The constructions with primal materials (earth, stone) are several million in Europe, most of which must be renovated or with maintenance issues or simply bringing up to modern standards. The development / renovation of this type of construction is fraught with scientific lack of knowledeges (multiphysics complex material behavior) and societal bottlenecks (non industrial heritage, unrecognized skills) that the project proposes to remove.
There is currently no recommendation to guide the implementation of the primal materials in sustainable constructions or means of measurement recognized and guaranteed performance. This lack leads typically to apply methods and renovation unsuitable and / or prefer other building materials , environmentally less efficient but benefiting from standardized testing procedure . <br />Thus, the objectives of the project are to provide means for measuring and guarantee hygrothermal performance , mechanical and seismic resistance and ensure dissemination and development in the light of an analysis of institutional conditions, of primal material constructions. To achieve these objectives , a global, multi-scale and multi-disciplinary (materials, energy and sociology of innovation , laboratory and in situ , experiment and modelling) research is proposed. <br />At the level of the material, earth as a rammed earth, mortar and render will be studied. The addition of particles (fibers respectively) plant is studied here for their hygrothermal(mechanical, respectively) performance. In some cases it may be appropriate to use these materials for renovation or for new buildings. <br />At the institutional level, the purpose of bringing, from the implementation of the research program, and throughout his leadership, the constraints related to the structure of the construction industry and the place occupied in it by actors historically invested in the primal construction materials. <br />In the end, the project PRIMATERRE will propose to develop design guidance and recommendation and teaching modules. The project should give insights for both on a scientific and practical level, i.e. also realistic in terms of economic and political conditions in the construction sector in France and Europe.
The first phase of the project is to define the datas, materials and structures chose as references that will be used later for all project developments . It has also as a starting point a study and analysis of existing institutional and professional expectations.
The second phase focuses on the quantification of hygric and hygrothermal behaviour of clay based construction materials. It is based on an experimental study using two scales ( sample wall ) interpreted in the light of thermodynamic and mechanical coupled modeling . Dedicated computer codes are then used to verify the ability of the numerical models developed to reproduce the experimental results and to quantify the interest of taking into account all the couplings. Finally, the instrumentation of the pilot sites will allow us to test the applicability of these models and the measurability of the parameters identified. In parallel, the seismic behavior is studied by a campaign of experimentation at 1:1 scale on pilot instrumented buildings ( behavior in the short and medium term) , and on old buildings in France in areas of medium seismicity. Based on these field datas, different loading scenarios will be studied numerically to observe the maximum tolerable seismic loading by the structure and main modes of failure ( in plane and out plane). In addition , simplified methods, based on the development of equivalent discrete models will be developed for fast and efficient evaluation of the mechanical performance of structures.
Finally, the last phase of the project is to «translate« the scientific results obtained in order to make them usable in the context of teaching modules and design guidance for professionals.
The use of local materials is characteristic of most of millions of housing built before 1948 in France. These materials are not industrially processed and therefore lead to a significant decrease of grey energy consumption. However, due to lack of scientific knowledge, there is currently no clear recognized guidance for their set-up, or means of measurement to guarantee their performance.
This lack commonly leads to apply renovation and construction methods which are unsuitable, and / or to prefer other building materials, environmentally less efficient, but benefiting from standardized testing procedure. In the best case, companies rely on their empirical knowledge of these buildings.
Thus, the challenge of this proposal is to explore ways to measure and guarantee hygrothermal, mechanical and seismic performances of local materials and ensure their dissemination and development through an analysis of institutional conditions.
To achieve this objective, we propose to identify and measure, through physico-mechanical modeling and experiments at different scales (laboratory, on site), the key parameters needed to describe the hydro-thermal behavior of buildings and seismic. In this context, we will study the impact of natural vegetable fibers additions on the behavior of the studied clay soils.
The approach will be validated on the rammed earth and rough masonry constructions, which are the most representative of old buildings (before 1948).
Ultimately, PRIMATERRE project will allow the development of design guidance and training modules.
Jean Claude MOREL (Laboratoire public)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
EVS-RIVES Laboratoire Environnement Ville Société
LOCIE Laboratoire Optimisation de la Conception et Ingénierie de l’Environnement
LTDS-ECL Laboratoire de Tribologie et Dynamique des Systèmes
Help of the ANR 790,000 euros
Beginning and duration of the scientific project: February 2013 - 42 Months