Service life of reinforced concrete structures made with blended cements and exposed in urban environment

Carbonation-induced corrosion is one of the main causes of degradation of reinforced concrete (RC) structures exposed outdoor in urban environment. To prevent steel corrosion, a durability design, that considers both the initiation and the propagation time, is of fundamental importance. At this aim, the resistance to carbonation of concrete and the steel corrosion rate in the exposure environment need to be known. This paper reports the carbonation coefficient and the corrosion rate of 7-day cured RC specimens made with different binders and exposed outdoor in Milan in unsheltered conditions. Corrosion rates in laboratory conditions with different temperatures and relative humidities are also reported. Experimental data were used to evaluate the service life in unsheltered condition. RC specimens made with Portland cement exhibited the lowest carbonation coefficient and corrosion rate, while specimens with 30% limestone and with 70% ground granulated blast furnace slag the highest.