Continuous Material Flow Analysis Approach for Bulk Nonmetallic Mineral Building Materials Applied to the German Building Sector

Abstract

SummaryMaterial flow analysis (MFA) is a helpful tool to understand and develop the circular economy. There exist a number of MFA models to depict inflows and outflows of bulk nonmetallic mineral building materials, which are, in fact, the largest flows in terms of tonnes. However, until now such models have not attempted to directly link inflows and outflows. In order to achieve such closed loops, it is necessary to consider the qualitative aspects of inflows and outflows as well as quantities. The technical possibilities of recycling are, in fact, determined by both the quality and quantity of materials. This requires the integration of knowledge on process engineering, the technology of waste management, and indeed the structure of buildings. The article integrates these aspects within a continuous MFA approach (C‐MFA), which is able to analyze and quantify the entire material cycle of bulk nonmetallic mineral building materials by considering the use of recycled aggregates in concrete building elements. This is achieved by methodological expansions that take into account qualitative aspects with regard to outflows and inflows. The approach is applied to questions of high‐quality recycling within the German building stock. The continuity of construction and demolition waste output and secondary material input is realized by integrating the process steps required to capture high‐quality waste in the course of building demolition, material processing of the material to produce recycled aggregates, and admixing of the aggregates to produce new concrete used in buildings. This can be extended by considering the inflows and outflows of other sectors, for example, the infrastructure sector. The main outcome is an extended C‐MFA approach that enables quantification of sectoral as well as, in principle, intersectoral material loops of bulk nonmetallic mineral building materials while uncovering potentials to save natural resources as well to better exploit anthropogenic resources.