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TECHNICAL PAPER

lIFE CYClE ASSESSMENT

AND ENVIRONMENTAl

DISTuRBANCE INDICATORS

TO EVAluATE ThE

SuSTAINABIlITY OF

CONCRETE MIX DESIGNS DAmAn K. PAnEsAR, KARInA E. sETO,
CAmEROn J. ChuRChILL, AnD
RunxIAO ZhAng

[3]
Abstract cycle” , is a useful way to model the complex processes that
are included in the life cycle of a concrete product, and can also
Life Cycle Assessment (LCA) is applied to develop a rigorously assess different mix designs. There are four stages in
methodology for calculating Environmental Disturbance an LCA, which guide the structure of this paper: i) Goal and
Indicators (EDI) for six concrete mix designs of varying Scope Definition, ii) Life Cycle Inventory, iii) Life Cycle Impact
constituents (general use cement, limestone cement, and Assessment, and iv) Interpretation.
supplementary cementing materials). The objective of the study
is to quantify the sustainability of concrete mix designs by LCA Usually, the scope of concrete material LCAs is limited to
and to understand the interplay between cementitious material ‘cradle-to-gate’ analysis (i.e. as in literature [4, 5, 6] ). This means
selection, weighting schemes applied to four environmental that the scope is limited to the production of either cement or a
impacts and transportation distance (worst and best case) specific concrete product. Less commonly, LCAs may be ‘cradle-
scenarios. The results reveal that selection of cementitious to-grave’, which includes all life stages, or ‘cradle-to-cradle’,
materials has the greatest effect on the EDI in comparison to the which includes the recycling of all materials at the end of life of
weighting schemes and transportation scenarios, in this study. a product. There has not been a full LCA on concrete materials
for structural applications that has focused on the Canadian
Keywords: Concrete, Functional unit, Limestone cement, Life context, or more specifically on the province of Ontario.
cycle assessment, Supplementary cementing material.
Typically, the upstream profiles of admixtures and supplementary
cementing materials (SCMs) are not included within the scope of
1. INtRODUCtION concrete LCAs [6, 7] .
The production of cement-based products is responsible for a
significant portion of global CO 2 emissions. In particular, 6-7% Many studies use physical characteristics of concrete such as
3
[1]
of global CO 2 emissions can be attributed to the production volume or mass (ex. 1 m or 1 kg) as the functional unit [8, 9] .
of cement, which requires 3 GJ of energy per ton of clinker This neglects important functional requirements for concrete,
[2] and is the component of concrete that has the highest such as strength and durability. There is substantial literature
environmental impact. For the past several decades, one on the development of metrics that evaluate environmental
strong motivation for the development and implementation performance and a correspondingly large number of
of alternative options to conventional concrete mix designs indices have been proposed. Rametsteiner et al. [10] argues
has been motivated by the need to reduce both cost and that the role of sustainability indicators “is to structure and
negative environmental impacts. Research efforts have resulted communicate information about key issues and their trends
in the proliferation of concrete mix designs in industry that are considered relevant for sustainable development”; the authors
claimed to be ‘greener’ or more sustainable than traditional acknowledge that the development of sustainability indicators
concrete mix designs. extends beyond technical calculations and must include political
or philosophical value judgements about how sustainability
Life Cycle Assessment (LCA), which is defined as “the is defined and measured. In light of this complexity, Moldan
compilation and evaluation of the inputs, outputs and potential et al. [11] argue that it is not the calculation of indicators that
environmental impacts of a product system throughout its life is the challenge, but rather, the selection of appropriate

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