The energy density involved during a chemical reaction could make chemical heat storage an excellent candidate for decreasing buildings energy consumption. Previous research focusing on pure or composite salt in sorbent-based porous matrix (zeolite, silica gel…) showed that the energy density and the heat transfer remain low due to the swelling of the salt and the specific surface decrease. Recently, new approaches using honeycomb ceramics as porous matrix proved the feasibility of the concept. Yet further work is needed to characterize and optimize the energy density and the heat and mass transfer within such composite. This project aims at designing energy dense and high powered architecture materials using impregnated salt in porous ceramic matrix. The reactor optimal geometry will be designed based on the Constructal approach from a heat and mass transfer point of view. Prototypes of optimal reactor will be built by 3D robot casting and characterised on a thermal and energy bases.

The French territory presents many old historical constructions classified as building open to the public (ERP). However, this architectural heritage in masonry is fragile regarding the fire risk as the disaster that occurred on April 15 at Notre-Dame Cathedral in Paris. After a fire, the heritage value of these ERP implies that, if a doubt of structural stability exists, the question of their demolition is generally ruled out, unlike contemporary constructions without architectural value. Moreover, when these buildings are classified as Historic Monuments (HM), they must be restored and, or at least be rebuilt as it was. In any case, the question of the structure stability subjected to fire remains. However, today, knowledge and tools to assess the post-fire structural stability of a masonry building are still missing. The DEMMEFI project proposes to respond to this problem by carrying out a post-fire structural assessment methodology for complex 3D masonry structures. This methodology will first be applied to a common span of the nave of Notre-Dame cathedral and then generalized to similar masonry historic buildings with high heritage value. The methodology developed will be based on the combined and optimized use of the two main existing numerical methods: the finite element method (FEM) and the discrete element method (DEM). A so-called hybrid FEM-DEM method will be proposed in order to combine the advantages of the FEM and DEM methods in order to simulate the mechanical behavior of masonry material. The problem of mechanical stability subjected to fire action (during fire and post-fire) will be provided by a thermo-mechanical characterization of equivalent materials (limestone and lime mortar) and assemblies. Moreover, an estimation of the spatio-temporal fire action on the vault extrados will be studied. The modeling strategy will be based on a multi-scale approach using the hybrid method from the material to the structure. Finally, the relevance of stability indicators in terms of limit thrusts, limit displacements or limit stresses will be studied for each type of sub-structure of the cathedral in order to propose practical verification methods contributing to the structural assessment of these complex heterogeneous structures.

In France, a number of civil nuclear facilities date from the 1960s and some of them will soon reach the limit of their service life. One of the issues at stake at the regional level is the management of the large volumes of waste generated by the deconstruction of reinforced concrete infrastructures. These demolition concretes are destined to be stored, whereas, due to the safety requirements of the infrastructures from which they are derived, they could constitute a quality material. The context of the nuclear industry offers a real opportunity for innovation through the investigation of a new way of recovery with minimal destructuring of the initial material. This new way of material recovery would be based on the reuse of reinforced concrete blocks deconstructed by cutting as modules for new constructions. This concept of reuse of structural elements exists in the building industry with in particular technical recommendations for the reuse of walls. However, brakes are still identified and in particular the ignorance of the properties of the constituent materials and a compartmentalization of die on the cycle. In the case of the concrete of power plants, their high mechanical properties, their rate of reinforcement often important make of these concretes good candidates for this type of recovery tending to reduce the "downcycling" by taking advantage of the performances of the deconstructed elements. In addition, the specific industrial context (nuclear structures of similar initial design) makes it possible to envisage deconstruction techniques adapted to an optimized recovery. The objective is therefore to develop modules that can be used in various applications within nuclear civil engineering (retaining walls, storage structures, secondary hydraulic structures, etc.). This would also ensure a virtuous path of recovery capable of absorbing, within the nuclear industry, the large volumes resulting from dismantling.

Aging of Civil Engineering structures generally leads to important economical concerns, mainly linked to the choice between their replacements or their life extensions. Developing a more general understanding of cement-based materials behaviors and of the mechanisms associated to their long-term behaviors is thus of the greatest interest both on the environmental and financial points of view. To set up such a sustainable methodology associated to the field of cement-based materials industry requires a deep understanding of their behaviors under the numerous environmental conditions that may occur. Being at the crossroad of several scientific domains such as nonlinear continuum mechanics, chemistry, mass transfers or computational solid mechanics, this scientific issue is a highly interdisciplinary one. Dealing with concrete structures, it is now clearly established that most of the macroscopic scale observed behaviors (among which the pathological behaviors, such as drying or delayed ettringite formation, are our main cause for concern because they may strongly decrease the durability of the structure) find their roots within a set of specific physical and chemical phenomena. Though the latter take place at fine scale, their consequences at macroscale may be quite important, with a huge impact on the durability of concrete structures and their life expectation. This fact is the cornerstone of the MOSAIC project. Our aim is to improve the links between those fine scale mechanisms and their macroscopic consequences. To build such bridges shall consist of two main steps: - First to drive experiments within specific environmental conditions in order to trigger different pathologies and to measure their consequences at macroscale; - Second to find out, for each pathology, which minimum set of mechanisms is mandatory to be modeled, at fine scale, in order to get an accurate and predictive strategy. Hence, contrary to the usual macroscopic models, our aim here is to identify the simplest physical and chemical mechanisms, and to embed those within a multi-scale numerical strategy. Considering the potential numerical difficulties, the MOSAIC project aims at focusing on the mesoscopic scale, which amounts to explicitly representing heterogeneities larger than 1 mm as well as their interfaces. Chief among the degradation mechanisms for concrete, cracking is of the major importance and is strongly related to the present challenges dealing with the durability of concrete Civil Engineering structures. For the latter, some specific long-term environmental conditions are known to be quite prejudicial by causing cracking and thus involving an increase of mass transfers, and finally increasing the risk of corrosion of steel in reinforced concrete. The MOSAIC project deals with two of those conditions: delayed ettringite formation and drying. They are complementary in the sense that the former leads to cement paste swelling, while the latter corresponds to cement paste shrinkage. Those two phenomena are involving degradation mechanisms associated to the fine scale of concrete, and so are strongly influenced by the material heterogeneity. Hence the use of a fine scale analysis is also of the strongest interest in terms of durability of concrete structures. On a global point of view, the expected results of the MOSAIC project are: - First to be able to quantify mechanical and transfer properties at macroscale from the knowledge of the potential shrinkage and swelling of the cement paste on the one hand and, on the second hand from the morphology and volume fraction of the aggregates. - Second, concerning DEF, the ability to quantify the effect of drying-wetting cycles and the improvement of the ability to predict the swelling due to DEF. The latter shall be done considering mix-design parameters, chief among them the choice of the aggregates. Depending on the effect of drying-wetting cycles, an evolution of the control test on DEF will be propose

Improvements of people health and of environmental quality of water are mainly based on wastewater treatment plants. Numerous progresses have been carried out concerning treatment processes but few studies deal with the concrete infrastructure degradations observed for about ten years in particular in nitrification/denitrification treatment units. Currently, the need of knowledge improvement is fundamental both for repair of existing constructions and for design of new constructions. WWTConcrete (Sustainable concrete for wastewater treatment plants) project deals with this objective and its multidisciplinary scientific partnership has defined a proposal on the infrastructure/material/process links in order to define operational strategies for sustainable infrastructure. The general strategy for the project consists in assessing the degradation state of concrete in SIAAP facilities and to correlate the observed degradations with recorded data on the effluents, in designing a lab pilot and implementing tests to reproduce real processes in well-defined conditions, in decoupling chemical and biochemical phenomena to understand cementitious material degradation, and in modelling biodeterioration both at the scale of cementitious material and at the scale of treatment unit. The expected deliverables of the project concern digital tool to optimise both material selection and operative conditions of the treatment process, and recommendations for evolving current standards, given that it an essential step for technological and skills transfer in particular in the field of civil engineering.