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Author(s): Virginie Wiktor, Henk Jonkers, Alexandra Bertron
Book Title: International RILEM Conference on Microorganisms-Cementitious Materials Interactions
Editors: Virginie Wiktor, Henk Jonkers, Alexandra Bertron
e-ISBN: 978-2-35158-160-5
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: XVII
Total Pages: 1
Language: English

Abstract: Infrastructures and buildings are exposed to microorganisms in a variety of contexts.
Structures exposed to aggressive aqueous media containing microorganisms (waste water, soft water, fresh water, ground water, sea water, agricultural or agro-industrial environments), often concrete structures, can suffer deterioration that can be detrimental (loss of alkalinity, erosion, spalling of the concrete skin, corrosion of rebars, loss of water- or airtightness…). The deleterious effect of microorganisms, mainly bacteria and fungi, on the cementitious matrix has been found to be linked, on the one hand, with the production of aggressive metabolites (e.g. acids, CO2, and/or sulphur compounds) but also, on the other hand, with some specific, physical and chemical effects of the microorganisms themselves through the formation of biofilm on the surface. Moreover, the intrinsic properties of the cementitious matrix (physical properties, min-eralogical and/or chemical composition) can also influence the biofilm characteristics.
These deteriorations lead to a significant increase in the cost of repairing structures and to loss of production income, but may also lead to pollution issues resulting from waste water leak-age to the environment for example.
Also, building facades, and notably concrete external walls, can be affected by biological stains, which alter aesthetical quality of the construction, sometimes very quickly, and lead to significant cleaning costs.
In indoor environments, proliferation of bacteria and fungi on building materials is responsi-ble for health problems through the production of microbial volatile organic compounds, aller-gens and toxins. The bio-receptivity of construction materials conditions the proliferation of microorganisms on their surfaces. This is a significant issue all the more, as the economic and societal consequences of bacterial proliferation inside buildings are very important.
However, in some cases, microorganisms can have beneficial effects on cementitious materi-als when they are used for example as a way to protect and/or repair concrete in applications such as bacteria-based self-healing materials. New formulations of cementitious materials, in-corporating selected bacteria and suitable chemical precursors, are developed with the aim to fill micro-cracks in concrete and thus improve the durability properties. Moreover, living wall sys-tems, made of concrete with enhanced bio-receptivity, are being developed with the aim of using the buildings’ envelope to provide a higher surface of green areas. More and more re-search efforts are devoted to these topics related to cementitious materials-microorganisms interactions within local or trans-regional initiatives.
RILEM 253-MCI Technical Committee (2013-2018) aims to implement concerted approaches and comparison of research outcomes to move toward a better understanding of the phenom-ena and furthermore, to standardization (of test methods for example, there is a real shortfall in the domain) and/or certification.
The Delft conference, organized at TU Delft on 23 June 2016, was the midterm event of this TC. The conference consisted in (i) review presentations given by the TC members on the topics listed above, and (ii) a poster session by participants in the conference. These proceedings gather the review papers presented posters’ abstracts.

Dr. Virginie Wiktor, Dr. Henk Jonkers, Prof. Alexandra Bertron

Online publication: 2016
Publication Type: full_text
Public price (Euros): 0.00