Laboratory test to evaluate the resistance of cementitious materials to biodeterioration in sewer network conditions

The biodeterioration of cementitious materials in sewer networks has become a major economic, ecological, and public health issue. Establishing a suitable standardized test is essential if sustainable construction materials are to be developed and qualified for sewerage environments. Since purely chemical tests are proven to not be representative of the actual deterioration phenomena in real sewer conditions, a biological test–named the Biogenic Acid Concrete (BAC) test–was developed at the University of Toulouse to reproduce the biological reactions involved in the process of concrete biodeterioration in sewers. The test consists in trickling a solution containing a safe reduced sulfur source onto the surface of cementitious substrates previously covered with a high diversity microbial consortium. In these conditions, a sulfur-oxidizing metabolism naturally develops in the biofilm and leads to the production of biogenic sulfuric acid on the surface of the material. The representativeness of the test in terms of deterioration mechanisms has been validated in previous studies. A wide range of cementitious materials have been exposed to the biodeterioration test during half a decade. On the basis of this large database and the expertise gained, the purpose of this paper is (i) to propose a simple and robust performance criterion for the test (standardized leached calcium as a function of sulfate produced by the biofilm), and (ii) to demonstrate the repeatability, reproducibility, and discriminability of the test method. In only a 3-month period, the test was able to highlight the differences in the performances of common cement-based materials (CEM I, CEM III, and CEM V) and special calcium aluminate cement (CAC) binders with different nature of aggregates (natural silica and synthetic calcium aluminate). The proposed performance indicator (relative standardized leached calcium) allowed the materials to be classified according to their resistance to biogenic acid attack in sewer conditions. The repeatability of the test was confirmed using three different specimens of the same material within the same experiment and the reproducibility of the results was demonstrated by standardizing the results using a reference material from 5 different test campaigns. Furthermore, developing post-testing processing and calculation methods constituted a first step toward a standardized test protocol

Caractérisation du rôle de l'aluminium dans les interactions entre les microorganismes et les matériaux cimentaires dans le cadre des réseaux d'assainissement

An important part of the deterioration observed in concrete sewer networks is due to biological activity. In this context, calcium aluminate cement (CAC) based material has shown a better durability than ordinary Portland cement, usually used in such context. In literature, hypothesis explaining the better resistance are focused on aluminium. The aim of the project is to characterize the role of aluminium in the interactions between cementitious material and microorganisms. Reactor study and Lab scale aggressive biodeterioration protocol of cementitious material revealed that the better resistance of CAC is due to their lower reactivity and not to a bacteriostatic effect of the material on the microorganisms.Une part importante de la détérioration des réseaux d’assainissement en matériau cimentaire est d’origine biologique. Dans ce contexte, les matériaux à base de ciment alumineux ont montré une meilleure durabilité que ceux à base de ciment Portland ordinaire, couramment utilisés. Les hypothèses de la littérature qui expliqueraient cette meilleure résistance sont centré sur l’aluminium (présent à plus de 50% dans les ciments alumineux pour seulement 5% dans les ciments Portland). L’objectif de cette thèse est de caractériser et hiérarchiser les mécanismes de résistance des matériaux cimentaires lors de la biodétérioration. Cela permettra de comprendre le rôle de l’aluminium dans les interactions entre les microorganismes et les matériaux cimentaires. Après des études en réacteur et des tests de biodétérioration de pâte de ciments en laboratoire, il semblerait que la principale cause de résistance est due à la réactivité des matrices cimentaires plus qu’à un effet inhibiteur de l’aluminium ou du matériau sur les microorganismes

Characterization of the role of aluminium in the interactions between microorganisms and cementitious material in sewer networks context

Une part importante de la détérioration des réseaux d’assainissement en matériau cimentaire est d’origine biologique. Dans ce contexte, les matériaux à base de ciment alumineux ont montré une meilleure durabilité que ceux à base de ciment Portland ordinaire, couramment utilisés. Les hypothèses de la littérature qui expliqueraient cette meilleure résistance sont centré sur l’aluminium (présent à plus de 50% dans les ciments alumineux pour seulement 5% dans les ciments Portland). L’objectif de cette thèse est de caractériser et hiérarchiser les mécanismes de résistance des matériaux cimentaires lors de la biodétérioration. Cela permettra de comprendre le rôle de l’aluminium dans les interactions entre les microorganismes et les matériaux cimentaires. Après des études en réacteur et des tests de biodétérioration de pâte de ciments en laboratoire, il semblerait que la principale cause de résistance est due à la réactivité des matrices cimentaires plus qu’à un effet inhibiteur de l’aluminium ou du matériau sur les microorganismes.An important part of the deterioration observed in concrete sewer networks is due to biological activity. In this context, calcium aluminate cement (CAC) based material has shown a better durability than ordinary Portland cement, usually used in such context. In literature, hypothesis explaining the better resistance are focused on aluminium. The aim of the project is to characterize the role of aluminium in the interactions between cementitious material and microorganisms. Reactor study and Lab scale aggressive biodeterioration protocol of cementitious material revealed that the better resistance of CAC is due to their lower reactivity and not to a bacteriostatic effect of the material on the microorganisms

Pascal Häusermann et le motel L’Eau vive : une conception d’avant-garde ?

Built by Pascal Häusermann between 1967 and 1971 using the shotcrete shell technique, the Motel L’Eau Vive is a unique ensemble in Lorraine, located in the town of Raon-l’Étape. For the hotel, the Swiss architect applied his new conception of housing and town planning linked with prospective architecture and sculpture architecture. He designed an ensemble of nine hotel units, as well as the reception area and caretaker’s lodgings, in a natural setting. The motel evokes the excitement of the 1960s and the blossoming of a new architectural type linked with the development of tourism. This ensemble has been preserved and renovated by a group of devotees who wanted to bring the site back to life

Faculté de droit de Toulouse. Acte public pour la licence... : [Jus romanum : De Vulgari substitutione. - Code civil : minorité. - Code de procédure civile : Des Exceptions. - Code de commerce : Du Concordat.] / soutenu par M. Buvignier (Isidore-Eusèbe),...

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Resistance to biodeterioration of aluminium-rich binders in sewer network environment: Study of the possible bacteriostatic effect and role of phase reactivity

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Influence of dissolved aluminum concentration on sulfur-oxidizing bacterial activity in the biodeterioration of concrete

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