Performance evaluation of fresh-to-fresh cast SCC/ECC and SCC/UHPC composites under the coupling effect of freeze-thaw and deicing solution

This study addresses the research gap in freeze-thaw performance of fresh-to-fresh cast (hot-jointed) composites by examining the effects of freeze-thaw cycles and sodium chloride on self-consolidating concrete (SCC) combined with engineered cementitious composites (ECC) or ultrahigh performance concrete (UHPC). The potential use of hot-joint techniques for integrating ECC and UHPC with SCC to promote the sustainable application of these modern and efficient concretes is sought, while addressing the mechanical and durability limitations of SCC when exposed to freezing temperatures. The impact of fiber reinforcements in tensile ECC and UHPC layers has also been evaluated by comparing polyvinyl alcohol (PVA) and steel fibers. After 150 and 300 saline freeze-thaw cycles, flexural, compressive, and tensile bond strengths were tested. Microstructural degradation was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) was employed to detect chloride-bound phases. Results showed that composite systems had superior freeze-thaw resistance compared to mono-SCC. Chloride penetration was observed throughout SCC layers but was significantly reduced at bond layers with ECC and UHPC, especially in the UHPC based composites. PVA were more effective than steel fibers in reducing chloride binding and lowering corrosion risk.