The thermal mass of concrete within a building can be used as an energy storage system and hence reduce the demand on the auxiliary heating and cooling systems in the building. The heat storage capacity of concrete can be enhanced by adding phase change materials (PCMs) which provide a high latent heat storage capacity. However the addition of PCM to concrete reduces the conductivity of the concrete due to the low conductivity of the PCMs. This hinders the efficient utilisation of the additional heat storage capacity provided by the PCM.
It is generally understood that the use of ground granulated blastfurnace slag (GGBS) as a partial cement replacement results in a denser cement paste which, for a given aggregate type, increases the conductivity of the concrete. The aim of this study was to determine if the use of GGBS influences the thermal mass behaviour of a PCM-concrete.
Two types of PCM-concrete panels were manufactured. Firstly microencapsulated paraffin was added to fresh concrete during the mixing process. Secondly butyl stearate was vacuum impregnated into lightweight aggregate which was then included in the concrete mix. Half of the samples contained 50% GGBS cement replacement and consequently the effect of GGBS on the thermal performance is reporte
