Conference article

The moisture sorption properties of fly or bottom ash and their application prospect as evaporative coolers of roof surfaces were studied. nitially; samples were characterized through techniques like elemental analysis; x-ray diffraction; thermogravimetry; reflectance measurements and water vapor adsorption isotherms. Moreover; the water adsorption properties and the associated temperature variations were determined in a specific wind tunnel with controllable environmental conditions. The adsorption isotherms were of type III indicating hydrophobic materials with low water vapor adsorption. However; all samples were capable of lowering their surface temperatures due to water evaporation and the release of the latent heat. The maximum differences in temperature increase under simulated solar irradiation between fly ash and concrete were 3.8; 4.1 and 6.4 °C for the surface; middle and bottom; respectively of 3 cm material thickness. The toxicity assessment of materials implication in buildings roofs was performed by radioactivity and metal leaching experiments with rain water. According to the results; mixing of fly ash with either an inert material like soil or a green roof material or multifunctional nanocomposites is proposed in order to minimize its environmental impact.

Evaporative cooling; Solar cooling; Water vapor sorption; Fly ash; Lignite