The chloride-induced corrosion of a fly ash concrete with nanoparticles and corrosion inhibitor

Abstract

The urge to reduce the carbon footprints from cement production warrants the development of more sustainable approaches in the construction industry. Towards this, the long term corrosion resistance of the embedded steel rebar in a novel ternary-blended reinforced concrete system with 56 wt% Ordinary Portland cement (OPC), 40 wt% fly ash, 2 wt% nanomodifiers, and 2 wt% corrosion inhibitor (referred to as CFNI) was studied by chemical and electrochemical tests in a simulated chloride environment for 180 days. The performance was compared with three other concrete systems (CC (100% OPC), CF (60 wt% OPC and 40 wt% fly ash) and CFN (58 wt% OPC, 40 wt% fly ash and 2 wt% nanomodifiers). The electrochemical results indicated a significant enhancement in the corrosion resistance of steel in the CFNI concrete as compared to other systems. A five times higher value of polarization resistance (Rp) is obtained in CFNI, as compared to the control concrete, indicate the better resistance of CFNI. Further, in CFNI specimen, the chloride ingress rate was significantly lower and the Field Emission Scanning Electron Microscopy (FESEM) images showed no microcracks or pores at the corroded concrete-steel interface of CFNI specimens. The apparent diffusion coefficient (Dcl) of the concrete system was determined using the bulk diffusion test and chloride profiling. The value of Dcl for CFNI concrete was found to be one order less in magnitude than other concrete specimens, indicating the enhanced resistance against chloride attack. These results show that CFNI concrete is a promising ternary-blended concrete mix to achieve long corrosion-free service life for the structures in aggressive chloride environments.