of the cementitious matrix and the precipitation of expansive products likely to provoke cracks [1]. However, favorable environmental conditions and mostly water availability typically differ from one zone to another in the same concrete pipe. While the sewer crown is not always sufficiently wet, the tidal-zone undergoes successive cycles of wet-dry conditions [2]. These conditions lead to different levels of aggressiveness and hence there is a major stake in the design of durable and more economical cementitious materials, which could be achieved by combining both chemical and biological resistance adapted to the different zones. Mainly ordinary binders (OPC with/without slag) and CAC have been tested in these conditions. The better resistance of CAC is not well understood but it is generally assigned (without clear evidence) to the stability of the AH3 phase and to the inhibitory potential of aluminum on SOB activity [3-5]. Few data exist on the performance of alternative/innovative binders such as calcium sulfoaluminate cements and Portland cement mixed with different SCMs (slag, metakaolin, fly ash) although some of them are likely to be good candidates (high chemical stability with low calcium and high aluminum content). This research aims to develop resistant alternative materials and to understand their alteration mechanisms in sewer-like environments. Tests are performed in laboratory conditions using the BAC test, a biological test developed in Toulouse. Selection and culture of sulfur-oxidizing biofilm are operated at the surface of tested materials [6,7]. Leaching kinetics are evaluated by concentrations measurements in the leached solutions. Moreover, SEM-EDS-, XRD, EPMA and TGA analyses are used for the identification of the alteration mechanisms of the cementitious matrix.

Online publication : 2018
Publication type : full_text
Public price (Euros) : 0.00

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