TY - JOUR
T1 - Reinforced concrete exposed to external ammonium sulfate attack in fertilizer factories
T2 - Test method focused on reinforcement corrosion, migration coefficient, and microstructural changes
AU - Martins, Monalisa Coelho
AU - Silva, Anelize Seniski
AU - Capraro, Ana Paula Brandão
AU - Remenche, Igor Rossi
AU - Medeiros, Marcelo H.F.
AU - De Souza, Diego Jesus
PY - 2025
Y1 - 2025
N2 - This study investigates the depassivation of carbon steel in reinforced concrete exposed to external ammonium sulfate contamination, focusing on the corrosion process and sulfate ion migration. Over a 215-day period, reinforced concrete specimens with 2.5 cm and 5.0 cm rebar coverages were monitored using the linear polarization resistance (LPR) technique to measure corrosion current (Icor). Depassivation was detected at 100 days in contaminated samples with a 2.5 cm cover, exhibiting a corrosion rate of 0.368 μA/cm2 and a non-stationary migration coefficient of 3.3x10⁶ cm2/s. Mechanical testing revealed a 40 % reduction in compressive strength in contaminated specimens compared to reference samples. Mass variation tests indicated an 861 % increase in mass for the series exposed to the aggressive solution, suggesting the formation of deleterious products. Thermodynamic modeling with GEM-Selektor (GEMS) software and scanning electron microscopy (SEM) analyses confirmed the complete transformation of AFm phases into secondary ettringite, along with significant degradation of C-S-H, sharp pH decline, and portlandite dissolution. These findings suggest that corrosion induced by ammonium sulfate is primarily due to the chemical action of sulfate ions (SO4−2) rather than the anticipated pH reduction front reaching the reinforcement. This research provides new insights into the mechanisms of steel corrosion in reinforced concrete subjected to ammonium sulfate attack, highlighting the critical role of sulfate ion interactions in the degradation process.
AB - This study investigates the depassivation of carbon steel in reinforced concrete exposed to external ammonium sulfate contamination, focusing on the corrosion process and sulfate ion migration. Over a 215-day period, reinforced concrete specimens with 2.5 cm and 5.0 cm rebar coverages were monitored using the linear polarization resistance (LPR) technique to measure corrosion current (Icor). Depassivation was detected at 100 days in contaminated samples with a 2.5 cm cover, exhibiting a corrosion rate of 0.368 μA/cm2 and a non-stationary migration coefficient of 3.3x10⁶ cm2/s. Mechanical testing revealed a 40 % reduction in compressive strength in contaminated specimens compared to reference samples. Mass variation tests indicated an 861 % increase in mass for the series exposed to the aggressive solution, suggesting the formation of deleterious products. Thermodynamic modeling with GEM-Selektor (GEMS) software and scanning electron microscopy (SEM) analyses confirmed the complete transformation of AFm phases into secondary ettringite, along with significant degradation of C-S-H, sharp pH decline, and portlandite dissolution. These findings suggest that corrosion induced by ammonium sulfate is primarily due to the chemical action of sulfate ions (SO4−2) rather than the anticipated pH reduction front reaching the reinforcement. This research provides new insights into the mechanisms of steel corrosion in reinforced concrete subjected to ammonium sulfate attack, highlighting the critical role of sulfate ion interactions in the degradation process.
KW - Ion migration
KW - Corrosion
KW - Ammonium sulfate
KW - Thermodynamic modeling
KW - Linear polarization resistance (LPR)
U2 - 10.1016/j.jobe.2025.112112
DO - 10.1016/j.jobe.2025.112112
M3 - Journal article
SN - 2352-7102
VL - 104
JO - Journal of Building Engineering
JF - Journal of Building Engineering
M1 - 112112
ER -
