Geopolymeric and cementitious mortars with the same strength class: comparison of the corrosion behaviour of embedded steel and galvanized steel reinforcements
EUROCORR 2014, Improving materials durability: from cultural heritage to industrial applications
Autore/i: Bellezze, Tiziano; Mobili, Alessandra; Roventi, Gabriella; Tittarelli, Francesca
Editore: Dechema - Associazione Italiana di Metallurgia
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Geopolymeric and cementitious mortars with the same strength class and workability
were studied and compared in terms of mechanical and corrosion behaviour of possible
reinforcements. To this aim, three different geopolymeric and cement mixtures
were manufactured in order to obtain mortars belonging to R1 > 10MPa, R2 > 15MPa
and R3 > 25 MPa strength class.
In particular, mortars based on geopolymer binder were prepared with fly ash, calcium
aluminate cement, a solution of sodium silicate/potassium hydroxide ratio of
0.85:1, with different concentration of KOH, and a sand/binder ratio of 2.7:1, by
weight. The respective three cementitious mortar mixtures were prepared with different
proportions of ordinary Portland cement and hydraulic lime as binders, different
water/binder ratio by weight and the same sand/binder ratio (3:1 by weight).
The corrosion resistance of steel and galvanized steel reinforcements was investigated
by free corrosion potential and polarization resistance measurements. Finally,
metallographic analysis on the cross sections of galvanized bars extracted from the
specimens was also carried out.
The results showed that, initially, the galvanized steel reinforcements are particularly
susceptible to corrosion in geopolymeric mixtures due to their high alkalinity. However,
after few days of curing, the corrosion rate decrease, even if this process is slower
than that of same reinforcements in cementitious mixtures. On the other hand, in
geopolymeric matrix, the steel reinforcements show a lower corrosion rate, if compared
with galvanized steel reinforcements, and their corrosion behaviour do not
change significantly with the type of binder.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/200904