Effect of Internal Moisture and Outer Relative Humidity on Concrete Carbonation

With steadily rising CO2 concentrations in the ambient air and fast-changing concrete compositions with reduced clinker contents, availability of reliable accelerated carbonation tests is crucial importance to design durable structures. This paper focuses on effects moisture under conditions different exposure conditions. Mortar prisms incorporating three cement types were cured stored at either 50% or 65% relative humidity (RH). Afterwards, carbonated humidities (50, 57 65%), (0.04, 1 3 vol.%) complemented by a series increased gas pressure (2 barg). High-resolution test methods used explain underlying mechanisms. The results show that pre-conditioning for two weeks—as currently suggested European Standard—seems be too short because initial inner content severely affects rate. Relative during 57% led higher rates compared 65%. In addition, climate data needs periodically (preferably permanently) recorded research experiments laboratory testing ensure fair interpretation experimental results.