Rate-Dependent Bonding of Steel Reinforcement in Geopolymer Concrete

In this work, the dynamic pullout experiments with loading rates ranging from 0.1 to 100 MPa/s (0.0145 to 14.5 ksi/s) were conducted to investigate the bond behavior between the metakaolin-based geopolymer (MKG) concrete and the plain and deformed steel reinforcement. A rate-dependent bonding behavior between the MKG concrete and the steel reinforcement was observed. Using an analytical model, the effects of the dynamic properties of MKG concrete and the interfacial properties at MKG-steel interface were quantitatively characterized. The morphologies of the bonded and failed interfaces were also examined and analyzed, showing different failure mechanisms associated with varying loading rates. These results link the loading rate-dependency of the MKG-steel bonding behavior to the enhanced chemical adhesion at the MKG-steel interface. Keywords: interfacial bonding; metakaolin-based geopolymer concrete; rate dependency.