Addition of microencapsulated PCM into single layer mortar: physical and thermal properties and fire resistance

Abstract

The energy consumption in buildings has increased in the last years due to the energy demand for thermal comfort. The improvement of thermal properties in building materials is one of the key points to achieve a reduction of the energy demand. Thermal energy storage (TES) is an alternative to save energy that has been investigated extensively in recent years. The addition of phase change materials (PCM) in a material increases its thermal inertia because PCM are able to store and release energy in sensible and latent heat. In this paper coatings used in the outer walls of buildings are studied, in particular single layer mortar. Microencapsulated paraffin PCM is added into the material to improve the thermal properties of the building envelope. The use of PCM combined with thermal insulation can reduce the energy consumption of buildings by absorbing heat gains and reducing the heat flow. Two types of single layer mortar Weber.Therm.Mineral commerzialized by Weber Saint Gobain incorporating different percentages of microencapsulated PCM type Micronal® DS5001 (20%, 10% and 0%) in their formulations are studied in this paper. The main objective of this work is to analyze the effect of PCM addition on the properties of two single layer mortars. Fresh mortar properties, as well as fire behavior, physical, mechanical and thermal properties of hardened mortar have been evaluated. The results show that physical and mechanical properties of single layer mortar are affected by the addition of microencapsulated PCM. Compressive strength decreases 60% with the addition of 20% of PCM in the formulation while the formulation with 10% of PCM has approximately the same compressive strength than a single layer mortar without PCM. The addition of PCM in the formulation decreases in 35% the adherence of the single layer mortar to a concrete surface. The presence of PCM in the mortar formulation worsens the fire behavior, due to the organic, and therefore flammable, composition of Micronal® DS5001. Flammability increases according to the percentage of PCM added. As a general conclusion, physical and mechanical properties of the single layer mortar become worse when the percentage of the added microencapsulated PCM is increased. Nevertheless, an improvement of thermal properties is expected and the quantification will be done that could justify the addition of PCM to some extent.