Thermal Expansion/Energy Storage Characteristics of EAF-Slag Mortars for Passive Solar Energy

This study investigates the thermal expansion and absorption characteristics of electric-arc-furnace slag (EAF-slag) mortars and Portland cement (PC) mortars with river sand. The aim is to compare the properties of EAF-slag mortars, an innovative recycled material, with those of PC mortars, a commonly used material in civil construction, for passive solar energy storage in roofs, facades, and pavements. ASTM C531 standard was followed for preparing the samples, with PC samples undergoing hydration curing and EAF samples undergoing accelerated carbonation. After curing, the samples were placed in an oven at 60 ºC for 24 h. Results show that the thermal expansion of EAF-slag mortars was 0.11 cm, while that of PC mortars was 0.05 cm. The linear coefficient of thermal expansion for EAF-slag mortars was 18.16 × 10–5 (cm/cm °C), and that of PC mortars was 8.30 × 10–5 (cm/cm °C). At room temperature of 22 ºC, the EAF-slag mortar samples had a temperature of 20.9 ºC, while the PC mortar had a temperature of 18.8 ºC. After being removed from the oven, the EAF-slag mortar sample had a temperature of 57 ºC, while the PC mortar sample had a temperature of 51.7 ºC. The EAF-slag mortar sample maintained a higher temperature than the PC mortar sample. These results suggest that EAF-slag mortars have great potential for passive solar energy storage in constructing pavements, facades, and roofs.