Laurent Arnaud

The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles

Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.

Thermomechanical characterisation of asphalt pavements in laboratory conditions

Due to the viscoelastic properties of bituminous concrete, temperature changes result in significant mechanical effects. This paper proposes a method to assess, first, the intrinsic thermophysical parameters (thermal conductivity and heat capacity) of a bituminous mix, and then to characterise its mechanical behaviour by performing complex modulus tests. The determination of thermal properties of bituminous mixtures comes from an inverse analysis using finite-element software. The obtained intrinsic thermal parameters are essential for the fatigue law that depends on the viscous energy dissipation of bituminous concrete.