Durability analysis and environmental impact of ultra-high performance fibre reinforced concrete (UHPFRC) for bridge applications

Durability evaluation of reinforced concrete (RC) bridges in aggressive environments imposes special attention to the evaluation of corrosion of reinforcing steel bars since it impacts significantly on the direct and indirect costs in existing RC structures. Bridges can experience sudden failures, even under ordinary loading conditions, if suitable actions are not implemented on time. On the other hand, in the context of structural rehabilitation, adequate innovations in design with regard to materials and geometries as well as choice of time for the intervention, should be accurately investigated in next few years. Efforts towards new best practice in design may have an even greater and certainly faster environmental impact on reducing harmful carbon dioxide emissions, but also raw materials consumption, than limiting to push towards technological advances in cement production . Different interventions of repairing or retrofitting of RC bridge column damaged by seismic action have been previously proposed. Among these, repair the columns through a jacket of concrete, steel or FRP, with or without substitution of damaged longitudinal rebars, have received great interest. A comprehensive review of these technique is proposed in [1]. In addition, the authors of the present paper also proposed a rehabilitation technique which is reported in [2],[3][4]. In this perspective, ultra-high performance fibre reinforced concrete (UHPFRC) can be a viable solution to deal with durability and sustainability issues. Thanks to its very low permeability [5], [6], UHPFRC is especially attractive to lengthen the lifetime of new structures or to extend that of existing constructions when used as retrofitting material. Hence, the present work aims to investigate numerically the possible replacement of normal strength concrete (NSC) of the cover, damaged by reinforcement corrosion, with one in UHPFRC, also considering the possibility to replace corroded longitudinal steel rebars. The simple substitution of the cover with NSC is also presented for comparison.