## 5 Potential Drivers, Barriers, and Prospects for IBA Use  
Globally, the demand for natural resources has been widely increasing in recent decades, causing environmental pressure. It is estimated that, without new policies, the global use of resources will grow from 89,000 Mt in 2017 to 167,000 Mt in 2060 [98]. Particularly for aggregates, the consumption in western countries plays a major role in the exploitation of non-renewable natural resources, and the annual production of aggregates is about 2500 Mt at the EU level [99]. In the EU, there has been a growing concern for using wastes as resources towards a circular economy approach in which natural resources must be managed in a sustainable manner [100]. In fact, one of the objectives of the European Green Deal presented by the European Commission is to enhance the efficient use of resources through the shift to a circular economy paradigm [101]. In particular, since high amounts of IBA have been generated in the EU (and other countries with incineration), it seems very relevant to find solutions to manage it in a sustainable manner. As noted above, the utilization of IBA has been studied and applied to substitute raw materials. According to Valorsul (2021b) [99], the artificial aggregate produced with IBA can be used in the framework of the Portuguese Decree-Law No. 178/2006 establishing that, whenever technically feasible, at least 5% of recycled materials or those that incorporate recycled materials must be used in public construction works. Moreover, the use of IBA in landfill cover makes it possible to avoid the extraction of soil for the purpose, greatly avoiding the associated environmental impacts linked to the consumption of natural (finite) resources, their transportation, and the consequences of the extraction on vegetation, fauna, water quality, landscape, etc. The European Green Deal also intends to restore/protect biodiversity and cut down on pollution [101]. According to the waste management hierarchy established by the WFD for the EU member states, disposal in landfills should be the last option for waste management. Diverting waste from landfills must be a priority due to inherent constraints, namely extended aftercare periods, limited landfill space, and high potential environmental impacts, e.g., emissions of greenhouse gases (CH\({}_{4}\) and CO\({}_{2}\)), pollution of groundwater and soil, odor emission, and loss of potentially recyclable resources [101; 11; 59; 102]. Proper and environmentally sound utilization of anthropogenic resources like IBA contributes both to the circular economy and the reduction of the amount of waste landfilled and related impacts. Furthermore, diverting waste from landfills provides economic benefits, since landfill costs, taxes, and costs of mining raw materials are prevented [103]. According to [PERSON] et al. (2020) [15], the use of the mineral fraction of IBA could reduce the volume of non-hazardous waste landfills in the EU by 5 million m\({}^{3}\) or 7-8 \(v/v\) % annually. However, \"waste\" classification leads to constrictions on its management and utilization. The development of \"end-of-waste\" criteria according to Article 6 of the WFD could be relevant, possibly favoring reuse. This status is presented in the WFD for certain specified waste that is subjected to a recovery operation (including recycling) and complies with certain criteria for becoming a product, including (i) the common use for specific purposes, (ii) the existence of a market or demand, (iii) the fulfillment of the technical requirements for the specific purposes and the compliance with legislation and standards, and (iv) the avoidance of overall adverse environmental or human health impacts. This status may be given at the EU or national level or be considered case by case within EU member states. There have been complex discussions in the EU on how to comply with the WFD conditions, especially those linked to the protection of human health and the environment. As a result, the status has not been achieved yet at the EU level.