Evaluation of the Expanded Polystyrene’s shear modulus by torsion using an orthotropic approach

Abstract

In this paper an equations system was used and a numerical procedure was applied to determine, with an orthotropic approach, the shear modulus of Expanded Polystyrene (EPS) by experimental torsion tests using specimens from three orthogonal direction. The specimens used in this work were obtained from a EPS’s block used in the construction for soft soil stabilization called Geofoam. In their applications these blocks are subjected to compression, tensile and torsion strengths. The mean EPS specific mass was 26.51 ± 3.21 kg / m3 and its mature pearls had diameters ranging from 0.9 to 2.5 mm. The apparent shear moduli, obtained by torsion tests, fed the nonlinear system proposed by Lekhnitskiy and Semenov and developed for orthotropic materials. Such equation was solved using the Newton-Raphson numerical method, all possible solutions were appreciated. The results indicated that the average values of G of each plane can be represented by the orthotropic model, thus their orders of magnitude; Gxy = 6, 101 MPa, Gxz = 5, 796 MPa and Gyz = 5, 736 MPa.