Chloride-Induced Corrosion in Reinforced Mortar, Modified with Core-Shell Micelles

This work reports on monitoring chlorideinduced corrosion in reinforced mortar specimens, with and without addition of polymeric nano-aggregates in the mortar mixture. The investigation is a novel approach to control steel corrosion in reinforced concrete, hereby reporting the preliminary results, related to one of the main objectives: studying the influence of admixed polymer nano-aggregates (in the form of PEO113-b-PS218 core-shell micelles with a very low concentration of 0.006 wt.% per mortar weight) on the corrosion behavior of the steel reinforcement, compared to reference, micelles-free mixtures. Materials and methods: The investigated specimens were reinforced mortar cylinders, h = 150mm, d = 40mm, with embedded “as received” construction steel FeB500 HWL of d=8mm (5 replicates per group and per condition were monitored). The specimens designation is as follows: corroding groups OPCcorr (micelles-free) and PoOPCcorr (with micelles) and reference groups, with and without micelles, PoOPCref and OPCref respectively. All specimens used OPC CEM I 42.5, water-to-cement ratio 0.6, cement-to sand ratio 1:3. Curing of the specimens was performed for 7 days in fog room (20oC, 98%RH); conditioning was in lab environment (20oC, lab air) for the total duration of the test of 320 days. The corroding specimens were 1/3 of height immersed in highly aggressive medium of 10% NaCl, the reference (non-corroding specimens) in tap water. The experimental methods involved were as follows: Open circuit potential (OCP) monitoring for all cells (all values reported vs SCE); Electrochemical Impedance Spectroscopy (EIS) and Potentio-dynamic polarization (PDP), using EcoChemie Autolab; SEM imaging of the steel/cement paste interface for all conditions, coupled with EDX analysis for composition of hydration/corrosion products (using ESEM Philips XL30);