In the two last decades, world production of pig iron and steel has undergone a significant increase. In 2018, 1252.87 and 1806.46 million tons of pig iron and steel, respectively, were produced as compared to the 575.78 and 809.94 million tons of 2000. Consequently, the amount of the different types of slags deriving from these production processes has also increased considerably. In relation to the principles of sustainability and circular economy, the available literature suggests several possible reuses for these slags (bituminous conglomerates, hydraulic engineering, metallurgy, fertilizers, etc.). This paper aims to provide an overview of the iron and steel slags production and their reuse in concrete (for example as replacement of cement, fine or coarse aggregates). The characteristics of slags are analyzed in terms of chemical, physical, and mechanical properties. Mechanical and durability tests (both from material and structures point of view) carried out in the different studies and research are shown as well. Particular attention was devoted to electric arc furnace slags (EAF) since they are the most produced in Italy. Based on this deep literature review, the gaps that still require further studies have been identified and discussed.

Italian production of construction and demolition waste (CDW) reached about 62 million tons in 2022. Despite the high recovery rate (79.8 percent), most of the treated CDW is stored waiting to be used. In most cases, the recycled aggregates (RAs) resulting from CDW processing turn out to be of low quality and mostly destined for “low-grade” applications (road and railway pavements, civil engineering works, backfills or environmental recoveries). The use of RAs in so-called "high-grade" applications, such as concrete production, is unfortunately limited today by several factors, including the type and origin of RAs, their mechanical properties (often lower than those of natural aggregates) and the potential release of contaminants. In fact, concrete production requires an RA that has similar performance to natural aggregate. This is the main objective of the Life CDW Circle project, co-funded by the European Union and presented in this paper, which aims to achieve total recycling and use of treated CDW, thanks to an innovative sorting technology that allows the separation of different aggregate fractions (aggregates, bricks, tiles, etc.) and the production of RAs with high added value. During the experimental activities, the resulting RAs will be characterized and used for concrete production. After the experimental phase, the project partners will develop appropriate business models, creating an ecosystem with sector stakeholders. The aim of the paper is to provide an overview of CDW and RAs production and use in Italy. In addition, the new Life CDW Circle project structure and objectives will be presented.