Hydrophobic lime based mortars with linseed oil: Characterization and durability assessment

Linseed oil was added to lime and lime metakaolin mortars in order to impart hydrophobic properties and investigate its resistance to weathering agents involving water transport. Different properties of the mortars with 6 months of age were evaluated: open porosity, pore size distribution, water absorption by capillarity, mechanical strength, carbonation reactions, microstructure and durability assessed by testing the resistance to sodium chloride accelerated ageing test. Significant durability improvement of both lime and lime metakaolin mortars enriched with linseed oil was achieved: remarkable capillarity reduction and consequently higher resistance to NaCl cycles. Linseed oil had a different effect on the two studied mortars: mechanical strength was slightly reduced for lime and slightly raised for lime metakaolin. The mechanism for the durability improvement was found to be related to the modification of the chemical structure rather than on the alteration of the physical properties of the mortars.