The influence of chloride on the moisture transport in mortar and sand-lime

The corrosion of steel reinforcement caused by chloride penetration has a negative influence on life-time performance of concrete structures. Marine structures in the splash and tidal zones are an example of concrete structures where the steel reinforcement can get corroded due to chloride penetration. The corrosion of steel reinforcement, in these structures, begins with the wetting phase, where the concrete cover layer will be saturated with a chloride solution by capillary adsorption. In the drying phase, the water will evaporate leaving chloride behind. To quantify the interaction between moisture transport and chloride, an experimental set-up has been designed to measure the moisture transport through mortar containing chloride. In this experiment, standard mortar specimens with water cement ratio of 0.5 and a diameter of 100 mm are produced. Layers of 10 mm thickness are sawn from the specimens. These layers are exposed to different chloride solutions to obtain mortar samples containing three different percentages of chloride, 0,5%, 1,0% and 2,0%, of the mass of the sample. The samples are applied as a barrier separating two relative humidities of 55 and 75%. The moisture will diffuse from the side with the higher relative humidity to the side with the lower, through the sample. It is expected that the mass flux through the sample with a lower percentage of chloride will be larger than in samples with a higher percentage of chloride. First results are obtained from a sample without chloride. After comparing moisture flux of the different samples, it will be clear to what extent the chloride in the sample hinders the moisture diffusion.