Field investigation of cementitious materials durability in sewer environment

Author(s): T. Pons, M. Gueguen, A. Grandclerc, I. Nour, C. Fourdrin, Y. Pechaud, M. Peyre Lavigne, C. Patapy, E. Paul, A. Bertron and T. Chaussadent
Paper category: Proceedings
Book title: Proceedings of the Final Conference of RILEM 253-MCI Microorganisms-Cementitious Materials Interactions Volume I
Editor(s): Alexandra Bertron and Henk Jonkers
ISBN: 978-2-35158-207-7 (Set)
ISBN: 978-2-35158-209-1 (Volume1)
e-ISBN: 978-2-35158-206-0
Publisher: RILEM Publications SARL
Publication year: 2018
Pages: 127-135
Total Pages: 288
Language : English

Abstract: Biodeterioration of cementitious materials in sewers systems occurs in some local conditions where H2S is produced and stripped in the gas phase. In these local conditions, H2S is oxidized by chemical and biological reactions into sulfuric acid. This acid production leads to the dissolution of the reactive phases and the precipitation of secondary expansive compounds as Gypsum and Ettringite.
Since several decades, some field experiments were operated to understand and qualify the durability of different binders based on Ordinary Portland Cement (OPC) and Calcium Aluminate Cement (CAC) in such environments. However, few data were collected, especially for different type of binders. This study focused on 3 mortars (under cylinder form) based on OPC and CAC, exposed on 3 different sites with contrasted physic-chemical conditions (labelled S1, S2, S3). The mortars were exposed for 734 days. The mean H2S values were 6.3, 15.8 and 5.5 ppm for S1, S2 and S3 respectively. The biodeteriorated samples were analysed regularly (every 4 or 6 months) by visual observations, surface pH measurements, masses and diameters evolutions. For the mortars exposed on S2, the most deteriorated, mortars cylinders were sampled at days 566 and 734 for deeper analysis by SEM (EDS) and XRD.
Gypsum was observed on all materials. The analysis confirmed the higher durability of CAC materials in such environment with a lower decalcification than for OPC based materials, and the formation of an aluminium phase at the surface. The field experiments are still running. During the next year further investigations will be performed on the exposed mortars, including other binder types.

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

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