Comparative study on the electric resistance of mortars made of low carbon binders

Passivation of Steel Reinforcement in Low Carbon Concrete

“…The change of the values over time and the differences between the different binder types are in good agreement with resistivities investigated at the same mortar mixes in a four-electrode setup with known geometry in a former investigation published in [44]. However, the storage conditions are not exactly the same in the current investigation and the investigations on the resistivity [44], because the specimens were sealed in [44] and, in the investigation described in this paper, the specimens can dry because the upper surface is exposed to the atmosphere. CSA shows a high R 0 in this investigation from the beginning, which starts to lower from the age of 14 days.…”

“…The highest R 0 from day 3 onwards is observed in the C-S-H series, followed by CSA. In the case of CSA, the high resistance is caused by a pore solution with comparably low conductivity; in the case of C-S-H, a dense microstructure causes this high electric resistance [9,44,45]. The R 0 values of the investigated geopolymers are very low, which is also consistent with the literature findings [33,46,47].…”

“…Also, the high resistivity of CSA was confirmed [17]. According to earlier investigations, this is an effect of a pore solution with comparably low conductivity [44]. The weak passivation of steel in CSA mortar observed in this study can be an effect of the lower pH of the pore solution and high amounts of…”

“…According to earlier investigations, this is an effect of a pore solution with comparably low conductivity [44]. The weak passivation of steel in CSA mortar observed in this study can be an effect of the lower pH of the pore solution and high amounts of SO 4 2− and Cl − , typical for CSA-based materials [10,11,13,15] and the test conditions where desiccation was impeded.…”

“…CSA shows a high R 0 in this investigation from the beginning, which starts to lower from the age of 14 days. The resistivity of the CSA mortar in [44] shows a rather linear increase over time. Similar observations are made by Carsana et al [17], where the resistivity of a CSA concrete in sealed specimens shows a slow decrease after a sharp increase within the first day, and a rather linear increase is observed in water-stored CSA specimens.…”