Sustainable renovation and building : the challenge of local materials – PRIMATERRE

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.

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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.