From spolia to recycling; the reuse of traditional construction materials in built heritage and its role in sustainability today; a review

The reuse of traditional construction materials attests to their high value over the long term. In fact, the practice has always demonstrated the inherent value of traditional raw materials and their products in confronting the issues of sustainability, in the broader sense of preserving resources - material and immaterial - for future generations. Throughout the history of building, the symbolic value of spolia (i.e. the use of ancient architectural elements in new construction) has gone hand-in-hand with the practice of recycling, demonstrating, at various levels, an intrinsic awareness of reuse as a tool for minimizing waste of materials and energy. Today, sustainability is rarely considered from a long-term perspective, and when it is, the approach tends to be from a broad theoretical standpoint. In the past, however, it was a common and necessary aspect of construction management, when the waste of materials was a forbidden luxury. This paper presents a review of the reuse of geomaterials, mainly stone, throughout the Italian history of construction, indicating major examples selected for their value as memorable references, describing common practices from antiquity to modern times, and concluding with a description of the actual state of the art of the practice, based on very recent and outstanding cases.