Tunable chitosan-alginate capsules for a controlled release of crystallisation inhibitors in mortars

Plasters and renders used in historic monuments are vulnerable to degradation caused by salt weathering. Crystallisation inhibitors (molecules/ions that alter crystallisation) mixed into mortars have shown promising results mitigating damage inhibiting crystallisation, promoting transport the evaporating surface, modifying crystal habit. However, past research suggests easily leach out from mortars, meaning their long-term positive effect is lost. Encapsulation of an inhibitor within a mortar potential solution minimise leaching. Herein, capsules composed polyelectrolyte complex calcium alginate coated chitosan investigated for controlled diffusive release sodium ferrocyanide, known NaCl crystallisation inhibitor. Capsules with varying chitosan-calcium ratios prepared using extrusion dripping technique. The solutions various pH values ranging 7–13 investigated. Results show increasing capsule’s ratio reduces all studied compared pure calcium-alginate capsules. Therefore, can be obtained tuning chitosan-alginate ratio. In future, additional tests will performed find suitable capsule compositions optimising performance when mortars.