Bond Behavior of Seawater Sea-Sand ECC and GFRP Bars under Different Strain Rates and Bond Lengths: Experimental Study and Bond-Slip Modeling

ABSTRACT The shortage of fresh water and river sand in marine areas has become a major problem hindering the production of concrete and limiting infrastructure development there. To this end, engineered cementitious composites (ECCs) were prepared by using untreated sea sand and artificially configured seawater. The tensile and compressive properties of ECC and the bonding properties between glass fiber–reinforced polymer (GFRP) bars and ECC were studied. The effects of ECC matrix type, bond length, and strain rate on the bonding performance were considered in the center pullout test, and a bond-slip prediction model was developed. The results indicated that replacing fresh water and desalinated sea sand with seawater and sea sand led to a significant improvement in the mechanical properties of ECC. Additionally, the bond strength and slip between ECC and GFRP bars were also improved. The bond strength of seawater and sea-sand ECC with GFRP bars decreased with increasing bond length (l) but increased with increasing strain rate (ϵ). Conversely, slip increased with bond length (l) but decreased with strain rate (ϵ). The dynamic bond strength and dynamic slip calculation models for bond length and strain rate are established, and the prediction model of the bond stress-slip relationship between GFRP bars and ECC for bond length and strain rate is proposed to provide a theoretical basis for the application of GFRP bars and ECC in structures.