Comparison of the effect of organic and inorganic corrosion inhibitors on the rheology of self-compacting concrete

This paper reports on the effects of using an organic and an inorganic corrosion inhibitor in self-compacting concrete (SCC). The respective organic and inorganic inhibitors used were of a migrating corrosion inhibitor (MCI) and a calcium nitrite inhibitor; the former inhibitor was used in a fly ash and a silica fume SCC and the inorganic inhibitor was used only in a fly ash SCC. It was shown that the use of the inhibitors in the traditional SCC powder pastes, at temperatures in the range of 20-40 °C, extended the initial setting times of the cementitious mixtures. From this research, the relationship between the initial and final setting times of the traditional and inhibited-SCCs was developed for the first time. Indications are that the inhibitors reduced the viscosity and the segregation resistance of the traditional SCCs but there were differences in the effects of each inhibitor on the deformability and the workability retention of each type of SCCs. The greatest effect was from the use of the organic MCI in the fly ash SCC where the setting times and the deformability were appreciably impacted.