Performance Assessment of Curing Techniques on Pozzolanic Concrete

Abstract

The strength development of Portland cement concrete primarily results from the formation of ettringite and calcium silicate hydrates during hydration, which requires sufficient moisture. Effective curing is essential to maintain the moisture needed for this reaction, significantly influencing compressive strength. As such, researchers continue to explore optimal curing methods. Additionally, the use of pozzolanic materials as partial replacements for ordinary Portland cement has gained interest, though their hydration and strength development are also affected by curing techniques. This study investigates the impact of four curing methods i.e. ponding, sprinkling, covering with an impermeable membrane, and chemical curing on the strength development of five pozzolanic concretes incorporating groundnut shell ash (GSA), coal bottom ash (CBA), locust bean pod ash (LBPA), wood ash (WA), and metakaolin. Sixty cylindrical specimens (150 mm × 300 mm) were prepared, with three samples per curing method for each pozzolan, tested at 3, 7, 14, and 28 days. The results show similar strength across all curing methods at 3 days. However, as curing continued, significant strength differences emerged. Chemical curing consistently produced the highest compressive strength due to its superior moisture retention, followed by ponding, membrane covering, and sprinkling. Regardless of pozzolan type, strength increased with extended curing periods. The study concludes that adequate curing time is vital for strength development in pozzolanic concretes. Among the methods evaluated, chemical curing is the most effective, followed by ponding and membrane methods, with sprinkling being the least effective. These findings offer practical guidance for selecting suitable curing techniques to optimize pozzolanic concrete performance under standard conditions.