Interface-controlled chloride corrosion in grouted sleeve joints of prefabricated RC elements: Performance enhancement using duplex stainless steel (Grade 2205)

Prefabricated reinforced concrete (RC) systems are efficient in terms of construction, but their durability is highly dependent on the behaviour of joint regions with several material interfaces. This research examines the chloride-induced corrosion performance of prefabricated beam-column joints connected by grouted sleeves, as compared with traditional cast-in-situ counterparts. The study employed an experimental-analytical method with wetting-drying cycles in a 3.5% NaCl solution to represent severe environmental exposure. The findings show that prefabricated joints demonstrate faster corrosion, with corrosion initiation 40-60% earlier than in cast-in-situ joints. The rate of corrosion was about 2.8 times faster, and the chloride diffusion coefficient increased by 2.5 times, confirming increased transport via the interfacial regions. Damage was concentrated at the sleeve interfaces, with a Damage Localisation Index (DLI) of about 0.62, and led to wider cracks than observed in traditional structures (more than twice the width). This study shows that the corrosion behaviour of prefabricated joints is largely controlled by the interface rather than the bulk properties. Targeted application of duplex stainless steel (Grade 2205) in key areas was effective in delaying the onset of corrosion and in diminishing its impact, showing the benefit of using this material in critical areas. The research provides evidence of interface-controlled corrosion and highlights the need for interface engineering and material design to enhance the sustainability of prefabricated concrete structures.