Sustainable Reuse of Formula Milk Tin Waste for Enhancing Concrete Confinement

Concrete columns play a vital role in structural systems due to their ability to resist axial and lateral loads. Enhancing column performance through confinement has been widely studied, particularly using steel tube confined concrete (STCC). In parallel, the growing amount of metal waste highlights the need for innovative and sustainable reuse strategies. One type of waste with a geometry similar to steel tubes is formula milk tins, which are commonly discarded household products. This study investigates the potential use of formula milk tin waste as external confinement for concrete specimens. Concrete cylinders confined with formula milk tins (13 cm in diameter and 16 cm in height) were compared with standard cylindrical specimens (15 cm × 30 cm). Two types of confinement were examined: plain tins and corrugated tins. All specimens were prepared using K200-grade concrete and subjected to two curing methods, namely water curing and air curing, for 28 days. Compressive strength tests were conducted in accordance with relevant standards, and correction factors were applied to account for non-standard specimen dimensions. The results show that specimens confined with formula milk tins exhibited higher compressive strength than unconfined specimens. Corrugated tin confinement provided the greatest strength enhancement, improved stiffness, and more controlled failure behavior. While water curing resulted in higher compressive strength than air curing, the confinement effect was found to be more influential than the curing method. These findings demonstrate that formula milk tins have significant potential as an alternative external confinement material for simple concrete columns, offering both structural performance improvement and a sustainable solution for reducing metal waste.