Application of Sacrificial Point Anode for Prevention of Steel Corrosion in Cracked Concrete

摘要

The effectiveness of a commercially available sacrificial point anode for corrosion prevention of steel in cracked concrete is presented. Reinforced concrete prisms with dimensions of 150 mm x 150 mm x 500 mm were prepared with a water to cement ratio (W/C) of 0.4 showing crack widths ranging from 0.1 to 0.4 mm obtained by pre-cracking. These specimens were exposed to three conditions: (1) laboratory air (temperature of 20±2°C and relative humidity of 60%); (2) immersed in 3% NaCl solution; and (3) dry/wet cycles of above mentioned conditions. Measurements included the free corrosion potential, polarization behavior of the sacrificial point anode, anodic-cathodic polarization curve of the reinforcement steel and visual observation. The test results show that the sacrificial point anode was effective to prevent the embedded steel from corrosion in cracked concrete. Specimens exposed to dry/wet cycles or immersed in 3% NaCl solution demonstrated a better protection than those exposed to laboratory air due to the high moisture condition. Thus, a sacrificial point anode becomes active to protect the steel bars even in cracked concrete.