Civil Engineering Reference
In-Depth Information
∑ large consumption of natural resources;
∑ large consumption of energy (mostly for cement production and
reinforcement steel production; in addition, for operation and maintenance
of buildings and other structures; finally for transportation, construction,
demolition and recycling to a lesser extent);
∑ large emissions of greenhouse gasses, primarily Co
2
which are responsible
for climate change and originate mostly from cement production and
energy consumption; to a lesser extent, emissions of So
2
which is
responsible for acidification and mostly originates from the transportation
phase;
∑ large amount of construction and demolition waste produced.
Therefore, concrete has a large impact on the environment because of
its enormous production and utilization. That is why the environmental
assessment of concrete is of great importance with regard to the efforts
towards creating a sustainable society. There are many methodologies for
evaluating the environmental loads of processes and products during their
life cycle, but the most widely acknowledged (and standardized) is life cycle
assessment (LCa).
3.2 General description of life cycle assessment
(LCA) methodology
LCa is a methodology for evaluating the environmental loads of processes
and products during their life cycle. according to iSo standards 14040-14043
(iSo, 2006a), LCa consists of four steps: (1) goal and scope definition,
(2) creating the life cycle inventory (LCi), (3) assessing the environmental
impact (LCia) and (4) interpreting the results (Fig. 3.1).
The first step of an LCa involves the goal and scope definition. The goal
of an LCa study must be clearly defined including the intended application,
the intended use of the results and users of the results (intended audience).
The goals of an LCa study are, for example, to compare two or more different
products fulfilling the same function, to identify improvement possibilities in
further development of existing products or in innovation and design of new
products, etc. The definition of the scope of an LCa study sets the borders of
the assessment: what is included in the modeled system and what assessment
methods are to be used. The following items must be clearly described within
the scope definition: the system to be studied and its function, the functional
unit, the system boundaries, the types of impact and the methodology of
impact assessment, data quality requirements, assumptions and limitations,
the type of critical review, if any (Jensen et al., 1997). Detailed information
on each of these items is given in Section 3.3.
inventory analysis is the second step in an LCa. it involves data collection
