Reliability-based durability requirements for RC structures made of low-carbon concretes in climate change conditions

Concretes with high contents of supplementary cementitious materials (SCMs) such as fly ash and ground granulated blast-furnace slag, typically exhibit reduced resistance to carbonation compared to conventional Portland cement concrete. The current study examines what durability requirements should be applied to reinforced concrete (RC) structures made from such low-carbon concretes to prevent unacceptable damage caused by carbonation-induced corrosion throughout their design service life. The requirements are determined based on two durability limit states–depassivation of reinforcing steel and excessive concrete cover cracking due to corrosion. The evaluation is carried out in a probabilistic format for RC components of a road bridge with a design service life of 100 years. For such a long lifespan, the effects of climate change on carbonation and the resulting corrosion need to be considered. This is done for three different types of concrete–ordinary concrete and two low-carbon concretes, two IPCC emission scenarios–SSP2-4.5 and SSP3-7.0, and three representative locations with very different climates–Dubai, Dublin and Seoul. The study's results show that accounting for the corrosion propagation stage, which follows the depassivation of reinforcing steel, is essential for establishing efficient durability requirements for RC structures made from low-carbon concretes in XC3/XC4 environments.