Characterising the short term low-strain radial tensile behaviour of a multi-axial geogrid.

It is recognised that the critical properties of multi-axial geogrids, when used for the stabilisation of unbound granular materials, are their interlock capability and shortterm, in-plane, low-strain, tensile stiffness in all radial directions. Their interlock characteristics are well understood, but not their short-term, low-strain radial tensile stiffness. To date wide-width, uniaxial CRS tensile tests carried out in multiple directions have been used to determine this property, but the validity of this approach has not been investigated. Therefore a new, in-plane, radial tensile test apparatus and test methodology has been developed for this purpose. Test data obtained from this new radial tensile test has been compared to that obtained from multi-directional uniaxial tensile testing and found to be closely correlated. Thus the multi-directional, uniaxial constant rate strain (CRS) tensile test is shown to be a reasonable and conservative means of determining the short-term, low-strain, radial tensile stiffness of multi-axial geogrids and the need for more elaborate testing methodologies is not required.