Environ. Sci. Technol. 2009, 43, 2066–2071
Simplified Environmental Study on Innovative Bridge Structure LINA BOUHAYA,* ROBERT LE ROY, AND ´ L A ¨I D E F E R A I L L E - F R E S N E T ADE UR Navier, Université Paris-Est, Ecole des Ponts Paris Tech, 6 & 8 av Blaise Pascal, Champs-sur-Marne, 77455 Marne la Vallée Cedex 2, France
Received May 16, 2008. Revised manuscript received October 21, 2008. Accepted December 19, 2008.
The aim of this paper is to present a simplified life cycle assessment on an innovative bridge structure, made of wood and ultra high performance concrete, which combines mechanical performance with minimum environmental impact. The environmental analysis was conducted from cradle to grave using the Life Cycle Assessment method. It was restricted to energy release and greenhouse gas emissions. Assumptions are detailed for each step of the analysis. For the wood endof-life, three scenarios were proposed: dumping, burning, and recycling. Results show that the most energy needed is in the production phase, which represents 73.4% of the total amount. Analysis shows that the renewable energy is about 70% of the production energy. Wood, through its biomass CO2, contributes positively to the environmental impact. It was concluded that no scenario can be the winner on both impacts. Indeed, the end-of-life wood recycling gives the best impact on CO2 release, whereas burning wood, despite its remarkable energy impact, is the worst. According to the emphasis given to each impact, designers will be able to choose one or the other.
1. Introduction Nowadays, industry is more interested in reducing the environmental impact of its products as a consequence of global warming. Much research has been done in the residential sector comparing the environmental impact of various civil engineering structures. The aim of this project is to bring elements that allow the owner and the constructor to make decisions regarding the new transportation infrastructure and the selection of materials. It is reasonable to assume that structural innovation may be developed in the future only after being environmentally assessed. Thus, in this paper, we studied a new structure that has also shown its structural potential (1, 2). The study relates to 25 m span bridge structures. The work studied supports a 10 m roadway with two lanes. The structure is suitable to mean span, given that bridges with span varying between 10 and 25 m represent about 80% of the transportation infrastructure in Europe (3). This structure is inspired by that presented by Tanis et al. (2) for a 10 m span. The structure includes a 7 cm thickness UHPC slab fastened on 14 wood beams of 1.2 m in height, 24 cm in width, separated by 51 cm of clear space. * Corresponding author phone: (33) 1 64 15 37 34; fax: (33) 1 64 15 37 41; e-mail:
[email protected]. 2066
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A life cycle assessment (LCA) of this type of bridge structure is carried out in order to evaluate the total environmental impact produced during the entire bridge life cycle, considering, according to ref 4, a typical service life duration (TLD) of the bridge of 100 years. In the whole analysis, we do not take into consideration the foundations and the fitting out of the structure, i.e., barriers, sidewalk, pavement, waterproofing material and so on. The functional unit considered is a 25 m span bridge deck supporting roads or motorways with medium flow rates of lorries, which corresponds to traffic category number 2, according to ref 5. We decided to limit our analysis to the total energy and the greenhouse gas emissions, the latter being indicated by the carbon dioxide equivalent. In the first part of this article, we present data related to the materials used. The assumptions made and the limits of our study are also presented. In the final part, we present the results of our study related to the CO2 release and energy use throughout the whole life cycle of the structure. Different assumptions related to wood end-of-life and their consequences on the LCA are also presented.
2. LCA and Materials Data 2.1. Production Phase. The ISO standards 14040 (20) and ISO 14044 define LCA methodology which is used in the research and development (R&D) sector. On the other hand, the ISO 14025 standard defines environmental product declaration (EPD), and gives more precise rules for different types of product. In France, a standard (NF P01 010 (21)) was put in place in December 2004; it defines methodological rules and indicators for EPDs in the building sector. EPDs deal with a unit function that is a structural element with specified dimensions. In our project, we used the EPDs of the glulam girder (6), that of the concrete wall (7) and the LCI of engineering steel. LCI, life cycle inventory, is a phase of LCA including the compilation and the quantification of inputs and outputs for a given system of products in its entire life cycle. According to the French EPD of the glulam girder (6), the unit function of wood is taken as a part of a beam of 0.28 m3 in volume. Assuming that the data remain proportional to the volume, which is reasonable because the same industrial techniques are required, we extrapolated the production energy for a cubic meter of wood. Extrapolating the data in the wood EPD for a unit function to one cubic meter, we obtain a quantity of -0.48 t of CO2 released/m3 of wood and a total energy (T.E.) of 19 000 MJ/ m3 of wood. The total energy is composed of renewable energy and nonrenewable energy. The French EPD of the glulam girder considers that 62% of the renewable energy is due to photosynthesis, 34% comes from wood byproduct used for heating energy in sawmills, and 4% is the renewable part of electricity production (hydroelectricity and so on). Hence, the non renewable energy (N.R.E.) is only about 5500 MJ/m3 of wood. UHPC is a high performance material, with a compressive strength of 150 MPa, which is 5 times greater than that of building concrete. This material contains engineering steel fibers, silica fume that is a byproduct of the silicon industry, cement, fine aggregates, a water reducing agent, and water. It requires 1000 kg cement/m3, whereas building concrete requires only 350 kg cement/m3. There are no environmental data available on this new material, so we have done the calculation on the basis of the summation of the contribution of the components as shown below. 10.1021/es801351g CCC: $40.75
2009 American Chemical Society
Published on Web 02/04/2009
TABLE 1. UHPC Constituent Contribution (per m3 of UHPC) constituent
kg/m3 BFUP
fabrication energy (MJ/m3)
transportation energy (MJ/m3)a
CO2 release due to fabrication (kg/m3)
CO2 release due to transportation (kg/m3)
cement water silica fume aggregates fibers water reducing agent
1000 200 250 750 195 40
4920 0 0 18.846 2578 3.5
350 0 87.5 210 68.25 0
865 0 0 0.982 183.3 0.736
28 0 7 16.8 5.46 0
a
From the source to the mixing plant.
TABLE 2. Gathered Data for Energy and CO2 Release for UHPC Constituents and Mixing material engineering steel cement CEM I aggregates water reducing agent (w.r.a) silica fume mixing
energy
CO2 release 3
103 GJ/m 4.92 GJ/t 25.128 MJ/t 447 MJ/t 87.5 MJ/m3 15 MJ/m3
7.3 t. CO2/m3 865 kg CO2/t 0.982 kg CO2/t 92 kg CO2/t 7 kg/m3 0.070 kg/m3
We consider a distance of 400 km between the aggregates quarry and the mixing plant, and 500 km between the cement works and the mixing plant. For fibers and silica fume, the transportation is also estimated at 500 km. Water is supposed to be available in the factory. Because the water reducing agent is used in small amounts (8 kg dry/m3 UHPC), we will see later that we can neglect its effect (Table 1). Assumptions about distances were set according to the specificity of the materials. The UHPC for example, is prepared with high resistance fine quartz sand, which is available in few areas in Europe. Similarly, only a few French cement factories reach resistance required for such materials. A cubic meter of UHPC is considered to be made up of 1000 kg of cement, 200 kg of water, 250 kg of silica fume, 750 kg of aggregates, and 195 kg of fibers. For the mixing stage, an energy of 15 MJ/m3 and a CO2 emission of 70 g/t (or 10 times greater than the C 40/45) are considered (internal data from LCPC Nantes). Hence the total quantity of CO2 released due to manufacture is about 1107 kg CO2/m3 of UHPC and the total manufacture energy is about 8229 MJ/m3 of UHPC. Detailed calculation is shown in Table 1. Data for aggregates, cement, engineering steel, and water reducing agent related to the production of these materials are shown in Table 2. Engineering steel data come from International Iron and Steel Institute IISI as LCI data (19). They consider that 40% of steel is recycled. Data of aggregates come from an internal study and those for water reducing agent from 2005 SIKA data. Because silica fume is a byproduct of the silicon industry, we consider that its impact is due to only its transport to the UHPC mixing plant. As for cement, Gartner (8) considers average values for the CO2 release and the energy of all cement categories production for North America. He gives an energy of 4.2 GJ/t clinker and a CO2 release of 815 kg CO2/t clinker. The values given in the table below come from the French cement industry; they are close to that of Gartner but slightly higher because we are dealing with pure Portland cement CEM I. Data for glue, used to join the concrete slab to glulam beams, are taken from the SIKA industry. Energy consumption is 45.5 GJ/m3 of glue and CO2 release is 10600 kg CO2/m3 of glue. 2.2. Transportation Phase. This phase takes into consideration the transportation of wood beams and UHPC slabs from the factory to the site. The transportation energy is a function of the distance that differs from one material to
another depending on the availability of these materials and transportation means. For instance, wood and steel are generally transported over long distances. On the other hand, ordinary concrete is usually mixed close to the job site. The transportation distances of UHPC materials are nevertheless logically much greater than those of ordinary concrete, as was observed for the construction of recent French UHPC bridges (enlargement of Rouen’s Bridge for instance). The energy of the transportation phase is calculated on the basis of the French Standard FD P 01-015 (9) based on the series ISO 14040-14044. It reproduces LCI data energy in France and Europe as well as the transportation energy and specifies the rules for use of the data. The transportation energy varies greatly from one mode of transportation to another. It is close to 0.11 kJ/km kg by boat, 0.7 kJ/km kg by truck, and 0.1 kJ/km kg by railroad. For road transportation, the consumption of fuel for the transportation of a product can be estimated by the formula given below. It gives the amount of diesel fuel needed to carry a 24 ton load in a truck, consuming 38 L of diesel per 100 km. This consumption is about 2/3 × 38 L for an empty truck. According to FD P 01-015 code (9), it is considered that 30% of the trucks return empty to their starting point. Thus, the amount of diesel fuel consumed to transport a quantity Q of a product is Q 2 38 1 Cr 2 d + + 0.3 N; N ) 100 3 24 3 3 Cr
(
)
where Q, d, and Cr are, respectively, the total quantity of a product (tons), the transportation distance (km), and the actual load transported by the truck, including the weight of packaging and pallets (tons). Therefore, the energy is calculated by taking a diesel net calorific value (NCV) of 42000 MJ/t. On the other hand, we assume that the release of CO2 from a truck is proportional to its consumption; the ratio is taken as 2.7 kg CO2/L for standard fuel (10). We consider a transportation distance of 300 km for the UHPC and for the wood, taken according to the factory distribution on French soil. 2.3. Construction Phase. The particularity and the advantage of this structure is that it is light enough to be put in place at once with a high-capacity crane. It is one of the innovative aspects of the solution proposed. Usually, bridges are built in situ on tower scaffolding, which takes several months. It is therefore expected that the impact of the construction phase is low in the global assessment for the solution proposed. The assembly of the bridge is done in a 360 m2 (with respect to bridge dimensions) temporary workshop near the job site. Indeed, a tunnel heated greenhouse is suitable for this kind of job thanks to its lightness and ease of assembly. Gluing operations of UHPC slab on wood beams are carried out at 20 degrees; for this, an electric generator, supplied by a generating set, is used. According to the French Environment and Energy Management Agency (ADEME) data (11), VOL. 43, NO. 6, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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we considered the average value for energy loss of 300 kWh/ m2.year which leads to a total energy of 5.3 GJ for 5 days assembly. Data for the lift up operation were given by the mobile crane constructor Liebherr (12). The bridge weight being close to 100 t, a 500 kW power crane (LTM 1500-8.1 model) is necessary to put the bridge deck in place. This model is brought on site in five separate pieces, each one in a truck. It is not widespread in France; hence, we consider a transportation distance of about 400 km, which leads to a total consumption of 912 L of gas oil. Energy and CO2 release are calculated according to the method detailed in paragraph 2.2. The energy amount of crane transportation is then 45 GJ. The bridge deck is erected in one day (6 h). The energy necessary for the erection is about 10.8 GJ. In total, the construction phase requires 61.1 GJ in energy. The mean performance for both the crane and the generator is about 42%, the NCV of diesel is 42000 MJ/t, and the specific gravity is 0.845. Hence, the CO2 release is 0.96 t for the generator, 1.95 t for the deck erection, and 2.46 t for crane transportation. In total, the construction phase releases 5.37 t of CO2. 2.4. Maintenance Phase. Because we are dealing with an innovative structure, there were no data available on its maintenance. The only solution seems to calculate the impact through the quantity of material replaced during the life cycle. This amount does not exist in the literature. Nevertheless, we considered separately the 2 main materials from which the deck is made, assuming that deck elements could be individually replaced. First, as UHPC is an ultra durable material, we assume that it does not need maintenance for 100 years, the expected life span of a bridge. To justify this hypothesis, it is noteworthy that UHPC has a porosity of less than 2% and an air permeability of less than 1 × 10-20 m2 (13), which are much lower than those given by Baroghel-Bouny for very high durable concrete (14). In fact, Baroghel-Bouny gives five classes for “potential” concrete durability rated from very low to very high. Her hypotheses were approved by the French Civil Engineering Association AFGC. The very high class corresponds to concrete having water porosity between 6 and 9% and gas permeability less than 30 × 10-18 m2, Of course, the lower these numbers, the better the durability. Moreover, Resplendino (15) supports this hypothesis while considering the UHPC bridge as a light structure that does not need maintenance or repair. Second, dealing with wood, we estimated the number of beams that should be replaced during the TLD. To this end, we based our calculation on the Gerold study (16), which presents an economic balance of wood bridge maintenance. Gerold concludes that the maintenance of a wood bridge costs 0.6%/year from the initial cost of the bridge. Although we are aware of our unrefined estimate, we assume that the relative volume of a material is proportional to its relative cost, and that this cost is estimated as 50% of the total cost; the other 50% is due to labor and machines. Hence, the maintenance phase consists of replacing, during TLD, 30% of wood beams, with necessary glue. Numbers include wood beam and glue production, transportation and putting in place. The latter is considered as negligible. We considered in this phase rough hypotheses that may be changed in the future with more accurate data. However, we will see that the LCA result is not very sensitive to these assumptions. 2.5. Demolition and End-of-Life Treatment. The endof-life phase includes the demolition of the structure and the material’s treatment. The demolition consists of taking apart the bridge and separating the UHPC slab from the wood beams. The end-of-life treatment of these two materials is done apart as shown below. 2068
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We consider the assumptions for the demolition phase to be the same as for the construction. It is done in one day with the same crane so the energy used is about 55.8 GJ and the CO2 release about 4.41 t of CO2. The end-of-life treatment of materials is an important question which will certainly increase in the future. On the other hand, wood appears to be an interesting material that can be treated at least in three different ways. It can be burned, recycled or constitute a carbon sink. Therefore, we consider three scenarios for the wood end-of-life treatment. The first one (scenario 1), based on the wood EPD (6), consists in burying wood beams in landfill. This last document considers that only 15% of dumped wood deteriorates and releases carbon dioxide and methane, the remaining 85% constitutes a stock of carbon. This hypothesis is validated by Eleazer, who obtained, in laboratory tests, results of the same order (17). Because these results do not depend on the functional unit but on the type of material, these percentages have been applied in our study. Nevertheless, this scenario, presently adopted in France, may change in the future. Indeed, it is likely that wooden bridges built today will be the subject of recycling in a hundred years at the end of their life. For this reason, the second scenario (scenario 2) consists in the valorization of wood in energy heating. We calculated the fossil energy saved by wood burning, compared to natural gas burning. The inferior calorific value of wood is about 7452 MJ/m3, according to (18) (data from the Ministry of Industry for wood byproduct having a humidity of 10%). Assuming that wood and gas boilers have the same mean performance, we can deduce this last amount to the global energy flow. This scenario was also applied on the maintenance step by burning the replaced beams. We can note that 1 MJ of burned natural gas releases 61 g of CO2. On the other hand, 1 MJ of burned wood releases 100 g of CO2. Hence, while burning wood, we save energy but produce more CO2, equal to 39 g, the excess of CO2 released by wood compared to natural gas. Finally, the third solution (scenario 3) is to reuse the wood in an industrial recycling chain. The mass elements may be recovered in the realization of particle board type, such as oriented strand board for example, or wood fiber insulation board. In this case, the end-of-life balance is taken as zero. Data for the three scenarios were provided by the Environmental department of the French Wood Technical center (FCBA, Paris). The results are given in Table 3. Concerning the concrete end-of-life, we followed the conclusions mentioned in ready mixed concrete EPD (7), in which it is stated that 40% of the demolished concrete is recycled. Nethertheless, it is likely that reuse of dumped UHPC is used for lower strength concrete and then would not be profitable for UHPC. This aspect has not been taken into account here. Having the same components as the ready mixed concrete, UHPC is assumed to have been dumped in the same way; hence we considered the ratio between the demolition and the production phase given in the EPD (6) for both impacts, as being the same for the UHPC. The demolition phase uses about 11.5% of the energy used for concrete UHPC production and emits 7.3% of the amount of CO2 that had been emitted during production phase. It would have been important for normal strength concrete to take into account the CO2 uptake due to concrete carbonation, which means the reaction between the free portlandite (Ca(OH)2) and the CO2. However, it has been proved in the literature that UHPC carbonation is negligible because of the fact that the total amount of portlandite reacts with silica fume during pozzolanic reactions (13).
TABLE 3. Values for Energy (GJ) and CO2 Release (t CO2) for the Functional Unit wood 100.8 m3a fabrication transportation construction
energy CO2 energy CO2 energy CO2
energy maintenance CO2
energy demolition & end-of-life CO2
energy whole life cycle CO2 a
UHPC 17.5 m3
1915.2 (T.E) 554.4 (N.R.E) -48.4 16.7 1.7 0 0 579.6 (T.E) (Sc.1) 171.4 (N.R.E) (Sc.1) 354 (T.E) (Sc.2) 171.4 (N.R.E) (Sc.2) 579.6 (T.E) (Sc.3) 171.4 (N.R.E) (Sc.3) -12.2 (Sc.1) -2.22 (Sc.2) -12.2 (Sc.3) 7.1 (T.E) (Sc.1) 7.1 (N.R.E) (Sc.1) -738 (T.E) (Sc.2) 7.1 (N.R.E) (Sc.2) 7.1 (T.E) (Sc.3) 7.1 (N.R.E) (Sc.3) 20.2 (Sc.1) 37.1 (Sc.2) 3.9 (Sc.3) 2518.6 (T.E) (Sc.1) 749.6 (N.R.E) (Sc.1) 1547.9 (T.E) (Sc.2) 749.6 (N.R.E) (Sc.2) 2518.6 (T.E) (Sc.3) 749.6 (N.R.E) (Sc.3) -38.7 (Sc.1) -11.82 (Sc.2) -55 (Sc.3)
glue 0.42 m3
crane
generator
144
19.1
0
0
19.1 9.2 0.9 0 0 0
4.5 0 0 0 0 5.7
0 0 0 55.8 4.41 0
0 0 0 5.3 0.96 0
0
1.3
0
0
16.6
0
55.8
0
1.4
0
4.41
0
169.8
24.8
111.6
5.3
21.4
5.8
8.82
0.96
totala 2078.3 (T.E) 717.5 (N.R.E) -24.8 25.9 2.62 61.1 5.37 585.3 (T.E) (Sc.1) 177.1 (N.R.E) (Sc.1) 359.7 (T.E) (Sc.2) 177.1 (N.R.E) (Sc.2) 585.3 (T.E) (Sc.3) 177.1 (N.R.E) (Sc.3) -10.9 (Sc.1) -0.92 (Sc.2) -10.9 (Sc.3) 79.5 (T.E) (Sc.1) 79.5 (N.R.E) (Sc.1) -665.6 (T.E) (Sc.2) 79.5 (N.R.E) (Sc.2) 79.5 (T.E) (Sc.3) 79.5 (N.R.E) (Sc.3) 26 (Sc.1) 42.91 (Sc.2) 9.7 (Sc.3) 2830 (T.E) (Sc.1) 1061.9 (N.R.E) (Sc.1) 1859.3 (T.E) (Sc.2) 1061.9 (N.R.E) (Sc.2) 2830 (T.E) (Sc.3) 1061.9 (N.R.E) (Sc.3) -1.68 (Sc.1) 25.2 (Sc.2) -17.98 (Sc.3)
T.E. is the total energy, N.R.E. is the nonrenewable energy, and Sc are the different scenarios.
FIGURE 1. Total primary energy distribution (GJ).
3. Results, Analyses, and Discussion The complete table below (Table 3) shows the energy (GJ) and CO2 release (t of CO2 equiv.) for each phase for the functional unit. These results are presented in the diagrams below. Figures 1 and 2 show, respectively, the quantity of energy for each phase with and without counting the renewable energy for wood. Figure 3 deals with CO2 release. We will consider respectively the three scenarios. For scenario 1 and 3, it is remarkable that the most energy needed is in the production phase (73.4% of the total energy). It is noteworthy that the biggest proportion of this percentage is due to the wood’s renewable energy
(70%). We can then consider only the nonrenewable part of the energy. Such a simulation is presented in Figure 2. The production energy and the maintenance one develop in the same way and represent the two most important amounts (Figures 1 and 2). Thanks to the wood contribution, whose growth is mainly due to solar energy, the nonrenewable energy in production and maintenance phases (Figure 2) represents only the third of that in the total primary energy (Figure 1). The transportation, construction, maintenance, and demolition phases contribute, respectively, 0.9, 2.2, 20.7, and 2.8% of the total primary energy and 2.4, 5.8, 16.7, and 7.5% of the nonrenewable energy. VOL. 43, NO. 6, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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FIGURE 2. Nonrenewable energy distribution (GJ).
FIGURE 3. CO2 release (t CO2). Calculations show that the main part of the energy comes from the material. It is seen as a step toward improving the balance that bridge designers, involved in environmental impact reduction, should focus on the manufacturing phase. The second post in order of importance is that of maintenance. An economy in this post may be done by protecting the wood beams or finalizing new designs which can avoid replacing it during the bridge life cycle. On the other hand, we can notice that recycling or dumping wood leads to the same result in terms of energy. Scenario 2 (wood as energy heating) reduces by more than one-third the total energy. This 34% comes from wood energy growth; solar energy being partially recovered and converted into heat. We can notice the negative values in the CO2 release diagram for the fabrication and maintenance phase; it is due to wood CO2 biomasssthe dry wood contains 49.4% of carbon taken from the atmospheric carbon dioxide. The negative value of the maintenance phase leads to a contradiction: the more we repair the bridge, the more we reduce the CO2 impact of our structure. The maintenance of this kind of bridge is not as easy as we thought, the girder may need to be raised, and the wood beam need replaced, which needs more time and energy and releases more CO2. Thus we can consider that the value of CO2 release in this phase can vary between -11 t to zero (Sc.1 and 3) and between -1 and 10 t (Sc.2). For scenario 2, the gain of energy in the maintenance phase is counterbalanced by the overproduction of CO2 released by burning wood instead of natural gas. The end-of-life treatment leads to significant differences between the three scenarios. The most interesting scenario in terms of CO2 release appears to be that of the recycling chain (Sc. 2), because the CO2 biomass stored in the wood is counted in another field. Here, we have implicitly assumed that the panel chain industry should integrate the total amount of CO2 coming from bridge wood girders in LCA 2070
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panels. A more realistic vision is to distribute the amount of CO2 between the two fields LCA (allocation system), but we do not have any data to support such dispatching. Scenario 1 is also an interesting end-of-life treatment since 85% of wood is used for carbon dioxide sequestration. Although this solution may be surprising for many people, it remains quantitatively interesting, provided that treatment facilities are equipped with methane recovery, according to the assumptions stated in the wood EPD. Finally, the end-of-life treatment adopted in scenario 2 emitted the largest amount of CO2. We recall that this number is obtained by comparison with natural gas combustion, considered as our reference energy in this scenario. CO2 production is mainly due to the fact that one MJ obtained by burning wood releases more CO2 than the natural gas combustion. The full life cycle analysis highlights the differences between the 3 scenarios. The energy varies from 1860 to 2830 GJ, which represents a range of 34%, whereas the impact on the greenhouse effect varies from -18 to +25 tons of CO2. It should be noted that no scenario can be the winner on both impacts. According to the emphasis given to each of them, we will be able to choose one or the other. Thus, scenario 2 is in the first position, far ahead of the two others, in terms of energy, but in the third position with regard to the impact on the greenhouse effect. Scenario 1 has a negative value of greenhouse effect but this value is likely to switch to a positive one depending on the uncertainties considered in the maintenance phase. Scenario 3 is the only one giving a negative value of CO2 release, even if we take great uncertainty, such as 50%, on the transportation, construction and maintenance phases. Then wood recycling appears to be a good compromise. The aim of this work was to show the relevance of matching structural performance with low environmental impact. In this article, we presented a simplified environmental study of an innovative bridge deck structure devoted
to the energy impact and CO2 release. This analysis was carried out for the production, transportation, construction, maintenance, and demolition phases. In this analysis, we highlighted that the high proportion of wood provides an interesting CO2 overview. The CO2 captured during tree growth may be enough to offset the additional sources of production depending on the end-oflife scenario considered. This exploratory work should be extended by the analysis of the overall impact given in NF P 01-010; consumption of natural resources (kg eq. Antimony) and water pollution should be the next impact to focus on.
Acknowledgments We thank Mrs Estelle Vial from FCBA, Paris and, Mr. Philippe OSSET from Ecobilan Paris for their informed comments.
Note Added after ASAP Publication Due to a production error, two references were mistakenly omitted from the version published February 4, 2009. References 20 and 21 were added to the corrected version published on February 10, 2009.
Literature Cited (1) Pham, H.-S. Optimisation et comportement a` fatigue de la connexion bois-BFUP de nouveaux ponts mixtes. PhD Thesis, ENPC, Paris, 2007. (2) Tanis J. M., Delfino R., Le Roy R. Caron J. F., Foret G., Pham H. S., Cardin M., Bouteille S., Resplendino J. Preliminary design of new bridges, structures and new slabs, WP3, Deliverable D3.3, New road construction concepts, European project available at http://nr2c.fehrl.org/?m)23&id_directory)948, 2008. (3) Tanis J. M., Nicolas M., Cardin M., Keller T., Schauman E., Toutlemonde F., Godart B. State of the art review, a vision of new bridges, WP3, Deliverable D3.1, New road construction concepts, European project, available at http://nr2c.fehrl.org/ ?m)23&id_directory)789, 2008. (4) NF EN 1990. Basis of structural design; European standard, March 2003. (5) NF EN 1991-2. Action on structures; Part 2: Traffic loads on bridges; European standard, March 2004. (6) FCBA, ADEME. Caracte´ristiques environnementales et sanitaires d’une poutre en bois lamelle´-colle´ (Environmental product declaration of glulam girder (temporary version)); French Environmental Protection and Energy Management Agency: Angers, France, June 2007. (7) SNBPE, CIMBETON, ECOBILAN. Be´ton preˆt a` l’emploi: Fiche de de´claration environnementale et sanitaire, Commentaires et fiche (Ready mix concrete: sanitary and environmental product declaration); SNBPE: Paris, 2007. (8) Gartner, E. Industrially interesting approaches to “low-CO2” cements. Cem. Conr. Res. 2004, 34, 1489–1498.
(9) FD P 01-015: qualite´ environnementale des produits de constructionsfascicule de donne´es e´nergie et transport (Environmental quality of construction productssdata manual on energy and transport); French Standard;French Environmental Protection and Energy Management Agency: Angers, France, February 2006. (10) Volvo Truck Corporation: Emissions from volvo’s trucks document available at http://www.volvo.com/NR/rdonlyres/8F7802B01F27-49AD-9864-C84BCFFA5CCC/0/Emis_eng_20640_05008. pdf. (11) French Environment and Energy Management Agency and French Ministry of Ecology and Sustainable Development. Utilisation rationnelle de l’e´nergie dans les serres report; available at http://www2.ademe.fr/servlet/getDoc?cid)96&m)3&id) 44445&p1)02&p2)07&ref)17597, March 2007. (12) LIEBHERR: Mobile and Crawler cranes catalogue 2008. available at http://www.liebherr.com/downloads/Gesamtprogramm_ DEFISR_07.2008.pdf. (13) SETRA, AFGC Ultra High Performance Fibre-Reinforced Concretes: Interim Recommendations; SETRA: Paris, January 2002. (14) Baroghel-Bouny, V. Durability indicators: relevant tools for an improved assessment of RC durability. Proceedings of the Fifth International Conference on Concrete under Severe Conditions (CONSEC07); Tours, France, June 4-6, 2007; ENPC: Paris, 2007. (15) Resplendino, J. First recommendations for ultra-high-performance concretes and examples of application. Proceedings of the International Symposium on Ultra High Performance Concrete; Kassel, Germany, Sept 13-15, 2004, Universita¨t Kassel: Kassel, Germany, 2004; Vol. 3, pp 79-90. (16) Gerold, M. Economic efficiency of modern timber bridges s life expectancy and costs of maintenance. Struct. Eng. Int. 2006, 3, 261–267. (17) Eleazer, W. E.; Odle, W. S.; Wang, Y.-S.; Barlaz, M. A. Biodegradability of Municipal Solid Waste Components in LaboratoryScale Landfills. Environ. Sci. Technol. 1997, 31, 911–917. (18) French Ministry of Industry. De´finitions, e´quivalences e´nerge´tiques, me´thodologie pour l’utilisation du tableau de bord des statistiques du bois e´nergie (Definitions, energetic equivalences, methods for the use of wood energy statitic tables); report available at: http://www.industrie.gouv.fr/energie/statisti/tbb/notemethodologique.htm. (19) World Steel Association. Life cycle inventory of engineering steel availableondemandathttp://www.worldsteel.org/?action)lcaform. (20) NF EN ISO 14040: Environmental Management-Life Cycle Assessment-Principles and Framework, French Standard; French Environmental Protection and Energy Management Agency: Angers, France, October, 2006. (21) NF P 01-010: Qualite´ Environnementale des Produits de Construction: Déclaration Environnementale et Sanitaire des Produits de Construction, Environmental Quality of Construction Products (Environmental and Sanitary Declaration of Construction Products), French Standard; French Environmental Protection and Energy Management Agency: Angers, France, December, 2004.
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