Thermal properties of lightweight concrete incorporating high contents of phase change materials

This research investigated the latent heat and energy storage of lightweight concrete containing high contents of phase change material (PCM) (up to about 7.8% by weight of concrete). PCM – Polyethylene Glycol (PEG) with a fusion temperature of approximately 42–46 °C was impregnated into porous lightweight aggregates up to 24% by weight. The PCM aggregates were then used to replace normal lightweight aggregate at a rate of 0, 25, 50, 75 and 100% by volume. The samples were subjected to series of experiments such as compressive strength (EN12390-3 2002), flexural strength (ASTM C78), thermal conductivity (ASTM C518) and the thermal storage of phase change materials examined using a heat flow meter apparatus (ASTM C1784) at the age of 28 days. Results show that the existence of PCM aggregates affects both mechanical and thermal properties of concrete to different degrees. The mechanical properties appear to improve with increasing PCM aggregate content. For thermal properties such as thermal conductivity and specific heat, the state of the PCM (liquid or solid state) as well as the testing temperature during the test, show significant influence on the obtained results. The latent heat was found to increase proportionally with the increasing PCM aggregate replacement rate.