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

Abstract

Material 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. Keywords: bulk nonmetallic mineral building materials circular economy continuous MFA (C-MFA) industrial ecology material flow analysis (MFA) recycling Supporting information is linked to this article on the JIE website Conflict of Interest Statement: The authors have no conflict to declare.

Taking the Circularity to the Next Level: A Special Issue on the Circular Economy

“…Schiller and colleagues (), in their work on the German building sector, propose a new MFA methodology for directly linking material inflow and outflows to the use phase of buildings. This is applied to bulk nonmetallic mineral building materials in the German building stock, with a focus on aggregate recycling from concrete building elements.…”

The State of the Art of Material Flow Analysis Research Based on Construction and Demolition Waste Recycling and Disposal

“…Schiller et al [49] presented a continuous MFA concept and a conceptual framework of continuous material flow analysis, which included traditional MFA and a reverse flow. This reverse flow includes the capturing of high-quality waste in deconstruction processing, the processing captured waste into recycling aggregates, and the mixing of these aggregates to new products.…”

“…This reverse flow includes the capturing of high-quality waste in deconstruction processing, the processing captured waste into recycling aggregates, and the mixing of these aggregates to new products. Schiller et al aimed to assess and quantify the entire building material cycle by considering the conversion of bulk nonmetallic mineral into recycled aggregates [49].…”

Quantification of anthropogenic metabolism using spatially differentiated continuous MFA

“…Here, three additional modules, namely "capture", "processing" and "admixture" (Fig. 1), constitute the methodological expansion of the C-MFA according to [35]. These new modules encompass the various steps involved in extracting the relevant waste fractions and their processing into recycled products (see subsection 2.6) as well as legal and technical regulations specifying the permitted uses of such products as building materials (cf.…”