Poissons ratio of paving and subgrade materials

Poisson s ratio (v or )i) is the ratio of transverse strain to longitudinal strain in an axial loaded specimen. 

Poisson s ratio is a basic parameter used in analytical pavement design methodologies (based on stress/strain calculations). 

On paving and subgrade (soil) materials, Poisson s ratio is affected, among other parameters, by the elastic modulus of the material, the temperature, the cohesion, coarseness and roughness of the particles and the degree of saturation. 

The typical values usually assumed for calculating stresses/strains in the pavement s layers are as follows 0.35 or 0.4 for asphalts, 0.30 or 0.35 for the unbound base/sub-base material and 0.30 or 0.35 for the subgrade. 

American Association of State Highway and Transportation Officials, 2008. 

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