Silane-based corrosion inhibitor to reduce the carbonation rate of existing Italians high-speed railway’s tunnels

Concrete-based tunnels for high-speed railways should exhibit remarkable durability, ensuring extended service life. The use of protective coatings and migrant corrosion inhibitors offers a viable solution to enhance the longevity of existing tunnels designed with ordinary service life or reduced concrete covers. The purpose of this work is to evaluate the effectiveness of a silane-based migrant corrosion inhibitor applied on the surface of the concrete of exhisting Italian high-speed railways tunnels. The effect of the surface treatment has been evaluated through accelerated carbonation test while the carbonation depth at the end of the service life of tunnels was assessed using the Fick's law. Experimental results evidenced that the use of migrant corrosion inhibitor allows to strongly reduce the risk of carbonation of concrete cover at the end of the service life both on areas exposed to wet-and-dry cycles and on regions with dry atmosphere.