Influence of Different Types of Metakaolin on Compressive Strength and Chloride Migration of Concrete

The use of mineral admixtures in concrete has grown in recent years, specially the highperformance ones, such as silica fume, nanosilica and metakaolin. Metakaolin has been extensively studied due to its high reactiveness. Thus, an experimental program was conducted to evaluate the behavior of compressive strength and non-steady state chloride migration due to differences of metakaolin characteristics. Three different metakaolins were characterized, then used in a 10% replacement ratio (of mass of cement), among two water/binder ratios (0.40 and 0.60) in concrete mixes. The results show that metakaolin increased compressive strength in every age tested. Moreover, durability properties were significantly enhanced due to the addition of metakaolin. Nonsteady state chloride migration coefficient of metakaolin concretes were noticeably lower than plain concrete. In general, the addition of metakaolin in concrete caused pore refinement and reduction in total porosity, which lead to enhancements of mechanical e durability properties of concrete.