Ecologically Friendly Building Materials: A Case Study of Clay–Ash Composites for the Efficient Management of Fly Ash from the Thermal Conversion of Sewage Sludge

Abstract

The European Union’s initiative to reduce carbon dioxide emissions has paved the way for the exploration of innovative building materials that are environmentally friendly and meet all requirements of durability and strength. These criteria can be met by combining natural resources used in the production of building materials with waste materials that would otherwise be landfilled, having a negative impact on the environment. This study focuses on such materials and presents the results of recent research conducted at the Warsaw University of Life Sciences. The aim was to develop a new generation of materials fully compliant with the principles of the circular economy and sustainable development. Simultaneously, these materials should have no adverse effects on human health and be strong enough to carry the required loads. This study proposes the combination of a natural raw material—in the form of clay—with fly ash from the incineration of sewage sludge to produce a new generation of materials. Several samples were prepared using fly ash from two sources and then were fired at 950 °C. The resulting composites underwent physico-chemical and strength tests. These tests not only confirmed the high strength and durability of the obtained product but also the neutralization of the heavy metals originally present in the fly ash.