Corrosion resistance of wollastonite modified magnesium phosphate cement paste exposed to freeze-thaw cycles and acid-base corrosion

Abstract

This paper investigates the compressive strength loss of wollastonite modified magnesium ammonium phosphate cement (MAPC) and magnesium potassium phosphate cement (MKPC) paste after exposure to NaCl freeze-thaw cycles, alternation of dry-wet (water medium and 3 % NaCl medium), H2SO4 and NaOH corrosion. The compressive strength loss was applied to characterize the corrosion degree of specimens. Results indicated that the addition of wollastonite has a positive effect on the resistance to NaCl freeze-thaw cycles, alternation of dry-wet, H2SO4 and NaOH corrosion. The number of NaCl freeze-thaw cycles, alternation of dry-wet and the immersing days in H2SO4 and NaOH solutions led to the acceleration of corrosion. NaCl freeze-thaw cycles and alternation of dry-wet had a little corrosive effect on the wollastonite modified magnesium phosphate cement (MPC) pastes. However, wollastonite modified MPC pastes were seriously corroded by the immersion of H2SO4 and NaOH solution. MKPC showed the lower compressive strength loss when the samples were exposed to NaCl freeze-thaw cycles and dry-wet cycles in NaCl solution. While, in the condition of dry-wet cycles in water, MAPC behaved a lower compressive strength loss. Additionally, MAPC performed a higher compressive strength loss in H2SO4 corrosion environment than that of MKPC. On the other hand, MKPC showed better resistance to compressive strength attenuation.

Keywords

• Magnesium phosphate cement
• Freeze-thaw cycles
• Alternation of dry-wet
• Compressive strength
• Corrosion