Improvement of high performance concrete properties by using metakaolin

Metakaoiln is one of the reactive pozzolans which is used in recent years. This additive whi -ch is derived from kaolin clay is applied in Increasing mechanical strength and durability of concrete. It also can be used to improve the decorative features of concrete in some cases. In this study the effect of replacement of Metakaolin in percentages of 5، 10، 15 on fresh concrete properties (slump، air content، setting time،density)، mechanical properties (compres -sive،bending and splitting tensile strength) and durability (penetration depth of water، gas permeability،water absorption،electrical resis -tivity، Potential Alkali-Silica Reactivity (ASR) and chloride penetration) with control concrete with no pozzolan is investigated. Results show high improvement in concrete properties by adding the metakaolin amount in concrete.