Chloride Ion Penetration in RC and SFRC Precast Tunnel Lining Segments

Abstract

Steel corrosion induces distress in concrete structures, resulting in the cracking and spalling of the concrete cover, which accelerates further damage. Chloride ions (Cl–) and carbonation are the primary causes of steel corrosion in concrete. This study investigates the effects of Cl– in precast concrete tunnel lining (PCTL) segments through conducting various tests on cylindrical cores extracted from conventional reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) segments. The full-scale PCTL segments were fabricated and cured at an industrial precast plant. Experimental results show that the external specimens (extrados and intrados faces) of both the RC and SFRC PCTL segments exhibited lower Cl– penetration due to surface treatment using a cement slurry. The Cl– diffusion coefficient was a function of the exposure period and concentration of the salt solution for both the RC and SFRC segments. SFRC PCTL segments better resisted the ingress of Cl– than control RC segments due to a barrier effect induced by steel fibers (SF), which helped inhibiting the penetration of Cl– into the hardened concrete. This study demonstrates the potential of SFRC as a more durable alternative for precast segmental tunnel linings compared to conventional RC.