Effects of crack and climate change on service life of concrete subjected to carbonation

Abstract

Carbonation is among the primary reasons for the initiation of the corrosion of steel rebar in reinforced concrete (RC) structures. Due to structural loading effects and environmental actions, inevitable cracks have frequently occurred in concrete structures since the early ages. Additionally, climate change, which entails increases in CO2 concentration and environmental temperature, will also accelerate the carbonation of concrete. This article presents an analytical way of predicting the service life of cracked concrete structures considering influences of carbonation and climate change. First, using a hydration model, the quantity of carbonatable materials and concrete porosity were calculated. Carbonation depth was evaluated considering properties of concrete materials and environmental conditions. Second, the influence of cracks on CO2 diffusivity was examined. Carbonation depth for cracked concrete was evaluated using equivalent CO2 diffusivity. The effects of climate change, for example, growing CO2 concentration and environmental temperature, were considered using different schemes of carbonation models. Third, different climate change scenarios (such as Representative Concentration Pathways (RCP) 2.6, RCP 4.5, RCP 8.5 and upper 90% confidence interval of RCP 8.5) and time slices (such as 2000 and 2050) were used for case studies. By utilizing the Monte Carlo method, the influences of various climate change scenarios on the service life loss of concrete structures were highlighted.