Page 240 - New Trends in Eco efficient and Recycled Concrete

208 New Trends in Eco-efficient and Recycled Concrete

numerous methods for the evaluation of the environmental impacts, a life cycle
assessment (LCA) is one of the most widely employed techniques due to its profi-
ciency to calculate the potential effects that a product, process or service has on the
environment over the entire period of its life cycle. This chapter focuses on the
particularities of the ecological profile of concrete with recycled aggregates from
CDW as assessed using LCA.

9.2 Ecological background of the concrete sector

Estimates indicate that among construction materials concrete is the most employed
material worldwide with around 1 t per inhabitant and year (Van den Heede and De
Belie, 2012). For instance, in 2015, the total production of concrete, both ready-mix
and precast, was estimated as 344.3 million cubic metres in Europe (ERMCO,
2016). Up to 45% of the aggregates employed in Europe are used in concrete
(UEPG, 2017) and since these materials represent 80% by mass of the total weight
of a concrete structure, concrete production consumes around 1.2 billion tonnes of
aggregates in Europe. Both facts make concrete the perfect receptor of large quanti-
ties of residual products as recycled aggregates which concurrently solves the waste
generation problem and reduces the consumption of natural resources (Damtoft
et al., 2008). Unquestionably, this measure incorporates a sustainability aspect to
the production of recycled concrete, which could be considered as an eco-efficient
material since the final product satisfies the human necessities at a competitive
price while reducing the environmental impacts resulting from its production
(Keffer et al., 1999).

9.2.1 Environmental impacts
9.2.1.1 Cement

Environmental impacts of cement manufacturing can be global, regional or local in
scale (Huntzinger and Eatmon, 2009):
Global scale: Over the past few decades, the emphasis has clearly shifted
towards a global focus on climate change. Table 9.1 presents a summary of values
found in literature for cement-related CO 2 emissions (Humphreys and Mahasenan,
2002; Damtoft et al., 2008; Hendriks et al., 2011; Josa et al., 2004; Febelcem,
2006; Malhotra, 2004; Price et al, 1999; Flower and Sanjayan, 2007; ATILH, 2002;
Gartner, 2004). These are usually the sum of the CO 2 emitted during the calcination
process [raw material CO 2 : RM-CO 2 (Gartner, 2004)] and the CO 2 associated with
energy use. With respect to the latter, a distinction can be made between indirect
and direct energy bound CO 2 (IEB- and DEB-CO 2 ). IEB emissions comprise the
CO 2 emissions associated with the generation of electrical power to operate the
cement plant, while the direct energy bound emissions are associated with the fuel
combustion in the cement kiln.