Permeability of the bonding interface between strain-hardening cementitious composite and normal concrete

Strain-hardening cementitious composite (SHCC) is ideal materials exhibiting ultra-high toughness, low permeability, and superior durability properties. SHCC is widely used for strengthening and repairing concrete structures. However, the permeability of the bonding interface between SHCC and normal concrete (NC) remains unclear due to the lack of experimental data. This study aims to investigate the impermeability of the SHCC-NC interface. The influences of interfacial roughness, interface agent, curing time, and substrate material on the permeability and splitting tensile strength are investigated. Results show that the impermeability of the bonding interface increases with the interfacial roughness and that the permeability coefficient of the SHCC-NC bonding interface can reach 1.40 × 10-11-1.08 × 10-12 m/s when the average height of sand filling reached 2-3 mm. The interface agent can improve the impermeability of the bonding interface. The impermeability of the bonding interface of the S-P composite specimen increased by 75% as the curing time is prolonged. The impermeability of the bonding interface between the new SHCC and existing NC is 5.7 times that of the interface between the new NC and existing SHCC. These differences are related to the maximum roughness of the substrate material’s surface. Finally, experimental results indicate that a linear expression is established between the impermeability and post-penetration splitting tensile strength of bonding interface.