Influence of exposure environments on the carbonation resistance of concrete structures

There is agreement that the greenhouse gases, in term of CO2 emissions, are the main contributor to global warming. Increasing atmospheric CO2 emissions are likely to increase the average of maximum temperature and reduce the relative humidity, RH. These changes in CO2 concentration, temperature and RH have considerable impacts on the durability of concrete structures, in particular, the carbonation rate, chloride penetration, and corrosion rate.
This study aims to investigate the potential impact of temperature, relative humidity and permeation properties on the carbonation resistance or depth of carbonation (DoC). The study programme involves casting samples with different water-cement ratio (w/c), 0.4, 0.5 and 0.6. These samples exposed to different temperatures of 25, 35 and 45°C and three levels of humidity 65, 75 and 85 %. Carbonation depth was determined using an accelerated environment test programme based experimentally on the BS EN13295:2004 by phenolphthalein indicator. The results have indicated that (i): The depth of carbonation (DoC) increased with the increase in water-cement ratio under different exposure environments. (ii): There is a considerable influence of relative humidity and relative increase in temperature on the carbonation depth in concrete structures. Finally, the permeation properties for all mixes used of concrete, porosity and gas permeability has a significant impact of DoC.