UHPFRC as Low-Carbon Solution for Bridge Rehabilitation: The Case Study of Annone Overpass

Globally, mobility networks are strategic infrastructure systems affected by high material intensity, which cause large carbon emissions from construction. Recent bridge collapses have raised concern about the urgent need of maintenance of the networks, and large investments are required to implement rehabilitation programmes to reduce the risk of failure. In this paper two alternative scenarios, bridge renovation vs. demolition and reconstruction, are investigated though a Life Cycle Assessment to evaluate the carbon saving potential from avoided material processing and indirect impacts due to bridge rehabilitation. The Annone Brianza overpass, a reinforced concrete bridge built in early ‘60s and collapsed in October 2016, is considered as case study. The demolition of the collapsed bridge and the consequential reconstruction with a mixed concrete-steel structure was assumed as reference scenario. The carbon emissions caused by materials production, construction and demolition are compared with the ones caused by a hypothetical rehabilitation scenario based on a “smart solution”, which requires the installation of thin UHPFRC plates anchored to the existing beams to reinforce the damaged half-joints and provide the required stiffness to restore the global safety of the structure. From the results achieved, the rehabilitation of the bridge with the UHPFRC repairing system can reduce the carbon footprint over the lifetime of the bridge up to 14-folds compared to the demolition and reconstruction scenario, with a resulting carbon saving of around 560 tCO2-eq.