Development of an Integrated Durability Assessment Methodology of Thermal Mortars Applied in Multi-layer Systems

A gap in the durability assessment of thermal mortars applied in multi-layer systems was observed. The existing standardisation for the durability assessment of hardened mortars does not include a consistent evaluation of thermal coatings applied in multilayer systems, which motivated the development of a new durability assessment methodology. The determination of the physical, hygrothermal and mechanical properties allowed deepening the knowledge of thermal mortars, contributing to develop more reliable simulations. The existing durability methodologies applicable to one-coat mortars and those applicable to thermal multilayer systems (such as ETICS - External Thermal Insulation Composite Systems) are suitable to be adapted to thermal rendering and plastering systems since they present some similar characteristics. The methodology takes into account the material characteristics and specific requirements, such as the application and climatic conditions. The knowledge of these parameters allows the definition of representative accelerated ageing cycles of the relevant degradation mechanisms. The combination of existing procedures with hygrothermal simulation allowed the development of accelerated ageing cycles, taking into account the European climatic context. The existing procedures allowed analysing several degradation mechanisms, but the fixed parameters are not transversal to different climates. The developed methodology allows a realistic durability evaluation since the ageing cycles are adapted to thermal mortars and real climate conditions, contrary to the existing standardised procedures.