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CONCRETE TECHNOLOGY24 CPI %u2013 Concrete Plant International %u2013 4 | 2025 www.cpi-worldwide.comThe cement and concrete industry is a key enabler of the European Union%u2019s (EU) ambitions for sustainable growth, innovation, and the transition to a climate-neutral economy. Aligned with these objectives, the HORIZON-funded AshCycle project is pioneering the development of next-generation cement mixes and concrete products by valorising underutilized ash streams %u2013 specifically those derived from wood biomass and sewage sludge. Through this innovative approach, AshCycle is unlocking new pathways for circular resource use in construction, advancing both climate and environmental goals within the EU Green Deal framework.As one of Europe%u2019s most resource- and energy-intensive sectors, cement manufacturing is at the heart of the EU%u2019s transition toward a climate-neutral and circular economy. Recognized in the European Green Deal [1] for its strategic importance across multiple value chains, the industry plays a crucial role in realizing sustainability targets. Its close link to the construction sector also positions it as a key driver in the implementation of the Circular Economy Action Plan. Meeting future demands and sustainability targets will require significant investment in research, the piloting of innovative technologies, and their widespread adoption %u2013 particularly within an industry traditionally characterized by conservative practices and long innovation cycles. While innovation remains essential, the European cement industry has already taken important steps toward decarbonization, achieving approximately a 15% reduction in specific CO2 emissions since 1990 [2]. Continued progress can be supported by expanding the use of blended cements with lower clinker content or by developing alternatives to traditional clinker. On the concrete side, environmental impact can be further reduced by incorporating secondary raw materials and mineral admixtures, many of which originate from industrial by-products. Secondary materials have long been utilized in cement and concrete production, with coal combustion ash (CFA) being one of the most established examples. However, as the European Union moves away from non-renewable energy sources, the availability of such by-products is expected to decline. In response, new secondary resources are gaining traction, including ash from wood biomass combustion and the thermal treatment of municipal solid waste or sewage sludge. These emerging materials offer significant potential for further integrating circular economy principles into the cement and concrete sectors, advancing the EU's goals of sustainability and resource efficiency. In this context, the HORIZON-funded AshCycle project [3] is pioneering the development of innovative cement mixes and concrete products by incorporating these new ash sources %u2013 wood biomass ash (WBA) and sewage sludge ash (SSA) %u2013 thereby advancing sustainable practices within the sector. These innovative materials not only provide a solution to material shortages but also align with the EU%u2019s sustainability goals, supporting the transition to a more circular and resource-efficient economy.Waste ashes from incineration processesThe diminishing availability of traditional supplementary materials, such as CFA, necessitates the investigation of new materials for the cement and concrete industry. Concurrently, ash produced from the thermal treatment of municipal waste, sewage sludge, and biomass remains underutilized, primarily due to technical limitations and the lack of comprehensive regulatory frameworks and standards. In the European Union, over 250 million tons of municipal waste are generated annually, of which approximately 25% by weight is thermally treated [4]. As landfill disposal becomes progressively restricted (currently ~23% by weight), the proportion of thermally treated waste is expected to increase, leading to higher volumes of ash residues. The thermal treatment of waste generates a substantial amount of ash (~17 Mt/year), which contains a range of valuable metals, including aluminium (16.5 kg/t), steel (15.4 kg/t), copper (5.0 kg/t), zinc (1.6 kg/t), lead (0.2 kg/t), silver (0.01 kg/t), and trace amounts of gold (0.0005 kg/t) [5]. The total content of rare earth elements in these ashes is approximately 100 mg/kg [6]. Bottom ash, which accounts for 20-30% by weight of the total residue, often contains refractory materials such as glass and ceramics [4]. Despite its potential, the recycling and utilization of ash Utilizing incineration ashesAdvancements in cement and concrete productionn Nina %u0160tirmer, Jelena %u0160antek Bajto, Ivana Carevi%u0107, Ivana Banjad Pe%u010dur, Marijana Serdar and Marija Mende%u0161, University of Zagreb, Faculty of Civil Engineering, Croatia