Page 264 - New Trends in Eco efficient and Recycled Concrete

232 New Trends in Eco-efficient and Recycled Concrete

and the recycled material. In general, these LCA studies are performed under the
zero burden principle, which is the notion that waste does not hold any past
energetic-environmental burdens when entering a recycling process.
Generally, consequential LCA approaches are generally advantageous for
recycled materials due to the application of environmental credits. However,
Marinkovi´ c et al. (2017) show concern about the complete attribution of the envi-
ronmental gain to the product that receives the waste, when it could be also shared
with the activity which generates the waste. Chen et al. (2010b) also argued against
the system expansion due to its problems to ensure a global coherency between var-
ious LCA studies. However, in the assessment of the environmental burden of con-
struction materials, it has been found that either choice of modelling results in
comparable results (Santos Vieira and Horvath, 2008). The unit of study there was
the concrete used in a building frame. Obviously, the considered system boundaries
for the attributional and consequential LCA approach were highly different (see
Fig. 9.4).
Moreover, the ILCD handbook recommends the use of consequential modelling
for comparisons amongst products, that is, decision supporting, (Ekvall et al., 2016)
since this approach seeks to identify the consequences of changes.

Figure 9.4 System boundaries used by Santos Vieira and Horvath (2008) for attributional
LCA (dashed line boundary) and consequential LCA (full line boundary) of concrete (with
incorporation of recycled aggregates) used in a building frame (Note: dash-dot lines
represent markets). LCA, life cycle assessment.