Sustainable bridges –LCA for a composite and a concrete bridge - Economical Bridge Solutions based on Innovative Composite Dowels and Integrated Abutments - page 38

4.2 LCI of steel elements

The LCI of steel products are compiled by WorldSteel, from data collected on steel sites be-
tween 2005 and 2007 [5]. Among the 14 LCI of steel products of WorldSteel, four have been
used in this LCA: “sections” for beams, “rebars” for shear studs and concrete reinforcement,
and “plates” for end plates.
During the dismantling of the composite bridge, steel sections, end plates and shear
studs are easily separated. Reinforcing steel which is physically linked to concrete is more
difficult to recover. The structural steel is directly transported from the dismantling site to the
recycling site, while reinforcing steel, embedded in concrete, is partially transported to a sort-
ing plant, separated from concrete and transported to the recycling site while the remainder
is sent to a landfill facility, cf. Fig. 6.
As a consequence, the recycling rate for sections, plates and studs is 99%, which cor-
responds to the findings of the European study on steel construction products [6] and 65% for
reinforcing steel, in line with the statistics recorded by the Steel Recycling Institute [7] and
the information gathered by [8].
Recycling of steel products avoids the production of virgin steel. The methodology used
by WorldSteel to integrate this benefit is the multi step recycling method [9], which is imple-
mented in a practical way by calculating an avoided impact that provides a credit to the steel
elements recycled at the end-of-life of the bridge.

4.3 LCI of concrete

The cement content required for this type of application is 320 kg/m 3 of concrete [10]. We
have used the unit process “concrete, normal, at plant” of the Ecoinvent database [11] for the
production of concrete with 300 kg/m 3 of cement and extrapolated the results proportionally
for 320 kg/m 3 .
At the end of life, concrete can either be land filled, or crushed and used to replace ag-
gregates [12]. After discussion with internal experts the following scenario has been chosen
for the EOL of reinforced concrete (schematized in “Fig. 6”):

35% of reinforced concrete is directly sent to landfill - thus embedded rebars are also
100% land filled;
65% of reinforced concrete is sorted: it is crushed to separate rebars from concrete, that
steel being 100% recycled;
For concrete, it was considered that after the sorting plant, 15% of the concrete is used
as aggregates and 85% is land filled.