MASS HYDROPHOBIZED LIME CEMENT MORTAR AS TOOL FOR PREVENTIVE CONSERVATION

Water represents without any doubt one of the most important degradation factors for a wide typology of materials like plasters, mortars, concretes, bricks and natural stones [1]. The degradation processes due to the water action towards architectural materials has been over time a problem with an increasing importance in the last years, as a consequence of the intensification of precipitations and world climate changes. The damages caused by water to buildings and architectures are often serious, with high costs for the reparation of materials and structures which are not well protected. Solutions able to prevent and limit this problem should be seen and studied as a sustainability tools for the protection of new and old buildings. This research deals with the study and development of in-mass-hydrophobized rendering mortars, which can be applied for the protection of building facades. Previous studies have focused on in mass water-repellent mortars, showing that hydrophobic compounds can be mixed to different binders and aggregates to obtain mortars whose water-repellent effectiveness depends most on the binder system chosen [2-5]. In this research lime cement mortars, which have not been deeply investigated yet, were taken in account. Integral water repellent lime cement mortars were prepared using different hydrophobic compounds. Calcium stearates, zinc stearates, powder silanes, liquid silanes were added to lime cement mortars. The influence of the additives on the setting and structure of mortars were investigated as well as the effectiveness of these agents in protecting the mortars against damages caused by the water action. Instrumental techniques such FT-IR and XRD were used in order to understand the chemical-physical interaction between agents and cement mortars. MIP analysis, ultrasonic measurements, water absorption tests and contact angle measurements were carried out to investigate the effectiveness of the water-repellent additives in hydrophobizing the final mortars. Workability variation of fresh mortars and a slight influence on the hydration times and products were observed. The water-repellent effectiveness changed with the additive chosen as well as the structure and the water vapor permeability.