Long-term corrosion performance and monitoring for service life estimation of LC3 concrete systems

The performance of quenched and self-tempered (QST) steel bars embedded in concretes with Limestone calcined clay cement (LC3), fly ash (70% OPC and 30%fly ash – PFA), and traditional OPC was assessed in severe chloride environments. Additionally, the performance of commercially available, calcium nitrite-based inhibitors in the three binder systems was also evaluated. The specimens were subjected to an alternate wet-dry cycle using the ASTM G109 test method. The findings show that LC3 concrete performs better than the OPC and PFA systems with and without inhibitors. Furthermore, when the surface resistivity, ρ, is more than 37 kΩ.cm, the concrete has high ionic resistance and the macrocell current across the two rebars could not be established as described in ASTM G109 test method. This highlights the limitations of the ASTM G109 test method and the need for more sophisticated testing methods for assessing steel corrosion in highly resistive cementitious systems.