Reducing the risk of thermal cracking in cementitious materials by means of encapsulated phase-change materials

Nowadays, when building new sustainable constructions with cementitious materials, energy efficiency becomes of larger significance especially in terms of global warming. The thermal insulation is hereby of utmost importance and the end-user wants a high and efficient thermal comfort. Concrete, having a high thermal mass, should and can be optimized in terms of heat capacity. Encapsulated Phase-Change Materials (PCMs) could be used for this purpose. PCM-mortars expand the thermal comfort in buildings. They store the heat during hot periods and release their stored heat during colder periods. This leads to a more gradual temperature feeling in buildings, increasing the experienced thermal comfort. PCMs can reduce energy consumption in buildings due to their thermal energy storage capability. In this paper, the effects of PCMs on the fresh properties, strength and thermal properties of mortar were studied. PCMs do not impair workability but they delay setting and reduce the strength, especially when high amounts (more than three mass percentage of cement weight) are added to the mortar. But the strength suffices for most concrete applications. Furthermore – as a proof of concept – the influences on the thermal properties and thermal cracking of insulated concrete sandwich panels were studied. Different PCMs with varying melting points of paraffin were hereby studied. PCMs reduce thermal strains due to their heat storage and thus counteract thermal cracking. They are innovative and promising materials to be used in future applications of civil constructions to promote thermal comfort and to reduce the risk of thermal cracking.