### Some Properties of Concrete Containing High Fraction Volume of Metakaolin

#### Abstract

In this research, a study has been made on the effect of high fractional volume of replacement Metakaolin that results from grinding and burning the local kaolin from (Doeakhla zone / west of Baghdad / Iraq) with fineness of 18000 cm2/gm., and with temperature 700°C for one hour, on some properties of concrete (compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, density,absorption and drying shrinkage). Also, non-destructive tests have been made (Schmidt rebound hummer and Ultrasonic pulse velocity). In this study, ten concrete mixes have been used in two Groups to get a compressive strength 40 N/mm2 at 28 days. In Group A, the percentage replace of Metakaolin have been changed from (0-70) % by weight of cement with percent increment equal to 10% for each mix, andchange the maximum size of aggregates to determine the effect of changing the surface area of aggregate as variable on the properties of concrete-containing Metakaolin, The tests for all mixes were made at ages ranged from 1 day to 90 days after mixing and replacement a dosage of superplasticizer by water content of the mix to make a constant workability with slump 50±5mm. The aim of this research is tofind a type of concrete that can be used in dams as one of the types of mass concrete, concluded from this research that replacing 70% Metakaolin instead of cement mixing the compressive strength aged 90 days less than the 63%, splitting strength at 28 days less than 27%, flexural strength at 28 days less than about 27%, the modulusof elasticity at 28 days less than 54%, density of less than about 8% at 28 days, the absorption rate increases about 27% and drying shrinkage 1.65 * 10-4 at 60 days when compared all these tests with the reference concrete.

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