Design of lightweight concrete with olive biomass bottom ash for use in buildings

The ash generated during the combustion of biomass in electricity generation plants is a waste that has increased considerably in recent years, and whose management constitutes an environmental problem. In this regard, the recovery of biomass bottom ash as a partial replacement of natural materials for use in different civil engineering applications, as well as for the manufacture of construction materials, has been the subject of numerous studies that have shown its technical feasibility. However, for its application in the development of new sustainable materials, with thermal insulation properties, it is necessary to expand our existing knowledge of it. In this study, the use of bottom ash from original and processed biomass bottom ash in the manufacture of lightweight concrete, as a replacement for sand (15%–25%) and expanded clay (25%–35%), has been evaluated. In addition, after subjecting the ash to a grinding process, it was also incorporated into the concrete by replacing cement. The physical, mechanical, thermal and durability properties were evaluated according to regulations and the results showed that the thermal treatment applied to biomass bottom ash improved the mechanical performance of lightweight concrete. Likewise, thermal conductivity was reduced by up to 43%, which allows these concretes to be used as insulating materials in buildings. Therefore, this study shows the possibility of recovering biomass bottom ash in the manufacture of lightweight concrete for use in construction.