Carbonation of Concrete at Different CO2 Concentrations in Combination with Mechanical Load

Carbonation is one of the most frequently observed damage processes leading to corrosion of steel
reinforcement in concrete structures. In concrete carbonation studies there are currently two
important concerns.
One is the huge difference in CO2 concentrations applied for accelerated testing between the
different standards, while these concentrations are in addition much higher than for natural
carbonation of concrete exposed to the outside air. Increasing the CO2 concentration above a
realistic level will change the reaction mechanisms which will lead to errors in the service life
estimation of concrete structures. In this project, the effects of different CO2 concentrations on
carbonation rate, reaction product assemblage and microstructure will be elucidated. The
interactions with effects of other relevant parameters such as concrete composition, age, relative
humidity, and temperature will also be assessed.
Another concern is that real-life structures have to function in loaded condition, and microcracks
caused by external stress will promote the transport of CO2 in concrete. In standard carbonation
tests, microstructural effects of mechanical loads are not accounted for, leading again to errors in
service life predictions. Here, the effect of mechanical loads on the carbonation resistance of
concrete will be quantified and standardized test setups and protocols will be developed. Finally,
transport and reaction models will be built for carbonation combined with load.