Life cycle assessment for roads constructions and use

Posted by crespibozzoluis
Contact: 
EUPAVE European Concrete Paving Association Vorstlaan 68 boulevard du Souverain 1170 Brussels T +32 2 790 42 06 F +32 2 640 06 70 info@eupave.eu www.eupave.eu
Type: 
article
Comparative: 
yes
Publication year: 
2011
Language: 
English
Code: 
Construction/Building
Product: 
Motorways
Quality and sources
Is the study a: 
Detailed LCA
Was a critical review performed?: 
Yes
Is the study compliant with ISO 14044?: 
Yes
Sponsor name(s): 
Centre for Building Materials, Technische Universität München, Germany.
Sponsor type: 
University
Practitioner(s): 
Charlotte Milachowski
Practitioner(s): 
Thorsten Stengel
Practitioner(s): 
Christoph Gehlen
Practitioner(s) type: 
Institut/Technical research center
Summary
Functional unit: 
1 km long section of two-lane motorway section
Goal and scope of the summary: 
The goal of this LCA is to quantify the environmental impact of motorways, as well as pavement construction, the ecological impact of a motorway under traffic and the effect of maintenance over a period of 30 years. The scope: The impact of the construction and use of four different pavement types were studied: two concrete pavements and two asphalt pavements. Scenarios investigated: construction, use and maintenance for 30 years of service, reduction potential of environment impact. Limits: Life cycle assessment takes only ecological aspects into account, not the social and economical factors which must be considered for decision-making in civil engineering. LCA only covers standard cases, whereas the choice of a suitable and ecological construction method often depends strongly on local circumstances. In some circumstances, the potential environmental impact could even be less than in the standard case.

Construction:
For concrete pavements motorways, the potential environment impact depends on the cement type. By replacing CEM I by CEM III, GWP is reduced by amounts of 20-21%.
The largest effect is due to the Portland cement and lies between 70 (EP) and 96% (GWP).
Other contributions originate mainly in requirements on infrastructure and transport processes.
Depending on the category, the frost blanket contributes between 14 (GWP) and 38% (EP) to the environmental impact and the use of 100% recycled material in the this layer reduces the impact by amounts between 12 (GWP) and 31% (EP), depending on the category.

For all categories of asphalt pavements the largest proportion of the potential environmental impact originates in the asphalt itself, as in the case of concrete pavements.
The contribution of the frost blanket ranges from 11 to 31%, depending on the category, and is largest for the eutrophication potential. Using 100% recycled material in the frost blanket lowers the environmental impact in all categories, by 10 (ODP) to 26% (EP).

Comparing asphalt and concrete pavements construction, apart from the GWP, the potential environmental impact with concrete was found to be lower than with asphalt. The largest contribution to GDP of the concrete construction method (166% higher than asphalt) is delivered by the Portland cement. Their effect on POCP and EP is similar. For ODP the asphalt construction methods cause a potential environment impact which is 300% more than with concrete. In the case of AP, the impact is 135% more with asphalt

The potential environment impact can be decreasing by reducing transport activities. The ODP is very much affected by the actual transport processes involved.

Usage and maintenance:
All the impact categories for the maintenance measures show much less environmental impact for the concrete pavements than the asphalt pavements. For ODP the asphalt pavements causes a potential environmental impact which is 430% more than with concrete. In the case of POCP, AP and EP the impact is from 160% to 220% more with asphalt.

A durable construction methods and roads with low maintenance requirements offer significant advantages

Traffic contributes a major proportion of the total emission of air pollutants. The potential environmental impact due to traffic load is 100 times more than due to construction and maintenance together.

The properties of pavements as texture, flatness and stiffness, have a significant influence in the reduction of air pollution and fuel consumption.
So construction methods aimed at lowering fuel consumption are far more environmentally effective than construction methods tailored to low impact during construction and use.

Material impact(s): 
Ozone layer depletion
Raw material impact level: 
Low
Manufacturing impact(s): 
Global warming
Manufacturing impact level: 
Low
Shipping impact(s): 
Ozone layer depletion
Shipping impact level: 
Low
Usage impact(s): 
Global warming
Usage impact level: 
High

In my opinion, this is a very

In my opinion, this is a very interesting look into the effects of pavements texture and how we can significantly reduce air pollution as well as consumption of fuel. Will definitely use some of these practices in future assessments. Thank you and acrobatic regards, Giles Lambert.




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