Effect of mix proportions on corrosion of Swedish iron in ordinary Portland cement mortars at elevated temperatures

Abstract EN

Linear polarization resistance (LPR) measurements have been used to study the corrosion behavior of Swedish Iron samples embedded in Ordinary Portland Cement (OPC) mortar containing various levels of sodium chloride admixture up to 10 % by weight of OPC.

Mortars with 1:1 and 4:1 aggregate / cement ratios are compared and tests are made across a range of temperatures from 20-90°C.

The 4:1 A/C samples show serious pitting corrosion, characterized by low polarization resistance (Rp) at chloride levels of 1 % and above, whereas the 1:1 A/C samples gave high Rp-characteristic of the passive state except at the 10 % chloride level, where Rp was high at low temperature, fell abruptly as the temperature was raised above 50°C, accompanied by a drop in potential.

It is concluded that the presence of a dense cement matrix is crucial in determining the resistance of embedded iron or steel to chloride attack.