1982
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
includes different types of plastics. Country-specific
electricity mixes are modelled for each company and thus
impacts of electricity consumption depend not only on the
amount of electricity needed but also on its mix. The higher
share of electricity in CED renewable can be explained by the
use of hydroelectric power plants in the electricity mixes of
several factories. And the relatively high share in
eutrophication is mainly due to electricity from lignite.
The share of heating energy and fuel consumption for
forklifts is between 0.01 % (land competition) and 2.8 %
(global warming) and is thus not considered to be of primary
importance. With regard to land competition the geosynthetic
production plays an important role. The impacts are
dominated by the direct land use, i.e. land which is occupied
by the manufacturer plant in which the geosynthetic is
produced. Indirect land uses, i.e. land occupation stemming
from upstream processes, are significantly lower because no
land occupation is reported in the inventories of plastic
feedstock and no land intensive products such as wood are
used in considerable amounts. Water consumption is included
in the working materials. As a consequence, this category
bears about 5 % of the total amount of water used.
Figure 3. Environmental impacts of the life cycle of 1 kg geogrid. Geosynthetic includes direct burdens of the geosynthetic production. Raw materials
include plastic, extrusion if necessary and additives, working materials include water (tap and deionised) and lubricating oil, other energy includes
thermal energy and fuels, infrastructure covers the production plant and disposal comprises wastewater treatment and disposal of different types of
waste.
5 DISCUSSION AND CONCLUSION
The use of geosynthetics leads to lower environmental impacts
of slope retention in all indicators investigated. The specific
climate change impact of the construction of the slope retention
(1 m slope retention with a 3 meters high wall) using
geosynthetics is about 1 ton CO
2
-eq per meter lower compared
to a conventional alternative. This difference is equal to about
84 % of the overall climate change impact of the construction
and disposal efforts of an entire conventional slope retention
system during its 100 years lifetime.
If a Euro5 lorry with lower exhaust emissions than an average
fleet lorry is used for the transportation of materials, the
environmental impacts of both cases are somewhat reduced
regarding some indicators. However, this does not affect the
overall conclusions of the comparison.
Slope retentions are individual solutions in a particular
situation. The height of slope retention walls and the horizontal
loads on it may differ, which may lead to differences in
thickness and reinforcement. Thus, generalising assumptions
were necessary to model a typical slope retention. Data about
on-site material used, gravel extraction, concrete and the use of
building machines are based on generic data and knowledge of
individual civil engineering experts.
Based on the uncertainty assessment it can be safely stated that
the geosynthetics reinforced slope retention shows lower
environmental impacts than the concrete wall. Despite the
necessary simplifications and assumptions, the results of the
comparison are considered to be significant and reliable.
A geosynthetic reinforced wall used for slope retention
constitutes a different system compared to a concrete reinforced
wall. Nevertheless, both systems provide the same function by
enabling the build-up of steep walls. Compared to the
conventional slope retention, the geosynthetic reinforced wall
substitutes the use of concrete and reinforcing steel, which
results between 63 % and 87 % lower environmental impacts.
6 REFERENCES
ecoinvent Centre (2010) ecoinvent data v2.2, ecoinvent reports No. 1-
25. Swiss Centre for Life Cycle Inventories, Duebendorf,
Switzerland, retrieved from:
.
Frischknecht R., Jungbluth N., Althaus H.-J., Bauer C., Doka G., Dones
R., Hellweg S., Hischier R., Humbert S., Margni M. and Nemecek
T. (2007) Implementation of Life Cycle Impact Assessment
Methods. ecoinvent report No. 3, v2.0. Swiss Centre for Life Cycle
Inventories, Dübendorf, CH, retrieved from:
.
Goedkoop M., Heijungs R., Huijbregts M. A. J., De Schryver A., Struijs
J. and van Zelm R. (2009) ReCiPe 2008 - A life cycle impact
assessment method which comprises harmonised category
indicators at the midpoin and the endpoint level. First edition.
Report I: Characterisation, NL, retrieved from: lcia-recipe.net/.
Guinée J. B., (final editor), Gorrée M., Heijungs R., Huppes G., Kleijn
R., de Koning A., van Oers L., Wegener Sleeswijk A., Suh S., Udo
de Haes H. A., de Bruijn H., van Duin R., Huijbregts M. A. J.,
Lindeijer E., Roorda A. A. H. and Weidema B. P. (2001a) Life
cycle assessment; An operational guide to the ISO standards; Part
3: Scientific Background. Ministry of Housing, Spatial Planning
and Environment (VROM) and Centre of Environmental Science
(CML), Den Haag and Leiden, The Netherlands, retrieved from:
.
Guinée J. B., (final editor), Gorrée M., Heijungs R., Huppes G., Kleijn
R., de Koning A., van Oers L., Wegener Sleeswijk A., Suh S., Udo
de Haes H. A., de Bruijn H., van Duin R., Huijbregts M. A. J.,
Lindeijer E., Roorda A. A. H. and Weidema B. P. (2001b) Life
cycle assessment; An operational guide to the ISO standards; Parts
1 and 2. Ministry of Housing, Spatial Planning and Environment
(VROM) and Centre of Environmental Science (CML), Den Haag
and
Leiden,
The
Netherlands,
retrieved
from:
.
PRé Consultants (2012) SimaPro 7.3.3, Amersfoort, NL, retrieved from:
.
Solomon S., Qin D., Manning M., Alley R. B., Berntsen T., Bindoff N.
L., Chen Z., Chidthaisong A., Gregory J. M., Hegerl G. C.,
Heimann M., Hewitson B., Hoskins B. J., Joos F., Jouzel J., Kattsov
V., Lohmann U., Matsuno T., Molina M., Nicholls N., Overpeck J.,
Raga G., Ramaswamy V., Ren J., Rusticucci M., Somerville R.,
Stocker T. F., Whetton P., Wood R. A. and Wratt D. (2007)
Technical Summary. In: Climate Change 2007: The Physical
Science Basis. Contribution of Working Group I to the Fourth
Assessment Report of the Intergovernmental Panel on Climate
Change (IPCC), Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA.
Stucki M., Büsser S., Itten R., Frischknecht R. and Wallbaum H. (2011)
Comparative Life Cycle Assessment of Geosynthetics versus
Conventional
Construction
Material.
ESU-services
Ltd.
commissioned by European Association for Geosynthetic
Manufacturers (EAGM), Uster and Zürich, CH.
