Minimizing the water sensitity of clay-shale-wood cementing composites

The use of clay and wood waste in construction materials points out to a se nsitivity to water, which is susceptible to reduce their durability. This w ork has first been interested in the influence of different constituents on the extreme dimensional variations (EDV) of such cementing composites. A f ormulation allowing the conciliation of environmental imperatives, interest ing mechanical and thermal characteristics, and low density has been propos ed. However, the EDVs remain above the required objective. In order to reac h this value, different treatments have been examined. The addition of alka li-resistant fiberglass in the matrix did not lead to satisfactory results. Not only is the reduction of the EDVs insufficient for reasonable proporti ons of fibers, but this treatment also increases the proportion of absorbed water in presence of liquid water. Taken separately, both types of treatme nts used for wood particles - neutralization with hydraulic binders and ext raction with boiling water of hydro-soluble compounds - also do not allow a sufficient reduction of EDVs. However, the combination of these two treatm ents allows the achievement of EDV less than or equal to 1 mm/m. Such a tre atment improves the mechanical resistance without significantly altering th e thermal performances.