Abstract
Important deteriorations have been observed in concrete sewers, due to hydrogen sulfide (H2S) presence. H2S is used as nutrients for sulfur-oxidizing bacteria (bacteria able to oxidize the reduced sulfur compounds) and is oxidized into sulfuric acid. This acid attack of concrete leads to cementitious matrix dissolution and expansive products formation (gypsum and ettringite). This phenomenon disturbs the sewer system and conducts to expensive works of rehabilitation. In order to avoid this degradation, a French project named “FUI Duranet” was initiated to propose more efficient solutions. The aim of this thesis is to define a representative and accelerated test as well as a predictive model.Abiotic tests allow stating that this first stage of the biodeterioration mechanisms is not the limiting stage. Indeed, the adapted surface pH of the cementitious materials to bacteria development is quickly reached with a high H2S concentration (100 ppm), whatever the cementitious materials considered (mortars based on CEM I, CEM III, CEM IV, CEM V, CAC, and SSC cements). The chemical-transport modeling of the sulfuric acid attack of cementitious materials and the establishment of a representative and accelerated test have been proposed to predict their service life in these conditions. For the test, different seeding technics have been compared in order to determine which one lead to the better reproduction and acceleration of biodeterioration mechanisms. This test allows recommending the sludge use, which contains a microorganism’s consortium, rather than a collection strain use, whose activity is too dependent on environmental conditions. With the experimental test and the model, the better resistance of the calcium aluminate cement and the important degradation of the Portland cements are quickly confirmed, as highlighted during the field tests