Strength related global warming potential of fly ash (+ silica fume) concrete with(out) mass/economic allocation of the by-products' impact

Author(s): P. van den Heede and N. De Belie
Paper category: symposium
Book title: International Symposium on Life Cycle Assessment and Construction – Civil engineering and buildings
Editor(s): A. Ventura and C. de la Roche
Print ISBN: 978-2-35158-127-8
e-ISBN: 978-2-35158-128-5
Publisher: RILEM Publications SARL
Pages: 336 – 343
Total Pages: 8
Language: English

Abstract: From European Directive 2008/98/EC, it is clear that secondary cementitious materials such as fly ash (FA) and silica fume (SF) can no longer be seen as mere waste products. Indeed, a certain environmental impact needs to be allocated to them when performing a life cycle assessment (LCA). This paper presents the results of a probabilistic LCA of concrete with various FA contents (15%, 40%, 50%). To evaluate the influence of strength differences between concrete mixes, a centric loaded concrete column was chosen as functional unit in a cradle-to-gate LCA. To obtain a higher early strength compared to the mix with 50% FA, 10% SF was added to the concrete mix with 40% FA. Partial environmental burdens were assigned to FA and SF using mass and economic allocation. When comparing 1 m³ of each concrete mix with the reference without FA or SF, the global warming potentials (GWPs) of the mixes with 15%, 40% and 50% FA increase above the reference when applying mass (GWP + 24.5%, + 40.4%, + 95.7%) instead of economic allocation (GWP – 1.9%, – 23.9%, – 11.8% when compared to the reference). LCA scores for concrete columns show a substantial benefit of the 10% FA addition due to the strength increase: GWP + 39.4% in case of economic allocation.

Online publication: 2012
Publication Type: full_text
Public price (Euros): 0.00