Thermal and mechanical performances of Mineralized Wood Concrete

The development of new concrete products is a key issue addressed to increase thermal performance of concrete for low energy buildings. The chapter presents the results of experimental and theoretical studies aimed at investigating the potential use of wood aggregates in substitution of natural ones to produce a more sustainable and energy friendly lightweight concrete, called Mineralized Wood Concrete (MWC). Exploiting this type of aggregates, which stem from wastes of woodworking activities, a triple purpose has been achieved: * preservation of natural raw materials; * reuse of wastes; * energy saving in buildings. Furthermore, the use of wood aggregates is a way to try to develop a sustainable concrete characterized by high thermal inertia, high thermal resistance and low weight. To this aim, wood aggregates were incorporated, after a preliminary treatment that consists into a mineralization with silica fume, into two types of concretes. One of these, constituting the matrix, was composed of cement, limestone filler, admixture and water. The other one was constituted by admixture, water and Flowstone®, which is a high performance cementitious binder developed for top quality concrete products. The effects of the addition of these aggregates on mechanical and thermal properties of concrete are here presented. In particular, mechanical performances were investigated with compressive strength test. A one-dimensional heat flow model was used to predict the effective thermal conductivity of MWC. The obtained low thermal conductivity values demonstrate that inclusion of wood aggregates into concrete reduces material density to a considerable extent and significantly increases the thermal resistance. Furthermore, the use of Mineralized WoodConcrete can be associated with the idea of a different typology of relatively heavybuilding envelope: this union could answer to the demand of well-insulated building envelope and concurrently characterized by high thermal mass. From this union, a series of other goals can be derived: low weight, environmentally friendly, easily industrialized and easy on-site casting. Consequently, applications of wood concrete in building constructions may be an interesting solution in order to improve sustainability and energy efficiency of buildings.