Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Corrosion prevention of steel rebar embedded in the cement mortar under accelerated conditions: Combined effects of phosphate and chloride ions
Highlights PO4 3− and Cl− ions exhibit combined effect on mechanical and corrosion properties. The formation of FePO4 and γ-Fe2O3 impart corrosion resistance. Ca3(PO4)2 and Ca5(PO4)3Cl crystals fill the cement mortar pores. PO4 3− ions should be greater than Cl− ions for excellent corrosion resistance.
Abstract The present work focuses on the role of different amounts i.e. 0.295 and 2.95 kg/m3 ammonium phosphate monobasic (NH4H2PO4: APM) inhibitor and 1.2 kg/m3 NaCl as admixtures in cement mortar under wetting–drying accelerated condition to mitigate the corrosion of steel rebar. The results show that phosphate ions (from APM) react with NaCl and ordinary Portland cement (OPC) constituents to form Ca3(PO4)2 and Ca5(PO4)3Cl as hydration products, which led to make the cement mortar matrix dense and compact, and thus, improved the compressive strength after 28 days of water curing. Consequently, the phosphate ions in the cement mortar initiate the oxidation of embedded steel rebars immersed in 3.5 wt. % NaCl solution due to the formation of Fe(H2PO4)2, and FeHPO4 as intermediate. These could be transformed into stable and protective tertiary iron phosphate (FePO4) if optimum amount of phosphate ions is present but in the case of 0.295 kg/m3 APM, mostly phosphate ions consumed in the formation of Ca3(PO4)2 and Ca5(PO4)3Cl. Therefore, this sample became vulnerable to corrosion. On the other hand, 2.95 kg/m3 APM, the phosphate ions are significant and, thus, it helps to properly form the Ca3(PO4)2, Ca5(PO4)3Cl, FePO4 and maghemite (γ-Fe2O3).
Corrosion prevention of steel rebar embedded in the cement mortar under accelerated conditions: Combined effects of phosphate and chloride ions
Highlights PO4 3− and Cl− ions exhibit combined effect on mechanical and corrosion properties. The formation of FePO4 and γ-Fe2O3 impart corrosion resistance. Ca3(PO4)2 and Ca5(PO4)3Cl crystals fill the cement mortar pores. PO4 3− ions should be greater than Cl− ions for excellent corrosion resistance.
Abstract The present work focuses on the role of different amounts i.e. 0.295 and 2.95 kg/m3 ammonium phosphate monobasic (NH4H2PO4: APM) inhibitor and 1.2 kg/m3 NaCl as admixtures in cement mortar under wetting–drying accelerated condition to mitigate the corrosion of steel rebar. The results show that phosphate ions (from APM) react with NaCl and ordinary Portland cement (OPC) constituents to form Ca3(PO4)2 and Ca5(PO4)3Cl as hydration products, which led to make the cement mortar matrix dense and compact, and thus, improved the compressive strength after 28 days of water curing. Consequently, the phosphate ions in the cement mortar initiate the oxidation of embedded steel rebars immersed in 3.5 wt. % NaCl solution due to the formation of Fe(H2PO4)2, and FeHPO4 as intermediate. These could be transformed into stable and protective tertiary iron phosphate (FePO4) if optimum amount of phosphate ions is present but in the case of 0.295 kg/m3 APM, mostly phosphate ions consumed in the formation of Ca3(PO4)2 and Ca5(PO4)3Cl. Therefore, this sample became vulnerable to corrosion. On the other hand, 2.95 kg/m3 APM, the phosphate ions are significant and, thus, it helps to properly form the Ca3(PO4)2, Ca5(PO4)3Cl, FePO4 and maghemite (γ-Fe2O3).
Corrosion prevention of steel rebar embedded in the cement mortar under accelerated conditions: Combined effects of phosphate and chloride ions
Thanh Tran, Duc (Autor:in) / Lee, Han-Seung (Autor:in) / Kumar Singh, Jitendra (Autor:in) / Lee, Dong-Eun (Autor:in)
10.12.2022
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Interactive effects of moisture, chloride, and carbonation on rebar corrosion in mortar
| Elsevier | 2024