Compressive behavior of seawater sea sand concrete (SSC) composite columns with dual-functional C-FRCM jacket under eccentric loading

This study proposes a novel seawater sea sand concrete (SSC) composite column that integrates impressed current cathodic protection (ICCP) and structural strengthening (SS) using a carbon-fabric reinforced cementitious matrix (C-FRCM) jacket, aiming for a dual enhancement in durability and mechanical performance. To investigate its compressive behavior under eccentric loading and evaluate the effects of key ICCP parameters, eccentric compression tests were conducted on four SSC reference columns and ten SSC composite columns with C-FRCM jacket. The experimental parameters included eccentricity (60 and 210 mm), current density (25, 75 and 125 mA/m²), duration of ICCP (90, 150 and 270 days), and charge quantity (3.89 ×10⁵, 11.66 ×10⁵ and 19.44 ×10⁵ C). The results indicated that the ICCP system reduced steel reinforcement corrosion by up to 67 %, while C-FRCM enhanced load-bearing capacity, stiffness, and deformation of composite column by the maximum values of 12.4 %, 34.9 %, and 15.1 %, respectively, thereby achieving the dual functions of corrosion protection and structural strengthening. However, structural performance of composite columns showed a slight decline with increasing current density, duration and charge quantity. The charge quantity was identified as the dominant factor governing the deterioration of composite columns. Furthermore, the theoretical calculation formula for compressive behavior of the composite columns was proposed, which demonstrated a high accuracy, with an average error of 7 %, and tended to be conservative.