Corrosion Performance of ChromX 2100, 4100, and 9100 Bars

Abstract

The corrosion resistance of ASTM A1035 CL (nominal Cr content of 2%), CM (nominal Cr content of 4%), and Type CS (nominal Cr content of 9%) steel reinforcing bars produced by MMFX Technologies under the respective trade names ChromX 2100, 4100, and 9100 were evaluated in uncracked concrete. The bars were tested both in the as-rolled condition as well as after sandblasting to remove mill scale. The corrosion performance of the ChromX bars was compared to that of conventional (ASTM A615) reinforcement in previous studies.

The ChromX bars exhibited a critical chloride corrosion threshold between 1.4 and 2.9 times greater than the critical chloride threshold of conventional reinforcement, with the ChromX 9100 bars exhibiting higher chloride thresholds and lower corrosion rates after initiation than the other ChromX bars. The average corrosion rate after initiation of ChromX bars ranged from 15% to 31% that of conventional reinforcing steel. Sandblasting was effective in decreasing the corrosion rate after initiation for ChromX bars, but did not significantly alter the chloride threshold.