Residual mechanical performance and rust characterization of self-prestressing UHPM subjected to chloride-induced corrosion

Abstract

Chloride-induced corrosion poses extreme vulnerabilities to the strength degradation and delamination of reinforced concrete structures in the oceanic environment. For this reason, the self-prestressing effect produced from the synergy of the combined addition of expansive agent (EA) and steel fibre (SF) into the concrete is suggested to enhance the corrosion performance (cracking and degradation) of concrete-steel tubular columns (CSTCs). Four mortar mixtures were prepared with the no EA and SF, individual use of EA or SF and combined use. The corrosion rate was measured by the linear polarization resistance (LPR) method, while crack-width and pit-depth were measured with scanning electron microscopy (SEM). Test results revealed that the self-prestressing ultra-high-performance mortar (UHPM) prepared by the combined use of EA and SF reduced the corrosion rate, pit depth, and crack width up to 87.3%, 55.8%, and 68.3%, respectively. Furthermore, it also results in the highest residual compressive strength. The corrosion products characterized by using an energy-dispersive x-ray detector (EDX) and x-ray diffractometry (XRD) for self-prestressing UHPM were oxides with a volume ratio to parent iron of approximately 2, which is the lowest amongst all and justifies its superior performance.