The material dimension of urbanization: flows and stocks of construction materials in Ile-de-France region
Construction materials are the largest flows entering urban areas after water, while they constitute the top waste deposit. The relation between these material flows and urbanization processes has receive little attention and it is the object of this study. Work was conducted in collaboration with the Regional and inter-departmental directorate for the environment and energy Ile-de-France, responsible of the quarries regulation plan, and the Regional council, which is in charge of the C&D waste management plan. This research contributed to methodological improvement for the quantification and localisation of contruction material flows and stocks at regional scale with the case study of Ile-de-France region. Il demonstrates that that the primary and secondary resources available and extracted are close in terms of quantity. However, the utilization rate of the secondary resources is significantly lower than those of primary resources due to normative and regulatory frameworks. In 2013, the mobilization of construction materials from Ile-de-France was mainly generated by the process of urban renewal. This renewal causes major demolition and reconstruction, but it is also carried by urban densification and requires the import of external materials. In addition, the renewal of built works is strongly related to spatial configuration. A projection of material flows up to 2032 shows that achieving the targets for housing construction defined in regional master plan (SDRIF) would lead to a sharp increase in the import rate of materials. This observation calls for alternative public actions aiming at better management of urban resources.