Eco-conception durable d'ouvrages instrumentés en béton armé situés en environnement maritime – DEMCOM
Durable and Environmental design of Monitored COncrete structures in Marine environment
This interdisciplinary project deals with Durability, Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) of Reinforced Concrete (RC) structures under marine environment like bridges, floating turbines... The objective is to develop an eco design method to maximize service life and minimize environmental impacts and costs of structures submitted to chloride ingress. These stakes require monitoring results to be directly integrated in durability models to improve the service life prognostic.
Development of an eco design method to maximize service life and minimize environmental impacts and costs of monitored RC structures submitted to chloride ingress.
Owner of marine infrastructures such as wharfs, dykes, harbors, floating wind turbines…, owe the society the justification of sustainable long-living structures. The conventional design approach for durability of marine concrete structures is nowadays prescriptive; this results in material constituents and proportion, construction practices and cover depth provisions according to exposure classes. But, many researchers and engineers have pointed out that this prescriptive approach ignores the performance of the various binders added to the concrete. In addition, it does not provide means to monitor or control the presumed concrete quality versus aggressive migrating agents. It is obvious that designers should pay attention not only to Life Cycle Cost (LCC), but also to Life Cycle Assessment (LCA) in terms of greenhouse gas emissions (CO2). Both of these life cycle analyses require models, data coming from the Life Cycle Performance (LCP) behavior in order to analyze the critical issues when considering practical implementations. To be meaningful and effective, the LCA and LCC analysis must rely on a time-variant approach including losses of durability affecting the long term performance of the structure. For this reason, the standard prescriptive approach will be replaced by a performance-based approach, relying on predictive models supported by experimental data which are monitored with resistivity probes in DEMCOM project. The DEMCOM project is therefore based on scientific excellence and transdisciplinary research in the fields of cementitious material characterization, reinforced concrete durability modelling in marine environment, NDE monitoring, LCA and LCC Analysis. Combining these fields implies innovative methods and processes. We assume that solution oriented mindset should drive concrete structures design and that both durability and environmental performances have to be considered and improved simultaneously in order to achieve best performance throughout their life cycle in terms of risks, costs and environmental impacts. The aim of this project is to develop a method for identifying action levers to improve and optimize the global performances integrating environmental and economic indicators of concrete marine structures, knowing that the lifetime could go from some decades (Offshore Wind Turbines) to more than 100 years (such as dykes, wharfs…). The novelty is based on the holistic vision which combines several disciplines, the use of material, environmental or economic data and the combination of models. The aim is also to provide methods and tools usable by a designer.
The aim of the DEMCOM project is to tackle all these challenges through the major issue that affects marine concrete structures integrity: alteration by chloride ingress. For this purpose, this project will be divided in four Tasks (T). The methodological approach, described by the figure, is the conducting line of the DEMCOM project.
Task 1 is dedicated to the management of the project.
The main objective of Task 2 (T2) is to drive an experimental campaign with slag blended concrete slabs instrumented with the recently developed resistivity sensor designed for monitoring resistivity profiles over the whole thickness of a concrete structure. It is intended to address new scientific challenges: i) measuring and analyzing the electrical, conductive and capacitive phenomena, in order to extract not just one but two complementary observables, resistivity and chargeability, and their distribution in the material with a single probe ii) it would be possible to evaluate the kinetics of water and chloride penetration for concrete slabs exposed to tidal iii) analysing these outpouts data to get the input of the transport model integrating the processes of chloride and liquid transport.
Task 3 (T3) is the main part of the project. It has to combine durability modeling and multi-scale modeling by validating modeled results with experimental results obtained in T2 by monitoring. T3 is dedicated to develop a multi-scale model to estimate the concrete transport properties (input of the durability model) from the concrete compounds (technological parameters), as required for combination with LCA and LCC models. Indeed one challenge of the project is that the durability and LCA/LCC models should use the same inputs which are technological parameters and environmental parameters. This will be developed in the case of other binders than Portland cement as slag.
The key ingredients are respectively: 1) an appropriate hydration model to determine the amount of each phase, 2) a morphological model to describe their geometrical organisation and repartition across different length scales and 3) a suitable homogenization schemes to successively upscale the macroscopic properties of interest from those of each phase at the microscopic scales
Task 4 will be devoted to the combination of durability LCA and LCC models for identifying the most favorable material solution. To optimize the design also by reducing the calculation time of the method, Sensitivity Analysis (SA) will be developed to identify the action levers for maximize service life and minimize environmental impacts and costs. Different scenario will be studied for giving recommendations dedicated to the designers to also accept environmental LCA combined with LCP analysis as decision-making tool. Advice includes optimum concrete mix design to meet specific surrounding conditions, corrosion protection for reinforcing steel by considering LCC LCA LCP analysis.
The results are published in scientific papers or in conferences. All are available on hal site(https://hal.science/search/index?q=demcom). The data are available on
under construction
Ce projet interdisciplinaire a pour but de coupler durabilité et Analyse de Cycle de Vie et Analyse de Couts afin de développer une méthode d’éco-conception appliquée aux structures en béton situées en environnement maritime comme les éoliennes offshores, les ponts, les quais…. Les maitres d’ouvrages garantissent une durée de vie de leurs ouvrages sans tenir compte de l’impact du choix du béton, par exemple, sur l’environnement. Cette méthode d’éco-conception permettra de maximiser la durée de vie de ces structures tout en minimisant leurs impacts environnementaux et leur cout, ceci en prenant en compte la phase de maintenance et donc les données d’auscultations obtenues à partir d’évaluations non destructives. Des méthodes d’analyse de sensibilité seront développées et utilisées afin d’identifier les leviers d’action (paramètres technologiques tels que la composition du béton, le choix du ciment etc…) sur lesquels il faudra agir pour obtenir une structure eco-durable à moindre coût.
Coordination du projet
Stéphanie Bonnet (INSTITUT DE RECHERCHE EN GÉNIE CIVIL ET MÉCANIQUE)
L'auteur de ce résumé est le coordinateur du projet, qui est responsable du contenu de ce résumé. L'ANR décline par conséquent toute responsabilité quant à son contenu.
Partenariat
UNIV. Gustave Eiffel - MAST UNIV. Gustave Eiffel - Département Matériaux et Structures
GeM - Univ. Nantes INSTITUT DE RECHERCHE EN GÉNIE CIVIL ET MÉCANIQUE
BYTP BOUYGUES TRAVAUX PUBLICS SA
Aide de l'ANR 518 165 euros
Début et durée du projet scientifique :
- 48 Mois
