Fresh and hardened properties of self-compacting concrete containing metakaolin

This paper presents the fresh and hardened properties of self-compacting concrete (SCC) containing metakaolin (MK). Totally, fifteen mixes including different MK contents (0–20% by weight of cement) with three water/binder (W/B) ratios of 0.32, 0.38 and 0.45 were designed. The fresh properties were investigated by slump flow, visual stability index, T50, V-funnel and L-box. The slump flow changes with hauling time were also considered. The hardened properties were tested for compressive strength, splitting tensile strength, ultrasonic pulse velocity (UPV), initial and final absorption and electrical resistivity. The fresh concrete test results revealed that by substituting optimum levels of MK in SCC, satisfactory workability and rheological properties can be achieved, even though no viscosity modifying agent was needed. MK inclusion significantly enhanced the compressive strength of SCC within the first 14 days up to 27%. Moreover, the compressive strength of SCC with MK can be predicted in terms of UPV by using multiple regression analysis. The tensile strength and electrical resistivity of the SCC containing MK were higher than those of the control SCC by maximum of 11.1% and 26%, respectively. A low absorption (below 3% at 30 min) can be achieved for MK mixes classified as “good” concrete quality. In general, it seems that 10% MK can be considered as a suitable replacement regarding to the economic efficiency, fresh and hardened properties of MK concrete.