Thermal performance comparison of recycled and clay roof tiles due heat radiation by digital holographic interferometry

It is through the recycling process that disposed waste materials could regain a new purpose on their use, take for instance the tetrapak (TM) packaging. This material consists of thermally joint layers of paper, aluminum, and polyethylene. Once recycled, the two latter materials form a new composite named poly-aluminum, which is employed to manufacture roof tiles that serve as environmental protection against solar radiation and rain. This work reports an optical nondestructive comparison study of the surface deformation in poly-aluminum and clay roof tiles exposed to heat radiation. The optical system, based on a sensitive out-of-plane interferometer configuration, records several image holograms from a controlled heat source that raises the temperature on the tile's surface. The retrieved optical phase renders the tiles surface's deformation at three different temperature values: 26, 36 and 46 degrees on a Celsius scale. The results show a greater deformation profile from the poly-aluminum tile compared with the classic clay tile. However, its thermal insulation properties are better than those of the clay roof tile.