Experimental Investigation into the Metakaolin Used in Concrete

Today, in most parts of the world, there has been a tremendous development in the technology of concrete to achieve high-strength concrete. The use of metakaolin (MK) in concrete to achieve high-strength and durable concrete has been in the concrete industry for several years. Due to its significant pozzolanic activity and reaction with calcium hydroxide in the cement, this material has reduced porosity and permeability and increased durability and strength in concrete. In the present study, the role of (MK) and its effect on the mechanical properties to achieve the optimum percentage of MK use for high strength and durability have been investigated. In this study, laboratory tests at early and hardened state including temperature change, slump, liquidity examination, water absorption, specific gravity of concrete, electrical strength test (indicating permeability and corrosion rate), and compressive strength test on samples with ۰, ۱۰, ۱۵ and ۲۰ percent cement-substituted MK at ۷ and ۲۸ days of age were tested on ۱۵cm cube specimens. The results showed that the addition of ۱۰% cement substitute MK in slump test, ۱۵% cement substitute MK in compressive strength test, and ۲۰% cement substituent MK in electrical resistance test had the highest values and ۱۵% cement substitute MK in concrete weight density test. ۲۰% of cement-substituted MK in the experiment showed the lowest water absorption percentage compared to other mixes designs. Microscopic analysis shows the more durable MK replacement in comparison with normal concrete.

کلیدواژه ها:

Pozzolan ، Metakaolin ، Durability ، Mechanical properties ، Temperature Tests