Characterization of environmental cracking of cathodically polarized prestressing steel in a simulated concrete environment

In order to investigate the environmental cracking tendency of prestressing steel tendons under cathodically polarized conditions, a series of slow strain rate tests were conducted using smooth and notched specimens in simulated concrete porewater environments. Applied potential was varied from -0.500 V to -1.500 V(SCE) at intervals of 0.200 V, and the pH range was 8.0 to 12.5. Based on the test results presented in terms of time-to-failure, reduction in crosssectional area and load at failure, potential regimes for susceptibility to hydrogen embrittlement in saturated Ca(OH)2 solution were identified. SEM analyses performed for both notched and smooth specimens tested at -0.700 V and -1.300 V in saturated Ca(OH)2 solution showed that different fracture mechanisms operate at these two potentials. The cracking processes have been explained based on the test results and SEM analyses. Based upon the data obtained, the steel showed higher resistance to environmental cracking at pH 9.8 and 8.0 than for 12.5. The applicability of the results to cathodic protection of prestressed steel in concrete is discussed.