Degradation modeling of concrete submitted to biogenic acid attack

摘要: Bio-deterioration of concrete, which is very common in sewer system and waste water treatment plant, results significant structure degradation. Normally, the process can be described by two following parts: 1) Biochemistry reactions producing biogenic aggressive species biofilms are spread on surface concrete. As one most acid pipes, sulfuric (H2SO4) produced sulfur oxidizing bacteria (SOB). 2) Chemical between cement hydration products responsible for concrete deterioration. A reactive transport model proposed to simulate bio-chemical chemical deterioration processes cementitious materials contact with SOB H2S or solution. This aims at solving simultaneously biochemistry/chemistry a global coupled approach. To provide an appropriate environment grow, neutralization (i.e., absorption aqueous corrosion) considered. obtain amount H2SO4, bio-oxidation activation simulated via simplified model. suitable abiotic pH reduction introduced. The production rate H2SO4 governed content gas.It assumed that all thermodynamical equilibrium. dissolution portlandite (CH) calcium silicate hydrates (C-S-H) precipitation gypsum (C¯S H2) sulfide mass action law threshold ion activity products. take into account continuous decrease Ca/Si ratio during C-S-H generalization applied. By simplifying gypsum, damage introduced characterize due swelling gypsum. Thus, porosity evolution depth taken account. Only diffusion Different coefficients employed various ions Nernst-Planck equation was implemented. effect microstructure change properties considered as well. For both materials, balance equations total each atom (Ca, Si, S, K, Cl) used couple (bio-)chemical reactions. implemented within finite-volume code, Bil. Following introduction principle finite volume method, coupling bio-chemistry chemistry illustrated. this model, some experiments reported literature, including immersion tests (statical solution condition flow condition) microbiological simulation tests, simulated. numerical experimental observations compared discussed. influence (initial porosity, carbonated layer, etc.) environmental factors (concentration H2S, investigated Furthermore, long term predictionis conducted