In conclusion, the combination of moisture profile testing of drying concrete and the durability index tests, of oxygen permeability and water sorptivity, show that reinforced concrete structures with a high w/b are more susceptible to the deterioration mechanism of corrosion in areas with intermediate humidity (40 to 80 %) and temperature (20 ± 2ºC) levels.
Dry climates will protect the reinforcing from carbonation induced corrosion to an extent. However changes in humidity or cyclic wetting and drying will result in the initiation of the carbonation front, becoming self-sustained from the water released during the chemical reactions. In situations with very high humidity, the pores will stay saturated, protecting the concrete from carbon dioxide infiltration. A permeable and porous concrete micro structure can have both positive and negative effects on the initiation and propagation phases of corrosion, depending on the environment and humidity levels. With regard to carbonation induced corrosion, concrete should be designed with higher water binder ratios for extremely dry areas, and lower ratios for wet humid areas. The use of fly ash will create optimal conditions for carbonation and using increased cement content will result in the concrete being less durable. Small changes in cover depths can have major effects on the service life of structures.
The improved durability and cover layer of concrete relates directly to the deterioration mechanism of corrosion. Improving the durability and decreasing this quick drying will prevent the initiation stage of corrosion from taking place. It will also lengthen the propagation stage after initiation, allowing the structure to serve its intended life span. Rapid changes in humidity can have the most drastic affects on the corrosion mechanism, allowing the permeable concrete cover to dry at different rates, opening and closing the pores to harmful substances that will initiate the corrosion process.