Construction and demolition inert materials: chemical-mineralogical characterization and hypothesis for their reuse.

Building activity is currently demanding noticeable amounts of natural inert materials, such as gravel and sand, usually provided by natural sediments. The extraction of sediments from rivers, for example, modifies river-profiles and their equilibrium as well as quarrying activities from paleo-river deposits could induce environmental problems, as the modification of hydrological and hydrogeological framework of the interested area. Moreover quarrying inert materials from rocky formations in hilly/mountainous areas is perceived as dangerous for the environment, as it alters the landscape and potentially triggers stability problems. The use of recycled aggregates is promoted by the EU which, in the framework of an environmental protection and waste management policy, has provided guidelines for common strategies for a correct re-use of construction and demolition (C&D as proposed by Poon et al., 2001) (DG ENV. E. 3, 2000). With the introduction of a specific waste legislation, with regulations and directives, in many parts of world, a significant move towards the sustainable management of C&D inert materials is becoming a legal requirement. In response, different sectors of the construction industry are undertaking various initiatives to minimise waste generation and improve the management of C&D waste to maximise economic and environmental benefits, generally by placing emphasis on increasing recycling for reuse. As for the Italian situation, currently the legislation (D.L. 152/06) is encouraging the re-use of C&D inert materials but the re-utilisation of these materials is hampered by the scarcity of suitable plants for processing, as a result this resource is used as a lower quality materials for low grade application (i.e. road sub-base). In this study, different grain-size fractions, obtained by a grain-size sorting, from a C&D processing plant in Rovigo (NE Italy), were investigated through X-ray fluorescence (XRF) and X-ray diffractometry (XRD) analyses, in order to evaluate their chemical and mineralogical composition, assisting in the development of improved recycling methodologies. This study indicates that, through an opportune crushing and sorting operation for C&D material, it is possible to obtain grain-size fractions with roughly homogenous chemical and mineralogical composition on each fraction. The homogeneity of the materials can be considerably improved if a careful differentiation takes place during the initial stages of C&D production (Poon, 1997; Poon et al. 2001). The finer fractions could be used for hydraulic mortar preparation only if the fraction of bricks, tiles and terracotta is prevalent, providing material with pozzolanic attitude (Baronio et al., 1997; Corinaldesi et al., 2002; Zendri et al., 2004). These fine recycled fractions could also be used in high grade application (i.e. starting materials for ceramics) requiring an industrial treatment (e.g., sintering process). Similarly, it could be also possible to reuse them in cement preparation, after suitable mixing with lime and subsequent calcination process. References: -Baronio, G., Binda, L., Bombardini, N., 1997. Construction and Building Materials 11, 33-40. -Corinaldesi, V., Giuggioloni, M., Moriconi, G., 2002. Waste management 22, 893-899. -D.L. 152/06-Decreto Legislativo 152/06: Norme in materia ambientale, parte IV. -European Commission, Directorate - General Environment, DG ENV. E.3, 2000. Management of construction and demolition waste. Working document No. 1, pp. 1-26. -Poon, C.S., 1997. Waste Management and Research 15, 561-572. -Poon, C.S., Yu, A.T.W., Ng, L.H., 2001. Conservation and Recycling 32, 157-172. -Zendri, E., Lucchini, V., Biscontin, G., Morabito, M., 2004. Applied Clay Science 25, 1-7.