Influence of self-healing stimulated via crystalline admixtures on chloride penetration

The cracks in concrete provide a way of entry to aggressive agents. These can affect the structure durability, mainly when exposed to extremely aggressive conditions such as marine environments. This paper analyzes the effects of self-healing on the resistance to chloride penetration, being the healing capacity autogenous and stimulated by crystalline admixtures. First, the effects of chlorides on the concrete compressive strength have been studied. To this aim, concrete cylinders were exposed to different curing situations (moist room at 95% RH, immersion in a chloride solution -165 g/l NaCl - and wet/dry cycles in salt water) along a time frame ranging from 7 to 84 days. Secondly, the effects of chlorides on pre-cracked cylinders have been analyzed. To this purpose, other cylinders cured under the same three conditions as above, were pre-cracked at 7 and 28 days and were then similarly cured for further 1 to 3 months, inspecting the sealing of the cracks. Finally, chloride penetration was determined by boundary color change methodology. The final aim of the work is to determine the maximum crack width which can be sealed, in order to define a performance based durability design approach for structures in aggressive exposure conditions