International Symposium LCA & Construction LCA case studies and methods for infrastructures
Life cycle assessment of orthotropic steel bridge decks covered by bituminous concrete or UHPFRC topping layer Fernanda Gomes1, M. Rivallain1, A. Feraille1, P. Marchand2, C. Tessier3 & F. Toutlemonde2
1 Univ. Paris-Est, Navier Laboratory, Ecole des Ponts ParisTech (France) 2 Univ. Paris-Est, IFSTTAR, Paris (France) 3 Univ LUNAM, IFSTTAR, SOA (France)
Context presentation
R&D projet
PhD thesis objective
Evaluation of the influence of the topping layer on fatigue behavior of orthotropic steel bridge decks
Traditional solution: bituminous concrete
Innovative solution: UHPFRC
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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PhD main results
Déformation sous chargt Plaque A - 45 kN
UHPFRC overlay
600 500 400
déformation (μm/m)
300 200 100 0 1000
1050
1100
1150
1200
1250
-100
1300
1350
1400
T14 nue sans trou T14 nue avec trou T14 + BB T10 + BFUP treill - début T10 + BFUP treill - fin T12 + BFUP gouj - début T12 + BFUP gouj - fin
-200 -300 -400
distance sur axe transversal AA' (mm)
Bituminous concrete overlay
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Goal & scope
LCA study objective
Compare two alternative designs of orthotropic deck covered with different types of pavement overlay: bituminous concrete (BC) and UHPFRC
Traditional solution
Innovative solution
70 mm of bituminous concrete
4 mm of epoxy resin
steel plate of 13mm
steel plate of 10mm
35 mm of UHPFRC
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Goal & scope
System
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Goal & scope
System
MILLAU VIADUCT: a multi cable-stayed bridge, 32,05 m wide, with an orthotropic steel deck
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Goal & scope
Functional unit
Allowing the crossing of a distance of 2460 m to a traffic load of 3,000 vehicles/hour (heavy and light) and submitted to wind loads of Millau region, over a service life superior to120 years
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Life cycle inventory analysis
Materials production phases
Some insights on materials quantities for the steel frames Differentiated design according to the dead loads
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Life cycle inventory analysis
Construction phase
Earthworks
Concrete pumping
Bottom side painting of the steel frame
Bridge deck set up by successive translations
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Life cycle inventory analysis
Maintenance phase (service lifetime)
Bituminous concrete
15 years and then periodically every 30 years The coating layer is scraped by 20 mm, then a new bituminous concrete topping layer 25 mm thick is implemented;
30 years and then periodically every 30 years The entire coating layer is removed (75 mm), then a new BC topping layer of 70 mm is implemented; anti corrosive layer and sealing layer, are both replaced.
UHPFRC
End
Only the 4 mm of epoxy resin are renewed, periodically every 30 years.
of life… International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Distribution of environmental impacts on the whole life cycle of orthotropic steel deck viaduct covered by the bituminous concrete
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Distribution of environmental impacts on the whole life cycle of orthotropic steel deck viaduct covered by the UHPFRC
The share of the environmental impacts related to the different life cycle (LC) phases is very similar.
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Distribution of environmental impacts on the whole life cycle of orthotropic steel deck viaduct covered by the UHPFRC
Materials production phase represents over 65% of the impacts generated on the LC
Steel deck production: 18% to 35%, depending on the analyzed indicator Reinforcing steel production: about 20% International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Distribution of environmental impacts on the whole life cycle of orthotropic steel deck viaduct covered by the UHPFRC
The impacts due to the construction phase are supposed to be negligible in this study. However, this conclusion should be tempered considering the simple modeling assumptions. International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Distribution of environmental impacts on the whole life cycle of orthotropic steel deck viaduct covered by the UHPFRC
The environmental impacts generated by the materials transport phase and the end of life phase are low compared to the overall assessment, except for the photochemical oxidation indicator for which the materials transport phase is responsible for almost 20% of the whole impact. International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Distribution of environmental impacts on the whole life cycle of orthotropic steel deck viaduct covered by the UHPFRC
Maintenance impacts are largely attributable to the overlay system: 4% to 24% of environmental life cycle impacts, depending on the indicators and the design type.
International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Environmental assessments of the two viaduct designs
None of these two designs dominates the other; none of them demonstrates better performances on all environmental indicators considered, over the viaduct life cycle. Further analysis through normalization could be conducted to help decision
making. International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Influence of epoxy resin coating layer on the environmental performance of the viaduct
UHPFRC without the epoxy presents a better environmental performance than the structure with BC for all indicators.
The identification of a different wearing course with mitigated impacts would be a promising target for further research. International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Influence of UHPFRC maintenance on the environmental performance of the viaduct
An additional scenario for the UHPFRC maintenance has been considered: every 50y, the UHPFRC coating layer and the welded steel meshes are changed.
Under this assumption, the environmental impacts of the viaduct involving orthotropic steel deck topped with UHPFRC increase by 7% to 14% (except for the cumulative energy demand impact). International Symposium LCA & Construction – LCA case studies and methods for infrastructures
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Conclusions
The simplified modeling study highlights some important points for a future eco-design of this kind structures: revue the application of epoxy resin.
The maintenance phase is responsible for large environmental impacts. It is important to consolidate the durability hypotheses of the UHPFRC topping layer.
The operational difficulties related to the identification of relevant environmental data reinforce the need for a specific cycle life inventory database, adapted to civil engineering materials and processes
development of DIOGEN group : www.diogen.fr
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