Polyvinyl Alcohol-Modified NHL-Based Mortars for the Restoration of Historical Buildings

This study investigates the effect of polyvinyl alcohol (PVA) on the performance of natural hydraulic lime (NHL)-based repair mortars used in historical building restoration. Mortars were prepared with varying PVA dosages (0.25%, 0.5%, 0.75%, and 1.0%) to evaluate their impact on physical, mechanical, and durability properties, including setting time, strength, water absorption, shrinkage, and resistance to freeze-thaw and sulfate attack. The results demonstrate that PVA significantly enhances bonding strength, reduces water absorption, and improves durability, with optimal performance observed at a 0.5% PVA dosage. Microstructural analysis showed that PVA forms a cohesive film, reinforcing the mortar's structure. These findings suggest that PVA can enhance the performance of NHL-based mortars, offering significant potential for historical building restoration, particularly under challenging environmental conditions.