Moisture content influence on the thermal conductivity and diffusivity of wood-concrete composite

The aim of the work reported in this paper is to determine the influence of moisture content on the thermal proprieties of wood-concrete composite, i.e. thermal conductivity and thermal diffusivity. The wood shavings have been incorporated, without any preliminary treatment, into a sand-cement mixture. Five formulations containing different percentage of shavings have been prepared and have been examined herein. The experimental results show that the lightening of concrete by wood shavings increases the thermal insulation capacity by decreasing the thermal conductivity and diffusivity; however these proprieties are strongly dependent on water content. The thermal conductivity increases rapidly with water content. Its experimental evolution with water content was confirmed by the comparison with three theoretical models. The values of the thermal diffusivity depend on the used counting model. The results stemming from three most used models are compared between them, and they show that in general the thermal diffusivity presents a maximum corresponding to a water content value Wm.