Environmental assessment in the building materials industry: How are the results of life-cycle-assessment (LCA) for concrete influenced by technology and regulations?

Abstract

In the building material industry, sustainability concerns are dominated by the role of raw materials, especially in the production of cement (e.g. fuels) and concrete (e.g. recycled aggregates). As raw materials become increasingly scarce worldwide, this an accelerating challenge faced by both individual companies and countries. To investigate the environmental impact of the building materials industry, a widely accepted tool is the Life Cycle Assessment (LCA). Although LCA is frequently used to evaluate the sustainability of building materials, recent studies show that the interpretation of LCA results can be difficult in sustainable construction due to ambiguity of underlying assumptions.In the ongoing research project "Co-Evolution of Business Strategies in material and construction industries and public policies" we analyse how the results of LCA for concrete building materials are influenced by the production technology, regulations (e.g. waste treatment), socio-technical settings (e.g. energy supply systems) and methodological choices in LCA. Our results are based on an intensive literature review and scenario analysis based on a model of the concrete product system using LCA.It shows that differing results of LCA studies can be accounted to variations of cement content, clinker to cement ratio or share of alternative fuels in the fuel mix in cement production. Alternative methodological choices in LCA influence the results for Global Warming Potential GWP when carbon uptake during service life and recycling of concrete is considered (shift of perspective from cradle-to-gate to cradle-to-grave). Allocation rules for SCMs (e.g. ground granulated blast furnace slag GBFS) or alternative fuels also have a relevant effect on LCA results for GWP and Cumulative Energy Demand CED.