Corrosion of galvanized steel in dilute Ca(OH)₂solutions (pH 11·1–12·6)

Hydrogen embrittlement risk of high strength galvanized steel in contact with alkaline media

“…The Ca content decreases with the increase of pH which makes the passivation more difficult to occur. Similar trend was found in the response of galvanized coatings of reinforcement [17,[30][31][32]. The effect of the stress level in the steel can also be observed in the Fig.…”

“…The ability to genérate CaHZ crystals in the environment is fundamental in this stage, as it stops the hydrogen evolution and passivates the galvanized steel. The models to explain the corrosión differences at different pHs previously reported 100 [17,21,22,[30][31][32], are based on the Ca 2+ saturated media and on the concrete pores. In this respect, the evolution of cement hydration during first hours and changes in the pore solution composition are vital [35].…”

Problems and normative evaluation of bond-strength tests for coated reinforcement and concrete

“…[20][21][22] Another group of authors claim that a zinc-coated reinforcement easily becomes passivated in an environment with a pH value of 13.3 by forming non-soluble Ca[Zn(OH) 3 ] 2 ·2H 2 O; sulphate anions also have a positive effect on passivation. [23][24][25][26][27][28][29] Another phenomenon -apart from the negative effect of zinc on the corrosion resistance of a reinforcement -a detrimental effect of zinc during the concrete hardening also needs to be mentioned. It was proven that zincates slow down the hardening of concrete and, with regard to the water content in concrete, they can extremely deteriorate the mechanical properties of concrete.…”

Zhodnocení vlivu koroze žárově zinkované oceli na soudržnost hladkých prutů s betonem třídy „NSC“

“…anodické korozní rozpouštění zinku ve výše zmíněném alkalickém prostředí, tedy i za přítomnosti Ca 2+ kationtů lze popsat následujícími dílčími reakcemi (2), přičemž první z uvedených dílčích reakcí se odehrává na povrchu kovu a druhá již v samotném elektrolytu [22][23][24][25][26]:…”

“…Po překročení kritické koncentrace těchto iontů v elektrolytu na fázovém rozhraní se zinkovnou ocelí dochází k precipitaci ZnO dle (3) [24][25][26][27][28][29]:…”