Effect of water immersion on bond strength of vinyl acetate ethylene-modified ceramic tile adhesive

In this study, the bond strength and failure mechanism evolution of ceramic tile adhesive (CTA) after water immersion are investigated, focusing on vinyl acetate ethylene (VAE) modification effects under dry and water curing conditions. By comparing VAE-modified to unmodified CTA, the various parameters were evaluated, including bond strength, cohesion, interfacial adhesion and dimensional variations. The results indicated that VAE-modified CTA had higher bond strength than unmodified CTA because VAE boosted the degree of hydration at 7 days, and improved interfacial adhesion more than cohesion under 7 days of dry curing, inducing predominant cohesion failure. Following 2 days of water immersion, sharp declines in both properties (greater for interfacial adhesion) were caused, shifting the failure mode to interfacial adhesion failure (A-F) due to internal stresses from differential dimensional variations. After 21 days of water immersion, enhanced cement hydration contributed more to an improvement in cohesion, thereby increasing the occurrence of A-F. Subsequent re-drying for 48 h allowed the bond strength of VAE-modified CTA to recover to 180% of its value post-immersion, benefiting from the water resistance of the VAE polymer film.