This study proposes different manufacturing techniques (manual pelletization, powder pressing, and "shell scaffold") to obtain lightweight clay ceramics containing recovery raw materials. The sintering in an electrical furnace (1000 °C, 1 h processing time) was conducted by traditional firing from room temperature, for pressed and shell-scaffold samples, while the flash heating (i.e., samples directly put at 1000 °C) was used only for the pellets. The porous materials (porosity 40-80%), functionalized with nutrients (K and P) in amounts to confer the fertilizer capability, gave suitable results in terms of pH (6.7-8.15) and electrical conductivity (0.29-1.33 mS/cm). Thus, such materials can be considered as feasible lightweight clay ceramics, with a positive effect on the soil. These findings permit us to hypothesize a potential use in green roofs or in agronomic applications.
Keywords: fertilizer; manual pelletization; porous clay ceramics; pressing; shell scaffold.