This paper describes a series of pullout tests that were carried out to investigate the role of transverse and longitudinal members (T & L-members) on pullout resistance of a polyester (PET) geogrid. Pullout tests were conducted on four different geogrid configurations with 0, 4, 8 and 16 T-members at three normal stress embedded in bottom ash and fly ash. The pullout resistance increased with increase in number of T-members and normal stress. However, due to different average particle size, the bearing resistance offered by T-members triggers in fly ash earlier than that in bottom ash. Tests were also conducted to study the influence of spacing and number of L-members. It was observed that the zone of influence of individual L-members overlap at close spacing that reduces the pullout load. This study demonstrates that T-members contribute almost 30–60% towards pullout resistance and exhibit higher contribution at larger confinement stress. © 2019 Elsevier Ltd