Development of a depletion indicator for natural resources used in concrete
Résumé
The objective of this study is to propose a reliable and clear indicator that could assess the present state of depletion of local bulk resources in different regions. The article argues that indicators commonly used to assess resource consumption in the Life Cycle Impact Assessment (LCIA) are not fully adapted to the particular sector of concrete industry. Most impact assessment methods assume that at a global world wide scale, the stock for bulk resources, such as the sand and gravel used for concrete manufacture is so important that it could be considered as unlimited. This is true on global scale, but not on a regional scale. Here we assume that the regional scale is a pertinent scale upon which to base resource extraction policies, as concrete and its constituents are not transported over long distances. Therefore we propose a new method to calculate resource consumption impacts that uses a new assessment of the stock of resources. The potential accessible resource stock within one territory is calculated rather than the ultimate global resource availability. This potential stock is evaluated by the study of the temporal evolution of importation over consumption ratio for a given specific material. Some results for United States of America and for France are presented. It is shown that the impact on resource consumption for concretes made with aggregates coming from different places is significantly different using the new indicator. It was not possible to highlight this with previous LCIA indicators. Finally the limit of this indicator application is discussed.