Degradation modeling of concrete submitted to biogenic acid attack

Author(s): H. F. Yuan, P. Dangla, P. Chatellier
Paper category: Proceedings
Book title: Proceedings of the Seventh International Conference on Concrete under Severe Conditions – Environment and Loading
Editor(s): Z.J. Li, W. Sun, C.W. Miao, K.Sakai, O.E. Gjørv, N.Banthia
ISBN: 978-2-35158-124-7
e-ISBN: 978-2-35158-134-6
Publisher: RILEM Publications SARL
Publication year: 2013
Pages: 695-707
Total Pages: 13
Language : English

Abstract: Bio-deterioration of concrete, which is very common in sewer system and treatment plants, results in significant concrete degradation. Normally, the process can be described by two parts: Biochemistry reactions which produce sulfuric acid (H2SO4) from hydrogen sulfide oxidized by sulfur oxidizing bacteria (SOB) and chemical reactions between H2SO4 and cement hydration products which are responsible for concrete degradation.
A reactive transport model is proposed to simulate the bio-chemical and chemical degradation processes in cementitious materials contacting with SOB. To obtain the amount of biogenic H2SO4, the bio-oxidation of H2S by the activation of bacteria is simulated via a simplified model. The dissolution of portlandite (CH), the decalcification of calcium silicate hydrates (C-S-H) and the precipitation of gypsum (C S H2) are described by mass action law and threshold of ion activity products. To take into account the continuous decrease of the Ca/Si ratio during the dissolution of C-S-H a generalization of the mass action law is applied. A simplified damage model is introduced to characterize the change in microstructure due to the swelling of gypsum. The diffusion of ion is described via the Nernst-Plank equation. Experiments reported in literature are simulated. The numerical results and the experimental observations are compared and discussed.

Online publication : 2013
Publication type : full_text
Public price (Euros) : 0.00