The influence of a microencapsulated phase change material (PCM), a lightweight aggregate (LWA) and cellulose fibers on the behavior of cement-lime mortar was investigated. Lightweight aggregates and cellulose fibers were added in order to reduce thermal conductivity. PCM in two different amounts, 10% and 20%, was included to increase thermal inertia of mortars, taking advantage of its heat storage capacity. An experimental program was carried out to assess the effect on physical, mechanical and thermal properties of the different additions and combinations. Thermal conductivity of mortars with PCM at solid and liquid states were measured and Differential Scanning Calorimetry (DSC) was used to evaluate mortars’ enthalpy.

Twelve cement-lime mortars designed for rendering applications, were studied and the experimental results were compared. It was observed that the type and amount of component affected physical, mechanical and thermal mortar properties. Lightweight aggregates increased porosity while reduced strength and thermal conductivity. Cellulose fibers did not modify significantly mortar properties. PCM increased mortar enthalpy while acted as a filler, reducing porosity and strength. However, enthalpy was not linearly related only to the amount of PCM and also depended on mortar composition. LWA increased the enthalpy of PCM cement-lime mortars.