Evaluation of interaction properties of uniaxial geogrids with waste foundry sand

The reuse of waste materials can help alleviate problems related to placing them in landfill and can also preserve fast dwindling natural granular materials. Waste foundry sand (WFS) can be a promising candidate as a backfill material in the construction of mechanically stabilised earth (MSE) walls. In the design of such MSE structures, the interaction properties between WFS and geogrid reinforcement are important input parameters. In the present study, the interaction properties of a wide range of different polyester (PET) uniaxial geogrids with WFS in two common modes – direct shear and pullout – were evaluated using large-size interface direct shear and pullout tests. In the pullout mode, the interaction of the geogrid embedded in WFS under axial and transverse pullout was studied. The direct shear interface coefficients of four PET geogrids with WFS were found to be in the range observed in conventional fill materials. Higher axial and transverse pullout resistance factors were observed for geogrids with higher tensile strength and higher opening area ratio. Empirical equations were proposed to estimate the axial and transverse pullout resistances of geogrids at two pullout displacements. Finally, sensitivity analyses were carried out to identify the parameters significantly influencing the axial and transverse pullout resistances of geogrids in WFS.