Passivation behaviour of mild steel embedded in magnesium potassium phosphate cement-calcium sulphoaluminate cement blended paste

This study did a pioneer work focused on the passivation of mild steel embedded in magnesium potassium phosphate cement (MKPC)-calcium sulphoaluminate cement (CSA) blended paste via electrochemical mea-surements and materials characterization techniques. Results showed that 30 % CSA addition in MKPC leads to a passivity of mild steel much higher than that in Portland cement (PC) paste. The passivity of mild steel increased with an increase in CSA content in MKPC paste due to an increase in pH and phosphate concentration in pore solution. The formation of iron phosphate and Fe2+ oxide in passive film of MKPC-30 %CSA contributes to its highest passivity.

Automated summary

This study explores the passivation of mild steel embedded in magnesium potassium phosphate cement-calcium sulphoaluminate cement blended paste. The results show that adding 30% calcium sulphoaluminate in magnesium potassium phosphate cement leads to higher passivity of mild steel compared to Portland cement paste. The increased passivity is attributed to the higher pH and phosphate concentration in the pore solution, as well as the formation of iron phosphate and Fe2+ oxide in the passive film of MKPC-30%CSA.