Cement-cork mortars for thermal bridges correction. Comparison with cement-EPS mortars performance

The aim of this paper is to demonstrate the advantage of cork-mortars for renderings when compared to EPS-mortars, from a thermal characteristics point of view, namely in steady and unsteady conditions. It was intended to develop specific rendering mortars able to be applied in thermal bridges to reduce con- densation effects and heat transfer in buildings envelopes. The impact of this solution is significant, espe- cially in building typologies as framed reinforced concrete structures. Cement mortars and cement-EPS mortars are used as a reference as their properties are easily recognized compared to cement-cork mor- tars, which are made with by-products from the cork industry. Several studies were made concerning fresh and hardened state behaviour of mortars, namely: rheological and mechanical properties, micro- structure evolution with time and thermal behaviour. For a cement based mortar, different cork dosages (from 0% to 80%) were tested (as sand replacement by mass). Microstructural analyses show that the mechanical properties of cement-cork blends are not only controlled by cork’s low density, but also by interaction of cork extractives with the cement hydration process. Thermal conductivity presents a linear decrease for an increasing cork dosage in mortars. Concerning the effect on thermal delay, cork-mortars seem to behave better than EPS-mortars