Evaluating the interaction between geogrid and recycled aggregate using pullout tests

The understanding of the fill material-geogrids interface is critical in the design of the reinforced fill structure. Pullout tests are commonly used to characterize the interaction between fill material and geogrids. In recent years, recycled aggregate shows some promising results to be used as an alternative fill material. Nevertheless, the interaction between selected recycled aggregate and geogrids requires further investigation. This paper presents experimental results focusing on the interaction between one type of recycled aggregate and two different geogrids through a series of large-scale pullout tests. The pullout resistance of the geogrid is correlated with the confining stress. When the confining stress increases from 10 to 30 kPa, the peak value of the pullout resistance also increases due to the improved interlocking of recycled aggregate with the geogrid. Tighter interlocking provides greater resistance to the applied pullout force, leading to higher pullout resistance. Increased vertical confining stress enhances contact between the geogrid and recycled aggregate, creating a stronger bond resulting in dilatancy of the aggregates, which in turn results in higher frictional resistance against the pullout force. The results show that the tested recycled aggregate can be used as a fill material in a reinforced fill structure.